Macroinvertebrate communities in Detroit River coastal wetlands: association to water quality status and tributary inputs.

Abstract

Abstract The Detroit River is a Great Lakes Area of Concern with five monitored wetlands in the Canadian jurisdiction. Habitat assessments have indicated degraded conditions within two adjoining tributaries, Turkey Creek and River Canard. At these tributary junctions, submerged macrophyte beds extend into the channel where tributary inflow may be altering benthic macroinvertebrate communities. We first examine inter-wetland differences for resemblance to water quality status. We had found by NMDS and PERMANOVA wetland communities had not resembled water quality index scores. Second, we perform an intra-wetland comparison for Turkey Creek and River Canard to analyze for differences along tributary inputs. Wetland communities were delineated by position into upstream, downstream, and tributary plume strata and analyzed by NMDS and PERMANOVA. Additionally, to detect potentially impaired sample sites along tributaries, a multivariate reference condition approach was applied with a habitat standardization to contrast River Canard and Turkey Creek to reference wetlands. At neither River Canard nor Turkey Creek we observed significant tributary influence on river communities but had found the Turkey Creek tributary communities significantly differed from the channel communities. Multiple lines of evidence suggest community impairment in Turkey Creek likely from upstream waters rather than tributary inputs. This study highlights that a-priori site selection by wadable depths and vegetation types is limited in detecting impairment in coastal wetlands who do not conform to these profiles.