Finally, the ROV technicians couldn’t solve the problem and decided the best option was to take it to Barcelona, because it would be easier to solve technical problems there. Joan and Manuel left with the ROV and we continued our work with the divers in shallow waters.
We started the day with a dive off the Callejos de Bamboa seamount atop large blocks of rock on a sandy-muddy seabed.
During the dive, we documented an abundance of gorgonians, spider crabs Maja squinado, bryozoans Pentapora foliácea, pouts Trisopterus luscus, cuckoo wrasse (Labrus bimaculatus) and scorpionfish (Scorpaena sp.). On the substrate, the alga Peyssonnelia sp. was an intense red.
In the muddy area, we found female specimens of Bonellia viridis at 29 meters depth. The female of this species is a green, contractile organism that measures 15 cm length and is not protected by any kind of tube. It can stretch itself and reach various meters in length. The male, however, is usually not longer than 3 mm and lives inside the female as a parasite. When a specimen of this species is born, it is asexual. If it doesn’t find a female, it turns into one. But if it does find a female, it seeks refuge inside it and develops into endosymbiont male.
The divers also documented a male Symphodus baillonii building a nest in which the females, which are part of a harem, will subsequently lay their eggs.
The second dive, off Saltacaballos Point, covered a rocky area with strong presence of algae on the top and overhangs. Amongst the species of algae, we documented Peyssonellia, Mesophyllum, Cystoseira, Gelidium, Zanardinia, Falkenbergia and Codium. On the ledges, we spotted many invertebrates, particularly the nudibranch Cadlina pellucida on top of a sponge and the prawn Periclimenes sagittifer living in symbiosis with the anemone Anemonia sulcata. In a cave, they also photographed a leopard-spotted goby Thorogobius ephippiatus, which is not frequently found.
After the dives, we surveyed the Castro Verde seamount up to 325 meters depth. This seamount, some 10 nautical miles from Castro Urdiales, is a traditional fishing area. The profile showed us several interesting walls for diving with the ROV, but since it’s not working right now, we left with the hopes of returning after our trip to the Basque Region.
It was precisely off this seamount that we sighted a group of 6 common dolphins (Delphinus delphis), all adults, in an area where the temperature was approximately 18.7ºC with a depth of 120 meters. We watched them for almost an hour as they were feeding, swimming around the seamount.
We docked at the port in Getxo.