Bay (Critter) Profile: Eelgrass

Eelgrass plays a remarkable role in the estuarine food web through its ability to stabilize benthic habitats, provide protection and shelter, and supply food. Common Eelgrass (zostera marina) is actually a grass-like flowering plant, having migrated into the sea in comparatively recent geologic history, and has brilliant green, long, slender tendrils that wave to and fro with the water current. Eelgrass prefers shallow inter-tidal waters with abundant sunlight, where it averages a foot tall.

Eelgrass, through its root system, stabilizes sandy bottomlands while it filtrates and absorbs nutrients, preventing the suppression of oxygen from nutrient loading. Through the plant’s waving motion, it also lessens the impact of tides and waves on the shorelines. The result is stable habitats in inter-tidal zones that provide important protection and shelter to immature fish and invertebrates. In fact, the decline in the bay scallop population is closely correlated to the disappearance of eelgrass.

Not only does eelgrass create a community, but it acts as a food source. Although black ducks and other waterfowl depend on eelgrass as their main diet, the main role of eelgrass in the food web is detritus or the decay of plant material. The detritus becomes coated in bacteria and fungi and, through an enzymatic process, the eelgrass particle diminishes in size over time, making it available to a wide range of different consumers throughout the food chain.

Throughout the entire Northeast in the early ‘30s, eelgrass meadows, due to a slight rise in temperature, were wholly decimated by the wasting disease, leading to the disappearance of waterfowl and marine life and also contributing to the erosion of beaches and shorelines. Eelgrass was again devastated by the brown tides over the last two decades. Although eelgrass is beginning to recuperate, it continues to be threatened by threats to water quality from pollution, dredging and shoreline hardening. The reestablishment of eelgrass meadows is fundamental for the ecologically and economically important revitalization of the fish and shellfish populations and the sustainability of the estuaries.