MEPS 410:71-87 (2010)  -  DOI: https://doi.org/10.3354/meps08637

ABSTRACT: Adaptations and life history strategies have rarely been studied in deep-sea corals. Here we present laboratory data on the timing of larval release, reproductive output, substratum selectivity and growth of 2 alcyonaceans (Cnidaria, Octocorallia) from the bathyal zone of eastern Canada. Planulation patterns in 2 Drifa species were significantly influenced by seasonal productivity and the lunar cycle, and larval output was greater in larger colonies (from shallower depths). After release, planulae of Drifa sp. shifted their buoyancy to move between the bottom and the water column, whereas planulae of D. glomerata were largely demersal and crawled on the substratum until settlement (typically occurring after 1 to 30 d in both species). Settlement trials showed that planulae settled more readily on rough natural surfaces covered with biofilm than all other substrata tested and that larvae of colonies from deeper habitats were less selective than those originating from shallower habitats. In both species, the 8 primary mesenteries (and tentacle buds) appeared within 24 h post settlement, and polyps reached a maximum size after 2 to 3 mo. The first branching polyp was observed after ca. 9 mo of growth in D. glomerata, whereas no direct evidence of branching was detected in Drifa sp. over 21 mo of observation, although 2- and 4-polyp colonies were later discovered in the holding tank with adults. Together, these findings highlight dual traits of resilience (i.e. extended breeding period, long-lived larvae) and vulnerability (i.e. substratum selectivity, slow growth) in deep-sea corals.

KEY WORDS: Deep-sea · Corals · Reproduction · Brooding · Settlement · Growth · Drifa