Abstract
BackgroundFour central Sahara mountainous massifs provide habitats for relict populations of fish. In the Adrar of Mauritania all available data on the presence and distribution of fish come from pre-1960 surveys where five fish species were reported: Barbus pobeguini, Barbus macrops, Barbus mirei, Sarotherodon galilaeus, and Clarias anguillaris. Since 1970, drought has had a severe impact in the Adrar where rainfall decreased by 35%. To investigate whether the relict populations of fish have survived the continuing drought, a study was carried out from 2004 to 2008.Methodology/Principal FindingsAn inventory of perennial bodies of water was drawn up using a literature review and analysis of topographical and hydrological maps. Field surveys were carried out in order to locate the bodies of water described in the literature, identify the presence of fish, determine which species were present and estimate their abundance. The thirteen sites where the presence of fish was observed in the 1950s -Ksar Torchane, Ilij, Molomhar, Agueni, Tachot, Hamdoun, Terjit, Toungad, El Berbera, Timagazine, Dâyet el Mbârek, Dâyet et-Tefla, Nkedeï- were located and surveyed. The Ksar Torchane spring -type locality and the only known locality of B. mirei- has dried up at the height of the drought in 1984, and any fish populations have since become extinct there. The Timagazine, Dâyet el Mbârek and Dâyet et-Tefla pools have become ephemeral. The Hamdoun guelta appears to be highly endangered. The fish populations at the other sites remain unchanged. Four perennial pools which are home to populations of B. pobeguini are newly recorded.Conclusion/SignificanceThe tropical relict fish populations of the Adrar mountains of Mauritania appear to be highly endangered. Of thirteen previously recorded populations, four have become extinct since the beginning of the drought period. New fish population extinctions may occur should low levels of annual rainfall be repeated.
Highlights
The presence of fish in the Sahara, evidence of the world’s hottest desert humid past during the Holocene period, was recognised in the first Saharan exploration expeditions in the early 20th century [1,2,3,4]
On the southern fringes of the Sahara, relict fish fauna survive in the Tagant of Mauritania and in the Ennedi of Chad
Sixteen species and sub-species of fish have managed to survive in the central Sahara, most commonly in a very low number of watering places, sometimes in a single spring or guelta (Table 1)
Summary
The presence of fish in the Sahara, evidence of the world’s hottest desert humid past during the Holocene period, was recognised in the first Saharan exploration expeditions in the early 20th century [1,2,3,4]. Sixteen species and sub-species of fish have managed to survive in the central Sahara, most commonly in a very low number of watering places, sometimes in a single spring or guelta (Table 1). These species are the following: Barbus macrops Boulenger, 1911, Barbus pobeguini Pellegrin, 1911, Barbus deserti Pellegrin, 1909, Barbus bynni occidentalis Boulenger, 1911, Barbus callensis biscarensis Boulenger, 1911, Labeo parvus Boulenger, 1902, Labeo niloticus (Forsskal, 1775), Raiamas senegalensis (Steindachner, 1870), Clarias anguillaris (Linnaeus, 1758), Clarias gariepinus (Burchell, 1822), Epiplatys spilargyreius (Dumeril, 1861), Hemichromis bimaculatus Gill, 1862, Sarotherodon galilaeus galilaeus (Linnaeus, 1758), Sarotherodon galilaeus borkuanus (Pellegrin, 1919), Astatotilapia desfontainesi (Lacepede, 1803) and Tilapia zillii (Gervais, 1948) [3,4,5,8,10]. To investigate whether the relict populations of fish have survived the continuing drought, a study was carried out from 2004 to 2008
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