Relationship of RNA/DNA ratio and temperature to growth in larvae of Atlantic cod Gadus morhua

摘要

The RNA, DNA, and protein content of larval cod Gadus morhua reared in the laboratory at 3 temperatures and 3 densities of prey was measured. The data were used to define a quantitative relationship between RNA/DNA ratio (R/D), water temperature (T), and protein-specific growth rate (SGR, % d~(-1)). The nucleic acid content of each larva was determined with both a 2-dye flow-injection fluorometric assay (FIA) and a 1-dye/1-enzyme fluorometric microplate assay (MFA) in order to calibrate each methodology. The resulting equations were: SGR = 3.65 R/D + 1.02 T - 13.05 for FIA, and SGR = 4.03 R/D + 0.88 T - 11.16 for MFA. Measured growth rates ranged from negative (-8% d~(-1)) to 20% d~(-1). Water temperature and larval R/D explained 37 to 39% of the variability in the observed growth rate. The models are applicable over temperatures ranging from 2.5 to 9.5℃ and can be used to determine short-term growth rates of cod larvae collected from both the laboratory and field.