20 Jul 2022

Scenario Analyses in Ecological Modeling and Ecosystem Management

Purpose: Ecosystem management and restoration practitioners are challenged with complex problems, diverse project goals, multiple management alternatives, and potential future scenarios that change the systems of interest. Scenario analysis aids in forecasting, evaluating, and communicating outcomes of potential management actions under different plausible conditions, such as land-use change or sea level rise. However, little guidance exists for practitioners on the utility and execution of scenario analysis. Therefore, this technical note highlights the usefulness of scenario analysis as a tool for addressing uncertainty in potential project outcomes. The mechanics of the scenario-analysis process are explained, and examples of different types of scenario analyses are described for context on the breadth of its use. Lastly, two hypothetical case studies of scenario analysis in ecological modeling are presented showing a semiquantitative approach for assessing anadromous fish and a quantitative approach examining freshwater mussel habitat. Overall, this technical note provides a brief review of the utility and application of scenario analyses in the context of ecological modeling and ecosystem management decision-making.

8 Jul 2022

Techniques for Developing Bars and Islands in Incising Channels

Abstract: Sandbars and islands provide important nesting and foraging habitat for birds (including listed species) and shallow water habitat for many aquatic species in riverine ecosystems. In-stream habitat is especially important in incised channels lacking floodplain connectivity, with channel bars providing important riparian habitat. However, some river management practices significantly alter and sometime eventually eliminate these important habitats. Several US Army Corps of Engineers districts are planning or actively building instream bars and islands using flow management and/or instream structures. Sister agencies (e.g., US Bureau of Reclamation) have similar initiatives downstream of their reservoir structures. This report outlines considerations for establishing and managing sandbar and island features. It presents a compilation of proven techniques for promoting sandbar and island development and for reducing erosion of these features.

1 Oct 2021

Environmental Factors Affecting Coastal and Estuarine Submerged Aquatic Vegetation (SAV)

Abstract: Submerged aquatic vegetation (SAV) growing in estuarine and coastal marine systems provides crucial ecosystem functions ranging from sediment stabilization to habitat and food for specific species. SAV systems, however, are sensitive to a number of environmental factors, both anthropogenic and natural. The most common limiting factors are light limitation, water quality, and salinity, as reported widely across the literature. These factors are controlled by a number of complex processes, however, varying greatly between systems and SAV populations. This report seeks to conduct an exhaustive examination of factors influencing estuarine and coastal marine SAV habitats and find the common threads that tie these ecosystems together. Studies relating SAV habitats in the United States to a variety of factors are reviewed here, including geomorphological and bathymetric characteristics, sediment dynamics, sedimentological characteristics, and water quality, as well as hydrologic regime and weather. Tools and methods used to assess each of these important factors are also reviewed. A better understanding of fundamental environmental factors that control SAV growth will provide crucial information for coastal restoration and engineering project planning in areas populated by SAVs.