Determining Sources of Water to Great Lakes Coastal Wetlands: A Classification Approach

Abstract

Water and associated nutrients can enter freshwater and marine coastal wetlands from both watershed and offshore sources. Identifying the relative contribution of these potential sources, and the spatial scale at which sources are influenced by anthropogenic activities, are critical steps in wetland protection and restoration. We developed a hydrology-based classification scheme for Great Lakes coastal wetlands for the purpose of identifying dominant hydrologic influences and water sources. Classes were determined through analysis of data quantifying hydrologic linkages to lake (seiche) and watershed (watershed area, tributary discharge) in 57 wetlands distributed along the U.S. shoreline of the Laurentian Great Lakes. Wetlands were partitioned into four classes of hydrology that were predicted to differ in sources of water. Source water predictions were tested by comparing Chloride (Cl -) concentrations in wetland, lake, and tributary waters of the wetlands in each class. Results confirmed that classification based on quantitative hydrology data was successful in identifying groups of wetlands with similar water sources. Correlations between wetland Cl -, an indicator of anthropogenic disturbance, and agricultural and urban land uses suggest that differences among classes in water sources resulted in differences in the scale at which wetlands were connected to and influenced by landscapes.

An exploratory investigation of the landscape-lake interface: Land cover controls over consumer N and C isotopic composition in Lake Michigan rivermouths

“…If these rivermouths were being considered as coastal wetlands, then all would fall in the "Tributary Dominated" area of the wetland classification scheme proposed by Morrice et al (2011) and this may suggest internal production is less important than external subsidies (especially from the river). If the suspended organic carbon (POC) concentrations measured here (in the lake and rivers) are representative of the suspended POC in general, then river and lake POC likely contributes a large portion of the total organic C budget in these rivermouths.…”

Watershed and lake influences on the energetic base of coastal wetland food webs across the Great Lakes Basin

“…We have shown that coastal wetlands differ in the extent to which their food webs are influenced by their watersheds and their lakes. Great Lakes coastal wetlands have also been shown to differ in the degree to which their watersheds influence wetland water quality; wetland water quality responses to landscape disturbance can be predicted by quantifying relative hydrologic inputs from tributary vs. lake (Morrice et al, 2011). Therefore, for wetlands strongly influenced by their watersheds, land use management at the watershed scale should be effective in managing wetland condition.…”

Groundwater in Crisis? Addressing Groundwater Challenges in Michigan (USA) as a Template for the Great Lakes

“…Frequently, impervious surfaces associated with developed areas reduce infiltration, thus decreasing groundwater recharge and increasing surface runoff [110,111]. The consequence of this could be altered sources, quantity, timing, and quality of water fluxes to coastal wetlands [112]. Additionally, the specific design of stormwater infrastructure and underlying conditions (soils, aquifer depth) can result in development either decreasing or increasing groundwater recharge [113].…”