Glossary of Marine Biology


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Bathypelagic zone. The 2,000 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


Bioluminescence. Light emission, often as flashes, by many marine organisms


Biomass. See Standing crop


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


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.


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


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)