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Observations of organic falls from the abyssal Clarion-Clipperton Zone in the tropical eastern Pacific OceanOrganic falls can form nutrient-rich, ephemeral hotspots of productivity and biodiversity at the deep-sea floor, especially in food-poor abyssal plains. We report here the first wood falls and second carcass fall recorded from the Clarion-Clipperton Zone in the tropical eastern Pacific Ocean, an area that could be mined for polymetallic nodules in the future. A small cetacean fall in the mobile-scavenger stage likely recently arrived on the seafloor was observed, whereas most of the wood falls were highly degraded. There were multiple species in attendance at the wood falls including organic-fall specialists such as Xylophagaidae molluscs. Many of the taxa attending the carcass fall were known mobile scavengers that regularly attend bait parcels in the Pacific Ocean. These results further confirm that wood falls can occur at large distances (>1450 km) from major land masses, providing an adequate supply of wood to the abyssal seafloor for colonization by wood-boring molluscs and associated fauna. Organic falls may be regionally abundant and are likely to influence species and habitat diversity in the abyssal areas of the Clarion-Clipperton Zone.
Taxonomy and phylogeny of mud owls (Annelida: Sternaspidae), including a new synonymy and new records from the Southern Ocean, North East Atlantic Ocean and Pacific Ocean: challenges in morphological delimitationSpecies delimitation in sternaspid polychaetes is currently based on the morphology of a limited suite of characters, namely characters of the ventro-caudal shield—a unique feature of the family. Sternaspid species description has increased rapidly in recent years; however, the validity of the shield as a diagnostic character has not been assessed through molecular means. This study performs the largest molecular taxonomy of Sternaspidae to date, using the nuclear gene 18S, and the mitochondrial genes 16S and cytochrome oxidase subunit I (COI) to assess phylogenetic relationships within the family, to reassess the placement of Sternaspidae within the wider polychaete tree and to investigate the effectiveness of the shield as a diagnostic morphological character. This study includes many new records and reports Sternaspis affinis Stimpson, 1864 from USA Pacific coastline and genetic connectivity between specimens identified as Sternaspis cf. annenkovae Salazar-Vallejo & Buzhinskaja, 2013 from off southeastern Australia and specimens identified as Sternaspis cf. williamsae Salazar-Vallejo & Buzhinskaja, 2013 from the northwestern Pacific. In addition, we investigate material identified as Sternaspis cf. scutata (Ranzani, 1817) in the English Channel and compare with S. scutata through both molecular and morphological means. We further perform a detailed morphological and molecular investigation of new sternaspid material collected from the Southern Ocean and Antarctic Peninsula and regard Sternaspis monroi Salazar-Vallejo, 2014 syn. n. as a junior synonym of Sternaspis sendalli Salazar-Vallejo, 2014, two species recently described from the region, raising questions concerning the validity of current morphological delimitation.