The influence of habitat on post-settlement processes, larval production and recruitment in a common coral reef sponge

Abstract

Population dynamics in marine sessile invertebrate communities are linked to both pre- and post-settlement processes. For species possessing low-dispersing, non feeding larvae, population demographics and distributions are primarily regulated by larval production and post-settlement effects. This study assessed the effect of temperature, photoperiod, rainfall and habitat on post-settlement mortality, growth, asexual reproduction (fission), larval production and recruitment in the abundant Great Barrier Reef brooding sponge Carteriospongia foliascens. The study was conducted over 24months at two locations characterized by distinct hydrodynamics (wave height). Location-specific differences in growth, body size and fecundity for C. foliascens were attributed to water movement, with a higher wave height range corresponding to higher abundance of larger, more reproductive individuals. The positive effects of hydrodynamics on growth and larval production also translated to higher recruitment levels highlighting a stock-recruitment relationship in this species. C. foliascens showed no evidence of fission, and exhibited fluctuating growth trajectories in all size classes investigated. Decreasing growth variability corresponded with increasing size, reflecting growth trajectories for species having indeterminate growth. Results presented in this study highlight the importance of habitat characteristics for post-settlement processes, larval production and recruitment in low dispersing sessile invertebrate species, such as brooding sponges.