Short-term Effect on the Metabolism of Lotic Benthic Communities Following Experimental Acidification

Abstract

Short-term quantitative change in whole benthic community metabolism was observed at low pH. From the beginning until 38 d after acidification (with one exception), oxygen uptake was significantly lower in the acidified channels (pH 4.0, pH 4.0 + 0.4 mg Al∙L⁻¹) than in the control (pH 6.3–6.9, 0.05–0.13 mg Al∙L⁻¹). By the midpoint of acidification (45 d) until the end (85 d), oxygen uptake of the communities in treated channels did not differ from the control. However, at the end of the experiment in acidified channels, the biomass of macroinvertebrates and algae were higher and the number of macroinvertebrates was lower than in the control. The lower total community metabolism may result in a lower decomposition rate, as organic matter in sediment was higher in acidified channels with or without aluminum (58 and 54%, respectively) than in the control (46%).