2008 quelônios delta_jacui_ing

155Technical – Scientific Articles Natureza & Conservação - vol. 6 - n.2 - October 2008 - pp. 157-170

Chelonians from the Delta of Jacuí River, RS, Brazil: habitats use and conservation

INTRODUCTION

Protected areas assure, at first, the preserva-tion of species within them; however, they aresubject to wild fires and other difficult to no-tice threats. Thus, depending on its size andlocation, the extinction of at least a small partof their species is inevitable (Rodrigues,2005). In Brazil, state, federal, and indigenouslands that are protected areas make up ap-proximately 23% of the country’s territory(Rylands & Brandon, 2005) and these areasare extremely important for the conservationof fauna and flora species. Brazilian laws de-vised a National Protected Areas Systemwhich, among other attributions, establishesthe creation of Environmental ProtectionAreas (EPA) and Parks. The Parks basically

aim at the preservation of natural ecosystemsof great ecological relevance and scenic beau-ty, allowing the execution of scientific re-searches and the development of environ-mental education and interpretation activi-ties, and recreation in contact with nature andecological tourism. The EPAs are usuallylarge areas, with a certain degree of humanoccupation, endowed with esthetic and cul-tural attributes that are especially importantfor the quality of life and welfare of humanpopulations. According to Act 9985, passedon July 18, 2000, they basically aim at protec-ting biological diversity, to discipline the oc-cupation process and to ensure the sustain-ability in the use of natural resources.

The Delta do Jacuí State Park was establishedin 1976 and has been historically sufferingfrom irregular settlements and environmentaldegradation. The Delta of the Jacuí River has

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Chelonians from the Delta of Jacuí River, RS,Brazil: habitats use and conservation

Clóvis Souza Bujes, Dr1

• Post-grade Program in Animal Biology – Department of Zoology, Universidade Federal do Rio Grande do Sul (UFRS)Laura Verrastro, Drª• Post-grade Program in Animal Biology – Department of Zoology, Universidade Federal do Rio Grande do Sul (UFRS)

ABSTRACT. The inventory performed in the Delta do Jacuí State Park, aiming at knowing the che-lonian fauna, its habitat, and the main threats to the species, has presented the occurrence of a speciesbelonging to the Emydidae family, Trachemys dorbigni, the Orbigny’s slider (Duméril & Bibron, 1835),and three species belonging to the Chelidae family: the spine-necked turtle, Acanthochelys spixii(Duméril & Bibron, 1835), the South American snake-necked turtle, Hydromedusa tectifera (Cope,1870), and the Hilaire’s side-necked turtle, Phrynops hilarii (Durémil & Bibron, 1835). The Orbigny’sslider was the most abundant, making up over 66% of the captured specimens. The Hilaire’s side-necked turtle made up 21% of the captured specimens, the spine-necked turtle 8%, and the SouthAmerican snake-necked turtle counted 5% of the captured specimens. The species occupied differenttypes of habitat, classified in this work as marshes, channels, sacks, rivers, irrigation channels, ricepaddies, puddles, and water holes. The destruction and fragmentation of habitat, pollution and dis-information by human populations were the main threats to chelonians in the Park.

Keywords: Testudines, human occupation, anthropic changes, conservationist education

1 [email protected]


Clóvis Souza Bujes - Laura Verrastro

gone through profound changes over the lastfifty years, due to the economic decline infishing activities, navigation, and small dairyand agricultural production. Besides, thedeposition of residues and effluents origina-ting from tanning industries in the Rio dosSinos valley contribute for pollution of a greatpart of the waters surrounding the islands(Branco-Filho & Basso, 2005).

Located in the Metropolitan Area of PortoAlegre, where the rivers Jacuí, Gravataí, Caí,and Sinos meet, the Park is composed of 30 is-lands and continental land covered withwoods, marshes, and flooded fields. It is oneof the most important wetlands in the state ofRio Grande do Sul, integrating a mosaic ofecosystems that represent an ecotone or tran-sition between the higher areas belonging tothe Central Depression and the CoastalLagoon System (Oliveira, 2002). Human oc-cupation, which began in the 18th Century,has generated a population that lives alongthe area’s rich biological diversity: approxi-mately 78 fish species (Koch et al., 2002), 24amphibian species (Melo, 2002), 210 birdspecies (Accordi, 2002), as well as endangeredspecies such as the broad-snouted caiman(Caiman latirostris) and the Geoffroy’s cat(Oncifelis geoffroyi).

Turtle populations in many parts of the worldare strongly impacted by human activities,development and urbanization. Approxi-mately two thirds of terrestrial and fresh-wa-ter turtle species in the world are listed asthreatened by the IUCN and over a third hasnot been evaluated yet (Turtle ConservationFund, 2002). Human exploitation of chelo-nian species has caused the decline of manypopulations, local extermination and even theextinction of species (Thorbjarnarson et al.,2000). Several papers mention human actionsas the main factor behind habitat destructionand fragmentation (e.g., Gibbons et al., 2000).Among the negative effects, are the fragmen-tation of genetic structure (Rubin et al., 2001),demographic consequences (Garber & Bur-ger, 1995; Lindsay & Dorcas, 2001), and mor-tality rates (e.g., by being run over by vehi-

cles, Gibbs & Shriver, 2002). However, somechelonian species can be very resilient to hu-man activities and continue to thrive in high-ly modified environments, while other wildanimals disappear (Mitchell, 1988).

Descriptive data on the status of populationsand communities might serve as a startingline for future enquires in the effects of ur-banization on organisms, so that efforts canbe thus directed into conservation of speciesand the environments they inhabit (Conneret al., 2005). In face of this fact, the presentstudy proposes the following: (1) get toknow the turtle species that occur in theDelta do Jacuí State Park; (2) describe thehabitats they occupy; and (3) identify poten-tial threats in an environment that is strong-ly changed by man.

MATERIALS AND METHODS

The Delta do Jacuí State Park (DJSP) is a pro-tected area located in the mid-eastern regionof the state of Rio Grande do Sul, Brazil(29º53’, 30º03’ S; 51º28’, 51º13’ W). The DJSPhas an area over 21,000 hectares, includingcontinental lands and 30 islands (Oliveira,2002). According to Maluf (2000), the state ofRio Grande do Sul is located in an intermedi-ary area climate-wise, between the Temperate(presenting an average temperature of 13ºCduring the coldest month) and Subtropical(presenting average temperatures between 15and 20ºC during the coldest month).According to the author, the area of studypresents climate type ST UMv (Subtropicalwith humid summers), and its average annu-al temperature is 19ºC, and an average tem-perature of 14ºC during the coldest month; apluvial precipitation of 1,309 mm, annual hy-dric deficit of 50 mm, and annual hydric ex-cess of 210 mm. The hydric regimen alter-nates drought and flooded periods, forcingthe vegetation to adapt to these conditions.Thus the remarkable presence of marshes,herein considered as permanent or temporarybodies of water, without a well determinedbasin, with indefinite contours and perimeter,and without their own sediments, presenting



abundant emerging vegetation and few openspaces (Ringuelet, 1962 apud Oliveira, 1998).Marshes present vegetation formations dom-inated by the sarandi-branco Cephalanthusglabratus (Rubiaceae), the Alligator Flag Thaliageniculata (Marantaceae), the amyrucaPsychotria carthagenensis (Rubiaceae), the es-padana Zizaniopsis bonariensis (Poaceae), the er-va-de-bicho Polygonum stelligerum (Polygonaceae),as well as a multitude of macrophytes such asthe Anchored water hyacinth Eichornia azurea(Pontederiaceae) and the elephant panicgrassPanicum elephantipes (Poaceae) which developon the banks of the sacks, the channels be-tween islands, the islands, where the currentis not strong (Oliveira, 1998).

Regarding water courses, this study took intoconsideration two types of environment: (1)permanent and (2) temporary. Permanentrefers to all environments that are kept floo-ded even during droughts, such as: densely

wooded internal marshes, channels (naturalor man-made courses of water, in which wa-ter moves connecting two bodies of water),sacks (a semi-closed environment connectedto the river by a narrow channel), and rivers.Temporary refers to all the bodies of waterthat suffer great volume oscillations, and thatin the majority of times completely dry overshort periods of time: irrigation channels(used for water transportation from the mainchannels to the rice paddies), rice paddies(environments that are similar to secondarychannels regarding water flow but usuallyshallower), puddles (small field areas thatflooded during the raining season), and waterholes (areas of sand extraction near marshesand rivers).

The chelonians were collected in three sitesinside the DJSP (FIGURE 1). The first site, theproject’s base, is located in the Pintada Island(IP). The chelonian study area was of

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Figure 1: Location of the Delta do Jacuí State Park, RS – Brazil and the sites of collection in the Fazenda Kramm (FK), FloresIsland (IF), and Pintada Island (IP).

Jacui River

Cai River

Sinos River

Gravatai River

PORTO ALEGRE

SouthAmerica

Argentina

Uruguay

Rio Grande do Sul

BRAZIL



approximately three hectares, an urban areathat included, at its center, the Mauá channel;to the north of the channel, there is a largeworking shipyard; to the south, the yard ofthe DJSP headquarters (used by the turtles asa nesting site); to the west, human edifica-tions (houses, commerce, schools) on marshesbanks and over them; and, to the east, theJacuí river (30°01’52”S, 51°15’07”W). The sec-ond site, the Fazenda Kramm (FK), is a farm-ing property located on the boundaries of theDJSP, south of the Jacuí River, in front of theCravo and Cabeçudas islands. The approxi-mately nine hectares area used for data col-lection includes marshes, rice paddies andwater holes (craters originating from illegalsand extraction) in an area of marsh vegeta-tion, next to the farm (29°58’59”S,51°18’58”W). The third site is located in theFlores Island (IF), in a six hectares area thatincludes marshes and a road (in whose banksthe chelonians nest) 200 meters from theEastern bank of the Jacuí River (29°58’48”S,51°16’22”W). The IP site is located 8.5 kilome-ters away from FK, which is located 5.3 kilo-meters away from the IF site, which, in turn,is located 5.2 kilometers away from the IPsite.

The expeditions took place from September2003 to August 2004 at the IP site; fromSeptember 2004 to August 2005 at the FK site;and from September 2005 to August 2006 atthe IF site. The sampling effort took two tothree consecutive days per week, betweenSeptember and January, and one day a weekduring the other months. In all areas, the cap-tures were manually made and using six box-traps (600 mm X 306 mm X 800 mm), whichused chicken carcasses as bait. The traps weresemi-submersed placed, at a 40-meters dis-tance from each other, along the banks and re-mained in the site for at least 24 hours. Thetraps were revised each three hours and, ateach expedition, their location was changed,aiming at the maximization of the coverage ofeach area.

After the identification, weighing, and gath-ering of biometric data were performed, each

captured turtle was individually markedwith a carving on their side shell (Cagle, 1939)and later released on the same capture site.The gender of adults was determined fromsecondary sexual characteristics, that is, posi-tioning of the cloaca in relation to the posteri-or margin of the plastron, the existence ofcavities on the plastron, and occurrence ofmelanization process.

Considerations about the threats to thespecies and their habitats in the DJSP, dis-cussed in this study were done from directobservations in the environment and throughinformal interviews with local human popu-lations.

RESULTS

208 specimens belonging to four fresh-waterchelonian species were captured: one speciesbelonging to the Emydidae family, theOrbigny’s slider Trachemys dorbigni (Duméril& Bibron, 1835) (N=137), and three speciesbelonging to the Chelidae family, the spine-necked turtle, Acanthochelys spixii (Duméril &Bibron, 1835) (N=16), the South Americansnake-necked turtle, Hydromedusa tectifera(Cope, 1870) (N=11), and the Hilaire’s side-necked turtle, Phrynops hilarii (Durémil &Bibron, 1835) (N=44) (FIGURE 2). The rela-tive abundance of these species was differentin the three collection sites (FIGURE 3).

The Trachemys dorbigni species was the mostabundant (66% of the captures). It was foundin the three areas, occupying different typesof habitats, from permanently or temporarilywet environments to environments stronglyinfluenced by human activity, such as sewerand water drainage channels in rice planta-tions and water holes (TABLE 1).

The Acanthochelys spixii represented 8% of thecaptures. The species was not recorded in thesampled channels, sacks and rivers, and itwas not captured at the IP site either (TABLE1). This turtle was recorded only in lentic wa-ter environments, such as temporary mar-shes, irrigation channels, rice paddies, water



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Figure 3: The rate of the four fresh-water turtle species captured in the Pintada Island, in the Flores Island, and in the FazendaKramm, in the Delta do Jacuí State Park, RS – Brazil. The total number of captured individuals is between brackets. Ph =Phrynops hilarii, Ht = Hydromedusa tectifera, As = Acanthochelys spixii, and Td = Trachemys dorbigni.

Figure 2: Chelonian species of the Delta do Jacuí State Park, RS – Brazil: the Orbigny’s slider Trachemys dorbigni (a), the spine-necked turtle, Acanthochelys spixii (b), the South American snake-necked turtle, Hydromedusa tectifera (c), and the Hilaire’sside-necked turtle, Phrynops hilarii (d).

A B

C D

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9

Proportional Captures

Spe

cies

Td

As

Ht

PhPintada Island (N =

Flores Island (N = 65

Fazenda Kramm (N= 74)



holes, and puddles in the FK and IF sites.

The Hydromedusa tectifera specimens werecaptured in the IP, FK, and IF sites and madeup 5% of total captures. They were not col-lected in sack and river habitats. They werefound in environments of low-flow waters of,in their majority, temporary nature, except fora specimen which was captured in thePintada Island/Mauá channel.

Phrynops hilarii (Figure 3.3D) was the secondmost abundant species. It was found in the IP,FK and IF areas, contributing with 21% of thecaptures. This species was present in all of thesampled habitats, occupying environmentsusually occupied by the T. dorbigni species.

The habitats preferentially occupied by chelo-nians were rivers, sacks and channels (of per-manent nature), rice irrigation channels, pud-dles and water holes (of provisory nature).Representative images of these habitats arepresented in FIGURE 4.

The more perceptible threats to the fauna andflora of the DJSP, including the chelonians, andsome measures that might help minimize nega-tive impacts are presented and discussed inTABLE 2. In a general way it was observed that,in the majority of cases, measures such as aware-

ness/education, vigilance, and legal liabilitywould minimize or even solve such problems.

DISCUSSION

Testudines represent the largest biomass infresh-water ecosystems (Bury, 1979; Souza &Abe, 1997, 2000) and their distribution andcommunity composition in fluvial environ-ments are affected both by biotic and abioticcomponents, often directly linked to ciliaryvegetation (Acuña-Mesen et al.,1983), co-spe-cific competition, predation, and temperature(Moll & Moll, 2004).

There is little in situ biological information(Richard, 1999) about the majority of SouthAmerican fresh-water turtle species. In Brazil,according to the SBH (2007), there are 36Testudine species distributed into eight fami-lies. In the state of Rio Grande do Sul, there areeleven species from four families: five marinespecies (two families) and six species from lim-netic environments (two families) (Lema,1994). Thus, the number of species listed in thisstudy, for DJSP, represents over 65% of thefresh-water chelonian fauna in Rio Grande doSul. Reptile inventory in the DJSP area (a not-published technical report done as part of theConsolidation of the DJSP subproject) hadrecorded just two Testudines species: Trachemys

Table 1: Distribution and number of specimens captured in permanent1 and temporary or ephemeral2 aquatic environments,categorized for the Delta do Jacuí State Park – RS, Brazil.

Environments/Species T. dorbigni A. spixii H. tectifera P. hilarii1Marshes 52 6 5 261Channels 53 0 1 101Sacks 0 0 0 01Rivers 5 0 0 12Irrigation channels 12 2 1 32Rice paddies 2 1 1 12Puddles 12 5 2 22Water holes 1 2 1 1

Total N 137 16 11 44

Threats

� Fires such as the ones that occurred in 2004 in theMarinheiros and Flores islands affected all the nestingsites of the chelonians. At the time, it was suspected thatthe population itself created fire spots in open areas andmarshes during the dry season, thus obtaining larger pas-ture areas, through the removal (“cleaning”) of the esta-blished vegetation, which was not grazed by cattle, in ex-change of new vegetation, that was more nutritious fordomestic animals.

� Extensive agriculture and resulting habitat fragmentation.

� Intensive agriculture: abusive extraction of water and ir-regular use of biocides and fertilizers.

� Marsh areas are filled in order to increase the area forhousing and cattle raising, an instance observed in theFazenda Kramm, where flooding fields and marshes werefilled with rice peels.

� Drainage of flooded areas or even prolonged drought pe-riods, which besides reducing activity can cause death ofindividuals and the drying of the eggs in the nests.

� Building of docks and verticality of banks through thebuilding of water contention walls that prevent the pas-sage of animals with semi-aquatic habits



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Figure 4: Habitats used by the chelonians at Delta do Jacuí State Park, RS – Brazil. Permanent habitats: river (a), sack (b), andchannel (c); and temporary or ephemeral habitats: irrigation channel (d), puddle (e) and water hole (f).

A

D

B

E

C

F

Table 2: Main observed threats to chelonians in the Delta do Jacuí State Park, RS – Brazil, and some recommendations or mi-tigating measures to minimize the impacts.

Recommendations or mitigating measures

� Public awareness and education about damagingchanges in the environment; improvements in vigi-lance both inside the Park and in its surrounding area,and investigation of the people responsible for envi-ronmental damages and strict application of legalmeasures.

� Creation of areas of special interest to the fauna andflora, even inside the park where they were untouched,intensifying the inspection of these areas.

� To intensify inspections and enforce Brazilian legisla-tion.

� To intensify inspections and enforce Brazilian legisla-tion.

� Inform people about the correct use of the land; pub-lic awareness about damaging changes to the envi-ronment

� Constructions that are adequate or adapted to floodedareas, which allow animals to access the water andland environment (access to nests and specimen dis-persion)

Continues



Threats

� Eutrofization because of intensive cattle raising or by or-ganic residue discharge.

� Elimination of ciliary woods.

� Animals such as dogs that prowl nesting areas, excava-ting the nests and eating eggs and hatchlings, a fact thatis also observed in Pakistan (Akbar et al., 2006), wheredogs captured adult turtles in shallow waters

� Introduction of alien species in the Park’s area (e.g., thegolden mussel Limnoperna fortunei – Manssur et al.,2003).

� Collection of specimens, specially hatchlings, for com-merce or raise as pets and/or to keep in terrariums.

� Specimens being run over on roads, especially duringbreeding period (males migrating in search of females,adult females seeking nesting sites), movement of indi-viduals between flooded areas and dispersion of youngindividuals.

� Often breeding females were mistreated by humans whowould beat or stone them.

� Use of specimens as food, which occurs especially withthe T. dorbigni e P. hilarii species. The collection of turtlesfor human consumption in the Delta region is sporadicand opportunistic. Some female P. hilarii are caught whenthey are nesting, in this instance, both meat and eggs areconsumed.

� Commerce of hatchlings, especially the Orbigny’s slider.

Recommendations or mitigating measures

� Rigorous control of water quality and the correct treat-ment of residues.

� Environmental impact studies; regeneration of nativeriparian forests.

� Keeping domestic animals locked, and not loose inmarsh and/or nesting areas.

� Monitor and control populations of theses species:evaluation of inter-specific competition; public aware-ness; species eradication campaigns.

� Public awareness and guidance; law enforcement.

� Placement of speed bumps on the roads; building ofsubterranean bypasses in the areas where there is agreater incidence of run over of individuals.

� To inform and make people aware on how to live alonganimals who do not harm human beings.

� Monitoring studies about the consumption of wild fau-na by the human population; monitor population onthe medium and long terms; public awareness aboutthe importance of the preservation of species.

� Guidance and public awareness, enforcement of thelaw.

Continuation Table 2

dorbigni and Phrynops hilarii.

All turtles in Rio Grande do Sul are aquaticand their geographic distribution is generallylimited to the presence of water in permanentor seasonal environments. Fluvial environ-ments are dynamic and diversified ecosys-tems, made up of a variety of habitats, in-cluding main channels, tributaries, floodingplains, and lakes. According to Moll & Moll(2004), each habitat might contain a certaincommunity of chelonians. Even if the speciesmay appear anywhere in the fluvial ecosys-tem, many of them specialize in one or more

habitats where they occur in higher numbersand biomass. Thus, several habitats in a flu-vial system can present similar species com-position, but the abundance status of eachspecies will differ.

Moll & Moll (2004) verified that in 14 of 19Neotropical turtle communities, the two mostabundant species make up over 75% of thenumber of captured specimens. Among thefour species, T. dorbigni was the most abun-dant (66% of the captures), followed by P.hilarii (21% of the captures), thus corrobora-ting the authors’ assertion. Both T. dorbigni



and P. hilarii behave as eurioic species, withday-time habits, easily observed during thehottest times of the day, and who regulatethermally over surfaced materials (trunks,floating vegetation, rocks, debris, and soforth). Medem (1960), Monteiro & Diefenbach(1987), Molina (1989), and Souza (1999) madesimilar comments when they studied speciessuch as the P. hilarii and P. geoffroanus.

Moll & Moll (2004) proposed that, apparen-tly, coexistence of two species from differentfamilies in the same habitat is possible be-cause there are species of fluvial turtles thatare specialist or optional. The Emydidae(considered optional fluvial turtles by Moll &Legler, 1971; Moll & Moll, 1990) have becomedominant in several rivers in regions rangingfrom Northern Mexico to Northern SouthAmerica, with the exception of small areas inCentral America, there is no specialist fluvialturtle competing for this habitat. One cannotclassify T. dorbigni and P. hilarii in this cate-gory of specialist or optional fluvial turtlesbecause, despite the apparent domination byT. dorbigni, both were species found in allsampling points (TABLE 1) and who occu-pied the most diversified habitats, both per-manent and ephemeral.

In consonance with data obtained by Richard(1999), P. hilarii was found occupying envi-ronments permanently flooded and, whenpresent in those which presented a temporarycharacter, they always were related to perma-nent habitats located nearby.

Hydromedusa tectifera (Chelidae) has presen-ted a great behavioral plasticity and resist-ance to different environmental conditions:specimens were found in sewers in the urbanarea (Pintada Island), in environments that re-ceive pesticide discharges (Fazenda Kramm),and in apparently more preserved sites (inter-nal marsh at the Flores Island). Ribas &Monteiro Filho (2002) found H. tectifera, aswell as P. geoffroanus and P. williamsi Rhodin& Mittermeier 1983 in environments withhigh degree of anthropic influence, where ri-ver pollution modifies the aquatic environ-

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ment through greater discharges of organicmaterial. According to Moll (1980), someTestudines species can be physiologically op-portunist, benefiting from special adaptationsto aquatic environment that present low oxy-gen levels. Besides, organic residues consti-tute an extra source of food, since the larvaeof several species of insects that inhabit theselittle oxygenized environments are the mainprey of these animals, often leading the indi-viduals of these populations to be bigger(Moll, 1980; Souza & Abe, 2001). The environ-ments occupied by H. tectifera in the DJSP aresimilar to those described by Lema & Ferreira(1990), who state that the species occur inlentic waters and in marshes, despite of beingfound by Ribas & Monteiro-Filho (2002) inlotic waters (creeks and brooks).

In the DJSP, the Chelidae Acanthochelys spixiiwas recorded in marsh environments andephemeral aquatic environments, such as irri-gation channel, rice paddies, water holes, anddraining ditches on rice plantations. D’Amato& Morato (1991) reported that this species isvery common in small creeks and marshesnear residential and industrial areas. Ribas &Monteiro-Filho (2002) reported that, in thestate of Paraná, the A. spixii was found inflooded areas which present abundance ofgrass and areas of temporary flooding duringthe raining season.

The species with the lowest capture frequen-cy was H. tectifera, however, it occurred in thethree sampled areas, while A. spixii presenteda slight higher capture frequency, but nonewas captured in one of the areas. Stone et al.(2005), when studying a turtle assembly inthe United States, argued that part of the dis-tribution or low capture frequency ofKinosternon flavescens might be due to sam-pling error, since that species spends a greatpart of the time summering or hibernating onland. H. tectifera uses to bury in the mud asthe places become dry, a behavior that was al-so observed during the winter, and reappear-ing in springtime (Lema & Ferreira, 1990).This habit was also verified by Bujes (2006,personal correspondence) for the A. spixii



species and might have contributed for thelow frequency estimates of occurrence andabundance relative to both species.

The species listed in this study also occupiedwater holes, a very peculiar environment re-sulting from anthropic action. At the DJSP, thewater holes are true craters, resulting from il-legal extraction of sand in a marsh area nextto the Fazenda Kramm. They are ephemeralenvironments, containing water only duringraining periods. These temporary habitatsseem to make available the biggest supply offood resources that propitiate favorable con-ditions for growth and breeding, offeringshelter and nesting areas to the species(Kennett & Georges, 1990).

Moll & Moll (2004) reported that turtle com-munities tend to be relatively poor in numberof species and usually one or two species oc-cur together in the same habitat, which mightalso be attributed to the chelonian communi-ty in the DJSP.

With the exception of Acanthochelys spixii,which is categorized as low risk/non-threa-tened (LR/NT) in the IUCN Red List (2006),chelonians in the DJSP are not listed in the na-tional lists of endangered species. However,impact caused by deforestation and pollutionin the Delta do Jacuí region might representserious risks to the survival of those species.The threats mentioned and the situations ob-served at the DJSP (TABLE 2) do not affect,for obvious reasons, just the chelonians, butalso the other species of fauna and flora. Thefrailty of turtle populations is linked to thelow recruiting rates, low population density,and habitat fragmentation. Undoubtedly,habitat changes was the gravest threat thatwas verified in the DJSP, which results in thereduction or absolute loss of environmentsnecessary to essential vital functions of seve-ral organisms, including food (Vickery et al.,2001), breeding (Heckert et al., 2003) and shel-ter (Ball, 2002). Removal of ciliary vegetationwas observed at the DJSP for building ofhouses and the building of dikes on thebanks, aiming at water contention and thus

preventing animals to access adjacent landfor dislocation and/or nesting. The increasein urbanization has shown to be responsiblefor drastic changes in many animal popula-tions, e.g. large carnivores (Reilly et al., 2003),butterflies (Collinge et al., 2003), salamanders(Willson & Dorcas, 2003), and fish (Paul &Meyer, 2001), as well as vegetation communi-ties, both on land environments (Francisco-Ortega et al., 2000) and aquatic environments(Fore & Grafe, 2002).

De la Ossa-Velásquez & Fajardo (1998) con-sidered the destruction and alteration of na-tural environments the gravest threats for thesurvival of Phrynops dahli, an endemic speciesin Colombia whose habitat almost complete-ly disappeared as result of the expansion ofthe agricultural frontier and urban develop-ment. Deforestation of riparian vegetationand the resulting alteration on the banks ofrivers might, according to Hildebrand &Muñoz (1992), have provoked the destructionof all reproductive efforts by chelonianspecies in Colombia.

Gibbons et al. (2000) considered the destruc-tion/fragmentation of habitats as the gravestthreat to biodiversity, followed by the intro-duction of alien species, environmental pollu-tion, diseases and parasitism, unsustainableusage, and changes in global climate.According to Tabarelli et al. (2004), deforesta-tion has direct and indirect effects on the re-duction of habitats of plant and animalspecies. As an example of direct effect, the au-thors mention the elimination of vertebratesdispersers of seeds, thus compromising ger-mination. Regarding the indirect ones, theymention the production of large quantities oforganic detritus that, combined to trash anddead biomass, occurring due to fragmenta-tion, leave certain regions even more suscep-tible to fires. Burke et al. (1994) suggested thatturtles might be especially vulnerable to po-pulation decline because of their breedingstrategies, which are incompatible with theexploitation and significant habitat loss.

Education is an important tool for the deve-



lopment of a posture that leads to conservationprojects, and it also is a key-element in theirsuccess, as people involved in, or affected by,the programs are informed on the need for thataction and the benefits of the program for theirpresent and their future. For Congdon et al.(1993), successful turtle management and con-servation programs would be those that recog-nize that protection is necessary in all stages ofthe organisms’ life history.

CONCLUSION

The chelonian community in the DJSP ismade up of four species that occupy differenttypes of habitat, including permanent andephemeral aquatic environments. Threats tothe survival of these species are many and areintimately related to the human presence inthe Park area. In face of the matters presentedin this study, it is evident that there is a pres-sing need for public awareness about the im-portance of chelonians and the fact that livingalong them does not harm human beings.Nevertheless, control must be intensified, asmust the enforcement of environmental legis-lation, as well as the implementation of stu-dies for in loco protection of animals and theenvironments they occupy.

AKNOWLEDGEMENTS:

We thank the Fundação O Boticário deProteção à Natureza (FBPN, ProjetoChelonia–RS 0594-20032) for financial sup-port; the Instituto Gaúcho de EstudosAmbientais (INGA), the Secretaria Estadualdo Meio Ambiente (SEMA), and the ZoologyDepartament at the Universidade Federal doRio Grande do Sul (UFRGS) for logistical sup-port; and to the staff at the Delta do JacuíState Park, especially Loiva and Clemente.And to our colleagues Flávio de BarrosMolina, PhD, and Márcio Borges Martins,PhD, for their valuable contribution in theproofreading of the manuscript.

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2008 quelônios delta_jacui_ing

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state of delta

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