Spawning and development of three coral-associated Lithophaga species in the Red Sea

Abstract

Lithophaga date mussels from three species (L. lessepsiana, L. simplex and L. purpurea) were removed from their stony coral hosts in the Red Sea at Eilat, Israel. Spawning, observed in the laboratory on several occa- sions during 1987-1988, appeared to be closely tied to lunar periods, occurring primarily during the last quarter and the new moon. Embryonic and larval development was typical of that described for other mytilids and, ex- cept for pigmentation differences, which could be dis- cerned during embryogenesis, the developmental stages of the three species were indistinguishable. Development to the pediveliger stage took 3 to 4 wk in standard culture conditions, but raising the temperature to 27.5~ in- creased the growth rate of larvae of L. lessepsiana by as much as three-fold, so that the pediveliger stage was at- tained in 16 d. Larvae resulting from spawning by L. simplex adults removed from the coral Astreopora myrio- phthalma grew significantly faster in culture than larvae from adults removed from the coral Goniastrea pectinata (comparison of slopes, p < 0.05). The latter individuals showed a 6-d growth plateau at the early umbone stage. Metamorphically competent larvae were capable of de- laying metamorphosis for up to 4mo, which would allow an extended period for dispersion and would increase the chance of finding a suitable substratum in the natural environment.