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ENCYCLOPEDIA OF EARTH SCIENCES SERIES

ENCYCLOPEDIA ofCOASTAL SCIENCE

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edited by

MAURICE L. SCHWARTZ

Department of GeologyWestern Washington University, WA, USA

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SOUTH AMERICA, COASTAL ECOLOGY

Accumulation of toxins, such as those associated with algal bloomsof toxic algae, can cause mass mortalities of suspension feeders .orrender them unsafe for human consumption. This limits the potentialutilization of manl' species and creates the need for careful monitoringand management. As human impacts on coastal waters continue,blooms of toxin-producing phytoplankton could affect beach suspen-sion feeders more. This should be a focus for future studies.

Ornar Defeo and Anita de Alava

Rockyshore ecosystems in South AmericaRocky shores are important ecosl'stems along the South American coastbecause of the great diversitl' of species and economicimportance ofsome of these species, such as ol'sters, mussels, crabs, and fish. As a transi-tional ecosl'stem between terrestrial and marine enviromnents,the rockyshore can be divided into three parts. The first, upper part of the rockysubstrate is permanentll' exposed to the air (the supralittoral zone), thesecond part is onll' exposed during low tides (the intertidalor mid-littoralzone), and the third part is alwal's submerged (the sublittoral zone). Whilethe rocky substrate does not permit organisms to burrow, crevices, pits,and the accumulation of boulders create a' three-dimensional matrix.that

provides different microhabitats for manl' kinds of organisms. Most of theorganisms attach to the rock surfaces, thus providing additional micro-habitats on which other organisms mal' settk The sessile fauna on theintertidal zone is usualll' distributed in horizontal belts. of dominantspecies, giving the zone a striped appearance called zonation. In the sublit-toral zone, this distribution is much less marked and onll' some speciesshow a depth zonation (see Rock Coast Processes).

On the Atlantic side of South America, traveling along the coast fromnorth to south, rocky-shore communities first appear'in the SantaMarta area of Colombia (11 °13'N 74°14'W-ll°20'N 74°05'W). Forthemost part, the coastal mountains, part of the Sierra Nevada de SantaMarta, plunge abruptll' into the sea. However, a low and narrow rock(phl'l1ite or quartz-diorite) platform exists, at least in the bal's, whichareoften split up into small promontories and islands. The spatial distribu-tion of this communitl' was studied bl' Battastrõm (1980), j whodescribed the zonation as follows: thesupralittoral is inhabited o:ô.J.l'bl'the gastropods Littorina ziczac, Littorina angustior, Nodilittorina tuber-eulata, and Tectarius muricatus; the upper intertidal zone' has a bareappearance but is covered bl' blue-green algae and represents an impov-erished upper part of the lower barnacle-vermetid zone; the lower inter-tidal zone is anarrowzone formed bl'.barnacles (Tetraclita sp.,Chthamalus angustitergum, Megabalanus stultus) and/or. vermetids(Petaloconchus varians, Spiroglyphus annulatus); the sublittoral fringe iscovered bl' a mixture .of algae (Ralfsia expansa,..Sargassllmsp.,Laurencia papillosa, and Ectocarpus breviarticulatlls) andinvertebrates(barnacles, chitons, limpets, boring organisms, and a multitude of crabsand snails living inside the algae); the sublittoral zone is characterizedbl'.the presence of encrusting coralline algae overgrown bl' a mat ofmacrpalgae (most important are the rhodophl'ceans Amphiroa sp.,.Jania sp., Hypnea spp. Ceramium nitens, Centro ceras sp., and Lallrenciaspp.) and manl' sessile and semi-sessile invertebrates (sponges;"hornl'and scleractinian corais, the zoanthids Palythoa sp. and Zoanthus sp.,sea anemones, scattered barnacles and chitons, the gastropodsFissurel/a angusta and Acmaea spp., the bivalves Isognomon radiatusand Isognomon bicolor and the ascidians Styela canopus, Herdmaniamomus, and Pyura vittata).

ln Venezuela, rocky shores are present in the regions of Trinidad andthe Paria Peninsula (11 °N), but thel' are apparentll' poorll' studied andno literature was found describing this area. Rocky shores are absentfrom the delta of the Orinoco River to the northern coast of Brazil,where the littoral is covered bl' a mangrove formation.

A few rocky shore ecosl'stems exist along the northeastern Braziliancoast.. but hard substrates are commonll' available as sedimentary rockyfringes along the shallow coast. Algae, coral communities, and othersessile invertebrates such as sponges, tunicates, bryozoans, and cnidari-ans usualll' inhabit these fringes. One of the few granitic rocky forma-tions alreadl' studied is an intertidal and shallow sublittoral platform ofboulders and gravei at Ponta Cabo Branco, Paraíba (70S), which joinsthe fringing sedimentary reefs along the coast. These rocks form aunique ecosl'stem in the area composed of a rich sessile communitl' ofsponges (Chondrilla nueula, Haliclona sp., Tedania ignis, Halichondriasp.), tunicates (Didemnum duplicatum, Didemnum psammatodes,Polysyncraton amethysteum, Eudistoma spp.), cnidarians, macroalgas(Uiva sp., Gelidium sp.), ol'sters (Crassostrea rhizophorae) and associ-ated fauna. In the sublittoral, coraIs (Siderastrea stellata, Mussismiliahartti, lvJussismilia hispida, Montastrea cavernosa, Agaricia agaricites,

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and Porites astreoides) and the zoanthids Palythoa sp. and Zoanthus'sp.are common invertebrates.

From central Brazil (Espírito Santo, 200S) to Laguna in the south(Santa Catarina, 28°S), rocky shore enviromnents are formed bl' graniticor basaltic rock, resulting from the erosion of the border of the Serra doMar mountain chain, which lies parallel to the coastline. It is not a con-tinuous ecosl'stem, but forms more or less extended outcroppingsbetween sandl' beaches. This is the principal rocky shore ecoSl'stemalong the coast of Brazil and also the most known. The first publisheddescriptions of the communitl' appeared between late 1940s and earll'1950s (Oliveira, 1947, 1950; Joll', 1951, 1957) and since then, informationon species distributions and communities has been found through manl'species survel's and ecological studies.

The following sl'nthesis provides an overall picture of the communitl',and is based on work bl' Joll' (1951, 1957), Oliveira (1947, 1950),Nonato and Péres (1961), and Oliveira-Filho and Paula (1983). Thesupralittoral mostll' comprises bare space used bl' the periwinklegastropods L. ziczac and Nodilittorina lineolata, which are the mostcommon and characteristic organisms at the lower part of this zone.lsopod crustaceans of the genus Lygia are also very common at thesupralittoral.

The upper intertidal contains a dense belt of the barnacle Chthamalusbisinllatlls, while Tetraclita and lvlegabalanus are found lower in theintertidal zone, but are not dominant space occupiers. Below theChthamalus belt, Brachidontes solisianus is the dominant in terms ofspace used. However, in sites exposed to waves, Perna perna mussels canform dense beds in the mid and lower intertidal. More recentll',I bicolor has invaded the southeastern and southern coasts of Brazil

and is replacing B. solisianlls in some are as. The mid-intertidal zone isalso colonized bl' manl' algae, such as R expansa, E. breviarticulatus,Centro ceras clavulatum, Jania adhaerens, Acantophora spicifera, andUiva spp. On wave-exposed sites one can add Porphyra spp. (in winter),Chaetomorpha antennina, and manl' species of fieshl' macroalgae, andcoralline algae both articulated and encrusting. On the low intertidaland sublittoral the ol'ster C. rhizophorae can be abundant and commonalgal species are L. papillosa, A. spicifera, Jania capillacea, Amphiroa trag-illisima. Hypnea cervicornis, Rhodymenia pseudopalmata, and Coral/inaofficinalis. ln manl' sites along the coasts of São Paulo, Paraná andSanta Catarina, the sabelarüd poll'chaete Phragmatopoma caudata .forrns extended sandl' reefs along the low intertidal zone. In the lattertwo states, the colonial ascidian Eudistoma carolinense forms a narrowbelt below Phragmatopoma and comprises an important intertidalmicrohabitat for more than 117 species (Moreno and Rocha, 2001).Among the vagile invertebrates characteristic of the intertidal zoneare some herbivorous mollusks, such as the limpets Col/isel/a subnlgosaand Fissurella clenchi, besides the periwinkles, which can migrate downfrom the supralittoral zone; the predator whe1ks Stramonita, Pisania,and Leucozonia; and the crabs Pachygrapsus gracilis and Pachygrapsustransversus.

A dense Sargassum spp. bed usualll' marks the upper sublittoral fringeand is probabll' the most abundant macroalgae in both tropical and sub-tropical sublittoral zones. lt forms dense beds usualll' covering a thin lal'erof encrusting coralline algae, which are dominant space occupiers inmanl' sublittoral sites, especialll' at places where grazingpressure ishigh. .

The most important herbivores at the sublittoral are the urchins Arbacialixula, Echinometra luamter, Lytechinus variegatus, and Paracentrotusgaimardi; chitons; gastropod mollusks of the genera Aplysia, Astraea,and Tegula; and fish, such as damselfish (Stegastes sp.), surgeons(Acanthuridae), and parrotfish (Scaridae). Sessile invertebrates commonto the sublittoral zone are cnidarians of the genera Palythoa andZoanthus, which form large encrusting colonies, and a variety of smallarborescent hl'drozoan colonies. Sponges are also very common anddiverse-more than 120 species are known within the merell' 25 km longSão Sebastião Channel on the north coast of the State of São Paulo

(Hajdu et al., 1996). The most conspicuous bryozoan is the encrustingSchizoporella, but manl' small arborescent colonies are frequent, espe-cialll' from the genus Bugula. Common ascidians are the encrusting colo-nial didemnids and the solitarl' pyurids and stl'elids (Rodrigues et aI.,1998).

The southern coast of South American, between Rio Grande do Sul(Brazil) and Rio de Ia Plata estuary is formed basicalll' bl' a long sandl'beach of 750 km in length. Very little rocky substrate is available alongthis coast that could represent an important geographical barrier for ses-sile organisms. Close to the borderline between Santa Catarina and RioGrande do Sul (29°S), there is a small rocky outcropping formed bl' verytall vo1canic rocky structures, called Torres ("towers" in English) becauseof the height of the rocks. Artificial rocky substrates are also present,such as the rocky jetties at the entrance of Lagoa do Patos, which alsosupports a diverse encrusting communitl'.

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Very few experimental studies have been undertaken to understandthe dynamics of both intertidal and sublittoral rocky shore communitiesalong the Brazilian coast. Caging experiments showed that littorinidgrazing activity controls the abundance of microalgal populations inthe supralittoral zone (Apolinário et ai., 1999). Experimental analysisof succession on c1eared substrates in the intertidal zone revealed that

C. bisinuatus recruits more on the Brachidontes zone and prefersgranitic to basaltic substrates (Tanaka and Duarte, 1998). On the beltformed by Sargassum cymosum varo nanum in the 10w intertidal zone,succession is maintained in its earlier stages due to desiccation stresscausing widespread algal mortality during the early summer (paula andEston, 1989). Experimentally c1eared areas of the sublittoral zonerevealed that Sargassum stenophyllum was both the competi tive domi-nant with slow growth and an opportunist colonist (Eston andBussab, 1990).

South to the Rio de Ia Plata River estuary in Argentina, there areloess platforms separated from a coastal cliff of 7-8 m by sand strips.The upper intertidal is inhabited by crusts of blue-green algae, while themytilid bivalve Bachidontes rodriguezi is the dominant space occupier inthe mid-intertidal zone with densities up to 33,000 ind m -2 and an asso-ciated community of around 40 species. The cause of this dominance isnot only competitive abilities but also the absence of important preda-tors at the intertidal zone (Lopez Gappa et ai., 1990). The barnac1esBalanus amphritite and Balanus glandula are present in areas with fewerBalanus rodriguezi. The fust species appears in QuenquénHarbor(38°34'S; 58°42'W) and the second has become abundant in Mar deIPlata Harbor (38°0'S; 57°32'W) in recent years. There are no periwin-kles in the Mar dei Plata region, where they are replaced by the gastro-pod Siphonaria lessoni, which is abundant in both the intertidal andsupralittoral zones.

Community distribution in the southern region of Argentina, theChubut Province, is as follows: the supralittoral covered by various blue-green algae with the chiorophyte Enteromorpha intestinalis and the mol-lusks S. lessoni and Brachidontes purpuratus in tide pools; in the upperintertidal there is a striking absence of barnacles and the most importantinhabitant is the gastropod S. lessoni; in the mid-intertidal thereare threewell-marked belts: B. purpuratus, the coralline alga Corallinetum offici-nalis and the phanerogams Spartina montevidensis and Salicornietumambigua; the low intertidal is occupied by a mytilid belt (Mytilusedulisplatensis, Aulacomya ater, and B. purpuratus);.the sublittoral does notinclude the usual phaeophytes but instead has a wide belt of the chioro-phytes Codium fragile and Codium vermilara establishing its upper limit(Olivier et al., 1966).

Chile has an extended coast, about 2,600 miles long, which can betopographically divided into two very difIerent regions: south of Chiloé(41°29's), the coast is discontinuous, with mountains along the shorerising up to 3,000 m, comprising an eroded tectonic pattern of glaciatedand non-glaciated fjords. North of Chiloé the cCoastline is very regularand fully exposed to the prevailing winds and waves, but there aregeo-logical differences: from Chiloé up to Navidad (33°57'S) the coastalrange is made up of metamorphic shale of low elevation, from Navidadto Antofagasta (23°38'60S) it is mainly granitic rock, and north ofAntofagasta it consists of volcanic rocks with sedimentary intrusions(Stephenson and Stephenson, 1972; Santelices,1991)..

Along the southern coast of Chile, south tõ Chiloé Island, the badweather conditions and the limited access result in a lack of knowledgeabout the intertidal and sublittoral communities in these wave-exposedopen coasts. Nevertheless, community descriptions are available fromsheltered islands in the southernrnost tip of South America. Forinstance, in the Beagle Channel the supralittoral zone contains severalbands of lichens and the upper intertidal is covered bya mixture of algae(Bostrychia mixta, Hildenbrandia lecannellieri, Pilayella littoralis,Adenocystis utricularis, Enteromorpha spp., Porphyra spp.,Spongomvrpha spp.). Next, the mid-intertidal has mussels and barnac1estogether with high densities of the gastropods Acmaea, Collisella,Nacella, and Siphonaria, while the low intertidal is covered by pinkencrusting coralline algae and high densities of Nacella magelanica andNacella mytilina, with the brown alga Lessonia vadosa marking the low-est limit of the intertidal zone. The sublittoral communities of these

habitats consist of belts of kIacrocystis pyrifera in sheltered andsemi-sheltered sites (Santelices, 1991).

ln central Chile the supralittoral .inhabitants are barnac1es (Jehliuscirratus) in reduced densities, aggregations of Littorina araucana andLittorina peruviana, the algae Porphyra columbina and dark-red crustsof H. lecanellieri. The upper intertidal is covered by pure or mixedstands of chthamaloid barnac1es (Chthamalus scabrosus, J cirratus),while the mid-intertidal usually contains a belt of the musselPeru.mytilus purpuratus mixed with the algae Centroceras clavulatum,-e;-

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Enteromorpha compressa, Iridaea laminarioides, Uiva rigida, andPolysiphonia spp. (Santelices, 1991).

Towards the northern coast of Chile, this same pattern of speciesdistribution is observed for wave-exposed rocky habitats, but there is anorthward reduction in the number of belt-forming algae species.Macrocystis pyrifera disappears north of Concepción (36°49'60S) wherethe dominant algae are Lessonia trabeculata in the sublittoral andLessonia nigrescens along the sublittoral-intertidal fringe (Santelices,1991). Rocky sheltered communities have not been well studied and theonly description available is from Guiler (1959) in which the intertidalbiota in Antofagasta Bay was studied. There the rocks are shale thatforms a wide erosion platform covered by an association of Pyurapraeputialis and Corallina chilensis immediately below the barnacle belt.The lower limit of the Pyura belt might be controlled by predation bythe starfish Heliaster helianthus and Stichaster striatus. At the lowerintertidal Uivareplaces Corallina; the large barnacle Austramegabalanuspsittacus occurs in the lowest part of the Pyura belt and both organ-isms are covered by Ectocarpus conjervoides and Halopteris hordacea.Pyura chilensis is widespread along the coast of Chile and do not formbelts as P.praeputialis in Antofagasta region (Santelices, 1991).

Much experimental work has been done to examine species distribu-tions in both the intertidal and sublittoral zones of the Chilean coast.P. praeputialis, for instance, maintains its dense intertidal beds byintraspecific self-facilitating mechanisms that enhance recruitment tothe border of previously settled individuais (Alvarado et ai., 2001). Theintertidal rocky community in Mehuin (39°25'60S), in the southerncoast, is regulated by herbivory and competition; there are apparentlyno intertidal carnivores capable of controlling herbivore densities andhigh herbivore densities can destroy the red alga Iridaea boryana cover;depending on the season of the disturbance, the community may bedominated by the alga or by barnacles plus crustose algae (lara andMoreno, 1984). ln the sublittoral zone, experimental kelp canopyremoval revealed that M. pyrifera control the species composition ofunderstory algal community (Santelices and Ojeda, 1984), and, in cen-tral Chile, the removal of L. nigrescens results in a community of cal-careous crustose alga lvIesophyllum sp. in the presence of herbivory andlarge patches of Gelidium chilense in the absence of herbivory (Ojedaand Santelices, 1984). ln northern Chile, the abundance of herbivores,algae morphology, plant density, water movement, and the egg case ofelasmobranches which tie plant stipes together are the most importantecological factors for the persistence and stability of L. trabeculata beds(Vasquez, 1992).

A high degree of eco-geographic isolation seems to be a generalcharacteristic of the intertidal and shallow sublittoral rocky communi-ties of Chile. The result is a high degree of endemism and several of _theendemic species occupy unique ecological niches with unknown parallelsin comparable habitats elsewhere (Santelices, 1991). The causes of thisisolation, and factors limiting the distribution of these species and com-munities are unknown and offer an important area of future research.

Oceanographic conditions and upwelling are strong infiuences on thecoastal communities of Peru. This upwelling area associated withhigh1y productive waters stretches from 4°8 southward to 400S, in cen-tral Chile, but the most intensive effects are seen in the Peruvian coast,especially during the winter (Tarazona and Arntz, 2001). Because of theupwelling process, intertidal and shallow sublittoral zones of northernChile and Peru have high species diversity. ln Peru, the forest-formingkelps (Lessonia spp. and M. pyrifera), the mussel Argopecten purpuratus,the gastropod Thais chocolata, the crabs Cancer setosus, Cancerporteri,and Platyxanthus orbignyi, and the sea urchin Loxechinus albus alloccur in great numbers with a large biomass. Kelp forests form a sublit-toral belt about 15 m wide and harbor numerous associated species.Mussels (Perumytilus purpuratus, Semimytilus algosus) also form beds inthe intertidal zone, with more then 70 associated species. The structureof these communities tends to be controlled by grazers and predators,while the population dynamics of the algae Macrocystis is infiuenced bythe upwelling and EI Nino events (Tarazona and Arntz, 2001). As anexample of this infiuence, the intense EI Nino event of 1982-83 causedmass mortality of key species like the musseJ Semimytilus and brownalgae (Macrocystis and Lessonia) along the Peruvian rocky shores(Tarazona et ai., 1988).

ln Colombia, the tectonic processes along the Pacific coast have givenorigin to abundant steep cliffs (>45° slope) and rocky shores with moregently sloping platforms, composed of boulders, pebbles, and graveifrom cliff erosion. Along the northern coast and in the interior ofBuenaventura Bay (3°52'60N), species have the following distributionalpatterns: desiccation-tolerant blue-green and green algae, a lichenspecies, periwinkles (Austrolittorina aspera, Littoraria zebra), the crabGrapsusgrapó1./S,and the isopod Lygia baudiana inhabit the supralittoral.

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SOUTH AMERICA, COASTAL ECOLOGY

About 20 species occupy the upper intertidal zone, among them theperiwinkle L. zebra, the crab Paehygrapsus transversus on less wave-exposed eliffs, .while bamaeles (TetraeUta, Chthamalus), limpets(Fissurellidae, Acmaeidae, Siphonariidae), crabs (G. grapsus) and somegreen algae occur on exposed eliffs. The mid-intertidal zone is dominatedby bivalves (Braehidontes sp., Isognomidae, and oysters) and the associ-ated fauna is comprised by crabs of the families Xanthidae (Eriphiasquamata) and Grapsidae (P transversus), and the red coralline algaLithothamnion. In the lower intertidal zone it is possible to find bama-eles, anemones, sponges, the gastropods Aeanthina brevidentata andThais kiosquiformis, and some crabs. At this levei an increasing numberof boring organisms (bivalves of the families Pholadidae, Petricolidae,and Mytilidae and the ghost shrimp Upogebia tenuipollex contribute tothe bioerosion of the rocky eliffs. Erosion rates can be as much as 300cm3 m-2month-1 for igneous rocky eliffs and 450 cm3 m-2 month-I forsedimentary rocky clifts (Cantera and Blanco, 2001).

The most important stresses on rocky shores are the trampling effectsof tourists and fisherman, oil and sewage pollution, and selective col-lecting for food and obtaining mussel seeds for cultures. AlI theseprocesses have been studied in different rocky shore ecosystems andshowed marked infiuences in the intertidal community structure.Although many rocky shore ecosystems are located in protected areasinside ecological reserves, usually the goal of the reserve is to protecteither the terrestrial or the underwater ecosystem while neglectingthe intertidal zones. One of the few well-studied reserves is the EstaciónCostera de Investigaciones Marinas (ECIM) in Las Cruces (33°30'S),Chile, with a 5 ha human-exelusion exposed shore established in 1982.The intertidal community changes and food-web .cascading effects,which occurred inside the reserve, showed that humans act as an effi-cient and selective keystone predator (Castilla, 1999).

The rocky shore communities throughout the South Arnerica coastsare reasonably well described. Yet, almost no information exists on thePatagonian coast of Argentina and the Ecuadorian coast. On the otherhand, mechanisms of community structure are best studied in Chileand, very recently, BraziL Apparently, the conservation of rocky shoreshas not been of primary importance for most countries environrnentalconservation policies. The few well-monitored known marine reservesare located in Chile.

Rosana Moreira da Rocha

Coral reefs ecosyst~ms in S.outhAmericaCoral reefs are highly diverse ecosystems that have been compared with thetropical rain fores!. They are formed by coelenterates that secrete a calciumskeleton aswell asby other calcium secreting organisms such as mollusks,corallinae algae, and sponges (see Coral Reefs). The structure formed bythese organisms offer shelter and support for an incredible diversity of life,making coral reefs crucial to the culture and livelihood of millions of peo-pie in tropical coastal environrnents. Corals have on their living tissue sym-biotic algae called zooxantelae that contribute with oxygen and organiccompounds and receive protection from the coral colony. The phenomenaknown as' bleaching is caused when the zooxantelae leaves thecora!, .usuallydue to stress related causes. ln the last decades, mass bleaching events thathave caused the death of many coral reefs have been reported from severalparts of the world. These events, related to climate change, have added toother anthropogenic stresses, which are causing an alarming rate of degra-dation of coral reefs. The concems with the health and conservation of

coral reefs have led govemment and organizations to establish several pro-grams for monitoring and protecting these ecosystems. The Global CoralReef Monitoring Network (GCRMN) was established in 1995 with theobjective of encouraging and coordinating monitoring of coral reefs at thegovernrnent, community, and research levels around the world. Brazil,Colombia, and Venezuela are part of the Node of GCRMN for southemtropical America, together with Panama and Costa Rica (Wilkinson,2000).

Coral reef formations in tropical South America are more developedin the Atlantic coast, as several important cold upwelling areas inhibitreef development in the Pacific coas!. Coral reef formations on thePacific side are found in a few reef patches on the coast of Colombiaand on offshore islands. The Atlantic coast of South America is under

strong continental infiuences, which introduces large amounts of sedi-ment and inhibits the development of extensive coral reef formations insome areas, especially around large rivers such as the Amazon, Orinoco,and Magdalena. Coral reefs occur along the Atlantic coast ofColombia, Venezuela, and Brazil.

Colombia is the only South Arnerican country with both Pacific andAtlantic coasts and coral reefs. There are about 2,700 km2 of coral reefs

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in the Caribbean waters, of which 75% are located in oceanic reef com-plexes. Along the mainland coast, there are fringing reefs on rockyshores such as the Santa Marta and Urabá areas (Garzon-Ferreiraet aI., 2000).

In Venezuela, reefs occur along three Caribbean areas out of total2,875 km of Caribbean and Atlantic coastline. Along the continentalcoast of Venezuela, the more developed coral formations occur in theMorrocony National Park and adjacent reefs, where more than 30 coralspecies can be found. The best reef formations are found 100km off-shore at Los Roques Archipelago, with 57 coral species and reefsgrowing up to 50 m depth (Garzon-Ferreira et aI., 2000).

Brazil is located in the central-oriental portion of South Americawith approximately 7,408 km of coastline running from 4°25'N to33°45'S. Coral reefs are sparsely distributed along almost 3,000 km ofcoast (Maida e Ferreira, 1997), and their distribution and location isstill poorly known (Castro and Pires, 2001). Laborel (1969) provided themost thorough qualitative description of Brazilian reefs (see also Maidaand Ferreira, 1997 and Castro and Pires, 2001 for reviews). TheBrazilian coast can be divided into three biogeographical realms.Intertropical (northem coast): comprises the northem coast from theFrench Guyana border to Cabo de São Roque. Tropical: the largest por-tion of the Brazilian coast, from Cabo de São Roque to Cabo Frio, Riode Janeiro State. Subtropical: from Cabo Frio to the border withUruguay. Reef formations, ineluding some that are not true coral reefs,are present mostly along the tropical Brazilian coast (northeastemcoast), although some coral growth also occurs at the northem regionand in the southeastern coast up to São Paulo State. Coral diversity islow, with only 18 hard coral species, but 10 of these are endemic toBraziL Of those, three species have an even more restricted distribution,only occurring on the reefs of Bahia State. Brazilian reefs present onlyone species of reef-dwelling soft coral, Neopongodes atlantiea, which isan endemic form (Maida e Ferreira, 1997).

Reef formations such as those that are typical of the northeasternBrazilian coast are rare elsewhere, not displaying the distinctive zonesgenerally observed in reefs around the world (Leão et aI., 1988). One ofthe main characteristics of the Brazilian reefs, are the constructionsmade by calcareous algae, from the group of the Melobesiae, and ver-metid gastropods of the genus Petaloeonehus and Dendropoma. These .forrnations can be found on crystalline and eruptive rock, but are espe-cially common on the seaward side of sandstone banks and coral reefs.They grow in the upper part of the reef front forming structures that aresimilar to the algal ridges of the Indo-Pacific reefs (Laborel, 1969).Endemic species like Favia leptophylla, MussismiUa braziliensis,Mussismilia hartii, and Mussismilia hispida, that among the principalreef builders, are archaic forms, the remnants of a tertiary fauna thatwas preserved in a refugium provided by the seamounts of Abrolhosbank during the last glaciation (Leão et a!., 1988).

On the northem coast the main geographic feature is the immenseArnazonian estuary with a width of more than 350 km. The water of theArnazonian estuary, loaded with vast amounts of sediments, is trans-ported by littoral currents to the north up to Guyana, forming an exten-sive barrier for coral reef development. According to Laborel (1969),the region has no reefs, only scattered coral growth, but further down.the coast, about80km off São Luís, the capital of Maranhão State, laysa large coral bank called Parcel de Manuel Luis, whose existence hasbeen known to navigators since the 17th century, mostly because of thedanger it represented to navigation.

Reef formations are present along the northeastem coast from Cabodo São Roque (Rio Grande do Norte state) to the south of Bahia State.In Cabo de São Roque there is a group of oval shaped reefs located afew miles from the coast. These reefs are simple structures, usuallyformed by numerous pinnaeles in a shallow sandy base. On the reef fiatonly two species of coral occur, Siderastrea stellata and Favia gravida.Calcareous algae Melobesiaea and the vermetid gastropods form analgal ridge. The seaward crest is dominated by Millepora aleieornis,followed by ]vI. hartii on the slope and M ontrastea cavernosa at greaterdepths. According to Laborel (1969) the main reef builder in this regionis S. stellata.

In this region, from Natal to São Francisco River, the principalcharacteristics are the coas tal sandstone banks and superficial coralreefs, disposed in various lines running parallel to the coastline alongmore than 600 km. The sandstone banks and superficial coral reefsform lines that are not continuous, and in the places where these forma-tions are interrupted, the coast takes the form of small bays, normallywith mangrove swamps whenever creeks and rivers are present (Maida eFerreira, 1997). The sandstone banks are structures that can reach up to10 km in length and 20-60 m wide. They can appear directly adjacent tothe beach, or as submerged formations on the high tides (Dominguezet aI., 1990). In some areas up to three lines of reefs can be seen at onev