biota
32
hierarchy. The main objective of biostratigraphy is the correlation of stratigraphical sequences in different areas. Major obstacles to this are lateral
changes in facies. ~stratigraphy and ~micropaleontology.
biota living organisms, e.g., freshwater, marine, terrestrial biota.
biotelemetry ~telemetry.
biotic pertaining to life. Opposite of abiotic. For example: biotic environmental
factors are influences on the structure and functioning of an ecosystem caused
by living organisms, e.g., predation, parasitism, competition for food or
space, bioturbation, shading, etc.
biotin a growth vitamin (H), CIOHI603NzS, of the vitamin-B complex. Occurs
widely in various food products, and is abundant in liver, kidney, yeast, cauliflower, and peas. It is an essential nutrient for various microorganisms and
higher animals. Biotin deficiency in animals is associated with the development of dermatitis, loss of fur, disturbances of the nervous system, and
finally death.
biotope part of the biosphere in which the conditions of life for a population of
living organisms are approximately homogeneous.
biotoxin toxin of biological (natural) origin.
bioturbation a term derived from biological perturbation of soil and sediment
and applied for activities of benthic organisms (macro-, meiobenthos) which
result in reworked sediments. Burrowing worms, Bivalvia and Crustacea often
disturb the sediment structure considerably by mixing and pushing deeper
material upwards (diffusive type of bioturbation). Some deposit-feeders have a
special grain-size selective effect on the sediment composition by deposition of feces (consisting of sediment eaten under the sediment surface) on
the seabed (conveyor-belt type of bioturbation). The feeding activities of
fish, shrimps, and birds can also cause mixing of surface sediment. The
mixing and selection of sediments by bioturbation, together with physical
turbation by currents and waves, strongly affect the exchanges of organic
matter, oxygen, nutrients, microorganisms, etc. between the anaerobic zone,
the aerobic zone and the overlying water. Bioturbation is an important item in
geological studies on sedimentation rates (~ichnofossil). Bioturbation strongly affects the chemical composition of pore waters. The reworking under
marine conditions may have the qualitative extent of a diffusion process
with apparent diffusion coefficients of about 10- 7 to 10- 8 cm z S-1 for sediment reworking and 10-4 cmZ S-1 for pore-water mixing. For comparison,
molecular diffusion in pore waters is only about 3 10-6 cmZ S-I.
32
hierarchy. The main objective of biostratigraphy is the correlation of stratigraphical sequences in different areas. Major obstacles to this are lateral
changes in facies. ~stratigraphy and ~micropaleontology.
biota living organisms, e.g., freshwater, marine, terrestrial biota.
biotelemetry ~telemetry.
biotic pertaining to life. Opposite of abiotic. For example: biotic environmental
factors are influences on the structure and functioning of an ecosystem caused
by living organisms, e.g., predation, parasitism, competition for food or
space, bioturbation, shading, etc.
biotin a growth vitamin (H), CIOHI603NzS, of the vitamin-B complex. Occurs
widely in various food products, and is abundant in liver, kidney, yeast, cauliflower, and peas. It is an essential nutrient for various microorganisms and
higher animals. Biotin deficiency in animals is associated with the development of dermatitis, loss of fur, disturbances of the nervous system, and
finally death.
biotope part of the biosphere in which the conditions of life for a population of
living organisms are approximately homogeneous.
biotoxin toxin of biological (natural) origin.
bioturbation a term derived from biological perturbation of soil and sediment
and applied for activities of benthic organisms (macro-, meiobenthos) which
result in reworked sediments. Burrowing worms, Bivalvia and Crustacea often
disturb the sediment structure considerably by mixing and pushing deeper
material upwards (diffusive type of bioturbation). Some deposit-feeders have a
special grain-size selective effect on the sediment composition by deposition of feces (consisting of sediment eaten under the sediment surface) on
the seabed (conveyor-belt type of bioturbation). The feeding activities of
fish, shrimps, and birds can also cause mixing of surface sediment. The
mixing and selection of sediments by bioturbation, together with physical
turbation by currents and waves, strongly affect the exchanges of organic
matter, oxygen, nutrients, microorganisms, etc. between the anaerobic zone,
the aerobic zone and the overlying water. Bioturbation is an important item in
geological studies on sedimentation rates (~ichnofossil). Bioturbation strongly affects the chemical composition of pore waters. The reworking under
marine conditions may have the qualitative extent of a diffusion process
with apparent diffusion coefficients of about 10- 7 to 10- 8 cm z S-1 for sediment reworking and 10-4 cmZ S-1 for pore-water mixing. For comparison,
molecular diffusion in pore waters is only about 3 10-6 cmZ S-I.