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Submerged Aquatic Vegetation (Eelgrass)

Eelgrass and other SAV

Submerged aquatic vegetation (SAV) refers to rooted, vascular, flowering plants that, except for some flowering structures, live and grow below the water surface in coastal and estuarine waters in large meadows or small disjunct beds. SAV species of concern to CRMC for regulatory purposes include eelgrass (Zostera marina) and widgeon grass (Ruppia maritima).

SAV is integral to the health of shallow coastal areas. To other aquatic organisms they are an active part of the food cycle, a quiet nursery ground, or a place of attachment and refuge. The thin SAV leaves buffer wave action and collect suspended material to solidify the sediment below. Bay scallops, hard clams, tautog, starfish, snails, mussels, blue crabs, and lobster are just some of the species that depend on the eelgrass beds at some time during their lifecycle. Unfortunately, SAV habitats are often adversely affected by a number of anthropogenic activities: boat propellers; dredging and filling; fishing techniques such as scallop and clam dredging or toothed rakes; excessive habitat shading from docks or piers; and elevated nutrient levels that create algal blooms and high turbidity. Today SAV beds cover approximately 1300 of the 96,000 acres within Narragansett Bay.

Rhode Island’s primary SAV is eelgrass (Zostera marina). Eelgrass is a rooted, vascular, flowering plant that lives and grows below the water surface in coastal and estuarine waters in large meadows or small beds. Eelgrass plants are vital components of coastal ecosystems, providing food and shelter to numerous aquatic species, cycling nutrients from the water column and stabilizing marine sediments. As new growth replaces older eelgrass leaves, the dead leaves decay, becoming a valuable source of organic matter for microorganisms at the base of the food. Eelgrass reduces shoreline erosion caused by storms and wave energy thus protecting adjacent coastal properties. Eelgrass meadows can stabilize sediments and filter nutrients from the water column. Eelgrass also provides a unique habitat for recreational SCUBA divers and snorklers to explore.

SAV Resources

Web-based map of 2016 submerged aquatic vegetation in Narragansett Bay, RI Coastal Ponds and Block Island

Web-based map of 2012 submerged aquatic vegetation in Narragansett Bay and RI Coastal Ponds

Current and historical eelgrass data on the RI Geographical Information System website

Reports from the RI Eelgrass Mapping Task Force

SAV Regulations

The goal of CRMC is to preserve, protect, and where possible, restore SAV habitat. The following activities under CRMC jurisdiction are required to avoid and minimize impacts to SAV habitat under Section 300.18 of the RI Coastal Resources Management Program (RICRMP):

For a complete listing and explanation of regulations that may pertain to your permit application, please see the RICRMP and/or contact CRMC staff at 401/783-3370.

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