Dynamics of benthic macroinvertebrates in created wetlands receiving wastewater

This paper presents results of a study on the status and dynamics of benthic macroinvertebrates in a wetland constructed for wastewater treatment in Nairobi (Kenya), conducted for 16 weeks during the period between December 1995 and March 1996. Seventeen species of macroinvertebrates were recorded in the wetland. Species richness in the wetland was 9.6 ± 1.3 while species diversity index was 0.466. Mean pH and dissolved oxygen increased gradually from the intake point to the outlet while the BOD₅, suspended solids and free and saline ammonia decreased as the wastewater flowed throughout the wetland. The benthic macroinvertebrate community was poorly developed while microbial community appeared to be well developed. It was evident that the community structure improved with the purification of wastewater along the wetland. As discussed in the paper, aquatic benthos are crucial to wetlands ecosystems function and they are potential indicators of health of these ecosystems.