Ref ID : 3324
Jonas M. Svensson, Alex Enrich-Prast, and Lars Leonardson; Nitrification and denitrification in a eutrophic lake sediment bioturbated by oligochaetes. Aquatic Microbial Ecology 23:177-186, 2001
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The influence on nitrification and denitrification of oligochaete Limnodrilus sp. and Tubifex tubifex bioturbation was determined in eutrophic lake sediment from the Basin of Lake Ringsjon in southern Sweden. Nitrification and denitrification activity was compared in sieved and in undisturbed sediment cores in laboratory mesocosms at 2 different concentrations of nitrate. Nitrification and total denitrification were positively correlated to oligochaete biomass between 0 and 4 g dry weight m-2 at both 33 and 268 µM nitrate in the inflowing water. Denitrification (dw) was relatively more stimulated by the oligochaetes at high concentration of nitrate in the overlying water than at low nitrate concentrations. Though nitrification was enhanced by oligochaetes, this tended to reach a maximum between 3 and 5 g of oligochaete dry weight m-2. Comparison of the enhancement of denitrification by oligochaetes with other similar studies of denitrification in eutrophic sediment bioturbated by tube-dwelling chironomids indicates that at a similar biomass oligochaetes are less effective at mobilizing nitrate to deeper sediment layers. This is explained by the different ways oligochaetes and tube-dwelling chironomids bioturbate the sediment. Sieving and homogenising the sediment had no pronounced effect on denitrification and nitrification compared to undisturbed sediment.