Comparing sessile benthos on shallow artificial versus natural hard substrates in the Eastern Mediterranean Sea

Abstract

Artificial structures cover a considerable part of the Mediterranean coasts. In the Aegean Sea, most studies related to artificial structures have focused in vagile fauna on harbors and marinas but little attention has been given to the sessile biota on coastal defense structures. The aim of this work was to describe for the first time the shallow sublittoral sessile benthos on coastal defense structures in Crete (Eastern Mediterranean Sea) in order to identify potential differences in comparison to natural rocky substrates, adopting both a taxonomic and functional (i.e. macroalgal structural complexity) approach. Three shallow (1-3 m) localities were studied in the north coast and three in the south coast of the island (six localities in total). At each locality, two types of hard substrate were selected: an artificial coastal defense structure (rip-rap) and the nearest natural rocky substrates. The percent cover of sessile taxa was calculated using random points counts over photoquadrats (20 x 20 cm). The structure of the assemblage differed between artificial and natural habitats. Values of Shannon-Wiener’s diversity index and number of taxa were higher in natural substrates. In addition, cover of arborescent macroalgae was lower on artificial substrates. In conclusion, rip-raps do not function as surrogates of natural hard substrates in the study area since their shallow subtidal assemblages differ in terms of community structure, diversity and functionality. The deficient performance of such artificial structures could be attributed to the combined effects of abiotic factors and biotic processes, including substrate nature and roughness as well as differential grazing pressure.

Macroalgal vegetation on a north European artificial reef (Loch Linnhe, Scotland): biodiversity, community types and role of abiotic factors

“…On the other hand, Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10811-019-01918-2) contains supplementary material, which is available to authorized users. reckless use of ARs has also raised scientific concerns in regard to natural habitat destruction, contaminant release, foodweb alterations and invasive species propagation (Salomidi et al 2012(Salomidi et al , 2013Sedano et al 2019).…”

Comparison of Recruitment Patterns of Sessile Marine Invertebrates According to Substrate Characteristics

“…Species identification was performed in the field. Regarding species with small individuals or taxa that were difficult to identify, the encyclopedia and various literature were referenced [53][54][55][56][57][58][59] based on photographic data. Each taxon was analyzed by grouping it at the phylum or class level for statistical analysis.…”

“…In particular, a study comparing natural and artificial substrates was conducted, and Cacabelos et al [43] used two types of artificial substrates (basalt and concrete) with rough surfaces. Sedano et al [59] directly compared natural and artificial substrates, but only one type of artificial substrate was used (rip-raps). The present study was conducted to test whether there was a significant difference between various types of artificial and natural substrates.…”

New horizons for the Panhellenic Symposium of Oceanography & Fisheries

“…Section 2: Aquatic ecology • Sedano et al (2019) attempt to compare the structure between sessile communities associated with hard natural and artificial substrates in Crete (Eastern Mediterranean). These communities are proved to be different in many respects.…”