Variability in physical and biological exchange between coastal wetlands and adjacent Great Lakes
Citation:
Trebitz, A., A. Cotter, J. Hoffman, G. Peterson, AND M. Sierszen. Variability in physical and biological exchange between coastal wetlands and adjacent Great Lakes. International Association for Great Lakes Research, Brockport, NY, June 10 - 14, 2019.
Impact/Purpose:
Among the important ecosystem services that coastal wetlands support are fishery production (feeding and sheltering species that provide recreational or commercial fishing) and water quality improvement (intercepting and processing watershed-derived nutrients and sediments before they enter the adjacent lake). This presentation examines the variability among wetlands in fish nutritional support and water quality processing and relates them to potential predictor variables using tools such as geochemical tracers and stable-isotope mixing models. Data sets used for the work derive both from recent research under SHC and from older research efforts under the former Water Quality RAP. Our results highlight the considerable complexity and diversity of coastal processes in the Great lakes and the challenge of generalizing the nature and extent of ecosystem services provided.
Description:
Hydrology is a major governor of physically-driven exchange among coastal wetlands and the adjacent Great Lake, whereas fish movement is a major governor of biologically-driven exchange. We examine variability in the nature and strength of these exchanges using data from 10 Lake Superior wetlands that span hydrogeomorphic configurations and landuse settings. Water quality data across the tributary wetland lake gradient is used to construct conservative-tracer mixing curves and deduce longitudinal nutrient uptake vs release patterns, and tissue stable isotope data from lake- and wetland-collected fish species is used to construct dual-isotope mixing models and deduce energetic reliance on wetland vs. lake-derived sources. Our data show that wetland uptake of watershed-supplied nutrients depends substantially on water residence time, whereas fish reliance on wetland food sources depends on a combination of species life history and availability of dissolved organic carbon. The across-wetland range in these factors is substantial but not concordant; wetland-nearshore exchanges thus varies along multiple dimensions of landscape setting that should be considered in coastal wetland protection, restoration, and management.