Fishes of Lely and Nassau Mountains, Suriname

Abstract

The fish fauna of Lely Mountains and Nassau Mountains was sampled at 4 and 3 sites, respectively, during a Rapid Assessment Program expedition in November 2005. A total of 36 species were identified. Of these, 26 were collected in a lowland stream in the foot hills of Nassau Mountains (altitude 106 m above mean sea level). The fish fauna of 4 high-altitude (plateau) streams in Lely Mountains had 8 species. In high-altitude reaches of one stream in Nassau Mountains (Paramaka Creek) we collected 6 fish species, including the endemic cat-fish Harttiella crassicauda. A second survey of plateau streams in Nassau Mountains in March/ April 2006 increased the number of species to 41; 11 species, including 6 species that are potentially new species to science, were collected from high-altitude streams. The low number of fish species in the high-altitude streams of Lely and Nassau Mountains was expected, but the high number of potentially new (and endemic?) species in Nassau Mountains was exceptional. A diet consisting of filamentous (red) algae, diatoms and fine detritus, low fecundity (3-7 large, mature eggs per female), and sedentary habits make Harttiella crassicauda of Nassau Mountains highly vulnerable to human impact on its habitat (e.g. mining-related siltation and sedimentation, and habitat loss). The steep slopes bordering the Nassau Plateau apparently act as biogeographic barriers that prevent the dispersal of fishes from one high-altitude stream to the other streams on the plateau. For example, Harttiella crassicauda from the central branch of Paramaka Creek (IJskreek) differed morphologically from H. crassicauda collected in a northern branch of Paramaka Creek (the two tributaries joining each other in the foot hills of Nassau Mountains). A new loricariid species (nicknamed 'big mouth') from the northern branch of Paramaka Creek was not collected in the central branch (IJskreek), notwithstanding extensive collection efforts at the latter site. Paramaka Creek with its large catchment on the plateau had most of the unique fish species of Nassau Mountains and should be carefully protected. However, other high-altitude streams of Nassau Mountains were sampled only once (or not at all) and they should be inventoried more thoroughly in the future. The genus Lithoxus of high-altitude streams of Nassau Mountains should be studied in detail including analysis of its DNA. Both Nassau and Lely Mountains are concessions of bauxite mining companies. In the foot hills, small- and large-scale gold mining, forestry and shifting cultivation threaten the pristine wilderness character of the forest and streams. Because of its geographical location close to the densely populated coastal plain and its accessibility by road, these threats have a more immediate character in Nassau Mountains as compared to Lely Mountains. The Surinamese government should collaborate with local and international organizations and the concession holder in a comprehensive effort to protect Nassau Mountains and preserve its unique flora and fauna for future generations.