SREL Reprint #0465

 

 

 

Body Condition and Stomach Contents of Fish Inhabiting Thermally Altered Areas

R. E. Lattimore and J. W. Gibbons

 

Abstract

Body condition and stomach contents in three species of sunfish (Centrarchidae) were compared in natural and thermally influenced streams in South Carolina.  The thermal stream was divided for sampling purposes into four zones variously affected by the heated water.  Individuals of each species collected from the normal temperature adjacent to the heated water had higher condition factors than those from any other area.  Also, the largest individuals collected in the thermal stream were from the area of high temperatures.  Large body size may allow tolerance to sudden changes in water temperature.  Although higher percentages of the fish from the natural stream had food in their stomachs, their diet was more herbivorous than that of thermal stream.

With the increased usage of power reactors in the United States, studies of thermal loading and its effect on aquatic organisms have become very important.  Although many studies have been conducted in lake or river environments (Gibbons and Sharitz, 1974a,b), few, if any, studies have examined the biological changes associated with stream ecosystems which intersect with reactor effluents having temperatures lethal for most aquatic organisms.  These systems provide a unique opportunity to examine plant or animal populations which are confronted with a spectrum of thermal conditions ranging from natural to abnormally hot.

Respiration rate in aquatic animals increases as water temperatures are elevated, so that a high metabolic rate could result in poor body condition if food is limiting.   Bennett and Gibbons (1972) found that bass near the “hot dam” of Par Pond, a reservoir receiving thermal effluent, contained less food in their stomachs then those at the “cold dam”.  They conducted that this may reflect an increase in the rate of digestion at high temperatures.  Graham (1974) reported that the fish from the cool end of Lake Julian, N.C., showed considerable difference in external physical conditions from emaciated sunfish taken from a cove receiving thermal effluent.  Zhiteneva (1971) found that young bream inhabiting the warm water zone of Konskova power station in Russia where characterized by a lower relative body depth than those from other areas of the same reservoir.  These and other studies suggest that water temperature may serve as a controlling factor by affecting metabolic rates and consequently influencing the body condition of fish.

The objective of this study was to compare differences in body condition and stomach contents of fish in stream areas which are variously affected by heated effluent.  Three species of sunfish (Centrarchidae) were used in this study:  spotted sunfish (Lepomis punctatus), redbreast sunfish (L. auritus) and blue-spotted sunfish (Enneacanthus gloriosus).

 

SREL Reprint #0465

Lattimore, R.E. and J.W. Gibbons. 1976. Body condition and stomach contents of fish inhabiting thermally altered areas. The American Midland Naturalist 95:215-219.

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