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OSMOREGULATORY FAILURE AND DEATH OF FIRST YEAR LARGEMOUTH BASS EXPOSED TO LOW PH AND ELEVATED ALUMINUM, AT LOW TEMPERATURES IN SOFT WATER
Citation:
McCormick, J. AND K. Jensen. OSMOREGULATORY FAILURE AND DEATH OF FIRST YEAR LARGEMOUTH BASS EXPOSED TO LOW PH AND ELEVATED ALUMINUM, AT LOW TEMPERATURES IN SOFT WATER. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-92/268 (NTIS PB92205236), 1992.
Description:
Young-of-the-year largemouth bass (Micropterus salmoides) were exposed to pH levels from 8.0 to 4.5 in two water types, 1.5 and 13.4 mg Ca/L. Exposures were conducted at 3.8 degrees C for 113 d, followed by 14 d of increasing temperature to 18 degrees C. Two treatments in tbe softer water, one each at pH 5.0 and 4.5, bad A1 added to attain 3Oug A1/L; all other treatments were at approximately 5 ug A1/L. Tbe condition factor of fish in all treatment groups declined with exposure time at 3.8 degrees C. Fish in the 13.4 mg Ca/L water maintained osmotic homeostasis through pH 5.0. In tbe 1.5 mg Ca/L water, osmotic homeostasis was lost at pH 4.5 and at pH 5.0 when A1 was added. Mortalities were most prevalent when exposed in the 1.5 mg Ca/L water with added A1. Tbe probability of survival was directly correlated with blood osmolality; no correlation was found between survival probability and condition factor. A rise in blood osmolality occurred among fish from most exposure groups when the temperature was increased to 18 degrees C. When fish from these chronic treatments were challenged at pH 3.8, they had shorter survival times in the softer water and after longer preexposures.