Scientists discover over 1,500 mounds with corals off Marsaskala

The Univeristy of Malta (UM) said that scientists from the Department of Geosciences at the University of Malta discovered more than 1,500 enigmatic mounds off Marsaskala, on an area of seafloor ten times the size of Comino.

“The density of these features, which consist of rocky outcrops with a mounded shape, is unparalleled and definitely not what we would have expected in this part of the Mediterranean Sea. Most similar structures we know of are from tropical waters and are quite different from the ones we found offshore Malta." said Prof. Aaron Micallef, the lead scientist on the project.

UM said that the mounds are on average 20 metres wide, several metres high, and are found in dense clusters at seafloor depths ranging between 60 and 120 m. It added that the origin is unclear, although they were possibly formed by either seepage of groundwater or wave action when sea-level was lower in the past.

“The most fascinating aspect of these mounds is that, by rising above the sediment seafloor, they provide a base for a wide range of organisms, many of them endangered and protected by international law,” added Micallef.

The surfaces of the mounds, which consist of fossilised algae and tubeworms, provide a home to black corals, gorgonians, colourful sea slugs and sea urchins.

“When we think of reefs, this isn’t usually what we think of [...] but at these depths, light is limited and this is the type of biological communities one should expect. These are delicate organisms, growing slowly over hundreds and even thousands of years,” said Dr Or Bialik, lead author of the study.

The university also remarked that the scientists identified extensive trawl marks, formed by dragged anchors or bottom fishing activities, located in the same area as these mounds. It said that it appears that trawling activities have destroyed or damaged mounds and their fragile ecosystems.

This study was funded by Marie Curie Actions, with scientists from the University of Milano Bicocca and the National Oceanography Centre (UK).