ATIMO VATAE, BENTHEDI, BIOMAGLO, MAINBAZA, MIRIKY, Walters Shoal

BENTHAUS, MUSORSTOM 9, TARASOC

Based on the specimens collected during three deep-sea cruises, and deposited at the Muséum National d’Histoire Naturelle (MNHN) in Paris, we analysed the diversity of benthic communities within the EEZ of French Polynesia. The literature and the MNHN database allowed us to inventory 471 species of invertebrates, among which 169 were newly described. We mainly found data for Mollusca, Crustacea, Brachiopoda and Crinoidea. We also found samples from other taxa, which still remain unidentified within the collections of the MNHN. Although this inventory is incomplete, we demonstrate that the deep waters of French Polynesia host unique benthic communities and endemic species. Using diversity and multivariate analyses, we show that the deep-sea benthic communities are structured by depth, habitats, geography and also by the presence of polymetallic crust. Furthermore, by focusing on the molluscs of the central area of French Polynesia, we show that the spectrum of shell size differs among deep-sea habitats. Specifically, shells tend to be smaller on encrusted seamounts than on island slopes. Together with the size range of organisms, low abundance, rarity and endemism designate these habitats as sensitive. These results should thus be taken into account in the evaluation of the expected impact of mining activities on biological communities.

BENTHAUS, MUSORSTOM 9, TARASOC

Delineating biogeographical regions can provide important insights into the processes shaping large‐scale species distribution patterns. Here we aimed to 1) identify global marine benthic biogeographical regions for ophiuroids extending from shallow waters to the deep sea and 2) quantify the importance of contemporary environmental conditions and geological features in shaping the delineated biogeographical regions. We delineated marine benthic biogeographical regions using a bipartite network analysis applied to a historical dataset of brittle stars. We then examined the faunal exchanges between the regions, and applied random forest models to evaluate the relative role of contemporary environmental conditions and tectonic configuration underlying the proposed biogeographic scheme. We propose ten main large biogeographical regions across the benthos. The biogeographical regions with the highest species richness and endemicity rates were found in the Indo‐Pacific region, Tropical West Atlantic and Southern Ocean, and South America. The key transition regions fall within the subarctic areas of the Pacific and the waters surrounding Southern Australia and New Zealand. Tectonic configuration, surface temperature and salinity were found to be the most important predictors of the ten delineated biogeographical regions. Our biogeographic delineation, including the deep sea, is in partial agreement with those proposed in previous studies. Our results suggest that contemporary environmental conditions (sea water temperature and salinity) strongly influence the modern distribution of ophiuroids, but that plate tectonics left a marked imprint on regional species pools. Future work based on multiple benthic taxa, and with a better understanding of the environmental conditions in the deep sea, are needed to evaluate the robustness of our proposed division.

ATIMO VATAE, AURORA 2007, AZTEQUE, BATHUS 1, BATHUS 2, BATHUS 3, BATHUS 4, BENTHAUS, BERYX 11, BIOCAL, BIOGEOCAL, BIOPAPUA, BOA1, BORDAU 1, BORDAU 2, CHALCAL 1, CHALCAL 2, CORAIL 2, CORINDON 2, DongSha 2014, EBISCO, EXBODI, GUYANE 2014, HALIPRO 1, HALIPRO 2, KANACONO, KANADEEP, KARUBAR, KARUBENTHOS 2, LAGON, LITHIST, MIRIKY, MUSORSTOM 1, MUSORSTOM 10, MUSORSTOM 2, MUSORSTOM 3, MUSORSTOM 4, MUSORSTOM 5, MUSORSTOM 6, MUSORSTOM 7, MUSORSTOM 8, MUSORSTOM 9, NORFOLK 1, PALEO-SURPRISE, PAPUA NIUGINI, SALOMON 2, SALOMONBOA 3, SANTO 2006, SMIB 1, SMIB 2, SMIB 3, SMIB 4, SMIB 5, SMIB 6, TAIWAN 2000, TARASOC, VAUBAN 1978-1979, VOLSMAR, Walters Shoal