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Project
The fish diversity of the Burundese rivers and the impact of human activities on this ichthyofauna
The objectives of this study were to </>compile the most uptodate information on the fish diversity of the Burundese river systems; to verifyand, if necessary, to revise taxa with taxonomic problems and to describe newly discovered species; </></>to determine the main environmental variables that are associated with fish distribution in the Upper Malagarazi River basin, and to identify potential threats to this fish biodiversity.</> </>
To achieve these objectives, the study was based on two major components: a biodiversity component and an</> ecological/environmental component:</></>
Biodiversity component:</></> Based on the literature and a review of the specimen holdings available in various natural history museums, a checklist of the riverine fishes of Burundi was compiled. A total of 15 </>families containing 42 genera and 90 described native species were reported for the country. </>
Further collecting efforts were undertaken in the Upper Malagarazi basin (Burundi) between December 2008 and February 2012. This resulted in a total of 75 species currently known from the area, including ten new records. Consequently, a key to the fish families occuring in the whole basin and to the species currently known from the Upper Malagarazi basin in Burundi was made. </></>
</>Four new species were found, including 'Barbus</>' sp."ascutelatus", Chiloglanis</> sp. "musasae" and Clariallabes </>sp. "nyaruhandazi", the description of which are being prepared, and 'Barbus'</> sp. "devosi", the description of which is in press. </>
An alphataxonomic revision of the cichlid genus Astatoreochromis</> was conducted.</>Whereas meristics clearly separated the populations from the Lake Victoria region </>(Astatoreochromis alluaudi</>) from those from the LakeTanganyika basin (A. vanderhorsti</> and A. straeleni</>), a clear difference could not be found between the latter two, represented respectively by populations from the Rusizi and the Malagarazi rivers. Astatoreochromis vanderhorsti</></> was therefore considered to be a junior synonymof A. straeleni</> and redescription of the two remaining valid species, i.e. A. alluaudi</> and A.straeleni</>, was given. </></>
Ecological/environmental component: </></>Investigations into the relationship between of fish distribution and environmental parameters were carried outon two selected sections of the Malagarazi and the Rumpungwe rivers. </>The importance of the riparian vegetation was demontrated. Three mormyrid species i.e.</> Gnathonemus longibarbis,</></> Pollimyrus nigricans</> and Marcusenius macrolepidotus</> significantly preferred the papyrus dominated section of the rivers while the forest bank section of the rivers haboured some rare fish species such as Synodontis melanostictus</> and S.</> cf. nigromaculatus</>, Distichodus maculatus</>, and Alestes macrophtalmus</>. </></>Our results revealed that the distribution of fish species in the Malagarazi section mainly responded to a gradient of a water quality parameter, conductivity, and a habitat parameter, the width of the river channel, whereas the Rumpungwe fish assemblage appeared less structured. The water conductivity was found to be very variable in the Malagarazi River (88.0 ̶ 537.0 µS/cm) and most likely fuelled by the wastewater input from the sugarcane plantations and the processingunit of a local refinery. Three genera of cyprinid fish i.e. Labeo</>, Labeobarbus</> and Opsaridium </>appeared to be the most affected as they were either completely absent (Labeobarbus</>) or very rare (Labeo</> and Opsaridium</>) in the catches in the area under influence of the sugar refinery. By contrast, 'Barbus' paludinosus</> and Brycinus imberi</>, appeared to be relatively tolerant, since they occurred in large proportions in that area. Since Cyperus papyrus</>, which dominates the vegetation in the area surrounding the sugar refinery, has been reported to act in swamps as a nutrient filter or trap, we suggest protecting or evenrestoring this vegetation in some areas to increase the river's selfpurification capacity. </>
The findings of this study have management implications for the current plans to create a natural reserve in the Upper Malagarazi basin.</>
To achieve these objectives, the study was based on two major components: a biodiversity component and an</> ecological/environmental component:</></>
Biodiversity component:</></> Based on the literature and a review of the specimen holdings available in various natural history museums, a checklist of the riverine fishes of Burundi was compiled. A total of 15 </>families containing 42 genera and 90 described native species were reported for the country. </>
Further collecting efforts were undertaken in the Upper Malagarazi basin (Burundi) between December 2008 and February 2012. This resulted in a total of 75 species currently known from the area, including ten new records. Consequently, a key to the fish families occuring in the whole basin and to the species currently known from the Upper Malagarazi basin in Burundi was made. </></>
</>Four new species were found, including 'Barbus</>' sp."ascutelatus", Chiloglanis</> sp. "musasae" and Clariallabes </>sp. "nyaruhandazi", the description of which are being prepared, and 'Barbus'</> sp. "devosi", the description of which is in press. </>
An alphataxonomic revision of the cichlid genus Astatoreochromis</> was conducted.</>Whereas meristics clearly separated the populations from the Lake Victoria region </>(Astatoreochromis alluaudi</>) from those from the LakeTanganyika basin (A. vanderhorsti</> and A. straeleni</>), a clear difference could not be found between the latter two, represented respectively by populations from the Rusizi and the Malagarazi rivers. Astatoreochromis vanderhorsti</></> was therefore considered to be a junior synonymof A. straeleni</> and redescription of the two remaining valid species, i.e. A. alluaudi</> and A.straeleni</>, was given. </></>
Ecological/environmental component: </></>Investigations into the relationship between of fish distribution and environmental parameters were carried outon two selected sections of the Malagarazi and the Rumpungwe rivers. </>The importance of the riparian vegetation was demontrated. Three mormyrid species i.e.</> Gnathonemus longibarbis,</></> Pollimyrus nigricans</> and Marcusenius macrolepidotus</> significantly preferred the papyrus dominated section of the rivers while the forest bank section of the rivers haboured some rare fish species such as Synodontis melanostictus</> and S.</> cf. nigromaculatus</>, Distichodus maculatus</>, and Alestes macrophtalmus</>. </></>Our results revealed that the distribution of fish species in the Malagarazi section mainly responded to a gradient of a water quality parameter, conductivity, and a habitat parameter, the width of the river channel, whereas the Rumpungwe fish assemblage appeared less structured. The water conductivity was found to be very variable in the Malagarazi River (88.0 ̶ 537.0 µS/cm) and most likely fuelled by the wastewater input from the sugarcane plantations and the processingunit of a local refinery. Three genera of cyprinid fish i.e. Labeo</>, Labeobarbus</> and Opsaridium </>appeared to be the most affected as they were either completely absent (Labeobarbus</>) or very rare (Labeo</> and Opsaridium</>) in the catches in the area under influence of the sugar refinery. By contrast, 'Barbus' paludinosus</> and Brycinus imberi</>, appeared to be relatively tolerant, since they occurred in large proportions in that area. Since Cyperus papyrus</>, which dominates the vegetation in the area surrounding the sugar refinery, has been reported to act in swamps as a nutrient filter or trap, we suggest protecting or evenrestoring this vegetation in some areas to increase the river's selfpurification capacity. </>
The findings of this study have management implications for the current plans to create a natural reserve in the Upper Malagarazi basin.</>
Date:1 Oct 2008 → 23 Nov 2012
Keywords:fishes, Burundi, Malagarazi, Rusizi, Africa, biodiversity
Disciplines:Geology, Aquatic sciences, challenges and pollution, Fisheries sciences, Animal biology
Project type:PhD project