Biodiversité et signification écologique des ectosymbiontes des Cidaridae antarctiques (Echinodermata :Echinoidea)

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

On a new species of apodid, Taeniogyrus magnibaculus n. sp. (Echinodermata, Holothuroidea), from Antarctica, living on the spines of cidarid echinoids

The present paper describes a new apodid holothuroid living on the spines of cidarid echinoids, This new species is characterised by large ossicles and especially by huge rods in the tentacles. A table summarises the characteristics of the known Taeniogyrus species. © Springer-Verlag 2004.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Biodiversity, phylogeny and trophodynamics of amphipod crustaceans in the Antarctic deep sea

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Biodiversité et signification écologique des ectosymbiontes des Cidaridae antarctiques (Echinodermata : Echinoidea)

Les oursins cidaridés caractérisés par l absence d épithélium sur leurs piquants primaires, procurent une grande diversité de substrats pour les organismes sessiles, particulièrement en Antarctique. L inventaire des espèces symbiotiques montre une dominance nette des spongiaires et des bryozoaires et que la diversité des ectosymbiotes fluctue en fonction des espèces hôtes et de la profondeur. Par contre, la distance entre les stations n influence pas la structure et la composition des communautés symbiotiques. Une analyse morphologique des piquants a éte réalisée afin de connaître l influence de leur forme sur les communautés symbiotiques. Les résultats suggèrent que la colonisation symbiotique est directement liée aux paramètres dimensionnels des piquants (taille & spinosité). Les communautés symbiotiques diffèrent sensiblement de celles des tillites (roches environnantes). Contrairement aux symbiotes, les faunes portées par les tillites sont relativement semblables entre les stations.Cidaroid sea urchins provide a wide range of substrates for sessile organisms, particularly in Antarctic where the availability of hard substrate is a limiting resource. An inventory of Antarctic cidaroid ectosymbionts showed that 62% of ectosymbionts are bryozoans and sponges. Ectosymbiotic specific diversity varied with the host species and depth, but the distance between sampling sites did not affect community structure and composition. Two sets of parameters were defined to determine the influence of cidaroid spine shapes on symbiotic communities. Morphometric analyses showed the existence of a gradient between oral, ambital and apical spines. Symbiont colonization was directly related to dimensional parameters of the spines. Finally, symbiotic communities associated with cidaroids strongly differ from the tillites-associated ones. Taking cidaroid-associated communities into account is therefore necessary to get an exhaustive picture of the Antarctic benthic biodiversity.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

Ectosymbiosis is a critical factor in the local benthic biodiversity of the Antarctic deep sea

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Comparative biodiversity of ectosymbionts in two Antarctic cidaroid echinoids, Ctenocidaris spinosa and Rhynchocidaris triplopora

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Microstructures of Antarctic echinoids spines: diversity of shapes and ectosymbionts attachments

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Macro- and megabenthic assemblages in the bathyal and abyssal Weddell Sea (Southern Ocean)

The assemblages inhabiting the continental shelf around Antarctica are known to be very patchy, in large part due to deep iceberg impacts. The present study shows that richness and abundance of much deeper benthos, at slope and abyssal depths, also vary greatly in the Southern and South Atlantic oceans. On the ANDEEP III expedition, we deployed 16 Agassiz trawls to sample the zoobenthos at depths from 1055 to 4930m across the northern Weddell Sea and two South Atlantic basins. A total of 5933 specimens, belonging to 44 higher taxonomic groups, were collected. Overall the most frequent taxa were Ophiuroidea, Bivalvia, Polychaeta and Asteroidea, and the most abundant taxa were Malacostraca, Polychaeta and Bivalvia. Species richness per station varied from 6 to 148. The taxonomic composition of assemblages, based on relative taxon richness, varied considerably between sites but showed no relation to depth. The former three most abundant taxa accounted for 10-30% each of all taxa present. Standardised abundances based on trawl catches varied between I and 252 individuals per 1000 m2. Abundance significantly decreased with increasing depth, and assemblages showed high patchiness in their distribution. Cluster analysis based on relative abundance showed changes of community structure that were not linked to depth, area, sediment grain size or temperature. Generally abundances of zoobenthos in the abyssal Weddell Sea are lower than shelf abundances by several orders of magnitude

(Tables 1, 3) Details of Agassiz trawl stations and numbers of specimens per macro- and megazoobenthic taxon collected during POLARSTERN cruise ANT-XXII/3 (ANDEEP III)

The assemblages inhabiting the continental shelf around Antarctica are known to be very patchy, in large part due to deep iceberg impacts. The present study shows that richness and abundance of much deeper benthos, at slope and abyssal depths, also vary greatly in the Southern and South Atlantic oceans. On the ANDEEP III expedition, we deployed 16 Agassiz trawls to sample the zoobenthos at depths from 1055 to 4930 m across the northern Weddell Sea and two South Atlantic basins. A total of 5933 specimens, belonging to 44 higher taxonomic groups, were collected. Overall the most frequent taxa were Ophiuroidea, Bivalvia, Polychaeta and Asteroidea, and the most abundant taxa were Malacostraca, Polychaeta and Bivalvia. Species richness per station varied from 6 to 148. The taxonomic composition of assemblages, based on relative taxon richness, varied considerably between sites but showed no relation to depth. The former three most abundant taxa accounted for 10-30% each of all taxa present. Standardised abundances based on trawl catches varied between 1 and 252 individuals per 1000 m2. Abundance significantly decreased with increasing depth, and assemblages showed high patchiness in their distribution. Cluster analysis based on relative abundance showed changes of community structure that were not linked to depth, area, sediment grain size or temperature. Generally abundances of zoobenthos in the abyssal Weddell Sea are lower than shelf abundances by several orders of magnitude