The Role of Dissolved Organic Material in the Nutrition of Pelagic Larvae: Amino Acid Uptake by Bivalve Veligers

SYNOPSIS. Studies on the role of dissolved organic materialin the nutrition of marine invertebrates have largely been confinedto adults. However larval forms, with a higher surface areato volume ratio, have a greater weight specific capacity forabsorbing dissolved organic material than adults. Autoradiographic,biochemical, and kinetic experiments with bivalve larvae allindicate that amino acid uptake and translocation mechanismscan operate efficiently at naturally occurring substrate concentrations.The mechanisms operate throughout the life-span of the animal,from fertilized egg to adult. Experimental evidence is presentedto show that the kinetics of uptake by larvae allow them tocompete with bacteria for dissolved organic material in seawater. In larvae, supplementary sources of energy may be moreimportant than in adults since larvae are provided with minimalfood reserves by the parent and must pass through periods whenpaniculate feeding cannot occur.