Polychaete Diversity Related to Different Mesophotic Bioconstructions along the Southeastern Italian Coast

Maria Flavia Gravina,Cataldo Pierri,Maria Mercurio,Adriana Giangrande,Carlotta Nonnis Marzano

doi:10.3390/d13060239

Abstract

In the different mesophotic bioconstructions recently found along the Southeastern Italian coast, polychaetes have been proved to show high species richness and diversity, hitherto never investigated. In the present study, the species composition and functional role of polychaete assemblages were analysed; the updated key to identification of the Mediterranean species of genus Eunice was presented and some taxonomic issues were also discussed. On the total of 70 species Serpulidae and Eunicida were the dominant polychaetes. Facing similar levels of α-diversity, the polychaete assemblages showed a high turnover of species along the north-south gradient, clearly according to the current circulation pattern, as well as to the different bioconstructors as biological determinants. Indeed, Serpulidae were dominant on the mesophotic bioconstructions primarily formed by the deep-sea oyster Neopycnodonte cochlear, while the Eunicida prevailed on the mesophotic bioconstructions mainly built by scleractinians. Lastly, the record of Eunice dubitata was the first for the Mediterranean and Italian fauna and proved this species to be characteristic of mesophotic bioconstructions.

Highlights

IntroductionMediterranean polychaetes are proved to be good bioindicators of environmental conditions and ecological status both on sedimentary and rocky bottoms [1,2,3]
Eunice dubitata constitutes a new record for the Italian fauna and amends the checklist [41]
Polychaete assemblages associated with the different mesophotic bioconstructions investigated off the Southeastern Italian coast, Apulia, proved to be very rich and diverse in species number and composition, with 70 species recorded overall, most of which are included both in the family Serpulidae and in the order Eunicida

Summary

Introduction

Mediterranean polychaetes are proved to be good bioindicators of environmental conditions and ecological status both on sedimentary and rocky bottoms [1,2,3]. Such results are achieved following investigations especially in shallow habitats, as well as in circalittoral habitats where coralligenous formations occur [4,5,6]. The coralligenous is a characteristic Mediterranean biocoenosis which is an object of detailed studies, due to its role in shaping the seascape, formed by perennial algae and animal organisms with consistent calcareous concretions in sciaphilic environments, from 20 to 120 m depth [7,8,9,10,11]. The habitats located in the twilight zone, so-called “mesophotic zone” ranging from 30–40 to 150 m depth, are currently under study

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