Seasonal Changes in Macroinvertebrates Abundance & Physicochem1stry of Moussa Stream Bida, Nigeria

Abstract

Seasonal changes in macroinvertebrates abundance and physiochemistry of Moussa Stream, Bida Nigeria, were studied monthly from January to August 2017. Macroinvertebrates were sampled using modified kick sampling techniques. Three different sampling stations were selected along the course of the Stream; The results from the stream showed that water temperature (24.9-27.5°C), Depth (14.7-45.8cm), Flow velocity (0.14- 0.23m/s), Biochemical oxygen demand (2.0-7.0mg/L), pH (6.33-8.6), Conductivity (20- 63|j/cm), Alkalinity (8-30mg/L), Turbidity (61-285NTU), Nitrate (0.87-3.85mg/L) and Phosphate (0.31-1.01 mg/L) were within the maximum permissible limit except Dissolved oxygen (3.1-10mg/L). All the parameters showed no significant difference (p>0.05) among all the sampling stations except depth and flow velocity which differed significantly (p<0.05) among all the sampling stations. Temperature, depth and flow velocity showed no significant difference among sampling season. pH, DO, BOD5, Turbidity Conductivity Alkalinity, Nitrate, and Phosphate differed significantly among seasons. A total of 477 individuals from 30 species and 20 families of invertebrates were recorded. The overall macroinvertebrates recorded from station 1, 2 and 3 were 167(35.01%), 151(31.65%) and 159(33.33%). Overall, there was significant difference (p<0.05) in number of individuals between the sampling stations. The abundance of taxonomic level revealed that Coleopterans, Odonata and Hemipterans were the most common groups encountered. Ephemeroptera were sparingly found in all stations. Other groups were also found in good numbers. The percentage and total number of individuals of macroinvertebrates recorded during the study period shows 66.25% (316 individuals) in dry season and the remaining 33.75% (161 individuals) were recorded in rainy season. CCA result correlated positively between species abundances and measured environmental variables. Low density of pollution sensitive macroinvertebrates groups and the deteriorating water quality were implications of pollution stress caused by anthropogenic activities.