PATTERNS OF GROWTH AND TRIACYLGLYCEROL CONTENT IN SNOW CRAB CHIONOECETES-OPILIO (BRACHYURA, MAJIDAE) ZOEAL STAGES REARED IN THE LABORATORY

Snow crab Chionoecstes opilio zoea I and zoea II larvae, hatched from females in a controlled mating experiment, were reared in the laborato ry at 10.1 degrees C and 28.0 parts per thousand salinity, to resolve the patterns of growth (dry weight [DW]) and change in energy reserves (triacylglycerols [TAG]) within a given moult cycle. The patterns of growth and change in TAG reserves were similar in each zoeal stage. Fo llowing hatching or a moult, the zoeae entered a phase of rapid size i ncrease, i.e. high daily growth rates (5.5 to 12.8% DW d(-1)), for 1/3 to 2/5 of the duration of the moult cycle. During the same period, th e zoeae accumulated TAG reserves until a maximum (TAG DW-1) was reache d at the end of the phase of rapid growth. The period of high growth r ates and of TAG accumulation is interpreted as the required time for t he zoeae to reach a point in development [i.e. point of reserves satur ation (PRS); Anger and Dawirs (1981)] where sufficient growth and ener gy reserves allow moulting to the next stage. Following the phase of r apid growth and TAG accumulation, the zoeae entered a phase of low dai ly growth rates (0 to 1% DW d(-1)) during which the TAG reserves decre ased to a minimum at the end of the phase. Prior to, and during the mo ult to zoea II, a phase of negative growth was observed in the zoea I larvae. We conclude that measurement of zoeal size and TAG content, al ong with morphometric criteria (e.g. epidermal retraction), can be use d to assess growth and nutritional condition of C. opilio zoeal stages from the sea.