Trionyx triunguis (Forskål 1775) – African Softshell Turtle, Nile Softshell Turtle
Kitapta bölümler > Diğer · 2025
Yazarlar: Pearson McGovern, Ertan Taskavak, Peter A. Meylan, Gift Simon Demaya, Gabriel H. Segniagbeto, Mathias Behangana, Fabio Petrozzi, Edem A. Eniang, Yaron Tikochinski, Mehmet K. Atatür
Chelonian Research Monographs, Diğer, Uluslararası, 2025, ,
DOI: 10.3854/crm.5.129.triunguis.v1.2025
Özet
The African Softshell Turtle, Trionyx triunguis (family Trionychidae), is a large (up to >100 cm straight-line carapace length), fresh- and salt-water tolerant species predominantly found in moderately deep streams, rivers, estuarine systems, and lakes. It is the most widely distributed turtle in Africa, ranging from the mouth of the Nile River system south to Lakes Turkana (Rudolf) and Albert in eastern Africa, and from the Cunene River in northern Namibia to Senegal in western Africa. Additionally, it is found in the western Mediterranean region from the Turkish coastal zone to Israel. African populations are thought to have experienced significant declines in recent decades and Mediterranean populations have been considered Critically Endangered by the IUCN. While there is little published about the habitat preferences and ecology of the species, it appears to prefer medium to large sized rivers and permanent waterbodies with muddy, organic substrates, abundant emergent vegetation, and forested banks. Most accounts of nesting come from Mediterranean populations, where nesting takes place between May and July–August, with hatchling emergence from July to September after an incubation of 54–75 days. Clutch sizes seem to be highly variable between studies, seasons, and countries, with clutch size averages ranging from 23.0–44.7 eggs; up to 66 eggs have been recorded. The near spherical eggs are roughly 30–35 mm in diameter and weigh ~20 g. Most nests are between 20–40 cm deep and laid within 15 m of the water’s edge. As seen in all other trionychids, T. triunguis does not exhibit temperature-dependent sex determination. Optimal nest temperatures are between 24–33ºC, with around 30ºC producing maximum hatching success. Nest predation seems to be high where nesting has been recorded, with monitor lizards, domestic dogs, weasels, foxes, and jackals reported as the predominant predators. Hatchlings typically measure 40–51 mm SCL and weigh 10–15 g. Double and triple clutching have been noted in the species (though the frequency of multiple clutches remains unknown). Other than high nest predation rates, threats include entanglement in fishing gear, subsistence hunting, targeted hunting for the bushmeat trade, wanton killing, pollution, sand mining, and destruction of nesting beaches and sandbanks. The species is estimated to be Vulnerable and decreasing throughout its range and increased conservation efforts are warranted.