Wetland Assessment: Beyond the Traditional Water Quality Perspective

Use of water chemistry or water quality data as the sole indicator to determine if aquatic ecosystems meet restoration objectives or Clean Water Act criteria is not possible for wetlands because surface water presence varies across wetland types. The 2011 National Wetland Condition Assessment (NWCA) assessed 967 sites representing 25,153,681 hectares of wetland across the conterminous US. Surface water could be collected at 537 sites, representing only 41% of the wetland population area and under‐representing particular wetland types. These results motivated us to introduce the concept of aquatic resource quality, the condition of an ecosystem based on the collective assessment of physical, chemical, and biological indicators, as the goal of monitoring and assessment of aquatic systems. The NWCA demonstrates the utility of aquatic resource quality, because the NWCA successfully reported on wetland condition using a biotic indicator (vegetation multimetric index) and the relative extent and relative risk of stressors using ten physical, chemical, and biological indicators to report on wetland resource quality. The NWCA also demonstrated that aquatic resource quality can be consistently evaluated regardless of surface water presence, thus substantiating our recommendation to employ aquatic resource quality as the goal of aquatic ecosystem monitoring and assessment.

Impact/Purpose

A comprehensive assessment of the ecological status of an ecosystem requires information about the physical, chemical, and biological integrity; however, scientists and managers often solely use surface water chemistry or water quality to address Clean Water Act (CWA) criteria or monitoring objectives. For ecosystems that have variable presence of surface water, like wetlands, this approach is problematic. For example, of 967 wetland sites included in the 2011 National Wetland Condition Assessment (NWCA), surface water chemistry was only obtainable at 537 sites, representing 41% of the wetland population area. Furthermore, the wetlands with surface water chemistry were disproportionally represented by wetland types with permanent sources of surface water. In this presentation, we introduce the concept of aquatic resource quality to meet CWA criteria and monitoring objectives. Aquatic resource quality is the ecological condition of an aquatic ecosystem. Evaluating aquatic resource quality requires the collective use of physical, chemical, and biological indicators to describe the ecological condition of the resource and identify factors negatively affecting condition. We present the wetland condition of the wetlands of the conterminous US based on the results of the 2011 NWCA generated using a biotic indicator (vegetation multimetric index). We also identify factors potentially affecting condition using ten physical, chemical, and biological indicators measured at each sampled site. We believe aquatic resource quality is a stronger measure of ecosystem integrity than water chemistry or water quality alone because (1) it can be consistently evaluated across all aquatic ecosystems, regardless of the presence of surface water, (2) it comprehensively addresses physical, chemical, and biological aspects of the ecosystem, and (3) it allows comparison and integration of information across aquatic ecosystem types. Moreover, the US Environmental Protection Agency's National Aquatic Resource Surveys have been collecting data for over a decade that provides a basis for aquatic resource quality in the continental US.

Citation

Kentula, M., A. Nahlik, Steve Paulsen, AND T. Magee. Wetland Assessment: Beyond the Traditional Water Quality Perspective. IntechOpen, London, UK92583, (2020). [DOI: 10.5772/intechopen.92583]

DOI: Wetland Assessment: Beyond the Traditional Water Quality Perspective