Aspects of Eco-Physiological Adaptations in Antarctic
Fish
Andreas P. A. Wohnnann
Institut flir Polar6kologie, Wischhofstr. 1-3, Gebaude 12, University of Kiel,
24148 Kiel, Germany
Introduction
Antarctic marine ectotherms are highly specialized to cold stenothermic
conditions. At low temperatures, the rates of molecular diffusion and
enzyme reactions can slow down considerably, and in absence of
compensating mechanisms, physiological processes in Antarctic
ectothermes ought to proceed more slowly than in specimens of temperate
or tropical environments [1]. Organisms exhibit a diversity in lipid
structures to fashion membranes to prevailing ambient temperatures in
such a manner that they become more fluid in a cold-acclimatized state
than in a warm-acclimatized state [2].
Higher amounts of unsaturated phospholipid classes increase the fluidity
and hence proper functioning of biomembranes at temperatures close to
freezing. Exposure to low temperatures also requires biochemical and
neurophysiological adjustments protecting biomembranes from freezing.
Higher proportions of polyunsaturated fatty acids [3] as well as alterations
in the composition of gangliosides [4] may contribute to a proper
functioning of the nervous system and brain at freezing temperatures.
In addition to low temperature the continual presence of ice in subzero
water presents fishes with another physiological challenge. The presence
of antifreeze peptides (AFP) and glycopeptides (AFGP) is one important
adaptation for survival in freezing sea-water. Because of this Antarctic
fishes tend to occupy most ecological niches of the Antarctic Ocean
including the surface and midwaters which are often rich in food and also
permanently ice-laden (for review see Clarke [5] and Eastman [6]).
Thus, the objective of my communication is to present a comprehensive
data set on several biochemical adaptations of notothenioids to life in
high-Antarctic waters with special regard to fully pelagic Pleuragramma
antarcticum [7], benthopelagic Trematomus eulepidotus [8] and to the
seasonality of some of the biochemical processes.
G. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag ltalia 1998
Fish
Andreas P. A. Wohnnann
Institut flir Polar6kologie, Wischhofstr. 1-3, Gebaude 12, University of Kiel,
24148 Kiel, Germany
Introduction
Antarctic marine ectotherms are highly specialized to cold stenothermic
conditions. At low temperatures, the rates of molecular diffusion and
enzyme reactions can slow down considerably, and in absence of
compensating mechanisms, physiological processes in Antarctic
ectothermes ought to proceed more slowly than in specimens of temperate
or tropical environments [1]. Organisms exhibit a diversity in lipid
structures to fashion membranes to prevailing ambient temperatures in
such a manner that they become more fluid in a cold-acclimatized state
than in a warm-acclimatized state [2].
Higher amounts of unsaturated phospholipid classes increase the fluidity
and hence proper functioning of biomembranes at temperatures close to
freezing. Exposure to low temperatures also requires biochemical and
neurophysiological adjustments protecting biomembranes from freezing.
Higher proportions of polyunsaturated fatty acids [3] as well as alterations
in the composition of gangliosides [4] may contribute to a proper
functioning of the nervous system and brain at freezing temperatures.
In addition to low temperature the continual presence of ice in subzero
water presents fishes with another physiological challenge. The presence
of antifreeze peptides (AFP) and glycopeptides (AFGP) is one important
adaptation for survival in freezing sea-water. Because of this Antarctic
fishes tend to occupy most ecological niches of the Antarctic Ocean
including the surface and midwaters which are often rich in food and also
permanently ice-laden (for review see Clarke [5] and Eastman [6]).
Thus, the objective of my communication is to present a comprehensive
data set on several biochemical adaptations of notothenioids to life in
high-Antarctic waters with special regard to fully pelagic Pleuragramma
antarcticum [7], benthopelagic Trematomus eulepidotus [8] and to the
seasonality of some of the biochemical processes.
G. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag ltalia 1998