Effects of temperature on development and survival of embryos and on larval production of Chorus giganteus (Lesson, 1829) (Gastropoda: Muricidae)

Chorus giganteus shows faster intracapsular embryonic development at high temperature but this is generally associated with a high embryonic mortality and low larval production. The present study was undertaken to determine the optimal combination of temperature and developmental stage for a successful (faster) larval production at high temperature. Embryos at three stages of intracapsular development (early stage [ES-embryos], late stage [LSembryos] and trochophore post nurse-egg ingestion stage [TPI embryos]) were acclimated at 12ºC then incubated at 12, 15 or 18ºC to evaluated larval production. The median hatch time was accelerated by increasing water temperature. However, the hatching success of ES- and LS-embryos was compromised by higher temperatures, decreasing from a 51 ± 2% at 12ºC to 8 ± 1% at 18ºC in ES-embryos and from 53 ± 2% at 12ºC to 20 ± 0.2% at 18ºC in LS-embryos. The incidence of developmental abnormality increased with temperature from 14 ± 2% at 12ºC to 46 ± 3% at 18ºC in ES-embryos and from 8 ± 1% at 12ºC to 28 ± 1% at 18ºC in LS-embryos. By contrast, hatching success of TPI embryos ranged from 65-70% and the incidence abnormality was only between 13 and 20%, with both factors being independent of temperature. Thus the probability of producing and releasing normal larvae was significantly affected by the combined effect of temperature and embryonic stage at the initiation of the culture. A reduced ability to ingest nurse eggs may account for the variation in larval production between the trials.