Glossary / Science

Marine Biology Glossary

Abiotic Factor: The physical, chemical and other non-living components of the environment that an organism lives in.
Abyssal Plain: The deep ocean floor, an expanse of low relief at depths of 4,000 to 6,000 m
Abyssopelagic Zone: 'Abysso' meaning 'no bottom', this zone of the ocean begins 4000 m below the surface of the ocean an
Acclimation: Given a change of a single parameter, a readjustment of the physiology of an organism, reaching a ne
Accuracy: Is the correctness of a measure when comparing to a known standard. See also resolution and precisio
Adaptation: Any change in the structure or function of an organism which makes it better suited to its environme
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)
Allele: One of several variants that can occupy a locus on a chromosome
Allele: One of the alternative forms of a particular gene. Each gene is comprised of two alleles, one inheri
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 ar
Amensal: Negatively affecting one or several species
Amino Acids: Basic structural unit of proteins
Anadromous Fish: Fish that spends most of its life feeding in the open ocean but that migrates to spawn in fresh wate
Anoxic: Lacking oxygen.
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 e
Atoll: A horseshoe or circular array of islands, capping a coral reef system perched around an oceanic volc
Attenuation (Of Light): Diminution of light intensity; explained, in the ocean, in terms of absorption and scattering
Autotroph: An organism that synthesizes organic molecules from inorganic starting materials through photosynthe
Auxotrophic Algae: Algae requiring a few organically derived substances, such as vitamins, along with dissolved inorgan
Bathypelagic Zone: The zone of the ocean that extends from 1000m to 4000m below the surface of the ocean. Visit the Bat
Benthic: Refers to organisms that live on or in the ocean bed. Benthic epifauna are organisms that live on th
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, s
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)
Bioaccumulation: The process whereby pollutants are taken up, retained and concentrated in the cells of plants and an
Biodiversity: See species richness
Biodiversity: The variation in life on Earth reflected at all levels, from various ecosystems and species, to the
Biogenic Graded Bedding: A regular change of sediment median grain size with depth below the sediment-water interface caused
Biogenically Reworked Zone: The depth zone, within a sediment, that is actively burrowed by benthic organisms
Bioluminescence: Light emission, often as flashes, by many marine organisms
Bioluminescence: Meaning living (bio) light (luminescence) is the light produced by living organisms and the emission
Biomass: See Standing crop
Biotic Factor: A living component of the environment which arises from and affects living organisms (distinct from
Blood Pigment: A molecule used by an organism to transport oxygen efficiently, usually in a circulatory system (e.g
Bloom (Phytoplankton): A population burst of phytoplankton that remains within a defined part of the water column
Bohr Effect: When blood ph decreases, the ability of hemoglobin to bind to oxygen decreases. An adaptation to rel
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., con
Boundary Layer: A layer of fluid near a surface, where flow is affected by viscous properties of the fluid. At the s
Brackish Sea: Semienclosed water body of large extent in which tidal stirring and seaward flow of freshwater do no
Browsers: Organisms that feed by scraping thin layers of living organisms from the surface of the substratum (
Calcareous: Made of calcium carbonate
Carnivore: An organism that captures and consumes animals
Carrying Capacity: The total number of individuals of a population that a given environment can sustain
Catadromous Fish: Fish that spawns in seawater but feed and spends most of its life in estuarine or fresh water
Chaetognaths: See Arrowworms
Character Displacement: A pattern in which two species with overlapping ecological requirements differ more when they co-occ
Chemosynthesis: Primary production of organic matter, using various substances instead of light as an energy source;
Chemosynthesis: The process whereby chemical energy is used to make organic compounds from inorganic compounds. One
Chlorinity: Grams of chloride ions per 1000 grams of seawater
Chloroplast: In eukaryotic organisms, the cellular organelle in which photosynthesis takes place
Chromosome: A linear sequence of genes wound up with proteins into a single unit that is found in the nucleus of
Cladogram: A tree-like diagram showing evolutionary relationships. Any two branch tips sharing the same immedia
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
Community: A naturally occurring group of plants and animals that live within a certain environment and interac
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
Competition: An interaction between or among two or more individuals or species in which exploitation of resource
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 identical
Conservation Biology: A field of science that deals with threats to biodiversity. The goals of conservation biology are to
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 bre
Convergence: The contact at the sea surface between two water masses converging, one plunging below the other
Convergent Evolution: The development of similar structures in organisms that do not share recent common ancestor (e.g. Ey
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 her
Corer: Tubular benthic sampling device that is plunged into the bottom in order to obtain a vertically orie
Coriolis Effect: The deflection of air or water bodies, relative to the solid earth beneath, as a result of the earth
Counter-Illumination: Having bioluminescent organs that are concentrated on the ventral surface so as to increase the effe
Countercurrent Exchange Mechanism: Mechanism by which two vessels are set side by side, with fluid flowing in opposite directions, allo
Countershading: Condition of organisms in the water column that are dark-colored on top but light-colored on the bot
Critical Depth: That depth above which total integrated photosynthetic rate equals total integrated respiration of p
Critical Salinity: A salinity of approximately 5 to 8% that marks a minimum of species richness in an estuarine system
Cryptic Colouration: To protect themselves against predators, many animals acquire colouring and markings to match and co
Ctenophora: See Comb jellies
Daily Estuary: An estuary in which tidal movements cause substantial changes in salinity at any one location on a d
Decomposer: An organism which gains energy by breaking down the final remains of living things. Predominantly ba
Decomposition: The biochemical process where biological materials are broken down into smaller particles and eventu
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 fishe
Demographic: Referring to numerical characteristics of a population (e.g., population size, age structure)
Density: (seawater) Grams of sea water per milliliter of fluid
Density-Dependent Factors: Factors, such as resource availability, that vary with population density
Deoxyribonucleic acid (DNA): The primary genetic material of a cell that makes up genes and chromosomes. See also genes, chromoso
Deposit Feeder: An organism that derives its nutrition by consuming some fraction of a soft sediment
Detritus: Particulate material that enters into a marine or aquatic system. If derived from decaying organic m
Detrivore: An organism that feeds on large bits of dead and decaying organic matter. What detrivores leave behi
Diatom: Dominant planktonic algal form with siliceous test, occurring as a single cell or as a chain of cell
Diffusion: The net movement of units of a substance from areas of higher concentration to areas of lower concen
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
Directional Selection: Preferential change in a population, favoring the increase in frequency of one allele over another
Dissolved Organic Matter: Dissolved molecules derived from degradation of dead organisms or excretion of molecules synthesized
Disturbance: A rapid change in an environment that greatly alters a previously persistent biological community
Divergent Evolution: The evolution of one species to a number of different forms. Compare convergent evolution; see also
Diversity: A parameter describing, in combination, the species richness and evenness of a collection of species
Diversity Gradient: A regular change in diversity correlated with a geographic space or gradient of some environmental f
Ecological Niche: The role a plant or animal plays in its community. The niche of an organism is defined by what it ea
Ecology: The study of the physical and biological interactions between an organism and its natural environmen
Ecosystem: A community of plants, animals and other organisms that are linked by energy and nutrient flows and
Ecosystem Diversity: The diversity of biological communities and their physical environment. Diversity is determined by t
Effluent: Industrial or urban waste discharged into the environment.
Ekman Circulation: 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 incre
Emigration: The departure of individuals from a given area
Endangered: A species or ecosystem that is so reduced or delicate that it is threatened with or on the verge of
Endemic: An animal or plant species that naturally occurs in only one area.
Endosymbiotic: Being symbiotic and living within the body of an individual of the associated species
Environment: All of the physical, chemical, and biological factors in the area where a plant or animal lives.
Environmental Stress: Variously defined as (a) an environmental change to which an organism cannot acclimate and (b) an en
Epibenthic: Living on the surface of the bottom
Epidemic Spawning: Simultaneous shedding of gametes by a large number of individuals
Epifaunal: Living on the surface of the bottom
Epifloral: Living on the surface of the bottom
Epilithic: A term for organisms that live attached to rocks. Latin translation: epi = upon, lith = rock. This t
Epipelagic Zone: The 0- to 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 -alinity layer
Estuarine Realms: Large coastal water regions that have geographic continuity,are bounded landward by a stretch of coa
Estuary: A semienclosed body of water that has a free connection with the open sea and within which seawater
Euphausiid: Member of an order of holoplanktonic crustacea
Eutrophic: Water bodies or habitats having high concentrations of nutrients
Eutrophication: Enrichment of a water body with nutrients, resulting in excessive growth of phytoplankton, seaweeds,
Evenness: The component of diversity accounting for the degree to which all species are equal in abundance, as
Evolution: The process by which a species' structural and behavioural characteristics change over many generati
Extinct: A species which no longer exists. The Stellar sea cow is an example of a species which once lived on
Extirpated: A species no longer existing in Canada, but occurring elsewhere on Earth. Compare extinct.
Fecal Coliform Bacteria: Technically, all the facultative anaerobic gram negative non-spore forming rod shaped bacteria that
Fecal Pellets: See Pellets
Fecundity: The number of eggs produced per female per unit time (often: per spawning season)
Fertilization: The joining or fusion of the male gamete (sperm) and the female gamete (egg) to form a zygote during
Foliose Coral: A coral whose skeletal form approximates that of a broad, flattened plate
Food Chain: A linear sequence of organisms that exist on successive trophic levels within a natural community, t
Food Chain Efficiency: Amount of energy of some other quantity extracted from a trophic level, divided by the amount of ene
Food Web: A non-linear network of feeding between organisms that includes many food chains, and hence multiple
Foraminifera: Protozoan group, individuals of which usually secrete a calcareous test; both planktonic and benthic
Founder Principle: A small colonizing population is genetically unrepresentative of the source of population
Freshet: An increase of water flow into an estuary during the late winter or spring, owing to increased preci
Front: A major discontinuity separating ocean currents and water masses in any combination
Fugitive Species: A species adapted to colonize newly disturbed habitats
Gamete: A mature reproductive cell that is capable of fusing with another gamete of the opposite sex to form
Gametophyte: Haploid stage in the life cycle of a plant
Generalist: A species that can live in many different habitats and can feed on a number of different organisms.
Generation Time: The time period from birth to average age of reproduction
Genes: The hereditary material coded in cells that determine how an organism will look and behave. A gene i
Genetic Diversity: The genetic variation that occurs within a population or species. For example, there are several dif
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
Genetic Polymorphism: Presence of several genetically controlled variants in a population
Genotype: The genetic makeup of an organism, with respect to a given genetic locus, the alleles it carries
Genotype: The genetic makeup of an organism. The actual appearance of an individual (the phenotype) depends on
Genus: (plural: genera) The level of the taxonomic hierarchy above the species but below the family level
Geographic Information System (GIS): A system that allows automatic location of information suitable for mapping. Usually involves a soft
Geostrophic Flow: Movement of water in the oceans as a combined response to the Coriolis effect and gravitational forc
Geotactic: Moving in response to the earth's gravitational field
Gillnet: A net set upright in the water to catch fish by entangling their gills in its mesh.
Global Warming: Predicted increase in the earth's oceanic and atmospheric temperature, owing to additions of carbon
Gps. Global Positioning System: An electronic device that uses positioning signals from satellites in order to locate precisely lati
Grab: Benthic sampling device with two or more curved metal plates designed to converge when the sampler h
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.
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
Guild: A group of species, possibly unrelated taxonomically, that exploit overlapping resources
Gyre: Major cyclonic surface current systems in the oceans
Habitat: The immediate space where an animal or plant lives and has food, water and protection. Habitat loss,
Halocline: Depth zone within which salinity changes maximally
Hardy-Weinberg Law: Law that states that the frequencies of genotypes in a population at a locus are determined by rando
Harmful Algal Bloom: A bloom of (usually) planktonic microalgae belonging to a strain of a species that has a toxic harmf
Herbivore: An organism that consumes plants
Herbivore: A plant-eating animal. Sea urchins re a good example of a marine herbivore as they feed on kelp. See
Heritable Character: A morphological character whose given state can be explained partially in terms of the genotype of t
Hermaphrodite: An individual capable of producing both eggs and sperm during its lifetime
Hermaphrodite: An animal that has both male and female reproductive organs. Nudibranchs (sea slugs) are a good exam
Hermatypic: Reef-building
Heterotroph: An organism that is unable to synthesize organic compounds (and thus its energy) from the environmen
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 lay
Histogram: A multiple-bar diagram representing the frequency distribution of a group as a function of some vari
Holoplankton: Organisms spending all their life in the water column and not on or in the sea bed
Homeotherm: An organism that regulates its body temperature despite changes in the external environmental temper
Homogeneous: Similar or uniform structure or composition throughout.
Homozygote: With respect to a given genetic locus, a diploid individual carrying two identical alleles
Hydrographic: Referring to the arrangement and movement of bodies of water, such as currents and water masses
Hydrothermal Vents: Sites in the deep ocean floor where hot, sulfur-rich water is released from geothermally heated rock
Hypothesis: A refutable statement about one or a series of phenomena
Infaunal: Living within a soft sediment and being large enough to displace sedimentary grains
Inorganic: Part of or derived from non-biological material. A chemical compound that does not include a carbon
Interspecific Competition: Condition in which one species' exploitation of a limiting resource negatively affects another speci
Interstitial: Living in the pore spaces among sedimentary grains in a soft sediment
Introduced Species: An organism that has been brought into an area, usually by humans, where it does not normally occur.
Invasive Species: An introduced species that out-competes native species for space and resources. Scotch Broom is an i
Isotonic: Having the same overall concentration of dissolved substances as a given reference solution
Keystone Predator: The dominant predator or the top predator that has a major influence on community structure. For exa
Keystone Species: A predator at the top of a food web, or discrete subweb, capable of consuming organisms of more than
Laminar Flow: The movement of a fluid where movement of the entire fluid is regular and with parallel streamlines.
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
Ld50: The value of a given experimental variable required to cause 50% 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: The side of an island opposite from the one facing a persistent wind
Life Table: A table summarizing statistics of a population, such as survival and reproduction, all broken down a
Litter: Accumulations of dead leaves in various states of fragmentation and decomposition
Locus: See Genetic locus
Logistic Population Growth: Population growth that is modulated by the population size relative to carrying capacity. Population
Longshore Current: A current moving parallel to a shoreline
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 micrometers in size.
Mainstream Flow: The flow in a part of the fluid (e.g., in a tidal creek) that is well above the bottom or well away
Mangel: See Mangrove forest.
Mangrove Forest: A shoreline ecosystem dominated by mangrove trees, with associated mud flats.
Marine Protected Area: A conservation geographic unit designed to protect crucial communities and to provide reproductive r
Marine Snow: Fragile organic aggregates, resulting from the collision of dissolved organic molecules or from the
Maximum Sustainable Yield: In fisheries biology, the maximum catch obtainable per unit time under the appropriate fishing rate
Megaplankton: Planktonic organisms that are greater than or equal to 2000 micrometers in size
Meiobenthos: Benthic organisms (animals or plants) whose shortest dimension is less than 0.5 mm but greater than
Meiofauna: Animals whose shortest dimension is less than 0.5 mm but greater than or equal to 0.1 mm
Meioflora: Benthic organisms (animals or plants) whose shortest dimension is less than 0.5 mm but greater than
Meroplankton: Organisms that spend part of their time in the plankton but also spend time in the benthos (e.g., pl
Mesopelagic: The 150 -- 2000 m depth zone, seaward of the shelf-slope break
Mesopelagic Zone: Also called the 'twilight zone' of the ocean, this area from 200m to 1000m in depth, is bordered by
Metabolic Rate: The overall rate of biochemical reactions in an organism. Often estimated by rate of oxygen consumpt
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
Microbenthos: Benthic organisms (animals or plants) whose shortest dimension is less than 0.1 mm
Microfauna: Animals whose shortest dimension is less than 0.1 mm
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 ca
Moderately Stratified Estuary: An estuary in which seaward flow of surface low-salinity water and moderate vertical mixing result i
Monophyletic: Refers to a group of species that all have a single common ancestral species
Morphology: The form and structure of an organism, in particular its outside features.
Mucous-Bag Suspension Feeder: Suspension feeder employing a sheet or bag of mucus to trap particles nonselectively
Mutualism: An interaction between two species in which both derive some benefit
Mutualistic: Conferring reciprocal benefit to individuals of two different associated species
Nanoplankton: Planktonic organisms that are 2-20 micometers in size.
Native Species: A species that occurs naturally in an area (i.e. Is not introduced). Compare introduced species, inv
Natural Selection: The main mechanism of evolutionary change. In a given population of organisms, there are heritable t
Neap Tides: Tides occurring when the vertical range is minimal
Nekton: Organisms with swimming abilities that permit them to move actively through the water column and to
Nekton: Pelagic organisms that are free-swimming and so whose movements are independent of the tides, curren
Neritic: Seawater environments landward of the shelf-slope break
Net Primary Productivity: Total primary production, minus the amount consumed in respiration
Neuston: Planktonic organisms associated with the air-water interface.
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
Nitrogen Fixation: The conversion of gaseous nitrogen to nitrate by specialized bacteria.
No-Take Reserves: Geographic areas where by law no one is allowed to fish or collect biological specimens. Rules could
Nonrenewable Resource: A resource that is in limited supply and can't be replenished by natural processes, at least not for
Nuisance Bloom: A rapid increase of one or only a few species of phytoplankton, resulting in densities high enough t
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 i
Oceanic: Associated with sea-water environments seaward of the shelf-slope break
Oceanic Ridge: A sinuous ridge rising from the deep-sea floor
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 herbivo
Optimal Foraging Theory: A theory designed to predict the foraging behavior that maximizes food intake per unit time
Organic: Part of or derived from living organisms. Or a chemical compound that contains carbon as an essentia
Organic Nutrients: Nutrients in the form of molecules synthesized by or originating from other organisms
Osmoconformer: An organism whose body fluids change directly with a change in the concentrations of dissolved ions
Osmoregulator: An organism that regulates the concentration of dissolved ions in its body fluids irrespective of ch
Osmosis: The movement of pure water across a membrane from a compartment with relatively low dissolved ions t
Outwelling: The outflow of nutrients from an estuary or salt-marsh system to shelf waters
Over-Consumption: The use of resources at a rate that exceeds the ability of natural processes to replace them.
Overdominance: Selection favoring heterozygotes
Oxygen Dissociation Curve: A curve showing the percent saturation of a blood pigment, such as hemoglobin, as a function of oxyg
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
Parapatric Speciation: The differentiation into distinct species of populations experiencing some gene flow
Parasite: An organism living on or in, and negatively affecting, another organism
Particulate Organic Matter: Particulate material in the sea derived from the decomposition of the nonmineral constituents of liv
Patchiness: A condition in which organisms occur in aggregations
Pelagic: Refers to the plants and animals that live in the water column or in the open waters of the ocean ra
Pellets: Compacted aggregations of particles resulting either from egestion (fecal pellets) or from burrow-co
Penetration Anchor: In hydraulically burrowing organisms, any device used to penetrate and gain an initial purchase on t
Peptides: Chains of amino acids; often portions of a protein molecule
Pesticides: Chemical products used to reduce or eliminate unwanted organisms, regarded as 'pests'. Pesticides ar
Ph: Measure of he acidity or basicity of water (-log10 of the activity of hydrogen ions in water)
Phenotype: The physical appearance of an individual that is the result of that individual's genotype and the in
Phenotypic Plasticity: The capacity of an individual to produce different phenotypes under different conditions. Non-geneti
Phi Scale: Scale used for measuring the grain size of sediments. = -log2 (grain diameter)
Phosphoresence: See Bioluminescence.
Photic Zone: The surface layer of the ocean that is penetrated by sunlight. The photic zone is the layer of the o
Photorespiration: Enhanced respiration of plants in the light relative to dark respiration
Photosynthate: A substance synthesized in the process of photosynthesis
Photosynthesis: A chemical process whereby plants and algae use a sun's energy to make sugars (organic compounds) fr
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
Phototactic: Moving in response to light
Phylum: The broadest classification for animals. Compare species.
Physiological Race: A geographically defined population of a species that is physiologically distinct from other populat
Phytoplankton: The plant and algae component of the plankton; the primary producers of almost all marine food webs.
Planktivorous: Feeding on planktonic organisms
Plankton: Pelagic organisms that float through the water column, not attached to any substrate and unable to m
Planktotrophic Larva: Planktonic-dispersing larva that derives its nourishment by feeding in the plankton
Planula: The planktonic larval form produced by scleractinian corals and coelenterates
Plate: Major section of the earth's crust, bounded by such features as mid-ocean ridges
Pleistocene: Period of time, going back to approximately 2 million years before the present, in which alternating
Pleuston: Refers to plankton that have a float protruding above the sea surface, such as the Portugese man-of-
Poikilotherm: An organism whose body temperature is identical to that of the external environment
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
Population: The number of individuals of a particular species that live within a defined area.
Population Density: Number of individuals per unit area or volume
Porifera: The phylum comprising the sponges.
PPT: A measure of the salt content of sea water in terms of kg salt per kg of water, reckoned in parts pe
Practical Salinity: See PSU
Practical Salinity Units (PSU): A measure of the salt content of seawater (practical salinity), based upon electrical conductivity o
Precision: Precision is the repeatability of a measurement. A measurement can be precise, but not accurate. See
Predation: The consumption of one organism by another
Predator: An organism that consumes another living organism (carnivores and herbivores are both predators by t
Prey: An animal that is used by other animals for food.
Primary Consumer: A heterotrophic, herbivorous organism that feeds directly on a primary producer. Urchins are a prima
Primary Production: The production of living matter by photosynthesizing organisms or by chemosynthesizing organisms. Us
Primary Production: Synthesis of organic matter by plants, which is the main source of energy and nutrition for other co
Protein Polymorphism: Presence of several variants of a protein of a given type (e.g., a certain enzyme, such as carboxyla
Province: A geographically defined area with a characteristic set of species or characteristic percentage repr
Pseudofeces: Material rejected by suspension feeders or deposit feeders as potential food before entering the gut
Pteropods: Group of holoplanktonic gastropods
Pycnocline: Depth zone within which sea-water density changes maximally
Q10: Increase of metabolic rate with an increase of 10ºc
Quadrat: An ecological sampling unit that consists of a square frame of known area. The quadrat is used for q
Quantitative Genetics: The study of the genetic basis of traits, usually explained in terms of the interaction of a group o
R: The intrinsic rate of increase of a population
Radiocarbon Technique: 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
Radula: A belt of teeth, found in gastropods and chitons. Used for feeding.
Random Spatial Distribution: Situation in which individuals are randomly distributed in a space; probability of an individual's b
Recruitment: The residue of those larvae that have: (1) dispersed; (2) settled at the adult site; (3) made some f
Red Tide: A dense outburst of phytoplankton (usually dinoflagellates) often coloring water red brown
Redox-Potential Discontinuity: That depth below the sediment-water interface marking the transition from chemically oxidative to re
Refuge: A device by which an individual can avoid predation
Regulator: An organism that can maintain constant some aspect of its physiology (e.g., body temperature) consta
Renewable Resource: A resource that can be replenished through natural processes within a human life span, if it is soun
Reproductive Effort: The fraction of assimilated nutrients that are devoted to reproductive behavior and gamete productio
Resolution: The smallest amount of change that an instrument can discriminate. See 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
Respiratory Quotient: The ratio of moles of carbon dioxide produced to oxygen consumed in respiration
Rete Mirabile: A countercurrent exchange structure of capillaries that allows gas uptake in a fish swim bladder
Reverse Bohr Effect: Effect that occurs when lactate builds up in the blood of certain invertebrates and ph decreases, in
Reynolds Number: A number that represents the relative importance of viscous forces and inertial forces in a fluid. A
Rip Current: A concentrated rapid current moving offshore from a beach fronting a longshore current
Rise: Bottom of low relief at the base of the continental slope
Rov: Abbreviation for remotely operated vehicle, usually a submersible tethered to a ship, with facilitie
Salinity: Number of kg of dissolved salts in one kg g of seawater, measured in parts per thousand. Actually th
Salps: A group of pelagic tunicates (phylum Urochordata), either colonial or solitary, with buccal and atri
Salt Marsh: A coastal habitat consisting of salt-resistant plants residing in an organic-rich sediment accreting
Scavenger: An organism that feeds on dead or decomposing animals or macrophytes
Scleractinia: Order of coelenterates, usually producing calcareous skeletons with hexameral symmetry
Scope For Growth: The surplus of energy available for growth beyond that required for maintenance
Scyphozoa: The true jellyfish, members of the phylum Cnidaria
Sea-Floor Spreading: The horizontal movement of oceanic crust
Seasonal Estuary: An estuary in which salinity at any one geographic point changes seasonally (e.g., decreases during
Seaward: Side of an island that faces the direction of wave action generated either by winds or by currents g
Secondary Consumer: A heterotrophic, carnivorous organism that feeds on a primary consumer. Herring feeding on zooplankt
Secondary Production: The production of living material per unit area (or volume) per unit time by herbivores. Usually exp
Selection: A change in allele frequency over time in a population
Selection Pressure: A measure of the effectiveness of natural selection in altering the genetic composition of a populat
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
Shelf-Slope Break: Line marking a change from the gently inclined continental shelf to the much steeper depth gradient
Sibling Species: Closely related species that are so similar that they are nearly indistinguishable morphologically
Sigma: Parameter expressing the seawater density: and equal to 1 minus the density of seawater, measured at
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
Slope: A steep-sloping bottom extending seaward from the edge of the continental shelf and downward toward
Snow: See marine snow
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 thro
Spatial Distribution: The arrangement of individuals in a space
Specialist: A species with a very narrow range in habitat or food requirements. For example, the Marbled Murrele
Speciation: The process of formation of new species
Species: A group of organisms that differ from all other groups of organisms and that are capable of breeding
Species Abundance: The total number of individual of a species within a given area or community. Compare species richne
Species Diversity: A measure of both species abundance and species richness. An area that has a large number of species
Species Richness: The number of different species that exist within a given area or community. Compare species abundan
Species-Area Effect: A regular logarithmic relationship between the number of species in a confined geographic area (e.g.
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 latitude
Spring Tides: Fortnightly tides occurring when the vertical tidal range is maximal
Stability-Time Hypothesis: Hypothesis that states that higher diversity occurs in habitats that are ancient and stable environm
Standing Crop: The amount of living material per unit area or volume; may be expressed as grams of carbon, total dr
Stock Recruitment Models: Fishery models that predict the amount of juvenile recruitment as a function of the parent stock
Stratification: In benthos, the presence of different infaunal species at distinct respective horizons below the sed
Substrate: The material upon or within which a plant or animal live or grows (e.g. Rocky or sandy substrate). S
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
Sunlight Zone: See Photic Zone.
Surface Layer: The layer of the ocean extending from the surface to a depth above which the ocean is homogeneous du
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
Sustainable: A sustainable way of life is one in which human needs are met without diminishing the ability of oth
Swash Rider: Invertebrate that can migrate up and down shore with the rising and falling tide, in order to mainta
Symbiosis: An interaction between two different species where either both, one or neither of the organisms bene
Systematics: The area of biology that deals with the diversity of living organisms, their relationships to each o
Taxonomy: The theory and practice of describing, naming and classifying plants and animals. See also systemati
Teleplanic Larva: Larva capable of dispersal over long distances, such as across oceans
Temperate: Pertaining to the latitudinal belt between 23º 27' and 66º 33' north or south latitude
Tentacle-Tube-Foot Suspension Feeder: Suspension feeder that traps particles on distinct tentacles or tube feet (in echinoderms)
Terminal Anchor: In hydraulically burrowing organisms: any device used to anchor the leading portion of the burrower,
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
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 o
Threatened: A species likely to become endangered if limiting factors are not reversed. Compare endangered, exti
Tidal Current: A water current generated by regularly varying tidal forces
Tides: Periodic movement of water resulting from gravitational attraction between the earth, sun, and moon
Top-Down Control: Refers to food webs where control of a population is mainly explained by consumption by a species or
Trade Winds: Persistent winds at low latitudes in both the Northern and Southern hemispheres, blowing toward the
Transect: A straight line placed on the ground along which ecological measurements are taken. If an ecologist
Trench: Deep and sinuous depression in the ocean floor, usually seaward of a continental margin or an arcuat
Trophic Level: In a food chain, a level containing organisms of identical feeding habits with respect to the chain
Trophic Levels: The energy levels or steps in a food chain or food web: primary producer, primary consumer, secondar
Tropical: Being within the latitudinal zone bounded by the two tropics (23º 27' north and south latitude)
Turbidity: The weight of particulate matter per unit volume of sea water
Twilight Zone: See Mesopelagic Zone.
Ultraplankton: Planktonic organisms that are less than 2 micrometers in size
Uniform Spatial Distribution: Situation in which individuals are more evenly spread in space than would be expected on the basis o
Upwelling: The movement of nutrient-rich water from a specified depth to the surface
Vents: See Hydrothermal vents
Vertically Homogeneous Estuary: An estuary in which, at any given location, wind or tidal mixing homogenizes salinity throughout the
Vitamin: Chemical substances required in trace concentrations acting as a cofactor with enzymes in catalyzing
Viviparous (Development): Refers to development of an organism through the juvenile stage within a parent
Vulnerable: A species of special concern because of characteristics that make it particularly sensitive to human
Wash Zone: The depth zone in which sediments are disturbed by wave action near the shoreline
Water Cycle: The continuous circulation of water from the atmosphere to the earth, including the ocean, and back
Water Mass: A body of water that maintains its identity and can be characterized by such parameters as temperatu
Watershed: The land area that is drained by a river or estuary and its tributaries
Westerlies (Prevailing Westerlies): Persistent eastward-equatorward winds in midlatitudes in both the Northern and Southern Hemispheres
Windward [Side]: The side of an island that faces a persistent wind
Within-Habitat Comparison: A contrast of diversity between two localities of similar habitat type
Wrack Zone: A bank of accumulated litter at the strandline
Year-Class Effect: The common domination of a species population by individuals recruited in one reproductive season
Zonation: Occurrence of single species or groups of species in recognizable bands that might delineate a range
Zooplankton: Animal members of the plankton
Zooplankton: Animal component of the plankton that feed on phytoplankton and other zooplankton (primary consumers
Zooxanthellae: A group of dinoflagellates living endosymbiotically in association with one of a variety of inverteb
Zygote: A fertilized egg. Or the diploid cell that results from the joining of two haploid gametes (sperm an

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