Spatial Niche Expansion at Multiple Habitat Scales of a Tropical Freshwater Turtle in the Absence of a Potential Competitor

Abstract

Resource partitioning, the division of limited resources by species to help avoid competition, has been observed in freshwater turtle assemblages in several natural systems but has rarely been studied in tropical African ecosystems. Here, we investigate habitat preferences of two congeneric species in the family Pelomedusidae, Pelusios castaneus and P. cupulatta, in riverine/wetland habitats in the southern Ivory Coast (West Africa). Pelusios castaneus is a widespread species across West-central African savannahs and open forests, whereas P. cupulatta is endemic to the Upper Guinean forest region in West Africa. The two species have a similar diet composition (mainly carnivorous) but diverge considerably in body size, P. cupulatta being much larger. We use hand-fishing-nets and fishing funnel traps to record turtles in 18 distinct sites and analyze habitat preferences by species at two spatial scales. At a macro-habitat scale, P. castaneus is captured mainly in marshlands, whereas P. cupulatta is found in both rivers and wetlands. The two species differ significantly in their use of: (i) banks (P. castaneus being found primarily in spots with grassy banks, whereas P. cupulatta is found in spots with forested banks), and (ii) aquatic vegetation (P. cupulatta prefers spots with more abundant aquatic vegetation than P. castaneus), but both species select sites with no or moderate current. Additionally, in sites where P. cupulatta is not found, P. castaneus expands its spatial niche at multiple habitat scales, notably invading waterbodies with forested banks. Our results suggest that these two Pelomedusid turtle species potentially compete in the freshwater habitats in the southern Ivory Coast.

Influence of landscape condition on relative abundance and body condition of two generalist freshwater turtle species

“…However, the two species differed in individual-level responses, with reduced ecological integrity appearing to negatively impact painted turtles but not red-eared sliders. This indicates that painted turtles may benefit from anthropogenic land uses through other factors than improved habitat quality, such as reduced predation or competition pressure, which has been documented for other freshwater turtle species (Petrozzi et al, 2021;Ryan et al, 2008;Spencer & Thompson, 2005).…”

Distribution extension and first verified records for Narrow-bridged Musk Turtle, Claudius angustatus Cope, 1865 (Testudines, Kinosternidae) in the Selva Lacandona, Mexico

“…Additionally, this species has been reported in floodplains and semi-permanent water bodies surrounded by cattle pastures (Reynoso et al 2016), in pastures (Aguilar-López et al 2020), or in sugarcane fields (Vásquez-Cruz and Reynoso-Martínez 2020). This is not surprising, as some aquatic turtles can inhabit several aquatic environments (e.g., rivulets or temporary ponds) located inside anthropic matrices, such as tree plantations and cattle pastures (Legler and Vogt 2013;Petrozzi et al 2021). However, the anthropic matrix can also represent a threat to this species, suggested by the reports of several death specimens found in burned plantations (Cedeño-Vázquez and Beutelspacher-García 2016;Reynoso et al 2016).…”

Community Characteristics of Sympatric Freshwater Turtles from Savannah Waterbodies in Ghana

“…Also the West African endemic Pelusios cupulatta was not observed during our surveys, but it is possible that this was due to unsatisfying eld effort at the single locality where this species may be present (Tano River). This species was fairly common in similar habitats in Cote d'Ivoire, where it occurs sympatrically with P. castaneus (Petrozzi et al, 2021).…”

“…Consequently, turtle species may show a nity for certain aquatic environmental conditions such as water level, water quality, ow characteristics, substrate type and vegetation, but also choose bank features for basking and nesting (Ficetola et al 2004;Vignoli et al 2015;Luiselli et al 2020). A turtle community is also in uenced by the characteristics of terrestrial habitats surrounding the water bodies (Marchand and Litvaitis 2004;Luiselli et al 2020), often resulting from interspeci c competition as highlighted in both temperate and tropical environments (e.g., Joly 2003, 2004;Luiselli 2008;Petrozzi et al 2021).…”

“…Previous freshwater turtle research in West Africa focused on taxonomy and distribution of species (e.g., Hoogmoed 1980;Bour and Maran 2003;Bombi et al 2011;Segniagbeto et al 2014 and references therein). More recently, much effort has been placed on the analysis of aspects of turtle community ecology that relate to habitat characteristics, including the effects of habitat pollution and degradation (e.g., Luiselli et al 2000Luiselli et al , 2004 and on the niche partitioning patterns and interspeci c competition in rainforests areas (e.g., Luiselli et al 2006aLuiselli et al , 2006bPetrozzi et al 2021). Conversely, only one turtle community ecology study is available from the waterbodies of the Dahomey Gap (Luiselli et al 2020).…”