Glossary

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

Abundance index - Information obtained from samples or observations that is used to measure the weight or number of fish that make up a stock.

Acid rain - Natural rainfall that contains nitric and sulfuric acids due to nitrogen oxide (NOx) and sulfur dioxide discharged into the air by industries, power plants, automobiles and other emission sources.

Air deposition - An airborne pollutant (often nitrogen) that falls onto the land and runs off into the water, or falls onto the water itself.

Airshed - A 570,000-square-mile area where emission sources contributing the most airborne nitrates to the Bay originate. The Chesapeake Bay's airshed stretches north to Canada, west to Ohio and south to South Carolina.

Algae - Tiny, single-celled planktonic plants. Algae, or phytoplankton, are the primary producers of food and oxygen in the Bay food web.

Algae bloom - A dense population of algae fueled by excess nutrients. Algae blooms rob the Bay's aquatic life of sunlight and dissolved oxygen.

Allowance - The amount of pollution a source is allowed to discharge during a given period of time.

Amphibian - Cold-blooded vertebrates without scales that live both on land and in water. Their skin is moist and absorbent, and they lay their eggs in water. Common Bay region amphibians include frogs, toads and salamanders.

Amphipod - A small, shrimp-like crustacean.

Anadromous - Fish that spend most of their lives in salt water but must migrate to freshwater tributaries to spawn. Sturgeon and shad are both anadromous fish.

Anaerobic - Not containing oxygen or not requiring oxygen.

Angler - Someone who fishes recreationally with a hook, line and rod.

Anoxia - A condition where no oxygen is present in the water. Also called a "dead zone."

Anthropogenic - Caused by humans.

Aquaculture - The farming of plants and animals that live in water, such as fish or shellfish.

Aquatic - Living in water.

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.

Arachnid - A group of animals that have four pairs of legs and a body divided into two segments. Spiders, ticks, scorpions and mites are all arachnids.

ariakensis -

Arthropod - A diverse group of invertebrates that have jointed legs and an exoskeleton, or external skeleton. Aquatic arthropods include horseshoe crabs and crustaceans like blue crabs and barnacles. Terrestrial arthropods include insects, scorpions and spiders.

Artificial reef - An underwater structure made of artificial substances (such as concrete or metal) that mimics oyster reefs and provides habitat for aquatic species that live on or around aquatic reefs.

Atmospheric deposition - When pollutants in the air fall onto the land or water. Pollution that falls with rain or snow is called wet deposition, and pollution that falls without precipitation is called dry deposition.

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B

Backwater - A still body of water or a still portion of a larger body of water that is unaffected by the flow of the larger body of water. A small stagnant branch of a river would be considered a backwater.

Baseflow - The portion of river flow that comes from groundwater, rather than runoff.

Baseline - The numeric level of pollution coming from a source during a particular time period, which is used as a standard to measure future reduction goals and allowances against.

Basin - An area of land that drains into a particular river, lake, bay or other body of water. Also called a watershed.

Bathymetry - The varying physical characteristics—including depth, contour and shape—of the bottom of the Bay and other bodies of water.

Bay jurisdictions - Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia

BayScapes - Colorful, environmentally sound landscapes that provide wildlife habitat; slow and filter polluted runoff; and require less mowing, fertilizer and pesticides.

Benthic - Bottom-dwelling. Benthic organisms spend at least part of their lives in, on or near the bottom of streams, rivers, lakes or the Bay.

Benthic macroinvertebrate - Bottom-dwelling invertebrates that can be seen with the unaided eye. Benthic macroinvertebrates are used by state and federal water resource agencies to assess stream health.

Benthos - Plants and animals that live at the bottom of the Bay, including worms, shellfish and bottom-feeding finfish.

Best management practices (BMPs) - The most effective and practical ways to control pollutants and meet environmental quality goals. BMPs exist for forestry, agriculture, stormwater and many other sectors.

Bioaccumulation - When chemical contaminants accumulate in the tissues of a living animal, typically increasing in concentration as you move up the food chain. For example, a small fish eats contaminated algae, then a bigger fish eats many contaminated small fish, and a human eats the bigger, now-contaminated fish.

Biological diversity - The variety of life in all forms, levels and combinations, including ecosystem diversity, species diversity and genetic diversity.

Biological nutrient removal (BNR) - Technology that removes nitrogen and phosphorus during wastewater treatment.

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

Bioretention site - Also called a rain garden; an innovative method of stormwater management that retains rainwater and uses plants and layers of soil, sand and mulch to reduce the amount of nutrients and other pollutants that enter local waterways.

Biota - The flora and fauna of a region.

Bivalve - A mollusk with two shells that are connected by a hinge. Clams and oysters are bivalves.

Bloom - A dense population of algae fueled by excess nutrients. Algae blooms rob the Bay's aquatic life of sunlight and dissolved oxygen.

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

Brackish - A combination of fresh and salt water. Most of the water in the Bay is brackish.

Bycatch - Fish, sea turtles, sea stars and other aquatic animals that are unintentionally caught in fishing gear. Bycatch is usually thrown back into the water dead or dying.

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C

Canopy - The top layer of a forest. The canopy shades and protects animals and plants below, while also intercepting and slowing rainfall.

Cap - The total amount of nutrients or sediments allowed to be discharged into a given water body. The cap is the baseline minus the pollutant load that needs to be reduced to meet a water quality or restoration goal.

Cap load - The maximum amount of nutrients and sediments that can be allowed to flow into a waterway and still have it meet water quality criteria.

Cap load allocations - Based on each tributary's nutrient and sediment input to the Bay, the total Chesapeake Bay pollution load is divided proportionally to each tributary and jurisdiction. Cap load allocations show where the nutrient and sediment loads will most effectively be reduced to achieve restoration goals.

Carapace - A hard shell covering the back of an animal, such as a crab or turtle.

Carnivore - An animal or plant that eats meat.

Carrion - The rotting flesh of a dead animal.

Catadromous - Fish that spend most of their lives in freshwater tributaries but must migrate to salt water to spawn. The American eel is the only catadromous fish in the Chesapeake Bay region.

Cephalopod - A type of mollusk. The brief squid is the only cephalopod common to the Chesapeake Bay.

Chesapeake -

Chlorophyll a - The predominant type of chlorophyll found in algae. Chlorophyll a is used as an indicator of nutrient pollution in the Bay and its tributaries.

Cilia - Tiny, projecting "hairs" on a cell or microscopic organism that beat rhythmically to aid in movement.

Clutch - A group of eggs laid together at one time.

Coastal plain - The level land downstream of the piedmont and fall line, where soils are generally finer and fertile and rivers are influenced by the tide.

Coliform bacteria - A group of bacteria primarily found in human and animal intestines and wastes. Coliform bacteria (such as E. coli) are widely used as an indicator of the presence of such wastes in water.

Commensal - A two-species association in which there is a positive effect on one species and neither a positive nor a negative effect on the other.

Conical - Shaped like a cone.

Conifer - Any needle-leaved or scale-leaved cone-bearing tree or shrub, such as pines, spruces and cypress.

Consumer - Any organism that consumes other organisms (living or dead) to meet its energy needs.

Contaminant - Anything that makes the water or land impure, unclean or polluted.

Copepods - Small, abundant planktonic crustaceans that are important food for fish.

Crustaceans - Aquatic arthropods (invertebrates) that have gills and jointed legs. Crabs, shrimps, barnacles, amphipods and isopods are all crustaceans.

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D

DDT - A pesticide used widely in the mid-20th century to control mosquitoes. DDT was banned after it was found to cause bald eagles and other birds to lay eggs with brittle shells that would crack easily, causing populations to decline.

Delmarva Peninsula - The land separating Chesapeake Bay from the Atlantic Ocean. The Delmarva Peninsula is made up of parts of three states: Deleware (Del-), Maryland (-mar-) and Virginia (-va).

Denitrification - The process by which nitrates are reduced to gaseous nitrogen.

Dermo - A parasitic oyster disease that many Chesapeake Bay oysters contract in their second year.

Designated use - The description of an appropriate intended use by humans and/or aquatic life for a water body. Designated uses for a water body may include recreation, shellfishing, water supply and/or aquatic life habitat.

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

Detrivore - Any organism that gets most of its nutrients from the detritus in an ecosystem.

Diatoms - Microscopic algae with plate-like structures made of silica. Diatoms are considered a good food source for zooplankton.

Dinoflagellate - A type of algae with long, whip-like structures called flagellates.

Dissolved inorganic nitrogen (DIN) - Nitrogen that is readily usable by plants.

Dissolved oxygen (DO) - The amount of oxygen that is present in the water. It is measured in units of milligrams per liter (mg/L), or the milligrams of oxygen dissolved in a liter of water. Just like humans, all of the Bay's living creatures need oxygen to survive.

Diurnal - An animal that is active during daylight.

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

Dorsal - Relating to or situated on an animal's back.

Drainage basin - An area of land that drains into a particular river, lake, bay or other body of water. We all live in a drainage basin: some are large (like the Chesapeake), while others are small (like your local stream or creek). Also called a watershed.

Dry deposition - Pollutants in the air that fall onto the land or water as dry particles, without the aid of precipitation.

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E

Easement - A limited right to use a part of land owned by another person or organization.

Ebb tide - A falling tide.

Echinoderm - A marine invertebrate animal that has tube feet and five-part radial symmetry. Sea stars and sea cucumbers are both echinoderms, which means "spiny-skinned."

Ecology - The study of interrelationships between living things and 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, depending on each other either directly or indirectly.

Effluent - Discharge of liquid waste from a wastewater treatment facility, factory or industry to a local waterbody.

Emergent - Growing in water, with the majority extending above the water's surface.

Emissions - Pollution released or discharged into the air from natural or man-made sources, including vehicle tailpipes, smokestacks and aerosol spraying.

Endangered species - A species that is in immediate danger of becoming extinct and needs protection to survive.

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

Endocrine disruptors - Synthetic chemicals that disrupt normal endocrine system functions in humans and wildlife by blocking or mimicing hormones. Known endocrine disruptors include PCBs, dioxins, DDT and some other pesticides.

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

Environmental data - Any measurements or information that describe environmental processes, location or conditions; ecological or health effects and consequences; or the performance of environmental technology. For EPA, environmental data include information collected directly from measurements, produced from models and compiled from other sources such as databases or literature.

Environmental technology - An all-inclusive term used to describe pollution control devices and systems, waste treatment processes and storage facilities, and site remediation technologies and their components that may be utilized to remove pollutants or contaminants from the environment or prevent them from entering the environment.

Epifauna - Animals that live either attached to a hard surface (for example, on rocks or pilings) or move on the surface of bottom sediments. Epifauna include oysters, mussels, barnacles, snails, starfish, sponges and sea squirts.

Epiphyte - A plant that grows upon another plant. The epiphyte does not "eat" the plant on which it grows, but 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 by wind, water or ice, either occurring naturally or as a result of land use practices.

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

Estuary - A partially enclosed body of water where fresh water from rivers and streams mixes with salt water from the ocean. It is an area of transition from land to sea.

Euryhaline - Used to describe aquatic organisms that tolerate a wide range of salinities.

Eutrophic - An aquatic system with high nutrient concentrations, which fuels algal growth. This algae eventually dies and decomposes in a process that reduces the amount of dissolved oxygen in the water.

Eutrophication - The process of excess nutrients accelerating the growth of algae, ultimately depleting the water of dissolved oxygen.

Exoskeleton - Hard outer shell that provides an invertebrate with support and protection. Blue crabs and other crustaceans have exoskeletons.

Exotic species - Any introduced plant or animal species that is not native to a region. Exotic species are not always considered a nuisance or invasive.

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

Extinct species - A species that has disappeared from existence due to either natural or human-induced means.

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F

Fall line - The boundary between the Piedmont Plateau and the Coastal Plain, ranging from 15 to 90 miles west of the Bay. Waterfalls and rapids clearly mark this line, which is close to Interstate 195.

Fecundity - The number of eggs produced per female during a spawning season.

Filter feeder - An organism that feeds by pumping large volumes of water through its gills or mouth and filters out plankton and other particles. Oysters and menhaden are both filter feeders.

Fishing mortality rate - The percentage of fish removed from a species' population due to commercial fishing.

Flagellum - A long, threadlike or whip-like appendage found in certain cells or unicellular organisms that helps the cells move.

Flood tide - A rising tide.

Food chain/web - The feeding process that links organisms in an ecosystem. A food chain is formed as one organism eats another. Each organism in a food web supplies the fuel needed to sustain other life forms.

Freshet - An increase of water flow into the Bay during late winter or spring due to increased precipitation and snow melt in the watershed.

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G

Gastropod - The largest class of mollusks. Gastropods have a one-piece shell (univalve) or no shell at all, and travel by using a single large muscular foot. Snails and slugs are gastropods.

Geographic Information System (GIS) - A computer program used to view, store and analyze maps and other geographic information.

Groundwater - Water that is stored underground in cracks and spaces in rock and soil.

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H

Habitat - The place and conditions in which an organism lives, feeds and/or breeds.

Harful algae bloom - An algae bloom that produces harmful chemicals that are toxic to humans and aquatic life.

Heavy metals - Any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations.

Herbaceous - Plants without woody stems.

Herbivore - An animal that eats plants.

Hermaphroditic - A plant or animal that has both male and female reproductive organs and secondary sexual characteristics.

Hybridize - To crossbreed a plant or animal.

Hydrology - The way water moves and is distributed via precipitation, runoff, storage and evaporation.

Hypoxia - A condition in which oxygen levels in water are very low.

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I

Impaired waters - Waterways that do not meet state water quality standards. Under the Clean Water Act, section 303(d), states, territories and authorized tribes are required to develop prioritized lists of impaired waters.

Impervious - A surface or area that is hardened and does not allow water to pass through. Roads, rooftops, driveways, sidewalks, pools, patios and parking lots are all impervious surfaces.

Indigenous species - A species that is native to the Chesapeake Bay region. It evolved on the North American continent and was present at the time of European colonization.

Infauna - Animals and bacteria of any size that live in bottom sediments. Worms and clams are considered infauna. They form their own community structures within bottom sediments, connected to the water by tubes and tunnels.

Infrastructure - The physical systems that support community function, including roads, sewers and water lines.

Insectivorous - An animal that feeds on insects.

Integrated pest management (IPM) - A sustainable pest management approach that combines the use of biological, cultural, physical and chemical tactics to minimize economic, health and environmental risks.

Intersex - An animal (usually a fish) that displays both male and female characteristics. Intersex in fish has been linked to exposure to hormone-disrupting compounds such as pharmaceuticals, personal care products, herbicides, pesticides and agricultural products.

Intertidal - The area of shoreline between the high tide and low tide marks.

Introduced species - A species that has been intentionally or inadvertently brought into a region or area. Also called an exotic or non-native species.

Invertebrate - An animal that lacks a backbone. Aquatic invertebrates include squids, shrimps, crabs, mollusks and sea stars.

Isopod - A tiny, bug-like crustacean.

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J

Jetty - A wall or other barrier built out into a body of water to shelter a harbor, protect a shoreline from erosion and/or redirect water currents.

Juvenile - Any member of a species that is not yet sexually mature. Often used interchangeably with young of the year (YOY).

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K

Keystone species - A species that affects many other organisms in an ecosystem. If a keystone species substantially increases or decreases in population, it may have a cascading effect on the rest of the ecosystem.

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L

Land cover - Anything that exists on and is visible from above the earth's surface. Examples include water, vegetation and exposed or barren land.

Land use - The way land is used by humans. Forest, agricultural land and urban/suburban land are all land uses.

Larva - The tiny, newly hatched stage of many insects and aquatic animals.

Light attenuation - Reduction in the amount of light that can penetrate through the water, usually caused by excess suspended sediment or algae blooms.

Littoral zone - The intertidal area of the shoreline, between the high tide and low tide marks.

Load - The amount of a type of pollution that the Bay and its tributaries receive.

Low-impact development (LID) - Innovative stormwater management practices that mimic a site's pre-development hydrology. LID uses design techniques that reuse runoff and allow it to soak into the soil, helping to protect local water quality.

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M

Macroinvertebrates - Large, generally soft-bodied organisms that lack backbones.

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

Mainstem - The region of Chesapeake Bay extending from the Susquehanna River to the mouth of the Bay, not including the tributaries.

Mammal - Warm-blooded vertebrates that give birth to and nurse live young; have highly evolved skeletal structures; are covered with hair, either at maturity or at some stage of their embryonic development; and generally have two pairs of limbs, although some aquatic mammals have evolved without hind limbs.

Mandibles - Jaw-like organs on some invertebrates that are used for seizing and biting food.

Marine - A species that lives in the ocean.

Marsh - A border habitat that connects shorelines to forests and wetlands. Marshes are found in fresh, brackish and salt water areas.

Maxilliped - One of three pairs of claw-like structures located near the mouth on the heads of crustaceans.

Megalops - A second larval form of the blue crab.

Mesohaline - Moderately salty waters with salinities that range from 5 to 18 parts per thousand (ppt).

Mesotrophic - An aquatic system that is somewhere between eutrophic (nutrient enriched) and oligotrophic (nutrient poor).

Micro-organism - An organism that can only be seen with a microscope.

Micron - A unit of measurement equal to one thousandth of a millimeter.

Migratory - A species that moves from one habitat or region to another on a regular or seasonal basis.

Mollusk - A phylum of invertebrates that includes bivalves (clams, oysters and mussels), gastropods (snails) and cephalopods (squids).

Molt - Shedding of the exoskeleton prior to new growth. For example, blue crabs and other crustaceans must molt to grow.

Monoecious - A single plant that has both male and female flowers.

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

Mycobacteriosis - An infectious disease that causes inflammation, tissue destruction and formation of scar tissue in organs of striped bass.

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N

Native species - A species that is native to the Chesapeake Bay region. It evolved on the North American continent and was present at the time of European colonization.

Natural infrastructure - Natural physical systems that support life, such as water cycles, nitrogen cycles and water purification.

Nearshore - The relatively shallow waters between the shoreline and deeper, open waters.

Needle - A long, slender leaf found on loblolly pines and other evergreens.

Nekton - Organisms that are able to swim through the water column and move against currents. Nekton include fish, blue crabs, whales and rays.

Nematocyst - Stinging cells found on jellyfish and anemones. The "sting" is caused by a coiled, thread-like tube that is propelled outward for defense and to capture food.

Nesting - When a bird makes, repairs or lives in a nest in preparation for giving birth to young.

Niche - The particular area within a habitat that an organism lives and functions in.

Nitrification - The process through which ammonia is oxidized into nitric acid or another type of nitrate or nitrite. Biological nitrification is a key step in nitrogen removal in wastewater treatment.

Nitrogen - A type of nutrient contributing to the Bay's poor water quality. While nitrogen is needed for plant growth, human activities—from driving cars to applying fertilizers—contribute more nitrogen than the Bay's waters can handle. Elevated nitrogen levels cause more algae to grow, blocking out sunlight and reducing oxygen for fish, crabs and other Bay life.

Nocturnal - An animal that is only active at night.

Non-point source - A source of pollution that cannot be attributed to a clearly identifiable, specific physical location or a defined discharge channel. Non-point source pollution includes nutrients that run off croplands, feedlots, lawns, parking lots, streets and other land uses. It also includes nutrients that enter waterways via air pollution, groundwater or septic systems.

Notochord - A flexible, primitive backbone that forms the main body support of sea squirt larvae and some other marine animals.

Nutrient removal technology (NRT) - Technology that removes nitrogen and phosphorus during wastewater treatment. Also known as biological nutrient removal (BNR).

Nutrient trading - The transfer of nutrient reduction credits, specifically for nitrogen and phosphorus.

Nutrients - Chemicals that plants and animals need to grow and survive. However, excess amounts of nutrients can be harmful to aquatic environments. Elevated levels of nitrogen and phosphorus, two types of nutrients, are the main cause of the Bay's poor water quality and loss of aquatic habitats.

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O

Oligohaline - Brackish waters with low salinities that range from 0.5 to 5 parts per thousand (ppt).

Oligotrophic - A water body or habitat with low concentrations of nutrients.

Omnivore - An organism that will eat both plants and animals.

Open space - An area of land that is valued for natural processes and wildlife, agricultural and sylvan production, active and passive recreation and/or other public benefits.

Overwinter - To remain alive or viable throughout the winter.

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P

Palps - Sensory appendages located near the mouth on many invertebrates that are used to move and sense food.

Parapodia - Paired appendages or feet found on each segment of bristle worms and other segmented marine worms.

Parasite - A plant or animal that lives on or in another species and derives its nutrition and/or protection, often with harmful effects to the host.

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

Perennial - Plants that live for more than two growing seasons. Perennial plants either die back after each season (herbaceous plants) or grow continuously (shrubs).

Pervious - A porous surface that water is able to penetrate through.

Pesticides - A general term for chemical substances that are used to destroy or control insect or plant pests. Many pesticides are manufactured and do not occur naturally in the environment. Others are natural toxics that are extracted from plants and animals.

pH - A measure of the acidity or alkalinity of water.

Phosphorus - A type of nutrient contributing to the Bay's poor water quality. While phosphorus is vital to plant life, human activities—from applying fertilizers to using household cleaners—contribute more phosphorus than the Bay's waters can handle. Elevated phosphorus levels cause more algae to grow, blocking out sunlight and reducing oxygen for fish, crabs and other Bay life.

Photic zone - The layer of water that sunlight is able to penetrate through and reach plants growing underwater.

Photosynthesis - The process by which plants convert carbon dioxide and water into carbohydrates and oxygen. The carbohydrates can then be used as energy by the plant or other consuming organisms. This process is also referred to as "primary production."

Phytoplankton - Tiny, single-celled planktonic plants. Also called algae. Phytoplankton are the primary producers of food and oxygen in the Bay food web.

Piedmont - Uplands or hill country located above the fall line. Rivers and streams in the Piedmont region are not influenced by the tide.

Piscivorous - A fish-eating animal.

Plankton - Free-floating, generally microscopic plants, animals and bacteria. Plankton generally have limited or no swimming ability and are transported by tides and currents. The name plankton, like the word planet, is derived from a Greek root that means "wanderer."

Plastron - The lower part of a turtle's shell.

Plumage - The feathers that cover a bird's body.

Point source - A source of pollution that can be attributed to a specific physical location—an identifiable, end-of-pipe "point." The vast majority of point source discharges of nutrients are from wastewater treatment plants, although some come from industries.

Pollinate - To fertilize a plant by transferring pollen grains from a male plant structure to a female plant structure.

Polychlorinated Biphenyls (PCBs) - A chemical contaminant that was once used as a flame retardant in electrical equipment. Though their production has been banned since 1977, PCBs still pose a risk to humans and wildlife because they persist in the environment.

Polycyclic Aromatic Hydrocarbons (PAHs) - A chemical contaminant that forms when gas, coal and oil are burned. PAHs are common in areas with high rates of development and motor vehicle traffic.

Polyhaline - Salty waters with salinities that range from 18 to 30 parts per thousand (ppt).

ppt - A measurement of water salinity; stands for "parts per thousand."

Predator - An animal that hunts for and eats other plants or animals.

Prey - A plant or animal that is hunted for and eaten by a predator.

Primary producers - Organisms, such as algae, that convert solar energy to organic substances through 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 sediment, above which the toxic substance is likely to cause adverse effects in aquatic organisms.

Proboscis - A long or tubular mouth part in certain insects, worms and spiders that is used for feeding, sucking and other purposes.

Pycnocline - The zone or boundary where the fresher water layer on the surface meets the saltier water layer below. The pycnocline can be a physical barrier that prevents mixing or exchange between the two layers.

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Q

Quality Assurance (QA) - An integrated system of management activities involving planning, implementation, documentation, assessment, reporting and quality improvement to ensure that a process, item or service is of the type and quality needed and expected by the customer.

Quality Assurance Project Plan - A document describing in comprehensive detail the necessary quality assurance, quality control and other technical activities that must be implemented to ensure that the results of the work performed will satisfy the stated performance criteria.

Quality Control (QC) - The overall system of technical activities that measures the attributes and performance of a process, item or service against defined standards to verify that they meet the stated requirements established by the customer; operational techniques and activities that are used to fulfill requirements for quality.

Quality Management - That aspect of the overall management system of the organization that determines and implements the quality policy. Quality management includes strategic planning, allocation of resources and other systematic activities (e.g., planning, implementation, documentation and assessment) pertaining to the quality system.

Quality Management Plan - A document that describes a quality system in terms of the organizational structure, policy and procedures, functional responsibilities of management and staff, lines of authority, and required interfaces for those planning, implementing, documenting and assessing all activities conducted.

Quality System - A structured and documented management system describing the policies, objectives, principles, organizational authority, responsibilities, accountability and implementation plan of an organization for ensuring quality in its work processes, products (items) and services. The quality system provides the framework for planning, implementing, documenting and assessing work performed by the organization and for carrying out required quality assurance and quality control.

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R

Radial - Body parts on an invertebrate that are arranged in a circle around a single center.

Radula - A flexible, toothed organ in the mouths of gastropods used to graze and scrape microscopic algae off hard surfaces.

Rain garden - A garden that uses plants and layers of soil, sand and mulch to retain rainwater, reducing the amount of polluted runoff that reaches storm drains and local waterways.

Range - The geographic area in which a plant or animal lives.

Raptor - A bird of prey, including eagles, ospreys and hawks.

Recruitment - Larvae that have successfully survived through larval stages and can be detected for study or measurement.

Red tide - A dense outburst of dinoflagellates that colors the water reddish-brown. Certain dinoflagellates can produce toxins that kill fish and contaminate shellfish.

Resident - A species that lives permanently in a particular area.

Rhizome - The underground portion of a plant's stem. Rhizomes are usually thick and horizontal, produce roots and have shoots that develop into new plants.

Riparian - The area of land next to a body of water. Riparian areas form the transition between aquatic and land environments.

Riparian forest buffers - Trees and/or other vegetation located along the edge of streams, rivers and other waterways that filter pollution, prevent erosion and provide wildlife habitat.

Riverine - Of a river, relating to or produced by a river.

Roe - The eggs or egg mass of a fish.

Rootstock - The underground portion of a plant's stem, also called a rhizome.

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S

Salinity - A measure of the salt concentration of water. Higher salinity means the water is more salty, while low salinity means that the water is more fresh. Salinity is usually measured in parts per thousand (ppt).

Salinity regime - Water distinguished by its salinity and tidal influence. The major salinity regimes are tidal fresh, oligohaline (brackish), mesohaline (moderately salty) and polyhaline (salty).

Salt marsh - Wetlands that are located in salt water areas and are dominated by cordgrass, also called Spartina. Salt marshes are one of the most productive plant communities on earth.

SAV - Stands for submerged aquatic vegetation, the technical term for underwater bay grasses. SAV help improve water quality and provide important food and habitat for fish, shellfish, invertebrates and waterfowl.

Scavenger - An opportunistic animal that feeds on decaying plants and animals or scraps of food abandoned by other animals.

Scutes - Large, bony plates covering animals such as sturgeon, turtles and sticklebacks.

Sediment - Loose particles of clay, silt and sand. Excess suspended sediment from erosion is one of the largest contributors to the Bay's impaired water quality.

Sedimentation - When sediment settles in an area, covering bottom-dwelling organisms (such as oysters) and filling shipping channels. Also referred to as siltation.

Sessile - An organism that is immobile because it is attached to a hard surface, such as oysters, sea squirts and barnacles.

Shellfish - Aquatic animals, such as clams, crabs, oysters and shrimps, that have a shell or shell-like external skeleton.

Siltation - The process by which sediment is suspended and deposited in a body of water. Also referred to as sedimentation.

Smog - Ozone, particulate matter, humidity and other pollutants that mix together in the air and reduce visibility.

Spat - Juvenile oysters that have just attached to a hard surface.

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

Species - A group of organisms made up of similar individuals that are capable of breeding with one another.

Spicules - Small, needle-like projections that make up the skeleton of a sponge.

Sprawl - Land development that is built away from urban areas and existing town centers, creating large areas of relatively low-density residential and commercial development.

Stamen - The male reproductive organ of a flower.

Stormwater - Any precipitation in an urban or suburban area that does not evaporate or soak into the ground, but instead pools and travels downhill. Stormwater is also referred to as urban stormwater, runoff and polluted runoff. Increased development across the Bay watershed has made stormwater runoff the fastest growing source of pollution to the Bay and its rivers.

Stratification - The division of warmer, lighter fresh water over a layer of saltier and denser water in the Bay. Stratification of the two layers varies within any season depending on rainfall.

Stream bank erosion - Loss of sediment along a stream bank as a result of increased runoff from nearby development. Stream bank erosion degrades stream habitats for wildlife and increases suspended sediments in the water.

Submerged aquatic vegetation (SAV) - Technical term for underwater bay grasses. SAV help improve water quality and provide important food and habitat for fish, shellfish, invertebrates and waterfowl.

Substrate - The surface or material that an organism lives on or in. For example, oyster reefs provide hard substrate for invertebrates to attach themselves to.

Subtidal - The area of shoreline that is always submerged, even at the lowest tide.

Suspended sediments - Tiny particles of clay and silt that become suspended in the water, reducing water clarity and the amount of sunlight that can reach underwater bay grasses. Excess suspended sediment is one of the largest contributors to the Bay's impaired water quality.

Sustainability - Maintaining an ecological balance by avoiding depletion of natural resources.

Swamp - A type of wetland dominated by woody vegetation or trees.

Swim bladder - A gas-filled organ that regulates buoyancy in most bony fishes.

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T

Terrestrial - An organism that lives on the land.

Thicket - A thick, tangled growth of shrubs, bushes and/or small trees.

Threatened - A species that is likely to become endangered if not protected.

Tidal mud flat - The unvegetated area of shore that is exposed during low tide.

Tides - The alternate rising and falling of the sea caused by the gravitational attraction of the earth, sun and moon.

Total maximum daily load (TMDL) - Defines the pollutant load that a water body can acquire without violating water quality standards, and allocates the pollutant loading between contributing point sources and non-point sources.

Toxicant - A toxic agent that is harmful to plants and animals.

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

Tributary - Streams and rivers that eventually flow into a larger water body or the Bay. For example, the James River is a tributary of the Chesapeake Bay.

Tributary strategies - River-specific cleanup plans that detail the actions needed to achieve nutrient and sediment cap load allocations that are developed in cooperation with local watershed stakeholders.

Trophic level - Each step along a food chain; an organism's feeding level.

Turbidity - Decreased clarity in a body of water due to excess suspended sediments.

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U

Understory - The layer of forest located underneath the canopy. The understory is made up of smaller trees and shrubs that grow to replace older trees that die.

Urban forest - The system of trees and associated plants that grow in small groups or under forest conditions on public and private lands in cities, suburbs and towns. This includes the approximately 74.4 billion trees in the U.S. that are located in parks, along streets and around private homes and businesses.

Use attainability analysis (UAA) - A structured scientific assessment of the factors affecting attainment of the designated use component of water quality standards, based on physical, chemical, biological and/or economic factors.

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V

Valve - A shell on a mollusk. Mollusks with two shells (such as clams and oysters) are called bivalves.

Veliger - Free-floating, planktonic larvae of certain mollusks, such as snails, oysters and sea slugs.

Venom - A poisonous fluid produced by an animal that is transmitted by a bite or a sting. Venom is used to capture prey or as a means of defense.

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

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W

Wastewater - Water that has been used in homes, industries and businesses that is not for reuse unless treated by a wastewater facility.

Water clarity - A measure of the amount of sunlight that can penetrate through the water.

Water quality criteria - Water quality conditions necessary to protect aquatic plants and animals.

Water quality standards - Standards that define the goals for a water body by designating its uses, setting criteria to protect those uses, and establishing provisions to protect water bodies from pollutants.

Waterfowl - Any of various birds that swim on water or rely on aquatic environments,including ducks, geese and swans.

Watershed - An area of land that drains into a particular river, lake, bay or other body of water. We all live in a watershed: some are large (like the Chesapeake), while others are small (like your local stream or creek).

Wet deposition - Pollutants in the air that fall onto the land or water with rain or snow.

Wetland - A transitional zone between land and water that is periodically saturated or flooded. Marshes, swamps and bogs are all types of wetlands.

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Y

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

Young of the year (YOY) - All of the fish of a species that were born in the past year, from transformation to juvenile until January 1.

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Z

Zoea - A tiny, semi-transparent larval blue crab.

Zooplankton - Planktonic animals that range in size from single-celled protozoa to larger jellyfish and comb jellies. The zooplankton community is composed of both primary consumers, which eat phytoplankton, and secondary consumers, which feed on other zooplankton.

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