MEPS 368:9-22 (2008)  -  DOI: https://doi.org/10.3354/meps07625

ABSTRACT: Sea level rise can affect the biodiversity of coastal areas through alterations of features of the substratum, including the geometry of shorelines. Field measurements on the rocky shore of Calafuria (NW Mediterranean Sea) showed that a rise in sea level in the range of 5 to 50 cm would increase the availability of steep substrata (>40°) for assemblages of algae and invertebrates by up to 58% compared to current conditions. Comparisons between assemblages on horizontal and vertical substrata revealed clear differences in the composition and abundance of common taxa. Clearing experiments replicated on vertical and gently sloping surfaces at 2 heights on the shore were performed to test hypotheses about the role of recruitment and post-recruitment processes in maintaining differences between substrata. Comparisons of recolonizing assemblages with unmanipulated controls allowed us to test the hypothesis that a change in slope of the substratum affected the ability of assemblages to recover after a disturbance. Results indicated that differences in the structure of assemblages between vertical and horizontal substrata were maintained by a combination of recruitment and post-recruitment processes, although the relative importance of these processes differed among taxa. Nonetheless, patterns of recovery of assemblages were comparable between the 2 substrata. These findings suggested that sea level rise, by increasing the proportion of vertical substrata at the expense of horizontal surfaces, will lead to the expansion of assemblages dominated by encrusting coralline algae and grazing gastropods, and the reduction of abundance of filamentous forms and barnacles. The resilience of assemblages, however, appeared unaffected by the aspect of the substratum.

KEY WORDS: Sea level rise · Habitat structure · Resilience · Rocky shores · Recruitment · Mediterranean Sea