Energetic cost of sustained swimming in the late pelagic stages of reef fishes

Abstract

The late pelaglc stages of reef f ~s h e s are capable of swimming substant~al distances w h ~c h may sign~flcantly mod~fy their dispersal The energetic cost of this swlmming, at 13 5 cm S-', was measured for the late pelagic stages (mean total length ranging from 10.8 to 22.4 mm) of 9 specles from 4 reef fish familles (Pomacentridae, Pomacanthldae, Chaetodontldae and Lethnnidae] Of the potentlal sources of energy (lipld, carbohydrate and protein), all were utilised, but lipid appeared to be the most energetically important across the specles. Llp~d levels decreased s~gniflcantly In 5 of the 9 specles. The decrease and the relatlve percentage of energy lost In the form of h p ~d was greater than for carbohydl-ate and proteln The pattern of enel-gy utilisation v a r ~e d among specles. The greatest decrease in energy stores was seen In the heaviest species, i v h ~c h swam for the longest d u r a t ~o n (the chactodontids and I(>thrin~d), showlng up to 72'LL8 decrease in 11p1d. 66% decrease* in carbohydrate and 39% decrease in proti'ln The lighter specles, which swam for shorter time perlods (the pomacentrids and the pomacanth~d), showed cornparatlvely 11ttle change In energy reserves after s w ~m m i n g . lnltial levels of energy reserves correlated \vith d ~s t a n c e surllm and were greatest In the heavier specles