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Abiotic: Physical rather than biological; not derived from living organisms. Synonyms: devoid of life; sterile.
Accidental introduction: An introduction of nonnative aquatic species that occurs as a result of activities other than the purposeful or intentional introduction of the species involved, such as the transport of nonnative species in ballast water or in water used to transport fish, mollusks, or crustaceans for aquaculture or other purposes. Synonyms are unintentional, incidental, and inadvertent introduction.
Adaptation: A trait with a current functional role in the life of an organism that is maintained and evolved by means of natural selection.
Algae: A simple nonflowering plant of a large group that includes the seaweeds and many single-celled forms.
Alien species: With respect to a particular ecosystem, any species—including its seeds, eggs, spores, or other biological material capable of propagating that species—that is not native to a specific area or ecosystem. Because some alien species may be harmful or invasive while others are not, this term should be used with great care. Synonyms include nonindigenous, nonnative, foreign, and exotic species.
Allelochemicals: Chemicals produced in the tissues of plants that inhibit the growth of another species.
Allelopathy: The inhibition of growth in one species of plants by chemicals produced by another species.
Amphibian: A cold-blooded vertebrate animal of a class that comprises the frogs, toads, newts, and salamanders. They are distinguished by having an aquatic, gill-breathing larval stage, followed (typically) by a terrestrial, lung-breathing adult stage.
Anadromous organism: An organism that resides for the most part in marine waters but spawns in freshwater, where juveniles develop before migrating to sea. Examples are salmon, shad, and lamprey.
Analysis: A detailed examination of the elements or structure of something, typically as a basis for discussion or interpretation.
Annual: A plant that lives or grows for only one year or season. Populations persist in time through annual seed germination.
Anode: The positively charged electrode by which electrons leave a device.
Anoxic: Lacking oxygen.
Anthropogenic: Caused by humans.
Aquatic: Of or relating to water, such as an aquatic plant or animal, typically one suitable for a pond or aquarium.
Aquatic ecosystems: An ecosystem in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine and freshwater.
Aquaculture: Underwater agriculture. The cultivation of aquatic animals and plants—especially fish, shellfish, and seaweed—in natural or controlled marine or freshwater environments.
Aquatic invasive species (AIS): A nonindigenous aquatic species that has a negative economic, human health, or ecological impact.
Aquatic nuisance species (ANS): A nonindigenous aquatic species that has a negative economic, human health, or ecological impact.
Aquatic species: All animals and plants, as well as pathogens or parasites of aquatic animals and plants, that are totally dependent on aquatic ecosystems for at least a portion of their life cycle. Bacteria, viruses, parasites, and other pathogens of humans are excluded.
Assumption: A thing that is accepted as true or as certain to happen, without proof.


Bait: Species used to attract fish for recreational fishing, including fish, worms, and other invertebrates.
Baitfish: Fish species commonly sold for use as bait for recreational fishing, such as fathead minnows (Pimepheles promelas).
Ballast: Heavy material that is placed in the hold of a ship or the gondola of a balloon to enhance stability. Ships typically use water for ballast, but historically soil has also been used.
Ballast water: Water used in commercial shipping/cargo vessels to stabilize the vessel. The water is uploaded or discharged, depending on the amount of cargo onboard. It, along with many plankton marine organisms, is taken on board at the port before the voyage begins, and then discharged at the port of destination. Organisms can travel across the world by means of ballast water.
Benthic: Of or pertaining to the organisms that live on the bottoms of lakes or rivers.
Benthic communities: A group of organisms that live on the bottom of an aquatic ecosystem (not planktonic).
Benthification: A change from water column-dominated communities (plankton) to bottom-dwelling organisms (benthon).
Bias: Prejudice in favor of or against one thing, person, or group compared with another, usually in a way considered to be unfair.
Bioaccumulation: The accumulation of a substance, such as a toxic chemical, in various tissues of a living organism at a rate that is faster than the organism can catabolize or eliminate.
BioBlitz: An intense period of biological surveying to record living species within a designated area. Typically led by scientists with naturalists. BioBlitzes are often used to promote public interest in biodiversity.
Biodiversity: The variability among living organisms on the earth, including the variability within and between species and within and between ecosystems.
Biofouling: The undesirable accumulation of microorganisms, plants, and animals on artificial surfaces.
Biofuel: Any fuel that derives from biomass—recently living organisms or their metabolic byproducts, such as manure from cows. It is a renewable energy source, unlike other natural resources such as petroleum, coal, and nuclear fuels.
Biological control (Biocontrol): The use of living organisms to control other living organisms. It frequently involves the introduction of a nonnative predator, herbivore, pathogen, or parasite that interacts with the invasive species in its natural geographic range.
Biomass: An organism's material mass.
Biotic: Of, relating to, or resulting from living things, especially in their ecological relations.
Bioturbation: The disturbance of sediment layers by biological activity.
Bivalve: Aquatic mollusk with a laterally compressed body and a shell consisting of two valves, or movable pieces, hinged by an elastic ligament.
Boreal: Of or relating to the north; northern.
Brackish: Water that is saltier than freshwater but not as salty as seawater.
Brainstorming process: A group creativity technique by which efforts are made to find a conclusion for a specific problem by gathering a list of ideas spontaneously contributed by its members.
Byssal threads: A string-like substance secreted by mussels to allow them to attach to hard substrates like rocks. Byssal threads have “a stiff tether” on one end and a “shock absorber” on the other end.


Carrying capacity: The number or quantity of people or things that can be conveyed or held by a vehicle or container.
Catadromous organism: An organism that spends most of its lifetime in freshwater and migrates to marine waters to breed. An example is the Chinese mitten crab (Eriocheir sinensis).
Cathode: The negatively charged electrode by which electrons enter an electrical device.
Characteristic(s): Typical of a particular person, place, or thing.
Chytrid fungus: An infectious disease spread by a fungus. It’s capable of causing sporadic deaths in some amphibian populations and 100 percent mortality in others.
Clone: An organism or cell, or group of organisms or cells, produced asexually from one ancestor or stock, to which they are genetically identical.
Common name: A name that is based on the normal language of everyday life; this kind of name is often contrasted with the scientific name.
Community (ecology): A group of plants and animals living and interacting with one another in a specific region under relatively similar environmental conditions.
Competition: The simultaneous demand by two or more organisms for limited environmental resources, such as nutrients, food, living space, breeding areas, or light.
Conclusion: A judgment or decision reached by reasoning.
Consensus: General agreement.
Containment: A tool to prevent further transport of existing invasive species or to reduce the impact of existing invaders. Strategies for containment generally combine tools used in prevention and eradication.
Control: Activities to eliminate or reduce the effects of aquatic nuisance species, including efforts to eradicate infestations, reduce populations of aquatic nuisance species, develop means to adapt human activities and facilities to accommodate infestations, and prevent the spread of aquatic nuisance species from infested areas.
Control and management: Eradicating, containing, suppressing spread, reducing population size, or reducing the effects of invasive species and preventing new invasions in a defined area by chemical, biological, or mechanical means.
Copepods: Minute crustaceans that form an important component of the plankton in freshwater and marine environments.
Core area: A geographic zone containing several to many water bodies that are heavily infested with an aquatic nuisance species.
Critical control point: A specific point, procedure, or step in a plan that can be used to reduce, eliminate, or prevent potential hazards.
Cryptogenic species: A species for which record of origin is questionable or unclear. It can be native or nonnative. Because humans have not kept a complete list of species by geographic location from the beginning of human life on the planet, there is no continuous, scientific record of all species and their original location(s) on earth.
Cultivar: A race or variety of a plant that has been created or selected intentionally and maintained through cultivation.
Cultural practices: A non-chemical approach to controlling invasive plants that integrates knowledge of plant growth habit, competitive ability, and life cycle (phenology) with crop-management techniques such as tilling, rotation, cover crops, and selecting appropriate timing and arrangement when planting.


Data: Facts and statistics collected together for reference or analysis.
Detritus: The remains of animals, plants, and minerals that have been destroyed or broken up. Many organisms feed directly on detritus for survival.
Diatoms: A class of planktonic, one-celled algae with skeletons of silica.
Dichotomous key: A tool that allows the user to determine the identity of items in the natural world, such as trees, wildflowers, mammals, reptiles, rocks, and fish.
Dioecious: Characterized by species in which the male and female reproductive organs occur on different individuals; sexually distinct.
Diploid: Having a pair of each type of chromosome, so that the basic (haploid) chromosome number is doubled.
Diploid versus triploid grass carp: Normal grass carp have 48 chromosomes. This is known as the diploid or _N chromosome number. Sterile grass carp are produced in hatcheries by physically shocking the eggs, with temperature (hot or cold) or pressure, immediately after fertilization. The resulting fish are triploids (3N) because each cell has an extra set of chromosomes. Triploids are infertile.
Disease: A disorder of structure or function in a human, animal, or plant, especially one that produces specific signs or symptoms or that affects a specific location and is not simply a direct result of physical injury.
Disking: Working (soil) with a disk harrow.
Dispersal: The action or process of distributing things or people over a wide area.
Diversity: Abundance of different species in a given location.
Dorsal: Of, pertaining to, or situated at the back, or dorsum.
Drainage basin: The catchment basin from which the waters of a stream, marsh, river, lake, or groundwater system are drawn. Multiple small basins may be contained within a larger basin.


Early detection and rapid response (EDRR): The process by which invasive species are detected and controlled early while the populations are still small. Next to prevention, EDRR is the most efficient and least damaging way to control invasives.
Ecology: The branch of biology that deals with the relations of organisms to one another and to their physical surroundings.
Ecological integrity: The extent to which an ecosystem has been altered by human behavior. An ecosystem with minimal impact from human activity has a high level of ecological integrity; an ecosystem that has been substantially altered by human activity has a low level of ecological integrity.
Ecologically harmful nonnative species: Those nonindigenous plants, animals, and pathogens that can naturalize, have high propagation potential, are highly competitive for limiting factors, and cause displacement of or otherwise threaten native plants and animals in their natural communities.
Ecosystem: A system formed by the interaction of biological and physical components. That is, a community of organisms interacting with their physical environment.
Electrofishing: Electrofishing is a common scientific-survey method used to sample fish populations to determine abundance, density, and species composition. The method uses direct-current electricity flowing between a submerged cathode and anode. This affects the movement of the fish so that they swim toward the anode, where they can be caught. When performed correctly, electrofishing results in no permanent harm to fish, which return to their natural state in as little as two minutes after being caught.
Electron: A stable subatomic particle with a negative charge, found in all atoms and acting as the primary carrier of electricity in solids.
Embryo: An unborn or unhatched offspring in the process of development.
Emigration: The act of leaving an area of residence with the intent to settle elsewhere.
Engineering: The branch of science and technology concerned with the design, building, and use of engines, machines, and structures.
Entry potential: The relative ability of an organism to penetrate the borders of a given area within a time interval.
Epifauna: Benthic animals that live on or move over the surface of a substrate.
Epiflora: Benthic plants that live on the surface of a substrate.
Epiphyte: A plant that nourishes itself but grows on the surface of another plant for support.
Eradicate or eradication: The complete elimination of an invasive species from a specific geographic area in the early stages of the species’ colonization of that area. Early eradication is most likely to occur when the species is locally established and fairly contained.
Established species: A nonnative species with a permanent, reproducing population that is unlikely to be eliminated easily through human action or natural causes.
Estuary: The wide part of a river where it nears the sea; fresh- and saltwater mix. Estuaries are often brackish as a result of the mixing of seawater with fresh riverine water. Technically, brackish water covers a range of salinity regimes and may contain between 0.5 and 30 grams of salt per liter—more often expressed as 0.5 to 30 parts per thousand (ppt or ‰).
Eukaria: Any member of the Eukarya, a domain of organisms having cells each with a distinct nucleus within which the genetic material is contained. Eukaryotes include protoctists, fungi, plants, and animals.
Eutrophic: Having waters rich in mineral and organic nutrients that promote a proliferation of plant life, especially algae, which reduces the dissolved oxygen content and often causes the death of other organisms.
Eutrophication: Process of increasing mineral and organic nutrients in water that promotes a proliferation of plant life, especially algae, which reduces the dissolved oxygen content and often causes the death of other organisms.
Evolution: The process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.
Exotic: Originating in or characteristic of a distant foreign country.
Exotic species: A species that is not native to a designated ecosystem or geographic area.
Exposure time: An act of subjecting, or an instance of being subjected, to an action or an influence over time.


Fauna: The animal life of a region or geological period.
Fecundity: The capacity of producing offspring, especially in abundance.
Filter feeding: Feeding by taking water in through some body part (a siphon in clams, for example) and filtering food particles (such as phytoplankton, zooplankton, copepods, and bacteria) from the water via specialized body parts (such as gill rakers in fish).
Flora: The plant life of a region or geological period.
Food chain: A succession of organisms in an ecological community that constitutes a continuation of food energy from one organism to another as each consumes a lower member and in turn is preyed upon by a higher member.
Food webs: A complex of interrelated food chains in an ecological community.
Foot: Referring to mollusks, this is the muscular base or bottom of a mollusk that expands and contracts and allows the snail to move forward or allows a clam to dig.
Foreign species: A species that is not native to a designated ecosystem or geographic area.
Fouling Species: Aquatic species whose growth form is encrusting. They tend to cover that which they live upon, including hulls of vessels, pier pilings, or water intake structures.
Frequency: The rate at which something occurs or is repeated over a particular period of time or in a given sample.
Freshwater species: Aquatic species native to fresh (not salty) water. Some species spend different portions of their life cycles in fresh, brackish, and marine waters. They are usually classified by the waters in which they spend the largest portion of their adult lives.
Fry: A pre-juvenile and post-larval stage of fish development.


Gastropod(a): A mollusk of the large class Gastropoda, such as a snail, slug, or whelk.
Generalist species: Species with the ability to live in many different places while tolerating a wide range of environmental conditions.
Genetic variability: A measure of the tendency of individual genotypes in a population to vary from one another.
Gestation: The process of carrying or being carried in the womb between conception and birth.
Gill rakers: Bony, finger-like projections of the gill arch filaments, whose function is to retain food organisms.
Gregarious: The tendency of species to associate with others of the same species or grow in a cluster or colony. Invasive species tend to be gregarious.


Habitat: The area where a species has the necessary food, water, shelter, and space to live and reproduce.
HACCP (Hazardous Analysis and Critical Control Points): A systematic, preventive-planning approach to identify when and how an invasive species should be removed from an invasion pathway.
Hazard or hazardous: A danger or risk.
Herbaceous: Relating to or characteristic of an herb, as distinguished from a woody plant.
Herbivore: An animal that feeds primarily on plants.
Herbivory: The consumption of plant material by an herbivore.
Hermaphrodite: An individual having the reproductive organs and many of the secondary sex characteristics of both sexes.
Hitchhikers: Species that obtain a free ride from a passing vehicle or water. Aquatic invasive species that secure transport to a new location by clinging to or attaching to a boat or motor, waders, clothing, people, boat trailers, or other hard surfaces, or by floating or remaining in suspension in water transported from one area to another. The water is typically carried in ballast tanks, bait buckets, live wells, and fry or aquaculture-delivery tanks.
Humidity: A quantity representing the amount of water vapor in the atmosphere or a gas.
Hybrid: The offspring of genetically dissimilar parents or stock, especially the offspring produced by breeding plants or animals of different varieties, species, or races.
Hypothesis: A tentative explanation for an observation, phenomenon, or scientific problem that can be tested by further investigation.


Immigration: The action of coming to live permanently in a new area.
Impact: To have a strong effect on someone or something.
Inadvertent introduction: An introduction of nonindigenous species that occurs as a result of activities other than the purposeful or intentional introduction of the species involved. Synonyms are unintentional, accidental, and incidental introduction.
Incidental introduction: An introduction of nonindigenous species that occurs as a result of activities other than the purposeful or intentional introduction of the species involved. Synonyms are unintentional, accidental, and inadvertent introduction.
Indeterminate maturation: Maturing at different times.
Indigenous: Naturally occurring in a specific geographic area or ecosystem. Synonyms include native species.
Intentional introduction: An introduction of nonindigenous species that occurs as a result of activities to purposefully bring species to a new area.
Introduced species: Organism(s) that have been moved to a nonnative ecosystem or geographic area through human activity.
Invasive: Tending to spread prolifically and undesirably or harmfully.
Invasive species: Nonindigenous species whose introduction and proliferation cause or are likely to cause economic or environmental harm or harm to human health.


Kingdom: In biology, kingdom is a taxonomic rank that is composed of smaller groups called phyla.


Lateral: Of or pertaining to the side.
Leaf litter: Dead leaves that accumulate in the fall. Leaf litter is an important component of the aquatic food web.
Lentic ecosystems: Ecosystems in still water, such as lakes, ponds, or wetlands.
Life cycle: The series of changes in the life of an organism, including reproduction.
Limiting factor: Environmental conditions that limit the growth, abundance, or distribution of an organism or a population of organisms in an ecosystem.
Litter: The group of young animals born to an animal at one time.
Localized population: A reproducing population of introduced organisms that is confined to a particular area. Possibility for eradication is increased when the organism is contained.
Lotic ecosystems: Ecosystems in moving water, such as streams or rivers.


Macroscopic: Visible to the naked eye; not microscopic.
Management: The process of dealing with or controlling things or people.
Mantle: A significant part of the anatomy of mollusks: it is the dorsal body wall, which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.
Marine debris: Any persistent, solid material that is manufactured or processed and directly or indirectly, intentionally or unintentionally, disposed of or abandoned into the marine environment or the Great Lakes.
Marine species: Aquatic species native to salty or ocean water. Some species may spend a portion of their lives in fresh, brackish, and marine waters. They are usually classified by the waters in which they spend the largest portion of their adult lives.
Masticatory pad: A structure used for chewing. Asian carp rely on their pharyngeal teeth and masticatory pads to crush or process their food.
Mechanical control: A non-chemical approach to controlling invasive species that involves directly manipulating individuals or the population. Examples include hand pulling, manual cutting, harvesting, rolling, dredging, and the placement of barriers to inhibit growth.
Mesic forest: A forest characterized by, or adapted to, a moderately moist habitat.
Metabolites: A substance that is either produced by metabolism or is necessary for or taking part in a particular metabolic process.
Microscopic: An object that is so small as to be visible only with a microscope.
Mobile: Able to move or be moved freely or easily.
Mollusk: An invertebrate with a soft, unsegmented body, usually enclosed in a shell.
Molluscivore: An animal that feeds on mollusks, such as snails, mussels, and clams.
Monitor: To observe and check the progress or quality of something over a period of time.


Native species: A plant or animal species that naturally occurs in an area and has not been introduced from another area, state, or continent. Synonyms include indigenous species.
Natural resources: Materials or substances such as minerals, forests, water, and fertile land that occur in nature and can be used for economic gain.
Naturalized species: A plant or animal species that is not native to an area but has become acclimated to it.
Needs assessment: A systematic process for determining and addressing needs, or "gaps" between current conditions and desired conditions or "wants." The discrepancy between the current condition and wanted condition must be measured to appropriately identify the need.
Niche: The function or position of an organism or population within an ecological community, based on life history, habitat, trophic position (place in the food chain), and geographic range.
Nonnative species: A plant or animal species living outside its natural past or present distribution; includes any part, gamete, seeds, eggs, or propagules of such species that might survive and subsequently reproduce. Not all nonnative species are invasive species. Many are harmless or beneficial. Synonyms include nonindigenous, foreign, alien, and exotic species.
Nuisance species: A plant or animal species that threaten the diversity or abundance of native species or the ecological stability of specific waters, or commercial, agricultural, aquacultural, or recreational activities dependent on such waters. Nuisance species may be native or nonnative.
Nutria: A large, semiaquatic, beaver-like rodent, native to South America. It is kept in captivity for its fur and has become naturalized in many other areas.


Operational definition: The application of operationalization used in defining the terms of a process (or set of validation tests) needed to determine the nature of an item or phenomenon (e.g., a variable, term, or object) and its properties, such as duration, quantity, extension in space, chemical composition, etc.
Operculum: A flattened piece of hard material that acts like a door to the opening of the snail shell and that, when closed, allows the snail to survive harsh conditions and avoid predation.
Organism: Any active, infective, or dormant stage of life form of an entity characterized as living—including vertebrate and invertebrate animals, plants, bacteria, fungi, mycoplasmas, viroids, or viruses.
Ornamental plant: A plant species or cultivar that is grown in gardens and parks for its beauty rather than for commercial or other value.
Outlier: A data point that is significantly different from other points in a data set.
Overfishing: This happens when you deplete the stock of fish in a body of water by too much fishing.
Overpopulation: The condition of having a population so dense as to cause environmental deterioration, an impaired quality of life, or a population crash.


Parasitic: Habitually relying on or exploiting other organisms for resources.
Parthenogenetic or parthenogenesis: An asexual form of reproduction found in females in which growth and development of embryos or seeds occur without fertilization by males. This is not to be confused with hermaphroditic species, which reproduce by themselves because they contain reproductive organs of both genders.
Pathogen: A specific agent causing disease; may be a bacteria, virus, or fungus.
Pathway(s): Natural and human connections that allow movement of species or their reproductive propagules from place to place.
Pedal feeding: Using cilia on the foot to collect sediment organic matter.
Pediveliger: A near-juvenile developmental stage of the clam.
Pelagic community: The pelagic community lives in the water column above the seafloor and below the surface. It consists of free-swimming creatures known as nekton.
Pelagic zone: A section of the water column in a lake or the ocean that is not near shore. In some contexts, the term refers to an area that is not close to the bottom of the sea or a lake. The word pelagic comes from the Greek word pélagos, which means “open sea.”
Perennial: A plant that lives three seasons or more.
Periphyton: A complex mixture of algae, cyanobacteria, heterotrophic microbes, and detritus that is attached to submerged surfaces in most aquatic ecosystems. It serves as an important food source for invertebrates, tadpoles, and some fish.
Pharyngeal teeth: Tooth-like structures in fish. Pharyngeal teeth are on bones derived from gill supports and are used to process foods. The teeth themselves vary according to function.
Pharynx: A section of your throat behind the nasal passages and mouth but before the larynx (voice box).
Phenotypic: Related to the observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences.
Photosynthesis: The process in green plants and certain other organisms by which carbohydrates are synthesized from carbon dioxide and water, using light as an energy source. Most forms of photosynthesis release oxygen as a byproduct.
Phytoplankton: Photosynthetic microorganisms suspended in the water.
Planktivore: An animal that feeds primarily on plankton.
Plankton: The collection of organisms, including algae and protozoans, that float or drift in fresh- or saltwater, especially at or near the surface, and may serve as food for fish and other larger organisms. These are typically small, including algae and protozoans, and invertebrate and vertebrate larvae, but may also include jellies, which can be quite large.
Population dynamics: The branch of life sciences that studies the size and age composition of populations as dynamic systems, and the biological and environmental processes driving them.
Population (ecology): All the organisms of a single species that occur in a specified habitat.
Precautionary principle: The principle that the introduction of a new product or species whose ultimate effects are disputed or unknown should be resisted.
Predation: An interaction between organisms in which one organism (the predator) attacks and feeds upon another organism (the prey).
Predator(s): An animal that naturally preys on other animals.
Prevention: The single best way to limit the impacts of nonnative species is to restrict accidental movement and growth or the deliberate importation of potentially harmful species.
Prey: An animal that is hunted and killed by another for food.
Primary production: The production of organic compounds from inorganic materials, principally through the process of photosynthesis (although chemosynthesis also plays a role).
Primary consumption: The direct consumption of primary producers such as plants, algae, and periphyton.
Project proposal: A detailed description of a series of activities aimed at solving a certain problem.
Prokaryotic: An organism of the kingdom Monera (or Prokaryotae), comprising the bacteria and cyanobacteria, characterized by the absence of a distinct, membrane-bound nucleus or membrane-bound organelles, and by DNA that is not organized into chromosomes.
Propagule pressure: A concept that states that as there is more invasion pressure applied to a system (more individual invasive organism being introduced), there is more of a statistical chance that the organism will be able to establish a population within this new location.


Range: A set of different things of the same general type.
Rate of change: A ratio between a change in one variable relative to a corresponding change in another.
Refuge: A place that provides protection or shelter.
Region: An area or division, especially part of a country or the world having definable characteristics but not always fixed boundaries.
Reproduce or reproduction: The production of offspring by a sexual or asexual process.
Research process: Steps used to collect and analyze information to increase our understanding of a topic or issue.
Response: A reaction to something.
Restoration: An intentional activity that initiates or accelerates the recovery of an ecosystem with respect to its health, integrity, and sustainability. Frequently, the ecosystem that requires restoration has been degraded, damaged, transformed, or entirely destroyed as the direct or indirect result of human activities.
Rhizoids: Long, tubular single cells, or filaments of cells that anchor some marine algae (such as caulerpa) to the sea floor.
Rhizome: A horizontal, usually underground stem that often sends out roots and shoots from its nodes. Rhizomes are underground stems that function as roots (anchor the plant, store food, move and store water and nutrients) and stems (support growth, produce surface for photosynthesis, and reproduce by spreading and fragmenting).
Riparian area: The area of transition between aquatic and terrestrial ecosystems. Riparian areas are valuable ecosystems due to the diversity of plants and animals they support. A healthy riparian area benefits the aquatic ecosystem, as well.
Riparian buffer: A vegetated area (a "buffer strip") near a stream, usually forested, that helps shade and partially protect a stream from the impact of adjacent land uses. It plays a key role in increasing water quality in associated streams, rivers, and lakes, thus providing environmental benefits.
Risk: A danger or hazard.
Runoff: Rainfall not absorbed by soil.


Scientific model: A representation of an idea, an object, or even a process or a system that is used to describe and explain phenomena that cannot be experienced directly. Models are central to what scientists do, both in their research and when communicating their explanations.
Scientific name: A name used by scientists, especially the taxonomic name of an organism that consists of the genus and species.
Seed bank: A collection of dormant seeds that exist in the soil. Depending on the plant species, seeds can remain viable for many years but will not germinate until the correct conditions exist.
Senesce: To grow old and die.
Sessile: Permanently attached or fixed; not free-moving.
Slope: A measure of the steepness of a line, or a section of a line, connecting two points.
Social science: The scientific study of human society and social relationships.
Specialist: Able to thrive in a wide variety of environmental conditions and make use of a variety of different resources.
Specialization: The adaptation of an organism or organ to a special function or environment.
Species: A group of organisms, all of which have a high degree of physical and genetic similarity, that can generally interbreed only among themselves and show persistent differences from members of allied species.
Species introduction: The intentional or unintentional escape, release, dissemination, or placement of a species into a new ecosystem, as a result of human activity.
Stratification: The formation of layers in the water. Each layer is usually associated with a different temperature or oxygen level.
Stewardship: The careful and responsible management of something entrusted to one's care.
Storyboard: A sequence of drawings, typically with some directions and dialogue, representing the shots planned for a movie or television production.
Succession: The gradual and orderly process of ecosystem development brought about by changes in community composition and the production of a climax characteristic of a particular geographic region.
Survival strategy: The plan of action or policy that allows an organism to thrive, especially under adverse or unusual circumstances.
Suspension feeder: An animal that eats by filtering out tiny particles of organic material suspended in the water.


Tally: A current score or amount.
Temperate: A region that undergoes seasonal changes in temperature and moisture; in general, climate in a temperate region is mild and without extremes.
Terrestrial: Living on or in or growing from land.
Thumbnail sketch: Art directors, storyboard artists, and graphic designers, as well as other kinds of visual artists, use the term "thumbnail sketch" to describe a small drawing on paper (usually part of a group) used to explore multiple ideas quickly.
Torsion: In a gastropod mollusk, this is the spontaneous twisting of the visceral hump through 180° during larval development. This is a characteristic of all gastropods.
Triploid: Having a chromosome number that is three times the basic or haploid number.
Trophic: Of or involving the feeding habits or food relationship of different organisms in a food chain.
Trophic level: A group of organisms that occupy the same position in a food chain.
Tunicate: The subphylum of saclike filter feeders with input and output siphons.


Unintentional introduction: An introduction of nonindigenous species that occurs as a result of activities other than the purposeful or intentional introduction of the species involved. Synonyms are accidental, incidental, and inadvertent introduction.


Variable: An element, feature, or factor that is liable to vary or change.
Vector: Transportation of a species on or through a pathway via natural or human-made materials such as wind, water, shipping materials, wholesale products, cargo, equipment, people, transport vessels and vehicles, and outboard motors.
Veliger larvae: Planktonic larval stage of mollusks; precursor to the juvenile stage.
Ventral: Situated on or toward the lower, abdominal plane of the body; equivalent to the front, or anterior, in humans.
Visceral mass: Gastropods are always contained within the shell; it generally holds the bulk of the digestive, reproductive, excretory, and respiratory systems. A significant part of the visceral mass consists of the mantle, or pallial, cavity.



Watershed: The region draining into a river, river system, or other body of water.
Weed: Plant possessing a high rate of dispersal, occurring opportunistically on land or water altered by human activity and competing for resources with cultivated plants.
Wetland(s): A lowland area, such as a marsh or swamp, that is saturated with moisture. Wetlands are valued for the natural wildlife habitat and ecosystem services they provide.
Whorl: A pattern of spirals or concentric circles.


Zooplankton: Animal constituent of plankton; mainly small crustaceans and fish larvae (nonphotosynthetic).