The morphological diversity of Osedax worm borings (Annelidia: Siboglinidae)

Marine worms in the genus Osedax, have specialized ‘root’ tissues used to bore into the bones of decomposing vertebrate skeletons and obtain nutrition. We investigated the borings of nine Osedax species, using micro computed tomography to quantitatively describe the morphology of the borings and provide three-dimensional reconstructions of the space occupied by Osedax root tissues inside the bone. Each Osedax species displayed a consistent boring morphology in any given bone, but these differed between bones. In bones where multiple species coexisted there was limited evidence for spatial niche partitioning by Osedax root tissues inside the bones investigated here. The new morphological data may be applied to Osedax traces in fossil bones, showing that borings can be used to indicate minimum species richness in these bones

Onboard Report Of The Hyper-Dolphin/Natsushima Cruise in Sagami Bay (NT10-01)

http://www.godac.jamstec.go.jp/darwin/cruise/natsushima/nt10-01/

Données sur les processus de reproduction et de développement précoce d' un eucaryote thermophile Alvinella pompejana

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

« Pourquoi pas les abysses ? » Le projet de recherche de l’Ifremer pour mieux connaître la biodiversité des fonds marins

Launched in 2016, IFREMER’s program “Why not the abysses ?” (ABYSS) has the objective of drawing up a new inventory of deep-sea biodiversity worldwide. New molecular techniques will be used for access to the so-called “environmental DNA”. DNA strands isolated in water or sediment samples can now be used to detect the species that are living in an environment or used to live there. Based on a systematic description of these samples from all oceans on our planet, this program will help establish a molecular inventory of the diversity of life in the seas, in particular in the depths and abyssal zones – 95% of which have not yet been explored. This in-depth review of this biodiversity sheds light on the factors that determine its distribution and persistence.Lancé en 2016 par l’Ifremer, le projet « Pourquoi pas les abysses ? » (ABYSS) a pour objectif de proposer un nouveau recensement de la biodiversité des grands fonds marins à l’échelle mondiale s’appuyant sur la mise en œuvre des nouvelles techniques moléculaires et devant permettre d’accéder à ce que l’on appelle l’ « ADN environnemental ». Les fragments d’ADN isolés dans des échantillons d’eau ou de sédiments permettent désormais d’accéder à la liste des espèces qui vivent dans un environnement ou y ont séjourné à un moment donné. Basé sur une caractérisation systématique d’échantillons de sédiments et d’eau récoltés dans tous les océans du globe, ce projet a pour ambition de contribuer à l’inventaire moléculaire de la diversité marine, en particulier de celle présente dans le fond des mers et les abysses, des environnements qui à plus de 95 % sont à ce jour restés vierges d’exploration. Cette révision en profondeur de l’étendue de la biodiversité marine nous permettra également d’appréhender les facteurs qui gouvernent sa distribution et sa persistance.Iniciado en 2016 por Ifremer, el proyecto « Pourquoi pas les abysses ? « (ABYSS) tiene como objetivo proponer un nuevo censo de la biodiversidad de los fondos marinos a nivel mundial, apoyándose en la explotación de nuevas técnicas moleculares que permiten acceder a lo que se conoce como el « ADN medioambiental ». Los fragmentos de ADN aislados en muestras de agua o sedimentos permiten acceder a la lista de especies que viven en un entorno o que han vivido allí en un momento dado. Basándose en una caracterización sistemática de las muestras de sedimentos y del agua recolectada en todos los océanos del mundo, este proyecto pretende contribuir al inventario molecular de la diversidad marina ; en particular de la que está presente en el fondo del mar y los abismos, entornos que hasta el día de hoy no se han explorado en más de un 95%. Esta revisión exhaustiva del alcance de la biodiversidad marina nos permitirá también comprender los factores que rigen su distribución y persistencia

Copepod colonization of organic and inorganic substrata at a deep-sea hydrothermal vent site on the Mid-Atlantic Ridge

The few existing studies on deep-sea hydrothermal vent copepods indicate low connectivity with surrounding environments and reveal high endemism among vents. However, the finding of non-endemic copepod species in association with engineer species at different reduced ecosystems poses questions about the dispersal of copepods and the colonization of hydrothermal vents as well as their ecological connectivity. The objective of this study is to understand copepod colonization patterns at a hydrothermal vent site in response to environmental factors such as temperature and fluid flow as well as the presence of different types of substrata. To address this objective, an in situ experiment was deployed using both organic (woods, pig bones) and inorganic (slates) substrata along a gradient of hydrothermal activity at the Lucky Strike vent field (Eiffel Tower, Mid-Atlantic Ridge). The substrata were deployed in 2011 during the MoMARSAT cruise and were recovered after two years in 2013. Overall, copepod density showed significant differences between substrata types, but was similar among different hydrothermal activity regimes. Highest densities were observed on woods at sites with moderate or low fluid input, whereas bones were the most densely colonized substrata at the 2 sites with higher hydrothermal influence. Although differences in copepod diversity were not significant, the observed trends revealed overall increasing diversity with decreasing temperature and fluid input. Slates showed highest diversity compared to the organic substrata. Temperature and fluid input had a significant influence on copepod community composition, resulting in higher similarity among stations with relatively high and low fluid inputs, respectively. While vent-specialists such as dirivultids and the tegastid Smacigastes micheli dominated substrata at high vent activity, the experiment demonstrated increasing abundance and dominance of non-vent taxa with decreasing temperature and fluid input. Effects of the substratum type on community composition were not significant, although at sites with moderate or low fluid input, woods exhibited distinctive communities with high densities and relative abundance of the taxon Nitocrella sp.. In conclusion, copepod colonization and species composition were mainly influenced by hydrothermal fluid input and temperature rather than the type of substratum. The outcome of this study provides fundamental knowledge to better understand copepod colonization at hydrothermal vent

Dispersion of deep-sea hydrothermal vent effluents and larvae by submesoscale and tidal currents

Deep-sea hydrothermal vents provide sources of geochemical materials that impact the global ocean heat and chemical budgets, and support complex biological communities. Vent effluents and larvae are dispersed and transported long distances by deep ocean currents, but these currents are largely undersampled and little is known about their variability. Submesoscale (0.1–10 km) currents are known to play an important role for the dispersion of biogeochemical materials in the ocean surface layer, but their impact for the dispersion in the deep ocean is unknown. Here, we use a series of nested regional oceanic numerical simulations with increasing resolution (from View the MathML sourceδx=6km to View the MathML sourceδx=0.75km) to investigate the structure and variability of highly-resolved deep currents over the Mid-Atlantic Ridge (MAR) and their role on the dispersion of the Lucky Strike hydrothermal vent effluents and larvae. We shed light on a submesoscale regime of oceanic turbulence over the MAR at 1500 m depth, contrasting with open-ocean – i.e., far from topographic features – regimes of turbulence, dominated by mesoscales.Impacts of submesoscale and tidal currents on larval dispersion and connectivity among vent populations are investigated by releasing neutrally buoyant Lagrangian particles at the Lucky Strike hydrothermal vent. Although the absolute dispersion is overall not sensitive to the model resolution, submesoscale currents are found to significantly increase both the horizontal and vertical relative dispersion of particles at O(1-10) km and O(1-10) days, resulting in an increased mixing of the cloud of particles. A fraction of particles are trapped in submesoscale coherent vortices, which enable transport over long time and distances. Tidal currents and internal tides do not significantly impact the horizontal relative dispersion. However, they roughly double the vertical dispersion. Specifically, particles undergo strong tidally-induced mixing close to rough topographic features, which allows them to rise up in the water column and to cross topographic obstacles.The mesoscale variability controls at first order the connectivity between hydrothermal sites and we do not have long enough simulations to conclude on the connectivity between the different MAR hydrothermal sites. However, our simulations suggest that the connectivity might be increased by submesoscale and tidal currents, which act to spread the cloud of particles and help them cross topographic barriers

Dispersion of deep-sea hydrothermal vent effluents and larvae by submesoscale and tidal currents

Deep-sea hydrothermal vents provide sources of geochemical materials that impact the global ocean heat and chemical budgets, and support complex biological communities. Vent effluents and larvae are dispersed and transported long distances by deep ocean currents, but these currents are largely undersampled and little is known about their variability. Submesoscale (0.1–10 km) currents are known to play an important role for the dispersion of biogeochemical materials in the ocean surface layer, but their impact for the dispersion in the deep ocean is unknown. Here, we use a series of nested regional oceanic numerical simulations with increasing resolution (from δx=6km to δx=0.75km) to investigate the structure and variability of highly-resolved deep currents over the Mid-Atlantic Ridge (MAR) and their role on the dispersion of the Lucky Strike hydrothermal vent effluents and larvae. We shed light on a submesoscale regime of oceanic turbulence over the MAR at 1500 m depth, contrasting with open-ocean – i.e., far from topographic features – regimes of turbulence, dominated by mesoscales. Impacts of submesoscale and tidal currents on larval dispersion and connectivity among vent populations are investigated by releasing neutrally buoyant Lagrangian particles at the Lucky Strike hydrothermal vent. Although the absolute dispersion is overall not sensitive to the model resolution, submesoscale currents are found to significantly increase both the horizontal and vertical relative dispersion of particles at O(1-10) km and O(1-10) days, resulting in an increased mixing of the cloud of particles. A fraction of particles are trapped in submesoscale coherent vortices, which enable transport over long time and distances. Tidal currents and internal tides do not significantly impact the horizontal relative dispersion. However, they roughly double the vertical dispersion. Specifically, particles undergo strong tidally-induced mixing close to rough topographic features, which allows them to rise up in the water column and to cross topographic obstacles. The mesoscale variability controls at first order the connectivity between hydrothermal sites and we do not have long enough simulations to conclude on the connectivity between the different MAR hydrothermal sites. However, our simulations suggest that the connectivity might be increased by submesoscale and tidal currents, which act to spread the cloud of particles and help them cross topographic barriers

Swimming speeds of polychaete larvae collected near deep-sea hydrothermal vents

http://www.godac.jamstec.go.jp/darwin/cruise/yokosuka/yk10-11/