On-board Diary: Ausias March Seamount
Author: Ricardo Aguilar
Date: September 25, 2007
After a few days in Formentera to prepare to ROV for filming the seamounts of the channel of Mallorca, we start work once again. Yesterday, we took advantage and the divers were able to get some images of groupers (Epinephelus marginatus), striped groupers (Epinephelus costae), mottled groupers (Mycteroperca rubra), barracudas (Sphyrna viridensis) and other medium and large-sized fish.
Today, we began working with the robot on Ausias March seamount, between 80 and 100 meters depth. The sea bed is mainly comprised of alternating coralline and maerl, with some sandy areas and a few small rocks. The most common species of fish we find are the triglids (Aspitrigla cuculus, Trigloporus lastoviza), some small-spotted catsharks (Scyliorhinus canícula), seabass (Serranus cabrilla), etc. We also spot an African armoured searobin (Peristedion cataphractum) atop the maerl, when all the searobins we had seen up to then had been on sandy or muddy sea beds.
There are many sponges and we are lucky enough to find another carnivorous sponge (Asbestopluma hypogea). This time, it was also atop a sea bed with rhodolithes and very exposed, at approximately 100 meters depth. It is the second one found in Spanish waters, after the one we identified in Seco de los OIivos (Almeria).
We carried out the afternoon dive in Les Olives. This time, though, we went to the southern area where the current is not as strong. We were able to descend to 274 meters depth, where we’ve found a sea bed made up of very fine sand with redfish (Helicolenus dactylopterus) and boarfish (Capros aper), but also a few triglids (Lepidotrigla cavillone) and a couple of species of deep-sea fish from the Gadiforme order. We must carefully study them, but the smallest one is possibly Gadiculus argenteus, while the other looks like a grenadier or deep-sea cod. Although the most common species found here are hundreds of dead or dying Pelagia noctiluca jellyfish, the ones that invaded much of the Mediterranean coast.
As we approached the edge of the top of the seamount, the rocky bottom became more apparent. We spot some holothurians (Holothuria sanctori and H. tubulosa), large scorpionfish (Scorpaena scrofa) and crustaceans (Portunus hastatus and Paramola cuvieri). All of a sudden, some strange, twisted shapes appear before our eyes. They are black corals that measure more than 50 centimeters in height. It is the species Leiopathes glaberrima with its shiny black trunk and its yellowish-green and redish-orange “branches”. What's interesting are the anthozoans growing on top of the coral, such as the sea coral Gerardia savaglia and a small, white gorgonian we have yet to identify. In the surroundings, armies of small shrimp (Plesionika narval) swim from one side to another.
After the dive, we set sail towards the Ebro river delta…