Meeting Abstract

P3.16  Jan. 6  Delay of metamorphosis and its ecological consequences for solitary ascidians DICKERSON, B.H.*; STRATHMANN, R.R.; JACOBS, M.W.; Swarthmore College; Univ. of Washington; Univ. of Washington

For many marine invertebrate larvae, the settlement period is a key developmental transition from the larval to the adult body plans and an equally important ecological transition from planktonic to benthic life. Before the larvae are able to metamorphose, they must become competent to do so, normally by some physiological trigger enabling to change from tadpole to settled juvenile. Some marine invertebrate larvae can delay metamorphosis if the conditions are not yet favorable, but go through the process normally once in a suitable environment. In this study, we measured the consequences of delay of metamorphosis for survival, morphology, and growth of the stolidobranch species Boltenia villosa and the phlebobranch species Corella inflata. We also measured the competency period for both species and the effect of delay on the competent period for B. villosa. Delay of metamorphosis significantly decreased survival for C. inflata, while we found no significant effect was found for B. villosa. In the competency test, I found that most juveniles had settled after 72-96 hours of exposure to a settlement plate, with no new metamorphosis after 120 hours. Some of the B. villosa tadpoles that experienced a delay of metamorphosis showed development of ampullae and ballooning of the tunic.