Document Type



Virginia Institute of Marine Science

Publication Date



Beds of submerged aquatic vegetation (SAV) are important natural resources which are critical habitats for life stages of many commercially and recreationally important species of fish, crabs and shellfish in Virginia. SAV is comprised of rooted flowering plants which have historically grown throughout the Chesapeake Bay and Eastern Shore coastal lagoons in subtidal areas where water depths are less than 6 feet (Orth and Moore 1983). The presence of SAV in an area is indicative of water quality conditions which are low in nutrient enrichment and turbidity (Dennison et al. 1993). Given this relationship between water quality and growth, SAV have been chosen as an indicator species with which improvements in water quality conditions in the Chesapeake Bay and coastal lagoon systems are assessed (Chesapeake Bay Executive Council, 1992).

SAV nearly disappeared from Virginia's coastal lagoons and lower Chesapeake Bay regions in the 1930's attributable in part to an infestation of disease. Subsequent re-growth in the lower bay was reversed in the 1970's as decades long deteriorations in water quality, combined with large inputs of sediments and nutrients from Tropical Storm Agnes reduced SAV to only 10% of their historic abundance (Orth and Moore 1984). In Virginia's coastal lagoons only Chincoteague Bay has experienced any subsequent recovery. Figure 1 shows the recent regrowth of SAV in Chincoteague and other northern coastal bays over the past 11 years as determined from annual aerial surveys. Each year the distribution and abundance of SAV in the Chesapeake Bay and Virginia's coastal lagoons are mapped by VIMS scientists from aerial photography which is flown specifically for that purpose (Orth et al. 1996). Although a principal objective is to monitor area wide changes in SAV abundance, the photography is of such a scale and quality that impacts to SAV from dredging operation or boat scars are readily apparent (see accompanying photographs). Beginning in 1995 a few circular dredge scars were observed in SAV beds in the Virginia portion of Chincoteague Bay. These scars appeared to increase in number and size in 1996 and 1997, prompting us to alert officials at VMRC as to the increasingly significant impacts to the only remaining SAV populations along Virginia's Eastern Shore.

The objective of this report is to provide a summary of the field and laboratory analyses of impacts of the dredge scars to SAV in Chincoteague Bay, Va. for the Commission.


Report to The Virginia Marine Resources Commission



Seagrasses -- Effect of dredging on -- Virginia., Seagrasses -- Effect of dredging on -- Chincoteague Bay (Md. and Va.), Clam fisheries -- Environmental aspects -- Virginia.



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