Marine shelled molluscs from two locations in the Maltese Islands - a checklist

Abstract

Climate change and manifold other anthropogenic influences are the main driving factors for changes in marine ecosystems. Characterising these changes is of great interest and can be made possible through the adoption of marine shelled mollusca as bioindicators. Malta is renowned for its rich diversity of mollusc species, including rare and endemic ones. So, we analysed mollusc shell grit from two locations (St. Pauls Island/Selmunett Island and Marsaxlokk) to provide a species baseline list for future investigations. We identified a total of 7662 parts of marine shelled mollusca. 115 species were found at St. Pauls Island and 45 species at Marsaxlokk, belonging to a total of 60 families (16 at both locations). To make both samples comparable, despite differences in sampling efforts, we formulated an individual-based species extrapolation curve for each location. With this, we calculated an estimated total species number of 134 at St. Pauls Island and of 49 at Marsaxlokk, for a set threshold of 6000 individuals, indicating a considerably lower mollusc diversity at the second location, putatively the result of higher human disturbance levels at the same location. The substantial differences in mollusc species composition between the two localities, despite the small geographical distance between the two, further underscores the importance of further related research.