Assessing the effect of Amphistegina lobifera invasion on infralittoral benthic foraminiferal assemblages in the Sicily Channel (Central Mediterranean).

This article documents, through a quantitative approach, the negative effect of the highly invasive species Amphistegina lobifera Larsen, 1976 on native benthic foraminiferal assemblages of coastal areas in the Sicily Channel (Central Mediterranean). A nested sampling design was applied through the comparison of benthic foraminiferal community structure across three areas that are known to be at different stages of invasion (i.e. Maltese Islands - advanced, southern Sicily - medium, and eastern Sicily - early). Results suggested that both diversity and richness of benthic foraminiferal community from the Maltese Islands were strongly modified by increased abundances of A. lobifera. In contrast, this phenomenon is less evident in southern and eastern Sicily, where the invader displayed lower abundances and the community structure was more diversified. Collected data also allowed for predicting what could happen in the near future in the whole Sicily Channel, as well as in the rest of the Mediterranean Sea.

First attempt to quantify microplastics in Mediterranean Sabellaria spinulosa (Annelida, Polychaeta) bioconstructions.

This work focuses on the arenaceous reefs by the polychaete Sabellaria spinulosa and addresses microplastics pollution. The main aim is to assess microplastics amount in a bioconstruction located in the Adriatic coast of Italy (Mediterranean Sea) through a comparative approach: sea-floor sediment and bioconstruction samples were analysed to quantify microplastics absolute abundance in both substrates. A total of 431 MPs were found in the investigated substrates: respectively 85 % fibers and 15 % fragments. Multivariate analysis indicates that MPs within bioconstruction occur in higher abundances and with different morphologies than in sediment samples. The analysis of bioconstruction polished sections allowed for observation of MPs agglutinated in their original position: higher concentration is reported in inter-tube areas. Results suggest that physical characteristics of MPs could play a key-role in bioconstruction inclusion processes and raise questions on effective role of sabellariid bioconstructions as a trap for this pollutant in the littoral environment.

Selection or random picking? Foraminiferal tests in Sabellaria alveolata (Linnaeus, 1767) bioconstructions.

This work investigates whether the honeycomb worm Sabellaria alveolata (Polychaeta) actively selects foraminiferal tests to build its arenaceous bioconstructions and if the tests are chosen based on a defined criterion. To this purpose, both foraminiferal content and structure of communities were compared across samples of bioconstructions and samples of neighbouring sediment collected from two sites of southern Sicily (Central Mediterranean). Results document a higher concentration of foraminiferal tests within the tubes than in sediment, with a clear preference for biconvex and spherical morphologies. We hypothesize that the high proportion of biconvex and spherical tests in the bioconstruction is probably due to the active selection operated by the polychaete combined with the different buoyancy of foraminiferal tests kept in suspension by the wave motion. Among the grains agglutinated in the tubes, we also observed sporadic specimens of Amphistegina lobifera Larsen, a non-indigenous foraminifer native to the Red Sea.