2008 quelônios delta_jacui_ing


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2008 quelônios delta_jacui_ing

  1. 1. Chelonians from the Delta of Jacuí River, RS, Brazil: habitats use and conservation English 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 species belonging 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’s slider 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 South American snake-necked turtle counted 5% of the captured specimens. The species occupied different types of habitat, classified in this work as marshes, channels, sacks, rivers, irrigation channels, rice paddies, 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 INTRODUCTION aim at the preservation of natural ecosystems of great ecological relevance and scenic beau- Protected areas assure, at first, the preserva- ty, allowing the execution of scientific re- tion of species within them; however, they are searches and the development of environ- subject to wild fires and other difficult to no- mental education and interpretation activi- tice threats. Thus, depending on its size and ties, and recreation in contact with nature and location, the extinction of at least a small part ecological tourism. The EPAs are usually of their species is inevitable (Rodrigues, large areas, with a certain degree of human 2005). In Brazil, state, federal, and indigenous occupation, endowed with esthetic and cul- lands that are protected areas make up ap- tural attributes that are especially important proximately 23% of the country’s territory for the quality of life and welfare of human (Rylands & Brandon, 2005) and these areas populations. According to Act 9985, passed are extremely important for the conservation on July 18, 2000, they basically aim at protec- of fauna and flora species. Brazilian laws de- ting biological diversity, to discipline the oc- vised a National Protected Areas System cupation process and to ensure the sustain- which, among other attributions, establishes ability in the use of natural resources. the creation of Environmental Protection Areas (EPA) and Parks. The Parks basically The Delta do Jacuí State Park was established in 1976 and has been historically suffering from irregular settlements and environmental 1 chelonia_rs@hotmail.com degradation. The Delta of the Jacuí River has Technical – Scientific Articles 155 Natureza & Conservação - vol. 6 - n.2 - October 2008 - pp. 157-170
  2. 2. Clóvis Souza Bujes - Laura Verrastro gone through profound changes over the last cles, Gibbs & Shriver, 2002). However, some fifty years, due to the economic decline in chelonian species can be very resilient to hu- fishing activities, navigation, and small dairy man activities and continue to thrive in high- and agricultural production. Besides, the ly modified environments, while other wild deposition of residues and effluents origina- animals disappear (Mitchell, 1988). ting from tanning industries in the Rio dos Sinos valley contribute for pollution of a great Descriptive data on the status of populations part of the waters surrounding the islands and communities might serve as a starting (Branco-Filho & Basso, 2005). line for future enquires in the effects of ur- banization on organisms, so that efforts can Located in the Metropolitan Area of Porto be thus directed into conservation of species Alegre, where the rivers Jacuí, Gravataí, Caí, and the environments they inhabit (Conner and Sinos meet, the Park is composed of 30 is- et al., 2005). In face of this fact, the present lands and continental land covered with study proposes the following: (1) get to woods, marshes, and flooded fields. It is one know the turtle species that occur in the of the most important wetlands in the state of Delta do Jacuí State Park; (2) describe the Rio Grande do Sul, integrating a mosaic of habitats they occupy; and (3) identify poten- ecosystems that represent an ecotone or tran- tial threats in an environment that is strong- sition between the higher areas belonging to ly changed by man. the Central Depression and the Coastal Lagoon System (Oliveira, 2002). Human oc- MATERIALS AND METHODS cupation, which began in the 18th Century, has generated a population that lives along The Delta do Jacuí State Park (DJSP) is a pro- the area’s rich biological diversity: approxi- tected area located in the mid-eastern region mately 78 fish species (Koch et al., 2002), 24 of the state of Rio Grande do Sul, Brazil amphibian species (Melo, 2002), 210 bird (29º53’, 30º03’ S; 51º28’, 51º13’ W). The DJSP species (Accordi, 2002), as well as endangered has an area over 21,000 hectares, including species such as the broad-snouted caiman continental lands and 30 islands (Oliveira, (Caiman latirostris) and the Geoffroy’s cat 2002). According to Maluf (2000), the state of (Oncifelis geoffroyi). Rio Grande do Sul is located in an intermedi- ary area climate-wise, between the Temperate Turtle populations in many parts of the world (presenting an average temperature of 13ºC are strongly impacted by human activities, during the coldest month) and Subtropical development and urbanization. Approxi- (presenting average temperatures between 15 mately two thirds of terrestrial and fresh-wa- and 20ºC during the coldest month). ter turtle species in the world are listed as According to the author, the area of study threatened by the IUCN and over a third has presents climate type ST UMv (Subtropical not been evaluated yet (Turtle Conservation with humid summers), and its average annu- Fund, 2002). Human exploitation of chelo- al temperature is 19ºC, and an average tem- nian species has caused the decline of many perature of 14ºC during the coldest month; a populations, local extermination and even the pluvial precipitation of 1,309 mm, annual hy- extinction of species (Thorbjarnarson et al., dric deficit of 50 mm, and annual hydric ex- 2000). Several papers mention human actions cess of 210 mm. The hydric regimen alter- as the main factor behind habitat destruction nates drought and flooded periods, forcing and fragmentation (e.g., Gibbons et al., 2000). the vegetation to adapt to these conditions. Among the negative effects, are the fragmen- Thus the remarkable presence of marshes, tation of genetic structure (Rubin et al., 2001), herein considered as permanent or temporary demographic consequences (Garber & Bur- bodies of water, without a well determined ger, 1995; Lindsay & Dorcas, 2001), and mor- basin, with indefinite contours and perimeter, tality rates (e.g., by being run over by vehi- and without their own sediments, presenting Technical – Scientific Articles 156 Natureza & Conservação - vol. 6 - n.2 - October 2008 - pp. 157-170
  3. 3. Chelonians from the Delta of Jacuí River, RS, Brazil: habitats use and conservation English abundant emerging vegetation and few open wooded internal marshes, channels (natural spaces (Ringuelet, 1962 apud Oliveira, 1998). or man-made courses of water, in which wa- Marshes present vegetation formations dom- ter moves connecting two bodies of water), inated by the sarandi-branco Cephalanthus sacks (a semi-closed environment connected glabratus (Rubiaceae), the Alligator Flag Thalia to the river by a narrow channel), and rivers. geniculata (Marantaceae), the amyruca Temporary refers to all the bodies of water Psychotria carthagenensis (Rubiaceae), the es- that suffer great volume oscillations, and that padana Zizaniopsis bonariensis (Poaceae), the er- in the majority of times completely dry over va-de-bicho Polygonum stelligerum (Polygonaceae), short periods of time: irrigation channels as well as a multitude of macrophytes such as (used for water transportation from the main the Anchored water hyacinth Eichornia azurea channels to the rice paddies), rice paddies (Pontederiaceae) and the elephant panicgrass (environments that are similar to secondary Panicum elephantipes (Poaceae) which develop channels regarding water flow but usually on the banks of the sacks, the channels be- shallower), puddles (small field areas that tween islands, the islands, where the current flooded during the raining season), and water is not strong (Oliveira, 1998). holes (areas of sand extraction near marshes and rivers). Regarding water courses, this study took into consideration two types of environment: (1) The chelonians were collected in three sites permanent and (2) temporary. Permanent inside the DJSP (FIGURE 1). The first site, the refers to all environments that are kept floo- project’s base, is located in the Pintada Island ded even during droughts, such as: densely (IP). The chelonian study area was of Sinos River Cai River Jacui River Gravatai River BRAZIL Argentina South Rio Grande do Sul America PORTO ALEGRE Uruguay Figure 1: Location of the Delta do Jacuí State Park, RS – Brazil and the sites of collection in the Fazenda Kramm (FK), Flores Island (IF), and Pintada Island (IP). Technical – Scientific Articles 157 Natureza & Conservação - vol. 6 - n.2 - October 2008 - pp. 157-170
  4. 4. Clóvis Souza Bujes - Laura Verrastro approximately three hectares, an urban area captured turtle was individually marked that included, at its center, the Mauá channel; with a carving on their side shell (Cagle, 1939) to the north of the channel, there is a large and later released on the same capture site. working shipyard; to the south, the yard of The gender of adults was determined from the DJSP headquarters (used by the turtles as secondary sexual characteristics, that is, posi- a nesting site); to the west, human edifica- tioning of the cloaca in relation to the posteri- tions (houses, commerce, schools) on marshes or margin of the plastron, the existence of banks and over them; and, to the east, the cavities on the plastron, and occurrence of Jacuí river (30°01’52”S, 51°15’07”W). The sec- melanization process. ond site, the Fazenda Kramm (FK), is a farm- ing property located on the boundaries of the Considerations about the threats to the DJSP, south of the Jacuí River, in front of the species and their habitats in the DJSP, dis- Cravo and Cabeçudas islands. The approxi- cussed in this study were done from direct mately nine hectares area used for data col- observations in the environment and through lection includes marshes, rice paddies and informal interviews with local human popu- water holes (craters originating from illegal lations. sand extraction) in an area of marsh vegeta- tion, next to the farm (29°58’59”S, RESULTS 51°18’58”W). The third site is located in the Flores Island (IF), in a six hectares area that 208 specimens belonging to four fresh-water includes marshes and a road (in whose banks chelonian species were captured: one species the chelonians nest) 200 meters from the belonging to the Emydidae family, the Eastern bank of the Jacuí River (29°58’48”S, Orbigny’s slider Trachemys dorbigni (Duméril 51°16’22”W). The IP site is located 8.5 kilome- & Bibron, 1835) (N=137), and three species ters away from FK, which is located 5.3 kilo- belonging to the Chelidae family, the spine- meters away from the IF site, which, in turn, necked turtle, Acanthochelys spixii (Duméril & is located 5.2 kilometers away from the IP Bibron, 1835) (N=16), the South American site. snake-necked turtle, Hydromedusa tectifera (Cope, 1870) (N=11), and the Hilaire’s side- The expeditions took place from September necked turtle, Phrynops hilarii (Durémil & 2003 to August 2004 at the IP site; from Bibron, 1835) (N=44) (FIGURE 2). The rela- September 2004 to August 2005 at the FK site; tive abundance of these species was different and from September 2005 to August 2006 at in the three collection sites (FIGURE 3). the IF site. The sampling effort took two to three consecutive days per week, between The Trachemys dorbigni species was the most September and January, and one day a week abundant (66% of the captures). It was found during the other months. In all areas, the cap- in the three areas, occupying different types tures were manually made and using six box- of habitats, from permanently or temporarily traps (600 mm X 306 mm X 800 mm), which wet environments to environments strongly used chicken carcasses as bait. The traps were influenced by human activity, such as sewer semi-submersed placed, at a 40-meters dis- and water drainage channels in rice planta- tance from each other, along the banks and re- tions and water holes (TABLE 1). mained in the site for at least 24 hours. The traps were revised each three hours and, at The Acanthochelys spixii represented 8% of the each expedition, their location was changed, captures. The species was not recorded in the aiming at the maximization of the coverage of sampled channels, sacks and rivers, and it each area. was not captured at the IP site either (TABLE 1). This turtle was recorded only in lentic wa- After the identification, weighing, and gath- ter environments, such as temporary mar- ering of biometric data were performed, each shes, irrigation channels, rice paddies, water Technical – Scientific Articles 158 Natureza & Conservação - vol. 6 - n.2 - October 2008 - pp. 157-170
  5. 5. Chelonians from the Delta of Jacuí River, RS, Brazil: habitats use and conservation English A B C D 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’s side-necked turtle, Phrynops hilarii (d). Pintada Island (N = Ph Flores Island (N = 65 Fazenda Kramm (N= 74) Ht Species As Td 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 Proportional Captures Figure 3: The rate of the four fresh-water turtle species captured in the Pintada Island, in the Flores Island, and in the Fazenda Kramm, 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. Technical – Scientific Articles 159 Natureza & Conservação - vol. 6 - n.2 - October 2008 - pp. 157-170
  6. 6. Clóvis Souza Bujes - Laura Verrastro 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. hilarii 1Marshes 52 6 5 26 1Channels 53 0 1 10 1Sacks 0 0 0 0 1Rivers 5 0 0 1 2Irrigation channels 12 2 1 3 2Rice paddies 2 1 1 1 2Puddles 12 5 2 2 2Water holes 1 2 1 1 Total N 137 16 11 44 holes, and puddles in the FK and IF sites. ness/education, vigilance, and legal liability would minimize or even solve such problems. The Hydromedusa tectifera specimens were captured in the IP, FK, and IF sites and made DISCUSSION up 5% of total captures. They were not col- lected in sack and river habitats. They were Testudines represent the largest biomass in found in environments of low-flow waters of, fresh-water ecosystems (Bury, 1979; Souza & in their majority, temporary nature, except for Abe, 1997, 2000) and their distribution and a specimen which was captured in the community composition in fluvial environ- Pintada Island/Mauá channel. ments are affected both by biotic and abiotic components, often directly linked to ciliary Phrynops hilarii (Figure 3.3D) was the second vegetation (Acuña-Mesen et al.,1983), co-spe- most abundant species. It was found in the IP, cific competition, predation, and temperature FK and IF areas, contributing with 21% of the (Moll & Moll, 2004). captures. This species was present in all of the sampled habitats, occupying environments There is little in situ biological information usually occupied by the T. dorbigni species. (Richard, 1999) about the majority of South American fresh-water turtle species. In Brazil, The habitats preferentially occupied by chelo- according to the SBH (2007), there are 36 nians were rivers, sacks and channels (of per- Testudine species distributed into eight fami- manent nature), rice irrigation channels, pud- lies. In the state of Rio Grande do Sul, there are dles and water holes (of provisory nature). eleven species from four families: five marine Representative images of these habitats are species (two families) and six species from lim- presented in FIGURE 4. netic environments (two families) (Lema, 1994). Thus, the number of species listed in this The more perceptible threats to the fauna and study, for DJSP, represents over 65% of the flora of the DJSP, including the chelonians, and fresh-water chelonian fauna in Rio Grande do some measures that might help minimize nega- Sul. Reptile inventory in the DJSP area (a not- tive impacts are presented and discussed in published technical report done as part of the TABLE 2. In a general way it was observed that, Consolidation of the DJSP subproject) had in the majority of cases, measures such as aware- recorded just two Testudines species: Trachemys Technical – Scientific Articles 160 Natureza & Conservação - vol. 6 - n.2 - October 2008 - pp. 157-170
  7. 7. Chelonians from the Delta of Jacuí River, RS, Brazil: habitats use and conservation English A B C D E F Figure 4: Habitats used by the chelonians at Delta do Jacuí State Park, RS – Brazil. Permanent habitats: river (a), sack (b), and channel (c); and temporary or ephemeral habitats: irrigation channel (d), puddle (e) and water hole (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. Threats Recommendations or mitigating measures I Fires such as the ones that occurred in 2004 in the I Public awareness and education about damaging Marinheiros and Flores islands affected all the nesting changes in the environment; improvements in vigi- sites of the chelonians. At the time, it was suspected that lance both inside the Park and in its surrounding area, the population itself created fire spots in open areas and and investigation of the people responsible for envi- marshes during the dry season, thus obtaining larger pas- ronmental damages and strict application of legal ture areas, through the removal (“cleaning”) of the esta- measures. blished vegetation, which was not grazed by cattle, in ex- change of new vegetation, that was more nutritious for domestic animals. I Extensive agriculture and resulting habitat fragmentation. I Creation of areas of special interest to the fauna and flora, even inside the park where they were untouched, intensifying the inspection of these areas. I Intensive agriculture: abusive extraction of water and ir- I To intensify inspections and enforce Brazilian legisla- regular use of biocides and fertilizers. tion. I Marsh areas are filled in order to increase the area for I To intensify inspections and enforce Brazilian legisla- housing and cattle raising, an instance observed in the tion. Fazenda Kramm, where flooding fields and marshes were filled with rice peels. I Drainage of flooded areas or even prolonged drought pe- I Inform people about the correct use of the land; pub- riods, which besides reducing activity can cause death of lic awareness about damaging changes to the envi- individuals and the drying of the eggs in the nests. ronment I Building of docks and verticality of banks through the I Constructions that are adequate or adapted to flooded building of water contention walls that prevent the pas- areas, which allow animals to access the water and sage of animals with semi-aquatic habits land environment (access to nests and specimen dis- persion) Continues Technical – Scientific Articles 161 Natureza & Conservação - vol. 6 - n.2 - October 2008 - pp. 157-170
  8. 8. Clóvis Souza Bujes - Laura Verrastro Continuation Table 2 Threats Recommendations or mitigating measures I Eutrofization because of intensive cattle raising or by or- I Rigorous control of water quality and the correct treat- ganic residue discharge. ment of residues. I Elimination of ciliary woods. I Environmental impact studies; regeneration of native riparian forests. I Animals such as dogs that prowl nesting areas, excava- I Keeping domestic animals locked, and not loose in ting the nests and eating eggs and hatchlings, a fact that marsh and/or nesting areas. is also observed in Pakistan (Akbar et al., 2006), where dogs captured adult turtles in shallow waters I Introduction of alien species in the Park’s area (e.g., the I Monitor and control populations of theses species: golden mussel Limnoperna fortunei – Manssur et al., evaluation of inter-specific competition; public aware- 2003). ness; species eradication campaigns. I Collection of specimens, specially hatchlings, for com- I Public awareness and guidance; law enforcement. merce or raise as pets and/or to keep in terrariums. I Specimens being run over on roads, especially during I Placement of speed bumps on the roads; building of breeding period (males migrating in search of females, subterranean bypasses in the areas where there is a adult females seeking nesting sites), movement of indi- greater incidence of run over of individuals. viduals between flooded areas and dispersion of young individuals. I Often breeding females were mistreated by humans who I To inform and make people aware on how to live along would beat or stone them. animals who do not harm human beings. I Use of specimens as food, which occurs especially with I Monitoring studies about the consumption of wild fau- the T. dorbigni e P. hilarii species. The collection of turtles na by the human population; monitor population on for human consumption in the Delta region is sporadic the medium and long terms; public awareness about and opportunistic. Some female P. hilarii are caught when the importance of the preservation of species. they are nesting, in this instance, both meat and eggs are consumed. I Commerce of hatchlings, especially the Orbigny’s slider. I Guidance and public awareness, enforcement of the law. dorbigni and Phrynops hilarii. habitats where they occur in higher numbers and biomass. Thus, several habitats in a flu- All turtles in Rio Grande do Sul are aquatic vial system can present similar species com- and their geographic distribution is generally position, but the abundance status of each limited to the presence of water in permanent species will differ. or seasonal environments. Fluvial environ- ments are dynamic and diversified ecosys- Moll & Moll (2004) verified that in 14 of 19 tems, made up of a variety of habitats, in- Neotropical turtle communities, the two most cluding main channels, tributaries, flooding abundant species make up over 75% of the plains, and lakes. According to Moll & Moll number of captured specimens. Among the (2004), each habitat might contain a certain four species, T. dorbigni was the most abun- community of chelonians. Even if the species dant (66% of the captures), followed by P. may appear anywhere in the fluvial ecosys- hilarii (21% of the captures), thus corrobora- tem, many of them specialize in one or more ting the authors’ assertion. Both T. dorbigni Technical – Scientific Articles 162 Natureza & Conservação - vol. 6 - n.2 - October 2008 - pp. 157-170
  9. 9. Chelonians from the Delta of Jacuí River, RS, Brazil: habitats use and conservation English and P. hilarii behave as eurioic species, with ment through greater discharges of organic day-time habits, easily observed during the material. According to Moll (1980), some hottest times of the day, and who regulate Testudines species can be physiologically op- thermally over surfaced materials (trunks, portunist, benefiting from special adaptations floating vegetation, rocks, debris, and so to aquatic environment that present low oxy- forth). Medem (1960), Monteiro & Diefenbach gen levels. Besides, organic residues consti- (1987), Molina (1989), and Souza (1999) made tute an extra source of food, since the larvae similar comments when they studied species of several species of insects that inhabit these such as the P. hilarii and P. geoffroanus. little oxygenized environments are the main prey of these animals, often leading the indi- Moll & Moll (2004) proposed that, apparen- viduals of these populations to be bigger tly, coexistence of two species from different (Moll, 1980; Souza & Abe, 2001). The environ- families in the same habitat is possible be- ments occupied by H. tectifera in the DJSP are cause there are species of fluvial turtles that similar to those described by Lema & Ferreira are specialist or optional. The Emydidae (1990), who state that the species occur in (considered optional fluvial turtles by Moll & lentic waters and in marshes, despite of being Legler, 1971; Moll & Moll, 1990) have become found by Ribas & Monteiro-Filho (2002) in dominant in several rivers in regions ranging lotic waters (creeks and brooks). from Northern Mexico to Northern South America, with the exception of small areas in In the DJSP, the Chelidae Acanthochelys spixii Central America, there is no specialist fluvial was recorded in marsh environments and turtle competing for this habitat. One cannot ephemeral aquatic environments, such as irri- classify T. dorbigni and P. hilarii in this cate- gation channel, rice paddies, water holes, and gory of specialist or optional fluvial turtles draining ditches on rice plantations. D’Amato because, despite the apparent domination by & Morato (1991) reported that this species is T. dorbigni, both were species found in all very common in small creeks and marshes sampling points (TABLE 1) and who occu- near residential and industrial areas. Ribas & pied the most diversified habitats, both per- Monteiro-Filho (2002) reported that, in the manent and ephemeral. state of Paraná, the A. spixii was found in flooded areas which present abundance of In consonance with data obtained by Richard grass and areas of temporary flooding during (1999), P. hilarii was found occupying envi- the raining season. ronments permanently flooded and, when present in those which presented a temporary The species with the lowest capture frequen- character, they always were related to perma- cy was H. tectifera, however, it occurred in the nent habitats located nearby. three sampled areas, while A. spixii presented a slight higher capture frequency, but none Hydromedusa tectifera (Chelidae) has presen- was captured in one of the areas. Stone et al. ted a great behavioral plasticity and resist- (2005), when studying a turtle assembly in ance to different environmental conditions: the United States, argued that part of the dis- specimens were found in sewers in the urban tribution or low capture frequency of area (Pintada Island), in environments that re- Kinosternon flavescens might be due to sam- ceive pesticide discharges (Fazenda Kramm), pling error, since that species spends a great and in apparently more preserved sites (inter- part of the time summering or hibernating on nal marsh at the Flores Island). Ribas & land. H. tectifera uses to bury in the mud as Monteiro Filho (2002) found H. tectifera, as the places become dry, a behavior that was al- well as P. geoffroanus and P. williamsi Rhodin so observed during the winter, and reappear- & Mittermeier 1983 in environments with ing in springtime (Lema & Ferreira, 1990). high degree of anthropic influence, where ri- This habit was also verified by Bujes (2006, ver pollution modifies the aquatic environ- personal correspondence) for the A. spixii Technical – Scientific Articles 163 Natureza & Conservação - vol. 6 - n.2 - October 2008 - pp. 157-170
  10. 10. Clóvis Souza Bujes - Laura Verrastro species and might have contributed for the preventing animals to access adjacent land low frequency estimates of occurrence and for dislocation and/or nesting. The increase abundance relative to both species. in urbanization has shown to be responsible for drastic changes in many animal popula- The species listed in this study also occupied tions, e.g. large carnivores (Reilly et al., 2003), water holes, a very peculiar environment re- butterflies (Collinge et al., 2003), salamanders sulting from anthropic action. At the DJSP, the (Willson & Dorcas, 2003), and fish (Paul & water holes are true craters, resulting from il- Meyer, 2001), as well as vegetation communi- legal extraction of sand in a marsh area next ties, both on land environments (Francisco- to the Fazenda Kramm. They are ephemeral Ortega et al., 2000) and aquatic environments environments, containing water only during (Fore & Grafe, 2002). raining periods. These temporary habitats seem to make available the biggest supply of De la Ossa-Velásquez & Fajardo (1998) con- food resources that propitiate favorable con- sidered the destruction and alteration of na- ditions for growth and breeding, offering tural environments the gravest threats for the shelter and nesting areas to the species survival of Phrynops dahli, an endemic species (Kennett & Georges, 1990). in Colombia whose habitat almost complete- ly disappeared as result of the expansion of Moll & Moll (2004) reported that turtle com- the agricultural frontier and urban develop- munities tend to be relatively poor in number ment. Deforestation of riparian vegetation of species and usually one or two species oc- and the resulting alteration on the banks of cur together in the same habitat, which might rivers might, according to Hildebrand & also be attributed to the chelonian communi- Muñoz (1992), have provoked the destruction ty in the DJSP. of all reproductive efforts by chelonian species in Colombia. With the exception of Acanthochelys spixii, which is categorized as low risk/non-threa- Gibbons et al. (2000) considered the destruc- tened (LR/NT) in the IUCN Red List (2006), tion/fragmentation of habitats as the gravest chelonians in the DJSP are not listed in the na- threat to biodiversity, followed by the intro- tional lists of endangered species. However, duction of alien species, environmental pollu- impact caused by deforestation and pollution tion, diseases and parasitism, unsustainable in the Delta do Jacuí region might represent usage, and changes in global climate. serious risks to the survival of those species. According to Tabarelli et al. (2004), deforesta- The threats mentioned and the situations ob- tion has direct and indirect effects on the re- served at the DJSP (TABLE 2) do not affect, duction of habitats of plant and animal for obvious reasons, just the chelonians, but species. As an example of direct effect, the au- also the other species of fauna and flora. The thors mention the elimination of vertebrates frailty of turtle populations is linked to the dispersers of seeds, thus compromising ger- low recruiting rates, low population density, mination. Regarding the indirect ones, they and habitat fragmentation. Undoubtedly, mention the production of large quantities of habitat changes was the gravest threat that organic detritus that, combined to trash and was verified in the DJSP, which results in the dead biomass, occurring due to fragmenta- reduction or absolute loss of environments tion, leave certain regions even more suscep- necessary to essential vital functions of seve- tible to fires. Burke et al. (1994) suggested that ral organisms, including food (Vickery et al., turtles might be especially vulnerable to po- 2001), breeding (Heckert et al., 2003) and shel- pulation decline because of their breeding ter (Ball, 2002). Removal of ciliary vegetation strategies, which are incompatible with the was observed at the DJSP for building of exploitation and significant habitat loss. houses and the building of dikes on the banks, aiming at water contention and thus Education is an important tool for the deve- Technical – Scientific Articles 164 Natureza & Conservação - vol. 6 - n.2 - October 2008 - pp. 157-170
  11. 11. Chelonians from the Delta of Jacuí River, RS, Brazil: habitats use and conservation English lopment of a posture that leads to conservation AKNOWLEDGEMENTS: projects, and it also is a key-element in their success, as people involved in, or affected by, We thank the Fundação O Boticário de the programs are informed on the need for that Proteção à Natureza (FBPN, Projeto action and the benefits of the program for their Chelonia–RS 0594-20032) for financial sup- present and their future. For Congdon et al. port; the Instituto Gaúcho de Estudos (1993), successful turtle management and con- Ambientais (INGA), the Secretaria Estadual servation programs would be those that recog- do Meio Ambiente (SEMA), and the Zoology nize that protection is necessary in all stages of Departament at the Universidade Federal do the organisms’ life history. Rio Grande do Sul (UFRGS) for logistical sup- port; and to the staff at the Delta do Jacuí CONCLUSION State Park, especially Loiva and Clemente. And to our colleagues Flávio de Barros The chelonian community in the DJSP is Molina, PhD, and Márcio Borges Martins, made up of four species that occupy different PhD, for their valuable contribution in the types of habitat, including permanent and proofreading of the manuscript. ephemeral aquatic environments. Threats to the survival of these species are many and are intimately related to the human presence in REFERENCES the Park area. In face of the matters presented in this study, it is evident that there is a pres- Accordi, I.A. 2002. Asas do delta: aves entre a sing need for public awareness about the im- terra e água. In: Fundação Zoobotânica do portance of chelonians and the fact that living Rio Grande do Sul (ed.). Natureza em revista: along them does not harm human beings. Delta do Jacuí. Pp. 54-59. Porto Alegre: Nevertheless, control must be intensified, as Fundação Zoobotânica do Rio Grande do Sul. must the enforcement of environmental legis- lation, as well as the implementation of stu- Acuña-Mesen, R. A.; Castaing, A.; Flores, F. dies for in loco protection of animals and the 1983. Aspectos ecológicos de la distribución environments they occupy. de las tortugas terrestres y semiacuáticas en el Valle Central de Costa Rica. Revista de Biologia Tropical, 31 (2): 181-192. Akbar, M.; Hassan, M. M.; Nisa, Z. 2006. Distribution of freshwater turtles in Punjab, Pakistan. Caspian Journal of Environmental Sciences, 4 (2): 142-146. Ball, L. C. 2002. A strategy for describing and monitoring bat habitat. Journal Wildlife Management, 66: 1148-1153. Branco-Filho, C. C.; Basso, L. A. 2005. Ocupação irregular e degradação ambiental no Parque Estadual Delta do Jacuí-RS. Geografia, 30(2): 285-302. Burke, V. J.; Gibbons, J. W.; Greene, J. L. 1994. Prolonged nesting forays by common mud turtles (Kinosternon subrubrum). American Midland Naturalist, 131 (1): 190-195. Technical – Scientific Articles 165 Natureza & Conservação - vol. 6 - n.2 - October 2008 - pp. 157-170
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