Publication Abstract

The influence of egg size andincubation temperature on the condition of Solea solea larvae at hatching andfirst feeding

S.M. Baynes and B.R. Howell

Sole (Solea solea (L.))eggs of different sizes, spawned by a captive broodstock were held at 9, 12 and 15°C.Development of the hatched larvae was monitored until the yolk reserves were exhausted.Yolk utilization and morphometric changes were monitored during the pre-feeding stages.Whole larva concentrations of nucleic acids (RNA and DNA) were measured to assess theirvalue as indicators of growth and nutritional condition. Larvae hatching from the largereggs had more yolk and were both longer and had deeper myotomes than those hatching fromthe smaller eggs. Further, more yolk remained at the time a functional jaw had developed,in larvae from the larger eggs compared with those from the smaller eggs. The temperaturesinvestigated affected growth rate after hatching but not the relative timing of changes ingrowth in length and myotome height of the larvae. These were similar when compared on atimescale based on the duration of embryo development at each temperature. At 9°C,however, the relative time of formation of an articulated jaw appeared to be delayedcompared with larvae developing from the same size eggs held at 12 or 15°C. There was noevidence of incipient starvation before the jaw was functional for larvae from either eggsize at these temperatures, although there was shortly afterwards, particularly in larvaefrom the small eggs. DNA concentration proved to be a more useful indicator of larvalnutritional condition than other nucleic acid ratios.

Reference:

S.M. Baynes and B.R. Howell, 1996. The influence of egg size and incubation temperature onthe condition of Solea solea larvae at hatching and first feeding. Journal of ExperimentalMarine Biology and Ecology, 199: 59-77