A preliminary survey of marine cave habitats in the Maltese Islands

Authors: L. Knittweis, P. Chevaldonné, A. Ereskovsky, P. J. Schembri, J. A. Borg

Corresponding: L. Knittweis (eyla.knittweis@um.edu.mt)

Keywords: Mediterranean marine caves, sciaphilic, cave biota, sessile biotic assemblages, species distribu- tion patterns

Doi: http://dx.medra.org/10.7423/XJENZA.2015.2.06

Issue: Xjenza Online Vol. 3 Iss. 2 - December 2015

The Mediterranean Sea is a hotspot for mar- ine biodiversity. Past studies of Mediterranean marine caves have revealed the unique biocoenotic and ecolo- gical characteristics of these habitats, which are protec- ted by European Union legislation. The Maltese Islands have an abundance of partially and fully submerged marine caves with different geomorphological character- istics, yet there have been no systematic studies on these habitats and their associated species. This study is a rst synthesis of existing information on the biotic as- semblages and physical characteristics of Maltese mar- ine caves. The work combines a review of the available information with a preliminary survey of some marine caves in Gozo, during which several species were recor- ded for the rst time for the Maltese Islands. Character- istic species recorded from local marine caves are high- lighted, including several species of red and brown algae, sessile invertebrates including bryozoans, ascidians and sponges, and mobile forms including crustaceans and sh. A marked zonation from the cave entrance to the inside of the caves was identi ed: photophilic algae at the mouth of the cave are progressively replaced by more sciaphilic species, followed by a middle section domin- ated by sessile invertebrates, and then a completely dark inner section that is mostly devoid of sessile organisms. Several species protected by national and international legislation were found to occur.

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