A Basin-Wide Survey of Coastal Wetlands of the Laurentian Great Lakes: Development and Comparison of Water Quality Indices

Abstract

Coastal wetlands of the Laurentian Great Lakes are vital habitats for biota of ecological and economic importance. These habitats are susceptible to water quality impairments driven by runoff from the landscape due to their location along the shoreline. Monitoring of the overall status of biotic and abiotic conditions of coastal wetlands within the Great Lakes has been ongoing for over a decade. Here, we utilize measurements of aquatic physicochemical and land cover variables from 877 vegetation zones in 511 coastal wetland sites spanning the US and Canadian shorelines of the entire Great Lakes basin. Our objective is to develop water quality indices based on physicochemical measures (Chem-Rank), land use/land cover (LULC-Rank), and their combined effects (Sum-Rank and Simplified Sum-Rank), for both vegetation zones and wetland sites. We found that water quality differed among wetland vegetation types and among Great Lakes regions, corroborating previous findings that human land use alters coastal wetland water quality. Future monitoring can use these straightforward, easy-to-calculate indices to assess the abiotic condition of aquatic habitats. Our data support the need for management efforts focused on reducing nutrient and pollution loads that stem from human activities, particularly in the developed southern portions of the Great Lakes basin.

Response of Typha to phosphorus, hydrology, and land use in Lake Ontario coastal wetlands and a companion greenhouse study

“…Modeling by Hamlin et al (2020) showed agricultural fertilizer to be a major nutrient source along the southern shore of Lake Ontario. Agricultural and urban land use in wetland catchments of the Great Lakes has been shown to affect nutrient enrichment, water clarity, and sediment quality (Crosbie and Chow-Fraser 1999;Trebitz et al 2007;Morrice et al 2008;Robertson and Saad 2011;Harrison et al 2020). In a basin-wide study, Lougheed et al (2001) concluded that the proportion of agricultural and urban land in wetland watersheds was a statistically significant predictor of water quality.…”

Nitrogen addition and fungal symbiosis alter early dune plant succession

“…The U.S. Great Lakes coastal region has high N enrichment due to agricultural, atmospheric, and point-source inputs (Morrice et al 2008 ; National Atmospheric Deposition Program 2022 ). For example, atmospheric N deposition, especially the concentration of NH 4 + , into Great Lakes ecosystems have increased by 400% from historic levels (Du et al 2014 ), while dissolved inorganic N in Great Lakes coastal wetlands has risen as a direct result of row-crop agriculture and urbanization in the region (Morrice et al 2008 ; Harrison et al 2020 ). Understanding potential changes to Great Lakes ecosystems is essential for conservation of these ecosystems in the future.…”

Influences of seasonality and habitat quality on Great Lakes coastal wetland fish community composition and diets

“…Efforts to assess, monitor, and restore GLCW have gained momentum over the last several decades (Smith et al 1991;Loftus et al 2004;Uzarski et al 2017a;Harrison et al 2019). The Great Lakes coastal wetland monitoring program (CWMP) has assessed over a thousand GLCW during the last decade and developed indices to quantify wetland condition.…”

“…The Great Lakes coastal wetland monitoring program (CWMP) has assessed over a thousand GLCW during the last decade and developed indices to quantify wetland condition. One such index, the CWMP water quality-land use indicator (hereafter the WQ-LU indicator; referred to as "SumRank" in earlier publications such as Cooper et al 2018, and Kovalenko et al 2019, incorporates many in situ water quality measurements and adjacent land-cover variables into a single score (Uzarski et al 2017a;Harrison et al 2019). Lower scores indicate poor wetland quality, while higher scores indicate less disturbed conditions.…”

“…While land-use/land-cover is often used to predict the potential for water quality impairments (e.g., Danz et al 2007), the WQ-LU indicator allows one to also incorporate the in situ water quality of a site. Harrison et al (2019) used the WQ-LU indicator to show that GLCW water quality generally decreases with decreasing latitude across the Great Lakes basin. The WQ-LU indicator has also been used to calibrate other habitat quality indices, particularly the CWMP's fish-based index of biotic integrity (Cooper et al 2018).…”