The Use of Scuba to Study Early Life Histories of Marine Invertebrates

Scuba has permitted in situ research of the early life histories of subtidal marine invertebrates, limited only by the small size of early stages. Investigators have used scuba to observe, among other things, coral spawning, including the spectacular mass spawns on the Great Barrier Reef, which established that most corals are hermaphroditic broadcast spawners. Observations and experiments have been conducted to measure fertilization rates of freespawning species, such as octocorals, sea cucumbers, sea urchins, and sea stars. Experiments have measured relative male reproductive success and the gamete traits that influence it in sea urchins. Finally, in tunicates, which produce larvae large enough to be seen by the naked eye and shortlived enough to be followed on a single dive, scuba has allowed direct observation from release to settlement, thus helping to shed some light on this process, which otherwise can only be studied indirectly.