Science / Marine Biology Glossary

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 oxygen concentration of the fluid

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 living organisms

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 rather than the ocean floor (see benthic). Life is found throughout the pelagic zone, howeve . . . View Full Definition

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

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 are often used on gardens, agricultural land, roadsides, and golf courses to eliminate speci . . . View Full Definition

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 interaction of the genotype with the environment during development. Hence, individuals with . . . View Full Definition

Phenotypic Plasticity: The capacity of an individual to produce different phenotypes under different conditions. Non-genetic potential variability within the range of a single individual.

Phi Scale: Scale used for measuring the grain size of sediments. = -log2 (grain diameter)

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