Effect of temperature on the growth, survival, development and foraging behaviour of Sardina pilchardus larvae

Abstract

The effect of water temperature on the growth, survival, development and foragin behaviour of European sardine Sardina pilchardus larvae was examined in the laboratory. First the capability of early sardine larvae to cope with starvation was assessed at temperatures from 1 to 22 C. Second, we examined under ad libitum feeding conditions and across the range of temperature experienced by sardines during spawning along the Atlanto-Iberian coast (13-17 C) th ontogenetic changes in growth, survival and foraging behaviour of sardine larvae. Unfed larva had similar maximum survival times (11-12 d post hatching, dph) from 13 to 15 C, but the surviva time was significantly shorter at the coldest and warmest temperatures tested. The survival o exogenously feeding larvae increased with temperature, but younger endogenously feeding larva had higher survival at colder temperatures. The cumulative mortality after 25 dph, however was similar at the 3 temperatures. Not only larval growth rate increased with increasing temperature but ontogenetic development also occurred sooner and at smaller sizes. Notochord flexion which is a developmental milestone for fish, occurred 10 d earlier at 17 rather than at 13�C. Th time spent swimming and the foraging behaviour (orientations to prey, feeding strikes and successfu capture) significantly increased throughout the ontogeny and with temperature. This stud highlights how even modest changes in spawning temperature can lead to large changes in th survival and growth of larval sardine. This study also reveals some of the mechanisms whereb inter-Annual and seasonal variability in temperature can have significant ecological impacts at th population level.