• Aquatic reef

    A solid, three-dimensional ecological community made up of densely packed oysters or other artificial substances. Aquatic, or oyster, reefs provide vital habitat for finfish, crabs and other invertebrates.

  • Bivalve

    An aquatic mollusk whose compressed body is enclosed within a hinged shell. For example, clams, oysters and mussels are bivalves.

  • Chemical contaminants

    Pesticides, pharmaceuticals, metals and other toxic substances that can harm the health of both humans and wildlife.

  • Dermo

    An oyster disease caused by the protozoan parasite Perkinsus marinus, which many Chesapeake Bay oysters contract in their second year of life.

  • Ecosystem

    A natural unit formed by the interaction of a community of plants and animals with the environment in which they live. All of the elements of an ecosystem interact with each other in some way, depending on each other directly or indirectly.

  • Filter feeder

    An organism that feeds by straining plankton and other food particles from water that is pumped through its gills or mouth. For example, oysters and menhaden are filter feeders.

  • MSX

    A parasitic oyster disease that thrives in warm, high-salinity waters and can affect oysters of all ages.

  • Sediment

    Loose particles of sand, silt and clay that settle on the bottom of rivers, lakes, estuaries and oceans. Suspended sediment pushed into the water by erosion is one of the biggest impairments to water quality in the Chesapeake Bay.

  • Sedimentation

    The accumulation of sediment in an area, filling shipping channels and covering oysters and other bottom-dwelling organisms. Sedimentation is also called siltation.

  • Spat

    Juvenile oysters that have just attached to a hard surface.

  • Tributary

    A creek, stream or river that flows into a larger body of water. For example, the Susquehanna, Potomac and James rivers are tributaries of the Chesapeake Bay.

  • Year class

    All of the fish of any species that hatched during one annual spawning period.

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