Early Succession Patterns of Benthic Assemblages on Artificial Reefs in the Oligotrophic Eastern Mediterranean Basin

Abstract

The colonization of artificial structures by benthic organisms in the marine realm is known to be affected by the general trophic patterns of the biogeographical zone and the prevailing environmental traits at the local scale. The present work aims to present quantitative data on the early settlement progress of macrofaunal benthic assemblages developing on artificial reefs (ARs) deployed at the Underwater Biotechnological Park of Crete (UBPC) in the oligotrophic Eastern Mediterranean. Visual census and subsequent image analysis combined with scraped quadrats were used to describe the establishment of the communities and their development over three consecutive campaigns, spanning 5 years post-deployment. Macroalgae consistently dominated in terms of coverage, while sessile invertebrates displayed different patterns over the years. Polychaeta and Bryozoa were gradually replaced by Cnidaria, while Porifera and Mollusca displayed an increasing trend over the years. Motile benthos was mainly represented by Mollusca, while the abundance of Polychaeta increased in contrast to that of Crustacea. For both sessile and motile assemblages, significant differences were observed among the years. The results of this study indicate that ecological succession is still ongoing, and further improvement in the monitoring methodology can assist towards a more accurate assessment of the community composition in complex AR structures.

Habitat Fragmentation Enhances the Difference between Natural and Artificial Reefs in an Urban Marine Coastal Tract

“…Early studies on the colonization of artificial structures in the NW Mediterranean indicated that it takes approximately 3 years for the community to reach a mature stage in terms of both biomass [72] and species composition [73,74]. Similar experiences in other seas, however, have shown that climax communities were reached in 5 to 20 years [75][76][77], but the differences between natural and artificial reefs have been observed to persist even for much longer times [71,78,79]. At St. Eustatius (eastern Caribbean), no significant difference in the density of coral-associated fauna was found between a centuries-old manmade structure and the nearest natural reef [49], notwithstanding differences in relief rugosity and surface structure, which are also known to exert an important influence on the entire epibenthic community [52,80].…”