Free-living nematode assemblages downstream from a pulp and paper mill in Humber Arm, Newfoundland

The composition of benthic nematode populations was studied at two depths a t each of three sites 0.8, 2.0 and 4.0 km downstream from a pulp and paper mill situated at the head of the Humber Arm, Corner Brook. Nematodes from 2 9 genera were identified. Extremely high relative abundance of Monhystera w as observed at both depths at the site (DeGrouchy Point) closest to the mil l. At the other two locations (Church Cove and Birchy Point), population co mpositions were found to differ both between each location and between dept hs. Population diversity, evenness and richness values decreased with incre asing proximity to the mill. The Maturity Indices at Church Cove and Birchy Point were similar, and both were higher than those at DeGrouchy Point. In dications were that moderate amounts of purely organic detritus associated with sewage outfall had a somewhat positive impact on the population measur es such as diversity and richness, while the opposite was true for the mill effluent which contained chemical pollutants in addition to organic waste.