The macroinvertebrate fauna of Bear Creek, a 83 km stream which flows through six oxbow lakes, and two off-stream lakes in the same watershed was studied for two years. Bear Creek, a tributary of the Yazoo River in the Delta region of Mississippi, drains 330 km of Intensively cultivated agricultural land and carries a continuing sediment concentration during the rainy season of up to 1300 mg l−1. Benthic organisms were collected monthly from August, 1976 through August, 1978 at six stream stations and at 14 lake stations, across a variety of substrates, and at depths ranging from 0.5 to 6.5 m. In most lake and stream sections of the creek,Chaoborus(one species), Chironomidae (nineteen genera), and Oligochaeta (three species), dominated the benthos. Thirteen other genera of insects were represented as were Bryozoa (four genera), Mollusca (nine genera), Hirudinea (five genera), and Crustacea (three genera). There was continuous stress from high rates of sedimentation (up to seven cm yr−) as indicated by low taxa rlchness(s) and diversity (đ) at a majority of stations sampled. Most creek stations were subject not only to annual sedimentation and flushing but also to fluctuations in water level and drying. Secondary productivity varied greatly (one to 31 g dry wt m−2yr−1) and was almost totally dependent on three taxa of pollution tolerant organisms except In unstressed stream reaches. Low productivity in riverine lakes, when compared to stream sections was partially due to differences in species distribution in lotic and lentic habitats. The mayflyHexagenia bilineata, the clamSphaerium rhomboldeum, and the bryozoanPectinatella magnifica, responded negatively to environmental stresses Induced by seasonally high concentrations of suspended sediments.