Chesapeake Bay Glossary


An egret at Blackwater National Wildlife Refuge.

Kevin Moore

Learn more in this glossary of terms related to the Chesapeake Bay.

A | B | C | D | E | F | H | M | N | P | R | S | T | W | Z

Abundance - a measure of how many of a species are available in a particular area

Algae - group of primitive, non-flowering plants which include certain seaweeds and microscopic phytoplankton

Anadromous fish - fish such as American shad that migrate from their primary habitat in the ocean to freshwater to spawn

Anaerobic - not containing oxygen or not requiring oxygen

Anoxic - a condition where no oxygen is present. Much of the "anoxic zone" is anaerobic, with absolutely no oxygen, a condition in which toxic hydrogen sulfide gas is emitted in the decomposition process

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Benthic organisms - plants and animals living in or on the bottom in aquatic habitats

Brackish water - mixture of fresh and salt water

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Catadromous fish - fish such as the American eel that migrate from their primary habitat in freshwater to the ocean to spawn

Continuous no-till - no-till agriculture practiced for multiple years (see no-till below)

Copepods - minute shrimp-like crustaceans; often they are the most common zooplankton in estuarine waters

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Decomposers - organisms (chiefly bacteria and fungi) that break down dead organic matter

Detritus - decomposed or partly decomposed plant and animal matter

Dissolved oxygen - microscopic bubbles of oxygen that are mixed in the water and occur between water molecules. Dissolved oxygen is necessary for healthy lakes, rivers, and estuaries. Most aquatic plants and animals need oxygen to survive. Fish will drown in water when the dissolved oxygen levels get too low. The absence of dissolved oxygen in water is a sign of possible pollution

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Ebb tide - falling or lowering tide

Ecological Reference Points - biological guidelines that account for a species' crucial role in the ecosystem

Ecology - the study of interrelationships of living things to one another and to their environment

Ecosystem - an interactive system of a biological community and its non-living environment

Erosion - the wearing away of land surface by wind or water; erosion occurs naturally but it is often intensified by man's land use practices

Estuary - semi-enclosed, tidal, coastal body of water open to the sea in which fresh and salt water mix

Eutrophication - the fertilization of surface waters by nutrients that were previously scarce. Eutrophication through nutrient and sediment inflow is a natural aging process by which warm shallow lakes evolve to dry land. Human activities are greatly accelerating the process. The most visible consequence is the proliferation of algae. The increased growth of algae and aquatic weeds can degrade water quality

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Flood tide - rising tide

Food chain - the sequence in which energy as food is transferred from one group of organisms to another

Food web - complex interaction of food chains in a biological community

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Habitat - the place where a plant or animal lives

Headwater - a tributary stream of a river close to or part of its source.

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Marsh - low, wet grassland without trees, periodically covered by water

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Nekton - free swimming aquatic organisms such as fish

Nitrogen - an inorganic nutrient essential for plant growth and reproduction when in oxidized forms (nitrate, nitrite, ammonia); excess can cause eutrophication; problems are usually associated with agricultural runoff and sewage

No-till - an agricultural practice that does not disturb the soil through tillage, leaving organic matter between crop rows, reducing erosion and runoff, preventing soil compaction, improving soil health, increasing water infiltration, and helping sequester carbon

Non-point source pollution - pollutants entering waterways from a general area such as runoff from farmland or suburban communities

Nutrients - chemicals (primarily nitrogen and phosphorous) necessary for organisms to live

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pH - a measure of the acidity or alkalinity of a material, liquid or solid; estuarine water is naturally, slightly base

strong acid - 0.0
neutral - 7.0
strong base - 14.0

battery acid - 0.2
orange juice - 4.2
blood - 7.5
Clorox bleach - 12.6

Phosphorous - an inorganic nutrient essential for plant growth and reproduction; excess can cause eutrophication; problems are usually associated with farmland runoff, sewage, and detergents

Phytoplankton - the plant form of plankton, most are microscopic; they are important as primary producers in an estuarine ecosystem

Photosynthesis - the process by which plants convert sunlight into living tissue using carbon dioxide, water, and nutrients; primary production

Plankton - passively drifting or weakly swimming organisms living suspended in the water column, often microscopic but sometimes visible to the naked eye

Point source pollution - pollution from a definable source, such as an outfall pipe

Pollution - the addition of a substance(s) to an environment in greater than natural concentrations as a result of human activity producing a net detrimental effect on the environment

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Recruitment - the number of new young fish in a population or the number of young fish that have attained a size for being legally caught

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Salinity - the measurement of the amount of dissolved salts in water, usually measured in parts per thousand; 35 ppt is average for seawater, 0 ppt for freshwater

Sediment - particles which accumulate on the bottom of a waterway

Sewage treatment -
primary = screening or settling large solids out of sewage (only removes visible material)
secondary = removal of organic material in sewage by aeration and bacterial action
tertiary = removal of nutrients and traces of toxic organic material from sewage by additional treatment processes

Submerged Aquatic Vegetation (SAV) - rooted vegetation which grows beneath the water surface

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Tides - periodic movement (raising and lowering) of a body of water by the gravitational attraction of the moon and sun with the rotation of the earth

Tributaries - streams and rivers that supply a larger body of water

Turbidity - the measurement of water cloudiness; it may be affected by sediment and plankton concentrations

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Watershed - an area of land that is drained by a river or other body of water

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Zooplankton - the animal form of plankton

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