Linking Embeddedness and Macroinvertebrate Health in Two Southwest Ohio Streams

Environmental managers utilize a variety of tools when assessing lotic systems for stressors attributed to anthropogenic sources. Stream deposited sediment has been recognized as one of the major stressors affecting streams in the U.S. The detrimental effect on aquatic biota of sediment depositing within the interstitial spaces of stream substrate (embeddedness) has been established, yet lacking is an effective in situ method of quantifying embeddedness over short time periods. The goal of this research was to develop a short-term embeddedness (EMB) quantification method that can be linked to benthic macroinvertebrate health. Such a method would be a valuable tool when conducting biological and physical habitat assessments of wadeable streams and rivers. An in situ embeddedness chamber was developed to capture sediment deposited within the interstitial spaces of a uniformly sized substrate. Using sediment accumulation and macroinvertebrate colonization as endpoints, three exposure periods were evaluated (4, 7, and 14 days) on a small order stream (Honey Creek, New Carlisle, Ohio, USA) and a medium order stream (Stillwater River, Covington, Ohio, USA). The experiment was conducted during low flow conditions with little variation in flow, turbidity, and total suspended solids. Three treatment areas located downstream of the EMB chambers also were established to assess benthic macroinvertebrate colonization rates. Different levels of substrate disturbance (disturbed, slightly disturbed, and undisturbed) were mimicked by removing the embedded fine sediments. Embeddedness chamber results show correlations between newly deposited fine sediment and insect colonization rates. Measured percent embeddedness (USGS method) results at both sites were close to a natural stream condition.