Intertidal ponds of Messina's beachrock faunal assemblage, evaluation of ecosystem dynamics and communities' interactions

Beachrock can be found in intertidal marine environments worldwide even though the knowledge about its ecological value in Messina’s strait is still quite scarce. In this study, six tidal ponds of Messina’s Beachrock were sampled from October 2016 to October 2017 to investigate the ecological status of the area, biotic and abiotic factors that can influence the faunal assemblage and the relationships among the communities inhabiting the various pools examined. A total of 13399 organisms, belonging to 5 Phyla, were identified by Visual Census. The surveyed stations showed biodiversity values and evenness that depend, above all, from the edaphic features and water exchange of the different tidal ponds. Tidal ponds characterized by a lower water exchange showed a faunal assemblage characterized by the presence of species tolerant to a wide temperature and salinity range, as Mugil cephalus, Clibanarius erythropus and Phorcus turbinatus. The pools with the most water exchange showed the highest abundance and evenness values; while the ponds characterized by hard bottom showed this feature as strong influence on the species composition. A preliminary mathematical study was also carry out to describe, qualitatively, the main mechanisms ruling the interaction between the Clibanarius erythropus and Phorcus turbinatus.