ASFB Home > The effects of spatial and temporal factors on the abundance of seven key finfish species along south-western Australia.

The Effect of Temperature on the Swimming Ability in Tropical Reef Fish Larvae

Bridget Green and Rebecca Fisher

James Cook University, DOUGLAS, AUSTRALIA

THEME: ASFB

Amphiprion melanopus larvae were maintained at two rearing temperatures (25oC and 28oC) and their critical swimming ability was measured at two swimming temperatures (25oC and 28oC). Larvae from both rearing temperatures were swum at 7days after hatching (dah), coinciding with one day prior to metamorphosis for 28oC, and at 11 dah for fish reared at 25oC, coinciding with one day prior to metamorphosis for this treatment. This combination of age and temperature tested for the effects of rearing temperature as well as swimming temperature on the swimming ability in relation to absolute- and developmental- age. Seven day old larvae reared at 28oC had significantly faster absolute swimming speeds than larvae of the same age reared at 25oC, but were not significantly faster than larvae 11 dah reared at 25oC. However, when swimming ability was analysed in relative terms (bls-1) rather than absolute terms (cms1), larvae 11dah reared at 25oC were significantly slower than larvae 7dah reared at 28oC. Swimming temperate did not affect swimming performance for fish from either of the rearing temperatures. Larvae raised at 25oC were significantly larger at 11dah than all other larvae. These results do not agree with the current theory on survival in marine fish larvae that 'bigger is better'. In this instance larvae that were bigger but came from colder water did not perform better than their siblings raised at 28oC. Decreased swimming ability reduces the ability of larvae to escape