Human Influences on Water Quality in Great Lakes Coastal Wetlands

Abstract

A better understanding of relationships between human activities and water chemistry is needed to identify and manage sources of anthropogenic stress in Great Lakes coastal wetlands. The objective of the study described in this article was to characterize relationships between water chemistry and multiple classes of human activity (agriculture, population and development, point source pollution, and atmospheric deposition). We also evaluated the influence of geomorphology and biogeographic factors on stressor-water quality relationships. We collected water chemistry data from 98 coastal wetlands distributed along the United States shoreline of the Laurentian Great Lakes and GIS-based stressor data from the associated drainage basin to examine stressor-water quality relationships. The sampling captured broad ranges (1.5-2 orders of magnitude) in total phosphorus (TP), total nitrogen (TN), dissolved inorganic nitrogen (DIN), total suspended solids (TSS), chlorophyll a (Chl a), and chloride; concentrations were strongly correlated with stressor metrics. Hierarchical partitioning and all-subsets regression analyses were used to evaluate the independent influence of different stressor classes on water quality and to identify best predictive models. Results showed that all categories of stress influenced water quality and that the relative influence of different classes of disturbance varied among water quality parameters. Chloride exhibited the strongest relationships with stressors followed in order by TN, Chl a, TP, TSS, and DIN. In general, coarse scale classification of wetlands by morphology (three wetland classes: riverine, protected, open coastal) and biogeography (two ecoprovinces: Eastern Broadleaf Forest [EBF] and Laurentian Mixed Forest [LMF]) did not improve predictive models. This study provides strong evidence of the link between water chemistry and human stress in Great Lakes coastal wetlands and can be used to inform management efforts to improve water quality in Great Lakes coastal ecosystems.

Partitioning Vegetation Response to Anthropogenic Stress to Develop Multi‐taxa Wetland Indicators

“…The CSI has been demonstrated to be strongly related to characteristics of diatom, bird, fish, amphibian, and coastal wetland vegetation communities (Reavie et al 2006, Brazner et al 2007). The constituent PCs of the CSI were also significantly related to coastal water chemistry (total P, total N, dissolved inorganic N, total suspended solids, and Cl À ) measured in 98 Great Lakes coastal wetlands (Morrice et al 2007). We adopted the CSI as an independent measure of watershed-scale anthropogenic stress based on its proven utility in prior studies, and did not attempt to evaluate or modify it.…”

“…Anthropogenic stressors may be activities that have occurred within the boundaries of the wetlands themselves, directly affecting wetland vegetation and function, or they may result from offsite activities in the landscape adjacent to the wetland, indirectly affecting coastal wetlands through fluxes of water, nutrients, and contaminants (Johnston 1994). An index of cumulative anthropogenic stress was developed for watersheds on the U.S. side of the Great Lakes basin by Danz and coworkers (2007) and was verified to be related to coastal wetland water quality (Morrice et al 2007) and biotic characteristics (Reavie et al 2006, Brazner et al 2007). Other studies have also confirmed that wetland vegetation is affected by upslope agriculture and urbanization (Findlay and Houlahan 1997, Mensing et al 1998, Galatowitsch et al 2000, Lougheed et al 2001.…”

Multiscale landscape and wetland drivers of lake total phosphorus and water color

“…We defined two human land-use variables as agriculture (including both pasture and row cropping) and urban land uses. Although there are other human disturbances that affect lakes, we use agriculture and urban land uses as indicators of many of the major human effects that influence water chemistry (Morrice et al 2007).…”

Valuation of Ecosystem Services from Wetlands Mitigation in the United States

“…Studies have shown that wetlands properly constructed and maintained could be effective for protecting water quality [25,26]. With several water quality stressors such as agriculture [27], urban development, population growth, and atmospheric deposition [28], the value of wetlands for water quality improvement is not unrealistic. Moreover, wetlands are central components of aquatic ecosystems, an interdependence that provides strong scientific justification for policies that make a connection between clean water and the protection of wetland ecosystems [29].…”