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Abiotic interactions. Interactions between an organism and physical and chemical aspects of the environment.
Abyssal plain. The deep ocean floor, an expanse of low relief at depths of 4,000 to 6,000 m
Abyssobenthic. Referring to benthic organisms living at abyssal depths.
Abyssopelagic zone. The 4,000 to 6000-m-depth zone, seaward of the shelf-slope break
Acclimation. Given a change of a single parameter, a readjustment of the physiology of an organism, reaching a new steady state
Accuracy. Is the correctness of a measure when comparing to a known standard. See also resolution and precision.
Action spectrum. Portion of the light spectrum used in photosynthesis.
Active suspension feeders. Suspension feeders that produce a current to actively entrain and capture particles.
Adaptation. An increase in fitness over time as a population evolves in response to a new environment.
Aerobic scope. The range of possible oxidative metabolism from rest to maximal exercise. See also Scope for activity.
Aerosol. A variety of substances that may seed clouds and therefore increase cloud cover.
Age structure. The relative abundance of different age classes in a population
Aggregated spatial distribution. A case where individuals in a space occur in clusters too dense to be explained by chance
Ahermatypic. Non-reef-building (referring to scleractinian corals)
Allee effect. The increase of probability of extinction when the population is so small that population density itself matters. Finding mates in a sparse population is the major mechanism of decline in such a case.
Allele. One of several variants that can occupy a locus on a chromosome
Allopatric speciation. The differentiation of geographically isolated populations into distinct species
Allozyme. A variant of an enzyme type. These may be variants of a specific enzyme (e.g., cytochrome c) that are the products of a single genetic locus.
Alternative stable states. Depending on specific circumstances or sequences of events, a community might move toward and then exist in one of two or more states that are stable for long periods of time until a major perturbation occurs.
Amensal. Negatively affecting one or several species
Amino acids. Basic structural unit of proteins
Amnesic shellfish poisoning. Uptake by shellfish of domoic acid when feeding on certain species of Pseudo-nitzschia, resulting in being poisonous for consumption by humans.
Amphidromic points. Points in the ocean that do not change in tidal height. Tidal currents tend to revolve around these points.
Anadromous fish. Fish that spends most of its life feeding in the open ocean but that migrates to spawn in fresh water
Anaerobes. Organisms that carry out metabolic processes in the absence of oxygen. See also Aerobes.
Anchor dredge. A bottom dredge used to dig into soft sediments down to a specified depth below the sediment–water interface.
Annelida. Phylum characterized by wormlike shape, segmentation, including free-living and parasitic forms, but usually benthic occurrence of free-living forms.
Anoxic. Lacking oxygen.
Anthozoa. A class of the phylum Cnidaria, including anemones, corals, and sea fans.
Antibody. A specialized protein produced in response to the introduction of a foreign molecule into the body, usually to destroy the foreign body.
Apoptosis. A form of cell death, in which a series of cellular processes determines or programs the death of the cell, usually without harming the rest of the cells in the organism.
Aposematic coloration. A conspicuous coloration borne by an organism that has evolved to signal to a predator the organism’s distastefulness or even poisonous state.
Applied marine biology. The use of marine biology to study practical problems such as pollution, or the use of biological structures to protect against wave surge.
Aragonite. An orthorhombic crystal variant of calcium carbonate that is less stable and more soluble than another variant, calcite. A common constituent of coral skeletons and many snail shells (exception: genus Conus).
Aragonite saturation horizon (ASH). Depth below which aragonite-secreting organisms cannot secrete aragonite and live.
Arbuscular mycorrhizae. Fungi that live as mutualists in association with the roots of plants.
Archaea. One of the three major domains of life, including many types of microorganisms that are known mostly from extreme environments, such as those lacking oxygen or at high temperature.
Arctic Oscillation. Temporal variability of climate involving winds circulating counterclockwise around the Arctic at around 55° N latitude.
Aristotle’s lantern. A jawlike structure found in sea urchins consisting of a complex series of mobile teeth that can scrape algae or invertebrates from a hard surface.
Arrow worms. Members of the phylum Chaetognatha, a group of planktonic carnivores
Asexual reproduction. Reproduction of the individual without the production of gametes and zygotes
Assimilation efficiency. The fraction of ingested food that is absorbed and used in metabolism
Assortative mating. The mating of a given genotype mates with another genotype at a frequency disproportionate to that expected from random encounter
Asteroidea. A class of carnivorous Echinodermata, the true starfish, having mobile arms, usually in multiples of five, and tube feet.
Atoll. A horseshoe or circular array of islands, capping a coral reef system perched around an oceanic volcanic seamount
ATP. Adenosine triphosphate, an adenosine nucleotide used universally by organisms to store and transfer energy.
Attenuation (of light). Diminution of light intensity; explained, in the ocean, in terms of absorption and scattering
Autotrophic algae. Algae capable of photosynthesis and growth using only dissolved inorganic nutrients
Auxospore. In diatoms, a cell that results from successive decreases of cell size during diatom reproduction, resulting in either production of gametes or rejuvenation of size and subsequent renewed cell division.
Auxotrophic algae. Algae requiring a few organically derived substances, such as vitamins, along with dissolved inorganic nutrients for photosynthesis
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Bacteria. One of the three major domains of life, including many bacterial groups that decompose organic matter, transmit disease, or may photosynthesize.
Ballast water. Water used as ballast in large ships.
Bar. A linear raised area of bottom parallel to and offshore of the coastline.
Barbule. Hair that extends from a bird’s feather barb and interlocks with other barbules.
Barcoding. The identification of a species by means of DNA sequencing, often with the CO1 gene.
Barrens. A hard bottom dominated by coralline algae, with no kelps (in kelp forest regions) or corals (in coral reef regions).
Barrier island. Elongated offshore island parallel to a soft-sediment shore.
Batesian mimics. A species that is not poisonous that has evolved to resemble a poisonous model species.
Bathyal. A depth zone from 1,000 to 4,000 m.
Bathypelagic zone. The 1,000 to 4,000-m-depth zone seaward of the shelf-slope break
Benthic-pelagic coupling. The cycling of nutrients between the bottom sediments and overyling water column
Benthos. Organisms that live associated with the sea bottom. Examples include burrowing clams, sea grasses, sea urchins, acorn barnacles.
Berm. A broad area of low relief in the upper part of a beach
Between-habitat comparison. A contrast of diversity in two localities of differing habitat type (e.g., sand versus mud bottoms)
Biodiversity. See species richness
Biogenically reworked zone. The depth zone, within a sediment, that is actively burrowed by benthic organisms
Biogenic graded bedding. A regular change of sediment median grain size with depth below the sediment-water interface caused by the activities of burrowing organisms
Bilateria. A group of phyla consisting of bilaterally symmetrical organisms (including Annelida, Chordata, etc.) having a single evolutionary origin.
Bioassay. Use of a biological system; for example, some physiological parameter of an indicator species, to measure the degree of pollution.
Bioconcentration. The increase of concentration of a substance in a species, relative to its concentration in the external environment. See also Biomagnification.
Biodeposition. The deposition on the seabed of material by benthos such as suspension-feeding bivalves, in the form of feces or pseudofeces.
Biodiversity. See Species richness.
Bioerosion. Erosion caused by organisms, such as boring sponges, bivalves, and other species.
Biogenic graded bedding. A regular change of sediment median grain size with depth below the sediment–water interface caused by the activities of burrowing organisms.
Biogenically reworked zone. The depth zone, within a sediment, that is actively burrowed by benthic organisms.
Biogeography. The study of the geographic arrangements of populations and species.
Biological pump. The process by which carbon is moved to deeper waters in the ocean as sedimenting biological particles.
Biologically inspired design. The use of natural biological features and phenomena such as morphologies to design novel products for human use.
Bioluminescence. Light emission, often as flashes, by many marine organisms
Biomagnification. Increase in concentration of a substance as it moves from a species in one trophic level to a species in the next higher trophic level.
Biomass. See Standing crop
Biosphere. The entire set of living things on the earth and the environment in which they interact.
Black band disease. A disease attributed to scleractinian corals, where a black band appears, with abundant cyanobacteria.
Blastula. An early stage of embryonic development consisting of a ball of cells.
Bleaching. Referring to corals. The expulsion of zooxanthellae from corals, resulting in coral tissue losing its color and appearing to be the white color of the coral skeleton beneath the living tissue.
Blood pigment. A molecule used by an organism to transport oxygen efficiently, usually in a circulatory system (e.g., hemoglobin)
Bloom. (phytoplankton) A population burst of phytoplankton that remains within a defined part of the water column
Blowhole. A hole at the top of a cetacean’s head through which the cetacean breathes air.Blue whale unit. An equivalency between different whale species, formerly used by the International Whaling Commission in limiting the fishing take of whales.
Bohr effect. When blood pH decreases, the ability of hemoglobin to bind to oxygen decreases. An adaptation to release oxygen in the oxygen starved tissues in capillaries where respiratory carbon dioxide lowers blood pH
Boreal. Pertaining to the Northern Hemisphere, north temperate zone
Boring. Capable of penetrating a solid substratum by scraping or chemical dissolution
Bottom-up control. Refers to food webs. A control of a population that comes from change lower in a food web (e.g., control of a population of mussels by abundance of phytoplankton food).
Boundary layer. A layer of fluid near a surface, where flow is affected by viscous properties of the fluid. At the surface, fluid velocity must be zero, and the boundary layer is a thin film that depends on surface texture, fluid velocity in the “mainstream of flow,” and fluid mass properties such as salinity.
Bow wave. Water turbulence formed in the front of an object as it moves forward in the water.
Box corer. A ship-deployed benthic sampling device where a box is inserted into soft sediment and a bottom is rotated into place before the sampler is lifted toward the surface.
Brachiopods. A phylum of lophophorate invertebrates with two valves and a suspension-feeding lophophore.
Brackish sea. Semienclosed water body of large extent in which tidal stirring and seaward flow of freshwater do not exert enough of a mixing effect to prevent the body of water from having its own internal circulation pattern
Brevetoxin. Cyclic polyether neurotoxins that bind to sodium channels in nerve cells, produced by some dinoflagellate species.
Broadcast spawning. Production of planktonic gametes that can be transported by water currents.
Brooding. Maintenance of a developing juvenile within the body of the parent.
Browsers. Organisms that feed by scraping thin layers of living organisms from the surface of the substratum (eg., periwinkles feeding on rock-surface diatom films; urchins scraping a thin, filmy sponge colony from a rock)
Bryozoan. A phylum of lophophorate invertebrates, colonial, with individuals living in a flat or upright colony.
Bubble-net hunting. A hunting method, where groups of some whale species blow bubbles from the blow hole that traps prey near the surface in tight groups.
Buoyant flow. Flow of lower-salinity surface estuarine water toward the open sea.
Bycatch. The catch of a fishery that is unintended; for example, catching juvenile sturgeon when you were fishing for tuna.
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Calcareous. Made of calcium carbonate
California Current Large Marine Ecosystem. A series of coastal and offshore environments from the coast of Alaska to Central America that includes a wide series of migration routes, reproductive areas, and upwelling-feeding centers used by a number of long-distance migrating fish and marine mammals.
Cambrian explosion. A hypothetical origin and diversification of all of the Bilateria within the Cambrian geological period.
Canopy. A layer of photosynthetic organisms high off the water column, potentially shading lower layers near the seafloor.
Carbon pump. A mechanism of import of carbon dioxide to great depths by solution and storage in colder deep waters, where solubility is greater than at the surface.
Carrying capacity. The total number of individuals of a population that a given environment can sustain
Carnivore An organism that captures and consumes animals
Catadromous fish. Fish that spawns in seawater but feed and spends most of its life in estuarine or fresh water
Catch per unit effort. The fishery take divided by a series of measures such as number of vessels, hours of fishing, and number of fishers. An estimate of how much fishing is done to acquire a given catch.
Catch share. A fisheries management system in which an entire fishery is allocated to a group of fishers who had been exploiting the stock. After the allocation, a member with a share can sell this share to others.
Cementation. The deposition of mineral matter such as calcium carbonate in open spaces that results in the solifification of a habitat such as a reef.
Center-of-origin theory. Theory that high-diversity areas are centers where species originate and then spread to lower-diversity areas.
Cephalopoda. A class of Mollusca characterized by carnivory, well-developed nervous systems, complex behavior, and mobility.
Chaetognaths. See Arrowworms
Character displacement. A pattern in which two species with overlapping ecological requirements differ more when they co-occur than when they do not. The difference is usually in a morphological feature related to resource exploitation, as in the case of head size, which may be related to prey size
Chemical signaling. Communication by means of production and release of various dissolved substances.
Chemoautotrophic. An organism that depends on inorganic chemicals for its energy and principally on carbon dioxide for its carbon.
Chemolithotrophic bacteria. Bacteria that obtain energy independent of light by chemical modification of inorganic molecules.
Chemophototrophic organisms. Bacteria that obtain energy with the aid of light by chemical modification of inorganic molecules.
Chemosynthesis. Primary production of organic matter, using various substances instead of light as an energy source; confined to a few groups of microorganisms
Choanocytes. Specialized cells found in sponges.
Chondrichthyes. Fishes united by the production of a cartilaginous skeleton.
Chlorinated hydrocarbons. Compounds containing chlorine, carbon, and hydrogen, including solvents and pesticides, many of which are highly toxic.
Chlorinity. Grams of chloride ions per 1000 grams of seawater
Chloroplast. In eukaryotic organisms, the cellular organelle in which photosynthesis takes place
Chromatophore. A cell on the body surface that contains pigment. Expansion of the cell enlarges the coverage of the pigment and contraction reduces the pigment. This allows organisms such as fish, octopods, and crabs to rapidly change surface coloration and pattern.
Ciliates. Group of protistans characterized by a ciliated surface for locomotion and often a ciliated mouth.
Clade. A group of related species that arose from a single ancestor.
Climate. Weather properties that characterize a region over longer time scales such as several years to decades to centuries.
Climax community. A predictable final assemblage of species that arises as the endpoint of succession.
Cline. A regular (usually monotonic) change in gene frequency over a geographic space.
Clone. A group of individuals that have derived from a single individual by nonsexual reproduction.
Cladogram. A tree-like diagram showing evolutionary relationships. Any two branch tips sharing the same immediate node are most closely related. All taxa that can be traced directly to one node (that is they are “upstream of a node”) are said to be members of a monophyletic group.
Coastal reef. A coral reef occurring near and parallel to a coastline
Comb jellies. Members of the phylum Ctenophora, a group of gelatinous forms feeding on smaller zooplankton
Commensal. Having benefit for one member of a two-species association but neither positive nor negative effect on the other
Compensation depth. The depth of the compensation light intensity
Compensation light intensity. That light intensity at which oxygen evolved from a photosynthesizing organism equals that consumed in its respiration
Competition. An interaction between or among two or more individuals or species in which exploitation of resources by one affects any others negatively
Complex life cycle. A life cycle that consists of several distinct stages (e.g., larva and adult)
Conformer. An organism whose physiological state (e.g., body temperature) is identical to, and varies identically with, that of the external environment
Continental drift. Horizontal movement of continents located in plates moving via sea-floor spreading
Continental shelf. A broad expanse of ocean bottom sloping gently and seaward from the shoreline to the shelf-slope break at a depth of 100 to 200 m
Continental slope. See Slope
Convergence. The contact at the sea surface between two water masses converging, one plunging below the other
Copepod. Order of crustaceans found often in the plankton
Coprophagy. Feeding on fecal material
Coral reef. A wave-resistant structure resulting from cementation processes and the skeletal construction of hermatypic corals, calcareous algae, and other calcium carbonate-secreting organisms
Corer. Tubular benthic sampling device that is plunged into the bottom in order to obtain a vertically oriented cylindrical sample
Coriolis effect. The deflection of air or water bodies, relative to the solid earth beneath, as a result of the earth’s eastward rotation
Countercurrent exchange mechanism. Mechanism by which two vessels are set side by side, with fluid flowing in opposite directions, allowing efficient uptake and retention of heat, oxygen, or gas, depending upon the type of exchanger
Countershading. Condition of organisms in the water column that are dark-colored on top but light-colored on the bottom
Counter-illumination. Having bioluminescent organs that are concentrated on the ventral surface so as to increase the effect of countershading (see also countershading)
Critical depth. That depth above which total integrated photosynthetic rate equals total integrated respiration of photosynthesizers
Critical salinity. A salinity of approximately 5 to 8% that marks a minimum of species richness in an estuarine system
Ctenophora. See Comb jellies
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Daily estuary. An estuary in which tidal movements cause substantial changes in salinity at any one location on a daily basis.
Dalton. A measure of molecular mass. One dalton (Da) is equal to the mass of one hydrogen atom. Molecular mass is often measured in kDa, or thousands of daltons.
DDT. A pesticide consisting of chlorinated hydrocarbons, found to accumulate in marine species.
Dead zones. Large areas, usually at the mouths of estuaries, that have low concentrations or the absence of dissolved oxygen.
Deduction. Drawing a conclusion from the logical structure of a set of observations and thoughts.
Deep layer. The layer extending from the lowest part of the thermocline to the bottom.
Deep-scattering layer. Well-defined horizon in the ocean that reflects sonar; indicates a layer usually consisting of fishes, squid, or other larger zooplankton.
Deep-water coral mounds. Communities found in deep water dominated by scleractinian coral colonies.
Demersal. Nektonic, but associated with the seabed.
Demographic. Referring to numerical characteristics of a population (e.g., population size, age, structure).
Denitrifying bacteria. Free-living bacteria that convert nitrates to gaseous nitrogen.
Density (seawater). Grams of seawater in 1 cubic cm of fluid.
Density-dependent factors. Factors, such as resource availability, that vary with population density.
Density-mediated indirect interaction. An indirect action upon the abundance of a species in which a species not directly interacting with the first species changes in abundance. An example would be the increase in abundance of a carnivore, which results in the increase of abundance of a plant because the plant’s consumer is reduced in abundance.
Depensation. In fisheries biology, the case in which rate of population increase declines because population size is at a lower threshold. Corresponds to the Allee effect.
Deposit feeder. An organism that derives its nutrition by consuming some fraction of a soft sediment.
Detrended. A fluctuation over time in which the short-term variations are plotted but a longer-term change—for example, increasing temperature—is algebraically subtracted so that the oscillations can be visualized.
Detritus. Particulate material that enters into a marine or aquatic system. If derived from decaying organic matter, it is organic detritus.
Deuterostomes. A group of bilaterian phyla including Echinodermata and Chordata, distinguished by DNA sequence relationships and characteristics of the early embryo, such as formation of the anus at the opening of the gastrular invagination.
Diadromous. Migratory species that move between the open sea and within an estuary.
Diapause. A period of time of year when on organism transitions into a resting mode, usually with no feeding or activity, usually during an unfavorable time of year such as very low temperature.
Diatom. Dominant planktonic algal form with siliceous test, occurring as a single cell or as a chain of cells.
Diel vertical migration. Migration found in many zooplankton and fish where animals rise toward the surface at night and sink to depth during the daytime.
Diet-breadth model. A model of foraging that predicts the array of prey types included in the diet as a function of overall prey density.
Diffusion. The net movement of units of a substance from areas of higher concentration to areas of lower concentration of that substance.
Digestion efficiency. The fraction of living food that does not survive passage through a predator’s gut.
Dinoflagellate. Dominant planktonic algal form, occurring as a single cell, often biflagellate.
Direct interception. The interception of particles by suspension feeders from the water directly on threadlike structures such as cilia.
Direct release. The release of juveniles directly into the immediate environment of the parent with little dispersal.
Directional selection. Preferential change in a population, favoring the increase in frequency of one allele over another.
Dispersal. Spread of organisms, usually progeny, from one location to another.
Dissolved organic matter. Dissolved molecules derived from degradation of dead organisms or excretion of molecules synthesized by organisms.
Disturbance. A rapid change in an environment that greatly alters a previously persistent biological community.
Diurnal tide. A tidal cycle where some component (e.g., a low tide) is prominent only once a solar day.
Diversity. A parameter describing, in combination, the species richness and evenness of a collection of species. Diversity is often used as a synonym for species richness.
Diversity gradient. A regular change in species diversity correlated with a geographic space or gradient of some environmental factor.
Daily estuary. An estuary in which tidal movements cause substantial changes in salinity at any one location on a daily basis.
Dalton. A measure of molecular mass. One dalton (Da) is equal to the mass of one hydrogen atom. Molecular mass is often measured in kDa, or thousands of daltons.
DDT. A pesticide consisting of chlorinated hydrocarbons, found to accumulate in marine species.
Dead zones. Large areas, usually at the mouths of estuaries, that have low concentrations or the absence of dissolved oxygen.
Deduction. Drawing a conclusion from the logical structure of a set of observations and thoughts.
Deep layer. The layer extending from the lowest part of the thermocline to the bottom.
Deep-scattering layer. Well-defined horizon in the ocean that reflects sonar; indicates a layer usually consisting of fishes, squid, or other larger zooplankton.
Deep-water coral mounds. Communities found in deep water dominated by scleractinian coral colonies.
Demersal. Nektonic, but associated with the seabed.
Demographic. Referring to numerical characteristics of a population (e.g., population size, age, structure).
Denitrifying bacteria. Free-living bacteria that convert nitrates to gaseous nitrogen.
Density (seawater). Grams of seawater in 1 cubic cm of fluid.
Density-dependent factors. Factors, such as resource availability, that vary with population density.
Density-mediated indirect interaction. An indirect action upon the abundance of a species in which a species not directly interacting with the first species changes in abundance. An example would be the increase in abundance of a carnivore, which results in the increase of abundance of a plant because the plant’s consumer is reduced in abundance.
Depensation. In fisheries biology, the case in which rate of population increase declines because population size is at a lower threshold. Corresponds to the Allee effect.
Deposit feeder. An organism that derives its nutrition by consuming some fraction of a soft sediment.
Detrended. A fluctuation over time in which the short-term variations are plotted but a longer-term change—for example, increasing temperature—is algebraically subtracted so that the oscillations can be visualized.
Detritus. Particulate material that enters into a marine or aquatic system. If derived from decaying organic matter, it is organic detritus.
Deuterostomes. A group of bilaterian phyla including Echinodermata and Chordata, distinguished by DNA sequence relationships and characteristics of the early embryo, such as formation of the anus at the opening of the gastrular invagination.
Diadromous. Migratory species that move between the open sea and within an estuary.
Diapause. A period of time of year when on organism transitions into a resting mode, usually with no feeding or activity, usually during an unfavorable time of year such as very low temperature.
Diatom. Dominant planktonic algal form with siliceous test, occurring as a single cell or as a chain of cells.
Diel vertical migration. Migration found in many zooplankton and fish where animals rise toward the surface at night and sink to depth during the daytime.
Diet-breadth model. A model of foraging that predicts the array of prey types included in the diet as a function of overall prey density.
Diffusion. The net movement of units of a substance from areas of higher concentration to areas of lower concentration of that substance.
Digestion efficiency. The fraction of living food that does not survive passage through a predator’s gut.
Dinoflagellate. Dominant planktonic algal form, occurring as a single cell, often biflagellate.
Direct interception. The interception of particles by suspension feeders from the water directly on threadlike structures such as cilia.
Direct release. The release of juveniles directly into the immediate environment of the parent with little dispersal.
Directional selection. Preferential change in a population, favoring the increase in frequency of one allele over another.
Dispersal. Spread of organisms, usually progeny, from one location to another.
Dissolved organic matter. Dissolved molecules derived from degradation of dead organisms or excretion of molecules synthesized by organisms.
Disturbance. A rapid change in an environment that greatly alters a previously persistent biological community.
Diurnal tide. A tidal cycle where some component (e.g., a low tide) is prominent only once a solar day.
Diversity. A parameter describing, in combination, the species richness and evenness of a collection of species. Diversity is often used as a synonym for species richness.
Diversity gradient. A regular change in species diversity correlated with a geographic space or gradient of some environmental factor.
DNA. A helical, double-stranded pair of macromolecules consisting of two chains of nucleotides whose primary function is to carry of genetic information.
DNA sequence. The precise array of nucleotide bases (A, T, G, C) on a strand of DNA.
Demersal. Nektonic, but associated with the seabed.
Demographic. Referring to numerical characteristics of a population (e.g., population size, age, structure).
Denitrifying bacteria. Free-living bacteria that convert nitrates to gaseous nitrogen.
Density (seawater). Grams of seawater in 1 cubic cm of fluid.
Density-dependent factors. Factors, such as resource availability, that vary with population density.
Density-mediated indirect interaction. An indirect action upon the abundance of a species in which a species not directly interacting with the first species changes in abundance. An example would be the increase in abundance of a carnivore, which results in the increase of abundance of a plant because the plant’s consumer is reduced in abundance.
Depensation. In fisheries biology, the case in which rate of population increase declines because population size is at a lower threshold. Corresponds to the Allee effect.
Deposit feeder. An organism that derives its nutrition by consuming some fraction of a soft sediment.
Detrended. A fluctuation over time in which the short-term variations are plotted but a longer-term change—for example, increasing temperature—is algebraically subtracted so that the oscillations can be visualized.
Detritus. Particulate material that enters into a marine or aquatic system. If derived from decaying organic matter, it is organic detritus.
Deuterostomes. A group of bilaterian phyla including Echinodermata and Chordata, distinguished by DNA sequence relationships and characteristics of the early embryo, such as formation of the anus at the opening of the gastrular invagination.
Diadromous. Migratory species that move between the open sea and within an estuary.
Diapause. A period of time of year when on organism transitions into a resting mode, usually with no feeding or activity, usually during an unfavorable time of year such as very low temperature.
Diatom. Dominant planktonic algal form with siliceous test, occurring as a single cell or as a chain of cells.
Diel vertical migration. Migration found in many zooplankton and fish where animals rise toward the surface at night and sink to depth during the daytime.
Diet-breadth model. A model of foraging that predicts the array of prey types included in the diet as a function of overall prey density.
Diffusion. The net movement of units of a substance from areas of higher concentration to areas of lower concentration of that substance.
Digestion efficiency. The fraction of living food that does not survive passage through a predator’s gut.
Dinoflagellate. Dominant planktonic algal form, occurring as a single cell, often biflagellate.
Direct interception. The interception of particles by suspension feeders from the water directly on threadlike structures such as cilia.
Direct release. The release of juveniles directly into the immediate environment of the parent with little dispersal.
Directional selection. Preferential change in a population, favoring the increase in frequency of one allele over another.
Dispersal. Spread of organisms, usually progeny, from one location to another.
Dissolved organic matter. Dissolved molecules derived from degradation of dead organisms or excretion of molecules synthesized by organisms.
Disturbance. A rapid change in an environment that greatly alters a previously persistent biological community.
Diurnal tide. A tidal cycle where some component (e.g., a low tide) is prominent only once a solar day.
Diversity. A parameter describing, in combination, the species richness and evenness of a collection of species. Diversity is often used as a synonym for species richness.
Diversity gradient. A regular change in species diversity correlated with a geographic space or gradient of some environmental factor.
DNA. A helical, double-stranded pair of macromolecules consisting of two chains of nucleotides whose primary function is to carry of genetic information.
DNA sequence. The precise array of nucleotide bases (A, T, G, C) on a strand of DNA.
DOM. Dissolved organic matter.
Domain. A major evolutionary division of life.
Domoic acid. A toxic substance produced by some phytoplankton responsible for amnesic shellfish poisoning.
Down feathers. Relatively fluffy bird feathers that occupy high volume and enclose air for insulation of the body from the cold external environment.
Drag. A force created on an object because the pressure is different on either side of it.
Dredges. Samplers deployed from ships that drag the bottom and recover sediments with organisms.
Dune. A raised area of sand parallel to shore but significantly upland from the line of low tide on a beach.
Dynamic viscosity. A measure of molecular stickiness of a fluid, or a measure of resistance of a fluid to deform when a force is applied.
Dissolved organic matter.
Domain. A major evolutionary division of life.
Domoic acid. A toxic substance produced by some phytoplankton responsible for amnesic shellfish poisoning.
DOM. Dissolved organic matter.
Down feathers. Relatively fluffy bird feathers that occupy high volume and enclose air for insulation of the body from the cold external environment.
Drag. A force created on an object because the pressure is different on either side of it.
Dredges. Samplers deployed from ships that drag the bottom and recover sediments with organisms.
Dune. A raised area of sand parallel to shore but significantly upland from the line of low tide on a beach.
Dynamic viscosity. A measure of molecular stickiness of a fluid, or a measure of resistance of a fluid to deform when a force is applied.
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Ecdysozoa. A group of protostome phyla, including arthropods and nematodes, united by DNA sequence relationships and an external cuticle.
Echinodermata. Phylum characterized by a spiny skin that encloses a skeleton of interlocking calcium carbonate plates, a water vascular system, and tube feet.
Echinoidea. A class of living Echinodermata, including sea urchins, sand dollars, and heart urchins.
Ecological niche. The range of physical and biological habitats occupied by a species.
Ecology. The study of the interaction of organisms with their physical and biological environments, and how these interactions determine the distribution and abundance of the organisms.
Ecosystem. A group of interdependent biological communities and abiotic factors in a single geographic area that are strongly interactive.
Ecosystem engineer. A species whose activities strongly affect the physical structure of the environment. Often used interchangeably with foundation species.
Ecosystem services. The economic values of a variety of benefits that ecosystems perform for humans, such as the protection by coastal vegetation against storm damage.
Ecosystem-based management. An approach to conserve ecosystems that includes components of environmental protection, the social community that interacts with the ecosystem, and economic considerations.
Ectoparasite. See Parasite.
Effect size. In an experiment, the amount of change of a variable (e.g., body temperatures) between one treatment and another.
Ekman transport. Movement of surface water at an angle from the wind, as a result of the Coriolis effect.
El Niño–Southern Oscillation (ENSO). Condition in which warm surface water moves into the eastern Pacific, collapsing upwelling and increasing surface-water temperatures and precipitation along the west coasts of North and South America.
Elasticity analysis. A population analysis in which one examines the effect on population growth by a change of one parameter, such as mortality rate of a single age class.
Emigration. The departure of individuals from a given area.
Endemic. Restricted in geographic range to a particular region.
Endocrine disruptors. A series of pollutants that can disrupt endocrine or hormonal functions in marine organisms.
Endogenous rhythms. A biological rhythm that, at least for a time, is maintained without any outside environmental variation.
Endoparasite. See Parasite.
Endosymbiotic. Being symbiotic and living within the body of an individual of the associated species.
Enterococci. Bacteria of the genus Enterococcus, which can metabolize lactic acid and are ofen the cause of disease. Indicator of human fecal pollution.
Entrainment. The case when a particle is taken up with the flow of a fluid and moves with the fluid.
Environmental stress. Variously defined as (a) an environmental change to which an organism cannot acclimate and (b) an environmental change that increases the probability of death.
Enzyme polymorphisms. Genetic variation at genetic loci that code for enzymes.
Epibenthic (epifaunal or epifloral). Living on the surface of the seabed.
Epidemic spawning. Simultaneous shedding of gametes by a large number of individuals.
Epifaunal. An animal living on the surface of the seabed.
Epipelagic zone. The 0–150 m depth zone, seaward of the shelf-slope break.
Epiphyte. Microalgal organism living on a surface (e.g., on a seaweed frond).
Estuarine flow. Seaward flow of low-salinity surface water over a deeper and higher-salinity layer.
Estuarine realms. Large coastal water regions that have geographic continuity, are bounded landward by a stretch of coastline with freshwater input, and are bounded seaward by a salinity front.
Estuary. A semi-enclosed body of water that has a free connection with the open sea and within which seawater is diluted measurably with fresh water that is derived from land drainage.
EubacterIa A group of bacteria often distinguished by cell walls, presence of flagellae, and molecular sequence similarity. One of three major divisions of life.
Eukarya. One of the three major domains of life, including protists, animals, and plants.
Eukaryotes. Organisms distinguished by their cells, which have distinct nuclei and cell organelles, and in which all cells except gametes reproduce by mitosis. See also Prokaryotes.
Euphausiacea. A group of shrimplike crustacea, up to a few centimeters long; zooplankton, found usually in upwelling regions.
Euphausiid. Member of an order of holoplanktonic crustacea.
Eusocial. Social organisms where different groups of individuals in a colony serve different purposes and have morphologies determined by a combination of genotype and environment.
Eutrophic. Water bodies or habitats having high concentrations of nutrients.
Eutrophication. Addition of high nutrient concentrations to a water body.
Evaporative cooling. Cooling of an organism by evaporating water from the body surface.
Evenness. The component of diversity accounting for the degree to which all species are equal in abundance, as opposed to strong dominance by one or a few species.
Exclusive economic zone (EEZ). A coastal zone within which a nation has exclusive rights to its fisheries.
Extinction. The complete loss of all members of a taxon, such as a species.
Extremophiles. Microorganisms, often belonging to the major group Archaea, that live in extreme concentrations of metals and often very high temperatures associated with hot vents in the deep sea.
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False color. Remote sensing data often are summarized in maps, and the variation in a parameter—for example, sea-surface temperature—is represented in a color code that is not a photographic representation of the original signal but an artificial color code.
Fecal coliform bacteria. Technically, all the facultative anaerobic gram-negative, non-spore-forming, rod-shaped bacteria that ferment lactose in EC medium with gas production within 24 hours at 44.5°C. A measure of bacteria mostly originating from guts that enters waters. Believed to be correlated with disease-causing (pathogenic) bacteria.
Fecal pellets. See Pellets.
Fecundity. The number of eggs produced per female per unit time (often: per spawning season).
Fermentation. See Fermenting bacteria.
Fermenting bacteria. Bacteria that gain energy by fermentation, the anaerobic breakdown of organic material into end products such as alcohols.
Ferredoxins. Iron-sulfur proteins that mediate electron transfer, as in photophosphorylation reactions in photosynthesis.
Field experiments. Experiments that are designed to manipulate natural communities in the field.
Fish balls. A type of fish aggregation into a ball, where fish move continuously from the surface of the ball to the interior.
Fishing effort. Factors involved in bringing in landings from a fishery, including number of fishing boats, type of fishing gear, and time spent fishing.
Fitness. The rate, relative to other genotypes, at which a genotype reproduces into the next generation. Definition can also be used for alleles.
Flow cytometer. A device that uses a laser light source on particles to analyze for fluorescence and other characteristics that can distinguish the particle from other types (e.g., different types of phytoplankton cells).
Flume. A research device that uses moving water in a contained space to investigate water movement and the response of organisms to water motion.
Flushing time. The time it takes for a parcel of water to leave a confined water body such as a bay.
Foliose coral. A coral whose skeletal form approximates that of a broad, flattened plate.
Food chain. An abstraction describing the network of feeding relationships in a community as a series of links of trophic levels, such as primary producers, herbivores, and primary carnivores; a linear connection of organisms to show the feeding linkages of predators and prey.
Food chain efficiency. Amount of energy or some other quantity extracted from a trophic level, divided by the amount of energy produced by the next-lower trophic level.
Food web. A network describing the feeding interactions of the species in a defined region.
Foraminifera. Protozoan group, individuals of which usually secrete a calcareous test; both planktonic and benthic representatives.
Foraminiferan ooze. A deep-sea sediment composed primarily of skeletons of Foraminifera.
Foundation species. Species that are structurally important for the organization of a community. Includes abundant species like reef-forming corals and sea grasses.
Founder principle. A small colonizing population is genetically unrepresentative of the source of population.
Framework builders. In coral reefs: dominant coral species that comprise most of the calcium carbonate production of the reef.
Free amino acids. Amino acids that are synthesized and kept in free concentration in cells for the purpose of osmoregulation.
Free spawning. Gametes are released directly into the water column.
Free-water techniques. Methods of measuring primary productivity by directly measuring oxygen changes in natural waters, taking into account daily changes in photosynthesis and losses and gains of oxygen between the water column and the atmosphere.
Frequency-dependent selection. Natural selection depends on the frequency of alleles in the population. For example, an allele might be favored more when it is rare than when it is common.
Freshet. An increase of water flow into an estuary during the late winter or spring, owing to increased precipitation and snow melt in the watershed.
Frond. In seaweeds: typically, a flattened structure attached to the stipe, where much of the photosynthesis occurs.
Front. A major discontinuity separating ocean currents and water masses in any combination.
Fugitive species. A species adapted to colonize newly disturbed habitats.
Functional biology. The study of how an organism carries out the basic functions such as reproduction, locomotion, feeding, and the cellular and biochemical processes relating to digestion, respiration, and other aspects of metabolism.
Functional group. A groups of species with similar ecological function (e.g., herbivore species).
Functional redundancy. The case in which the ecological function (e.g., nitrogen fixation) of one species in a community can be replaced by the presence of another ecologically similar species.
Fyke net. Net usually staked to the bottom, sometimes with leading wings that guide fishes moving with the current into the main net bag.
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Gametophyte. Haploid stage in the life cycle of a plant.
Gastropoda. A class of mollusks characterized usually by a spiral shell, a muscular foot, and twisting of the embryo during development.
Gelatinous zooplankton. Zooplankton that have a gelatinous support skeleton, including many distantly related phyla such as Cnidaria, Ctenophora, and members of the Chordata.
Gene duplication. A process whereby a gene is duplicated owing to an error in DNA duplication in meiosis or even a duplication of a whole chromosome. Genes may be duplicated by a number of other processes related to DNA replication and repair.
Gene expression. The degree to which a given gene is stimulated to produce a gene product such as a protein.
Gene family. A group of genes that are similar in sequence and usually function and all derive from the same ancestral gene, usually by means of gene duplication and natural selection.
Generation time. The time period from birth to average age of reproduction.
Genetic code. The arrangement of nucleotides to form a code specifying different amino acids.
Genetic drift. Changes in allele frequencies that can be ascribed to random effects.
Genetic locus. A location on a chromosome (possibly of a diploid organism with variants that segregate according to the rules of Mendelian heredity).
Genetic polymorphism. Presence of several genetically controlled variants in a population.
Genome. The total functioning DNA of an organism.
Genotype. The genetic makeup of an organism; with respect to a given genetic locus, the alleles it carries.
Genotype-by-environment interaction. The same genotype may have a different phenotype when raised in different environments.
Genus. (plural: genera) The level of the taxonomic hierarchy above the species but below the family level.
Geostrophic flow. Movement of water in the oceans as a combined response to the Coriolis effect and gravitational forces created by an uneven sea surface.
Geotactic. Moving in response to the earth’s gravitational field.
Gill arch. A part of a fish skeleton that supports the gills.
Gill net. Fish net with a mesh size designed to trap by the gills a restricted size class of fish.
Gill rakers. Projections along the fish gill arch.
Gliders. Autonomous underwater vehicles that can use simple balancing devices and vanes to move the vehicle through the water column.
GIS: Geographic Information System. A system that allows automatic location of information suitable for mapping. Usually involves a software system that takes geographic position data and other data (e.g., type of bottom sediment) in order to create a map. Data on processes (e.g., current speed) can be incorporated to make a geographic model of flow.
Global conveyor belt system. A movement of water currents that couples surface water motion with deep thermohaline water motion.
Global positioning system (GPS). An electronic device that uses positioning signals from satellites in order to locate precisely latitude and longitude. Now used nearly exclusively for locating ship sampling stations at sea, but also useful for locations near and on shore.
Global warming. Predicted increase in the earth’s oceanic and atmospheric temperature, owing to additions of carbon dioxide to the atmosphere, often as a result of human activities.
Glycoprotein. A protein having a carbohydrate component.
Gonochoristic. Having separate sexes.
Grab. Benthic sampling device with two or more curved metal plates designed to converge when the sampler hits bottom, grabbing a specified volume of bottom sediment.
Gravity corers. A coring device that drops into the sediment with the aid of a weight, simply by force of gravity.
Grazer. A predator that consumes organisms far smaller than itself (e.g., copepods graze on diatoms).
Greenhouse effect. Carbon dioxide traps solar-derived heat in the atmosphere near the earth.
Greenhouse gases. Gases such as carbon dioxide that enable the greenhouse effect.
Gregarious settling. Settlement of larvae that have been attracted to members of their own species.
Gross primary productivity. The total primary production, not counting the loss in respiration.
Growth efficiency. The efficiency that ingested food is converted into somatic growth.
Guild. A group of species, possibly unrelated taxonomically, that exploit overlapping or similar resources.
Guyot. A submarine oceanic seamount and inactive volcanic mass whose summit is below the sea surface, usually with a flattened top.
Gyre. Major cyclonic surface current systems in the oceans.
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Habitat fragmentation. A previously continuous habitat is broken up into fragments, perhaps by human disturbance and development.
Hadal. The depth zone corresponding to oceanic trenches.
Halocline. Depth zone within which salinity changes maximally.
Harmful algal bloom. A bloom of (usually) planktonic microalgae belonging to a strain of a species that has a toxin harmful to marine organisms or humans consuming marine organisms.
Heat of vaporization (water). The amount of heat required to convert a unit mass of water at its boiling point into vapor without an increase in temperature.
Heat-shock proteins. Proteins that are produced under heat stress and reduce the unfolding of functioning enzymes.
Herbivore. An organism that consumes plants. More generally, an organism that consumes photosynthetic organisms.
Heritable character. A morphological character whose given state can be explained partially in terms of the genotype of the individual.
Hermaphrodite. An individual capable of producing both eggs and sperm during its lifetime.
Hermatypic. Reef-building.
Heterocysts. Enlarged cells in cyanobacteria, where nitrogen fixation occurs.
Heterotrophic algae. Algae that take up organic molecules as a primary source of nutrition.
Heterozygote. With respect to a given genetic locus, a diploid individual carrying two different alleles.
Highly stratified estuary. An estuary having a distinct surface layer of fresh or very-low-salinity water, capping a deeper layer of higher-salinity, more oceanic water.
High-nitrogen–low-productivity (HNLP) sites. Areas of the surface ocean that have relatively high concentrations of nitrogen but nevertheless have low primary productivity, probably because of iron limitation.
Hirudinea. The leeches, a class of annelids having a fixed number of segments, lacking parapodia or chaetae, and typically parasitic.
HNLP. See High-nitrogen–low-productivity (HNLP) sites.
Holdfast. In seaweeds: a structure that attaches the seaweed to the substratum.
Holobiont. A host organism (animal or plant) and all of its symbiotic microbial organisms.
Holoplankton. Organisms spending all their life in the water column and not on or in the seabed.
Holothuroidea. A class of Echinodermata, the sea cucumbers, characterized by a worm shape, a crown of tentacles with tube feet, and either a deposit- or suspension-feeding ecology.
Homeotherm. An organism that regulates its body temperature despite changes in the external environmental temperature.
Homologous. Having the same evolutionary origin.
Homozygote. With respect to a given genetic locus, a diploid individual carrying two identical alleles.
Hot vents. Openings in oceanic ridge rocks of volcanic origin with hot water emanating with concentrated metals and sulfide.
Hydrogen bonds. A chemical bond with a hydrogen atom between two negatively charged atoms (e.g., oxygen).
Hydrostatic skeleton. A flexible skeleton supported by fluid pressure, usually with a body wall that can be adjusted by opposing muscle sets, working against the fluid fill.
Hydrothermal vents. Sites in the deep-ocean floor where hot, sulfur-rich water is released from geothermally heated rock.
Hyperosmotic. Having a higher salt content, or higher content of materials that affect osmosis (e.g., osmolytes), within cells than exists in the surrounding external water environment.
Hypoosmotic. Having a lower salt content, or lower content of materials that affect osmosis, within cells than in the surrounding external water environment.
Hypothesis. A refutable statement about one or a series of phenomena.
Hypoxia. The presence of low concentrations of oxygen in the water that is stressful to marine organisms.
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Ice algae. A wide variety of microalgae and macroalgae that live in association with ice floes in polar oceans.
Immunofluorescence. A method of identifying cells by means of using antibodies that are coupled to fluorescent dyes.
Impingement. When a screen in a power plant captures fish or other marine organisms as water is sucked into an intake channel.
Implanted tags. Devices of varying design that are implanted in marine organisms for identification.
Indirect effect. An ecological effect of one species on another that is mediated through changes in abundance of a third species that interacts with the first species.
Individual transferrable quota (ITQ) system. An arrangement in which a fishing entity can transfer its proportional right to a fishery to another fishing entity.
Inducible defense. A defense against predation that grows or develops after an individual is exposed to a predator.
Induction. Reaching a conclusion from an accumulation of facts.
Inertial forces. Forces where an object tends to keep moving after ceasing to apply a force to that object.
Infaunal. Living within a soft sediment and being large enough to displace sedimentary grains.
Inorganic carbon. Carbon in molecules not manufactured by organisms (e.g., as CO2).
Interference competition. Interspecific competition where individuals of one species directly interfere and prevent individuals of a competing species from access to a limiting resource.
Intermediate predation-disturbance effect. Predation maximizes the number of coexisting and competing species at some intermediate level of predation or disturbance.
International Whaling Commission. An international treaty-based organization that sets policy for whaling practices and quotas, with the objective of conservation and recovery of whale stocks.
Intersexual selection. Selection for traits of one sex that are involved in interactions with the other sex, such as selection for production of bright color in males that attracts mating females.
Interspecific competition. Condition in which one species’ exploitation of a limiting resource negatively affects another species.
Interstitial. Living in the pore spaces among sedimentary grains in a soft sediment.
Intertidal zone. The zone between the highest and lowest extent of the tide.
Intrasexual selection. Selection among members of the same sex, for example, selection among body size that gives increases access to mating with females.
Invasive species. A species that successfully disperses to a new region and then increases greatly in abundance and area in the new region.
Isopycnal. A line connecting waters of equal density.
Isotonic. Having the same overall concentration of dissolved substances as a given reference solution.
Iteroparity. The condition where an individual reproduces more than once.
IUCN. International Union for Conservation of Nature.
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Kelp. A group of brown seaweeds belonging to the group Laminariales, characterized by rapid growth and occurrence as foundation species of subtidal kelp forests.
Kelp forests. Shallow subtidal communities in relatively cold water, dominated by kelps.
Keystone species. A predator at the top of a food web, or discrete subweb, capable of consuming organisms of more than one trophic level beneath it. Often more broadly defined as any species that has broad impacts on a community.
Kinematic viscosity. The dynamic viscosity divided by water density.
Krill. See Euphausiacea.
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Laminar flow. The movement of a fluid where movement of the entire fluid is regular and with parallel streamlines.
Laminariales. The group of seaweeds commonly called kelps.
Landings. The catch of a given fishery.
Langmuir circulation. Under steady winds, circulation at the surface is driven into the forms of vertically rotating cells that leave linear traces at the surface, where the cells cause alternating rows of convergence and divergence of water and entrained materials.
Larva. A discrete stage in many species, beginning with zygote formation and ending with metamorphosis.
Larvacea. A group of planktonic tunicates that secrete a gelatinous “house,” used to strain unsuitable particles (large particles are rejected). An inner filter apparatus of the house, the so-called food trap or particle-collecting apparatus, is used to retain food particles.
Lateral-line system. In fish: a series of sense organs arranged in a line along the side; used in mechanoreception.
Latitude diversity gradient. The general case where diversity increases from high to low latitude.
LC50. The concentration of a toxic substance that produces 50 percent mortality in an experimental population after a specified time.
LD50. The value of a given experimental variable required to cause 50 percent mortality.
Leaching. The loss of soluble material from decaying organisms.
Lecithotrophic larva. A planktonic-dispersing larva that lives off yolk supplied via the egg.
Leeward side. The side of an island opposite from the one facing a persistent wind.
Leslie matrix. A matrix of probabilities of reproduction and mortality of difference age classes in a population.
Lichen. A composite symbiosis of filaments of fungi and either algae or cyanobacteria.
Life table. A table summarizing statistics of a population, such as survival and reproduction, all broken down according to age classes.
Light-harvesting complex. The range of photosynthetic pigments that capture light energy and transfer energy for photosynthesis.
Limiting nutrients. Those nutrients that regulate the growth of photosynthetic organisms.
Living shore. A shoreline whose structure is determined by the dominating presence of one or a group of living species. Examples: salt marsh, mangrove, oyster bed.
Locus. See Genetic locus.
Logistic population growth. Population growth that is modulated by the population size relative to carrying capacity. Population growth declines as population approaches carrying capacity, and is negative when population size is greater than carrying capacity.
Longlines. Lines with hooks at regular intervals used to catch fish.
Longshore current. A current moving parallel to a shoreline.
Lophophorates. A group of phyla, including Brachiopoda, Bryozoa, and Phoronida, united by the presence of a lophophore, which is a horseshoe- or spiral-shaped feeding structure.
Lophophore. A horseshoe- or spiral-shaped feeding structure with tentacles belonging to lophophorate phyla.
Lophotrochozoa. A group of bilaterian phyla within the Protostomia that are evolutionarily related.
Luciferase. A group of oxidative enzymes that catalyze the transformation of luciferin into a light-emitting substance.
Luciferin. A light-emitting compound used by many species in bioluminescence.
Lysis. The breaking open of a cell by destruction of cell membranes resulting from the invasion and reproduction of population of viruses.
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Macroalgae. Algae large enough to be detected with the naked eye. Often used as a synonym of seaweeds.
Macrobenthos (macrofauna or macroflora). Benthic organisms (animals or plants) whose shortest dimension is greater than or equal to 0.5 mm.
Macrofauna. Animals whose shortest dimension is greater than or equal to 0.5 mm.
Macrophyte. An individual alga large enough to be seen easily with the unaided eye.
Macroplankton. Planktonic organisms that are 200–2,000 µm in size.
Madreporite. A sievelike plate on the aboral surface of echinoderms that connects the external environment with the internal water vascular system.
Mainstream current. The flow in a part of the fluid (e.g., in a tidal creek) that is well above the bottom or well away from a surface and essentially not under the influence of the boundary layer. See also Boundary layer.
Maintenance metabolism. The energy required to maintain an organism at rest.
Male dimorphism. The case where males occur in at least two distinct forms.
Mangel. See Mangrove forest.
Mangrove forest. A shoreline ecosystem dominated by mangrove trees, with associated mudflats.
Mantle. A rock layer of the earth beneath the crust.
Marginal seas. Seas located usually in coastal areas where local conditions and past history create distinct local conditions.
Mariculture. The rearing of organisms in confined areas for food or food products.
Marine protected area (MPA). A conservation geographic unit designed to protect crucial communities and to provide reproductive reserves for fisheries that hopefully will disperse over wider areas.
Marine snow. Fragile organic aggregates, resulting from the collision of dissolved organic molecules or from the degradation of gelatinous substances such as larvacean houses. Usually enriched with microorganisms.
Marine trophic index. A measure of the dominant trophic level in a given fishery area.
Mate selection. See Intersexual selection.
Maximum sustainable yield (MSY). In fisheries biology, the maximum sustainable catch obtainable per unit time under the appropriate fishing rate.
Mechanical displacement. Burrowing where the animal uses a structure to dig out sediment to form a burrow.
Median grain size. If a sediment sample is divided into a series of size classes by sieves, the median grain size is the size where cumulative addition of sediment of size classes crosses the 50 percent threshold of the total sample.
Megaplankton. Planktonic organisms that are greater than or equal to 2,000 µm in size.
Meiobenthos (meiofauna or meioflora). Benthic organisms (animals or plants) whose shortest dimension is less than 0.5 mm but greater than or equal to 0.1 mm.
Meiofauna. Animals whose shortest dimension is less than 0.5 mm but greater than or equal to 0.1 mm.
Membrane order. The degree of packing of the structural phospholipids in a cell membrane.
Meroplankton. Organisms that spend part of their time in the plankton but also spend time in the benthos (e.g., planktonic larvae of benthic invertebrates).
Merostomata. The class of arthropods including horseshoe crabs.
Mesopelagic. The 200–1,000 m depth zone, seaward of the shelf-slope break.
Messenger RNA (mRNA). RNA molecule that is the template for the amino acid sequence of a protein.
Metabolic rate. The overall rate of biochemical reactions in an organism. Often estimated by rate of oxygen consumption in aerobes.
Metal-rich granules. Small solid deposits of metal compounds found widely in marine species environmentally exposed to metals.
Metamorphosis. Major developmental change as the larva develops into an immature adult.
Metapopulation. A group of interconnected subpopulations, usually of subequal size. The features of individuals now found in one subpopulation might have been determined by conditions affecting them when they were located in another subpopulation.
Metazoa. Equivalent to all of the animals.
Methanogenic bacteria. Anaerobic bacteria that use carbon dioxide as a source of carbon and produce methane as a by-product.
Methylmercury. Organic form of mercury and the form of mercury that is most easily bioaccumulated.
Microarray. An array of sequences, usually attached to a plastic chip, used to test for binding of similar sequences extracted from a species. Used to estimate the degree of gene expression or the presence of given DNA sequences in a given individual.
Microbenthos (microfauna or microflora). Benthic organisms (animals or plants) whose shortest dimension is less than 0.1 mm.
Microbial loop. A part of a marine food web where bacteria is consumed by protistans, which are eventually consumed by larger consumers in the food web.
Microbial stripping hypothesis. When a deposit feeder feeds on sediment, it digests the microbial organisms on particulate organic matter with great efficiency but digests the particulate organic matter itself with very low efficiency.
Microfauna. Animals whose shortest dimension is less than 0.1 mm.
Microsatellites. DNA sequences used as genetic markers. Usually consist of highly repetitive sequences that are quite variable and therefore useful in marking individual populations of a species.
Migration. A directed movement of an organism between specific areas.
Mixed tides. Tides where the vertical extent of the tide is very uneven, usually with two very different alternating low tides.
Mixing depth. The water depth to which wind energy evenly mixes the water column.
Mixoplankton. Planktonic organisms that can be classified at several trophic levels. For example, some ciliates can be photosynthetic but also can ingest other plankton and are heterotrophic or may retain ingested chloroplasts.
Moderately stratified estuary. An estuary in which seaward flow of surface low-salinity water and moderate vertical mixing result in a modest vertical salinity gradient.
Modular. Referring to organisms that consist of repeated connected units that are genetically identical and of similar ecological function (e.g., a coral colony).
Module. A unit in a modular organism.
Molecular clock. The dating of a biological event (e.g., origin of an evolutionary group) by using the rate at which DNA sequences change over time.
Mollusks. A phylum of protostome mollusks characterized usually by a mantle, calcium carbonate shell(s), and unsegmented body; including snails, bivalves, and squids.
Momentum boundary layer. A layer of water near a surface where physical transport of fluid is affected by the presence of the surface.
Monoclonal antibodies. Antibodies produced by a single immune cell or daughters of that identical cell.
Monophyletic. Refers to a group of species that all have a single common ancestral species.
Monoplacophora. Cap-shaped mollusks, which may include ancestral forms similar to the Mollusca.
Mucous-bag suspension feeder. Suspension feeder employing a sheet or bag of mucus to trap particles nonselectively.
Müllerian mimicry. Mimicry where two species resemble each other and both are toxic.
Multibeam sonar. A sonar signal in a fan shape that can map the spatial arrangement of depth on the sea floor and even detect properties of the seabed.
Mustelidae. A family of mammals including minks and otters.
Mutualism. An interaction between two species in which both derive some benefit.
Mycelium. A tangled mass of hairlike threads of ascomycetes.
Mycorrhizae. Fungi involved in a symbiosis with roots of plants and aiding in plant nutrient uptake.
Mysticeti. Group of Cetacea that use baleen for feeding.
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Nanoplankton. Planktonic organisms that are 2–20 µm in size.
NAO. See North Atlantic Oscillation.
Natural philosophy. A general approach to studying environmental science and biology that was popular in the nineteenth century, when there were few specialists but scientists who studied diverse subjects.
Natural selection. The differential contribution of genes to the next generation because of fitness differences.
Neap tides Tides occurring when the vertical range is minimal.
Negative correlation. An inverse relationship between the values of one parameter and the values of another.
Nekton. Organisms with swimming abilities that permit them to move actively through the water column and to move against currents.
Nematoblast. Cells found in Cnidaria, which contain hooks, stingers, or mucus to entrap prey.
Nematocysts. The stinging, hooking, or mucus-producing elements that emerge from nematoblasts.
Nematoda. Free-living and parasitic worms with a cuticle and longitudinal muscles.
Nemertea. Elongate free-living worms, with complete gut; carnivorous, using barbed proboscis to kill prey.
Neritic. Seawater environments landward of the shelf-slope break.
Net primary productivity. Total primary production, minus the amount consumed in respiration.
Neurotoxic shellfish poisoning. Uptake by shellfish of bevetoxin, which is found in dinoflagellate species such as Gymnodinium breve. Brevetoxin causes respiratory problems for humans.
Neuston. Planktonic organisms associated with the air–water interface.
Neutral theory of community ecology. Random interactions, combined with occasional extinctions and speciation events, result in indefinite coexistence of many species.
New production. Primary production in a body of water that can be explained by import of usually inorganic nutrients from outside the system, as in upwelling.
Niche. A general term referring to the range of environmental space occupied by a species.
Niche overlap. An overlap in resource requirements by two species.
Niche structure. Any predictable partitioning by coexisting species of a habitat into subhabitats.
Nitrification. A process caused by nitrifying bacteria, where ammonium is oxidized to nitrite or nitrate.
Nitrogen fixation. The conversion of gaseous nitrogen to nitrate or ammonium by specialized bacteria.
Nonconsumptive effect. A response within a food web when one predatory species changes its behavior (perhaps reducing its activity in response to its own predator) and as a consequence reduces its impact on a prey species.
Noncumulative toxic substances. Substances that do not increase in concentration in the body over time.
Nonpoint source. Pollution source that comes to the watershed from many points along a water body, as opposed to from a single source, such as an industrial pipe.
Nonrenewable resource. A resource that, when consumed, is no longer available over the lifetime of the organism.
North Atlantic Oscillation (NAO). A cycle of changing difference in air pressure between a low atmospheric pressure over Iceland at about 64° N latitude and a higher atmospheric pressure over the Azores, at approximately 38° N latitude.
North Pacific Transition Zone. A belt across the Pacific centered at about 35–40° N latitude where frontal transitions often result in high primary productivity.
No-slip condition. The condition where water has zero velocity when in contact with a surface.
No-take area. Geographic area where by law no one is allowed to fish or collect biological specimens. Rules could apply to one or all species.
No-take sanctuary. A marine preserve with a rule that prevents taking of a given species or group of species.
Nucleotides. A building block of a DNA or RNA strand.
Nuisance bloom. A rapid increase of one or only a few species of phytoplankton, resulting in cell densities high enough to cause discoloration of the surface water, possible increase of toxins, and degradation of water quality aspects such as dissolved oxygen.
Null hypothesis. A hypothesis that states an experimental treatment will result in no change, relative to a control or relative to a starting measurement before the experimental treatment is applied.
Nutrient cycling. The pattern of transfer of nutrients between the components of a food web.
Nutrients. Those constituents required by organisms for maintenance and growth (we use this term in this book in application to plants).
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Ocean acidification. The decline of pH in the ocean, owing to additions of carbon dioxide in the atmosphere and subsequent dissolution in seawater.
Ocean observatories. Remote sensing systems, on the seafloor or in mid waters, used to collect data and transmit them to land-based laboratories.
Oceanic. Associated with seawater environments seaward of the shelf-slope break.
Oceanic boundary currents. A distinct ocean current that runs parallel to and offshore of the coast usually on the western sides of oceans (e.g., the Gulf Stream).
Oceanic crust. A layer of earth’s crust that underlies the ocean basins. Overlies the earth’s mantle.
Oceanic ridge. A sinuous volcanic ridge rising from the deep-sea floor.
Odontoceti. A group of Cetacea characterized by reduced appendages, flukes, and teeth used in carnivory.
Oligochaeta. A class of Annelida that are wormlike, usually free living, and have chaetae but lack parapodia; includes earthworms.
Oligotrophic. Refers to water bodies or habitats with low concentrations of nutrients.
Omnivory. Being able to feed in more than one distinct way (e.g., an organism capable of carnivory and herbivory).
Operculum. Hard organic covering of the foot of gastropods, used to protect against predation or desiccation.
Ophiuroidea. Class of Echinodermata that look like sea stars but have very flexible arms.
Opportunists. Species with life-history traits that allow colonization of numerous habitat types and rapid subsequent population growth.
Optimal foraging theory. A theory designed to predict the foraging behavior that maximizes food intake per unit time.
Organic. Deriving from living organisms.
Organic carbon. Carbon derived from organic molecules such as amino acids.
Organic nutrients. Nutrients in the form of molecules synthesized by or originating from other organisms.
Organic osmolytes. Compounds including amino acids and urea that are used in osmoregulation.
Oscillation, climate. A fluctuation in air pressure characteristics, wind systems, sea-surface temperature (SST), or other weather features that occur on the geographic scale of an ocean, such as throughout the North Atlantic Ocean or perhaps even the world ocean. Example: El Nino Southern Oscillation, North Atlantic Oscillation
Osculum. An opening that is used for the exit of wastewater in a living sponge.
Osmoconformer. An organism whose body fluids change directly with a change in the concentrations of dissolved ions in the external medium.
Osmoregulator. An organism that regulates the concentration of dissolved ions in its body fluids irrespective of changes in the external medium.
Osmosis. The movement of pure water across a membrane from a compartment with relatively low dissolved ions to a compartment with higher concentrations of dissolved ions.
Osmotic pressure. A pressure that corresponds to the different osmotic conditions on either side of a biological surface, such as a membrane.
Osteichthyes. The bony fishes.
Otolith. A small mass of calcium carbonate, used in the inner ear of a fish for perception of balance. The mass often grows in increments that can allow us to determine the age of the fish.
Outwelling. The outflow of nutrients from an estuary or salt marsh system to shelf waters.
Overfishing. Case in which high degree of fishing results in decline of a fish population to unsustainable levels.
Oviparous. Reproduction in which eggs are laid and hatch outside the mother’s body, with little or no development within the mother. An example would be an unfertilized egg shed into the water that is fertilized by planktonic sperm.
Ovoviparous. Fertilization is internal, but eggs develop within the mother’s body with no nutrients supplied. Eggs are eventually released into the environment and hatch.
Oxygen dissociation curve. A curve showing the percent saturation of a blood pigment, such as hemoglobin, as a function of oxygen concentration of the fluid.
Oxygen electrode. An electrode used to measure oxygen concentration in the water.
Oxygen minimum layer. A depth zone, usually below the thermocline, in which dissolved oxygen is minimal.
Oxygen technique (primary productivity). The estimation of primary productivity by the measurement of the rate of oxygen increase.
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Pacific Decadal Oscillation. A climatic oscillation in the Pacific of a period of 20–30 years, in which cool and warm waters exchange locations in the eastern and western Pacific north of 20° N latitude.
PAHs. See Polycyclic aromatic hydrocarbons.
PAR. See Photosynthetically active radiation.
Paradox of the plankton. The coexistence of many species of phytoplankton, despite evidence of resource limitation.
Paralytic shellfish poisoning (PSP). The ingestion of dinoflagellates containing saxitoxin by bivalves, which in turn may be eaten by humans, who are poisoned.
Parapatric speciation. The differentiation into distinct species of populations experiencing some gene flow.
Parapodia. Paired structures on polychaetes, used for locomotion.
Parasite. An organism living on (ectoparasites) or in (endoparasite), and negatively affecting, another organism.
Partially mixed estuary. An estuary or area of an estuary with a gradient of lower-salinity to higher-salinity water as one moves from the surface to the bottom; mixed vertically by wind and tidal motion.
Particulate organic matter (POM). Particulate material in the sea derived from the decomposition of the nonmineral constituents of living organisms.
Patchiness. A condition in which organisms occur in aggregations.
PCR. See Polymerase chain reaction.
Peat. A sediment that is rich in organic matter.
Pelagic. Living in the water column seaward of the shelf-slope break.
Pelagic trawls. Fishing by means of a net, which is towed in the water column and kept open by boards at the net opening.
Pellets. Compacted aggregations of particles resulting either from egestion (fecal pellets) or from burrow-constructing activities of marine organisms.
Penetration anchor. In hydraulically burrowing organisms, any device used to penetrate and gain an initial purchase on the sediment so that the body can be thrust in farther.
Pennate diatoms. Diatoms that are bilaterally symmetrical and usually elongate. They tend to occur on the sea bed rather than in the water column.
Peptides. Chains of amino acids; often portions of a protein molecule, or functional molecules in their own right.
Petersen grab. A bottom grab that enters the seabed by gravity and then closes as a chain pulls the sampler upward toward the ship.
pH. Measure of the acidity or basicity of water; pH = –log10 of the activity of hydrogen ions in water.
Phase shift. A predictable response in the form of a change of community composition to a new state in response to an environmental change.
Phenotype. The form of an organism or a trait (as opposed to its genotype).
Phenotypic plasticity. The capacity of an individual of the same genotype to produce different phenotypes under different environmental conditions. Nongenetic potential variability within the range of a single individual.
Phi scale. Scale used for measuring the grain size of sediments; phi = –log2 (grain diameter).
Phleger corer. A small, gravity-driven bottom corer.
Phoronida. A phylum of wormlike animals, having a lophophore and living infaunally.
Photic zone. The depth zone in the ocean extending from the surface to that depth permitting photosynthesis.
Photoinhibition. Reduction or suppression of photosynthesis due to high light intensity.
Photorespiration. Enhanced respiration of plants in the light relative to dark respiration.
Photosynthate. A substance synthesized in the process of photosynthesis.
Photosynthetic quotient. In photosynthesis, the moles of oxygen produced, divided by the moles of carbon dioxide assimilated.
Photosynthetic rate. The rate of conversion of dissolved carbon dioxide and bicarbonate ion to photosynthetic product.
Photosynthetically active radiation (PAR). That part of the light spectrum that can be used in photosynthesis.
Phototactic. Moving in response to light.
Phylogeography. The study that combines geographic and evolutionary aspects of the distribution of species.
Physiological integration. A general term signifying the degree of coordination of different physiological and biochemical processes within a cell or within an organism.
Physiological race. A geographically defined population of a species that is physiologically distinct from other populations.
Physiological tolerance. The degree to which an organism can survive an extreme environment, by virtue of its physiological traits.
Phytodetritus. Particulate organic matter settling through the water column that derives from dead phytoplankton.
Phytoplankton. The photosynthesizing organisms residing in the plankton.
Pinnipedia. A diverse group of semi-aquatic marine mammals with fin-shaped feet, including seals, sea lions, and walruses.
Planktivorous. Feeding on planktonic organisms.
Plankton. Organisms living suspended in the water column and incapable of moving against water currents.
Planktotrophic larva. Planktonic-dispersing larva that derives its nourishment by feeding in the plankton.
Plant nutrients. Substances required by plants for growth.
Planula. The planktonic larval form produced by scleractinian corals and coelenterates.
Plasticity. See Phenotypic plasticity.
Plate. Major section of the earth’s crust, bounded by such features as midocean ridges.
Platyhelminthes. A phylum of invertebrates, commonly known as flatworms, with free-living and parasitic representatives.
Pleistocene. Period of time, going back to approximately 2 million years before the present, in which alternating periods of glaciation and deglaciation dominated the earth’s climate.
Pleuston. Refers to plankton that have a float protruding above the sea surface, such as the Portuguese man-of-war.
Pneumatocysts. Gas-containing floats found in some brown seaweeds, such as kelps.
Poecilogonic. Species with more than one larval developmental mode.
Pogonophora. A phylum of wormlike animals that are gutless, have a symbiosis with bacteria, and are usually found in deep-sea environments.
Poikilotherm. An organism whose body temperature is identical to that of the external environment.
Point source. A pollution source from a confined spot, such as an industrial pipe.
Polychaeta. A class of annelids characterized by paired parapodia, which are used for locomotion.
Polychlorinated biphenyls (PCBs). Usually very toxic compounds manufactured for insulation, but released into the marine and estuarine environments.
Polycyclic aromatic hydrocarbons (PAHs). Derivatives from fossil fuels that are very toxic and known to be carcinogenic.
Polymerase chain reaction (PCR). A reaction based on fluctuating thermal conditions used to amplify DNA by means of annealing specific strands with nucleotides that bind and amplify the original DNA strand to great abundance.
Polymorphism. The presence of coexisting and distinctly different forms of a species; may be caused by genetic differences or phenotypic plasticity.
Polyp. An individual of a solitary coelenterate or one member of a coelenterate colony.
Polyphyletic. Refers to a group of species that do not have one common ancestor species.
Polyplacophora. A class of Mollusca, comprising the chitons.
Poorly sorted sediments. Sediment consisting of a wide range of mixed groups of differently sized particles.
Population density. Number of individuals per unit area or volume.
Pop-up satellite archival tags. Fish tags that are designed to become detached from fish after a time, so that they can rise to the surface and be detected by a global positioning system.
Porifera. The phylum comprising the sponges.
Positive correlation. An increase in one variable occurs with an increase in another variable, or a decrease in one variable occurs with a corresponding decrease in another variable.
Postmating isolation. Reproductive isolation between species due to mechanisms such as genetic compatibility, despite the fact that mating occurs.
Post-translational modification. Chemical change (e.g., attachment of oligosaccharides) in a protein after it is translated, or after its amino acid sequence is specified.
Pound net. A blind-ended net that captures fish at the blind end.
ppt. A measure of the salt content of seawater in terms of kilograms of salt per kilogram of water, reckoned in parts per thousand. A conductivity version of this measure is the psu, which differs from ppt by very little, on the order of 0.02 psu or less.
Practical salinity unit. See psu.
Precision. The repeatability of a measurement. A measurement can be precise, but not accurate. See also Accuracy and Resolution.
Predation. The consumption of one organism by another.
Predator. An organism that consumes another living organism (carnivores and herbivores are both predators by this definition).
Premating isolation. Reproductive isolation between species that involves mechanisms such as time of reproduction and mate-recognition signals.
Pressure drag. A difference in pressure upstream and downstream of an object in a flow.
Primary producer. An organism capable of using the energy derived from light or a chemical substance in order to manufacture energy-rich organic compounds.
Primary production. The production of living matter by photosynthesizing organisms or by chemosynthesizing organisms. Usually expressed as grams of carbon per square meter per year.
Primary treatment. Simple screening of organic particulates before sewage is released into the water.
Priority effect. Colonization of an unoccupied site by a species, followed by continued occupation of that site by this species, preventing all other species from invading.
Productivity. The amount of biological material (usually expressed as carbon) produced per unit time (usually expressed per unit of area in the ocean).
Prokaryotes. Organisms distinguished by cells that lack true nuclei or organelles and do not reproduce by means of mitosis.
Protandrous.An animal that, when sexually mature, is first male and then switches sex to female.
Protein. A molecule consisting of one or more chains of amino acids in a specific order.
Protein polymorphism. Presence of several variants of a protein of a given type (e.g., a certain enzyme, such as carboxylase) in a population.
Proteomics. The study of organism response by assaying cellular protein diversity and abundance.
Protista. Group, sometimes considered a kingdom, of mostly unicellular organisms with a true nucleus and chromosomes. Includes ciliates, flagellates, and some macroalgae. This group is not well defined as an evolutionary group of organisms.
Protogynous. An animal that, when sexually mature, is first female and then switches sex to male.
Protostomes. Individuals belonging to a group of Bilateria, including phyla of ecdysozoans (e.g., Arthropoda) and lophotrochozoans (e.g., Annelida).
Province. A geographically defined area with a characteristic set of species or characteristic percentage representation by given species.
Pseudofeces. Material rejected by suspension feeders or deposit feeders as potential food before entering the gut.
psu. Practical salinity unit. A measure of the salt content of seawater (practical salinity), based upon electrical conductivity of a sample relative to a reference standard of seawater at one atmosphere pressure and 15°C temperature. The reference is a set of diluted seawater samples from the North Atlantic of known salt content. See also ppt.
Pteropods. Group of holoplanktonic gastropods.
Purple sulfur bacteria. A group of bacteria usually living in stagnant water or on stagnant anoxic sediment surfaces as microbial mats that perform photosynthesis and oxidize hydrogen sulfide.
Purines. The bases adenine and guanine in DNA or RNA.
Purse seine. A seine net that is set in a ring and can be reduced in diameter by pulling a line, trapping fish.
Pycnocline. Depth zone within which seawater density changes.
Pycnogonida. A group of crustacea having long, spiderlike legs.
Pyrimidines. The bases cytosine, thymine, and uracil in DNA and RNA.
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Q10 Increase of metabolic rate with an increase of 10ºC
Quantitative genetics. The study of the genetic basis of traits, usually explained in terms of the interaction of a group of genes with the environment
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- The intrinsic rate of increase of a population.
Radial cleavage. A type of cell division in early embryonic growth in which the cleavage plane is parallel or perpendicular to a single embryonic axis.
Radiance. The amount of electromagnetic radiation (e.g., light energy) arriving at a point on the earth’s surface.
Radiocarbon technique (primary productivity). The estimation of primary productivity by the measurement of radiocarbon uptake.
Radiolaria. Protistan phylum whose members are planktonic and secrete an often elaborate siliceous test.
Radiolarian ooze. A deep-sea sediment, composed primarily of radiolarian tests.
Radula. A belt of teeth, found in gastropods and chitons, used for feeding.
Ram feeders. Moving fish that feed by moving rapidly at a prey item with the mouth open.
Random population change. Change in population size over time that has no predictable trend.
Random spatial distribution. Situation in which individuals are randomly distributed in a space; probability of an individual’s being located at any given point is the same irrespective of location in the space.
Rarefaction curve. A relationship between number of species collected as a function of the number of individuals collected. As more and more individuals are collected, the number of species collected will eventually reach a plateau. The relationship of species to individuals can be used to predict the expected number of species at different sample sizes of individuals.
Reaction center. Parts of the cell that include chlorophyll and proteins that receive photon energy during photosynthesis.
Real-time PCR. Method of quantifying the amount of DNA as it is being amplified.
Recruitment. The residue of those larvae that have (1) dispersed, (2) settled at the adult site, (3) made some final movements toward the adult habitat, (4) metamorphosed successfully, and (5) survived to be detected by the observer.
Red tide. A dense outburst of phytoplankton (usually dinoflagellates) often coloring water red-brown.
Redfield ratio. Molecular ratio of carbon, nitrogen, and phosphorus found in phytoplankton.
Redox-potential discontinuity (RPD). That depth below the sediment–water interface marking the transition from chemically oxidative to reducing processes.
Refuge. A device by which an individual can avoid predation.
Regeneration production. Primary production that is caused by nutrients that are recycled within a water body from excretions.
Regulator. An organism that can maintain constant some aspect of its physiology (e.g., body temperature) despite different and changing properties of the external environment.
Remote sensing. Acquisition of environmental data with an instrument that is not in contact with the medium to be sampled, often at great distances, as in satellites sensing the earth’s surface.
Remotely operated vehicle (ROV). An underwater vehicle connected to the ship by a cable, whose movements are directed from shipboard. ROVs may have sensors to measure salinity, temperature, and other variables, but also may have video cameras and sampling devices.
Renewable resource. A resource that can be regenerated (e.g., a growing diatom population that is being exploited by a copepod).
Reproductive effort. The fraction of assimilated nutrients that are devoted to reproductive behavior and gamete production.
Residence time. The time a unit of a substance spends in a specified location in the environment (e.g., the residence time of sodium in the Antarctic bottom water).
Resilience. The capacity of a community or ecosystem to respond to a major disturbance and recover quickly to its former state.
Resolution. The smallest amount of change that an instrument can discriminate. See also Accuracy and Precision.
Resource. A commodity that is required by an organism and is potentially in short supply.
Respiration. Consumption of oxygen in the process of aerobic metabolism.
Respiratory pigment. A molecule, polymer, or other complex adapted to bind and transport oxygen efficiently, usually in a circulatory system (e.g., hemoglobin).
Respiratory quotient. The ratio of moles of carbon dioxide produced to oxygen consumed in respiration.
Respiratory trees. Paired, branching structures emerging from the cloaca of a sea cucumber.
Rete mirabile. A countercurrent exchange structure of capillaries that allows gas uptake in a fish swim bladder.
Retention time. The time a unit of water remains in a water body such as an estuary before being mixed into an outside water body, such as the shelf.
Reverse Bohr effect. Effect that occurs when lactate builds up in the blood of certain invertebrates and pH decreases, increasing the affinity of hemocyanin for oxygen.
Reynolds number (Re) A number that represents the relative importance of viscous forces and inertial forces in a fluid. As Re increases, inertial forces become more important. In seawater, Re increases with increasing water velocity and with the size of the object in the water.
Rhizome system. A system of runners below the sediment surface that allows sea grasses and salt marsh plants to extend coverage of a plant over large areas and permits transfer of nutrients to new areas where shoots can emerge at the sediment surface.
Rights-based management. Declaration of a fishery as a total commodity, divided among current users who are give the right to fish a percentage of a catch, or to sell that right to others.
Rip current. A concentrated rapid current moving offshore from a beach fronting a longshore current.
Ripple marks. Surface sedimentary structure formed by movement of water over the bottom, resulting in cyclical highs and lows in the sediment.
Rise. Bottom of low relief at the base of the continental slope.
RNA. A macromolecule consisting of a chain of nucleotides, whose primary function is protein synthesis.
ROV. See Remotely operated vehicle.
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Salinity. Number of kilograms of dissolved salts in 1 kg of seawater, measured in parts per thousand. Actually this definition stands alongside another definition based on water standards whose electrical conductivities are measured. See also ppt and psu.
Salps. A group of pelagic tunicates (phylum Urochordata), either colonial or solitary, with buccal and atrial siphons on opposite sides of the body.
Salt glands. In mangroves: in some species, glands in the leaves that excrete salts to the leaf surface.
Salt marsh. A coastal habitat consisting of salt-resistant plants residing in an organic-rich sediment accreting toward sea level.
Saprophytic organisms. Organisms that break down and decay organic matter.
Satellite radiometer. A device in a satellite that measures the amount of electromagnetic radiation over a specified range of wavelengths.
Saturated solution. With respect to a given substance that might precipitate from solution: the concentration of dissolved components are at a maximum before precipitation will occur.
SAV. Submerged attached vegetation.
Saxitoxin. A neurotoxin that blocks sodium channels, produced by certain phytoplankton species.
Scaphopoda. Class of the phylum Mollusca with elongate tusk-shaped conical shell.
Scattering. Interaction of particles in the water column with light, resulting in a decline of light energy with depth.
Scavenger. An organism that feeds on dead or decomposing animals or macrophytes.
Schooling. Fish: movement, usually coordinated, in groups.
Scientific method. Organized means of learning about the natural world, using observation, forming of hypotheses, and hypothesis testing.
Scleractinia. Order of coelenterates, usually producing calcareous skeletons with hexameral symmetry.
Scope for activity. The surplus of energy available for activity, such as swimming, beyond that required for maintenance.
Scope for growth. The surplus of energy available for growth beyond that required for maintenance.
Scyphozoa. The true jellyfish, members of the phylum Cnidaria.
Seafloor spreading. The horizontal movement of oceanic crust.
Seamount. A rise from the bottom that is more than 1 km above the sea floor but whose top does not reach the sea surface.
Seastar wasting disease. A disease that has strong effects on multiple species of seastar, often causing a wasting away of tissue.
Seaward. Side of an island that faces the direction of wave action generated either by winds or by currents generated by more indirect forces.
Secondary compounds. Molecules that are manufactured for defense against attack by a predator, parasite, or competitor.
Secondary production. The production of living material per unit area (or volume) per unit time by herbivores. Usually expressed as grams of carbon per square meter per year.
Secondary treatment. Treatment of sewage that encourages breakdown of particulate organic matter but releases dissolved nutrients into the marine environment.
Sedimentation. Deposition of particles and chemical precipitation to form deposits in water.
Seine net. Net placed in the water and pulled along, capturing marine organisms in the mesh.
Self-recruitment. Return of planktonic larvae to the source adult population, facilitated by cyclonic currents and behavior adapted to find a returning flow.
Semelparity. Reproducing only once.
Semidiurnal tide. A tidal cycle of alternating and subequal high and low tide.
Semi-infaunal. Living partially buried within the sediment but partially projecting into the water column.
Sequential hermaphrodite. An individual that sequentially produces male and then female gametes or vice versa.
Sessile. Immobile because of an attachment to a substratum.
Seston. Particulate matter suspended in seawater.
Setules. Chitinous projections from copepod maxillipeds that trap food particles.
Sex. Combining genetic materials from different types, known as sexes, usually in the production of offspring.
Sexual selection. Selection for traits that are involved in mating success, such as visual elements (e.g., color) and combat structures (e.g., antlers of deer).
Shear. A force acting parallel to a linear body.
Shelf-slope break. Line marking a change from the gently inclined continental shelf to the much steeper depth gradient of the continental slope.
Shifting baselines. Concept that our perception of the natural environment may change according to how the environment changes over the generations, resulting in a misperception of what was natural several generations before human degradation.
Shoaling. Attraction of individuals, usually fish, as an aggregation to a shallow water area.
Short-term (acute) effects. Immediate response to an environmental change.
Sibling species. Closely related species that are so similar they are nearly indistinguishable morphologically.
Side-scan sonar. A sonar system producing sound energy that bounces off the seafloor and is subsequently picked up by a detector. The signal gives a picture of the seabed surface, revealing a variety of surface sedimentary features. See also Multibeam sonar.
Sigma. Parameter expressing the seawater density and equal to 1 minus the density of seawater, measured at a given temperature and at a pressure of 1 atmosphere.
Sill. A raised portion of bottom near the mouth of a water body (e.g., a fjord) that connects to the open sea.
Silt–clay fraction. The particle fraction of a sediment that is less than 62 µm in diameter.
Simultaneous hermaphrodite. An individual capable of producing male and female gametes at the same time.
Siphonophores. A group of specialized hydrozoan cnidarians, consisting of large planktonic polymorphic colonies.
Sled. A benthic sampling device designed to slide along the sediment surface, digging into the bottom to a depth of at most a few centimeters.
Slope. A steep-sloping bottom extending seaward from the edge of the continental shelf and downward toward the rise.
Smith–McIntyre grab. A device that collects a bottom sample by means of spring-loaded sections that close together and enclose a sediment sample. See also Grab.
Snow. See Marine snow.
SNPs. Single nucleotide polymorphisms, or polymorphisms at specific sites in a DNA sequence, corresponding to synthesis of a specific nucleotide in a gene.
Soft sediment. Sediment composed of separate sedimentary grains.
Solar irradiance. Solar energy that reaches the ocean or earth surface.
Solubility product constant. At saturation, a constant, which is a multiple of the solubilities of the two ionic components (e.g., Na+ and Cl–) of the substance that could crystallize in solid phase.
Solubility pump. The drawing of carbon to great ocean depths owing to the increased solubility of carbon dioxide in colder deeper waters.
Somatic growth. Growth of the body, exclusive of gametes.
Sorting (of a sediment). The range of scatter of particle sizes about the median grain size of a sediment.
Space limited. Description of a situation in which space is a limiting resource.
Spatial autocorrelation. A situation in which some parameter at any location (e.g., population density) can be predicted through a knowledge of the values of the parameter in other locations.
Spatial distribution. The arrangement of individuals in a space.
Speciation. The process of formation of new species.
Species. A population or group of populations that are in reproductive contact but are reproductively isolated from all other populations
Species richness. The number of species in an area or biological collection.
Species-area effect. A regular logarithmic relationship between the number of species in a confined geographic area (e.g., an island) and the area in which the species occur.
Sperm attractants. Chemicals that sperm use to follow concentration gradients to eggs.
Spicules. Skeletal elements made of silica found in the outer wall of a sponge.
Spillover effect. When a marine no-take area is established, increased population growth within the area might result in resource species moving into an adjacent area, increasing the size of a fishery.
Spongin. The organic material of which the sponge skeleton is composed.
Sporophyte. Diploid stage in the life cycle of a plant.
Spring diatom increase.The major rapid population increase of diatoms, occurring in the spring in temperate-boreal latitudes.
Spring freshet. The increase of flow in an estuary in spring, owing to snow melt and precipitation in the watershed.
Spring tide. The biweekly time, corresponding to full and new moons, of maximum tidal vertical range.
Spur-and-groove topography. Topographic feature of some coral reefs with massive colonies forming an alternation of projections and hollows.
Stability-time hypothesis. Hypothesis that states that higher diversity occurs in habitats that are ancient and stable environmentally.
Standing crop. The amount of living material per unit area or volume; may be expressed as grams of carbon, total dry weight, and so on.
Stern slipway. Large opening in the stern end of a whaling factory ship through which a whale carcass could be dragged onto the ship.
Stipe. In seaweeds: the structure that connects the holdfast to the frond(s) or blades and usually provides mechanical strength to the seaweed in a current.
Stock. A population of a species involved in a fishery whose population dynamics are relatively independent of other stocks (usually geographically separated).
Stock-recruitment model. Fishery model that predicts the amount of juvenile recruitment as a function of the parent stock.
Stokes’ law. Mathematical relationship that describes the terminal settling velocity of small particles through a fluid such as water, taking into account the effect of viscosity.
Stratification. In benthos, the presence of different infaunal species at distinct respective horizons below the sediment–water interface.
Subduction zones. Locations where one crustal plate is dragged down below another and eventually is melted within the mantle.
Submarine canyon. An erosional and linear feature found incised in the continental slope, allowing sediment to rapidly move downward to the base of the slope and the continental rise.
Subtidal zone. The depths below the lowest extent of vertical tidal motion in a benthic environment.
Subtropical. Refers to the portion of the temperate zone closest to the equator.
Succession. A predictable ordering of a dominance of a species or groups of species following the opening of an environment to biological colonization.
Sulfate-reducing bacteria. Bacteria that use sulfate as an oxidizing agent, reducing it to sulfide.
Surface browser. Organism that feeds by scraping thin layers of living organisms from the surface of the substratum (e.g., periwinkles feeding on rock-surface diatom films; urchins scraping a thin, filmy sponge colony from a rock).
Surface layer. The layer of the ocean extending from the surface to a depth above which the ocean is homogeneous due to wind mixing.
Surface mixing hypothesis. Explanation for diurnal vertical migrations of zooplankton, arguing that zoo-plankton go to depth in order to rise to newly mixed surface waters.
Surfactant. A substance that reduces the surface tension between water and various hydrophobic organic compounds (detergent action) and aids in removing these compounds from surfaces. Present in deposit-feeder guts to aid in removing organic compounds from particle surfaces.
Survivorship curve. The curve describing changes of mortality rate as a function of age.
Suspension feeder. An organism that feeds by capturing particles suspended in the water column.
Swarming behavior. Movement of members of a species, usually zooplankton or fish, into a tight aggregation for either protection against predators or for breeding.
Swash rider. Invertebrate that can migrate up and down shore with the rising and falling tide, in order to maintain station at a level that is moist but not overly washed by the waves.
Swim bladder. In fishes, a gas-filled chamber whose volume can be regulated so that fish can regulate their depth.
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Tags. See Implanted tags.
Teleplanic larva. Larva capable of dispersal over long distances, such as across oceans.
Temperate zone. Pertaining to the latitudinal belt between the tropics (23.5° N latitude) and the Arctic or Antarctic Circle (66.5° S latitude), in the Northern and Southern Hemispheres, respectively.
Tentacle-tube-foot suspension feeder. Suspension feeder that traps particles on distinct tentacles or tube feet (in echinoderms).
TEP. See Transparent exopolymers.
Terminal anchor. In hydraulically burrowing organisms: any device used to anchor the leading portion of the burrower, permitting muscular contraction to drag the rest of the body into the sediment.
Territoriality. Defense of a specified location against intruders.
Tertiary production. The production of living material per unit area (or volume) per unit time by organisms consuming the herbivores. Usually expressed as grams of carbon per square meter per year.
Tertiary treatment. Treatment of sewage that removes dissolved nutrients before it enters the environment.
Tethys. An ancient sea that connected the present Indian Ocean with the Mediterranean and Atlantic. The sea was eliminated by a terrestrial uplift in the Miocene.
Thallus. In seaweeds: the life-history form that is usually macroscopic and attaches to a substratum.
Theca (in dinoflagellates). An organic skeleton of dinoflagellates consisting of cellulose plates.
Thermocline. Depth zone within which temperature changes maximally.
Thermohaline circulation. Movement of seawater that is controlled by density differences that are largely explained in terms of temperature and salinity.
Thixotropy. Property of watery sediment in which it liquefies more when a pressure is applied to it.
Tidal current. A water current generated by regularly varying tidal forces.
Tidal wave. See Tsunami.
Tides. Periodic movement of water resulting from gravitational attraction between the earth, sun, and moon.
Time-in-patch model. A model that predicts the optimal time that a forager should exploit a patch of food before moving on to another patch.
Top-down control. Refers to food webs where control of a population is mainly explained by consumption by a species or group of species at higher levels of the food chain (e.g., population change of population of mussels controlled by sea star predation).
Toxic algal blooms. Blooms, usually of phytoplankton, that result in toxic effects on other marine organisms or humans.
Trace elements. Elements in the ocean at an average concentration less than 1 part per million.
Trade winds. Persistent winds at low latitudes in both the Northern and Southern Hemispheres, blowing toward the west and the equator.
Trailing edge population. Population living at the low latitude extreme edge of a species. These populations are believed to be more vulnerable to warming related climate change.
Trait-mediated indirect interaction. A plastic trait, in which a species changes its behavior or morphology depending on the presence of an interacting species (e.g., a predator), which may lead to different interactions within a community. See also Density-mediated indirect interaction.
Transcriptomics. The study of organismic reactions by estimating the degree of gene expression of one or a wide range of genes by assaying RNA content.
Transferrin. Protein in vertebrate blood that binds to iron.
Translation. The process of protein synthesis that determines the amino acid sequence of the protein (primary structure).
Transparent exopolymers (TEP). Large transparent polymers of mainly acidic polysaccharides that enhance aggregation of fine organic particles. TEP are produced mainly by plank-tonic diatoms.
Transverse faults. Large-scale geological faults in oceanic crust.
Trench. Deep and sinuous depression in the ocean floor, usually seaward of a continental margin or an arcuate group of volcanic islands.
Trichomes. Rows of connected cells of cyanobacteria.
Trilobita. Group of extinct arthropods.
Trophic cascade. A strong interaction among trophic levels in a food chain, where changes in density at one level results in indirect effects at a trophic level that does not directly interact with the first level. An example is an increase in carnivores, which indirectly results in the increase in abundance of plants, since herbivores have been reduced.
Trophic group amensalism. Hypothesis of negative effects of deposit feeders in soft sediments on suspension feeders living in the same habitat type.
Trophic level. In a food chain, a level containing organisms of identical feeding habits with respect to the chain (e.g., herbivores).
Trophosome. A part of the body of a vestimentiferan worm that contains symbiotic bacteria.
Tropical. Being within the latitudinal zone bounded by the two tropics of Cancer and Capricorn (23° and ca. 26° N and S latitude).
True jellyfish. Jellyfish belonging to the Cnidarian class Scyphozoa.
Tsunami. A large and fast-traveling ocean wave usually caused by an earthquake or major slide of sediment.
Tube feet. Structures in echinoderms used in locomotion or feeding.
Turbidity. The weight of particulate matter per unit volume of seawater.
Turbulent flow. Movement of water that can be characterized by streamlines moving in a very irregular fashion.
Turtle exclusion device. Device designed to divert turtles from being trapped in a regular fish net.
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Ubiquitin. Protein found in all eukaryotic cells that can remove degrading proteins.
Ultraplankton. Planktonic organisms that are less than 2 µm in size.
Uniform spatial distribution. Situation in which individuals are more evenly spread in space than would be expected on the basis of chance alone.
Upper-canopy kelps. Kelps that extend far above the seafloor and have the potential to shade seaweeds below.
Upwelling. The movement of nutrient-rich water from a specified depth to the surface, usually driven by surface winds.
Urochordata. Deuterostome phylum including sea squirts and salps, with larvae that have characters of chordates.
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Vadose layer. In mangrove forests, a sediment layer with high saltwater content.
Vents. See Hydrothermal vents.
Vertical stratification (in sediment). The occurrence of burrowing species at different levels below the sediment-water interface.
Vertical zonation. The presence of different depth bands dominated by different species in the intertidal zone.
Vertically homogeneous estuary. An estuary in which, at any given location, wind or tidal mixing homogenizes salinity throughout the water column.
Viscosity. As in dynamic viscosity: a measure of the degree that the fluid resists deformation under a force; a measure of “stickiness” of the fluid.
Viscous forces. Forces in a fluid that are explained by viscosity.
Vitamin. Chemical substance required in trace concentrations, acting as a cofactor with enzymes in catalyzing biochemical reactions.
Viviparous. Refers to development of an organism through the juvenile stage within a parent, with live release into the environment.
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Warm-core ring. A blob of water formed by a meander of the Gulf Stream, which encloses even warmer water in the ocean, usually on the continental shelf in summer.
Water mass. A body of water that maintains its identity and can be characterized by such parameters as temperature and salinity.
Water vascular system. A system of tubes in echinoderms used to extend and provide suction to tube feet.
Watershed. The land area that is drained by a river or estuary and its tributaries.
Wave height. The vertical distance from the crest to the trough of a wave.
Wave length. The distance between crests in a system of waves.
Westerlies (prevailing westerlies). Persistent eastward-equatorward winds in midlatitudes in both the Northern and Southern Hemispheres.
White band disease. Coral disease, perhaps caused by a bacterium, that results in an advancing white band in the colony.
White plague. A complex of scleractinian coral diseases, sometimes associated with a coccoid bacterium.
Windward side. The side of an island that faces a persistent wind.
Winkler method. A method for measuring dissolved oxygen in water, using a chemical titration technique.
Within-habitat component. A contrast of diversity between two localities of similar habitat type.
Wrack zone. A bank of accumulated litter at the strandline.
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Year-class effect. The common domination of a species population by individuals recruited in one reproductive season.
Year-size classes. Size groupings in a size-frequency graph that correspond to year classes.
Young-of-the-year. The new year class of an exploited species, formed usually in a restricted reproductive season.
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Zonation. Occurrence of single species or groups of species in recognizable bands that might delineate a range of water depth or a range of height in the intertidal zone.
Zooids. Individuals in a bryozoan colony.
Zooplanktivore. Organism that eats zooplankton.
Zooplankton. Animal members of the plankton.
Zooxanthellae. A group of dinoflagellates living endosymbiotically in association with one of a variety of invertebrate groups (e.g., corals).
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