Abiotic Factor:  The physical, chemical and other non-living components of the environment that a . . .
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 sur . . .
Acclimation:  Given a change of a single parameter, a readjustment of the physiology of an org . . .
Accuracy:  Is the correctness of a measure when comparing to a known standard. See also res . . .
Adaptation:  Any change in the structure or function of an organism which makes it better sui . . .
Age Structure:  The relative abundance of different age classes in a population . . .
Aggregated Spatial Distribution:  A case where individuals in a space occu . . .
Ahermatypic:  Non-reef-building (referring to scleractinian corals) . . .
Allele:  One of several variants that can occupy a locus on a chromosome . . .
Allopatric Speciation:  The differentiation of geographically is . . .
Allozyme:  A variant of an enzyme type. These may be variants of a specific enzyme (e.g., c . . .
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 . . .
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 ab . . .
Assortative Mating:  The mating of a given genotype mates with another genotype at a frequency dispro . . .