Prey selection by greenback
flounder Rhombosolea tapirina (Günther) larvae
G.W. Shaw, P.M. Pankhurst, G.J. Purser-2003
Aquaculture, 228(1-4): 249-265
Abstract:
The potential for greenback flounder (Rhombosolea
tapirina), as a new species for aquaculture in temperate Australia, is
currently under investigation. Isolation of an endemic temperate rotifer, Testudinella
sp., provided the opportunity to assess this genus against standard live
prey species used in aquaculture. Greenback flounder larvae were offered a
range of rotifer prey species (Testudinella sp., Brachionus
rotundiformis, Brachionus plicatilis) and the brine shrimp Artemia,
either in isolation or combination, in order to test the hypothesis that
factors besides prey size affect prey selection. From first-feeding to
approximately day 13 post-hatching, greenback flounder larvae preferentially
consumed the rotifer Testudinella sp. over the larger width rotifer B.
plicatilis and to a lesser extent the rotifer of similar width
dimension, B. rotundiformis. From day 15 post-hatching, consumption
(number of prey consumed per larva per unit time interval) and selection (α)
of B. plicatilis was significantly higher than of Testudinella
sp. and Artemia, but by day 18 post-hatching, there was a shift of
feeding preference to Artemia. This indicated that size of prey
ingested increased with age, likely reflecting an ontogenetic increase in
larval sensory function, mouth gape and prey capture and handling ability.
Significant selection of Testudinella sp. over the larger rotifer B.
plicatilis occurred despite greenback flounder larvae being able to
consume B. plicatilis. This along with significant selection (day 11
post-hatching) and consumption (days 11 and 12 post-hatching) of Testudinella
sp. over the rotifer of similar width B. rotundiformis, indicates
that prey size is not the sole determinant of prey consumption and suggests
that greenback flounder larvae exhibit both species-specific and
size-specific prey selection. Understanding the basis of prey selection by
larval fish predators is essential for enhancing prey consumption in
culture, especially in the context of ontogenetic shifts in prey species
preference.
(School of Aquaculture, Tasmanian Aquaculture and
Fisheries Institute, University of Tasmania, Locked Bag 1/370, Launceston
7250, Australia, e-mail: Gavin.Shaw@utas.edu.au)