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Here is the info ;
Although it has been hypothesized that temperature is closely linked to membrane composition, relatively few studies have been conducted to determine if a correlation exists between lipid composition and cold tolerance. This study was designed to determine the effect of a sudden temperature change (a simulated cold front) …
Fish deaths due to cold temperatures have frequently been reported. It is generally believed that deaths arise from the rapidity of dropping temperatures whereby the fish are unable to acclimate to the lower temperature despite being within their biokinetic range. In these fish, the fat apparently hardens in the colder water, causing the fat-impregnated muscles to stiffen and the fish to become exhausted and lose movement. The rate of increase in the ability of fish to tolerate higher temperatures usually requires less than 24 h at temperatures above 20C, whereas the gain in resistance to lower temperatures is a much slower process, requiring up to 20 d in some species (Doudoroff 1942; Brett 1944). The rate of resistance to lower temperatures is governed in part by the rate of metabolism, which is depressed at lower environmental temperatures. The simulated cold front in this study resulted in higher mortalities
The rapid onset of cold temperatures has been reported as the cause of death in several species of fish (Verril 1901; Storey 1937; Galloway 1941; Gunther 1941; Ash et al. 1974; Coutant 1977; Mitchell 1990). It is believed that the lipid composition in the fish muscle plays a vital role in the ability of fish to adapt from one temperature to another (Hazel 1984; Greene and Selivonchick 1987; Henderson and Tocher 1987). Phospholipids are the class of lipids in which the most obvious changes occur.
the ability of a fish to alter its lipid composition when placed in colder water is one factor that determines survival.
This study was designed … determine the effect of a sudden temperature change (a simulated cold front) on striped bass, white bass, and their hybrids fed either a natural or prepared diet, as well as to determine their lower incipient lethal temperature. The association of fatty acid composition and unsaturated: saturated fatty acid ratios in these fish were examined with respect to their tolerance to cold.
The dynamics of lipid composition of cells occurs in order to maintain a constant fluid matrix for enzymes associated with membranes (Greene and Selivonchick 1990). Different species of fish differ in their patterns of fat deposition and mobilization, which in turn affects the temperature range in which the species can grow and survive. For example, the Nile tilapia Oreochromis niloticus does not store excess lipids in the musculature but rather relies on visceral deposits that it is incapable of mobilizing at low temperatures, which results in high mortalities between 8C and 6.5C (Satoh et al. 1984).
Last edited by ewest; 11/30/13 08:44 PM.
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