Seasonal, reproductive, and nutritional influences on muscle "buffering capacity" in yellow perch (Perca flavescens)

"Effective non-bicarbonate" buffering capacity (or buffer value) was measured in white muscle of yellow perch (Perca flavescens) by titrations with mineral acid and base in a carbon-dioxide free, closed system. Yellow perch were collected at three month intervals throughout 1983 from an acidic lake (pH ∼ 4.6) and two alkaline lakes (pH ∼ 7.8) in northern Wisconsin. "Buffering capacity" was also determined for white muscle of perch kept in the laboratory under different regimes of temperature and ration. The mean "buffering capacity" of white muscle from yellow perch taken directly from natural environments ranged from 40.7 ± 3.1 (SD) slykes in March of 1983 to 53.7 ± 2.8 (SD) slykes in July of that year. These changes in "buffering capacity" were strongly correlated with water temperature. Egg production and thirty-day laboratory starvation produced significant decreases in "buffering capacity" and increases in the water content of yellow perch muscle. Fed perch in the laboratory had a temperature dependent "buffering capacity" similar to "field caught" fish. "Buffering capacity" of white muscle did not differ between yellow perch from acidic and alkaline lakes. Investigators using "buffering capacity" as a gauge of species differences in metabolic potential, should be wary of seasonal and reproductive factors that might alter their conclusions.