Assessing the Effects of Shoreline Erosion
Shoreline erosion is a major concern in coastal regions on both coasts of North America. Landowners, both private and public, in the mid-Atlantic region in particular, have experienced real estate losses as sea levels rise and land masses subside, thereby increasing rates of erosion. To counter this threat, many landowners have implemented shoreline stabilization projects, typically involving breakwaters or revetments in order to curb erosion. While a large body of work has been conducted by governments, academia, community groups and other non-governmental organizations towards habitat restoration, much of it has been done without firm plans for monitoring the impacts of the work. Reporting of impacts of restoration projects has largely focused on quantitative metrics of area created (e.g. acres of salt marsh, number of oysters, etc). However, our understanding of how these created habitats function ecologically is still in its infancy.
To improve upon the understanding of the effects of shoreline modification, scientists at Ecosystem Solutions are assessing various ecosystem processes (vegetation, fish and invertebrate communities) at several locations throughout the Chesapeake Bay: Naval Air Station Patuxent River, Aberdeen Proving Ground, and Langley Air Force Base. These installations have completed, or are in the planning process of implementing various types of shoreline modification projects, including revetments, stone breakwaters, and low sills in a diversity in salinity regimes. These projects will undoubtedly have an effect on the nearshore aquatic community structure. Impacts to submerged vegetation (or SAV), fish, and benthic invertebrates are perhaps the likeliest and of most interest to natural resource managers. To determine changes in the environment, scientists will establish biological reference points, assessments of ecosystem function, and comparisons to "natural" systems. Below is a list of activities that we are carrying out to more clearly understand the effects of modification in shallow water estuarine systems.
Fish Community Structure Surveys
Scientists are carrying out seasonal (here defined as spring, early summer, late summer, and autumn) assessments that include sampling for both demersal (using trawl) and littoral (using seine) fish species. Sites are selected using controls (no impact) and impacted regions, creating a (B)efore, (A)fter, (C)ontrol, and (I)mpact design. We will continue this approach for multiple years in order to quantify variability in assemblage structure that may be attributable to annual fluxuations. Additional data that will be collected includes tidal state and water quality metrics (salinity, temperature, dissolved oxygen) that are known to influence fish assemblage structures (Murphy and Secor 2005).
Benthic Invertebrate Community Structure Surveys
In addition to the fish fauna, we will also examine the community structure of the benthic invertebrate populations that reside in/on the sediments of the shallow water area adjacent to the impacts. These sites will be the same as the nearshore fish sites and sampling occurs at the same seasonal scale of the fish survey. Samples are sorted and organisms identified to species level (where appropriate) and ecological metrics (diversity, trophic level, feeding guild) will be developed.