Fig 1 - uploaded by Roger Bour
Content may be subject to copyright.
Source publication
The turtles are an evolutionary ancient group of tetrapod vertebrates, and their present-day distribution and diversity reflects
the long and complex history of the taxon. Today, about 250 of the total of 320 species recognized are freshwater turtles;
most of these inhabit tropical and subtropical zones.Diversity hotspots occur in SoutheastNorthAme...
Context in source publication
Context 1
... more or less retractable inside the shell: ''hidden neck''), are still present today, although they have different and unequal areas of occurrence and species richness. Cryptodira includes freshwater turtles in addition to marine turtles and terrestrial tortoises, while all Pleurodira species are more or less completely fresh- water dependant (Fig. ...
Similar publications
New investigations of freshwater habitats in mountainous regions and caves revealed six new species of the Rissooidea in Bulgaria. The new species are described here and photos of the holotypes are provided. In addition we added photos of the type localities. An identification key of the genera of the Rissooidea of Bulgaria gives an overview of the...
In 1966, Matthew Hohn and Joan Hellerman described 44 diatom species from one freshwater and several coastal habitats along the Atlantic coast of the USA. The goal of our study was to examine the type materials of these species and to evaluate their taxonomic status. Type specimens of 32 taxa were located and documented with light microscopy, and o...
The genus Caloneis Cleve is widely spread in freshwater and brackish water habitats. The recent observations of oligotrophic lakes show great diversity of the genus with the presence of many unidentified taxa. Among the lakes, the ancient lakes have a specific place because of their high level of diversity and endemism. Lakes Ohrid and Prespa, as o...
Citations
... Asian freshwater turtles are currently suffering massive regional declines, mostly driven by unsustainable harvesting for the international food and pet trade (Cheung & Dudgeon 2006, Gong et al. 2009). Whilst China constitutes the largest trade market, Southeast Asia is the primary source of harvested turtles, which due to the region's high turtle diversity and local endemism is a major cause for concern (Bour 2008, Rhodin et al. 2017. Overharvesting is exacerbated by habitat disturbance/loss, urbanisation and hydro-electric dam development in the region (Van Dijk 2000). ...
... Our aquatic observations of N. platynota (N = 156) and D. subplana (N = 39), suggest a predominantly aquatic lifestyle in concordance with the majority of the literature (Bour 2008, Ernst & Barbour 1989, Lim & Das 1999, Manthey & Grossmann 1997, Nutaphand 1979, Rog ner 1995. However, aquatic observations of H. spinosa (N = 10) contradict many previous records. ...
Asian freshwater turtles are severely threatened by overharvesting for local and international trade. Whilst some research exists on their occurrence in market places, basic studies on their natural history are scarce. Effective conservation action requires an understanding of both the threats to a species and its ecology. Our research aims to elucidate some basic aspects of the natural history of three freshwater turtle species: Notochelys platynota, Heosemys spinosa and Dogania subplana in Sabah, Malaysian Borneo. We collected opportunistic turtle data within two logging concessions from 2017 to 2019, and conducted dedicated turtle sampling via Visual Encounter Surveys (VES) along rivers in 2019. These data were used to determine population characteristics, habitat associations/separation, movements, recapture rates, breeding behaviour, and parasitism. We obtained 157, 40 and 13 records of N. platynota, D. subplana and H. spinosa, respectively. Roughly equal adult/juvenile ratios were detected in two species, whereas adults predominated (2.6:1) in N. platynota. Both N. platynota and H. spinosa exhibited similar sex ratios, with significant sexual dimorphism (males larger than females) in N. platynota. Notochelys platynota and D. subplana were significantly associated with wider streams compared to H. spinosa, whilst D. subplana were significantly associated with higher relative siltation than N. platynota. Recapture rates of N. platynota were low (N = 12), with recaptured N. platynota movements ranging from 10-489 meters. High rates of parasitism by freshwater leeches (Placobdelloides siamensis) were identified in N. platynota (41% of VES detections, N = 50), whilst 30% of H. spinosa were infested with ticks (N = 3). The effects of high parasitism on N. platynota require further study, however we observed a large breeding population of N. platynota in the logging reserves examined. Habitat separation between these three species at fine spatial scales, via stream width and siltation, likely permits their co-occurrence along the same stream networks. We recommend the protection of heterogeneous stream networks to improve effective conservation measures for these species.
... Chelonians (order Testudines) are considered one of the most ancient recent groups of tetrapods, with the first known records from the Triassic being around 230 million years old (Bour 2008). Currently, 356 species are recognized, classified in 14 families. ...
... Approximately 356 extant species of freshwater and terrestrial chelonians are distributed around the world, except Polar regions (Bour 2008). Some regions are considered hot spots for this group. ...
... Research on spatial ecology usually requires long periods of monitoring, which demand extensive fieldwork and monetary resources. The Western Palae arctic experienced a limited diversification of studies on non-marine chelonians when compared to other regions (Bour 2008, Buhlmann et al. 2009). However, the few studies conducted in the Western Palaearctic can be considered relevant in view of the small radiation of this group in this region. ...
Use of space refers to the quantity and quality of habitat exploitation by animals in a certain locality. While quantity is the area of space used by the animal for its activities, quality refers to the locale and manner in which the animal selects its home range. Both parameters are of crucial importance in driving species distribution and abundance. Testudines are distributed across diverse regions, including areas under severe anthropogenic pressure, and many species are threatened, mainly due to habitat loss and overexploitation. We reviewed scientific literature published between 1995 and 2016 to assess taxonomic and geographic patterns in home ranges of freshwater and terrestrial chelonians based on biological and ecological characteristics and conservation status. We examined the trait “home range size”, as well as its relationships with intrinsic and extrinsic factors (sex, diet, carapace size, habitat and study zone) and species-specific conservation status. Many of the reviewed studies focus on the Nearctic region, and Emydidae is the most commonly studied family. We found great variation in the home range sizes of species within the same family. Diet was identified as the main driver of home range size. Sex, carapace size, habitat and study zone were not significant as predictors of home range size. Conservation status does not seem to represent a factor driving the assessed studies since the number of investigations concerning threatened and non-threatened species was similar. Home range sizes of threatened species were significantly lower than those of non-threatened species. We recommend priority be applied on information gathering and defining conservation strategies for species in undersampled areas threatened by habitat loss.
... Las 257 especies de tortugas acuáticas están distribuidas alrededor del mundo, principalmente en ambientes tropicales y subtropicales, y en menor grado en regiones templadas (Anexo, Figura 2) 19,20 . Las tortugas acuáticas pueden caracterizarse por la diversidad: ocupan ambientes que abarcan desde grandes ríos y lagos hasta esteros, pantanos, humedales, charcas estacionales y aguas salobres, entre otros 19,21 . ...
... Las 257 especies de tortugas acuáticas están distribuidas alrededor del mundo, principalmente en ambientes tropicales y subtropicales, y en menor grado en regiones templadas (Anexo, Figura 2) 19,20 . Las tortugas acuáticas pueden caracterizarse por la diversidad: ocupan ambientes que abarcan desde grandes ríos y lagos hasta esteros, pantanos, humedales, charcas estacionales y aguas salobres, entre otros 19,21 . A nivel especie o género, optan por hábitats particulares y la mayoría de los taxones son endémicos; es decir, cuentan con una distribución geográfica única y limitada 19,21,22 . ...
... Las tortugas acuáticas pueden caracterizarse por la diversidad: ocupan ambientes que abarcan desde grandes ríos y lagos hasta esteros, pantanos, humedales, charcas estacionales y aguas salobres, entre otros 19,21 . A nivel especie o género, optan por hábitats particulares y la mayoría de los taxones son endémicos; es decir, cuentan con una distribución geográfica única y limitada 19,21,22 . ...
Contar la historia de las tortugas marinas y acuáticas es contar la historia de la Tierra en los últimos 200 millones de años. Los procesos geológicos —como la tectónica de placas y los cambios climáticos— han ampliado y restringido sus distribuciones, y separado poblaciones llevando a procesos de especiación. Los parámetros químicos como la temperatura y la salinidad delimitan su distribución en función de sus límites fisiológicos —que abarcan una gama de adaptaciones a los cambios generados a lo largo de millones de años — y de la disponibilidad de recursos alimentarios. En el mar, los procesos abióticos como los cambios en la circulación oceánica, las surgencias y los frentes oceánicos han contribuido a los procesos evolutivos como mecanismos de dispersión, barreras al flujo genético, hábitats y corredores migratorios.
... This can be attributed to their basking behaviour which requires exposure to solar radiation. Yet, a closed canopy should not be interpreted as a cause of declining terrapin populations; rather, sparse canopy is an environmental correlate of larger aquatic ecosystems such as large-sized sluggish rivers, swamps, and lakes that are conducive to terrapins (Bour, 2008;Deraniyagala, 1939;Sethy, Samantasinghar, & Pramanik, 2015). ...
Terrapins are integral to many freshwater ecosystems, yet are imperilled at a global scale. In Sri Lanka, terrapins are understudied; thus, much of their natural history and distribution status remain unknown. Such paucity of studies impedes conservation.
In this study, 79 freshwater habitats located outside the protected area network of south‐western Sri Lanka were surveyed to document current population densities and habitat use of two terrapin species: Indian black terrapin ( Melanochelys trijuga thermalis ) and flap‐shelled terrapin ( Lissemys ceylonensis ). Local inhabitants were interviewed to assess human threats towards terrapins.
Both species were recorded in low densities: 1–2 individuals ha ⁻¹ . Indian black terrapin was found in half of the surveyed sites while flap‐shelled terrapin occurred in one‐third of the surveyed sites. Highly urbanized river basins had the lowest densities for both species while rural basins supported higher numbers. Basking was the predominant behaviour of both species and large woody debris and boulders were preferred as basking substrates, together with sparse‐canopy aquatic habitats with intact marshlands.
Overharvesting for meat was a major threat for terrapins. Most local inhabitants were unaware of legislation on terrapin conservation and the ecological importance of terrapins. Human threats such as pollution, modification of aquatic and wetland habitats, and loss of riparian forests were frequently observed in surveyed sites. Terrapin populations outside the protected area are at risk as evidenced by lower population densities and a multitude of human threats.
A landscape‐scale ecosystem‐based conservation approach is recommended for Sri Lanka's terrapins with incorporation of lands with different management regimes (privately owned, municipality managed) into the protected area network. Current environmental legislation should be revised to support buffer zone delineation for aquatic habitats, wetland restoration, and landscape‐scale connectivity.
... Globally turtles are known to be very sensitive to modifications of their environment. They are often among the first vertebrates to disappear from impacted or altered habitats [5] and, as a result, they represent one of the most endangered groups of animals [6,7]. Of the 327 recognised species of extant chelonians (turtles and tortoises) that are distributed throughout the most hospitable ecoregions [4], 63% are considered threatened [6]. ...
Background
Polystomatid flatworms in chelonians are divided into three genera, i.e. Polystomoides Ward, 1917, Polystomoidella Price, 1939 and Neopolystoma Price, 1939, according to the number of haptoral hooks. Among the about 55 polystome species that are known to date from the 327 modern living chelonians, only four species of Polystomoides are currently recognised within the 45 South American freshwater turtles. Methods
During 2012, several sites in the vicinity of the cities Cayenne and Kaw in French Guiana were investigated for freshwater turtles. Turtles were collected at six sites and the presence of polystomatid flatworms was assessed from the presence of polystome eggs released by infected specimens. ResultsAmong the three turtle species that were collected, no polystomes were found in the gibba turtle Mesoclemmys gibba (Schweigger, 1812). The spot-legged turtle Rhinoclemmys punctularia (Daudin, 1801) was infected with two species of Neopolystoma Price, 1939, one in the conjunctival sacs and the other in the urinary bladder, while the scorpion mud turtle Kinosternon scorpioides (Linnaeus, 1766) was found to be infected with a single Neopolystoma species in the conjunctival sacs. These parasites could be distinguished from known species of Neopolystoma by a combination of morphological characteristics including body size, number and length of genital spines, shape and size of the testis. They were also differentiated at the molecular level using the cox1 gene marker. Based on morphological and genetic evidences, three new species are described herein, namely Neopolystoma cayensis n. sp. and Neopolystoma guianensis n. sp. from the bladder and the conjunctival sacs of R. punctularia, respectively, and Neopolystoma scorpioides n. sp. from the conjunctival sacs of K. scorpioides. However the monophyly of Polystomoides and Neopolystoma is still questioned regarding their phylogeny based on a dataset comprising four concatenated genes, namely, 18S, 28S and 12S rRNA genes and cox1. Conclusions
In addition to these being the first chelonian polystomes to be reported and described from French Guiana, they represent the first polystomes from the hosts K. scorpioides and R. punctularia and the first representatives of Neopolystoma from South America. Chelonian polystomes now require an in-depth morphological study to reconcile the taxonomy of the genera with species evolution.
... We will treat here under this name all extant Sauropsida groups, except birds, which will be treated in another section. Bour (2008) cited only 8 species and 6 genera of aquatic Chelonii (of the 257 species included in 79 genera found worldwide) that inhabit the Palearctic region. In the Med, 7 species are present (Rhodin et al., 2010;IUCN, 2011;Uetz et al., 2011): 2 species of the Emys genus, one of them recently described as a cryptic species (Fritz et al., 2005) and endemic to the Med but of controversial taxonomical validity because different molecular approaches (mitochondrial vs nuclear DNA studies) show contradictory results (Spinks & Shaffer, 2009); 1 species of the Rafetus; 1 species of the Trionyx genus; and 3 species of the Mauremys genus. ...
We review the diversity of freshwater organisms in the Mediterranean Basin (hereafter Med), particularly from streams and rivers. We present available information on the richness, endemicity, and distribution of each freshwater organism group within the Med, and make a comparison with Palearctic diversity. Approximately 35% of known Palearctic freshwater species and more than 6% of the World’s freshwater species are present in the Med. A high degree of endemicity is found in the Med freshwater biota. These data, together with the degree to which many freshwater species are threatened, support the inclusion of the Med among World biodiversity hotspots. Nevertheless, knowledge of Med biodiversity is still incomplete, particularly for some taxa. Regarding to the spatial distribution of species within the Med, the richest area is the North, although patterns differ among groups. A comparison of the ecological and biological traits of endemic and non-endemic species of three riverine groups (Ephemeroptera, Plecoptera, and Trichoptera) revealed that endemic species have several strategies and mechanisms to face typical mediterranean-climate conditions, such as drought, when compared to non-endemic species. We briefly analyse the conservation status of the region’s biodiversity. Finally, we present some future challenges regarding the knowledge and protection of Med freshwater biodiversity.
... Freshwater turtles are an evolutionarily ancient and ecologically important group with long and complex histories in a variety of aquatic ecosystems (Bour, 2008). Adult aquatic turtles often dominate pond ecosystems in the southeastern United States as top predators (Aresco and James, 2005). ...
The effect of red-eared sliders (Trachemys scripta elegans) on aquatic ecosystem processes and macroinvertebrate community was investigated in artificial ponds that were stocked with turtles or kept free of them. Compared to ponds without turtles, ponds with turtles displayed significantly higher values of pH, conductivity, sediment accumulation, and leaf litter decomposition rates, as well as a higher abundance of invertebrates, specifically that of the Hemiptera and Ephemeroptera. The biomass of periphyton was not affected by the presence of turtles. These results suggest that the presence of T. s. elegans affects environmental conditions in ponds, and thus potentially ecosystem processes. Reduced abundance or loss of turtles in aquatic systems could therefore result in significant consequences on ecosystem functioning.
... ). Bour (2008) assessed the large-scale distribution of chelonian species on the scale of biogeographic realms. Buhlmann et al. (2009) extended this approach and assessed current global tortoise and freshwater turtle distribution based on hydrologic unit compartments (HUC) and based on that identified areas of high conservation priority. ...
Anthropogenic global climate change has already led to alterations in biodiversity patterns by directly and indirectly affecting species distributions. It has been suggested that poikilothermic animals, including reptiles, will be particularly affected by global change and large-scale reptile declines have already been observed. Currently, half of the world's freshwater turtles and tortoises are considered threatened with extinction, and climate change may exacerbate these declines. In this study, we assess how global chelonian species richness will change in the near future. We use species distribution models developed under current climate conditions for 78% of all extant species and project them onto different Intergovernmental Panel on Climate Change (IPCC) scenarios for 2080. We detect a strong dependence of temperature shaping most species ranges, which coincide with their general temperature-related physiological traits (i.e., temperature-dependent sex determination). Furthermore, the extent and distribution of the current bioclimatic niches of most chelonians may change remarkably in the near future, likely leading to a substantial decrease of local species abundance and ultimately a reduction in species richness. Future climatic changes may cause the ranges of 86% of the species to contract, and of these ranges, nearly 12% are predicted to be situated completely outside their currently realized niches. Hence, the interplay of increasing habitat fragmentation and loss due to climatic stress may result in a serious threat for several chelonian species.
... El bosque de ribera es el hábitat con la más alta riqueza y diversidad de especies en la zona de estudio, algunas especies de reptiles se asocian casi de forma exclusiva a hábitats con permanente presencia de agua o a la vegetación en el borde o flotante, por ejemplo las tortugas (Kinosternon scorpioides, Mesoclemmys dahli, Rhinoclemys melanosterna y Trachemys callirostris), la babilla (Caiman crocodilus), dos saurios (Tupinambis teguixin y Basiliscus basiliscus) y una especie de serpiente (Helicops danieli). Estas especies se relacionan más a este tipo de ambientes en cuanto a forrajeo y desarrollo de sus historias naturales, de acuerdo con el ciclo dinámico que liga a muchas especies a los cambios espaciales de las ciénagas u otro tipo de cuerpos de agua (Paton 2005, Bauer & Jackman 2008, Bour 2008, Martin 2008, Pauwells et al. 2008 ). El recurso léntico favorece el establecimiento de poblaciones permanentes que ocupan estos espacios; la mayoría actualmente en riesgo (Castaño-Mora 2002) y seguramente caracterizados por la pérdida de este tipo de hábitat. ...
Diversity is a property of community that can described, characterized, and understood according to the functioning of ecosystems. To study the richness and local abundance and species replacement between habitats around the Zapatosa's wetland complex (El Cesar Department), I carried out four field trips between November of 2006 and October of 2007. A total of 640 sampling hours/man analyzed five habitat types chasmophyte forest, dry forest, riparian forest, palm-grove and tree-lined savanna; with the exception of the palm-grove sampled at its 75%, the others were sampled up to their 80%. I found 847 reptiles that were distributed in 48 species. The group with the highest number of species was Colubridae with 14, followed by Gekkonidae with five. Five endemic species and eight with some conservation threat grade at a national level are reported. The riparian forest was the richest and most abundant habitat with 34 species and 196 individuals. For each habitat, Colubridae had the highest number of species, followed by the families Polychrotidae, Gekkonidae and Teiidae, in that order. The reptile species composition was not different between the tree-lined savanna and the chasmophyte forest, but differed among the tree-lined savanna and the riparian forest, palm-grove and dry forest habitats. The most important differences in the species composition among almost all the habitats were influenced by the species Anolis tropidogaster and Gonatodes albogularis, and the higher occurrence of Stenocercus erythrogaster in the chasmophyte forest. The species replacement had an average value of 50%; the biggest amounts of shared species were the lizards, while the snake Leptodeira septentrionalis was the only one present in all habitat types. The forest grows-among-rocks showed the biggest complementarity and number of unique species compared to the other habitats. The wetland complex provides two thirds of the reptile's species reported until now for the Caribbean region, and more than 80% of those reported for the El Cesar department. This wetland complex seems to behave as a center for low land species concentration as it hosts a high proportion of species from those places.
... crayfishes (Crandall & Buhay, 2008), molluscs (Bogan, 2008;Strong et al., 2008), fishes (Leveque et al., 2008 and fishbase.org), birds (Dehorter & Guillemain, 2008;Clements et al., 2009), reptiles (Bauer & Jackman, 2008;Bour, 2008;Martin, 2008;Pauwels, Wallach & David, 2008) and mammals (Veron, Patterson & Reeves, 2008). We included genera or families known to be freshwater-dominated (>50% species freshwater-associated). ...
1. Freshwater ecosystems, including ponds, lakes, streams and rivers, represent an interaction nexus between environmental change and a wide variety of infectious diseases, including human malaria, salmonid whirling disease, amphibian chytridiomycosis, crayfish plague and many others. However, few studies have explicitly examined patterns of disease in fresh waters and how they are changing over time.
2. Freshwater environments can function as transmission foci for pathogens because of (i) the importance of fresh water for organism survival, (ii) the aquatic life histories of many vectors and intermediate hosts, (iii) the concentrated aggregations of species – both freshwater and terrestrial – in and around freshwater habitats and (iv) the highly altered condition of freshwater ecosystems, which can affect species interactions and disease pathology.
3. To determine whether water-related diseases in wildlife are increasing, we used generalised additive models to quantitatively assess trends in the scientific literature (1970–2009) for major freshwater groups, including amphibians, molluscs, crayfishes, fishes, mammals, reptiles and birds. We further examined what types of pathogens were primarily responsible for observed patterns and whether recurrent groups or transmission modes could be identified.
4. After correcting for research effort and temporal autocorrelation, we find that reports of disease varied over time and across freshwater taxa, with significant increases in amphibians, fishes and crayfishes, a significant decrease in molluscs, and no significant change in freshwater reptiles, birds or mammals. The types and diversity of pathogens varied considerably among groups. Reports of infection in amphibians were dominated by helminths and a chytridiomycete, in crayfishes by viruses and fungi, in molluscs by digenetic trematodes, in birds, fishes and mammals by viruses, protists and helminths and in reptiles by helminths and bacteria.
5. These results provide some of the first quantitative evidence indicative of a long-term increase in disease-related research for freshwater taxa. Managing freshwater ecosystems to reduce or minimise human and wildlife disease risk – arguably one of the most significant ecosystem services – will require enhanced incorporation of ecological approaches alongside medical and veterinary tools.
