D. Rissik et Im. Suthers, Enhanced feeding by pelagic juvenile myctophid fishes within a region of island-induced flow disturbance in the Coral Sea, MAR ECOL-PR, 203, 2000, pp. 263-273
The feeding success of post larvae and juveniles of 2 myctophid fishes (Dia
phus kapalae and Myctophum sp.) was compared between the free stream and a
flow-disturbed region in the lee of Cato Reef in the south Coral Sea using
particle-size analysis. Both taxa fed more successfully in the disturbed re
gion than in the free stream, where uplifting resulted in up to 50 % greate
r concentrations of small (250 to 1000 mu m equivalent spherical diameter)
prey items at depths between 30 and 70 m around the thermocline. Gut fullne
ss in both taxa was significantly related to the concentrations of small-si
zed zooplankton (D. kapalae: r = 0.63, p < 0.05; Myctophum sp.: r = 0.55, p
< 0.05). There were, however, differences in the sizes of food items consu
med in the free stream and the disturbed region and between the 2 taxa of f
ishes studied. Non parametric multi-dimensional scaling analysis indicated
that similar-sized individuals of D, kapalae and Myctophum sp. within a reg
ion consumed a different particle-size community, probably enabling them to
co-exist. The taxonomic composition of the diets of the 2 taxa reflected t
he available prey items around the island. In an oligotrophic environment s
uch as the south Coral Sea, island-induced disturbance appeared to be an im
portant contributor to the pelagic food web.