Cold Adaptation and Stenothermy in Antarctic
Notothenioid Fishes: What Has Been Gained
and What Has Been Lost?
George N. Somero', Peter A. Fields', Gretchen E. Hofmann 2 , Randi B.
Weinstein 3 , and Helena Kawa1l 4
'Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
2Departrnent of Biology, University of New Mexico, Albuquerque, NM 87131,
USA
3Departrnent of Biochemistry, University of Arizona Health Sciences Center,
Tucson, AZ 85724, USA
4Departrnent of Marine Science, University of South Florida, St. Petersburg, FL
33701, USA
Introduction
Antarctic notothenioid fishes inhabit the coldest and most thermally stable
waters in the ocean. During their evolutionary histories, these fishes have
adapted to the threats posed by'potentially freezing temperatures as well as
the decelerating effects of reduced temperatures on rates of physiological
processes. Cold adaptation of numerous biochemical systems has been a
major feature of the evolutionary development of these species [1-4].
The extremely stable temperatures found in the Antarctic Ocean also
appear to have influenced profoundly the characteristics of these fishes, by
allowing the development of an extraordinary degree of stenothermy. A
study of the thermal tolerance limits of several species of nototheniid
fishes from McMurdo Sound, where temperatures are virtually constant
both seasonally and with depth, found that heat death occurs at only a few
degrees above 0 °C [5]. Long-term acclimation of McMurdo Sound
nototheniids is possible only at temperatures below 5°C. Thus, these
fishes have the narrowest range of thermal tolerance of any animal species
yet studied.
The acquisition of cold-adapted biochemical systems enables Antarctic
notothenioids to perform physiological tasks, such as mitochondrial A TP
synthesis [6], muscle contraction [7], and neural transmission [3], at
temperatures at which less cold-adapted ectotherms would cease to
metabolize. The gain of these remarkable capacities for function at nearG. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag Italia 1998
Notothenioid Fishes: What Has Been Gained
and What Has Been Lost?
George N. Somero', Peter A. Fields', Gretchen E. Hofmann 2 , Randi B.
Weinstein 3 , and Helena Kawa1l 4
'Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
2Departrnent of Biology, University of New Mexico, Albuquerque, NM 87131,
USA
3Departrnent of Biochemistry, University of Arizona Health Sciences Center,
Tucson, AZ 85724, USA
4Departrnent of Marine Science, University of South Florida, St. Petersburg, FL
33701, USA
Introduction
Antarctic notothenioid fishes inhabit the coldest and most thermally stable
waters in the ocean. During their evolutionary histories, these fishes have
adapted to the threats posed by'potentially freezing temperatures as well as
the decelerating effects of reduced temperatures on rates of physiological
processes. Cold adaptation of numerous biochemical systems has been a
major feature of the evolutionary development of these species [1-4].
The extremely stable temperatures found in the Antarctic Ocean also
appear to have influenced profoundly the characteristics of these fishes, by
allowing the development of an extraordinary degree of stenothermy. A
study of the thermal tolerance limits of several species of nototheniid
fishes from McMurdo Sound, where temperatures are virtually constant
both seasonally and with depth, found that heat death occurs at only a few
degrees above 0 °C [5]. Long-term acclimation of McMurdo Sound
nototheniids is possible only at temperatures below 5°C. Thus, these
fishes have the narrowest range of thermal tolerance of any animal species
yet studied.
The acquisition of cold-adapted biochemical systems enables Antarctic
notothenioids to perform physiological tasks, such as mitochondrial A TP
synthesis [6], muscle contraction [7], and neural transmission [3], at
temperatures at which less cold-adapted ectotherms would cease to
metabolize. The gain of these remarkable capacities for function at nearG. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag Italia 1998