Connectivity of streams and wetlands to downstream waters: an integrated systems framework
Citation:
Leibowitz, S., P. Wigington, K. Schofield, L. Alexander, M. Vanderhoof, AND H. Golden. Connectivity of streams and wetlands to downstream waters: an integrated systems framework. JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION. American Water Resources Association, Middleburg, VA, 54(2):298-322, (2018). https://doi.org/10.1111/1752-1688.12631
Impact/Purpose:
Recent studies have focused on aquatic connectivity, or the degree to which aquatic ecosystems are connected and interact. Much of the interest in connectivity has arisen because of its relevance to past Supreme Court decisions identifying connectivity as a factor in determining the limit of EPA and the Army Corps of Engineers’ jurisdiction under the Clean Water Act. In 2015, an Office of Research and Development (ORD) report on connectivity of aquatic systems was released that reviewed and synthesized more than 1,300 peer-reviewed publications on this subject. That report provided much of the technical basis for the Clean Water Rule, which was subsequently stayed by the courts and which must be reviewed and rescinded or revised based on a recent Executive Order. This paper, which is derived from the ORD report and updated with recent additions to the literature, provides a framework to understand hydrological, chemical, and biological connectivity, focusing on how headwater streams and wetlands connect to and contribute to rivers. It also reviews methods to quantify hydrological and chemical connectivity. Streams and wetlands can influence downstream waters because of (1) their ability to alter material fluxes through source, sink, refuge, lag, and transformation functions, and (2) the presence of various transport mechanisms that connect these systems. Connectivity between these systems is not constant, but varies over space and time, and can be described in terms of frequency, duration, magnitude, timing, and rate of change. These characteristics are influenced by climate and the physical features of the watershed. Biological connectivity is also affected by species’ traits and behavioral responses to climate and the landscape. Human activities, such as dam construction and wetland drainage, affect connectivity, often in complex ways. The literature suggests that different analytical approaches and methods are necessary to quantify different types of connectivity across diverse environments, scales, and ecosystem functions. Information from this paper could allow regulators and aquatic managers to incorporate advances in the scientific understanding of connectivity into the process of identifying waters of national, state, or local importance. .
Description:
Interest in connectivity has increased in the aquatic sciences, partly because of its relevance to the Clean Water Act. This paper has two objectives: (1) Provide a framework to understand hydrological, chemical, and biological connectivity, focusing on how headwater streams and wetlands connect to and contribute to rivers. (2) Review methods to quantify hydrological and chemical connectivity. Streams and wetlands affect river structure and function by altering material and biological fluxes to the river, which depends on two factors: (1) functions within streams and wetlands that affect material fluxes, and (2) connectivity (or isolation) from streams and wetlands to rivers that allows (or prevents) material transport between systems. Connectivity can be described in terms of frequency, magnitude, duration, timing, and rate of change. It results from physical characteristics of a system, e.g., climate, soils, geology, topography, and the spatial distribution of aquatic components. Biological connectivity is also affected by traits and behavior of the biota. Connectivity can be altered by human impacts, often in complex ways. Because of variability in these factors, connectivity is not constant but varies over time and space. Connectivity can be quantified with field-based methods, modeling, and remote sensing. Further research is needed to classify and quantify connectivity of aquatic ecosystems and to understand how impacts affect aquatic connectivity.
URLs/Downloads:
DOI: Connectivity of streams and wetlands to downstream waters: an integrated systems framework