Marine caves of the Southern Tyrrhenian Sea: a First Census of Benthic Biodiversity

Esposito V,Scotti G,Andaloro F,Chemello R,Romeo T,Consoli P

doi:10.4172/2155-9910.1000238

Abstract

This is the first paper documenting research on a selection of marine caves located along the coast of Capo Milazzo in the southern Tyrrhenian Sea. Three submarine and one semi-submerged caves were surveyed and sampled using underwater photo sampling. Surveys have only taken into account the sessile species belonging to the main taxa: Porifera, Anthozoa, Bryozoa and Polychaeta. Diversity indices and abundances were calculated for three sections within each explored cave: the Entrance Zone, Intermediate Zone and Bottom Zone. The richest group was Porifera with 21 taxa, followed by cnidarians, (Anthozoa), with 8 taxa, Polychaeta (5 taxa), and Bryozoa (5 taxa). Among Porifera, the presence of Petrobiona massiliana, a protected species according to SPA/BIO Protocol and the Bern Convention, must be highlighted. The encrusting forms were dominant in the Bottom Zone, the massive forms in the Intermediate Zone and the arborescent forms in the Entrance Zone. Generally, the percentage coverage of each morphological group showed a decline in the Intermediate Zone and a general increase in the Dark Zone within each cave. The S, H’ and J values showed different trends in the five caves. These differences, also evidenced by Permanova analysis, depend on the topographic specificity of each cave which, in turn, affects the gradients of the biotic and abiotic parameters. Finally, no horizontal gradient of rarefaction of the benthic sessile fauna has been detected. This study represents an important step for the management and conservation practices of these fragile ecosystems, especially in view of the forthcoming establishment of the Marine Protected Area.

Highlights

According to Annex 1 of the ‘Habitats’ EC Directive 92/43, the submerged and semi-submerged caves, are natural habitats of community interest
Habitat and associated species, have been included in the Action Plan, (AP), regarding the conservation of habitats and species associated with seamounts, underwater caves and canyons, aphotic hard beds and chemo-synthetic phenomena in the Mediterranean Sea [1]
Since January 2014, the submerged part of the promontory of Capo Milazzo was included in the list of the Marine Protected Areas of Gathering, (Law 27 December 2013, n. 147 ordinary supplement n. 87 to the Official Gazette n. 302 of 12.27.2013), and from August 2014, following the economic, social and environmental investigations commissioned by the Italian Ministry of the Environment and Protection of Land and Sea to ISPRA, Capo Milazzo was proposed as an MPA

Summary

Introduction

According to Annex 1 of the ‘Habitats’ EC Directive 92/43, the submerged and semi-submerged caves, (code 8330), are natural habitats of community interest. Habitat and associated species, (semidark cave habitats), have been included in the Action Plan, (AP), regarding the conservation of habitats and species associated with seamounts, underwater caves and canyons, aphotic hard beds and chemo-synthetic phenomena in the Mediterranean Sea [1]. The AP asserts (B.2–Setting up MPAs) that “the institution of a Marine Protected Area intended to permit more efficacious conservation of these dark assemblages must be based on the identification of emblem sites on the basis of the criteria: uniqueness or rarity, particular importance for species biological stages, importance for threatened, endangered or declining habitats or species, vulnerability and reduced recuperative capacity after disturbance, biological productivity, biological diversity and naturality” [1]. Management action will need to be evaluated in order to reduce and prevent the impact of recreational divers on the benthic community [8,9]

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