First faunistic results on Valencia (Cresques) Seamount, with some ecological considerations

Abstract

The living and dead fauna of Valencia Seamount, a deep promontory in the middle of the Balearic Basin which summit is at ca. 1100 m depth, is described by first time based in a rock dredge perfomed in a sedimentary area of the summit Mount. Surface-feeder polychaetes (the Paraonidae Levinsenia gracilis and Terebellidae as dominant), and taxodont bivalves (Ledella messanensis and Yoldiella ovulum) were the main species of benthos. We found alive remains of the bamboo coral Isidella elongata, a vulnerable, habitat-forming species in the deep Mediterranean. Benthos density was low (0.6 organisms/2 dm3 mud). Thanatocoenosis evidenced a rather moderate diversity of benthic bivalves (11 species) and gastropods (9 species) also dominated by surface deposit feeders. Fish (identified/quantified from sedimented otoliths) showed diversified and abundant mesopelagic fauna, mainly Myctophidae. More interestingly, we highlighted among benthopelagic fish the occurrence of recruits of Merluccius merluccius, Micromesistius poutassou, or Hymenocephalus italicus, all species that live in the neighboring slopes of the Iberian Peninsula and the Balearic Islands at quite shallower depths (at 100-700 m) than their distribution in the Valencia Seamount summit (1102–1130 m) based on the deposited otoliths found. Some ecological aspects were discussed and the necessity to consider the deep Valencia Seamount as a potential area that should be under protection.