Ecological Influence of Organic Pollution on the Distribution of Benthic Macroinvertebrates in Some Control Forest Watercourses in Cameroon

Monitoring of water quality and distribution of some benthic macroinvertebrates was carried out in a few control watercourses in the Mefou watershed, from August 2022 to June 2023 with the aim of identifying some ecological factors that influence the distribution of benthic organisms in forest areas. The evaluation of granulometric and physicochemical quality was carried out following the appropriate methods and the collection of benthic organisms following the multihabitat approach. The analysis of the particle size parameters shows that the coarse fraction dominates all the points explored, although the beginning of siltation was observed in the middle part of the Abouda and Fam rivers. Physico-chemical analyses revealed a relatively stable environment with well-oxygenated water, low values of organic pollution indicator parameters and low and constant temperatures throughout the watersheds. The analysis of the biological structure shows a total of 8483 individuals collected, all belonging to the arthropod phylum and the insect class. From the orders obtained, Hemiptera dominate the benthic fauna with 6 identified families. The organisational structure of the benthic community was analysed through the calculation of diversity and fairness indices and allows us to affirm that the benthic macroinvertebrate community is diverse and well organised.&nbsp

Impact of the anthropogenic activities on the diversity and structure of benthic macroinvertebrates in tropical forest stream

The diversity and structure of benthic macroinvertebrates related to some physico-chemical parameters were studied in the Konglo stream, an affluent of the Nyong river in Cameroon. The benthic macroinvertebrates were collected at three stations according to multihabitat the approach and physic-chemical parameters were sampled and analyzed using classic methods between February 2014 and August 2014. During this study, 1969 individuals belonging to 3 phyla, 7 classes, 16 orders, 63 families and more than 90 genera were sampled. The class of Insects, including 9 orders, 54 families and more than 79 genera, predominates with 74.81 % of the relative abundance, followed by the class of Decapods regrouping 21.94 % of the individuals distributed in 1 order, 2 families and 2 genera, however less varied. The other classes (Achaeta, Oligochaeta, Bivalvia, Gastropoda and Arachnida) represent only 3.25 % of relative abundance. The spatial variation of taxonomical richness shows a decrease of the diversity from upstream to downstream as well as the Ephemeroptera-Plecoptera-Trichoptera (EPT) index. Moreover, the Sörensen similarity index indicates dissimilarity between the station K3 and the two others stations. Otherwise, the rank-frequency diagram of Frontier and the Shannon and Weaver index show that the structure of benthic macroinvertebrates is in ecological starting succession in upstream and middle while it is closed to ageing in downstream

Preliminary Study on Water Quality and Heteropterans Diversity in A Semi-Urban Stream (Central Region of Cameroon)

A study was conducted in the Konglo stream for six months to make an inventory of aquatic heteroptera, following a monthly sampling frequency. Some hydrological and physicochemical parameters such as water width, current velocity, and water flow, water temperature and pH, electrical conductivity, dissolved oxygen, total hardness, phosphates, nitrates, and ammonia were measured according to standard methods. For an inventory of the heteropterans, the multihabitat approach was used during sampling, but only heteropterans representing 3.15 % of total abundance are considered in this study. The hydrological variables were different in each station. The water width and flow were increased from upstream to downstream. The results showed that pH, total hardness, nitrites, phosphates, and ammonia values ​​were weak and no significant differences were observed. Among physicochemical variables, only dissolved oxygen and electrical conductivity were different between upstream and downstream. The conductivity increased from upstream to downstream while the dissolved oxygen was very low downstream. 62 individuals were collected and counted belonging to 11 taxa, the most abundant being Ranatra linearis. The other taxa such as Anisops sp., Aphelocheirus aestivalis, Gerris sp., Gerridae Nd., Hydrometra sp., Ilyocoris cimicoides, Naucoris sp., Nepa sp., Notonectidae Nd., and Velia sp. were poorly represented. High abundance was recorded at the upstream (38 individuals), but the taxonomic richness (3 taxa) and diversity (0.24 bits/ind) remain low, unlike the stations located downstream (7 taxa and 1.82 bits/ind)