Structure and biodiversity of a Maltese maerl bed: New insight into the associated assemblage 24 years after the first investigation

Maerl beds are biogenic benthic habitats distributed worldwide and known to sustain high productivity and biodiversity levels. In the Mediterranean, the number of studies that have been carried out is limited, and little is known on its real distribution, mostly due to the difficulties of exploring such habitats — Due to the high transparency of Mediterranean waters, maerl can be found at depths of over 50 m making mandatory the use of benthic grabs and ROVs. The last published data from Maltese waters were taken two decades ago. In this present study, we provide new insights on this poorly known habitat, in particular regarding the north western bank, designated as a NATURA 2000 protected area, in which human activities are also carried out, such as blue fin tuna ranching. The objective of this work is to provide information regarding this delicate habitat, especially relevant for future management plans and authorities.