Depth-related patterns in benthic community condition along an estuarine gradient in Chesapeake Bay, USA

摘要: Abstract We tested whether macrobenthic community condition varies significantly with water depth in a variety of regions Chesapeake Bay, USA. Benthic was characterized using the Index Biotic Integrity (B-IBI) previously developed for Bay. applied two thresholds intended to emphasize ecological importance and/or anthropogenic impacts upon shallow-water regions. The first threshold 2 m emphasizes restoring and supporting submerged aquatic vegetation while second 4 m zone maximum impact natural ecosystem functions. An priori expectation is that benthic may worsen increasing depth, specifically (1) where column stratification at results prolonged low dissolved oxygen levels or (2) net deposition higher hydrophobic, sediment-bound contaminants. Samples collected from major tributary York River estuary, spanned entire salinity range tidal freshwater polyhaline. also data Virginia Mainstem Bay Southern Branch Elizabeth River. These polyhaline are as having best worst At scale system, there were no significant differences depth. However, regions, mesohaline polyhaline, had effects shallowest different other For region worse better comparing three No depth-related B-IBI found additional strata, lowest degradation branch River, by highest degradation. conclude state subtidal communities adequately randomly sampling all depths without further into shallow deeper