Asteroids and Ophiuroids associated to sponge aggregations as a key of marine habitats. A compared analysis between Avilés Canyons System and Le Danois Bank

English. This study analyzes the fauna composition of the community of brittle and seastars associated with sponge aggregations located in Avilés Canyons System andEl Cachucho, Marine Protected Area (MPA). Diverse sampling methods were useddepending on bottom morphology, such as rock dredges and specific samplers forsedimentary bottoms, mainly beam trawl models. These banks are made up of spongeand coral species that build a very appropriate substrate for the proliferation of benthicspecies, which together create Vulnerable Marine Ecosystems that are highly relevantfor management and conservation. Among these benthic species, echinoderms are ofgreat interest due to their value as indicators of good habitat. In total, 1261 specimenswere collected (934 brittle stars and 327 starfishes), belonging to 42 species (28ophiuroids and 14 asteroids) from INDEMARES AVILÉS, ECOMARG, and SponGESproject surveys. Specimens were distributed among four sponge aggregations (F: fields)that were considered according to the sponge records obtained in the same stations(36). These fields were defined and named based on the five most common spongespecies: Aphrocallistes beatrix and Regadrella phoenix (F1: Avilés Canyon); Pheronemacarpenteri (F2: Intraslope basin of Le Danois Bank); Asconema setubalense (F3: LeDanois Bank); and Neoschrammeniella aff. bowerbankii (F4: Corbiro Canyon). Faunisticresults show that Ophiactis abyssicola (55.55% occurrence), Brisinga endecacnemos,Ophiolycus purpureus, and Peltaster placenta (33.33%) were the most frequentlyfound species in F1; Psilaster andromeda (80%), Pseudarchaster parelii (60%), andNymphaster arenatus (46.67%) in F2; Ophiura carnea (71.43%) and Ophiacanthasmitti (42.86%) in F3; and Ophiacantha densa, and Henricia caudani (100%) in F4.The asteroid and ophiuroid species collected seem to be composed of four differentcommunities that fit to areas with particular morphological and biological features,related to the presence of species specialized in the use of the resources they can find there. In general, the abiotic factor controlling this structure is depth. Thisassemblage structure, which favors the dissimilarity between the canyons and thebank, is not so clear, since the deepest stations are located on the intraslope basinof El Cachucho, Marine Protected Area (MPA), therefore, using it a priori could lead tomisunderstandings. Once the structure of the echinoderm community was known, wecompared the expected and obtained results to analyze evidence which should provethe existence of any association between echinoderms and sponges, which enabled usto refute the incongruous hypothesis.

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