Assessing Submerged Aquatic Vegetation Restoration in Chesapeake Bay
Submerged aquatic vegetation (SAV) is a highly important component of the Chesapeake Bay ecosystem. SAV beds serve critically important habitat- and water quality-related functions, including serving as refuge and nursery areas for juvenile fish and crustaceans. Healthy SAV beds also improve local water quality by absorbing excess nutrients from the water column and sediments, promoting the settling of suspended sediments, stabilizing the substrate, oxygenating the water via photosynthesis, and absorbing heavy metals and other anthropogenic contaminants from the substrate via roots and rhizomes. Additionally, robust SAV beds can buffer the local shoreline by reducing wave energy, thereby minimizing shoreline erosion. In addition, several Chesapeake Bay SAV species are an important food source to native and migrant waterfowl species, including many on the Federal Endangered and Protected lists.
Because of the documented habitat functions of SAV beds and the respective need for sufficient water quality, natural resource managers, watermen, and scientists look to SAV as a primary bio-indicator of the overall health of the Chesapeake Bay, likening it to “a canary in a coal mine”. Consequently, numerous Federal, State, and local agencies and organizations have implemented programs aimed at better understanding the natural fluctuations, water quality requirements, and applicable restoration techniques of SAV populations in the Chesapeake Bay. Between 1997 and 2005, the Department of Defense identified over 10 sites as potentially able
to support SAV due to adequate water quality conditions. A series of test plots (defined as
< 1000 plants) were initially planted, followed by a large-scale restoration effort (> 2500 plants). The immediate success of these plantings was often positive, with observed short-term survivability. Other plantings did not fare as well, but did flower and produce seeds before disappearing altogether. Since monitoring resources were often minimal, and monitoring visits sparse, the long-term success of these efforts remains largely undocumented. This project is providing much-needed monitoring for DoD SAV restoration plots established over the past ten years, as well as data that aides in interpreting restoration success/failure and in the selection of new sites (or expanding previous ones) for more comprehensive large-scale restoration. In addition, researchers carried out an on-site training and lessons learned workshop where natural resource managers from installations across the bay identified SAV species, learned how to identify the best sites for potential restoration, and how to best to ensure success at their next SAV restoration site.
Water Quality
At each site visit, researchers used a Yellow Springs Instrument (YSI) to take water quality measurements. Measurements included dissolved oxygen, temperature, conductivity and salinity. To accomplish this, personnel submerged the YSI probe to approximately mid-column, allowed measurements to calibrate, and took readings. All data was recorded in Excel spreadsheets, and is undergoing statistical analysis. Check back over the next few months to see their results.
SAV Stem Counts
To determine the success of the restoration, personnel carried out SAV stem counts at randomly chosen areas within the restored bed. To do this, they used a 1 meter x 1 meter square grid tossed within the SAV bed. Once submerged, researchers used SCUBA gear to lie on the bottom and count each individual plant within the grid. Numbers were recorded on underwater slates, and transferred to an EXCEL database. Check back over the next few months to see their results.
SAV Workshop
Personnel from Ecosystem Solutions the Chesapeake Research Consortium, and the Army Environmental Center carried out a two day SAV Restoration and Ecology training workshop. The workshop was hosted by Naval Facilities Command Mid-Atlantic, and held at Naval Amphibious Base Little Creek, on October 27/28, 2007. Those who attended the workshop sat in on sessions ranging from DoD's commitment to Chesapeake Bay restoration activities, the important role of SAV in estuaries, different approaches to monitoring SAV restoration success, water quality monitoring basics and a case study for SAV restoration, and training in SAV species identification and water quality monitoring. As part of the workshop, all attendees received a copy of "Underwater Grasses in the Chesapeake Bay and Mid-Atlantic Coastal Waters - Guide to Identifying Submerged Aquatic Vegetation," published in 2006 by Maryland Sea Grant, and authored by this project's co-Principle Investigators.