Meeting Abstract
For broadcast spawning organisms like echinoderms, the timing of gamete release is essential for successful fertilization. However, synchronous release of gametes does not always occur. Delayed fertilization due to asynchronous gamete release or delayed contact between sperm and eggs could potentially have a large impact on the successful development of broadcast spawning organisms, but few studies have tested the effects of egg age on development beyond fertilization. Prior studies have focused on the presence of a fertilization envelope as a marker of successful development, however, the presence of a fertilization envelope alone does not necessarily indicate whether the fertilized zygote will develop into a normal larva and therefore may be a misleading indicator of successful development. We tested the effects of egg age on fertilization and early development in two species of asteroid echinoderms: Asterias forbesi and Acanthaster cf. solaris. We found that both species exhibited similar developmental responses to delayed fertilization. Fertilization was consistently high (90-100%) within 30 minutes of gamete release and/or egg maturation, but declined variably after that among different females. Importantly, we found that the frequency of normal development drops dramatically at each stage of development (blastula, gastrula, bipinnaria), with fewer than 30% of offspring developing to normal bipinnaria if fertilized more than an hour after gametes have been released. Our work suggests that researchers should carefully monitor gamete maturation and release in asteroid echinoderms, and likely other marine invertebrates, to avoid artifacts of gamete age on experiments with marine invertebrate eggs, embryos and larvae.
