Field and laboratory determinations of hypoxic effects on RNA-DNA ratios of bluegill

We used RNA-DNA ratios in both field and laboratory experiments to examine the effects of hypoxia on short-term growth of bluegill Lepomis macrochirus collected from the lower Atchafalaya River Basin, Louisiana. In the field experiment, RNA-DNA ratios of bluegill (17.8-52.3 g) from hypoxic habitats (DO < 2.0 mg L-1; n = 26) were significantly lower than ratios of bluegill from normoxic habitats (DO > 4.0 mg L-1; n = 31). In each of two laboratory experiments 40 bluegill (14.54-76.70 g) were individually placed in aquari a to test the effects of hypoxia on RNA-DNA ratios. Additionally, bluegill were fed at different rates in the first experiment to determine the effect s of feeding level on RNA-DNA ratios. Results of the first experiment confi rmed the sensitivity of RNA-DNA ratios to short-term changes in growth, as fed bluegill had significantly higher ratios than starved bluegill. In both experiments RNA-DNA ratios were not significantly different in bluegill su bjected to hypoxia. Results of the study indicate that laboratory experimen ts did not adequately simulate increased bioenergetic demands and fluctuati ng DO levels found in hypoxic areas of the Basin.