Ecological status of a tropical river in Niger delta area of Nigeria, using aquatic insects

Freshwater ecosystems are the major source of water, being used for domestic, agricultural and industrial purposes. Water bodies are subjected to anthropogenic activities leading to degradation of the water quality. The aim of this study is to assess the health status of Isiokpo River. Aquatic insects were sampled from March to August 2017. Physico-chemical parameters were examined using standard laboratory procedures. A total of 21 taxa comprising of 543 individual insects were recovered. Stations 1, 2 and 3 recorded 53.41, 21.36 and 25.23% of the insect population respectively. A total of six Ephemeroptera, Plecoptera and Trichoptera (EPT) species were recorded in the study. The %EPT was 28.57, 33.33 and 30.77% in station 1, 2 and 3 respectively. There were significant differences in the distribution of dissolved oxygen, phosphate, nitrates transparency, flow velocity, and total dissolved solids across the various stations (p<0.05). The reduced level of dissolved oxygen in station 3 as well the dominance of Chironomus sp. are indications of the impact of anthropogenic activities. The study showed that the Isiokpo River is relatively unhealthy.   Key words: Aquatic insects, Biomonitoring, Freshwater, Ephemeroptera, Plecoptera, Trichoptera, Water quality.