ABSTRACT BENTHIC-PELAGIC COUPLING: THE ROLE OF LARVAL SUPPLY ON BENTHIC COMMUNITY STRUCTURE OF ROCKY SHORES
Keywords:
Supply-side ecology, rocky shore, settlement substrate, larval transport, conservation.Abstract
The life cycle of most organisms living on rocky shores presents a larval planktonic phase and an adult benthonic phase. Once released, the larvae are sometimes taken to far away from the coast, and they must find ways to return to the coast in order to settle down on a suitable substrate. ‘Supply-side ecology' is the scientific study of the effects of the supply of larvae and propagules on communities' structures, and its principles have been also applied to the study of population dynamics during the last two decades. The present review deals with: 1) factors affecting the larval supply (with emphasis on onshore transport), 2) larval settlement behavior, 3) the relationship between larval supply and settlement. Moreover, in this review the methods employed in previous studies are critically
analyzed and the utility of supply-side ecology for designing conservation and management plans is debated. The return of the larvae to the coast heavily depends on their swimming speed and vertical distribution in the water column. Retention of larvae near the shore seems to be recurrent and should be more deeply surveyed. Many studies failed to fi nd strong correlations between larval supply, settlement and recruitment probably due to methodological issues. However, other factors concerning the physiological status of the larvae and their behavior while picking a settlement substrate that are important in the small scale may account for the lack of correlation. Few studies made use of multiple working hypotheses that would allow evaluating the relative relevance of different pre-settlement factors for the community structure in rocky shores. Most studies that actually measured larval supply, dispersal and settlement were done in temperate regions. Understanding of the mechanisms driving larval transport and how the different populations in the rocky shores interconnect will certainly prove fundamental for designing adequate conservation and management plans.
