abiotic: the nonliving components of the environment such as rock types, slope, geographic setting and climate that affect ecological functions.
airborne pollutant: any substance introduced into the atmospheric environment that adversely affects the usefulness of a resource.
alien species: species that do not naturally occur within an area and that have usually arrived in the area as a result of human intervention (whether deliberate or accidental). Alien species often have adverse effects on native species as a result of competition. See invasive species.
alkalinity: a measure of the capacity of water to neutralize acid. Alkali substances in water include hydroxides or bases.
aquaculture: the production and husbandry of aquatic animals and plants in a controlled environment.
Atrazine: an herbicide widely used on a variety of crops, notably maize, sorghum and sugar cane, for the pre- and post-emergent control of broad-leaved weeds.
ballast water: fresh or salt water, sometimes containing sediments, held in tanks and cargo holds of ships to increase stability and maneuverability during transit.
biodiversity: the variety of life on Earth, reflected in the variety of ecosystems and species, their processes and interactions, and the genetic variation within and among species.
biotic: the living components of the environment, such as plants, animals, and fungi, that affect ecological functions.
bycatch: harvest of fish or shellfish other than the species for which the fishing gear was set. Examples are blue crabs caught in shrimp trawls or sharks caught on a tuna longline. Bycatch is also often called incidental catch.
carbon dioxide: a greenhouse gas whose atmospheric concentrations have been increasing from pre-industrial (1750-1800) levels of 280 parts per million (ppm) to present day levels of 356-360 ppm, depending on location. CO2 decreases in summertime when plant productivity consumes CO2, and increases in winter when biota are less active and respiration exceeds photosynthesis. A main source of CO2 increase in the atmosphere has been burning of fossil fuels.
carnivore: an animal that eats meat in the form of other animals.
carrying capacity: the maximum number of organisms that can use a given area of habitat without degrading the habitat and without causing stresses that result in the population being reduced.
climate change: a regional change in temperature and weather patterns. Current science indicates a link between climate change over the last century and human activity, specifically the burning of fossil fuels.
concentration (of a solution): the amount of a specified substance in a unit amount of another substance.
conservation: the protection, restoration, or sustainability of natural resources.
consumer: an individual who purchases and uses goods or services.
contaminant: a substance that spoils the purity of something else or makes it poisonous.
dissolved oxygen: the volume of oxygen dissolved in water.
drinking water standards: standards for approximately 90 contaminants in drinking water set under the authority of the Safe Drinking Water Act by the Environmental Protection Agency. Water suppliers may not provide water that doesn’t meet these standards.
ecological restoration: the process whereby an entire ecosystem is brought back to health.
ecosystem: a community of plants, animals, and microorganisms that are linked by energy and nutrient flows, and that interact with each other and with the physical environment. Rain forests, deserts, coral reefs, grasslands, and a rotting log are all examples of ecosystems.
ecotoxicology: an area of study that examines the connection between environmental health and human health.
emissions: release of pollutants into the air from a source.
endangered species: species threatened with extinction. The Florida panther and the California condor are endangered species.
endemic: an organism that is native to a particular country, region or ecosystem; not introduced.
environmental health: well-being based on the health of the surrounding environment.
exhaust: gases ejected from an engine as waste products.
exotic species: introduced species; not native or endemic to the area in question.
fertility: the state of being fertile; capable of producing offspring.
fertilizer: a material that is added to soil to increase its fertility and enhance plant growth; includes manure (a natural fertilizer) and synthetic materials made from nitrogen, phosphorus, and potassium compounds.
fisher: someone whose occupation is catching fish. Synonymous with fisherman.
fishery/fisheries: the occupation or industry of catching, processing, and selling fish and shellfish; an area where fish or shellfish are caught.
food chain: a lineup of organisms from producers (plants) to consumers (other plants, animals, and fungi), with each organism feeding on or getting nutrients from the previous organism.
food web: the interconnected feeding relationships in an ecosystem. These relationships can be complex; some organisms may feed on more than one trophic level, or changes may occur depending on a species’ life history stages or the availability of food.
fossil fuels: fuels formed millions of years ago from decayed organisms. Oil, coal, and natural gas are all fossil fuels. See also nonrenewable energy.
fuel-efficient: a way of describing any system whose fuel input is well matched to its productive output.
gill nets: a type of fishing net that catches fish by their gills or gill covers.
ginkgo: a type of Chinese tree having fan-shaped leaves and fleshy yellow seeds; exists almost exclusively in cultivation especially as an ornamental street tree.
global warming: the hypothesis that Earth’s atmosphere is warming because of the release of “greenhouse gases,” such as carbon dioxide. These gases are released into the air from burning gas, oil, coal, wood, and other resources and trap heat in an action similar to that of the walls of a greenhouse.
greenhouse effect: the holding of heat in Earth’s atmosphere by certain gases such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Some scientists predict that the temperature and sea level rise associated with global warming could adversely affect biodiversity.
greenhouse gases: several gases that allow Earth’s atmosphere to hold solar radiation by absorbing heat radiated back from Earth’s surface. These gases include carbon dioxide, methane, water vapor, and nitrous oxide.
groundwater: water beneath the surface that can be collected with wells, tunnels, or drainage galleries, or that flows naturally to Earth’s surface via seeps or springs.
habitat: the area where an animal, plant, or microorganism lives and finds the nutrients, water, sunlight, shelter, living space, and other essentials it needs to survive. Habitat loss, which includes the destruction, degradation, and fragmentation of habitats, is the primary cause of biodiversity loss.
heat-trapping gases: any of several dozen gases in Earth’s atmosphere that absorb infrared energy radiated back from Earth. The two major gases are water vapor and carbon dioxide; others include methane, chlorofluorocarbons, and nitrogen oxides.
herbivore: an animal that eats plants.
hormones: chemical substances secreted by organs or parts of the body, especially the endocrine glands, into the bloodstream. Each hormone has a specific regulatory or functional effect.
hypothesis: a statement consisting of an action that can be tested and a predicted result. Making a hypothesis is part of scientific inquiry.
indicator species: those species that can offer early warning signs of ecological stresses.
infertility: diminished or absent ability to conceive.
infrared energy: electromagnetic radiation relating to the range of invisible wavelengths from about 750 nanometers (.00002 inches) which is just longer than red in the visible spectrum, to about 1 millimeter (.04 inches).
introduced species: organisms that have been brought into an area in which they do not naturally occur. Introduced species can compete with and cause problems for native species. Introduced species are also called exotic, non-native, and alien species.
invasive species: species not endemic to a habitat, that competes with native species for food and space, and typically causes economic and/or environmental harm. See alien species.
London plane tree: trees from the genus Platanus in the order Hamamelidales.
longlines: fishing tackle involving a horizontal line fit with hooks and held by floats.
limiting factor: the least abundant component of a system — usually the one component to which the application of a given amount of effort will pay the greatest returns.
native species: species that occur naturally in an area or a habitat. Also called indigenous species.
nitrogen: a chemical element in the periodic table with the symbol N, atomic number 7 and listed as 14th of the 107 total elements. A common typically colorless, odorless, tasteless gas, nitrogen constitutes 78 percent of Earth’s atmosphere and is a constituent of all living tissues — important for plant growth and found in many commercial fertilizers. It is often washed through a watershed into a stream or river where, if there is too much in the water, it acts as a pollutant.
non-native species: introduced species not native or endemic to the area in question.
nonpoint source pollution: pollution from numerous widespread locations or sources that have no well-defined points of origin and may originate from land use activities and/or from the atmosphere. Examples include leaching of excess fertilizer from fields and acid rain.
ocean uptake: the process whereby the ocean takes up materials such as heat, carbon, oxygen, and other chemicals.
omnivore: an organism whose diet consists of a wide variety of foodstuffs, including plants and animals.
pesticides: chemicals that kill or inhibit the growth of organisms that people consider undesirable. Fungicides (which kill fungi), herbicides (which kill plants), and insecticides (which kill insects) are types of pesticides.
pH: a measure of a substance’s acidity or alkalinity. The term pH translates literally to pondus hydrogenii, which means “potential hydrogen.” The terminology refers to acidity being due to a predominance of hydrogen ions in a water containing solution.
phytoplankton: tiny, free-floating, photosynthetic organisms in aquatic systems including diatoms and dinoflagellates.
point source pollution: the opposite of non-point source pollution. Pollution that comes from a single source and that may be traced back to a single source, such as a pipe. One example of point source pollution would be a pipe that discharges wastewater from a house into a creek. A pipe is an example of a point source.
predator: an animal that hunts and kills other animals for its food.
prey: an organism that is hunted and eaten by a predator.
Secchi (disk) transparency: a method used to get a quick, simple, and accurate measure of water clarity. The method uses a black and white disc, called a Secchi disk that is lowered into the water until it just disappears from sight-this depth measurement is recorded. The deeper the measurement, the clearer the water. This method gives a general indication of problems with algae, zooplankton, water color, and silt.
species: a group of organisms that has a unique set of characteristics, like body shape and behavior, that distinguishes them from other organisms. Individuals within the same species can typically reproduce with each other to produce fertile offspring. Species is the basic unit of biological classification.
sustainable: meeting the needs of the present without compromising the health of the planet or the ability of future generations to meet their own needs.
sustainability: meeting the needs of the present without compromising the ability of future generations to meet their own needs, or the health of the planet.
threatened species: a way to describe organisms that are likely, in the near future, to become endangered.
toxicity: the capacity of a material or organism to cause harm to another living organism.
trade-off: an exchange of one thing in return for another; especially relinquishment of one benefit or advantage for another regarded as more desirable.
tragedy of the commons: a term coined by Garrett Hardin describing the inexorable process of degradation of communal resources due to selfish self-interest of “free riders” who use or destroy more than their fair share of common property.
trawl nets: a conical fishnet dragged through the water or, in the case of bottom trawl, along the seafloor. This is one of the most destructive types of fishing equipment.
turbidity: a measure of the amount of light scattered and absorbed by water because of the suspended matter in the water.
watershed: a geographic area that drains into a single river system and its tributaries.
wetland: an area that, at least periodically, has waterlogged soils or is covered with a relatively shallow layer of water. Bogs, freshwater and saltwater marshes, and freshwater and saltwater swamps are examples of wetlands.
zooplankton: small, often microscopic animals that drift in currents, feed on detritus, phytoplankton, and other zooplankton, and are preyed upon by fish, shellfish, whales, and other zooplankton.