A study to determine the response of nematodes as bio-indicators of environmental alterations was carried in the New Calabar River in the Niger Delta. Samples were randomly collected from the benthic zone of the River using the modified Baermann’s technique. The study yielded sixteen (16) nematodes belonging to three (3) families and eight (8) species. The nematode speciation include: The nematode speciation include: include: Aphelenchoidesritzemabosi. 1 (6.25%), Dorylaimusstagnalis 2(12.5%), Mononchusaquaticus 1(12.5%), Plectus spp.(12.5%), Pratylenchusspp 2(12.5%), Rhabdolaimus spp. 1(6.25%), Tylenchusdavainei 2(12.5%) and Tylenchorhynchusdubius 4(25%). The low species richness and abundance observed in the study were attributed to ecological factors such as seasonality, ecological characteristics of the river and anthropogenic activities. The influx of organic pollutants and other municipal wastes were associated with the occurrence of hydrobiont nematode species while the influx of run-offs into the river resulted to the occurrence of terrestrial nematodes; edaphobionts. However, the variability observed in the occurrence of the r-strategist and k-strategist nematodes depict a flux in ecological characteristics of the habitat. The study buttresses the sensitivity of nematodes to negligible ambient bio-physicochemical alterations in the ecosystem.