ANNA-CLAIRE FERNANDEZ AND G. JOAN HOLT, The University of Texas at Austin, Marine Science Institute, 750 Channelview Drive, Port Aransas, Texas 78373, USA

Red drum larvae are subjected to a wide range of temperatures during transport from spawning to nursery areas. Cooler water temperatures can directly or indirectly reduce larval growth rate. We have observed that changes in larval growth, caused by diet, are reflected in RNA:DNA ratios. An experiment was designed to investigate whether temperature influenced changes in growth are reflected in RNA:DNA ratios. Eggs from captive red drum were hatched in 25.5°C degree seawater. Larvae were then transferred to 28°C or 23°C seawater. Standard lengths, nucleic acid concentrations (using the ethidium bromide fluorometeric technique) and soluble protein concentrations were measured every other day. Growth rates from the warm treatment were significantly greater than those found in the cooler treatment. Per standard length, RNA, DNA and RNA:DNA was not significantly different between fish acclimated to 28°C or 23°C. These same results were seen in red drum larvae grown at 27°C and 22°C. Though there were differential growth rates between treatments, the same amount of RNA and DNA is produced per millimeter of fish. Temperature influenced changes in growth only effect the rate of growth and not amount of RNA or DNA per size.