Caulerpa racemosa impact on phytobenthic/macro algal communities at Tad-Debbra (Marsaxlokk)

Abstract

This investigation has been carried out in the light of several studies conducted around the Mediterranean on Caulerpa racemosa, where it has been known to have replaced the native sea grass meadows of Posidonia oceanica, which prompted significant change in the benthic macrofauna and caused a decrease in the abundance of gastropods and crustaceans. An attempt to observe any indications of impact by Caulerpa racemosa established in the Tad-Debbra area in Marsaxlokk Bay was planned. Sampling was carried out during five different sampling periods over a one year three month time span. Within the same area of Tad-Debbra three distinctly different zones were sampled; a zone with C. racemosa and other macro algae over rocky substrata, a zone with C. racemosa, macro algae and P. oceanica and a zone with P. oceanica and other macro algae without the presence of C. racemosa. This study has provided insight on a local invasion of C. racemosa on local phytobenthic/macroalgal communities mainly on rocky substrata and matte with P. oceanica. An attempt to present a better understanding of the local situation in regard of the susceptibility local habitat to invasions by alien species as C. racemosa was made. Observations indicated a lower percentage composition of P. oceanica where C. racemosa was present in comparison to areas where C. racemosa was not present.