Diversity and abundance of benthic macroinvertebrates in the Nima creek in Ghana
Biological monitoring and assessing the quality of fresh waters has been one of the environmental concerns for many countries of which Ghana is not exempted. This study was undertaken in the Nima creek in Ghana to assess the abundance, composition, and diversity of the benthic macro-invertebrate fauna. It also aimed at determining the quality of water in the creek based on the type of macroinvertebrates found in the creek. Samples were collected at 8 different riffles with a surber sampler. The benthic macroinvertebrates sampled consisted of 6 taxa and 5891 individuals belonging to Nematoda, Oligochaeta, Gastropoda, and Insecta classes. Chironomini were the predominant group with 99.04% on the average, followed by Psychoda sp (0.44%), Rhabitidae (0.26%), and Tubifex (0.26%) at the upstream stretch of the creek. The downstream was dominated by Chironomini forming 97.30% on the average, followed by Tubifex (1.52%), Rhabitidae (1.08%), and Psychoda sp (0.05%). The estimated diversity of the sampling area for both upstream and downstream was assessed by using the Simpson Diversity Index and was found to be 0.53, indicative of a fairly diversified community structure. The Family Biotic Index (FBI) was used to determine the water quality of the creek and found to be 9.92, which indicates severely polluted water. The distribution and occurrences of taxa in the upstream and downstream showed that the macro-invertebrates appeared in both reaches with the exception of Melanoides tuberculata, which occurred only at the downstream reach due to low current, the formation of rocky substratum, and the absence of riparian vegetation making it a suitable habitat.