Glossary of Chesapeake Bay Terms

| A | B | C | D | E | F | G H I | J K L | M | N | O | P Q | R | S | T U V | W | X Y Z |

A

Acid rain - Natural rainfall which contains nitric and sulfuric acids due to oxides of nitrogen and sulfur dioxide discharged into the air by industries, power plants, and automobiles.

Anadromous - Fish that spend most of their life in salt water but migrate into freshwater tributaries to spawn (i.e. shad, sturgeon).

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.

Anthropogenic - Of human origin.

Aquatic - Living in water.

Artificial reef - A structure aggregated from material designed to attract living aquatic organisms (i.e. oyster reef)

Atmospheric deposition - When the air pollution hits the earth surface. Air pollution washed out of the sky by rain or snow is called "wet deposition." When air pollution deposits without benefit of rain its called "dry deposition."

Autotroph - Any organism that is able to manufacture its own food. Most plants are autotrophs, as are many protists and bacteria. Autotrophs may be photoautotrophic, using light energy to manufacture food, or chemoautotrophic, using chemical energy.

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B

Baseflow - Stream or river flows consisting entirely of groundwater contributions.

Benthos - A group of organisms, most often invertebrates, that live in or on the bottom in aquatic habitats (such as clams that live in the sediments) which are typically immotile or of limited motility or range.

Best Management Practices (BMP) - A practice or combination of practices that provide the most effective and practicable means of controlling point and nonpoint pollutants at levels compatible with environmental quality goals.

Biological Nutrient Removal (BNR) - A temperature dependent process in which the ammonia nitrogen present in raw wastewater is converted by bacteria first to nitrate nitrogen and then to nitrogen gas.

Biomass - The quantity of living matter, expressed as a concentration or weight per unit area.

Bivalve - Mollusk with two shells connected by a hinge (i.e. clams, oysters).

Bloom - A population burst of phytoplankton that remains ithin a defined part of the water column

Bog - A wetland that has poorly drained acidic peat-soil dominated by sedges and sphagnum moss.

Brackish - Somewhat salty water, as in an estuary.

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C

Carapace - A bony or chitenous case or shell covering the back or part of the back of an animal, such as a crab.

Carnivore - Literally, an organism that eats meat. Most carnivores are animals, but a few fungi, plants, and protists are as well.

Catadromous - Fish that live in freshwater and migrate to saltwater to spawn (i.e. American eel).

Class - Subdivision of a phylum containing a group of related orders.

Coastal plain - The level land with generally finer and fertile soils downstream of the piedmont and fall line, where tidal influence is felt in the rivers.

Commensal - Having benefit for one member of a two-species association but neither positive nor negative effect on the other.

Consumer - Any organism which must consume other organisms (living or dead) to satisfy its energy needs.

Crustaceans - The class of aquatic Arthropods including copepods, isopods, amphipods, barnacles, shrimp, and crabs which are characterized by having jointed appendage and gills.

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D

Denitrification - The conversion of nitrite and nitrate nitrogen (after nitrification) to inert nitrogen gas. This treatment process requires that little or no oxygen be present in the system and that an organic food source be provided to foster growth of another type of bacteria. The organic food source can be either recycled waste activated sludge or methanol. The resultant nitrogen gas is released to the atmosphere.

Detritus - Accumulated organic debris from dead organisms, often an important source of nutrients in a food web.

Detrivore - Any organism which obtains most of its nutrients from the detritus in an ecosystem.

Diatoms - Tiny, single-celled or colonial algae with skeletons made of silica that either drift with the motion of the water or are attached to surfaces.

Dinoflagellate - Algae of the order Dinoflagellata.

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.

Diurnal - Active during daylight.

Diversity - An ecological measure of the variety of organisms present in a habitat.

Dry Deposition - Atmospheric deposition that occurs when particles settle to a surface, collide with and attach to a surface (adsorption) or are absorbed.

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E

Ebb tide - A falling tide.

Ecology - The study of interrelationships between living things and to their environment 

Ecosystem - All the organisms in a particular region and the environment in which they live. The elements of an ecosystem interact with each other in some way, and so depend on each other either directly or indirectly.

Effluent - The discharge to a body of water from a defined source, generally consisting of a mixture of waste and water from industrial or municipal facilities.

Emergent Wetland - A wetland dominated by nonwoody, soft-stemmed plants.

Emissions - Refers to pollution being released or discharged into the air from natural or man-made sources. Pollutants may be released directly into the air from a structural device (i.e., smokestack, chimney, exhaust pipe) or indirectly via volatilization or dispersal (i.e., aerosol spraying).

Endemic species - A species that is restricted in its distribution to a particular locality or region.

Environment - The place in which an organism lives, and the circumstances under which it lives. Environment includes measures like moisture and temperature, as much as it refers to the actual physical place where an organism is found.

Epifaunal - Plants, animals and bacteria that are attached to the hard bottom or substrate (for example, to rocks or debris); are capable of movement; or that live on the sediment surface.

Epiphyte - A plant which grows upon another plant. The epiphyte does not "eat" the plant on which it grows, but merely uses the plant for structural support, or as a way to get off the ground and into the canopy environment.

Erosion - The disruption and movement of soil particles by wind, water, or ice, either occuring naturally or as a result of land use.

Estuarine species - A permanent resident of an estuary. Also called a resident species.

Estuary - A semienclosed body of water that has a free connection with the open sea and within which seawater (from the ocean) is diluted measurably with freshwater that is derived from land drainage (i.e. the Chesapeake Bay). Brackish estuarine waters are decreasingly salty in the upstream direction and vice versa. The ocean tides are projected upstream to the fall lines.

Exotic Species - Any introduced plant or animal species that is not native to the area and that may be considered a nuisance.

Extant species - A species which is currently in existence (the opposite of extinct).

Extinct species - A species which has disappeared from existence due to either natural or human-induced means (opposite of extant).

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F

Fall Line - A line joining the waterfalls on several rivers that marks the point where each river descends from the upland to the lowland and marks the limit of navigability of each river.

Fecundity - The number of eggs produced per female per unit time (often: per spawning season)

Filter feeder - An organism which filters food from the environment via a straining mechanism (such as gills)(i.e. barnacle)

Flood tide - A rising tide.

Food chain / food web - The network of feeding relationships in a community as a series of links of trophic levels, such as primary producers, herbivores, and primary carnivores. Includes all interactions of predator and prey, along with the exchange of nutrients into and out of the soil. These interactions connect the various members of an ecosystem, and describe how energy passes from one organism to another.

Freshet - An increase of water flow into an estuary during the late winter or spring, owing to increased precipitation and snow melt in the watershed.

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GHI

Habitat - The place and conditions in which an organism lives.

Herbivore - Literally, an organism that eats plants or other autotrophic organisms. The term is used primarily to describe animals.

Hypoxic - A condition where only very low levels of oxygen are present.

Indigenous Species - A species which evolved on the North American continent, was present at the time of European Colonization, and is resident within the Chesapeake Bay basin without human manipulation.

Intertidal - The area of shore located between high and low tides.

Introduced Species - Species which have been intentionally or inadventently brought into a region or area. Also called exotic species.

Invertebrate - Animals which lack a backbone and include such as squids, octopuses, lobsters, or shrimps, crabs, shellfishes, sea urchins and starfishes.

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JKL

Juvenile - Strictly speaking, a juvenile is any of a species which is not yet sexually mature. In the context of many surveys, however, it is most often used interchangeably with young-of-year (YOY).

Keystone species - A predator at the top of a food web, or discrete subweb, capable of consuming organisms of more than one trophic level beneath it.

Larva - A discrete stage in many species, beginning with zygote formation and ending with metamorphosis.

Littoral zone - The intertidal area, also known as the splash zone.

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M

Macro-organism - An organism visible without the aid of a microscope.

Macrophyte - An individual alga large enough to be seen easily with the unaided eye.

Macroplankton - Planktonic organisms that are 200-2,000 micrometers in size.

Mammal - Any of a large class called Mammalia; warm blooded, usually hairy vertebrates whose offspring are fed with milk secreted by the mammary gland.

Marine - Refers to the ocean.

Marsh - An emergent wetland that is usually seasonally flooded or wet, and often dominated by one or a few plant species.

Mesohaline - Pertaining to moderately brackish water with low range salinities (from 5-18 parts per thousand)

Micro-organism - An organism requiring magnification to see/study (microscopic).

Micron - A unit of measure equal to one thousandth of a millimeter

Migratory - Describing groups of organisms which move from one habitat to another on a regular or seasonal basis.

Mollusk - The invertebrate phylum which contains bivalves (i.e. oysters), gastropods (i.e. snails), and squids.

Molt - To shed the exoskeleton (outer covering)or prior to new growth (i.e. blue crab).

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N

Native Species - Species which have lived in a particular region or area for an extended period of time.

Nekton - Organisms with swimming abilities that permit them to move actively through the water column and to move against currents (i.e. fish, crabs).

Neritic - A part of the pelagic zone which extends from the high tide line to the bottom.

Niche - A general term referring to the range of environmental space occupied by a species

Nitrogen - (N) is used primarily by plants and animals to synthesize protein. Nitrogen enters the ecosystem in several chemical forms and also occurs in other dissolved or particulate forms, such as tissues of living and dead organisms.

Nocturnal - Active only at night.

Nonpoint Source - A diffuse source of pollution that cannot be attributed to a clearly identifiable, specific physical location or a defined discharge channel.

Nutrients - Compounds of nitrogen and phosphorus dissolved in water which are essential to both plants and animals. Too much nitrogen and phosphorus act as pollutants and can lead to unwanted consequences - primarily algae blooms that cloud the water and rob it of oxygen critical to most forms of aquatic life. Sewage treatment plants, industries, vehicle exhaust, acid rain, and runoff from agricultural, residential and urban areas are sources of nutrients entering the Bay.

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O

Oligohaline - Pertaining to moderately brackish water with low range salinities (from .5-5 parts per thousand)

Oligotrophic - Refers to water bodies or habitats with low concentrations of nutrients.

Omnivore - Literally, an organism that will eat anything. Refers to animals who do not restrict their diet to just plants or other animals.

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PQ

Parasite - A plant or animal which lives on or in an organism of another species from which it derives its nutrition and/or protection; usually without benefit to the host and often with harmful effects.

Pelagic - The open ocean, excluding the ocean bottom and shore.

pH - Measure of the acidity or basicity of water (-log10 of the activity of hydrogen ions in water).

Phosphorus - (P) A key nutrient in the Bay's ecosystem, phosphorus occurs in dissolved organic and inorganic forms, often attached to particles of sediment. This nutrient is essential to cellular growth and reproduction for organisms such as phytoplankton and bacteria. Phosphates, the inorganic form are preferred, but organisms will use other forms of phosphorus when phosphates are unavailable.

Photic zone - Layer of a body of water that recieves ample sunlight for photosynthesis (usually less than 100m).

Photosynthsis - The process by which plants convert carbon dioxide and water into carbohydrates and oxygen. The carbohydrates are then available for use as energy by the plant or other consuming organisms. (CO₂+ H₂O +SUNLIGHT= C₆H₁₂O₆ + O₂ ). This process is also referred to as "primary production."

Phytoplankton - Tiny, free-floating, photosynthetic organisms in aquatic systems, usually suspended in the water column. They include diatoms, desmids, and dinoflagellates.

Piedmont - Uplands or hill country above the "fall line" of coastal rivers where rapids or cataracts tumble down to the level topography where tidal influence begins.

Plankton - Small or microscopic algae and organisms associated with surface water and the water column.

Point Source - A source of pollution that can be attributed to a specific physical location, as in a waster water treatment plant effluent pipe.

Polycyclic Aromatic Hydrocarbon (PAH) - a chemical compound composed of fused six carbon rings.

Polychlorinated Biphenyl (PCB) - a chemical compound composed of a bi-phenyl group and chlorine atoms. - Pertaining to waters with salinities of 18-30 parts per thousand.

Predator - Organism which hunts and eats other organisms. This includes both carnivores, which eat animals, and herbivores, which eat plants.

Prey - Organism hunted and eaten by a predator.

Primary Producers - organisms, such as algae, that convert solar energy to organic substances through the molecule, chlorophyll. Primary producers serve as a food source for higher organisms.

Probable Effects Level (PEL) - An estimate of the concentration of a potentially toxic substance in the sediment above which the substance is likely to cause adverse effects to aquatic organisms.

Propagule - seeds or fragments of vegetation capable of producing new plants.

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R

Raptor - A bird of prey (i.e. osprey, eagle, hawk)

Recruitment - The residue of those larvae that have: (1) dispersed; (2) settled at the adult site; (3) made some final movements toward the adult habitat; (4) metamorphosed successfully, and (5) survived to be detected by the observer.

Red tide - A dense outburst of phytoplankton (usually dinoflagellates) often coloring water red brown.

Resident - Species which are permanent living members of a particular area.

Riparian area - Riparian refers to the area of land adjacent to a body of water, stream, river, marsh, or shoreline. Riparian areas form the transition between the aquatic and the terrestrial environment.

Riparian Forest Buffers - An area of trees, usually accompanied by shrubs and other vegetation, that is adjacent to a body of water which is managed to maintain the integrity of stream channels and shorelines, to reduce the impact of upland sources of pollution by trapping, filtering, and converting sediments, nutrients, and other chemicals, and to supply food, cover, and thermal protection to fish and other wildlife.

Roe - Fish eggs, especially while still massed in the ovarian membrane; called caviar

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S

Salinity - A measure of the salt concentration of water. Higher salinity means more dissolved salts. Usually measured in parts per thousand.

Salt marsh - A coastal habitat consisting of salt-resistant plants residing in an organic-rich sediment accreting toward sea level.

SAV - see submerged aquatic vegetation.

Scute(s) - Large dermal keratinous plates (i.e. the bony armor of a sturgeon).

Sediment - matter that settles and accumulates on the bottom of a body of water or waterway.

Sessile - Immobile because of an attachment to a substrate (i.e. oysters).

Siltation - The process by which sedimentary material, or silt, is suspended and deposited in a body of water.

Spat - Juvenile, newly attached oysters (i.e. oyster spat).

Spawn - To release eggs and/or sperm into water.

Species - A population or group of populations that are in reproductive contact but are reproductively isolated from all other populations.

Sprawl - A form of land development that moves outward from urban areas in a manner which creates large areas of relatively low density.

Submerged Aquatic Vegetation (SAV) - rooted vegetation that grows under water in shallow zones where light penetrates. Also known as "Bay grasses".

Substrate - "Supporting surface" on which a sessile organism lives and grows. The substrate may simply provide structural support, or may provide water and nutrients. A substrate may be inorganic, such as rock or soil, or it may be organic, such as wood.

Subtidal - Submerged, not exposed at the lowest tide.

Storm Flow - rainfall runoff that reaches a stream channel during, or soon after a rainfall event that causes high rates of discharge.

Swamp - a wetland dominated by woodsy vegetation.

Swim Bladder - an organ regulating the buoyancy in most teleost (bony) fishes.

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TUV

Terrestrial - Living on land, as opposed to marine or aquatic.

Tides - Periodic movement of water resulting from gravitational attraction between the earth, sun, and moon.

Toxicant - A poisionous or toxic agent which is harmful to living resources either terrestrial or aquatic.

Trend Analysis - a formal statistical process that is used to determine the presence or absence of changes in measures of water quality over time or a geographic area.

Tributary - a body of water flowing into a larger body of water.

Trophic Level - Layer in the food chain in where one group of organisms serves as the source of nutrition of another group of animals.

Turbidity - The decreased clarity in a body of water due to the suspension of silt or sedimentary material.

Vertebrate - Animals with a backbone including fish, amphibians, reptiles, birds, and mammals.

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W

Watershed - a region bounded at the periphery by physical barriers that cause water to part and ultimately drain to a particular body of water.

Wet Deposition - Atmospheric deposition that occurs when precipitation (rain and snow) carries gases and particles to the earth's surface.

Wetland - Low areas such as swamps, tidal flats, and marshes which retain moisture.

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XYZ

Year Class - Most fish species in temperate waters (like those found in the Chesapeake Bay and offshore Virginia) reproduce during a relatively short (one or two month) period each year. That period may be different for each species. Fisheries scientists refer to all of the fish of any species hatched during one annual spawning period as a year class. For mathematical purposes, fishery analysts often treat members of the year class as if all fish were hatched on one day.

Young-of-the-year - All of the fish of a species younger than one year of age. Usually scientists assign an arbitrary "birth date" to all fish of a species hatched over a two or three month period in one year. The fish are then assigned to Age 1 status on that birth date. By convention, this is usually January 1.

Zooplankton - a community of floating, often microscopic animals that inhabit aquatic environments. Unlike phytoplankton, zooplankton cannot produce their own food, and so are consumers.

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