Importance of parental effects on larval survival in Sardina pilchardus

A combined field and laboratory study was carried out to determine the impo rtance of parental effects (spatial and temporal variations in spawning, eg g size and biochemical composition of the egg) on larval survival in Sardin a pilchardus, Egg abundance was positively correlated with the seston organ ic content (SOC; a combination of total protein, carbohydrate and lipid con tent) of the size particle fraction 20 to 1000 mum. This was interpreted as a reproductive strategy, to spawn more eggs in areas and during periods of enhanced food availability to larvae. Larval survival under starvation con ditions was related to temperature, but only when just the larvae in which the yolk-sac was fully absorbed at death were considered. However, if larva l survival time was estimated considering all larvae, including those which died before yolk-sac absorption, larval survival time was related to the b iochemical composition of the egg. Larval survival time increased as the pe rcentage of protein in the egg increased, indicating the importance of prot ein under food limiting conditions. Furthermore, percentage of larvae with yolk-sac completely absorbed at death was higher as egg protein percentage increased. Although producing eggs with a higher proportion of proteins in response to diminishing food availability could maximise larval success und er starvation conditions this parental strategy was not exhibited by S. pil chardus. There was not a significant relationship between egg protein perce ntage and SOC. Biochemical composition of the egg seemed to vary according to temperature of the water.