| The effects of water acidification on the composition of the adenine nucleotide pool and locomotor behavior of the estuarine teleost Fundulus grandis were investigated. Fish exposed for up to 96 hours to reduced pH exhibited highly significant declines in ATP concentration, total adenylate concentration, and adenylate energy charge, i.e.,;(ATP) + 1/2(ADP)(' ).;(AMP) + (ADP) + (ATP)(, ).;in brain, liver, and gill tissues. Muscle energy charge and ATP also decreased concurrent with increased ADP concentration, and particularly AMP concentration. Therefore, the total adenylate concentration was only slightly reduced. Exposure to pH 4.0 and 5.0 media produced the greatest declines in these parameters. Less pronounced declines were observed in fish exposed to pH 6.5 water. The greatest changes occurred within the first 24 to 48 hours of acidification but statistical analysis indicated that the hydrogen ion concentration was more important in altering adenylate metabolism than the length of exposure.;Low pH water induced changes in the daily locomotor activity pattern of F. grandis, particularly at pH 5.0 and 4.0. Box-Jenkins time series analysis was applied to the behavioral bioassay, permitting quantitative assessment of activity rhythm changes resulting from exposure to acidity. Activity data were obtained using an infrared photoelectric detection system. Results of time series model identification and estimation programs indicated a progressive decline in the daily rhythmicity of locomotor activity as the degree of acidification increased. Fish generally displayed hyperactive responses to low pH water with increased activity during the normally inactive diurnal periods. Under these conditions, extensive mucification, altered body coloration, difficulties in orientation and buoyancy control, and a cessation of feeding also occurred. The results of these studies suggest that environmental pH levels below 6.5 may critically impair energy metabolism and behavioral functions of fishes. |
