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Submerged aquatic vegetation (SAV) abundance and diversity in the tidal Potomac River and estuary

Submerged aquatic vegetation (SAV) abundance and diversity in the tidal Potomac River and estuary By Nancy Rybicki, Jurate Landwehr, Edward Schenk, and Julie Baldizar

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Submerged aquatic vegetation (SAV) abundance and diversity in the tidal Potomac River and estuary

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  1. Submerged aquatic vegetation (SAV) abundance and diversity in the tidal Potomac River and estuary By Nancy Rybicki, Jurate Landwehr, Edward Schenk, and Julie Baldizar Goal: provide managers with information to help them understand variation in SAV coverage and determine strategies to meet the SAV restoration goal.

  2. Variation in SAV coverage, Potomac River SAV data from http://www.vims.edu/bio/sav : No data

  3. Solar radiation Water clarity is the primary factors influencing SAV abundance. Literature review and analyses indicated MLRs of 13% light for the fresh and oligohaline and 22% for mesohaline to polyhaline SAV community (Carter et al. 2000, Batiuk et al. 2000, Kemp, et al. 2004) Light Water Temperature Wind Speed Phyto- plankton Total Suspended Solids Nutrients River Flow Epiphytes Secchi depth of 0.7m = 13% light at 1m Submersed Aquatic Vegetation

  4. 1) EVALUATION OF SUBMERGED AQUATIC VEGETATION (SAV) AND WATERFOWL POPULATIONS WITH RESPECT TO EXOTIC SPECIES AND IMPROVING WATER QUALITY 2) POSSIBLE CAUSE OF VIRGINIA TRANSPLANTS 2003 & 2004 3) MAP SHOWING POTENTIAL AND CONTINUEING USGS WORK

  5. Improved water quality in an estuary with exotics enhances SAV diversity and waterfowl habitat, by Rybicki and Landwehr Study Area Data source: SAV species, USGS and DC gov’t SAV coverage, VIMS Water quality, MDDNR Waterfowl, Audobon Christmas bird count

  6. SAV productivity is density specific SAV coverage, in hectares Rybicki and Landwehr, in process

  7. Conclusions 1985-2001 Potomac River- Productivity of native, as well as exotic, SAV species was shown to vary with factors affecting water column light attenuation (TSS, Chlorophyll a). Winter waterfowl increased significantly with SAV coverage, despite dominance by exotics. SAV productivity was largely driven by Hydrilla productivity 1985-2001 Previous years propagules (tubers, seeds, etc) may dampen the effect of environmental variation Our findings support management strategies to improve water clarity and reduce nutrient concentration in order to protect diversity and waterfowl habitat

  8. Exploring Causes of a Seagrass Transplant Failure in the Potomac River (Virginia) –Mitigation for loss of SAV at Wilson Bridge construction site We monitored a seagrass transplant site (Judith Sound) and a reference site (Dameron Marsh), in VA. The transplant site was one of six SAV transplant sites in the Potomac that have only been marginally successful since transplanting began in 2000 (written communication, Justin Reel). March to November, of 2003 and 2004, at both sites we measured habitat variables monthly, including sedimentation and erosion, shoot length and burial, salinity, and light attenuation. Natural eelgrass at reference site and eelgrass tranplanted in fall 02 and fall 03 (written communication, Justin Reel) did poorly in 2003 and 2004

  9. Exploring Causes of a Seagrass Transplant Failure in the Potomac River (Virginia) –Mitigation for loss of SAV at Wilson Bridge construction site Figure 1. Precipitation and salinity during 2003 and 2004 at the transplant site and reference site. Precipitation data from Norfolk International Airport

  10. Exploring Causes of a Seagrass Transplant Failure in the Potomac River (Virginia) –Mitigation for loss of SAV at Wilson Bridge construction site • Both sites were above the median 22 percent light level • The percent of shoot that was buried was greater at the transplant site (22 percent) than at the reference site (11 percent), although both percentages were below levels shown to be detrimental to eelgrass survival (Veermaat and others 1997). • Monitoring data support the conclusion that salinity not erosion or accretion, were the primary factors responsible for the decline of eelgrass at both sites. • Low sediment fertility may also play a role in lack of success at the eelgrass transplant site.

  11. Potomac integrative analysis will enhance USGS SAV studies and other potentialstudies to explain ecosystem change to help assess the effectiveness of restoration strategies 2003 SAV Maryland Tracking sediment sources using isotopic tracers (Allen Gellis, USGS) Wetland restoration and sediment accretion studies Relationship between environmental variables and species of SAV Field investigations of SAV health, sediment characteristics, water quality, and maximum depth of SAV, w/ many cooperators Dameron Marsh natural SAV health as a reference site for SAV transplants Image from MDDNR website

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