DRINKING RATE, UPTAKE OF BACTERIA AND MICROALGAE IN TURBOT LARVAE

K.I. Reitan, C.M. Natvik, O. Vadstein-1998

Journal of Fish Biology, 53 : 1145-1154

Abstract :

The drinking rate of turbot larvae increased from 14 to 120 nl/larva/h from day 2 to 11 after hatching, which gave a slightly increased specific drinking rate (calculated per biomass) from day 2 to 7 (0.8 -1.9 nl/microg carbon/h). The clearance rate of both algae and bacteria was 10-100 times higher than the drinking rate, which indicated that the larvae had an active uptake of both algae and bacteria. On day 2 and 4 after hatching highest clearance rate was observed for Tetraselmis sp. On day 2 and 4 after hatching highest clearance rate was observed for Tetraselmis sp. On day 6 about the same clearance rate was observed for bacteria, Isochrysis galbana and Tetraselmis sp. Until day 4 the turbot larvae had a higher ingestion rate of Tetraselmis sp. than of I. galbana, whereas on day 6 the rates were similar (28-41 ng carbon/larvae/h). The assimilation efficiency was somewhat higher for I. galbana than for Tetraselmis sp., and on day 6 the assimilated algae constituted 1.5 and 0.9% of the larval biomass of I. galbana and Tetraselmis sp., respectively.

(Norwegian University of Science and Technology, Brattora Research Centre, Department of Botany, N-7034 Trondheim, Norway)

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