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ABUNDANCE: The quantity of a species relative to other species in the same estuary

ADDUCTOR MUSCLE: A muscle that pulls a part of the body toward the median axis of the body. In bivalve molluscs, this muscle is used to close the shell halves and hold them together

ALGAE: A collective, or general name, applied to a number of primarily aquatic, photosynthetic groups (taxa) of plants and plant-like protists. They range in size from single cells to large, multicellular forms like the giant kelps. They are the food base for almost all marine animals. Important taxa are the dinoflagellates (division Pyrrophyta), diatoms (div. Chrysophyta), green algae (div. Chlorophyta), brown algae (div. Phaeophyta), and red algae (div. Rhodophyta). Cyanobacteria are often called blue-green algae, although blue-green bacteria is a preferable term.

AMPHIPODA: An order of laterally compressed crustaceans with thoracic gills, no carapace, and similar body segments. Although most are <1 cm long, they are an important component of zooplankton and benthic invertebrate communities. A few species are parasitic.

ANADROMOUS: Life cycle where an organism spends most of its life in the sea and migrates to freshwater to spawn. Compare to CATADROMOUS.

ANNUAL: Recurring, done, or performed every year. See SUBANNUAL and SUPRAANNUAL.

ANTHROPOGENIC: Refers to the effects of human activities.

AREAL: Refers to a measure of area.

ARTIFICIAL REEF: Natural rock or shell, construction debris, or other material placed on intertidal of subtidal bottoms, near the surface, or in mid-water, for the purposes of aggregating nearby fishes and invertebrates and increasing their production by providing additional structural habitat and feeding area.

ASCIDIAN: A tunicate (class Ascidiacea) that has a generalized sac-like, cellulose body and is usually attached to the substratum.

BATCH SPAWN: Discontinuous episodes of spawning, either of gametes or offspring. Individuals or populations that release gametes or offspring with greater continuity are serial or sequential spawners.

BATHYAL: The zone of ocean bottom at depths of 200 to 4000 m, primarily on the continental slope and rise.

BATHYBENTHAL: Associated with bottom habitat of the continental slope, or in water depths between 600 to 6000 ft (180 to 1830 m).

BATHYMETRIC: A depth measurement. Also refers to a migration from waters of one depth to another.

BENTHIC: Pertaining to the bottom of an ocean, lake, or river. Also refers to sessile and crawling animals which reside in or on the bottom.

BIGHT: An inward bend or bow in the coastline.

BIOMASS: The total mass of living tissues (wet or dried) of an organism or collection of organisms of a species or trophic level, from a defined area or volume.

BIVALVIA: Bilaterally symmetrical molluscs (also referred to as Pelecypoda) that have two lateral calcareous shells (valves) connected by a hinge ligament. They are mostly sedentary filter feeders. This class includes clams, oysters, scallops, and mussels.

BRANCHIAL: A structure or location on an organism associated with the gills.

BROADCAST SPAWNER: Planktonic release of floating or sinking (demersal) gametes (eggs, sperm) or of offspring. May be continuous or periodic in duration. See BATCH SPAWN.

BRYOZOA: Minute, moss-like colonial animals of the phylum Bryozoa.

BYSSAL THREAD: A tuft of filament, chemically similar to silk, that attaches certain molluscs to substrates.

CALCAREOUS: Composed of calcium or calcium carbonate.

CARNIVORE: An animal that feeds on the flesh of other animals. See PARASITISM.

CATADROMOUS: Life history pattern in which an organism spends most of its life in freshwater and migrates to the seas to spawn. Compare to ANADROMOUS.

CESTODE: A parasitic, ribbon-like worm having no intestinal canal(e.g., tapeworms); class Cestoda.

CHEMOTAXIS: A response movement by an animal either toward or away form a specific chemical stimulus.

CHORDATA: A phylum of animals which includes the subphyla Vertebrata, Cephalochordata, and Urochordata. At some stage of their life cycles, these organisms have pharyngeal gill slits, a notochord, and a dorsal, hollow nerve cord.

CILIA: Hair-like processes of certain cells, often capable of rhythmic beating that can produce locomotion or facilitate the movement of fluids.

CIRRI: Flexible, thread-like tentacles or appendages of certain organisms.

CLINE: A series of differing physical characteristics within a species or population, reflecting gradients or changes in the environment (e.g., body size or color).

COASTAL PLAIN RIVER: Streams deriving most of their flow form runoff of freshwater from the Florida peninsula or coastal plain of the southeastern United States, usually discharging to the Gulf of Mexico or Atlantic Ocean. Compare to SPRING RUN and PIEDMONT RIVER.

COLONY: A group of organisms living in close proximity. An invertebrate colony is a close association of individuals of a species which are often mutually dependent and in physical contact with each other. A vertebrate colony is usually a group of individuals brought together for breeding and rearing young.

COMMENSALISM: a relationship between two species, where one species benefits without adversely affecting the other.

COMMERCIAL VALUE: Economic attribute of marketable fishes, invertebrates, or other marine resources, the harvest, culture, processing, or distribution of which occurs with sufficient financial return to support a specialized, expert, and usually regulated trade.

COMMUNITY: A group of plants and animals living in a specific region under relatively similar conditions. Further restrictions are often used, such as the algal community, the invertebrate community, the benthic community, etc.

COMPETITION: Two types exist - interspecific and intraspecific. Interspecific competition exists when two or more species use one or more limited resources such as food, attachment sites, protective cover, or dissolved ions. Intraspecific competition exists when individuals of a single species compete for limited resources needed for survival and reproduction. This form of competition includes the same resources involved in interspecific competition as well as mates and territories. It is generally more intense than interspecific competition because resource needs are essentially identical among conspecifics. See NICHE.

CONGENER: Referring to members of the same genus.

CONTINENTAL SHELF: The submerged continental land mass, not usually deeper that 200 m. The shelf may extend from a few miles off the coastline to several hundred miles.

CONTINENTAL SLOPE: The steeply sloping seabed that connects the continental shelf and continental rise.

COPEPODA: A subclass of crustaceans with about species, including several specialized parasitic orders. The free-living species are small (one to several mm) and have cylindrical bodies, one median eye, and two long antennae. One order is planktonic (Calanoida), one is benthic (Harpacticoida), and one has both planktonic and benthic species (Cyclopoida). In most species, the head appendages form a complex apparatus used to sweep in and possibly filter prey (especially algae). Thoracic appendages are used for swimming or crawling on the bottom. One of the most abundant group of animals on earth, they are a major link in aquatic food webs.

CORAL: Stony or soft members in the Class Anthozoa, Phylum Cnidaria, living as solitary individuals or colonies. Stony corals have calcium carbonate skeleton and harbor symbiotic zooxanthellae, and in warm, shallow oceans grow to form massive reefs. Reefs form a unique benthic environment and harbor a diverse marine biota.

CREPUSCULAR: Relates to animals whose peak activity is during the twilight hours of dawn and dusk.

CRUSTACEA: A large class of over 26,000 species of mostly aquatic arthropods having five pairs of head appendages, including laterally opposed jaw-like mandibles and two pairs of antennae. Most have well-developed compound eyes and variously modified two-branched body appendages. The body segments are often differentiated into a thorax and an abdomen. Some common members are crabs, shrimp, lobsters, copepods, amphipods, isopods, and barnacles.

CTENIDIA: The comblike respiratory apparatus of molluscs.

CTENOPHORA: A phylum of mostly marine animals that have oval, jellylike bodies bearing eight rows of comb-like plates that aid swimming (e.g. ctenophores and comb jellies).

DECOMPOSERS: Bacteria and fungi that break down dead organisms of all types to simple molecules and ions.

DEMERSAL: Refers to swimming animals that live near the bottom of an ocean, river, or lake. Often refers to eggs that are denser than water and sink to the bottom after being laid.

DEPOSIT FEEDER: An animal that ingests small organisms, organic particles, and detritus from soft sediments, or filters organisms and detritus from such substrates.

DESICCATE: To dry completely.

DETRITIVORE: An organism that eats small fragments of partially decomposed organic material (detritus) and its associated microflora. See DECOMPOSER.

DETRITUS: Particulate organic matter produced by the decomposition of plants in riverine and coastal forests and marches, estuaries, and coastal waters. Filter-feeding and deposit-feeding organisms ingest detrital particles, the nutritional value of which is enhanced by associated fungi, bacteria, and protozoans. Together with benthic and planktonic microalgae, detritus constitutes an important base for estuarine and marine food chains.

DIATOMS: Single-celled protistan algae of the class Bacillariophyceae that have intricate siliceous shells composed of two halves. They range in size from about 10 to 200 microns. Diatoms sometimes remain attached after cellular divisions, forming chains or colonies. These are the most numerous and important group of phytoplankters in the oceans, and form the primary food base for marine ecosystems.

DIEL: Refers to a 24-hour activity cycle based on daily periods of light and dark.

DIMORPHISM: A condition where a population has two distinct physical forms (morphs). In sexual dimorphism, secondary sexual characteristics are markedly different (e.g., color or behavior).

DINOFLAGELLATE: A planktonic, photosynthetic, unicellular alga that typically has two flagellae, one being in a groove around the cell and the other extending from the center of the cell.

DIRECT DEVELOPMENT: See EMBRYONIC DEVELOPMENT

DISPERSAL: The spreading of individuals throughout suitable habitat within or outside the population range. In a more restricted sense, the movement of young animals away from their point origin to locations where they will live at maturity.

DISSOCHONCH: The adult shell secreted by newly-settled clam larvae or plantigrades.

DISTRIBUTION: (1) A species distribution is the spatial pattern of its population or populations over its geographic range. See RANGE. (2) A population depth distribution is the proportion or number of all individuals, or those of various sizes or ages, at different depth strata. (3) A population age distribution is the proportions of individuals in various age classes. (4) Within a population, individuals may be distributed evenly, randomly, or in groups throughout suitable habitat.

DIURNAL: Refers to daylight activities, or organisms most active during daylight. See DIEL.

ECHINODERMATA: A phylum of radially-symmetrical marine animals, possessing a water vascular system, and a hard, spiny skeleton (e.g., sea stars, sea urchins, and sand dollars).

ECTOPARASITE: A parasite that attacks (and usually attaches to) a host animal or plant on the outside. Feeding periods and/or attachment time may be brief compared to internal (endo) parasites.

EELGRASS: Vascular flowering plants of the genus Zostera that are adapted to living under water while rooted in shallow sediments of bays and estuaries.

EMBRYONIC DEVELOPMENT: The increase on cell number, body size, and complexity of organ systems as an individual develops from a fertilized egg until hatching or birth. In direct development, individuals at birth or hatching are essentially miniatures of the adults. In indirect development, newly hatched individuals differ greatly from the adult, and go through periodic, major morphological changes (larval stages and metamorphosis) before becoming a juvenile.

EMIGRATION: A movement out of an area by members of a population. See IMMIGRATION.

ENDEMIC: Refers to a species or taxonomic group that is native to a particular geographical region.

EPIBENTHIC: Located on the bottom, as opposed to in the bottom.

EPIDERMAL: Refers to an animal=s surface or outer layer of skin.

EPIFAUNA: Animals living on the surface of the bottom.

EPIPELAGIC: The upper sunlit zone of oceanic water where phytoplankton live and organic production takes place (approximately the top 200 m). See EUPHOTIC.

EPIPHYTIC: Refers to organisms which live on the surface of a plant (e.g., mosses growing on trees).

EPIPODAL: A structure or location associated with the leg or foot; typically refers to arthropod anatomy.

ESCARPMENT: A steep slope in topography, as in a cliff or along the continental slope.

ESTUARY: A semi-enclosed body of water with an open connection to the sea. Typically there is a mixing of sea and fresh water, and the influx of nutrients from both sources results in high productivity.

EUHALINE: Water with salt concentrations of 30C40 ppt.

EUPHOTIC: Refers to the upper surface zone of a water body where light penetrates and phytoplankton (algae) carry out photosynthesis. See EPIPELAGIC.

EURYHALINE: Refers to an organism that is tolerant of a wide range of salinities.

EURYTHERMAL: Refers to an organism that is tolerant of a wide range of temperatures.

EXOTIC SPECIES: Opportunistic organisms, usually plants or animals larger than diseases or parasites, that are not native to an area and detract from the ecological value or beneficial uses of natural resources, by virtue of their number, growth form, behavior, or other biological attribute. Also call nuisance species, weeds, or pests.

EXTANT: Existing or living at the present time; not extinct.

EXTIRPATED: Locally eliminated.

FAUNA: All of the animal species in a specified region.

FECUNDITY: The potential of an organism to produce offspring (measured as the number of gametes). See REPRODUCTIVE POTENTIAL.

FILTER FEEDER: Any organism that filters small animals, plants, and detritus from water or fine sediments for food. Organs used for filtering include gills in clams and oysters, baleen in whales, and specialized appendages in crustaceans and marine worms.

FINGERLING: Refers to a small juvenile fish (often a salmonid) that is about 100 mm long.

FLAGELLATE: Refers to cells that have motility organelles or microorganisms that possess one or more flagellum used for locomotion.

FLOATING VEGETATION: Living plants which inhabit the water surface for all or part of their life cycle. Mostly vascular plants but including such algae as Sargassum. Compare to SAV (SUBMERGED AQUATIC VEGETATION).

FLORA: All of the plant species in a specified region.

FOOD WEB (CHAIN): The feeding relationships of several to many species within a community in a given area during a particular time period. Two broad types are recognized: 1) grazing webs involving producers (e.g., algae), herbivores (e.g., copepods), and various combinations of carnivores and omnivores, and (2) detritus webs involving scavengers, detritivores, and decomposers that feed on the dead remains of organisms from the grazing webs, as well as on their own dead. A food chain refers to organisms on different trophic levels, while a food web refers to a network of interconnected food chains. See TROPHIC LEVEL.

FORAGE FISH: Species occurring in large numbers and comprising a significant prey-base for predatory fishes.

FOULING: Occurs when large numbers of plants or animals attach and grow on various structures (floats, pipes, and pilings), often interfering with their use. Fouling organisms include barnacles, mussels, bryozoans, and sponges.

FRESH WATER: Water that has a salt concentration of 0.0C0.5 ppt.

FRY: Very young fish. For trout and salmon, they are young that have just emerged from the gravel and are actively feeding.

GAMETE: A reproductive cell. When two gametes unite they form an embryonic cell (zygote).

GASTROPODA: The largest class of the Phylum Mollusca. This group includes terrestrial snails and slugs as well as aquatic species such as whelks, turbans, limpets, conchs, abalones, and nudibranchs. Most have external shells that are often spiraled (lost or is reduced in some), and move on a flat, undulating foot. They are mostly herbivorous and scrape food with a radula, an organ analogous to a tongue.

GONOCHORISTIC: The condition in a species in which the male and female sexes are spearate and genetically fixed. A gonochoristic organism, during its life cycle has, testes or ovaries and functions only as female or male.

GROUNDFISH: Fish species that live on or near the bottom, often called bottomfish.

GYRE: An ocean current that follows a circular or spiral path around an ocean basin, clockwise in the northern hemisphere and counterclockwise in the southern hemisphere.

HABITAT: The particular type of place where an organism lives within a more extensive area or range. The habitat is characterized by its biological components and/or physical features (e.g., sandy bottom of the littoral zone or on kelp blades within 10 m of the water surface).

HAPLOSPORIDIAN: A unicellular protozoan occurring in vertebrate and invertebrate hosts, often causing disease.

HATCHERY STOCKED: Distinguished from naturally-occurring recruits in a population, these animals are raised in captivity for the purposes of release into natural habitats or direct harvest.

HERBIVORE: An animal that feeds on plants (phytoplankton, large algae, or higher plants).

HERMAPHRODITE: Refers to an organism having both male and female sex organs on the same individual. Self-fertilization is possible because the ovarian and testicular components of its gonads mature simultaneously. Simultaneous hermaphrodite is a synonym. See PROTANDROUS HERMAPHRODITE, PROTOGYNOUS HERMAPHRODITE, and SEQUENTIAL HERMAPHRODITE.

HYDROZOA: A class of the phylum Cnidaria. The primary life stage is non-motile and has a sac-like body composed of two layers of cells and a mouth that opens directly into the body cavity. A second life stage, the free-living medusa, often resembles the common jellyfish.

HYPERSALINE (HYPERHALINE): Water with a salt concentration over 40 ppt.

HYPOLIMNION: The cold bottom water zone of a lake below the thermocline.

IMMIGRATION: A movement of individuals into a new population or region. See EMIGRATION, MIGRATION, and RECRUITMENT.

INCIDENTAL CATCH: Catch of a species that was not the focus of a fishery, but taken along with the species being sought.

INDICATOR OF STRESS: Species whose presence or absence in an environment has been documented as being correlated with polluted or unpolluted conditions, or ecological stress of other forms. Species that occur in or dominate polluted areas, such as the polychaete worm, Capitella capitata, are called pollution indicators.

INDIRECT DEVELOPMENT: See EMBRYONIC DEVELOPMENT

INFAUNA: Animals living in bottom substrates, underneath the bottom surface.

INNER SHELF: The continental shelf extending from the mean low tide line to a depth of 20 m.

INSTAR: The intermolt stage of young arthropods.

INSULAR: Of or pertaining to an island or its characteristics (i.e., isolated).

INTERTIDAL: The ocean or estuarine shore zone exposed between high and low tides.

ISOBATH: A contour mapping line that indicates a specified constant depth.

ISOPODA: An order of about 4000 species of dorsoventrally compressed crustaceans that have abdominal gills and similar abdominal and thoracic segments. Terrestrial pillbugs and thousands of benthic marine species are included. Most species are scavengers and/or omnivores; a few are parasitic.

ISOTHERM: A contour line connecting points of equal mean temperature for a given sampling period.

ITEROPAROUS: Refers to an organism that reproduces several times during its lifespan (i.e., does not die after spawning).

KEYSTONE SPECIES: A species whose presence, even in relatively small numbers, exerts profound influence over the structure or functioning of a community. The influence, often through regulation of other species= population sizes or energy flow, tends to be stabilizing and contributes to the maintenance of the community=s distinctive characteristics.

KINESIS: A randomly directed movement by an animal in response to a sensory stimulus such as light, heat, or touch. When the response is directed, it is called a taxis. See CHEMOTAXIS.

LACUSTRINE: Pertaining to, or living in, lakes or ponds.

LAGOON: A shallow pond or channel linked to the ocean, but often separated by a reef or sandbar.

LARVAE: An early developmental stage of an organism that is morphologically different from the juvenile or adult form. See EMBRYONIC DEVELOPMENT.

LATERAL LINE: A pressure sensory system located in a line of pores under the skin on both sides of most fishes. The system is connected indirectly with the inner ear and senses water pressure changes due to water movement (including sound waves).

LICENSED SPECIES: Habitats, harvest, possession, sale, disposition, consumption, or other use of plants and animals which requires a license or permit issued by federal, state, or local government.

LIMNETIC: Pertaining to the open, deeper water of lakes or ponds bounded by the zone of emergent vegetation.

LISTED SPECIES: Plants or animals, or their habitats, determined by the U.S. Fish and Wildlife Service, state wildlife agency, or other authoritative source to be rare, threatened, endangered, or of uncertain status, but for which concern may exist for other reasons. Species or habitats under study for classification or re-classification under these systems may also be recognized as listed, under special circumstances. Also called species at risk.

LITTORAL: The shore area between the mean low and high tide levels. Water zones in this area include the littoral pelagic zone and the littoral benthic zone.

LIVE BOTTOM: Marine or estuarine benthic environments dominated by sponges, tunicates, soft corals, solitary and ahermatypic stony corals, coralline and soft algae, and other species, usually colonial form. This type of live bottom is often associated with hard substrata such as rock or shell, and supports a range of gastropods, bivalves, crustaceans, echinoderms, and fishes.

MACROALGAE: Relatively large, multicellular, non-vascular marine or estuarine plants that float (some species of Sargassum); drift along the bottom, unattached (Ulva); or have hold-fasts that anchor the plant to sand, rock, or shell (Caulerpa). Different than planktonic or benthic unicellular (micro-) algae.

MANTLE: The upper fold of skin in molluscs that encloses the gills and most of the body in a cavity above the muscular foot. In squids and allies, the mantle is below the body and behind the tentacles (derived from the foot) due to the shift in the dorsal-ventral axis. The mantle produces the shell in species having them.

MANGROVE: Evergreen shrubs or trees growing in the intertidal zone of tropical and subtropical oceans, with morphological, physiological, or reproductive adaptations to periodic flooding and salt-water. Stands of mangrove trees are called forests or mangals. The largest and most diverse assemblage of North American mangroves occurs on the Florida peninsula. Mangroves provide unique structural habitat and their high rate of productivity delivers large amounts of organic detritus to shallow waters. Their productivity and usual proximity to water of low salinity make mangrove forests important nursery areas for many estuarine and marine animal species.

MARSH: Collections of annual and perennial grasses, sedges, ferns, and other non-woody vascular plants growing in areas of wet land, either tidal or non-tidal in nature. Tidal marsh is the temperate-zone ecological analogue of tropical mangrove forests. Tidal marsh may be estuarine or freshwater. Non-tidal marsh occurs in rivers, lakes, and wet prairies. Marshes are a unique habitat type and support a large variety and number of wildlife.

MEAN LOWER LOW WATER (MLLW): The arithmetic mean of the lower low water heights of a mixed tide over a specific 19-year Metonic cycle (the National Tidal Datum Epoch). Only the lower low water of each tidal day is included in the mean.

MEGALOPAE: The larval stage of a crab characterized by an adult-like abdomen, thoracic appendages, and a developed carapace.

MEIOFAUNA: Very small animals, usually <0.5 mm in diameter. Microscopic and smal macroscopic metazoan fauna inhabiting the surface of the sea bottom (e.g., nematodes, kinorhynchs, ostracods, copepods, halacarids, turbelliarians, gastrotrichs, oligochaetes)

MERISTIC: Refers to countable measurements of segments or features such as vertebrae, fin rays, and scale rows. Counts of these are used in population comparisons and classifications.

MESOHALINE: Water with a salt concentration of 5C18 ppt.

METAMORPHOSIS: Process of transforming from one body from to another form during development (e.g., tadpole changing to a frog). See EMBRYONIC DEVELOPMENT.

METRIC TON (t): A unit of mass or weight equal to 2204.6 lb.

MIGRATION: Movement by a population or subpopulation from one location to another (often periodic or seasonal, and over long distances). Vertical migrations in the water column may be daily or seasonal within the same area. Migrations between deep and shallow areas are usually seasonal and related to breeding. Many marine birds and mammals have seasonal latitudinal migrations associated with breeding. See EMIGRATION, IMMIGRATION, RANGE, and RECRUITMENT.

MILT: The seminal fluid and sperm of male fish.

MOBILITY: Capable of moving or being moved from place to place.

MOLT: The process of shedding and regrowing an outer skeleton or covering at periodic intervals. Crustaceans and other arthropods molt their exoskeletons, grow rapidly, and produce larger exoskeletons. Most reptiles, birds, and mammals molt skin, feathers, and fur, respectively.

MONOGAMOUS: Having one mate in a breeding season.

MORPHOLOGY: The appearance, form, and structure of an organism.

MORPHOMETRICS: The study of comparative morphological measurements.

MORTALITY: Death rate expressed as a proportion of a population or community of organisms. Mortality is caused by a variety of sources, including predation, disease, environmental conditions, etc.

MOTILE: Capable of or exhibiting movement or locomotion.

MUTUALISM: An interaction between two species where both benefit. Some authorities consider true mutualism to be obligatory for both species, while mutually beneficial relationships that are not essential for either species are classified as protocooperative (e.g., the blacksmith cleaning fish eating external parasites from sea basses).

NACREOUS MATERIAL: A calcareous, lustrous secretion in the inner surface of the shell of many molluscs. Foreign particles lodging between the inner shell surface and mantle are covered by nacre, often forming pearls.

NANOPLANKTON: Microscopic, planktonic organisms smaller than 20 microns in diameter.

NATAL: Pertaining to birth and hatching.

NEKTONIC: Refers to pelagic animals that are strong swimmers, live above the substrate in the water column, and can move independently of currents.

NEMERTEA: A phylum of unsegmented, elongated marine worms having a protusible proboscis and no body cavity, and live mostly in coastal mud or sand; nemerteans.

NERITIC: An oceanic zone extending from the mean low tide level to the edge of the continental shelf. See INNER SHELF, LITTORAL, and OCEANIC ZONES.

NEUSTON: Organisms that live on or just under the water surface, often dependent on surface tension for support.

NICHE: The fundamental niche is the full range of abiotic and biotic factors under which a species can live and reproduce. The realized niche is the set of actual conditions under which a species or a population of a species exists, and is largely determined by interactions with other species.

NOCTURNAL: Refers to night, or animals that are active during night.

OCEANIC: Living in or produced by the ocean.

OCEANIC ZONE: Pelagic waters of the open ocean beyond the continental shelf. See BATHYPELAGIC, EPIPELAGIC, ABYSSOPELAGIC, MESOPELAGIC, and NERITIC.

OLIGOHALINE: Water with a salt concentration of 0.5C5.0 ppt.

OMNIVORE: An animal that eats both plants and animals.

OOCYTES: The cells in ovaries that will mature into eggs.

OTOLITHS: Small calcareous nodules located in the inner ear of fishes used for sound reception and equilibration. They are often used by biologists to assess daily or seasonal growth increments.

OUT-MIGRATION: Movement of animals out of or away from an area (e.g., juvenile salmonids moving from rivers to the ocean).

OVIGEROUS: The condition of being ready to release mature eggs; egg-bearing.

OVIPAROUS: Refers to animals that produce eggs that are laid and hatch externally. See OVOVIVIPAROUS and VIVIPAROUS.

OVIPOSITION: The process of placing eggs on or in specific places, as opposed to randomly dropping or broadcasting them.

OVOVIVIPAROUS: Refers to animals whose eggs are fertilized, developed, and hatched inside the female, but receive no nourishment form her. See OVIPAROUS and VIVIPAROUS.

PALP: An organ attached to the head appendages of various invertebrates; usually associated with feeding functions.

PALUSTRINE: Pertaining to, or living in or near, a river or flowing stream.

PARASITISM: An obligatory association where one species (parasite) feeds on, or uses the metabolic mechanisms of the second (host). Unlike predators, parasites usually do not kill their hosts, although hosts may later die form secondary causes that are related to a weakened condition produced by the parasite. Parasitism may also be fatal when high parasite densities develop on or in the host.

PARTURITION: The act of giving birth. See SPAWN.

PATHOGEN: A microorganism or virus that produces disease and can cause death.

PEDIVELIGER: The larval stage of bivalves during which a functional pedal (footlike) organ develops.

PELAGIC: Pertaining to the water column, or to organisms that live in the water column.

PELAGIVORE: A carnivore that feeds in the water column.

PHYLOGENY: Refers to evolutionary relationships and lines of descent.

PHYTOPLANKTON: Microscopic plants and plant-like protists (algae) of the epipelagic and neritic zones that are the base of offshore food webs. They drift with currents, but usually have some ability to control their level in the water column. See ALGAE and DIATOMS.

PIEDMONT RIVER: Rivers originating inland and upland of the coastal plains, for which discharges are affected by snow-melt or runoff from catchments other than their respective coastal drainage areas. Alluvial in nature, these rivers are very much larger than coastal plain rivers or spring runs. Example: Apalachicola River.

PISCIVOROUS: Refers to a carnivorous animal that eats fish.

PLANKTIVOROUS: Refers to an animal that eats phytoplankton and/or zooplankton.

PLANKTON: See PHYTOPLANKTON and ZOOPLANKTON.

PLANTIGRADE: A young, newly settled post-larval clam.

PLEOPODS: Paired swimming appendages on the abdomen of crustaceans.

POLYCHAETA: A class of segmented, mostly marine, annelid worms that bear bristles and fleshy appendages on most segments.

POLYGAMOUS: Having more than one mate at a time or in a breeding season. In botony, having both hermaphroditic and unisexual flowers on the same plant or on different plants of the same species.

POLYHALINE: Water with a salt concentration between 18C30 ppt.

POPULATION: All individuals of the same species occupying a defined area during a given time. Environmental barriers may divide the population into local breeding units (demes) with restricted immigration and interbreeding between the localized units. See SPECIES, SUSPECIES, and SUBPOPULATION.

PREDATION: An interspecific interaction where one animal species (predator) feeds on another animal or plant species (prey) while the prey is alive or after killing it. The relationship tends to be positive (increasing) for the predator population and negative (decreasing) for the prey population. See PARASITISM, SYMBIOTIC, CARNIVORE, and TROPHIC LEVEL.

PRODUCTION: Gross primary production is the amount of light energy converted to chemical energy in the form of organic compounds by autotrophs like algae. The amount left after respiration is net primary production and is usually expressed as biomass or calories/unit area/unit time. Net production for herbivores and carnivores is based on the same concept, except that chemical energy from food, not light, is used and partially stored for life processes. Efficiency of energy transfers between trophic levels ranges from 10C65% (depending on the organism and trophic level). Organisms at high trophic levels have only a fraction of the energy available to them that was stored in plant biomass. After respiration loss, net production goes into growth and reproduction, and some is passed to the next trophic level. See FOOD WEB and TROPHIC LEVEL.

PROKARYOTIC: Organisms that have nuclear bodies, but lack chromosomes, nucleoli, and nuclear membranes.

PROTANDROUS HERMAPHRODITE: An organism which sexually matures first as a male and through sequential hermaphroditism (synonyms: sex change, sex reversal, sex inversion) becomes a sexually mature female. This final condition, named the terminal phase, is usually irreversible. Common for some species of shrimp. See HERMAHRODITE, PROTOGYNOUS HERMAPHRODITE, and SEQUENTIAL HERMAPHRODITE.

PROTISTAN: Pertaining to the eukaryotic unicellular organisms of the kingdom Protista, including such groups as algae, fungi, and protozoans.

PROTOGYNOUS HERMAPHRODITE: An organism which sexually matures first as a female and through sequential hermaphroditism (synonyms: sex change, sex reversal, sex inversion) becomes a sexually mature male. This final condition, named the terminal phase, is usually irreversible. See HERMAHRODITE, PROTANDROUS HERMAPHRODITE, and SEQUENTIAL HERMAPHRODITE

PROTOZOA: A varied group of either free-living or parasitic unicellular flagellate and amoeboid organisms.

PYCNOCLINE: A zone of marked water density gradient that is usually associated with depth.

QUARTZITIC: Of or pertaining to quartz (crystalline silicon dioxide, SiO2), found worldwide as a component of granite and sandstone, and comprising a major sediment type in the southeastern United States. Also quartziferous.

RACE: An intraspecific group of subpopulation characterized by a distinctive combination of physiological, biological, geographical, or ecological traits.

RADULA: a toothed belt or tongue in the buccal cavity of most molluscs that is used to scrape food particles from a surface, or modified otherwise to serve a variety of feeding habits.

RANGE: (1) The geographic range is the entire area where a species is known to occur or to have occurred (historical range). The range of a species may be continuous, or it may have unoccupied gaps between populations (discontinuous distribution). (2) Some populations, or the entire species, may have different seasonal ranges. These may be overlapping, or they may be widely separated with intervening ares that are at most briefly occupied during passage on relatively narrow migration routes. (3) Home range refers to the local area that an individual or group uses for a long period or life. See DISTRIBUTION and TERRITORY.

RECREATIONAL VALUE: Economic and social attribute of fishes and invertebrates sought by individual persons as leisure activity. Some species with commercial value also have recreational value. Recreational fishing supports a large supply and service industry, but is governed by regulations that are separate from those established for commercial harvest.

RECRUITMENT: The addition of new members to a population or stock through successful reproduction or immigration.

RED TIDE: A reddish coloration of sea waters caused by a large bloom of red flagellates. The accumulation of metabolic by-products from these organisms is toxic to fish and many other marine species. The accumulation of these metabolites in shellfish makes shellfish toxic to humans.

REGULATED SPECIES: Includes listed species, species of commercial or recreational value, some indicators of stress, licensed species, and keystone species. Also includes species in parks, preserves, or other management areas, for which leisure observation or scientific study is regulated by an agency of government. Access to, or use of, a regulated species is specified by law or rule.

REPRODUCTIVE POTENTIAL: The total number of offspring possible for a female of a given species to produce if she lives to the maximum reproductive age. This is found by multiplying the number of possible reproductive periods by the average number of eggs or offspring produced by females of each age class. This potential is seldom realized, but this and the age of first reproduction , or generation time, determine the maximum rate of population increase under ideal conditions.

RHEOTAXIS: A response movement by an animal toward or away from stimulation by a water current.

RIVERINE: Pertaining to a river or formed by a river or stream.

ROE: The egg-laden ovary of fish, or the egg mass of certain crustaceans.

RUN: A group of migrating fish (e.g, salmon run).

SABELLARIID REEF: Collections of cemented sandy tubes formed by polychaete worms of the Family Sabellariidae. A distinct epibenthic environment inhabited by numerous crevice-dwelling and burrowing organisms. Common in shallow water of southeastern Florida.

SALT WEDGE: A wedge-shaped layer of salt water that intrudes upstream beneath a low-density freshwater lens that has thinned while flowing seaward.

SAV (SUBMERGED AQUATIC VEGETATION): Marine and estuarine vascular plants which generally grow in shallow, protected coastal waters on muddy sand bottoms, or freshwater vascular plants that grow in rivers, spring runs, and lakes. SAV have morphological, physiological, and reproductive adaptations to immersion, salt water, periods of exposure to air, light limitations, or herbivory. In tidal waters, SAV are called seagrasses. Seagrass beds create a unique benthic environment and their productivity contributes to the maintenance of sport and commercial fisheries, and of population of some listed species.

SCAVENGER: Any animal that feeds on dead animals and remains of animals killed by predators. See DECOMPOSER and DETRITIVORE.

SEAMOUNT: An undersea mountain rising more than 3000 ft (914 m) from the sea floor, but having a summit at least 1000 ft (305 m) below sea level (in contrast to an island).

SEDENTARY: Refers to animals that are attached to substrate or confined to a very restricted area (or those that do not move or move very little). See SESSILE.

SEDIMENT SIZE: Grades of material that settle to the bottom or are moved along it by geophysical forces; silt/clay is smaller than 0.0625 millimeters (mm) in size; very fine and fine sand are larger than silt/clay but smaller that 0.25 mm; medium to very coarse sand is even larger but smaller than 2.0 mm; and gravel is larger than 2.0 mm.

SEMELPAROUS: Animals that have a single reproductive period during their lifespan.

SEQUENTIAL HERMAPHRODITE: An organism in which, for a brief transitional stage of its life cycle, both male and female sex functions are present. Self-fertilization has not been observed. See HERMAPHRODITE, PROTANDROUS HERMAPHRODITE, and PROTOGYNOUS HERMAPHRODITE.

SESSILE: Refers to an organism that is permanently attached to the substrate. See SEDENTARY.

SETTLEMENT: The act of or state of making a permanent residency. Often refers to the period when fish and invertebrate larvae change from a planktonic to a benthic existence.

SHELL: Calcified exoskeleton of gastropods and bivalves. Whole and broken shell may accumulate as the residue under living oyster reefs, or in some settings form the principal bottom material in estuaries, inlets, or shallow shelf areas. Weathered shell creates calcium carbonate (CaCO3) sediment and beach sand. Also used in connection with serpulid reef and vermitid reef material.

SHOAL: (1) A sand bar in a body of water that is exposed at low tide. (2) An area of shallow water. (3) A group of fish (school). (4) As a verb, to collect in a crowd or school.

SIPHONS: The 'necks' or tubes of clams and other bivalves that carry water containing food and oxygen into the gills, and then expels water containing waste products (exhalent siphon).

SLOUGH: A shallow inlet or backwater whose bottom may be exposed at low tide. Sloughs often border estuaries and typically have a stream passing through them.

SPAT: Juvenile bivalve molluscs which have settled from the water column to the substrate to begin a benthic existence.

SPAWN: The release of eggs and sperm during mating. Also, the bearing of offspring by species with internal fertilization. See PARTURITION.

SPECIES: (1) A fundamental taxonomic group ranking after a genus. (2) A group of organisms recognized as distinct from other groups, whose members can interbreed and produce fertile offspring. See POPULATION, SUBPOPULATION, and SUBSPECIES.

SPERMATOPHORE: A capsule or gelatinous packet (extruded by a male) containing sperm and used to transfer sperm to females. Spermatophores are produced by certain invertebrates and some primitive vertebrates.

SPIROCHETE: A spiral-shaped, non-flagellated bacterium of the order Spirochaetales. This group can be free-living or parasitic. Some members cause diseases.

SPIT: A long, narrow sand bar or peninsula extending into a body of water which is at least partly connected to the shore. See SHOAL.

SPOROCYST: A simple larval stage of parasitic trematode worms. Contact with host causes a metamorphosis from an earlier stage to this stage.

SPRING RUN: The surface outlet of a spring, which in many cases flows directly to the sea or to a river. Ground water comprises more of the discharge of a spring run that does surface-water runoff. Spring runs of Florida are characterized by water of stable temperature, highly dissolved solids, and high transparency.

STENOHALINE: Pertaining to organisms that are restricted to a narrow range of salinities, in contrast to EURYHALINE.

STIPE: A thickened, stalk-like structure in algae that bears other structures, such as blades. Also, the basal portion of the thallus or plant body of alga.

STOCK: A related group or subpopulation. See POPULATION and SUBPOPULATION.

SUBADULTS: Maturing individuals that are not yet sexually mature.

SUBANNUAL: Recurring, done, or performed during a time frame of less than one year.

SUBLITTORAL: The benthic zone along a coast, or lake, that extends from mean low tide to depths of about 200m.

SUBPOPULATION: A breeding unit (deme) of a larger population. These units may differ little genetically and taxonomically. See SUBSPECIES. Subpopulations may intergrade with some interbreeding, or they may occupy a common seasonal range prior to the mating season. The units may have different reproduction times and be separated spatially or temporally. See RACE, STOCK, and POPULATION.

SUBSPECIES: A taxonomic class assigned to populations and/or subpopulations when interbreeding (gene flow) between populations is limited, and there are significant differences in some combination of characteristics between subspecies (e.g., appearance, anatomy, ecology, physiology, and behavior). While successful interbreeding can occur when the groups are in contact, under natural conditions reproductive isolation is complete and the groups are considered distinct. Classification of such groups is based on the comparative study and judgement of phylogenists. A second epithet for each subspecies is added to the binomial for the species (e.g., Oncorhynchus clarki clarki). See SPECIES, POPULATION, and SUBPOPULATION.

SUBTIDAL: See SUBLITTORAL.

SUPRAANNUAL: Recurring, done, or performed during a time frame greater than one year.

SUPRALITTORAL: The splash zone of land (adjacent to the sea) that is above the mean high tide level.

SUSPENSION FEEDER: An animal that feeds directly or by filtration on minute organisms and organic debris that is suspended in the water column.

SYMBIOSIS: The co-evolved interaction between two organisms of different species that is positive, negative, or neutral in its effects on each species. See COMPETITION, MUTUALISM, PARASITISM, and PREDATION.

SYMBIONT: A participant in symbiosis.

TAXONOMY: A system of describing, naming, and classifying animals and plants into related groups based on common features (e.g., structure, embryology, and biochemistry).

TEMPERATE REGION: Oceanic waters between the 13C20OC winter isotherms.

TEMPORAL: Pertaining to time. Used to describe organism activities, developmental stages, and distributions as they relate to daily, seasonal, or geologic time periods.

TERRITORY: An area occupied and used by an individual, pair, or larger social group, and from which other individuals or groups of the species are excluded, often with the aid of auditory, olfactory, and visual signals, threat displays, and outright combat.

TEST: A rigid calcareous exoskeleton produced by some echinoderms in the class Echinoidea (e.g., sea urchins and sea dollars).

THERMOCLINE: A relatively narrow boundary layer of water where temperature decreases rapidly with depth. Little water or solute exchange occurs across the thermocline, which is maintained by solar heating of the upper water layers.

TOP PREDATOR: In a food chain or food web, the animal species which has no natural predator. The flow of trophic energy in ecological systems is said to end with top predators, which may be keystone species.

TREMATODA: A class of parasitic flatworms of the phylum Platyhelminthes. Trematodes have one or more muscular, external suckers and are also known as flukes.

TRIPLOIDY: The occurrence of three times the haploid number of chromosomes. When genetically engineered, randomly occurring traits my be selected for commercial applications. For example, the Pacific oyster experiences a degradation in flesh quality associated with spawning. Non-reproducing triploid cultures avoid this seasonal problem.

TROCHOPHORE: A molluscan larval stage (except in Cephalapoda) following gastrulation (embryonic stage characterized by the development of a simple gut). It is commonly ciliated, biconically shaped, and free-swimming; it establishes an evolutionary link between annelids and molluscs, since both groups display a similar life stage.

TROPHIC LEVEL: The feeding level in an ecosystem food chain characterized by organisms that occupy a similar functional position. At the first level are autotrophs or producers (e.g., kelps and diatoms); at the second level are herbivores (e.g., salmon and seals). Omnivores feed at the second and third levels. Decomposers and detritivores may feed at all trophic levels. See FOOD WEB and PRODUCTION.

TROPICAL REGION: Oceanic waters between the 20OC winter isotherms in the southern and northern hemispheres. Tropical neritic waters along the west coasts of North and South America extend from the southern tip of Baja California, Mexico, to about 5OS along the coast of Peru.

TURBELLARIA: A class of mostly aquatic, non-parasitic flatworms that are leaf-shaped and covered with cilia.

UPLAND RIVER: A river or large flowing stream that discharges to a lake or to another river, rather than the sea.

UPWELLING: The process whereby prevailing seasonal winds create surface currents that allow nutrient rich cold water from the ocean depths to move into the euphotic or epipelagic zone. This process breaks down the thermocline and increases primary productivity, and ultimately fish abundance.

VASCULAR: possessing vessels through which plant or animal fluids pass.

VELICONCHA: A bivalve larval stage. A veliconcha has two larval shells and moves by using its velum.

VELIGER: A ciliated larval stage common in molluscs. This stage forms after the trochophore larva and has some adult features, such as a shell and foot.

VELUM: The ciliated swimming organ of a larval mollusc.

VERMITID REEF: Cemented collections of the calcified shells formed by various worm shell species of gastropods in the Phylum Mollusca. A distinct epibenthic environment inhabited by numerous crevice-dwelling and burrowing organisms. Commonly associated with rock in shallow waters of peninsular Florida.

VIVIPAROUS: Refers to animals that produce live offspring; eggs are retained and fertilized in the female (as compared to OVIPAROUS).

WATER COLUMN: The water mass between the surface and the bottom.

WRACK: Shoreline accumulations of macroalgae, submersed aquatic vegetation, marsh or mangrove debris, and/or terrestrial plant matter. Beached flotsam.

YEAR-CLASS: Refers to animals of a species population hatched or born in the same year at about the same time; also known as a cohort. Strong year-classes result when there is high larval and juvenile survival; the reverse is true for weak year-classes. The effects of strong and weak year-classes on population size and structure may persist for years in species with long lives. Variation in year-class strength often affects fisheries. See DISTRIBUTION and STOCK.

ZOEA: An early larval stage of various marine crabs and shrimp; zoea have many appendages and long dorsal and anterior spines.

ZOOPLANKTON: Animal members of plankton. Most range in size from microscopic to about 2.54 cm in length. They reside primarily in the epipelagic zone and feed on phytoplankton and each other. Although they have only a limited ability to swim against currents, many undertake diel migrations. Taxa include protozoa, jellyfish, comb jellies, arrow-worms, lower chordates, copepods, water fleas, krill, and the larvae of many fish and invertebrates that are not planktonic as adults.

 
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