Assessing the potential of macroinvertebrates and coliform bacteria as bioindicators of a tropical aquatic ecosystem in the southwest region of Cameroon

Abstract

This research aimed to assess the bioindicator potential of bacterial coliforms and benthic macroinvertebrates of the Ndongo stream, an urban stream on the southeast slope of Mount Cameroon. For this purpose, macroinvertebrates were collected monthly from November 2021 to May 2022 at three sampling stations of the Ndongo stream. At each sampling station, temperature, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), salinity, pH, flow velocity, flow rate and total coliforms were measured. Results revealed that there was a significant fluctuation in water hydrological, physico-chemical and microbiological parameters across stations (p < 0.05). Furthermore, a total of 917 macroinvertebrates were collected at the 3 stations, but their community structure differed across sampling sites. The values of the Shannon–Weaver index indicated a less diversified community with the dominance of a few species. The bacterial coliform count was above the WHO maximum acceptable concentration (i.e. 0 CFU per 100 ml) in all the sampling stations, hence compromising the use of the stream for domestic purposes. Water abiotic variables had less effect on total coliform count (R² = 0.54; F = 1.42, df = 11, p = 0.29). Macroinvertebrate families such as Planariidae, Gerridae, Dytiscidae, Veliidae, Nepidae, Pseudostigmatidae, Dipterocarpaceae had strong association with water abiotic variables. The study confirmed the potential use of benthic macroinvertebrates as bioindicators of water abiotic variables in tropical freshwater ecosystems.