Census of biodiversity in marine caves of the eastern Mediterranean Sea

Abstract

Scientific information on the biodiversity of marine caves in the eastern Mediterranean is limited, especially when considering the extensively studied caves of the north-western and central Mediterranean. Aiming to enhance current knowledge regarding cave communities, this study represents a first assessment of the marine cave biota of the eastern Mediterranean, as defined by the European Union's Marine Strategy Framework Directive (MSFD). Information retrieved from an extensive overview of relevant scientific documents was combined with original data recorded from 23 marine caves in the north-eastern Mediterranean. Our results report a total of 520 taxa recorded in eastern Mediterranean marine caves to date, the majority of which are sponges, polychaetes, rhodophytes, bivalves, fishes, and gastropods. These include several protected, endemic and alien species. However, not all taxonomic groups from different areas have been equally investigated and future studies are expected to increase the number of endemic and alien species. The observed general trend is that the reported species number is generally related to sampling effort and scientific expertise. The most well-studied marine cave communities in the eastern Mediterranean are those of the Aegean Sea (especially its northern sector), which presented the highest number of species, followed by those of the Levantine. Furthermore, our research in Aegean caves revealed numerous new records for the marine cave fauna of the eastern basin, while several species are reported for the first time in a marine cave habitat. The critical need for further scientific research, monitoring, and conservation of this unique ecosystem was highlighted by (i) the presence of certain species endemic to the eastern Mediterranean coupled with a high proportion of alien species, especially in the Levantine Basin, and (ii) marine cave habitat availability in isolated insular areas of the eastern Mediterranean.

Caves Biodiversity in the Marine Area of Riviera d'Ulisse Regional Park, Italy: Grotta del Maresciallo Overview

“…of morphology, length and presence/ absence of light in the innermost portions. Indeed, the calculated taxa percentage contribution of the "Grotta del Maresciallo" biodiversity integrates the Mediterranean's evaluation already calculated and reported in literature [36], showing the taxa of "Grotta del Maresciallo" result to be copius for Chordata, Echinodermata, Arthropoda in relation to the biodiversity found in caves of the central Mediterranean sea (shown in green), and in general in all the caves of the Mediterranean [12]. The presence of abundant sponges (see Table 1) on overhanging ledges in these caves, but not observed elsewhere, indicates that even in deep waters, caves offer a preferred biological niche for some animals.…”

“…Still there can be a biological pollution also, due to new thermophilic and/or tropical species [5][6][7]. For these reasons a continuous monitoring action is necessary to provide information about the costal structure, sea level changes, spatio-temporal species in the caves performed by a census made and supported by professional divers and molecular techniques [8][9][10][11][12]. In this optic the census and the identification represent an important step to establish the abundance/rarity degree of the marinea species [13,14], as well to detect possibly cryptic species and even to describe new species [15][16][17].…”

“…The biodiversity and community structure in the north-western and central Mediterranean caves have been widely studied, while still few information are available for the 738 marine caves in the eastern Mediterranean [7,19,20]. However, the marine cave biodiversity list was also checked for the presence of alien species [12] in relation to their worst effect [21]. As reported in the inventory by Darling and Blum [22], organism morphology for micro-and meio-fauna can require the expertise of multiple taxonomists for complex communities, thus significantly elevating costs.…”

Assembling Ecological Pieces to Reconstruct the Conservation Puzzle of the Aegean Sea

“…Additional information was obtained during regional biodiversity assessments (Gerovasileiou et al, 2015), interviews and questionnaires with divers, as well as diving surveys conducted during the present study.…”

World Register of marine Cave Species (WoRCS): a new Thematic Species Database for marine and anchialine cave biodiversity

“…All taxa in this database were cross-checked and taxonomically updated using WoRMS. The database has been already used as a source of information for studies on diversity of Porifera (Gerovasileiou and Voultsiadou 2012), marine cave biota of the eastern Mediterranean (i.e., Aegean and Levantine ecoregions) (Gerovasileiou et al 2015), and non-indigenous species in Mediterranean caves (Gerovasileiou et al 2016a ).…”