Sand dunes and beaches

I TA L I A N H A B I TAT S

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I TA L I A N H A B I TAT S

M I N I S T E R O D E L L’ A M B I E N T E E D E L L A T U T E L A D E L T E R R I T O R I O

M U S E O F R I U L A N O D I S T O R I A N AT U R A L E · C O M U N E D I U D I N E

Sand dunes and beachesEnvironments between land and sea

Italian habitatsItalian Ministry of the Environment and Territory Protection / Ministero dell’Ambiente e della Tutela del TerritorioFriuli Museum of Natural History / Museo Friulano di Storia Naturale · Comune di Udine

Scientific coordinatorsAlessandro Minelli · Sandro Ruffo · Fabio Stoch

Editorial commiteeAldo Cosentino · Alessandro La Posta · Carlo Morandini · Giuseppe Muscio

“Sand dunes and beaches · Environments between land and sea”edited by Sandro Ruffo

TextsPaolo Audisio · Giuseppe Muscio · Sandro Pignatti · Margherita Solari

In collaboration withAlessio De Biase · Luca Lapini · Lorenzo Chelazzi e Isabella Colombini (Tipology of habitats)

English translationElena Calandruccio · Gabriel Walton

IllustrationsRoberto Zanellaexcept for 67, 73 (Niccolò Falchi) and 102 (Franco Mason)

Graphic designFurio Colman

PhotographsArchive Museo Friulano di Storia Naturale (Ettore Tomasi) 49/2 · Paolo Audisio 6, 14, 20, 30, 31, 32, 33,37, 40/1, 40/2, 41, 42, 43, 44/1, 44/2, 44/3, 51, 52/2, 58, 60, 61, 63, 64, 69, 72, 76/1, 79, 81/1, 81/2,83/1, 83/2, 84, 92/1, 92/2, 94/1, 95/1, 97, 98, 106, 114, 118, 124, 125, 127, 129, 131, 133, 135, 137,139, 142/1, 142/2 · Enrico Benussi 108/2 · Roberto Bigai 52/1, 140 · Maurizio Biondi 142/3 · Giuseppe Carpaneto 48, 86 · Achille Casale 107, 119 · Compagnia Generale Ripreseaeree 10, 18 ·Ulderica Da Pozzo 112 · Dario Ersetti 34 · Gabriele Fiumi 94/2 · Paolo Fontana 80, 95/2, 96, 103 ·Istituto Geografico Militare 19 · Luca Lapini 111 · Paolo Maltzeff 76/2, 78, 88, 91, 93/1, 101 ·Ugo Mellone 7, 9, 128 · Michele Mendi 110 · Giuseppe Muscio 16, 49/1, 145 ·Roberto Parodi 53, 109/1, 109/2 · Sandro Pignatti 38, 116/1, 116/2 · Paola Sergo 56 ·Margherita Solari 28, 36, 47 ·Antonio Todaro 70, 71 · Elido Turco 123 ·Augusto Vigna Taglianti 74, 75, 90, 93/2, 108/1, 142/4 · Roberto Zucchini 104

© 2003 Museo Friulano di Storia Naturale, Udine, ItalyAll rights reserved.No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form orby any means, without the prior permission in writing of the publishers.

ISBN 88 88192 11 5

Cover photo: footprints of a wild rabbit (photo by Paolo Audisio)

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Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Paolo Audisio

Geological and geomorphological aspects . . . . . . . . . . . . . . . . . . . . . . . . 11

Paolo Audisio · Giuseppe Muscio

Paleogeography and biogeography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Paolo Audisio · Giuseppe Muscio · Sandro Pignatti

Beach vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Sandro Pignatti

Sandy shores and their animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Paolo Audisio

Problems of conservation and management . . . . . . . . . . . . . . . . . . . . . . 113

Paolo Audisio · Giuseppe Muscio · Sandro Pignatti

Suggestions for teaching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

Margherita Solari

Select bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

List of species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

ContentsItalian habitats

1Caves andkarsticphenomena

2Springs andspringwatercourses

3Woodlandsof the PoPlain

4Sand dunesand beaches

5Mountainstreams

6TheMediterraneanmaquis

7Sea cliffs androckycoastlines

8Brackishcoastal lakes

9Mountainpeat-bogs

10Realms ofsnow and ice

11Pools,ponds andmarshland

12Aridmeadows

13Rocky slopesand screes

14High-altitudelakes

15Beechforests of theAppennines

Shore and sub-shore beaches andsand dunes, together with damp, silty-sandy environments of shore dunesusually associated with them, are oneof the most vulnerable and seriouslyendangered ecosystems in the world.Until a few decades ago, in theMediterranean and in Italy, thesepeculiar environments had eludeddirect destruction and severe damagebecause, throughout the centuries,man had colonized only areas nearmouths of rivers and sheltered bays.Unfortunately, in recent years, theseecosystems have been variously disturbed and damaged by man’sintervention: pollution of coastal waters, urbanization, fires, tourism, agriculture,thermo-electric power stations and industry, port activities and removal ofsands for building purposes.Another potential, future danger is the feared rise in sea level (associated withthe scientifically documented rise in mean annual temperature worldwide),which would further jeopardize these fragile and little-extended marineenvironments, despite the dynamic structure - i.e. the considerable resilience,or ability to recover;, of their biotic communities. Even intense coastal erosionmay locally reduce the size of these habitats, although erosion andaccumulation are natural evolutions of beach-dune environments. These events, combined with the growing exploitation of shores by man, havefragmented these habitats, which must now be monitored and safeguarded.Deeper knowledge of plant and animal communities of beach and sandyshore dunes, of hydrogeological and geomorphological dynamics whichdetermine their formation and evolution, are therefore essential for environ-mental protection, both at national and European Community levels. Thespread of knowledge is essential in making everybody aware that these

7IntroductionPAOLO AUDISIO

Mouth of river Irminio (Sicily): a beach stretch of good environmental quality

Vegetation on a sand dune

ments of various vegetation), which are not exclusive to damp, sandy shoreenvironments (salicornia, jonquils, coastal reeds beds etc.). Obviously, thelarge numbers of birds which live or shelter, particularly during the winter, onbeaches, mouths of rivers, marshes and interdunal brackish lagoons, or all theaquatic communities which live in those areas, are not studied in this book.The complex mesopsammon of sand and gravel under the beach surface (i.e.,all those microscopic, unusual, specialized animals which live in large num-bers in interstices between sand grains), is not treated here, because they areexclusively with aquatic environments, although it is linked with land and sea.Those who are interested in this peculiar and fascinating “miniature world”may find information in the box devoted to mesopsammon (pp. 70-71). This book treats the most characteristic and peculiar animals and plants whichspend all their life, or most of their lifecycle, in these mainly terrestrial environ-ments in Italy, where they constitute natural populations. It also discusses pro-tection and management problems regarding this ecosystem, its communitiesand single species.

9ecosystems must be protected. Unlike other terrestrial habitats, beach andshore sand-dune ecosystems have simple plant and animal communities anda very few species, due to their peculiar environmental and microclimatic con-ditions and restricted extent. However, these environments have selectedpeculiar and specialized plant and animal elements, due to the very presenceof extremely limiting abiotic parameters and generalized conditions of severeenvironmental stress.This has given rise to high numbers of specialized psammophilous organisms(exclusively associated with brackish and sandy shore environments) in bothplant communities and animal ones (particularly arthropods), in comparisonwith the remaining species which constitute biotic communities. The analysis of animal and plant communities in dunes and dune heath evi-dences frequent overlapping of floral components and faunal ones, especiallyxero-thermophilous, psammophilous or hygrophilous components which donot only live in shore and surrounding environments (Mediterranean or sub-Mediterranean maquis and garrigue), but also in steppe-like meadows, moors,brackish-sandy terrestrial environments near rivers and lakes, or aeolianrocks. Particularly in central-southern Italy and its islands, beaches, dunesand dune heath are “hedges” for many terrestrial organisms (especially coastalones, but not only) which are passively or almost passively carried on seastretches by currents, winds and floods during storms and exceptional meteo-rological phenomena. The naturalistic value of these rare coastal communities lies in the co-exis-tence of various elements of different biogeographic origin which share highlevels of trophic specialization. They are exclusively found in these areas, andare therefore good “indicators” of the general biological value of the ecosys-tems in which they still live.This book analyses the main characteristics of Italian sand dunes and sandshores from the geomorphological, floristic, vegetational and faunistic pointsof view, and their very different types. Differences depend on the great latitudi-nal and bioclimatic extent of Italy and its islands, and on the influence of vari-ous, completely different biogeographical and historical factors which deter-mine animal and plant populations.This book does not deal with the large numbers of heterogeneous, typicallymarine organisms which occasionally or regularly visit sandy shores as strand-ed remains or masses of organic matter, unless these remains are typicallyused by sand animals as food or shelter. In the same way, it does not describetypical inland organisms which are occasionally found on beaches and sanddunes, and eurytopic hygrophilous organisms (associated with damp environ-

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Passage from sandy shore to Mediterranean maquis

Beaches are narrow strips of accumulated sand between sea and land. Theyare extremely dynamic areas, where balance is determined by various factorswhich may be divided into two groups: passive (topography of the area, mate-rial) and active (winds, waves, sea currents, tides, river supply, activity oforganisms, including man!).Sand beaches are composed of incoherent rock sediments of alluvial andmarine origin, the particle size of which is fine, but not very fine (sand is con-ventionally made up of fragments the mean inferior diameter of which is 2 mm;when grains are much smaller and between 0.06-0.004 mm it is called silt; ifgrains are even smaller, it is clay; grains exceeding 2 mm form gravel).The Italian word spiaggia (beach) comes from piaggia, which derives from theLatin plaga meaning “flat extension”, and from the Greek plagio meaning“lateral” and its verb piaggiare (to sail along the coast), with the prefix s-identifying a lasting action. The word dune defines the narrow, long, shore orsub-shore area which usually stretches parallel with the coastline and ischaracterized by low rises (in Italy, between 1.5-12 m, with a few exceptions inSardinia), constituted by wind-deposited incoherent sediments. Sand dunesare made up of more or less incoherent sand, according to its age and vegetalpresence, the upper layers of which are compacted. The word dune comesfrom the Middle Dutch dune which means “small rise, hill, high ground”.Most of the longest, stabler and more complex (therefore more significant inbiocenotic terms) sand-dune systems, form where shore stretches are low andmarked by plains landwards and shallow depths seawards.

■ Beach structure

Technically, beaches are shores made up of loose material which moves withthe waves, and are produced by constructive phases, although some areasmay be eroded in certain periods. Beaches have variable stretches: if they are associated with rocky coasts, theyare only narrow strips of loose sediments along which emerging rocks are notsplashed by the sea, and they may develop into small bays. Near deltas or

11Geological and geomorphological aspectsPAOLO AUDISIO · GIUSEPPE MUSCIO

Dispersion of sediments at mouth of river Tagliamento (Friuli Venezia Giulia)

Normally, the lower stretch, which indicates the limit of sand carried by back-wash during high tide, is another ridge, which limits the waterline seawards.Beyond this ridge is the so-called low-tide terrace which is often character-ized by bars and banks (small ridges organized longitudinally, parallel or sub-parallel to the shore), which are formed in the temporarily submerged beachby waves or local currents. The upper and lower limits of the waterline areobviously variable and depend on the height of breakers and tide levels. Submarine beach is the seaward portion of a beach, between the mean levelof low tide and mean depth considered to be half the mean wavelength duringsea-storms. Also in submarine beaches there are more or less evident bars orbanks preceded by small hollows called troughs. Beaches are therefore variably inclined slopes where the energy of wavesdampens. Normally, slope gradient increases if the incoherent material carriedand washed away is coarser: this phenomenon is due to hydrodynamics, asthe gradient of the waterline is determined by the alternating movement ofincoming material pushed by swash and out-going material carried away bybackwash. Although kinetic energy is equal, fine material like sand can becarried downwards on gentle inclinations, and coarser material such as gravelor pebbles needs higher gradients. Remodelling and re-adaptation of beachwaterlines is always determined by a temporary, dynamic balance.Exposed beaches, where sand is dry, are affected by wind which creates andmodels dunes and sand-dune systems.

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estuaries, beaches may be so large as to block part of the system. But thebest place for the formation of large dune systems is near broad plains.Conventionally, beaches stretch landwards as far as the limit of stormingwaves, and seawards as far as a mean depth calculated as half the meanwave length during sea-storms. The movement of sand particles caused bywaves at lower depths is considered negligible.This large stretch of coast may be divided into three sections, proceeding sea-wards: exposed beach (or sandy shore), intertidal beach and submarine beach.Exposed beach is the emerged area included between the limit of stormingswash and the so-called ordinary berm, i.e., the clearly visible ridge modelledby breakers (but also erosion and accumulation) inside the limit of the water-line. Waterline is that beach stretch which slopes seawards and on whichswash and backwash alternate (backwash is the return of water which ispushed ashore by swash). There are high- and low-tide waterlines, with a ver-tical variation between the two (i.e., imaginary lines which join points of thebeach splashed by swash) of about 30 cm in Italian seas. Inside the exposedbeach, there is another ridge called storm berm, which indicates the maximumlevel reached by swash during the last sea-storm. Storm berms form after vio-lent storms which alter the beach morphology. They are usually preceded by asmall, sudden slope called beach scarp.Intertidal beaches are areas between the mean levels of high and low tide.Proceeding landwards, their first part is composed of the high-water line.

12 Geomorphological description of a beach-dune system

dune

dune

interdunal lagoon

storm berm crest ordinary berm crest waterline hollowwaterline

foot of dunestorm berm

exposed beach

ordinary berm

submerged beach

bar bar

part of the sand which makes up the waterline may be drifted away by wavemotion to form bars in submarine beaches, or be carried offshore.The opposite occurs in summer, when weak waves carry all the material backto the coastline. Sand beaches are, therefore, considerably different through-out the year: in summer, they are wider because there is more sand; in winter,all the material accumulates in the submerged portion as bars.

■ Structure of a shore sand dune

Sand dunes are variously shaped mounds of windblown sand. We have alreadydescribed the causes for the formation of exposed beaches which the windshapes in shore sand dunes by carrying sand deposited by waves and storms. Shore sand dunes, except for their position, do not differ greatly from othertypes of dunes which form inland, in continental areas where wind deeplyerodes substrates. There are various types of sand dunes, according to theirorientation and organization with regard to wind direction. Shore sand dunesare usually transverse dunes i.e., they face the wind; if they form behindbeaches and crescent-shaped sand bays, they are called parabolic dunes.Most shore dunes are transversal, the upwind face of which (usually the sea-ward one) is less steep than the lee (usually facing inland). Sand climbs thewindward face as saltating or bouncing grains until it reaches the crest, wheregravity makes grains bounce down the lee. Shore dunes may have variablysinuous crests produced by winds blowing in different or opposite directions.The difference between shore dunes and mobile continental dunes lies in thevegetation of the former, which has a “hedging” effect, preventing dunes frommoving landwards. As soon as pioneer psammophilous vegetation develops,accumulation and consolidation of windblown sand occurs on the spot, whichgreatly affects the geomorphological evolution of the dune. As vegetation develops permanently only at a certain distance from the coast-line, the formation of shore dunes may only occur parallel to the coastlineitself, as they only partially depend on the direction of the main winds.

15■ Dynamics, formation and erosionof sand beaches

The formation and evolution of sandbeaches are closely linked with variousfactors, such as debris supply, confor-mation and geological origin of nearbycoasts, transportation and accumula-tion of debris by waves and currents.The main agents in the modelling ofbeaches are waves and currents and,

especially in the exposed portion of the beach, wind is also important, as it isthe chief cause of wave formation. Tides are not as important, although theyoften shape the long stretch called intertidal beach. Debris supply is fosteredby nearby rivers and watercourses which efficiently carry sand, mud and allu-vial debris of various sizes. Debris may also derive from the contemporaneouserosion of nearby coasts and it is carried by the homogenizing and regulatingaction of waves, which smooth coastal protrusions by washing away materialand depositing it on the sides of the protrusion itself, usually in sheltered bays.Sand may be eroded from depths near the coast.When beaches are near river mouths, large quantities of debris accumulatealong nearby coasts. In large accumulation areas, debris is organized accord-ing to its weight and energy necessary to carry it. If the sea bed is steeplyinclined, gravity pushes debris offshore, where it cannot be washed ashoreagain. If the sea bed is gently inclined, oblique waves form offshore, and onlyweak waves reach the coast, which is therefore marshy, with clay and silt. Inother areas, accumulation is due to the combined transport of material to thewaterline and is called longitudinal transport i.e., parallel to the shore.In order to understand how debris is carried by waves, dynamics and kineticsof wave motion must be analysed. As is well-known, waves are usuallyproduced by wind, which conveys part of its energy to surface water andpushes it in a horizontal wave motion, according to direction of propagationperpendicular to wave crests. Near shores, the gradient and faces of sea bedsand coasts may change the direction, shape and energy of waves. Particularlyimportant are waves produced when the water carried by water crests is fasterthan the speed of propagation of the wave itself and fall forming beachbreakers, which use up all their kinetic energy to reach the shore as swash. Atthis point, gravity makes swash recede as backwash. This situation undergoesseasonal variations: during intense winter storms, breakers are stronger and

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UPWIND FACELEE

ORIENTATION OF WINDS

Evident signs of erosion on a Sicilian beach

■ Dynamics and formation of sandshore dunes

Eroded sand which is carried anddeposited by wave motion and winds,often accumulates inside small bays(so-called crescentic dunes), or formslateral, leeward longshore bars whichclose off small, shallow bays or joinislets near the shore with the coast,producing peninsulas. When long-shore bars are covered with dunesthey are called beach rock.Longshore bars, which are often

inappropriately called strands, may look like islets or elongated peninsulas, orjoin the mainland at both ends.They are outcropping underwater banks where large quantities of debris slowlyemerge as sand mounds. Instead, beach cusps have peculiar, cuspidate ortriangular shapes. They occur when debris is carried by two opposite waves

the uprush of which concentrates towards protruding points (apexes)separating two diverging coastlines. Beach rock is composed of sand dunes shaped by wind and wave motionwhich form on beach cusps. As their transversal length is very short, they areextremely fragile and dynamic environments. The evolution of beach rocksometimes leads to the complete erosion of longshore bars. The continualdrifting of the coastline seawards (which is associated with river supply ofincoherent material) may cement beach rock to sub-coastal fossil dunes (orpaleo-dunes).These environments are very interesting from the naturalistic point of view,and their evolutionary balance is very fragile, as it is linked with the continualtransformation of the substrate and surface sheets. The formation processesof beach rock may lead islands to become part of the mainland, in the shapeof peninsulas. A typical example is the Argentario Promontory, where twoactive beach rocks and a central longshore bar, with the town of Orbetello,joined the mainland. These three longshore bars gave rise to two shoremarshes.

■ Substratum of beaches and dunes in Italy

The geomorphology of substrates is determined by the analysis of modellingfactors and particle size of elements which constitute them. When beaches anddunes are considered habitats, the chemical mineralogy of substrates is highlyimportant i.e., the identification of mineral components which constitute grainsand, therefore, the chemistry of substrates themselves. Grains which make upbeaches and dunes are usually carried by rivers into the sea or directly tobeaches, and their mineral content depends on the type of rock outcropping inthe river basin itself. Furthermore, different rocks, and the different mineralswhich compose them, have different resistance to erosion and transport andtherefore, if particle size is equal, more resistant grains may be carried farther.For instance, among common minerals, quartz is the most resistant and is fre-quently found in beaches formed by rivers which cross long plain stretches.Sand grains are carried by rivers, but their distribution is not symmetrical withregard to watercourse outlets in seas. Sea currents scatter them unevenly. Inthe upper Adriatic, for example, fluvial deposits sediment westwards withregard to mouths; in the river Isonzo, deposits reach Lignano, and in the riverTagliamento, they reach Jesolo and mix with those of the river Piave. The lat-ter scatter as far as the lagoon of Chioggia.Supply origin produces different particle sizes and mineral contents which are

1716

Geomorphology of a coast

beach cusp

beach

lagoon

barrier islands

estuary

cliffs with beach

hollow beach

Dune systems at Is Arenas (western Sardinia)are among the most extensive in Italy

19linked to one another in some way. As regards the upper Adriatic, northernbeaches, the tributaries of which drain the Alps, have particle size classes of95-99% between 2-0.03 mm; beaches near estuaries which flow on marl-sandstone deposits of the Appennines have higher percentages of finer ele-ments (between 10-20% of grains smaller than 0.03 mm). However, mineralcontents may have greater and more complex variations, and the followingvalues are only indicative.In the stretch between Grado and Lido di Venezia, 80-90% of minerals are ofcalcareous-dolomitic origin with 20% of quartz and flintstone, as the riverswhich supply these areas drain calcareous rocks.Beaches supplied by the rivers Adige and Brenta are richer in quartz (about40%) and other elements of acidic vulcanic origin (which decrease in theRomagnese area) and fewer - 15-30% - carbonate elements (calcareous andnon-dolomitic). Southwards, in the Marches and Abruzzi, the carbonate con-tent rises (30-60%) and quartz decreases (20-40%).In the Campania and Latium regions, there are high quantities of feldspar(20%), with quartz (25%) and calcium (40%). Tuscan shores have low quanti-ties of calcium north and south (about 20%) and rise in central areas (50%).The opposite happens with quartz, which peaks north and south (over 50%),drops in the centre (20%) and peaks again near Follonica (60%).Beaches in northern Sardinia are mainly composed of calcium (between 30-80%) and quartz (10-30%). Towards Sassari, calcium drops to 10% and quartzreaches 40%; the same occurs in the Gulf of Orosei. The area around the city ofAlghero has many variations, but quartz and calcium always prevail. AllSardinian shores are characterized by iron (1-3%). In Sicily and shores aroundCatania, there are large quantities of quartz (60%) and little calcium (20%).

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Aerial view of sandy Adriatic shore between Bibione and Bibione Pineta (Veneto) Left: a natural beach; right: man’s intervention is clearly visible

Aerial view of Argentario area, with beach cusp surrounding Lagoon of Orbetello (Tuscany)

The biogeographical structure of Italy is affected by the complex position ofthe Italian peninsula, which is wedged into the Mediterranean basin. The pre-sent flora and fauna, likely the most numerous and dissimilar of all Europe, areinfluenced by the geological evolution of this area which, in the last millionyears, has been associated with different European and circum-Mediterraneanareas. The description of Italian beaches and dune systems must include thewhole Mediterranean and its recent history, at least until the most importantevents which determined both the present shore morphology and its animaland plant communities.

■ Paleogeopraphic, paleoclimatic and biogeographical outlines

About 65 million years ago, in the Paleocene, at the beginning of the Cenozoicepoch, Europe and Asia were separated by a narrow, epicontinental seastretch (i.e., with shallow waters) which joined the present marine areas of thePersian Gulf with the Artic Sea, passing eastwards of the present boundary ofthe Ural Mountains (Turgai or Uralian Sea). Eastwards, the Mediterranean waslinked with the Indian Ocean, forming a partly epicontinental sea which wasnarrow in width in some points, but incredibly long, known as Tethys. TheItalian and Balkan peninsulas had not yet formed, and there was a tropical orsub-tropical climate along the margins of the Tethys.Towards the end of the Eocene, about 40 million years ago, the Tethys couldstill be found along the east-west line, but the Turgai Sea dried out, creating aterrestrial passage between Asia and Europe.In the Oligocene, about 36 million years ago, Eurasia was a vast area whichincluded most of today’s northern Asia and central-northern Europe, andsouthwest, some areas started outcropping from the sea, which would laterbecome the present north Mediterranean lands. As the African and Eurasiancontinental plates drifted towards each other, the Alpine orogenesis started,and the Tethys began narrowing eastwards. Like a macroscopic puzzle, piecesoutcropped and organized into what became their present positions, such asthe Italian peninsula and its islands. In the west, Corsica, Sardinia and the

21Paleogeography and biogeographyPAOLO AUDISIO · GIUSEPPE MUSCIO · SANDRO PIGNATTI

Sea bindweed (Calystegia soldanella)

dried out. The remains of this epicontinental sea are the Caspian Sea and theBlack Sea, which only later was linked with the Mediterranean again. Fewer than 6 million years ago, another devastating event affected theMediterranean area: the large sea stretch between today’s Iberian Peninsulaand the Baetic Rif chain of the African plate closed very quickly, separating theMediterranean Sea from the Atlantic Ocean. This phenomenon was due to thecombined actions of the Earth’s lowering sea levels and the outcropping ofareas along its coasts. This affected coast morphology only locally, butinfluenced the net hydrological balance of the Mediterranean very negatively.Today, of the annual 1400 km3 of freshwater supply (water from catchmentbasins and rainfall), 4800 km3 evaporate in the atmosphere, with an annual netloss of about 3400 km3. Considering that the total volume of water of theMediterranean is about 3.7 million km3, it is easy to calculate what couldhappen today if the Strait of Gibraltar (and also the Suez Canal) were suddenlyclosed. In a thousand years, the entire Mediterranean would dry out(3.7million/3400 = 1088 years, but even fewer, because rainfall in the wholedried area would reduce locally and move eastwards).What happened in the Miocene is exactly the same as we have described in

23Balearic Islands were still part of the Catalan-Provençal area but, in the earlyMiocene (about 23 million years ago), they slowly drifted away and started amigration which took them to their present position. Micro-plates sub-parallelto the Sardinian-Corsican-Balearic Arch started moving and formed theCalabrian-Peloritan Arc in the east and the coasts and sub-coastal mountainsof today’s northern Algeria in the west. In the south-east, the Apulian Peninsulaslowly outcropped, although still connected in the Oligocene to other areas ofthe Balkans, the central-eastern Mediterranean, and western Anatolia. In the same epoch, the African and European plates kept drifting towards eachother, giving rise to other important mountains in the east; at the same time,sea levels lowered, due to the formation of the western Antarctic ice cap. TheTethys progressively closed in the east and the African and Eurasian flora andfauna, separated until then, could meet.About 15 million years ago, the western part of the Tethys, which was about toseparate from the Indian Ocean, divided into two distinct stretches: south-west, in what became the Mediterranean Sea, and north-east, the so-calledParathethys, which extended to south-eastern Germany and Pannonia, quick-ly changed from an epicontinental, shallow sea to a brackish “lake-sea” and

22

Paleo-geography of Mediterranean in Paleocene. Brown: exposed areas; grey: platforms: pale blue: sea;approximate position of Sardinian-Corsican plate also shown

Paleo-geography of Mediterranean in mid-Miocene. Brown: exposed areas; grey: platforms; paleblue: sea

Most handsomefungus beetles of thelycoperdine(=eumorphine) subfamilylive in woodlandenvironments, particularly intropical or sub-tropicalcountries where thesesmall insects feed on treefungi. Dapsa are a genusof small lycoperdinebeetles, which haveadapted to life in piles ofstranded plant debris onbeaches and coastal salicorniavegetation. In the lateOligocene, probably starting fromnorth-eastern parts of the Tethys, themost ancient members of this genusbegan to spread westwards, rapidlycolonizing damp, sandy environmentsnear coasts throughout the Tethys,from the north-eastern Atlantic to thenorth-western Pacific. After severalphases of marine transgression andregression, various populations andspecies of Dapsa followed theevolution of both Tethyan and paleo-

Mediterranean coasts,which left them isolated

inland, in areas oncesplashed by epicontinental

seas (such as the Paratethys).Other Dapsa were affected by

the tectonic emergence (e.g.,Canary Islands) or migration(e.g., Kabylic microplates innorthern Algeria) of entirecircum-Mediterranean

islands. Lastly, about 40species differentiated, most of

them on the coasts of what isnow the Mediterranean Sea, theislands of the Canaries, Madeira,

and the Azores, but many of themremained isolated in continental areaswhere the sea had dried up millions ofyears before, and thus adapted todamp woodland or bank ecosystems.If the present distribution of Dapsawere to overlap that of marine areas ofthe middle Miocene (about 12 millionyears ago), we would see how theserare and curious beetles may beconsidered true “beachmarkers” ofcoastal paleo-systems.

Beachmarkers Paolo Audisio · Alessio De Biase 25the science fiction hypothesis above: in the Messinian, 5.6-5.0 million yearsago, the Mediterranean partially dried out, coastlines drifted centripetallytowards and around the deepest areas, and essential terrestrial connectionswere formed for hundreds of thousands of years between northern Africa, theIberian Peninsula, Sicily, Corsica-Sardinia and Italy. The Tyrrhenian and part ofthe Sicilian Channel became large brackish seas, where rivers coming fromoutcropping lands poured their waters hundreds of metres below ocean level,creating deep gorges. This drying out had serious consequences on the bioticcommunities, particularly sea organisms, which were confined in hyper-brack-ish lakes and largely died out due to this devastating “salinity load”. Amongterrestrial fauna and flora, the most xerophilous, thermophilous andhalophilous elements (among plants, e.g., Tamarix and many halophilouschenopods) of northern African, middle-eastern and central-European originwere distributed along the coasts and sub-coasts. Many mesophilous andhygrophilous elements, which lived in rivers, lakes or mountain areas, alsoused these new terrestrial connections to colonize western Mediterraneanareas, giving rise to endemic species. Other elements moved westwards andreached the forming Italian peninsula. During the Messinian and the dry period

24

Paleo-geography of Mediterranean in upper Miocene (Messinian). Brown: exposed areas; pale blue: sea;shaded: evaporating seas

Sardinia and Corsica. Large numbers of Siberian or central-Asian speciesmoved towards south-western Europe and reached the Mediterranean, wherethey colonized sub-mountainous areas, cool and damp plains and coasts.During temperate interglacial periods, some of these species moved to higheraltitudes, others died out, and some survived as relicts near mouths of perennialrivers. At the same time, important steppe species of central and south-westernAsia moved to south and western Europe, as far as the Mediterranean coasts.Many of these species died out in the following glaciations, some of themmoved to high altitude steppe-like habitats, but a few survived and adapted totypical coastal habitats of both cliffs and dunes. In the Holocene, well after thelast glaciation (called Würm, dating back to 20,000 years ago), there still were,although to a lesser extent, cold and hot peaks. An important hot maximumoccurred 8500 years ago, another between 5000 and 3000 years ago. Duringthe latter, many Mediterranean species, which still live on beaches and sandshores today, were able to move to north-western Europe.During the Roman Empire, the climate became warmer and temperaturesrose, particularly in central-northern Europe, until the 12th century, when theycooled a little until the 18th century. Since then, temperatures have risen slow-ly, and continue to do so now. Further information regarding climate evolutionand its possible consequences on coastal environments is provided in thechapter on preservation and management of sandy coastal ecosystems.

27which followed the partial drying out of the Mediterranean, which had becomean almost brackish desert, many plants died out in terrestrial habitats.In the late Miocene, about 5 million years ago, and early Pliocene, the Strait ofGibraltar formed, creating a sea passage between the Mediterranean and theAtlantic Ocean. The Mediterranean filled up and sea fauna of Atlantic originflowed in. The post-Messinian re-population of land habitats occurred both bymeans of immigration from nearby areas and development of autochthonouselements which had moved to the preserved mountains and river estuariesduring the dry period. Although the Messinian was rather short, thedevelopment of today’s Mediterranean flora and fauna belongs to a laterperiod. The Italian peninsula and Sicily were forming, and coastlines adjustedto present altitudes, not very different from what they are today. Northern Italywas an exception - where a large gulf occupied the present Po Plain, whichoutcropped only 2 million years ago, in the middle-upper Pleistocene. Marinephases were more or less like those of today from the Pliocene until theHolocene. However, the climate was sub-tropical and flora was quite differentfrom today and more similar to that of south-eastern Asia.In the Pliocene, the climate, which had been dry in the Messinian, becamewarm-humid and temperate again, and many plant and animal species came infrom the north and east. The situation worsened again with the formation of theterrestrial Isthmus of Panama, which links southern and northern America,because it modified the transport cycle of warm tropical currents to thenorthern Atlantic, which became colder. This, and other complex astronomicalfactors, gave rise to the formation of Arctic ice caps, the cooling of the northernhemisphere, and the sudden adaptation of European and Mediterranean faunaand flora to a temperate climate. Many xerophilous, thermo-hygrophilous orsub-tropical marine and terrestrial species died out. Among terrestrialelements, many found refuge along the sea shores and mouths of rivers, wheretemperatures and waters were more suitable. A few million years ago, in theearly Pleistocene and Quaternary, climatic cooling became cyclic, andglaciations started, with at least six main peaks along the length of ice caps inthe northern hemisphere and Euro-Mediterranean areas. During glaciations, theclimate cooled down and large ice masses of 1000-2000 m formed in Europenear Alpine and Scandinavian areas. Ice and the higher mean density of coldwater deprived the sea of this liquid, and sea levels dropped more than 100 m.The coastlines of low seas, like the Adriatic, outcropped for hundreds ofkilometres, followed by their coastal and sub-coastal fauna and flora. This alsocreated new pathways or brought small, sub-continental groups of islandsnear, like the Italian Peninsula, the northern Balkans, Sicily, northern Africa,

26

Paleo-geography of Mediterranean in Würmian. Brown: exposed areas; pale blue: sea; green: large ice covers

Mediterranean characteristics. “Mediterranean” refers to the climate, not tothe geographical position. In Italy, the islands, the western coasts of Liguriaand Calabria, the Ionian coasts and Apulia have a Mediterranean climate.Coasts of the Po Plain have a cooler climate (mean annual temperature of 12°-13°C) with little, but regular rainfall in summer. The upper Adriatic has thereforea temperate mid-European climate, and the Marches, Abruzzi and Molise havea transitional climate which becomes Mediterranean only in Apulia. These cli-matic characteristics determine the type of flora, fauna and vegetation, butthere are also local features. As regards beaches, they are influenced by seathermoregulation, which becomes warmer in summer and releases heat inautumn and winter. Waters which had cooled in winter, absorb heat in springand summer, giving rise to a temperate coastal climate. This effect is clearlyperceived along the Adriatic coast, which is not very deep, closed on threesides, and tends to overheat during the summer.

■ Phytogeography

The floristic elements of the Mediterranean are similar to those of nearby con-tinents (Africa and Eurasia) and associated with western or eastern migrationsand intense, local speciation (autochthonous element). There are manyendemic species, according to Quèzel and others, about 25% of the flora. The situation on beaches and dunes is different, as there are few continentaland endemic groups. Most species are associated with past floristic connec-tions with the east and west.The western element is constituted by widely distributed species of theAtlantic coasts or associated with ocean flora. These species moved to theMediterranean during the late Messinian, when the Strait of Gibraltar opened.Although there is no proof of this, Ammophila arenaria, Elymus farctus,Euphorbia paralias and Calystegia soldanella seem to belong to this group. Butbiologically, every species is different. Euphorbia paralias and Calystegia sol-danella are found also on the Atlantic coasts, their seeds or rhizomes are eas-ily carried by the current, and their direct migration is possible. Ammophila isclearly associated with the west, as this species is found both on the Mediter-ranean and Atlantic shores, but not on those of the Red Sea or Indian Ocean.This species is not associated with other groups of shore grasses, but withlarge, desert grasses. Instead, Elymus belongs to a group usually found inAsian deserts, which spread towards the Atlantic coasts and then returned tothe Mediterranean, as the gradual increase in its chromosome numbersshows. It may be a good example of post-Messinian immigration.

29■ The present bioclimate

All Italian beaches and dunes lie on the Mediterranean (there are no significantdunes inland) and the plant and animal communities of these environmentsdepend on the biogeography of the Mediterranean, although they have differentbiogeographical problems. The biogeographical Mediterranean area is defined according to its climaticcharacteristics: mean annual temperature between 14° and 18°C, more or lessabundant rainfall (400-900 mm, locally exceeding 1500 mm) during the winter,and 2-5 dry months in summer. Mean temperatures are never below 0°C, withoccasional snow or frost. These characteristics are suitable for evergreenspecies, which can photosynthesize also in winter and reproduce in beachenvironments. These are the prevailing conditions throughout the Mediter-ranean area, and may be found also in other areas of the world, such as Cali-fornia, central Chile, southern Africa, and western and southern Australia. As regards coastal environments in Italy, not all of them are associated with

28

Dune systems consolidated by vegetation along south-western Sardinian coastline

ranean representative of Fucaceae(brown algae, widely distributed alongAtlantic coasts). Both species areclosely associated with life in tidal envi-ronments. However, these ecologicalconditions have not caused speciationin the beach flora. Actually, beachplants are always located above hightide level and avoid the consequencesof this phenomenon, otherwise remark-able in some animal groups. There are a few autochthonous ele-ments of beach and dune flora, andalthough many psammophilous specieslive in the Mediterranean, none of themseem autochthonous to Italian beachenvironments. This contrasts with rupe-stral flora, the many endemic species ofwhich live in restricted coastal areas, particularly the genus Limonium (plumba-go family), but there are also representatives of completely different groups(such as Anthyllis, Antirrhinum, Centaurea, Dianthus, Erodium, Helichrysum,Primula, etc.). Instead, the few species endemic to beaches and sand dunes inItaly are the result of differentiations of continental elements, e.g., Centaureatommasinii and Silene colorata. Despite these limitations, sandy shore flora ispeculiar, in that no marine sand species may be found in continental environ-ments, and very few continental species survive on beaches. Flora of sandybeaches is therefore unique. This is particularly evident along the coastline,where marine environments are particularly selective. Proceeding landwards,continental elements often found on sand dunes prevail where the sea influenceis hardly felt. Therefore, beach flora and vegetation are not, as is often thought,differentiations of continental flora caused by the sea influence, but are usuallycomposed by completely different species. They originated in areas far from thesea (often far from the Mediterranean), and colonized areas between continentalenvironments and the sea. Beach vegetation is therefore a kind of diaphragm, aninterface linking marine and continental environments. In conclusion, highly specialized flora of beaches, which differs completelyfrom continental flora, may be considered a mark of biodiversity. This type offlora is the result of more or less uniform processes in the Mediterranean,which did not give rise to large micro-evolutions of single groups or areas.

31

As regards the eastern element, it is associated with the Thethys, and thereforeit is older than the Atlantic group. The most important elements are speciestypically found in brackish deserts of central Asia and the Near East, such aschenopods, members of the plumbago familiy, bean-capers and a few groupsof composites, jonquils and grasses. Their typical morphological adaptation issucculence and they are highly resistant to salinity. However, these adaptationsare not relevant with regard to beaches and dunes, as the sand of theseenvironments have low sea salt contents. This flora is typical of brackishenvironments, lagoon shores, and sometimes marginal beaches. Among theseare the chenopod Salsola kali and perhaps the crucifer Cakile maritima, which isalso found on Atlantic coasts.The flora of the Mediterranean is clearly different from that of temperate, brack-ish European lagoons, as Atlantic coasts are subject to intense tidal variationsof several metres. Instead, in the Mediterranean, tides undergo slight variations(2-3 decimetres). In Italy, the only exception is the high Adriatic, where there areremarkable differences between low and high tides (70-90 cm or more, duringsyzygial tides), which constitute a serious problem to Venice, although theycannot be compared with those of the Atlantic. These conditions affect the evo-lution of flora: in the Lagoon of Venice, there are large populations of the grassSpartina stricta (= S. maritima), an Atlantic species which is exclusive to thisarea of the Mediterranean, and among algae, Fucus virsoides, the only Mediter-

30

Saltwort (Salsola kali) Back-dune vegetation with Limonium

shore variations in both the Mediterranean and Italy, showing their poor skills atspecific differentiation.The fauna of arid, damp or brackish dunes and dune heathland is verydifferent, i.e., specialized invertebrates, such as detrivores, saprophagous,psammophilous and psammo-halophilous, or phytophagous organismsassociated with psammophilous plants. In these areas, characteristics suchas “rarity”, “small local populations”, “high trophic specialization”, “littledispersion” and “habitat fragmentation” have efficiently interacted to produceendemic organisms of restricted, fragmented or relict areas. As described inthe long chapter devoted to invertebrates, both types are interesting from thepoint of view of conservation and biogeography alike, especially thosespecies colonizing southern coasts of Sicily and Sardinia or western Italy.It is extremely difficult to determine periods of penetration and isolation ofcoastal fauna in Italy. As regards beaches, zoographical historians are often sur-prised by unexpected active and passive dynamics of many species or genera,the presence of which in Italy is certainly due to specific paleogeographical orpaleoclimatic events. It is therefore worth indicating only significant fauna, whichwas certainly affected by these specific phenomena. Obviously, a few excep-tions may become the rule when dealing with large numbers. In Italy, mostcoastal fauna is recent, influenced by the Quaternary paleoclimatic events. Shore environments (sandy ones in particular) were literally “last resorts” for

33■ Zoogeography

The historical, biogeographical events and the dynamic processes which pro-duced the present beach fauna in Italy are obviously very similar to those whichoriginated plant communities, although with very different endemic species,numbers and relict populations. Faunal and floral differences may be very smallor great, according to different environments (intertidal, damp sand beach, ofdune or psammo-halophilous or psammo-hygrophilous fauna of interdunesand salicornia, etc.) and taxonomical groups, their trophic roles and speciationdegrees. Undoubtedly, most fauna living near sea-land (intertidal and damp,sandy beach fauna), despite its active dispersion, is widely distributed in boththe Mediterranean and Atlantic areas; some may even be cosmopolitan or sub-cosmopolitan. This is not surprising, because many of these organisms canwithstand large temperature variations, long exposure to sea water, and physi-ological stress. In coastal environments, they are therefore suited to move or becarried by sea currents, wind, birds or man’s activities. These are mostly eco-logically and trophically specialized elements which are exclusive to these envi-ronments, but may actively or passively disperse, or undergo metapopulationaldynamics (groups of small, local populations which are closely connected toone another and change continually: they die out locally and recolonize thesame area). In the last million years, these elements have easily adapted to

32

Pimelia grossa (darkling beetle), a typical Sicilian-Maghrebian species Sepidium siculum (darkling beetle), endemic to Sicily

3534

environmental quality may still be foundbetween Bibione and Caorle, and fromChioggia to Ravenna. Beaches extend along the Adriatic coastsouth of Rimini, to the Marches andAbruzzi, as far as the city of Pescara,but here they are narrower, restrictedinland by the railway, roads, towns andland used for growing vegetables. TheAdriatic coast also contains a wide,sandy area between Termoli and the

northern part of the Garganopromontory, the “spur” on Italy’s boot.The southern Adriatic and the Ionianhave alternating high, rocky coasts andsandy beaches. Beaches extend onlysouth of Manfredonia; then, in theremaining Apulian area, there are mainlyrocky coasts, which sometimes containnarrow dune systems, especially inSalento (see photo). Extensive dunesystems may be found between Taranto,Metaponto and Policoro (gradientsbetween 1 and 1.5%), and broadbeaches are preserved at the mouths ofthe largest rivers (Piana di Sibari, Lidi diCatanzaro). The lower Tyrrhenian inCampania, Basilicata and Calabria hassimilar characteristics, with alternatinghigh, rocky coasts and small sandybeaches (Piana di Gioia Tauro, Piana diSant’Eufemia, Golfo di Policastro) -some of these beautiful beaches areknown only locally. Moving northwards,there is the large Piana del Sele, whichstretches from Paestum to Salerno:

Beaches are again found in theSorrento peninsula, but only in a

few stretches along thevolcanic portions near

Naples. Sandybeaches dominate

from Terracinanorthwards,interruptedby a few

rockypromontories

(Circeo, Civitavecchia,Argentario, Uccellina,

Livorno, Punta Ala,Piombino). The mean

gradient tends to decreasenorthwards (1% near Viareggio).Liguria mainly has a high rocky

Paolo Audisio · Giuseppe Muscio · Sandro Pignatti

Descriptions of sandy beach systemsseldom include the dunes andheathland which compose them, asman’s harsh intervention in the pastcentury has destroyed many of them.More than 3000 of the 7500 km of theItalian coastline are composed ofbeaches used by man. In spite of this,Italian coasts do have beaches made upof beach cusps, small, almost hiddenbays, sometimes beneath rocky cliffs,near ports, or accessible only from thesea. The sandy coastline of the Adriaticstretches more or less uninterruptedlyfrom Monfalcone to the Gargano, withthe sole exception of the ConeroPromontory (Ancona) and a few areasbetween Ortona and Vasto. Thenorthern portion of this beach,interrupted by the lagoons of Grado-Marano and Venice-Chioggia,constitutes the largest Italian dunesystem, and is made up of a series ofcontinual sandy beaches from Grado toRimini. The high Adriatic beaches havelow gradients, between 0.3 and 0.7%from the coastline to the 5-m contourline, rising to 1% near the city of Pesaroand between 3 and 8% in the MonteConero area. The entire dune system is the product ofa long period of coastal stability, whichoccurred at the end of a warm climaticphase after the last glaciation. Thesystem is thought to date back to 5000years ago, when the natural subsidenceof the coast, which had started a verylong time before, was balanced by therise in sea level after the Alpine ice capmelted. In those times, the climate waswarmer than it is today, and this enabledholm oak to spread along the coasts,where it is still found today in isolatedgroups on the dunes of Mesola,

Rosolina and Bosco Nordio near S.Anna, just south of Chioggia. Later, theriver Po flooded this dune system,which today is separated from the seaby a few kilometres of land. On thedelta, the mouth of the river Po movedinland, to an area once occupied by thesea. At the same time, the sea floodedthe dunes in many areas, giving rise tolagoons.The formation of deltas and lagoons arehistorical events which are chronicled indocuments of the period. For centuries,starting from the Middle Ages, the MostSerene Republic of Venice carried outextensive hydraulic works to maintainthe Lagoon, even undertaking suchgigantic tasks as the diversion of riverswhich flowed into it and building murazzi(long seawalls) on the seaward side.These works contributed to themodelling of the shoreline, andcontinued until the 20th century. In spiteof massive human interventions, thehigh Adriatic dune system still has themost extensive beaches in Italy; inrecent years, they have been used fortourist purposes, thus bringingprosperity to an area which hadpreviously been malarial and almostdeserted, the environmental importanceof which is evident. Areas of good

Distribution of beach-dune systems in Italy

TO

AO

MI

GE

TS

TN

VE

BO

FI

AN

AQ

CB

PG

ROMA

NABA

PZ

RC

PA

CA

ROCKY COASTS

SANDY COASTS

many floristic and faunal elements which migrated during the severe climaticchanges of the Plio-Pleistocene epochs. These recurrent phenomena largelyaffected the European and Mediterranean areas, where dunes characterizelong peninsulas (like Italy) or large islands, which offered shelter during coldperiods. The combined effects of the “last resort syndrome”, falling sea levelsduring glacial periods, and wide eastward and south-westward land bridges,often caused multiple overlap of mostly xero-thermophilous fauna and flora,not only in coastal or pericoastal environments (Mediterranean or sub-Mediterranean maquis and garrigue), but also in steppe-like meadows, moor-land and brackish, sandy environments near rivers and lakes. Dune and duneheathland ecosystems as narrow “thermophilous ecological isthmuses”played an essential role during glaciations. Many halophilous, hygrophilousand moderately thermophilous organisms from northern areas, but also fromthe south-east (Balkans), and south-west (Sardinia, Corsica, Sicily, NorthAfrica) may have reached the shores by exploiting the emerging land bridges.During the Messinian and Oligocene, southern areas in Italy, such as Sicily andSardinia, were colonized by many xerophilous, psammo-hygrophilous orpsammo-halophilous elements of North African, Saharan or South-West Asianorigin, which survived and differentiated locally. These phenomena have givenrise to large numbers of specialized animals (primary and secondary psam-mophilous or psammo-halophilous organisms) in dune environments withregard to the total number of species which constitute biotic communities.

3736

coastline with a few small slopingsandy beaches (gradient 3-6%) nearriver mouths. There is then a second long stretch ofbeach along the high and middleTyrrhenian between Viareggio andPiana del Sele. Here, the coastline isdifferent from that of the Adriatic, notonly in morphology, but particularly inplant communities, which have moreMediterranean characteristics on theTyrrhenian. Among the species whichcannot be found on the Adriatic arelarge numbers of agamospecies ofLimonium (the groups L. multiforme, L.pontium, L. remotispiculum, andothers), dwarf fan palm (Chamaeropshumilis) and Anthyllis barba-jovis(Jupiter’s beard) usually found onrocky coasts. Beaches and coastalmaquis also contain species which donot colonize the eastern shores.The largest Italian islands also featurewide beaches, sometimes well-preserved but usually denselypopulated by tourists in summer. InSicily (especially in the north), coastsare high and alternate with short sandybeaches near bays and river mouths.

Distribution of beach-dune systems in Italy

The mean gradient of these beaches isbetween 1 and 2%. The once beautifuland natural beaches near Palermo,Mondello and Sferracavallo are nowlargely populated, with the exceptionof the Golfo di Castellamare. The onlylong, extensive sandy beaches whichare still of environmental importanceare those on the south-western part ofthe island, on the Canale di Sicilia(particularly those around Gela), nearSiracusa and Ragusa, and the Piana diCatania.In Sardinia, the most importantbeaches are in the west and south, onthe Golfo dell’Asinara, Golfod’Oristano and Sulcis, Poetto andQuartu, near Cagliari. Of particularbeauty are the dunes at Is Arenas (seephoto), south of Oristano, some ofwhich are higher than 10 m, and thosebetween Marina di Arbus and CapoPecora, again near Oristano. This list contains only the mostimportant sandy beaches in Italy fromthe naturalistic viewpoint, and omitsmany extensive ones used for touristpurposes, which have therefore losttheir environmental value.

Calicnemis latreillei (dynastines), a psammo-halophilous specialized species living in scattered coastal areas

■ Plants colonize beaches and dunes

It might be surprising to realize that, although beaches usually attract thosewho want to enjoy themselves, they are also extremely important from thenaturalistic point of view and constitute a small but essential feature of theItalian cultural identity. For centuries, beach flora has been studied for itspeculiar biological and ecological characteristics. In 1787, J.W. Goethe, justarrived in Venice, went to the Lido, which at the time was almost deserted, andmade his first contact with the Mediterranean beaches.On that occasion, the sight of a stranded bovine skull helped him conceive thetheory of vertebral skulls.Beaches or waterlines, in their seaward stretch, never contain vegetation.Here, sudden variations in environmental conditions make life impossible: thebeach is impregnated with salt during high tide and storms and, when the searecedes, superficial sand dries up almost completely, so that even a smallshower may wash all the salt away. Here is where debris carried by wavesaccumulates.According to the type of bottom, debris may be composed of mollusc shells,algae or seaweed such as Zostera and Posidonia. These organic remains arethen colonized by many animals which leave their “homes” quickly whenconditions change suddenly, such as marine species which climb pools andhumid sand, birds or flying insects.As regards plants, which cannot move, this environment is absolutelyinhospitable: their seeds are scattered everywhere by continual sand stir. Ifembryo plants were able to germinate, they would undergo an alternatingstress of salinity with high-tide and hot and dry conditions, with intenseexposure to the heat of the sun. These conditions are so extreme that novegetation can withstand them.This is why only fauna lives on the waterline. Landward areas above themaximum high-water line, reached only by exceptional storming waves, arecolonized by the first plant communities.

39Beach vegetationSANDRO PIGNATTI

Crucianella vegetation in Argentario (Tuscany)

41Pioneer plants. In the first strip ofbeach, usually more than 50 m fromthe coastline, vegetation is composedof ephemeral species, plants whichgerminate in autumn or late winter andlive for 1-2 months. In this period, theyflower, fructify and then dry up. In earlyJune, fruits germinate and releaseseeds, which are covered by sand andlie quiescent until autumn. The mostcommon species is the succulentCakile maritima (sea-rocket). Furtherlandwards, there are perennial grassessuch as Elytrigia (beach grass) and

Ammophila (sand reed), the dispersion of which gives rise to sand dunes.Cakile colonizes this area only occasionally, and is associated with othershort-living species like Salsola kali and beach spurges (Euphorbia peplis),which cover only 5% of the sand. At the end of their lives, only a few dry twigsremain, which are then carried away by the wind. Their seeds germinate thefollowing year, in other areas. This pioneer, totally unstable phase is enough tohinder windblown sand, which starts accumulating in certain points.

40

Elytrigia juncea

Sea-rocket (Cakile maritima)

Inland beach stretches tend to shapethemselves into mounds about 4-6metres high: dunes. Narrow beachesmay only contain piles of sandaccumulating on the banks or slopesof coastal roads, but extensive sandystretches contain dune belts which arehundreds of metres long.Visitors are immediately attracted bythem and stop to camp, but dunes arealso typical subject matter fornaturalists. The first scientific interpretation of thisenvironment came from the Frenchscientist, Kuhnholz-Lordat, whoconsidered dunes to be produced bythe interaction between wind andvegetation, constituting the so-called“dynamic binomial”. However, a thirdelement was needed - i.e., sand -because otherwise, on rockysubstrates, dunes cannot form. Wemay therefore call this the “dynamictrinomial”:

The dynamic trinomial Sandro Pignatti

Sea breezes, which blow almost everyday, carry sand inland, and thevegetation which then colonizes it isan obstacle where sand accumulatesfurther, forming dunes. When stronggales blow, the highest and mostexposed areas of dunes are erodedand their sand is carried even furtherinland - in other words, the higher thedune, the more intense the processhas been. As a sort of compensation,accumulation and erosion balancethemselves to regulate dune height.Ocean shores may have very highdunes, up to about 20-30 metres.Dunes are special environments. Sandgrains do not absorb water andtherefore plants must adaptthemselves both to little or no waterand to substrates the temperature ofwhich may be extremely high on sunnysummer days. Unlike what might beexpected, and in spite of the seanearby, the actual salt content ofdunes is very low, because the saltcarried by marine aerosol is easilywashed away by rain. Plant and animalspecies must therefore contriveadaptations if they are to survive inthese conditions.

WIND SAND VEGETATITION

DUNE

Sand reed (Ammophila littoralis)

gales usually bare the roots of Ammophila plants, which survive until newsand is accumulated and roots may start their vegetative functions again.Psammophilous vegetation develops with the creation of sand dunes. Amongbeach herbaceous plants are Medicago marina (sea Spanish clover), Calyste-gia soldanella (sea bindweed), Cyperus capitatus (beach bean-caper),Euphorbia paralias (sea spurge), Eryngium maritimum (sea holly), Echinopho-ra spinosa (Thorny sea fennel), Pancratium maritimum (sea pancratium lily),Lotus commutatus, Matthiola spp. (gillyflower), and others, which cover 50-70% of the surface.There is also a rich animal life, due to the large numbers of molluscs (especial-ly Theba pisana). Their windblown shells, together with other stranded shells,accumulate on the sides of dunes. Shells are fragmented, and the calcium car-bonate of which they are composed is eroded, enriching soils with cations. Ammophila are long-lasting, despite the continual wind variations. Seawarddunes (white dunes) are exposed to marine wind and landward ones (greydunes) are more sheltered.In the former, plants can survive only with special contrivances: Ammophila isnever completely covered by sand, because its leaves emerge from smallsand deposits; other species are annual, and depend on seed survival. Insheltered environments, even plants which germinate near the soil (chamae-phytes) may survive, although they may be damaged by sand stir. This givesrise to further vegetation variations.

43Embryo dunes. These dunes arecharacterized by Elytrigia juncea (bet-ter known as Agropyrum junceum), apsammophilous (sand-loving) peren-nial grass. Their roots cannot reachbrackish water deep in the sand, andonly the seeds which fall on dunesgerminate. Unlike Cakile and Salsola,Elytrigia produces horizontal rhizomeswhich crawl along the sand or pene-trate it. Their floral culms are 3-4 dmhigh. The pioneer phase is followed byreal colonization: this is an essentialdifference, because Elytrigia juncea islong-living and permanently occupiesthe land. Its stalks constitute obsta-cles where sand accumulates to a fewdecimetres, forming embryo dunes.Other seeds may germinate far from

brackish water, and vegetation spreads out. Also in this case, surface cover islimited to 20-30% of the total. A process of self-organization begins: vegeta-tion creates its own environment.

Dune formation. A further step in the formation of dunes is determined byanother psammophilous, perennial grass, sand reed - Ammophila littoralis (=A. arenaria).Ammophila and Elytrigia differ, although they belong to the same family.Elytrigia has isolated culms and its flabby leaves are far apart, attached to thesand surface. Instead, Ammophila has strong, erect culms, up to 1.5 m high.Its leaves are also straight, and form thick shrubs over 1 m high. This planttotally covers many square metres of surface, making it impossible todetermine if there is only one individual or many tangled up. This constitutes abarrier for windblown sand, which accumulates among the stalks ofAmmophila, increasing dune height. As stalks and leaves grow, dunes rise.The self-organizing process continues.Dunes are very unstable environments. Sand accumulates at the bottom ofAmmophila, but the steep gradients of dune sides are intensely eroded. OnTyrrhenian shores, a single, short south-westerly gale is sufficient to blowaway many decimetres of sand, which is carried to nearby dunes. These

42

Sea holly (Eryngium maritimum)

Sea camomile (Anthemis maritima)

here they are small, such as juniper, holm oak or lentisk on the southerncoasts, or Spanish broom (Spartium junceum) on the coasts of the Venetoregion. At present, these species are only occasionally found on coasts, but inthe future they may give rise to the coastal maquis or forest. Consolidateddunes of southern Italian regions also feature other leguminous shrubs, suchas the rare Retama raetam subsp. gussonei (white broom) in Sicily, or theunusual ephedra (Ephedra fragilis and E. distachya). Dunes along river mouthsthroughout Italy and its islands or near dry rivers in the south often hosttamarisk (Tamarix spp.).

Interdunal hollows. The environment of consolidated dunes is influenced bythe flow of meteoric waters towards interdunal hollows. Material moves fromthe dune top to its base: it is usually made up of fine grains and organic matterproduced by decomposed vegetal material. Water enriched with carbondioxide is slightly acid and dissolves the calcium content of sand and molluscshells which accumulate on the dunes. This is a run-off process, wherebyinterdunal hollows slowly lower and compact. Fine material (silt and clay)accumulates on the soil, and watertable waters tend to emerge by means ofcapillarity. After long periods (decades or centuries), hollows betweenconsolidated dunes become humid environments or marshes in winter. Dune and interdunal flora and fauna are completely different. Mechanicalproblems associated with sand and wind motions are absent, and the mainselective factor is the ability of roots to reach the watertable. This is whygeophytes prevail here, i.e., plants with underground rhizomes like Schoenusnigricans (bog rush), Juncus maritimus (sea rush), Juncus acutus (pungent rush)and others. Salinity, which so far had been insignificant, here constitutes aproblem. Dune plants live on rain water and therefore do not need to be salinity-resistant. Instead, interdunal plants draw water from the watertable which,being close to the sea, contains marine water. Usually it is brackish, i.e., withlow salinity, but it undergoes seasonal variations: in winter, when rain isfrequent, it is almost freshwater, but in summer, little rain and high evaporationmake brackish water emerge and salinity concentrates on the surface. Plantscontrive various defence systems against this ecological factor:- obligate halophytes (species which are exclusive to constantly low-salinityenvironments), such as Erianthus ravennae (Po cane), Holoschoenus romanus(minor rushe), Juncus maritimus, Juncus acutus, Limonium caspium, Plantagocrassifolia (succulent-leaved plantain);- halo-tolerant species (which normally live in continental environments, but aremoderately salinity-resistant), like Blackstonia serotina, Centaurium spp.,

45Consolidated dunes. Landward andAmmophila dunes are the same height,but the former are characterized bygentle slopes, with low-gradient sides.Ammophila is also present here, but itsindividuals are smaller and less thick.There are always sandy substrates,with fine soil, which compact it further.Surface cover is wider, owing to smallspecies. Windblown sand is almostabsent and erosive processes are high-ly reduced, due to the plant cover.These dunes are quite stable. On the Mediterranean coasts, theseenvironments are characterized bycrucianelletum, i.e., lignified psam-mophilous species, such as seachamomile (Anthemis maritima), Cru-cianella maritima, which gives thename to this association, and sealavender, Otanthus maritimus (= Diotismaritima). In Sardinia, there is also cliffrose (Armeria pungens). The shores ofthe high Adriatic, from Grado to Rimini,are populated by scabious, Scabiosaargentea var. alba and dogbane (Tra-chomitum venetum). Dune surfacesare often carpeted with the moss Tor-tula ruraliformis and some lichens: thiscryptogamic vegetation grows duringthe winter, when sand is more humid,and may cover the surface completely.Also annual species are widespreadand flower beautifully in spring, e.g.,Ononis variegata (variegated resthar-row) and Silene colorata.It is worth noting that consolidateddunes may occasionally contain ligni-fied plants, usually shrubs or trees, but

44

Variegated restharrow (Ononis variegata)

Sea lavender (Otanthus maritimus)

Ephedra (Ephedra sp.)

47

Epipactis palustris (helleborine), Gentiana pneumonanthe (gentian), Moliniaaltissima (grass), Phragmites australis (ditch reed), Plantago cornuti (Cornutplantain) and Schoenus nigricans. In this environment there are also many birds,which contribute to the balance of plant species.It is worth recalling here a significant event. During World War II, at San Nicolò diLido, on the Venetian coast, concrete bunkers were built and disguised underthe ammophila dunes. At the end of the war (April 1945), they were blown up,producing craters a few metres deep, at the bottom of which small brackishpools formed. In the summer of 1950, these pools had been colonized by shoresedges (Schoenoplectus littoralis), the twigs of which were higher than 1 m. Thisspecies is not restricted to coastal life and has never been found on the island ofthe Lido di Venezia, although it occasionally lives at the river mouths betweenthe Piave and the Isonzo. The nearest populations were therefore about 20 kmaway. The fruit of sedges are small, round and smooth, and thus they cannot bewindblown. They could not have been carried by the current either, because theSan Nicolò pools were far from sea or freshwater. The only possible explanationfor their presence was that they had been carried by birds, because fruits canattach themselves to feathers, or even more likely, they had been digested bybirds (endozoic distribution). It was really amazing to see how this species wasable to colonize these empty niches in such a short time. Interdunal damp areas host flora of considerable ecological value, and interac-tions between species are extremely peculiar. However, these ecosystems aredisappearing quickly, as are all European humid areas.

46

As already mentioned, the ecologicalfactors hindering the establishment ofbeach plants are sand mobilitycaused by winds and difficulty infinding water, not salt.In order to understand the importanceof salt in beach environments, wemust bear in mind that sand iscomposed of much larger grains thanthose which normally make upagricultural or woodland soils.Soil has three components ofgradually smaller diameter: sand, siltand clay. Inland soils are mainlycomposed of silt and clay; those ofbeaches contain almost 100% ofsand. Although sand grains are small,they cannot form a compact masslike those of clay and silt: the mostimportant characteristic of sand isthat it remains incoherent. This is whyit is so permeable. Large quantities of salt are dissolvedin seawater (34-37%) - not onlysodium chloride, but also otherchlorides, bromides, sulphates, etc.Seawater is taken up by sand andconstitutes a salty watertable: rootsreaching it would not be able toabsorb its water because of the highosmotic pressure due to dissolvedsalt. Dune plants therefore avoid thesalty watertable and stretch theirroots horizontally along the surface,forming a thick network. Rainwater

The importance of salinity Sandro Pignatti

moistens the sand and roots ofAmmophila (see photo), and otherpsammophilous species capture itbefore it can penetrate through thesand and mix with the saltywatertable.Dune species therefore live onrainwater, like all other plants inland,and cannot exploit the enormousquantity of seawater nearby.Salt in dune environments is onlycarried by wave aerosol: near theshoreline, the air carries largequantities of water, the salt content ofwhich is very similar to that ofseawater.In Italy, swash on the waterline inbreeze conditions is restricted(although the situation may changeon ocean shores) and saltaccumulation is limited to a fewdozen metres, sometimes only a fewmetres near the waterline.This phenomenon may be enhancedby winter storms along rocky coasts,where salt may be carried 100 andmore metres above sea level. Salty water borne by aerosolaccumulates on sandy surfaces andon the plants which colonize them:the water evaporates and the saltremains in crystallized form, which isusually harmless to plants.When rain falls, salt, which is highlysoluble in water, dissolves, penetratesthe sand in a highly diluted form, anddoes not disturb the plant further.This is why dune plants are seldomdamaged by salt. And this is also why plants ininterdunal hollows, which draw waterdirectly from the brackish watertable,are suited to a completely differentenvironment to that of dune plants.

BEACH AGROPYRUM AMMOPHILA SCABIOUS INTERDUNAL HOLLOWS

100

90

80

70

60

50

40

30

20

10

0

14 %

83 % 82 %

74%

59 %

65 %

26 %

37 %

24 %

18 %

Particle size of sand on dune of Punta Sabbioni, Venice. Red: fine sand (200-50µ); blue: coarse sand(1000-200µ)

■ Shore maquis and forests

Sandy beach vegetation becomes very complex in the transition area to conti-nental environments, where the surface contains lignified species. Maquis ofshrubs usually constitutes the pioneer phase, and when conditions arefavourable, it is replaced by high forest.Shrub vegetation of dunes, usually large junipers, is only found where theclimate is Mediterranean. Cortège species are also shrub-like, such as lentisk,wild olive, dwarf fan palm (Chamaerops humilis), myrtle (Myrtus communis),angustifoliate phillyrea (Phillyrea angustifolia), pungent asparagus (Asparagusacutifolius) and catbrier (Smilax aspera). Mediterranean maquis is exhaustivelytreated in another volume of this same series. Shore forests are chiefly constituted by pines, although this does not implythat beach vegetation naturally hosts pine forests. Most pines have beenplanted or kept by man. This is made evident by the type of trees: Pinus pinea,P. pinaster and P. halepensis.The first is spontaneous only in the southern Iberian Peninsula. In Italy, it isalways grown except, perhpas, in the Peloritan pine forest in Sicily. Clusterpine (Pinus pinaster) is a continental species, typical of Liguria and northernTuscany. On the dunes of the Tyrrhenian coast it is cultivated. Aleppo pine is

4948

Aleppo pine (Pinus halepensis)Cluster pine (Pinus pinaster)Stone pine (Pinus pinea)

sand granules evaporate, contributingto its dryness, and sand heats upbecause it is so arid. Here, beachesare covered with dunes and colonizedby woody species (maquis and forest).This is due to the gradual accumula-tion of fine soil (silt and clay), whichretains more water, although quanti-ties are always very small. As is well-known, sand is completely dry duringthe day, especially in summer. Rootsgrow in depth, where humidity isalways very low, but they cannot drawfrom the brackish watertable, whichwould poison them.There are varying temperatures onbeaches, as we may note in summer.Sea water near the shore may reach22°-25°C, and above the sea,temperatures are slightly higher, usually 25°-30°C. Along the waterline, thecontinual evaporation of water has a cooling effect and temperatures may belower. Proceeding landward, temperatures increase quickly, and at midday,few people can walk barefoot on the sand: soles start hurting when sandtemperature exceeds 48°-50°C. On dunes, temperatures are even higher andaround 60°C or more.The first consequence for plants lies in their difficulty in finding indispensablewater to keep their cellular metabolism active. Halophytes living on brackishlagoon mud have a similar problem, which they have solved by raising theosmotic pressure of their cellular liquids: they can absorb water from thewatertable filtering its saline content, which remains in the substrate. But thisis of no use to sand plants: if there is no water in the soil, it is impossible toabsorb it, and raising the osmotic pressure would be pointless. Here are the main adaptations sand plants have contrived to live in these dif-ficult ecological conditions.It must be clear that every plant has contrived its own adaptation, which dif-fers from any other, and of which very little is known. We can only list a fewexamples:● Succulence. A few plants have fleshy parts in which they store water, e.g.,Cakile maritima, Calystegia soldanella.

51spontaneous in warm Italian regions and islands, but is usually found in rockyenvironments. Coastal pine forests, e.g., at Palinuro and Porto Pino in Sar-dinia, are probably cultivated. Coastal pine forests are a beautiful sight but, environmentally speaking, theyare of little value if they are not spontaneous. Reafforested pine forests arecharacterized by large deposits of pine-needles which suffocate orimpoverish the undergrowth. Eventually, pines are the only species left, as asort of mono-culture. Gradual deforestation is the only means by whichmaquis species may be re-introduced in the Mediterranean area, normallycomposed of holm oak groves.On the high Adriatic coast from Ravenna to Grado, where the climate is tem-perate, broad-leaved shrubs (phillyrea, cornelian cherry, privet) graduallyreplace pines and mark the beginning of oak forests. The most complex vege-tation of landward dunes is dominated by oak: in the Mediterranean area it isholm oak (Quercus ilex) and on the Tyrrhenian and high Adriatic coasts holmoak forests mingle with common, Italian, Adriatic oaks (Quercus robur, Q.frainetto, Q. cerris).Mixed-oak forests are very beautiful environments (see the volume Wood-lands of Po Plain in this series): the most imposing individuals may be 4-5centuries old and 18-25 m high. Undergrowth flora is characterized byshrubs, but there are also many types of herbs and grasses.Holm oak forests have fewer floral species, because trees are denselypacked and their lush leaves shade the undergrowth. The chief species is theevergreen holm oak, which is usually smaller than broad-leaved species (12-20 m), but very lush in this environment. (see The Mediterranean Maquis inthis series).

■ Contrivances

In order to understand the way in which plant contrive to adapt to beach life,it is worth studying a few, very peculiar ecological aspects of this environ-ment. Its conditions may be considered extreme for plant survival, and thus,psammophytes (sand plants) must overcome stress rates which would belethal to other plants. As we have already seen, stress is not due to salinity, inspite of their closeness to the sea, but to environmental dryness and heat.Dryness is caused by the physical characteristics of sand granules whichabsorb only small quantities of rain, and only for short periods. Heat is due tothe sun, the rays of which stike the sand surface directly.These two effects are partially linked to one another: heat makes humidity in

50

Euphorbia peplis, a creeping spurge on aSicilian dune

sively hot. Examples are: Euphorbia peplis, Ononis variegata, Pseudorlayapumila (beach cocklebur), Silene colorata, Vulpia fasciculata (beach couchgrass). However, the most important adaptations are ecophysiological, i.e., theability to carry out processes in extremely arid and dehydrated conditions, ofwhich little is known.

■ Vegetation succession

Vegetation, as all living things, is an open, continually changing system, and istherefore dynamic, not static. “Succession” occurs when, according toMcCormick, “…sites are characterized by differing phytocenoses (i.e., vegetalgroups) in temporal succession”. Vegetal groups alternate in well-determined,not casual successions. Associations which usually alternate are called series(e.g., the series from Cakile cover to maquis). Beaches are a classic examplefor the study of successions: Kuhnholtz Lordat based his theory on thedynamic binomial (or trinomial) and, in the 18th century Lancisi was the firstscientist who proposed “succession” as a scientific model. The succession ofbeach vegetation is shown in the chart (see pag. 54).Although this model clearly outlines the series from Cakile cover to maquis,typical of the Mediterranean and Atlantic coasts, it is incomplete because itonly describes vegetation variations from the sea landwards. However, these

53

● Hairiness. Leaves and juvenile twigs have thick hair covers which protectplants from excessive transpiration, e.g., Medicago marina, Otanthus maritimus.● Rhizomes crawling under the sand. Roots avoid high sand temperatures,such as in grass types: Ammophila littoralis, Cyperus capitatus, Elytrigiajuncea, Sporobolus pungens. The culm base of these species is envelopedby layers of dried-leaf sheaths, and this also prevents their overheating.Echinophora spinosa, Eryngium maritimum, Euphorbia paralias and Pan-

cratium maritimum (sea pancratiumlily) have a well-developed under-ground system, although they do notbelong to the grass family. ● Coriaceous leaves. Thick cuticles andfew stomata restrict water loss throughtranspiration, as in Crucianella maritimaEryngium maritimum, Salsola kali andEchinophora spinosa.● Annuity. Short vegetative periods aretemporal, rather than morphologicaladaptations. Life is restricted to theshort winter-spring period, when itrains more often and it is not exces-

52

Thorny sea fennel (Echinophora spinosa)

Sea Spanish clover (Medicago marina) Sea pancratium lily (Pancratium maritimum)

the port. According to the maps of the period, the offshore quay projectedseawards on a 1-2 m deep bottom. After the construction of the quay, sandaccumulated on the eastern side. In 1950-52, botanical investigations revealedthat the beach had moved seawards for over 500 m, with regard to events of1937-39. Today, the beach has moved seawards for more than1 km with regardto 60 years ago. In this period, associations have indeed succeeded one anotheras shown in the chart (previous page), but in disarray, alternating actions andreactions. The diachronic model appears to be more realistic, although morecomplex, but after all, life phenomena are all complex. Plant succession isdetermined by gradual variations in substrate characteristics. When walking ondunes, we have the impression of treading uniform sand, but precise chemico-physical analyses reveal significant differences which explain the subtlevariations in this environment. This volume does not provide detailed information,but only a few data regarding the particle size of sand granules (see p. 46).Beaches without vegetation contain coarse sand (diameters between 200 and1000 µm), which is also found in the agropyrum vegetation. Marram grass growswhere sand grains are smaller; in scabious meadows and interdunal hollows,most coarse sand is replaced by fine sand, the diameter of which is less than200 µm. There are also variations in the microclimate (see chart below), and thecombination of these two factors identifies precise niches for each association.

55

beaches feature all phases contemporaneously, and there is no explanation tothe temporal succession, i.e., if succession occurs in both space (from thewaterline landwards) and time, throughout the years. The situation is muchmore complex. In order to have a clearer view of this situation, we may com-pare two models - synchronic and diachronic - which examine two differentaspects of this phenomenon:● Synchronic. Vegetation examined at a given moment, as described by thechart above.● Diachronic. Vegetation examined over years, decades or centuries; e.g.,very dynamic beach-dune systems may feature successions of different plantassociations over short periods. Actually, biological phenomena are cyclic andalso the examined succession may be related to this same model. Differenttypes of vegetation (which the synchronic model describes as fixed in theirpositions) gradually move forward with both the changing of the seasons andthe passing of time (as long as there are no natural catastrophes or humaninterventions). Eventually, there will be a new synchronic model identical to theprevious one, but resulting from a diachronic process lasting several decades. Each year, vegetation grows, germinates, fructifies, some plants lose theirleaves, others dry up completely, and the following year this cycle starts all overagain, growth, germination, etc., but slightly forward, and then on and on, plantsmove from one stage to the following, from one association to another. Theresult is the synchronic model, but the process is intrinsically diachronic: if it isexplained only synchronically, its complexity is overlooked. The phenomenonmay sometimes be seen in its diachronic series. In the early 20th century, anoffshore quay was built at Punta Sabbioni, near Venice, to avoid the silting up of

54

BEACH

40 °C39 °C38 °C37 °C36 °C35 °C34 °C33 °C32 °C31 °C30 °C29 °C28 °C27 °C26 °C25 °C24 °C23 °C22 °C21 °C20 °C

h 09 h 10 h 11 h 12 h 13 h 14 h 15 h 16 h 17 h 18 h 19

AGROPYRUM AMMOPHILA SCABIOUS

Temperature variations in a beach-dune system

Vegetation sequence in a beach-dune system

VE

GE

TAT

ION

BA

RE

BE

AC

H

CA

KIL

E

AG

RO

PY

RU

M

AM

MO

PH

ILA

CR

UC

IAN

EL

LA

AC

CU

MU

LA

TIO

N

AC

CU

MU

LA

TIO

N

AC

CU

MU

LA

TIO

N

ER

OS

ION

VEGETATION

WIND ACTION

AC

CU

MU

LA

TIO

N/E

RO

SIO

N

110 species of beach flora nearVenice. Analyses include biologicalforms (i.e., adaptations to inclementweather) and chorological types (geo-graphical distribution of species). Thedistribution of both biological formsand chorological types varies greatlywith regard to all Italian flora. Asregards biological forms, beaches aremostly colonized by annual and grassspecies with underground organs.The largest group is composed ofperennial grasses. Chorotypes are more complex: thereare many Mediterranean (southern)species in both Italy and Venice, butthere are few northern species onbeaches, although they are wide-spread in Italy. Instead, there aremore western and eastern species onbeaches than throughout Italy.

57■ Origin of coastal flora

Evidence shows that coastal flora is very old: similar groups and adaptationsmay be found on both sides of the northern Atlantic Ocean, Europe and NorthAmerica, suggesting that this vegetation already existed in the Tertiary, whenfloristic exchange between the two continents was still possible. Some casesare debated, e.g., the group Elymus farctus s.l. (including similar genera suchas Agropyrum, Elytrigia, Eremopyrum) concentrates in sub-desert areas ofcentral Asia, and several subspecies are distributed along the Atlantic andMediterranean shores. Chromosomes reveal that the Atlantic type is ancestraland the Mediterranean species is the last result of this group’s evolution. Also Ammophila have differing subspecies on Atlantic and Mediterraneancoasts, although here it might be a group of western origin. It is more difficultto reconstruct the history of Juncus litoralis, which is closely related to J. acu-tus, a halophilous species usually found on saline soils. Instead, J. litoralis istypical of interdunal hollows with brackish soils. It has long been consideredendemic to Italy (as J. tommasinii) and elsewhere confused with J. acutus. These examples confirm that Mediterranean beach flora is quite recent, dat-ing back to the Messinian - about 5 million years ago - and associated withthe continual variations in sea level during glaciations.Beach flora does not feature many species: on the right, charts represent the

56

Percentage of biological components in beachflora. Left: Venice; right: Italian floraPale blue: annual species; pink: grasses withunderground rhizomes; yellow: perennialgrasses; green: dwarf shrubs; brown: shrubsand trees.

PIONEERINGVEGETATION

AGROPYRUM AMMOPHILA SCABIOUS INTERDUNALHOLLOWS

INTERDUNALHOLLOWS

COASTALWOODLAND

100

80

60

40

20

01

90

49

35

26

16 15

310

15

49

61

10

1 1 1 1

70

12 2

Pungent rush (Juncus acutus)Variations of biological components in beach succession at Venice. Pink: annual grasses; blue: shrubsand trees

Percentage of chorotypes in beach flora. Left:Venice, right: Italian floraPale blue: western species; pink: southernspecies; yellow: eastern species; green:northern species; brown: Eurasian species;orange: cosmopolitan and exotic species.

■ Life on sandy shores

As already mentioned in the previous chapters, animals find it hard to live insandy shore environments. There are many stress factors which affect thesurvival of coastal zoocenoses, among which the most important are:● Mobile substrates which vary in time and space: they are composed ofwindblown sand which frequently covers small animals and their possiblefood resources.● Substrate aridity in dunes and exposed beaches, particularly duringsummer, whereby sand granules cannot keep meteoric humidity, howeverrestricted.● Beaches and sandy dunes lack nutrients, and therefore cannot providefood for the small communities of primary producers and consumers.● Saltiness both as salinity of water circulating or being absorbed by soils,damp sand and deposits of marine organic matter, and chloride contents,which are dissolved in the lower troposphere by means of marine aerosol orcrystallize on soils after surface dehydration, until rain dilutes or washesthme away. ● Intense exposure to the sun, particularly in summer, combined with lowthermal capacity surfaces, i.e., easily overheated and quickly cooled;coastal zoocenoses undergo temperature stress and circadian temperaturevariations. ● High windiness and exposure to storms, which frequently and continuallymove many animals both sea- and landwards, away from their naturalmicrohabitats. This increases their mortality rates and hampers repro-duction.● Typical fragmentation of these coastal habitats, for both natural (differenttypes of shores) and man-produced reasons, as well as their characteristicposition which stretches along a single axis, parallel to the sea/land line.These conditions complicate the reproduction and diffusion of manyspecies, particularly small and highly specialized ones, which cannotdisperse actively and tend to die out locally. However, other abiotic factors

59Sandy shores and their animalsPAOLO AUDISIO

Footprints of a wild rabbit (Oryctolagus cuniculus) on dunes at Pachino (Sicily)

particularly to areas near river mouthsor broad sea plains covered byPosidonia.Posidonia spheroids are produced bythe shredding of fibrous leaf residueswhich envelope the large rhizomes;when they fall off, they float on theexposed beach backwash andgradually form light brown, spherical oroval felty masses technically calledphytobezoars. These conditions aresuitable for large and differing animalspecies, especially invertebrates.● The already mentioned protectionlongitudinal bars and beaches offerto terrestrial organisms which arepassively or almost passively carriedover stretches of sea by currents,winds and floods during storms and exceptional meteorological phenome-na. This has enabled many species to spread and adapt themselves tobeach, dune and lagoon environments in Italy, even if they originally camefrom far away (e.g., North Africa). On beaches near river mouths, afterspring and autumn floods, large numbers of terrestrial and aquatic inverte-brates are carried seawards and stranded on nearby shores, where theyshelter under stranded vegetal debris for a few days or weeks. Particularlyeuryecious species may sometimes survive for long periods and evenreproduce on the spot, thus integrating with the local coastal biocenoses.However, most of these “castaways” die or actively and gradually disperseinland.Many biologists have noticed that sandy shore and desert environments arevery similar. Actually, resistance to high temperatures during the day andthe ability to move on mobile, windswept substrates poor in nutrients areadaptations shared by both habitats.It is also worth noting that, however negative salinity might be (which onlyaffects damp areas near the waterline or landward heathland periodicallyflooded by the sea), other factors, such as the circadian and annual mitigat-ing action of the climate, predictability of microclimates and foodresources, more extended vegetal covers and higher humidity, all makebeach environments less hostile than desert ones.

61facilitate animal life, mitigating the usually difficult conditions andcontributing to the development of biotic communities, such as:● The great thermal capacity of sea water, which mitigates summer aridityand high temperatures, but also cold winter conditions, enabling many ani-mals to reach atypical latitudes both south- and northwards, owing to thefavourable and stable temperatures of the coastal microclimate. Forinstance, many thermophilous species of the Mediterranean area mayactively penetrate shores in northern Italy, relying on the thermo-regulatinginfluence of the sea, although they would not survive in continental areas,where winters are colder. Likewise, mesophilous and hygrophilous organ-isms of central European plains (which colonized these areas during coldperiods of the recent Quaternary) may still survive at low latitudes in Italyand its islands, particularly at the mouths of perennial rivers, where theybenefit both by summer thermo-regulation of sea water and hygro-regula-tion of river mouths themselves. ● The influence of sea motion, storms and river floods, which carry largeamounts of various organic matter (however intermittently and unpredictably),

60

Accumulated posidonia spheroids (phytobezoars)

Posidonia rhizomes

■ Animal adaptations to sandy beach environments

Many sand- and dune-loving invertebrates have contrived special eco-etho-logical adaptations to difficult and particular macro- and microclimate condi-tions of sandy beach environments. Typical adaptations deal with the fre-quently excessive exposure to the sun, e.g., many species have developedenhanced burrowing activities in suitable substrates (damp sand, soil-sand,silty sand), usually associated with other contrivances and morphologicalchanges in their burrowing organs - front legs in arthropods. Other animalshave shifted their circadian activities to the night (particularly in summer). Afew diurnal sand-loving species (e.g., acridid orthopterans), which are particu-larly suited to the warm and dry microclimate of sunburnt dunes, need to par-tially or totally burrow themselves in the sand during the night, both to hamperthe effects of lowering temperatures, escape nocturnal predators wanderingacross dunes. Many less thermophilous species shift their annual reproductivecycles to winter-spring or autumn, alternating them with long estivation peri-ods (i.e., diapause or total inactivity during warm periods); others take advan-tage of daily or annual sheltering places or food resources and wanderbetween the waterline and dunes in search of food. Many species have con-trived systems to avoid contact with overheated surfaces, such as long, taper-

63■ Food chains of sandy beach habitats

Before analysing zoocenoses of sandy beach environments, we will examinefood relationships which link animals with other elements of coastal ecosys-tems. The figure below sketches the main connections between animals, plantsand soil microorganisms in hypothetical beach-dune habitats. Relationshipsare simplified with the interconnection of three main food chains. The first foodexchange occurs between sea and land environments along the waterline, andis associated with marine organic matter which is stranded on shores and con-stitutes one of the primary food resources for the entire ecosystem. Proceedinglandwards, the structure becomes more complex as dune vegetation diversifiesand is closely associated with stable soils. The strip of land from the waterlineto dune heathland is characterized by terrestrial food exchange and is associ-ated with incursions of large predators (birds and mammals) which regularly oroccasionally patrol beaches and dunes in search of stranded organic matterand small invertebrates which typically live in this area. Essential recycling oforganic matter is provided by remains of phytophagous organisms - sometimeslarge biomasses such as pulmonate molluscs and their calcareous shells -which supply the soil with nutrients and minerals.

62

D U N E S

M A I N L A N D

B E A C H

PREDATORS

DETRIVORES

LITTER

S E A

GRAZERS

DUNE VEGETATION

BU

RIE

D R

OO

TS

INTERSTITIAL FAUNA

MARINE DEBRIS · INTERTIDAL INVERTEBRATES

Accumulation of calcareous shells of Theba pisana

ing legs and fast walking; insects fly swiftly and skim surfaces (to elude strongsea winds) or, if they have lost their flying skills, they become brachypterous orapterous (i.e., their supporting wings partially or totally disappear). Many dunebeetles have more or less spherical bellies and large cavities under their wing-cases which have thermo- and hygro-regulating functions. Many of theseadaptations are identical to those of many invertebrates and small eremic(related to deserts) vertebrates which have evolved in similar ways to with-stand climatic and water strains and adapt to substrates. Many terrestrialarthropods (particularly insects) have contrived special adaptations to halobi-ous conditions, i.e., physiological modifications of their excretory organs, tosurvive in highly saline environments which are normally hostile or inacces-sible to non-specialized organisms. Other animals have resorted to simpletegumentary adaptations (waterproof hairs and bristles, waxy coatings, etc.)which protect wings and other delicate parts from the effects of partial or totalimmersion in sea water. Many small dipterans and beetles of various familiesare practically dry when leaving the water. Another common adaptation iscryptic behaviour or colouring, i.e., animals’ ability to blend with the back-ground through colour matching or shading. Typical are small yellow, white,grey and black alternating spots, which perfectly mimic the colour of the sandcolonized by these species.

■ Types of habitats and zonation of animal communities associated withsandy beaches

Let us now analyse the main types of habitats and zoocenoses of sandy beachenvironments.These are peculiar habitats, which include both marine benthic and terrestrialor freshwater organisms which live between sea and land. Populations willtherefore have a double, overlapping origin, with terrestrial and freshwateranimal species (of stationary, watertable and interstitial waters) which haveadapted to brackish water and withstand immersions in the sea or burrow insalty debris, and sea benthic, interstitial animals which have adapted tobrackish water and withstand exposure to the air and sun, in sufficiently dampconditions. Despite the attempts of marine biologists, it is very difficult todistribute the heterogeneous group of coastal organisms in planes or zones,particularly those animals which live in sandy or silty-sandy substrates, wherecommunities overlap due to both the influence of various local abiotic factorsand the considerable circadian or seasonal vagility (mobility) of many species.It is not surprising that, when treating fauna and biotic communities of shore

6564

Scarites buparius

and types of beaches. These areas contain bare sand which is onlyoccasionally splashed by exceptionally high tides or storms. These phenomenadeposit animal, vegetal or algal debris of various kinds, origins and quantitieson sandy areas of medium gradients and normally totally bare. These areasmay be divided into lower seaward and upper landward eulittorals. The formercontain most of the smallest and lightest stranded organic matter, with usuallysmall masses (between a few grams and a few hundred grams). They havetherefore restricted inertia when carried by storming waves (e.g., the laminatedleaves of marine monocotyledons, small bits of wood, pumice pebbles, etc.),together with coarser material (such as brown algae, dead sea vertebrates andinvertebrates) which are heavier and difficult to carry ashore by breakers.Instead, the upper eulittorals contain material with low specific weight, coarserand/or easily carried by currents (such as tree trunks, branches or logs carriedseaward by river floods). Sprouts of pioneer plants of supralittoral terraces areoften found in these landward areas, particularly in late winter and spring; theyare later swept away by storms or succumb to the stressful conditions ofsubstrates. In the past, marine biologists adopted the word eulittoral as asynonym of middle- and intertidal, which must not be confused with its morerecent and present meaning. Bare, sandy intertidal and eulittoral terraces

67environments, marine biologists adopt different terms to indicate the sametypes of environments, or (even more confusing) call different types ofenvironments or their different aspects by the same names. Zones are usually parallel or sub-parallel to the coastline and their width isdetermined along their orthogonal axes. We prefer the word “terrace” to“plane”, normally used by marine biologists, because “plane” regards verticalecological zonation, whereas sandy beach environments have fundamentallyhorizontal zones and small, negligible altimetric and bathymetric variations. 1. The first terrace, which is usually narrow in Italian beaches - between a fewdecimetres and a few metres - is called intertidal (or intercotidal), is constitut-ed by sandy beach and is included between the minumum level of syzygial lowand maximum syzygial high tides. In the Mediterranean, variations betweenlow and high tide are very small, about 30 cm (there are a few exceptions,such as in the Gabès Gulf in Tunisia, with 2-metre variations, or in the highAdriatic, where they locally reach 1 m), and therefore, the width of the intertidalzone depends on the gradient of the beach. The more inclined beaches are,the narrower their terraces; the flatter and more slowly degrading seawards,the wider their terraces, as in beaches of the high Adriatic. When bioclimaticand biogeographical factors are equal, animal communities of wide intertidalterraces are more stable, diversified and richer, whereas they are hardly pre-sent in narrow beaches. Intertidal communities of the English Channel andNorth Sea are more abundant and stable, because variations between highand low tide may reach a few metres and shores are flat. This area is called bymarine biologists the middle-shore (or intertidal) plane of sandy substrates.These habitats are characterized by sea-deposited organic matter which iscontinually stirred and removed by backwash or currents, and does not con-tain terrestrial vegetation. Various, elusive interstitial microinvertebrates(mesopsammon - see pp. 70-71; as already mentioned, are complex commu-nities, which are exclusive to aquatic environments, although living betweenland and sea; they are not treated in this volume) live burrowed at differentdepths in the sand. Communities which live on the surface of the intertidal ter-race, in chiefly silty-sandy habitats, are composed of burrowing animals whichlive on organic matter floating on these mobile substrates, and are usuallydrifted by tide variations.2. The second terrace, called eulittoral, covers the area between the upper,landward limit of the intertidal terrace and the lower, seaward limit of the thirdterrace, called supralittoral. The eulittoral terrace is traditionally called by Italianand European researchers the lower, seaward margin of the supralittoral zoneof sandy substrates. The width of eulittoral terraces depends also on gradients

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Zonation of animal communitiesin sandy shore environments

supralittoral belt

eulittoral belt

intertidal beach

extralittoral belt

terrace which includes the first mobile dunes, consolidated dunes, duneheathland and coastal lagoons of interdunal hollows. The first, seawardextralittoral area contains unstable, wandering white dunes which are easilymodelled by strong winds and colonized by sand reed (Ammophila littoralis). Proceeding landward are grey, consolidated dunes, which contain Crucianellamaritima, sea chamomile (Anthemis maritima), bird’s foot trefoil (Lotuscommutatus), beach lavender (Otanthus maritimus), everlasting flowers(Helychrysum spp.), Silene spp., sea scabious (Scabiosa maritima), rockrose(Cistus spp.), juniper (Juniperus oxycedrus) and sometimes ephedra (Ephedrafragilis, E. distachya), rosemary (Rosmarinus officinalis), Teucrium spp.,tamarisk (Tamarix spp.) and Ononis spp., together with other elements ofshrub-like maquis distributed on dune tops and dune heathland.Supralittoral terraces of embryo dunes and extralittoral areas of white and greyconsolidated dunes form the sandy siccalittoral terrace (from the Latin siccus,dry), which is followed by extralittoral dune heathland colonized by forests ofJuniperus phoenicea, holm oak (Quercus ilex), pines (Pinus spp.) and othermesophilous undergrowth.This volume does not treat the zoocenoses of these areas, which are usuallycomposed of hybrid, non-characterized populations of both Mediterraneanmaquis and xerophilous or mesophilous plain forests, but only describes themost frequent elements usually found on dunes.

69colonized by organisms which have adapted to usually wet, damp and baresandy beaches, may also be called sandy madolittoral terraces (from the Latinword madidus meaning wet, damp).Bare, sandy eulittoral terraces contain small invertebrates associated withstranded organic matter: “banquettes” of laminated leaves of marine phane-rogams such as Posidonia and Zostera, large brown algae remains or sea animalcarrion, wood carried down by river floods, large pebbles, pumice deposits,remains of terrestrial animals carried seawards, etc. Lower, seaward eulittoralsof the exposed beach as far as the upper, high-tide waterline frequently containsaprophagous, detrivorous invertebrates and their specialized predators. Partic-ularly near river mouths, animals stray from their usual habitats: aquatic, psam-mophilous organisms typical of rivers and continental lakes wander seawards,and psammophilous, coastal organisms penetrate sandy river banks. 3. The third terrace is called supralittoral and may be divided into two parts,one corresponding to landward-ascending sandy substrates, the other con-sisting of flat or slightly inclined silty-sandy substrates. The former may becalled the dry supralittoral of sandy beaches, corresponding to the foredune(or embryo dune) area, which contains pioneer psammophilous vegetation.This is the large sandy area between storm berms and the first dunes colo-nized by the first, sparse grasses such as sea-rocket (Cakile maritima) next tothe upper eulittoral or, landwards, sea holly (Eryngium maritimum), seabindweed (Calystegia soldanella) and beach grass (Elytrigia juncea). Breakersmight only occasionally splash these areas. The damp supralittoral with siltybeaches is characterized by silt, mud or fine, muddy sand rich in salt whichcover large, flat or low-gradient shores.Here, particularly near river mouths and coastal lagoons characterized byshrub-like vegetation, such as chenopodiaceae (Salicornia, Suaeda) andhalophilous, hygrophilous rushes (Juncus), occasional sea floods give rise tosaline or brackish pools. The supralittoral terrace of embyo dunes containsmore or less specialized phytophagous, flower-eating, indirect dune-lovingorganisms (i.e., associated with psammo-halobious plants) and psammo-halobious or ubiquitous direct dune-loving specialized detrivores and preda-tors which are also distributed in continental sand environments. The supralit-toral terrace of silty-sandy beaches is characterized by detrivores and preda-tors usually found in large coastal plains or depressions, especiallyhalophilous, mud-loving invertebrates. These communities are very similar tothose of extralittoral silty-sandy shores of damp dune heathland and coastallagoons which contain stationary brackish and freshwaters. 4. All the other landward environments are contained in the large extralittoral

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Banks of Posidonia

70 71

them prey on other microphagousmicro-organisms. The mesopsammon of intertidalenvironments and the many physical,chemical and mineralogical factorswhich affect their presence are verycomplex. The parameters which mostinfluence environmental conditions arethe particle size of soil, its mineralcontents, the mean temperature offiltering water and its salinity, quantity ofdissolved oxygen, the nature andconcentration of organic matter fromnearby rivers or watertable, theabsorption rate of sand in the variouslayers, and its relationship withexposure to sunlight at the surface.The interrelation of all these factors,particularly salinity and temperature,gives rise to the usually euryhaline andeurythermal nature of manymesopsammon organisms. They maytolerate great circadian, seasonal, orgenerally periodical variations in

dissolved chlorides and temperature.Many interstitial species migrate bothtransversally (from the sea landwards,and vice versa) and vertically (from thesurface downwards, and vice versa),according to variations in temperature,salinity and oxygen content.The strongest discriminating factors areusually the particle size of sand and itsmineral contents. Many species are onlysuited to calcareous sand, others tosilicic sand, and the size of grains andinterstices may drastically influence thepresence of characteristic organisms.Above and below particle size between0.05 and 2 mm - typical of sand - i.e.,when sand is replaced by silt, clay, orgravel, there is no mesopsammon.When the interstitial environmentcontains coarse sand andhydrogeological conditions are suitable,there are frequent exchanges andinterrelations between interstitial andother underground aquaticenvironments. Intertidal mesopsammon is oftencomposed of very interesting organismsfrom the faunistic and biogeographicalviewpoints, as the evolution of manyspecies mirrors variations occurring inthe coastline, watertable and paleo-climate, because many species live infragmented, relict areas, or haveundergone extraordinary eco-ethological and morphologicaladaptations. Analysis of the biodiversityof these organisms, which is stillincomplete, may provide an interestinginterpretation of Mediterranean andItalian coastal ecosystems. This is afurther reason for protecting beachesand underground waters from thedegradation caused by marine andfluvial pollution.

Paolo Audisio

The term mesopsammon refers to smallor very small interstitial aquatic faunawhich has adapted to life in hollows andcavities, where water is slowly filteredthrough the microscopic intersticesbetween sand grains and fine gravel.Mesopsammon may be found in anysandy accumulation, on the sea bed, inthe transition between land and sea onsandy beaches, along the banks oflakes and rivers, and even under thebottom of lakes. Although they areinvisible, these little-knownenvironments may be found almostanywhere. However, the percentages of the maintaxonomic groups change according tothe presence, in interstices, of sea- orfresh-water. In the former case, there aremainly marine groups, such asturbellarians, polychaetes, nemertinesand kinorhynchs, together with largenumbers of phyla such as cnidarians,sponges, bryozoans, molluscs, or otheramazing organisms like microscopicechinoderms and ascidians. In the lattercase, there are freshwater groups suchas oligochaetes, water-bears,gastrotrichs and water mites, togetherwith small, pre-adult stages of aquaticinsects. Both types of waters containlarge numbers of protists, especiallyciliates, nematodes and many fresh-and seawater crustaceans (especiallyharpacticoid copepods, isopods,amphipods, moustache shrimps,ostracods and others).Obviously, sandy coastal environmentscontain both types of fauna, and it is notsurprising that sand near the waterline(the intertidal belt) is usually the richestand most diversified in terms of totalnumbers of organisms, species andphyla. Almost all the animals which

compose mesopsammon share similaradaptations, such as extremely smallsize (most are between 0.1 and 0.5 mmlong), very thin, tapering, flattenedbodies (even those belonging to groupswhich usually have completely differentshapes), reduced or totally absent eyes,no pigmentation, suckers to adhere tosand grains, and other peculiarmodifications.As they all undergo similar selection(associated with their need to survive insuch particular substrates), they mayfeature extraordinarily similarmorphologies and sizes which involveboth metazoans - true multicellularanimals - and unicellular protists, likeciliates.At variance with the division of trophicroles which is typical of all animalcommunities, most mesopsammonfeed on microscopic organic debrisfiltered through sand and unicellularalgae (especially diatoms); some of

Mesopsammon

Gastrotrich of genus Thaumastoderma seenfrom beneath (photo taken by SEM [scanningelectronic microscope] )

Harpacticoid copepod of genus Amphiascus,lateral view (photo taken by SEM [scanningelectronic microscope] )

extinction. As many psammo-halophilous invertebrates are very vagile andmany populations overlap, giving rise to complex combinations (in many Italianregions which are already difficult to compare due to their different geomorpho-logical, geographical and bioclimatic situations), they are divided into threegroups for an easier description:1. Madolittoral communities include the intertidal zone of middle littorals, eulitto-rals of sandy beaches associated with stranded debris, those of landward, arid,still bare areas, and those of sandy exposed beaches as far as embryo dunes.2. Psammophilous siccalittoral communities, which are xero- and psam-mophilous organisms associated with embryo, wandering and consolidateddunes, shrubs, dune heathland maquis and sandy fossil dunes.3. Mud-loving supralittoral communities of large silty-muddy beaches (salicor-nia covers), and shore, psammophilous, mud-loving extralittoral organisms ofdune heathland and interdunal hollow lagoons.

■ Fauna: invertebrates

The three types of communities above contain invertebrates which are heredivided according to significant or well-known taxa regarding the presence ornumbers of particular genera or species which are suited to coastal habitats.In Italian regions, the recurring presence of naturalistically interesting elementsamong these guide-groups is used to outline the quality of fauna in differentareas of sandy shores and provide suggestions for the protection of singlespecies, communities and ecosystems.

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There may also be extralittoral terraces of fossil dunes (or paleo-dunes), i.e.,originally coastal beach rock which was eroded by winds and storms and movedlandward following the seaward accumulation of sediments, thus extending theoriginal coastline a few hundreds of metres or kilometres seawards. Beaches may also feature extralittoral terraces of dune heathland hollows nextto sandy, silty-sandy or muddy lagoon shores with their hygrophilous vegeta-tion. This volume only treats communities associted with sandy shores ofcoastal lagoons which are more similar to supralittoral salicornia meadows.Extralittoral animal communities of white and grey consolidated dunes arecharacterized by phytophagous species (especially rhizophagous, phyl-lophagous, and anthophilous, more or less specialized indirect dune-lovers),but there are also detrivores and predators, usually direct dune-lovers and spe-cialized psammo-halobious organisms, whereas there are only a few, occasion-al coprophagous, necrophagous and phytosaprophagous elements.Extralittoral psammophilous communities of fossil dunes include meso-xerophilous elements associated with the variable plant cover of these habitats(pine, holm oak, cork-oak forests and subcoastal, xerophilous shrubs), but alsopsammobious or direct psammophilous, variably specialized elements whichhave different trophic roles (especially saprophagous, coprophagous and rhi-zophagous).Among them are many relict elements at both ecological and geographicallevels, with a few endemic species which live in restricted areas and risk

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Dune covered with sea lavender (Otantus maritimus)

Orchestia gammarella

Talitrus saltator

Tylos europaeus

Tylos ponticus

Bledius eggs

Myosotella myosotis

Bledius graellsi

■ Communities of waterlines anddamp, sandy exposed beaches(madolittoral)

Crustaceans● Sand fleas. The European sand flea(Talitrus saltator) typically colonizes dampshores along the waterline, living in smallburrows, a few centimetre deep, in dampsand. Other typical sand fleas arecommon sand fleas (Orchestiagammarella, O. montagui,O. mediterranea, etc.) which are locallyabundant under deposits of strandedalgae and laminated Posidonia leaves.When disturbed, all halobious sand fleashop in a distinctive way on the debrisaccumulated by waves on the waterline.

7574 Invertebrates: taxonomy Paolo Audisio prey on sand fleas (particularly Talitrussaltator). During the day, they are alwaysfound under tree trunks and otherstranded woody material (in which, as wewill see later on, there may be larvae ofweevils and of the rare scarabs of thegenus Calicnemis).When night falls, their frantic nocturnalactivity - sand fleas hunt near thewaterline - begins.This species, which until a few years agowas frequently found on the Tyrrhenian,Apulian, Sicilian and Sardinian coasts, israpidly dying out due to sea pollution,which affects its biological cyclesnegatively, but particularly to continualtreading of sand and removal of largewoody residues (trunks and logs carriedby river floods which accumulate onbeaches).In Italy, this species is now rare and isonly locally found in a few Tyrrhenian(especially Tuscan) coasts which are not

visited by tourists and do not needmaintenance.Among scaritine ground beetles, typicallyfound on damp beaches, are a few smallDyschirius, especially D. numidicus, awestern Mediterranean halobiont specieswhich lives on sandy shores throughout

Eurynebria complanata

search of food, just like sand fleas. In theMediterranean, stranded debris is alsocolonized by many other saprophagousand microphagous isopods which havetypical names, such as Halophilosciazosterae, H. tyrrhena, H. ischiana,Armadilloniscus litoralis, Buchnerillolitoralis and Trichoniscus halophilus. ● Decapods. Also crabs (branchiurandecapods) are regularly found onbeaches, especially at dusk or on cloudy,rainy days. The most common andadaptable is Carcinus mediterraneus,occasionally found in intertidal terraces(middle littoral plane), but usually presenton rocky beaches and natural or artificialshores near ports or river mouths.

Coleopterans. Coleopterans are thelargest faunal group of sandy beaches,both in terms of numbers of individualsand species (at least 500 of the 12,000Italian species may be consideredexclusive, typical or characteristiccolonizers of these habitats).The normally rigid and resistantinteguments which cover them are anexcellent adaptation in these hostileterrestrial environments, aiding theanimal to survive, resist wear and tear bysand and reduce loss of water from theirbody efficiently.● Ground beetles. Among groundbeetles, the large Eurynebria complanataare the most significant indicators of thebiotic qualities of sandy beachecosystems in Italy.These coleopterans, which aredistributed in both the westernMediterranean and Atlantic sandy shoresof western Europe, typically occupylandward areas of exposed beaches(sometimes near wandering dunes) and

Actually, sand fleas sometimes move farfrom the waterline: for instance, duringthe night, Talitrus saltator may reachconsolidated dunes at tens of metresfrom the sea, exploiting an interestingastronomical system of orientation.● Isopods. Sand fleas often live withother burrowing crustaceans, such asthe isopod Tylos europaeus and similargenera. They colonize beachesaccording to their particle size andsandy-gravelly incoherent material.Tylos europaeus, which is distributedin European-Mediterranean areas, isfound where sand is fine, whereasT. ponticus lives under pebbles andcoarser sand. During the night, thesecrustaceans wander towards dunes in

Sand fleas

Italy, and Parallelomorphus laevigatus (inthe past called Scarites laevigatus).These are medium-sized scaritines (16-22 mm) associated with goodenvironmental quality beaches, wherethey live near damp waterlines (lowereulittorals). They walk on beaches evenin daytime, preying on sand fleas,particularly Eurynebria complanata.Another carabid which typically lives onAtlantic and Mediterranean waterlines isthe now rare and localized Cylinderatrisignata, which in the past was moreabundant on Italian shores, particularlynear river mouths and smallwatercourses. The distribution area andpopulations of these swift predators ofhalophilous arthropods have beendrastically reduced, particularly by man’sactivities, such as tourism, sandquarrying and marine pollution.Another species of tiger beetle isLophyridia littoralis, which colonizes thesame environments, but also dunes anddune heathland, as far as manykilometres inland. Its Mediterraneansubspecies littoralis is found on manyItalian shores. Hundreds of tiger beetlesof various species hunting on sandybeaches on warm spring and summerdays, performing sudden, short and

grazing flights when disturbed (Linneuscalled these beautiful coleopterans“Insectorum tigrides veloces”), is now afading memory for most naturalists andentomologists. On most Italian beaches,large populations of tiger beetles are sounusual, that they immediately attract theattention of researchers, who cannot helpcomparing this sight with memories ofonly twenty or thirty years before. Larvaeof tiger beetles, which also prey on sand-loving invertebrates, hunt burrowed insideshort, vertical tunnels in damp sand: it isnot difficult to imagine the consequencesof protracted treading by tourists or, evenworse, the passage of vehicles for thecleaning of beaches, on these organismsand their peculiar, fragile habits.Tiger beetles, just like Eurynebria,stenecious, anthropophobic predatorspecies, which are affected by evenminimal environmental changes, live inlocally quiet areas and are goodbiological indicators of coastalecosystem quality. In Italy, their fallingnumbers may now be interpreted aspopulation crashes.● Rove beetles. Sand fleas and Tylos oftenlive with small, predator rove beetles ofthe genera Cafius, Gabrius, Remus,Phytosus, Medon and Heterothops, the

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Lophyridia littoralis

most common of which is Cafiusxantholoma, which is not particularlyaffected by man’s presence. Other smallrove beetles, such as Polystomota andEmplenota, feed on halophilousdipterans, in the cocoons of which theydevelop. Just like crustaceans of thegenera Talitrus and Tylos, also a few rovebeetles burrow vertical tunnels in dampsand. Among them are a few species ofthe genus Bledius, which are less than1 cm long. The males of many speciesusually have unusual thorn-likeextensions on their pronota and heads.These species feed on microalgae, laytheir eggs in small lateral cells inside theirtunnels, and are often prey of smallburrowing ground beetles of the generaDyschiriodes (as mud-loving speciesassociated with silty environments,described in the chapter aboutinvertebrates in salicornia meadows anddune heathland). ● Hister beetles. The small, sand-lovinghister beetles are commonsaprophagous organisms of the generaHypocaccus (they are about 2 mm long).Their Italian species are often found onstranded, dead, terrestrial and marinevertebrates (especially fish), but they arealso attracted by excrementsof mammals (includingman’s). In Italy, typical,widespread species areHypocaccus rugifrons, H.brasiliensis and particularly H.dimidiatus. Large numbers ofthese coleopterans may be anuisance to sunbathingtourists, who are tormentedby their continual flying andlanding. Another specializedpsammo-halobiont hister

beetle which frequently colonizes Italianbeaches, especially stranded deposits ofmarine monocotyledons of the genusZostera, is Halacritus punctum (seedrawing), one of the smallest Italiancoleopterans (about 0.5 mm).● Hydraenid beetles. These very smallcoleopterans (1-2 mm) are typicallyfound in deposits of vegetal debrissplashed by water, (most species of thisfamily live as benthic lapidicolousorganisms in moving waters) and haveadapted to brackish and saline waters,although they are not specialized to life incoastal environments. Among them are afew Ochthebius (O. muelleri, O. virdis,O. marinus and others) and other speciesare more frequently found in salicorniameadows and on the shores of coastallagoons where they feed onphytoplankton as we will see further on.● Click beetles. In Italy, this familyincludes a few hundreds of species,mostly debris- and root-eaters. Theytypically hop by suddenly clicking theirthorax muscles. Only one nocturnalspecies, the pale yellow circum-Mediterranean pomace fly Isidus moreli,less than 1 cm long, is often found insummer under the stranded vegetal

debris on eulittoral terraces,whereas its larvae develop ongrasses roots on dunes. ● Soft-winged flower beetles.

Together with malachiids anddasytids are a large group of

coleopterans which normallycolonize flowers of grasses

and shrubs. Among speciesassociated with beaches,

the most specialized and typicalare Brachemys brevipennis,

small, black, wingless

Parallelomorphus laevigatus

vegetal debris, particularly the infrequentAmblyderus scabricollis, a westernMediterranean species found onCalabrian, Sicilian and Sardinianbeaches, where it apparently lives withthe similar A. brunneus, which isprobably endemic to Calabria and Sicily.The same vegetal and algal debris alsohosts a few Endomia, such as thecommon E. tenuicollis, which preferssun-dried deposits. ● Darkling beetles. Among specialized,detrivorous coleopterans of beaches isthe family of darkling beetles. Many of itsspecies have adapted to life in hostile,sandy environments, particularly desertor sub-desert areas, and they are usuallyfound in dunes.Italian eulittoral terraces are colonized bymany species of the small, chieflynocturnal Phaleria. Its yellowish membersshare the same area of sandy beaches,especially near stranded debris orcarrion, together with a few species ofXanthomus, such as X. pallidus, X. pellucidus and Halammobia pellucida.They live with other, diurnal darklingbeetles, like Tentyria, Pimelia and Erodius.

The supralittoral and extralittoralspecies of this family, just like sand-loving arthropods, are active at night

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and move to eulittoral terraces near thewaterline. Then, during the day, theyshelter near dunes.● Scarabs. Since most scarabs areassociated with dune environments, fewof them eat stranded sea debris. Amongthese are a few dung beetles of thegenus Rhyssemus, Psammodius andseldom, species of the generaPleurophorus, Platytomus and Diastictus,which colonize moist, sandy beachesnear river mouths.● Weevils. Three species of snout beetlesare typically found in stranded debris, theunusual Styphloderes exculptus, awestern Mediterranean species whichprefers dry algae; Mesites pallidipennis,with a peculiar, tapering, reddish body;Aphannommata filum (in the past knownas Brachytemnoides filum), the body ofwhich is equally tapering but black. Theyall live on stranded wooden debris (theyare xylophilous, i.e., they feed on wood).

Orthopterans. Most orthopterans live inlandward shore stretches, where leaf-and root-eaters feed on the moreabundant vegetation. However, a fewmay colonize damp beaches. Hundredsor thousands of locusts (both Italian andAfrican) typically “mass-drown” duringtheir frequent migration over seastretches swept by strong winds whichcarry the dead bodies of these largeinsects. They constitute an importantfood resource for birds, foxes and manysmall, zoosaprophagous invertebrates(especially coleopterans). Althoughusually found on pebbly beaches, thecricket Paramogoplistes squamiger maycolonize pebbly-sandy shores. ● Earwigs. There is only one specieswhich typically, although not exclusively,lives on stranded residues, theuncommon Labidura riparia, found inAsia, Europe and the Mediterranean (andnot, as is often thought, cosmopolitan or

Erodius siculus

coleopterans, the short elytra (wing-cases) of which are characterized by awhite spot. Their long, thin legs makethem look like ants. Although they areusually found on sandy or pebblybeaches, they may easily be washed bywater and also live in salicornia meadowsand brackish lagoons. They arewidespread in the Mediterranean. Theirrarer congenus Brachemys peragalloi,which is more colourful (with redprothorax), lives in similar environmentsbut is associated with narrower beaches(western Liguria and southern Provence)and risks extinction. Other beach-lovingspecies, usually found in stranded debrisalong eulittoral terraces are malachiidsColotes punctatus and Apalochrusflavolimbatus and the dasytidsDolichosoma lineare and Psilothrixviridicoerulea.● Antlike flower beetles. This grouptypically walks on beaches and includeslarge numbers of psammophilousspecies, many of which are exclusive tothis environment.The most common is Anthicusfenestratus, found on all sandy shores anddunes in Italy, where it wanders in searchof stranded debris and organic residues.However, like many other antlike flowerbeetles, it avoids man and its numbers aregradually falling in tourist resorts. Amongthe many Anthicus are A. brunneipennis,endemic to Sardinian and Corsicanbeaches, and the rare A. genei,widespread in the Mediterranean, buttypical of small sandy beaches of rockycoasts. The extremely long-legged genusMecynotarsus is also sand- and sea-living, like the common, very fastM. serricornis or the rare M. fausti. Otherspecies are typically found in stranded

Phaleria acuminata

sub-cosmopolitan). It colonizes sandyand pebbly marine beaches and banksof watercourses and may migrateupstream as far as inland valleys.Another earwig which is typically, but notexclusively found in stranded debris isAnisolabis maritima which, just likeParamogoplistes, prefers pebblybeaches. Both species are dying out dueto man’s activities.

Neuropterans. Many species ofneuropterans live on sandy coastal andsub-coastal environments. There are afew species the active predatory larvaeof which move seawards to damp sandand waterlines, particularly if sand is fineand beaches are not visited by man.Among them is Synclisis baetica, whichis widely distributed on Italian coasts.

Dipterans. May species of sea-lovingflies colonize sandy beaches, amongwhich are the genera Orygma andCoelopa and particularly shore flies ofthe genera Hecamede, Scatella,Ephydra, and others. This importantfamily features many salt- and sea-

loving species which are more or lessassociated with damp sand, where theirlarvae feed on microalgae. They arewidely distributed on Italian beaches,but also in coastal lagoons and marshes,salt-mines, salicornia meadows or nearriver mouths, such as Asmeringainermis, Hecamede albicans,Homalometopus albiditinctus, Ephydrabivittata, Scatella subguttata, Scatophilamodesta, etc. Other flies are typical ofwaterline habitats, like Helcomyzaustulata mediterranea and Fucelliamaritima, which usually colonize coastsof the high Adriatic.

Arachnids. In the same environments,under stranded residues, there are alsosmall, predatory false scorpions of thegenus Garypus and a few specializedhalophilous mites, such asHydrogamasus salinus. Garypusbeauvoisi is a Mediterranean speciesliving in Sardinia and recently found inareas of the northern Tyrrhenian. Itcolonizes algal and vegetal deposits andseagrasses of lower eulittoral terraces.It is one of the largest Italian falsescorpions, with a large, flat, stocky bodyabout 7 mm long. Also a few spiderstypically prey on small, sand-lovingarthropods found in stranded debris;among these are a few phylodromidae ofthe genus Tibellus, like T. macellus andT. maritimus, which are often found ongrasses of dunes and dune heathland,but also dwarf and jumping spidersOther typical inhabitants of Italianbeaches are the members of thepsammophilous and predator familyLycosidae (wolf spiders): Arctosa perita,the congeners A. personata and A.cinerea (especially near river mouths)

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Anisolabis maritima

and, in the same family, the morecommon Alopecosa febrilis, A. cursor, A.pulverulenta and Xerolycosa miniata.Most Lycosidae are thermophilous andvariably psammophilous: they burrowinvisible tunnels in the sand and areoften found in dunes and dry, sunny,sandy areas inland.The colours of Arctosa, particularlyA. perita, A. cinerea and A. personatamimic sand, their long legs enable them

to walk swiftly, and they are perfectlyadapted to life on sandy shores.

Centipedes. Also halophilous,predatory, geophilomorph centipedeslive under stranded debris, likeGeophilus poseidonis andHydroschendyla submarina, the namesof which already indicate their ecologicalpreferences. The former is found in theMediterranean as far as Somalia, thelatter is distributed in the Atlantic-Mediterranean areas as far as Sweden.In Italy, they colonize Tuscany, thePonziane Islands, Campania and islandsaround Sicily and Sardinia. Anotherinfrequent, halophilous, geophilomorphcentipede is Geophilus fucorum, whichlives in southern France, western Liguriaand northern-western Sardinia. Althoughit is sometimes found in pine and holmoak forests, it is typical of strandedbrown algae.

Arctosa perita

Hydroschendyla submarina