Historic and Present-Day Environmental Issues Involving Tomato Plasticulture and Shellfish Aquaculture on Virginia’s Eastern Shore
The Eastern Shore of Virginia, located on the Delmarva Peninsula, is known for its agricultural commodities, especially Solanum lycopersicum, Crassostrea Virginia, and Mercenaria mercenaria. For decades, controversy has surrounded the two industries. Runoff from fields of tomatoes grown in plastic mulch was thought to have caused mass casualties of shellfish in hatcheries in the tidal creeks and bays of the Eastern Shore. The impervious surface of the plastic mulch decreases infiltration of rainfall and increases runoff velocity and volume. Several studies have sought to determine the effect of plasticulture systems on water quality, which in turn affects aquaculture production. Many chemicals, including pesticides and copper, are applied to tomatoes grown in a plasticulture system to reduce disease, weed, and pest pressure. When applied after plastic mulch has been laid, these chemicals can wash off of the plants and the plastic mulch during a rain event. Unfortunately, studies have shown that copper, as well as other chemicals used in tomato production, have a detrimental effect on shellfish growth and survival. Increased amounts of sediment in runoff waters due to erosion of fields also have negative effects on shellfish production. After the threat of regulation in the late 1990s, the tomato industry on the Eastern Shore has been working closely with several agencies to implement best management practices (BMPs) for the reduction of erosion and runoff. These conservation practices have been proven effective in reducing impacts on water quality. Water quality monitoring should be continued to determine whether the implementation of these BMPs is indeed decreasing tomato production’s negative impact on the aquaculture industry on the Eastern Shore of Virginia.