Environmental control on the structure of echinoid assemblages in the Bellingshausen Sea (Antarctica)

The Bellingshausen Sea is one of the most remote and least surveyed seas of the Southern Ocean, so that little was known about benthic communities and those factors that determine community structuring until recently. The present work aims at characterizing the structure and spatial distribution of echinoid assemblages in the Bellingshausen Sea, as well as identifying the environmental factors that determine assemblage structuring. Echinoids were collected at 32 stations using an Agassiz trawl, at depths of 86–3,304 m, during BENTART oceanographic expeditions led in 2003 and 2006. Sediment and bottom water properties were analysed using an USNEL-type box corer and a Neil Brown Instrument System Mark III CTD, respectively. Echinoids were found at all stations, except Peter I Island. Seventeen species were identified, representing 22 % of the echinoid species present in the Southern Ocean and increasing twofold the number of species recorded in the Bellingshausen Sea so far. The echinoid fauna is dominated by the very abundant species Sterechinus antarcticus. Depth is the key factor that determines the nature of echinoid assemblages, which are mainly divided into the continental shelf, the slope and the deep-sea basin. In addition, sediment properties, namely redox values, organic matter and mud content, best match species dispersion on the shelf. Sediment properties affect echinoid distribution depending on species food range and feeding strategy. As it might be expected, sediment properties more strongly influence specialist feeders (Schizasteridae and Cidaridae) than generalists (Echinidae).Versión del edito

Primate modularity and evolution: first anatomical network analysis of primate head and neck musculoskeletal system

Network theory is increasingly being used to study morphological modularity and integration. Anatomical network analysis (AnNA) is a framework for quantitatively characterizing the topological organization of anatomical structures and providing an operational way to compare structural integration and modularity. Here we apply AnNA for the first time to study the macroevolution of the musculoskeletal system of the head and neck in primates and their closest living relatives, paying special attention to the evolution of structures associated with facial and vocal communication. We show that well-defined left and right facial modules are plesiomorphic for primates, while anthropoids consistently have asymmetrical facial modules that include structures of both sides, a change likely related to the ability to display more complex, asymmetrical facial expressions. However, no clear trends in network organization were found regarding the evolution of structures related to speech. Remarkably, the increase in the number of head and neck muscles – and thus of musculoskeletal structures – in human evolution led to a decrease in network density and complexity in humans

BIOGEOGRAPHY AND MACROECOLOGY OF ANTARCTIC AND SUB-ANTARCTIC ECHINOIDS USING A GEOGRAPHIC INFORMATION SYSTEM.

participantMany features already show how Polar seas are impacted by present-day global warming. To cope with new climate-induced changes and survive, Antarctic and Subantarctic marine organisms can either migrate or adapt to new prevailing conditions. New biotic interactions between Southernmost species and Subantarctic invaders can be expected, as new biogeographical distributions have already been documented. Because they are biologically and ecologically well diversified, echinoids play an important part in Antarctic benthic communities. Moreover, symbioses associated to cidarid echinoids make them even more crucial for benthic diversity. The biogeographical mapping of Antarctic echinoids (south of latitude 35° S) is being performed using both data from literature and new records from the numerous recent cruise campaigns around Antarctica. The second step and objective of our work is to identify and characterize the main factors that control echinoid distribution in the Antarctic. To obtain a comprehensive model of echinoid biogeographical and macroecological patterns, physical data are matched to echinoid distribution using GIS. Two alternative hypotheses will be tested: (1) is Antarctic echinoid distribution controlled by environmental and physical factors such as water temperature, sediments and depth (the environmental hypothesis) or (2) is echinoid distribution best explained by historical biogeography (the provincialist hypothesis)

<strong>A field guide to coastal echinoderms of the Kerguelen Islands</strong>

International audienceOne of the current challenges in today's ecology research is to understand and quantify the effects of climate changes on biodiversity. In order to detect possible trends in biodiversity patterns, it is necessary to conduct long-term observations in various and representative environments. This is always challenging, even more difficult in marine habitats and in the Southern Ocean in particular. Since 2012, a submarine observatory of the coastal benthos has been in operation in the Kerguelen Islands. Eight contrasting sites are monitored using photo and video surveys, loggers, and settlement plots. To quantify potential changes, several photographic analysis techniques are also complemented by scuba diving and ROV (Remotely Operated Vehicle) observations. Investigator scientists have developed and improved new protocols that will be carried out in the long term by the staff of the National Natural Reserve of the French Southern Territories. In order to provide reliable support of species identification, the Proteker program supported by IPEV, French Polar Institute, is currently developing several field guides that should improve the identification of the main taxa being monitored. In light of their abundance in coastal environments of the Kerguelen Islands, and because they are among the most visible invertebrates and the easiest of organisms to consider for monitoring surveys, we first focused on echinoderms. Results of this first study are presented here. For each echinoderm species, a spreadsheet provides the species name with synonymies, a description of diagnostic features, the recorded distribution, as well as three different types of illustrations: (i) living specimens in their environment, which is useful for scuba divers, (ii) fresh collected specimens out of water, and (iii) specimens fixed in ethanol. Therefore, species can be identified alive while diving, but also after sampling in the field, and after several years in the laboratory. An assessment of Kerguelen's coastal echinoderms is also given