Physiology and ecology of notothenioid fishes of the Ross Sea

Abstract

Pereiform fishes of the suborder Notothenioidei are the dominant fishes in the Ross Sea and in the Southern Ocean in general. They have evolved physiological adaptations which ensure their survival in ice-laden seawater at a temperature of -1.go C and extended their habitat range. Among these adaptations are relatively high metabolic rates made possible by enzymes efficient in catalyzing energyproducing reactions at subzero temperatures; a restricted range of temperature tolerance; slow growth rates in spite of relatively high metabolic rates; antifreeze glycoproteins which reduce the freezing point of body fluids below that of seawater and prevent ice crystal growth; aglomerular nephrons which preclude the loss of small molecular weight antifreeze molecules in the urine and mechanisms (especially skeletal reduction and lipid deposition) promoting neutral buoyancy in some species even though swim bladders are absent. Species with different buoyancies are associated with the pelagic, cryopelagic, benthopelagic and benthic habitats in the Ross Sea. Physiological specializations, including buoyancy adaptations in many body systems, and the absence of competition from other fishes allowed this presumably monophyletic group to radiate into several habitats in the Southern Ocean.

Temperature-dependent metabolism in Antarctic fish: Do habitat temperature conditions affect thermal tolerance ranges?

“…While this is supported by results from studies on enzyme levels (e.g. Crockett and Sidell 1990) and matches with observations of low growth in polar ectotherms (DeVries and Eastman 1981;La Mesa and Vacchi 2001;Pörtner et al 2005), results of wholeorganism metabolic rates are controversial. Studies at lower organismic levels are often less complex and yield clearer results.…”

“…Antarctic fish exhibit different adaptations to their constantly cold environment, such as a lack of heat shock response, expression of anti-freeze glycoproteins, a lack of haemoglobin and myoglobin, higher mitochondrial densities as well as other compensatory adaptations of the heart and circulatory system (e.g. DeVries and Eastman 1981;Coppes Petricorena and Somero 2007). Compared to temperate species that experience broader environmental temperature fluctuations, Antarctic fish have very narrow temperature windows (Somero and DeVries 1967;Van Dijk et al 1999;Brodte et al 2006).…”

Antifreeze glycopeptides and peptides in Antarctic fish species from the Weddell Sea and the Lazarev Sea

“…Low temperatures have pervaded the Southern Ocean for some 40 mill~on yr (Kennett 1977). Recent data suggest more or less constantly low temperatures (+3"C to -2°C; Hellmer & Bersch 1985) since about 13 million yr ago (Eastman & Grande 1989), which have led to the high degree of stenothermy and endemism of the fish fauna (DeVries & Eastman 1981).…”

Myogenic cell cycle duration inHarpagiferspecies with sub-Antarctic and Antarctic distributions: evidence for cold compensation

“…Finally, annual growth rates of the Antarctic notothenioids are also generally believed to be slower than those of fish from temperate regions (DeVries and Eastman, 1981;Everson, 1984), although recent analyses of growth performance data have questioned this view (Kock, 1992;Kock and Everson, 1998). These new analyses suggest that only fish from the high-Antarctic zone, where water temperature is stable at -1.86°C, exhibit very slow growth rates, the growth performance of fish from lowerAntarctic latitudes/sub-Antarctic waters being similar to that of many temperate fish species (Kock and Everson, 1998;Morales-Nin et al, 2000;La Mesa and Vacchi, 2001).…”