Mesophotic Depth Biogenic Accumulations (“Biogenic Mounds”) Offshore the Maltese Islands, Central Mediterranean Sea

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: This is version 4 of this Preprint.


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Or M. Bialik, Andrea Giulia Varzi, Ruth Duran Gallego , Timothy Le Bas , Adam Gauci, Aaron Micallef , Alessandra Savini


The mesophotic domain is a poorly explored part of the oceans, notably in the Mediterranean Sea. Benthic communities in these depths are not well documented and as such are under higher risk from anthropogenic impacts. Hard substrate habitats in this depth window are not common and are a key ecotope. The Malta Plateau in the central Mediterranean, which is characterized by low sedimentation rates, offers a potentially unexplored domain for these features. Bathymetric and backscatter data offshore of the eastern coast of the island of Malta were used to identify > 1,700 small structures in mesophotic depths. These structures were verified to be biogenic mounds by dives. The mounds extend from several meters to tens of meters in diameter and occur in two main depth windows −40 to 83 meters below present sea level (mbpsl) and 83–120 mbpsl—each formed probably in a different stage during the last glacial cycle. The mounds are composed of interlocking bioconstruction by encrusting organisms and are colonized by sponges and various cold water corals (most of which are protected; e.g., Madrepora oculata). This unique and important habitat is currently under grave threat by human activity, most immediately by trawling and anchoring activity.



Geology, Geomorphology, Other Earth Sciences, Other Environmental Sciences


Malta Plateau, Malta Plateau, Biogenic mounds, Reefs, Natural heritage, Coralline algae, Trawl marks, Seafloor mapping, Reefs, Natural heritage, Coralline algae, Trawl marks, Seafloor mapping


Published: 2021-10-28 20:12

Last Updated: 2022-03-16 15:25

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CC BY Attribution 4.0 International

Additional Metadata

Data Availability (Reason not available):
Bathymetric data is own by national governament and is restricted.

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