Ecological Research on Wetlands and Submersed Aquatic Vegetation

Submersed aquatic vegetation investigations in Chesapeake Bay
    Bibliography of USGS investigations in Chesapeake Bay
    Timeline of important events in the history of SAV and Trapa natans in the Potomac River
    Related links to submersed aquatic vegetation and Chesapeake Bay information

Wetland importance
    Project description and publications
   Vegetative resistance to flow investigations in the Florida Everglades
    Links to South Florida ecosystem information

Water, energy, and biogeochemical budget (WEBB) and the interdisciplinary research initiative (IRI)

Submersed Aquatic Vegetation (SAV) photographs (click for larger images)

Boat reflection and Stargrass (Heteranthera) with milfoil (Myriophyllum)	Stargrass (Heteranthera) with milfoil (Myriophyllum)	Wild celery (Vallisneria) and its white flower and its pollen on surface	Wild celery (Vallisneria) and its white flower and its pollen on surface with some milfoil (Myriophyllum)	Mixed SAV in Potomac River, 2007
Credit: Nancy Rybicki, U.S. Geological Survey	Credit: Nancy Rybicki, U.S. Geological Survey	Credit: Nancy Rybicki, U.S. Geological Survey	Credit: Nancy Rybicki, U.S. Geological Survey	Credit: Curtis Dalpra, Interstate Commission on the Potomac River Basin

 The U. S. Geological Survey (USGS) began a comprehensive interdisciplinary study of the tidal Potomac River and Estuary in Maryland, Virginia, and the District of Columbia in 1977. The overall goal was to understand the major aspects of hydrodynamic, chemical, and biological processes and their interactions in a tidal river-estuarine system (Callendar et al, 1984, bibliography Potomac Estuary Study). As part of that study, this project has been involved in studies to determine factors affecting the distribution and abundance of submersed aquatic vegetation (SAV) and the effect of SAV on water quality and flow. Starting in 1978, USGS personnel have monitored the distribution of SAV in the freshwater tidal Potomac River. USGS, in collaboration with the Fisheries division of the DC Department of Health, conducts a shoreline survey of the tidal Potomac River as far south as Maryland Point, estimating coverage of SAV and percent cover by species (Ruhl et al. 1999, Rybicki et al. 2007, 2008). Information on species distribution and SAV density are supplied to the Virginia Institute of Marine Science (VIMS) to complement the annual bay-wide survey of SAV and/or the Metropolitan Washington Council of Governments (COG) to help in their aquatic plant control program. The monitoring data have been used in many of the reports in the project bibliography.

The project has conducted research on factors affecting the distribution and abundance of SAV in the freshwater tidal Potomac River and the oligohaline Potomac River Estuary in order to supply information relevant to the restoration of SAV. USGS cooperated with VIMS, the Environmental Protection Agency, the University of Maryland, and Harford Community College to develop SAV Habitat Requirements and Restoration Targets (Batiuk et al. 1992, Batiuk et al. 2000). Input to the technical synthesis document consisted of results of prior research on the factors affecting distribution and abundance of SAV and analysis of water-quality data gathered by the USGS and by the states of Maryland and Virginia and the District of Columbia. USGS made a detailed analysis of water-quality and weather data for the tidal Potomac River between 1980 and 1989 (Carter et al. 1994). As suggested in an earlier publication (Carter and Rybicki 1990), they determined that available light was the primary factor controlling distribution in the tidal river, but, in addition, weather played an important role. Over time, reduced nutrients and suspended sediments have increased the abundance and diversity of SAV in the Potomac (Rybicki and Landwehr, 2007; Ruhl and Rybicki, 2010. More than a dozen species of SAV now co-exist in this reach of the Potomac that was almost barren in a 1978-1981 USGS study. Our results suggest that widespread recovery of SAV and diversity can be achievable if restoration efforts are enhanced across the Bay.

The U. S. Geological Survey also conducted field experiments that demonstrated that beds of SAV were capable of altering the ambient water quality in the tidal river, increasing oxygen and pH during the daylight hours and maintaining clear water with low total suspended sediment and chlorophyll a in the beds (Carter et al. 1991). Field studies also showed that dense beds of submersed macrophytes altered flow velocity and could cause water levels to rise and fall more slowly in the bed than in the channel. This sets up a water-level gradient between the bed and the channel (Rybicki et al. 1997). This gradient causes flow in the bed. The Wetlands/SAV research team investigates a broad range of ecological topics in Chesapeake Bay, its tributaries, and in Florida Everglades.