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June 7, 2025

First ROV dive in Tramontana

 

First ROV dive in Tramontana (North Mallorca). We started in a sandy bottom at 80-90 m deep with sparse rhodoliths a lots of sand brittle stars (Ophiopsila aranea), but a few minutes later we started watching some coralligenous outcrops, that were becoming bigger. The coralligenous concretions are fully covered of sponges (Haliclona simulans, H. oculata, H. poecillastroides, Axinella polypoides, A. verrucosa, A, damicornis, A vaceleti, Raspailia viminalis, Siphonochalina sp., Dysidea fragilis, Sarcotragus foetidus, etc.).

These bioconcretions also have many other species living on them, such as bryozoans , sea squirts, hydrozoans, sea stars, sea lilies, octopus, fish… and deep-sea Mediterranean kelps.

It is a beautiful but very fragile ecosystems, with a mosaic seascape. Most coralligenous concretions are not tall and, therefore, easy for trawlers to destroy them.

The second dive is at -95m in a sandy bottom with many biogenic remains. Different species of sea stars, sea urchins, catsharks, bandfish, tube worms, tube anemones, and other typical inhabitants of soft bottoms.

The third dive is in shallower waters (-45 m). Another sandy bottom with large numbers of irregular sea urchins. Seaweeds are also abundant, and the rhodoliths have some dense patches.

Several of the species found on today’s dives are protected (Axinella polypoides, Sarcotragus foetidus, Charonia lampas, Cystoseria zosteroides, Laminaria rodriguezii…)

Tomorrow there will be strong winds from the North-East. We will not be able to work in the same area. We will stay in the West.