Seasonal dynamic of benthic Macroinvertebrates in selected equatorial forest streams

Abstract

A study aimed at assessing the seasonal dynamics of benthic macrofauna in the Mvila Division. Sampling of benthic macroinvertebrates was carried out using the multi-habit/indat approach (Stark et al. 2001), using a 30 cm square dip net fitted with a 400 µm conical mesh at 50 cm depth. A total of 7828 individuals were identified and counted. 3404 individuals  of benthic macroinvertebrates (43.48% relative abundance) were counted in long dry season (LDS), 1839 individuals  (23.49% relative abundance) in short rainy season (SRS), 1696 individuals  (21.67% relative abundance) in long rainy season (LRS) and 889 individuals  of benthic macroinvertebrates (11.36% relative abundance) in short dry season (SDS). In terms of diversity, a total of 174 taxa were identified: 111 in the LDS, 106 in the SRS, 92 in the LRS and 51 in the SDS. Shannon and Weaver's diversity index showed the lowest value in SDS, while its highest value was recorded during SRS, as was Pielou J Equitability index. Jaccard's similarity index shows that the sampling seasons differ from one another. The frequency of occurrence of benthic macroinvertebrates taxa shows the predominance of rare taxa in all seasons. The similarity index suggests that the seasons differ from one another. In the end, the LDS had the lowest species richness and the highest abundance, while the SRS had the highest diversity value according to Shannon and Weaver.