Abstract

Larval behavior in the water column and preference among natural benthic habitats are known to determine initial spatial distribution patterns in several sessile marine invertebrates. Such larval attributes can be adaptive, promoting adult benthic distributions which maximize their fitness. Further benthic processes may, however, substantially change initial distribution of settlers. In this study, we first characterized spatial distributions of adult colonies and single-polyp recruits of the invasive azooxanthellate coral Tubastraea coccinea over substrates of different orientation, and evaluated their consistency at both small (several tens of meters) and intermediate (a few km) spatial scales. We then assessed, through field and laboratory experiments, larval preferences and relative settlement and recruitment rates on surfaces with different orientations to determine whether processes taking place during the larval and early post-larval stages could help explain the distribution patterns of recruits and adult colonies. Results suggest that larval passive buoyancy and active larval behavior, unrelated to light conditions, determine a clear settlement distribution pattern, in which the density of settlers is highest at undersurfaces and almost nil at upward facing horizontal substrates. Except for an almost absence of settlers, recruits and adult individuals on upward facing horizontal habitat, there is substantial mismatch between the distribution of settlers and that of recruits and adult colonies. The latter were also common in vertical substrate in the field. We speculate that coastal runoff at the study area and subsequent sedimentation may inhibit coral development on flat upward facing habitat, and that competitive interference and pre-emptive interactions with other azooxanthellate corals could constrain abundance of T. coccinea in underface horizontal habitat. (C) 2013 Elsevier B.V. All rights reserved.