Abstract
Despite their great interest for the integrated management of water resources, information on the ecology of aquatic oligochaetes is still sketchy in Cameroon. The present study aims at contributing to the knowledge on the distribution, microhabitat and life history of Naididae tubificids taxa in some eight water bodies of the city of Yaoundé. A total of 132 samples were analysed and the morphospecies Branchiura spp. and Limnodrilus spp. were identified. The most abundant species were Branchiura spp. with 2035 individuals versus 880 Limnodrilus spp. Both of them demonstrate low seasonal variations. It appeared that, these annelids are more abundant on clay-rich soils than on sand and the herbarium. Assessment of the organic pollution index indicates an organic pollution of the sampled waters ranging from moderate to high (3.67-2). The redundancy canonical analysis shows that Branchiura spp. are more present in saline waters revealing high organic pollution factors variables. During the study period, some 10 individuals of Limnodrilus spp. presented a shrunken tail. That reveals a strong environmental pressure due to the action of predators or the presence of heavy metals in the aquatic system evaluated. All these characteristics indicate a high pollution and predation pressure in the milieu. Key words: Annelids oligochaete, ecology, bottom nature, polluted water.
Highlights
In the city of Yaoundé, which is the political capital of Cameroon, surface water is used for the production of drinking water, irrigation of crops in urban agriculture, fish farming activities, recreation, and the list is very extensive
This town is subject to an equatorial climate that is characterized by four seasons: the short rainy season (SRS) from March to June, the short dry season (SDS) from July to August the long rainy season (LRS) from September to November, and the long dry season (LDS) from late December to February (Sighomnou, 2004)
The physico-chemical results of our sampling points are presented in Table 2, Table 3 and Table 4
Summary
In the city of Yaoundé, which is the political capital of Cameroon, surface water is used for the production of drinking water, irrigation of crops in urban agriculture, fish farming activities (aquaculture), recreation, and the list is very extensive. Due to uncontrolled urbanization, these waters are subject to very high pollution (Kemka et al, 2004; Zébazé et al, 2006; Ebang et al, 2012; Ajeagah et al, 2014; Kapso et al., 2018; Ngong et al, 2019). Almost 82.8% of the untreated wastewater is directly discharged into the environment (Ngambi, 2015) and this alters the quality of the natural resource. For a good monitoring of the surface water bodies, aquatic oligochaetes can be an important ecological.
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