Summary
Young-of-the-year largemouth bass, Micropterus salmoides, were exposed to four concentrations of sulphuric acid (pH levels 7.2, 6.1, 4.8, and 3.7) for 30 days, and the frequencies of feeding acts and activity bouts, and time budgets were recorded. Juveniles at pH 6.1 and at pH 4.8 performed the two feeding acts, bites and orientations, more often, and spent more time feeding than bass at pH 7.2. Bass at pH 3.7, however, reduced feeding, and spent a significantly larger portion of their time hovering in the water column. Frequencies of comfort and agonistic acts increased with a decline in pH. Alterations of behavioural repertoires of young-of-the-year largemouth bass were useful indicators of sulphuric acid exposure.
Methodology
Young-of-the-year largemouth bass were seinenetted from July 12 to July 19, 1982 from Lake Opinicon, 30 km northeast of Kingston, Ontario. There were twenty-five bass in each exposure tank. Initial mean total length of all bass was 41.9 ± 0.3 mm (n = 200). There was no significant difference in initial total length of bass among tanks (analysis of variance, p<0.05). Fish were acclimated to pH 7.2 for two days, then transferred to the next lower test pH level for two days, and so forth, until the desired test pH level was reached. Exposure began July 27,1982.