Human Influence on macroinvertebrate community structure within Nyando wetlands, Kenya



The study set out to investigate the changes in macroinvertebrate community along different disturbance gradients within Nyando wetlands with an aim of determining how macroinvertebrates in Nyando wetlands respond to human disturbances. Triplicate macroinvertebrate samples were collected monthly from October 2010 to April 2011 using a scoop net (500 µm mesh size) in three transects. They were sorted live, counted and identified to genus level. Water samples for total phosphorus and total nitrogen were collected and analyzed using standard methods. Physico-chemical parameters were taken in-situ using electronic meters. Macroinvertebrates were analyzed for richness, diversity, dominance, and abundance. The abundance and diversity was correlated with physico-chemical parameters using Pearson correlation analysis. Kruskal-Wallis test was used to test spatial differences in macroinvertebrate community and repeated measures ANOVA to test variation in water quality parameters. A total of 45 genera were identified with hemipterans dominating. The statistical analysis revealed significant spatio-temporal differences in macroinvertebrate abundance and water quality parameters. Macroinvertebrate abundance showed a strong negative correlation with nutrient levels. Sites with higher disturbance recorded lower richness and abundance compared to the less disturbed sites. The results indicated that macroinvertebrates in Nyando wetlands respond to human disturbance and can be used to monitor ecological integrity of the wetland.