OXYGEN CONSUMPTION AND AMMONIA EXCRETION OF LARVAE AND JUVENILES OF THE BAY SCALLOP, ARGOPECTEN IRRADIANS CONCENTRICUS (SAY)

Y.T. Lu, N.J. Blake, J.J. Torres, 1999

Journal of Shellfish Research, 18 (2): 419-423 (from Current Contents)

Abstract :

Rates of oxygen consumption and ammonia excretion were determined at 25 C for larval and juvenile bay scallops Argopecten irradians concentricus. Oxygen consumption rate (Vo(2), mu lO(2) h(-1)) varied with body size ash-free dry weight (AFDW, mg) according to the relation Vo(2) = 7.199 AFDW(0.921) for larvae and Vo(2) = 2.142 AFDW(0.905) for juveniles. Mean weight-specific Vo(2) ranged from 14.66 to 15.84 mu lO(2) mg AFDW(-1) h(-1) for larvae and from 1.80 to 5.28 mu lO(2) mg AFDW(-1) h(-1) for juveniles. Weight specific Vo(2) declined with increasing body size at > 2 mm shell height but became independent of body size at > 2 mm shell height. Swimming was estimated to cause 8 to 29% of the total larval oxygen demand. In juveniles of 3.5 to 5.0 mm shell height, Vo(2) increased as temperature increased from 15 to 30 C, being 1.24 +/- 0.35, 1.77 +/- 0.70, 2.33 +/- 0.85., and 2.74 +/- 0.57 mu lO(2), mg AFDW(-1) h(-1) at 15, 20, 25 and 30 C, respectively. The Q(10) was 2.99 at 15 to 20 C, 1.74 at 20 to 25 C and 1.37 at 25 to 30 C. Ammonia excretion rate (U, mu gNH(4)-N h(-1)) increased with body size following the equation U = 0.161 AFDW(0.928). Energy loss through ammonia excretion was equal to 1.5 to 3.7% and 13.5 +/- 2.8% of the respiratory energy loss in larvae and juveniles, respectively.

(Univ S Florida, Dept Marine Sci, 140 7th Ave S, St Petersburg, FL 33701, USA)

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