An expedition to Salas y Gómez and Easter islands was conducted to develop a comprehensive baseline of the nearshore marine ecosystem, to survey seamounts of the recently created Motu Motiro Hiva Marine Park (MMHMP) – a no‐take marine reserve of 150 000 km2 – and to compare these results with Easter Island where the marine ecosystem is similar but has no marine protection.Live coral cover was surprisingly high at both Easter Island (53%) and Salas y Gómez (44%), especially considering their sub‐tropical location, high wave energy environments, and geographic isolation.Endemic and regionally‐endemic species comprised 77% of the fish abundance at Easter Island and 73% at Salas y Gómez. Fish biomass at Salas y Gómez was relatively high (1.2 t ha‐1) and included a large proportion of apex predators (43%), whereas at Easter Island it was almost three times lower (0.45 t ha‐1) with large predators accounting for less than 2% of the biomass, despite good habitat quality.The large cohort of small sharks and the absence of larger sharks at Salas y Gómez suggest mesopredator release consistent with recent shark fishing. The fish fauna at the seamounts between Easter Island and Salas y Gómez, outside of MMHMP, harboured 46% endemic species, including a new species of damselfish (Chromis sp. nov.) and probably a new species of Chimaera (Hydrolagus). Numerous seamounts adjacent to Salas y Gómez are currently not included in the MMHMP.This expedition highlights the high biodiversity value of this remote part of the Pacific owing to the uniqueness (endemicity) of the fauna, large apex predator biomass, and geographic isolation.Copyright © 2013 John Wiley & Sons, Ltd.

Depth distribution data were compared for 172 European and 157 Antarctic benthic invertebrate species occurring in the respective shelf areas. Antarctic species showed significantly wider depth ranges in selected families of the groups Bivalvia, Gastropoda, Amphipoda and Decapoda. No differences were found in Polychaeta, Asteroidea and Ophiuroidea, where European species also showed comparatively wide bathymetric ranges. These extended levels of eurybathy in the Antarctic benthos may be interpreted either as an evolutionary adaptation or pre-adaptation to the oscillation of shelf ice extension during the Antarctic glacial-interglacial cycle.

SUMMARY:The biogeography and ecology of decapod crustaceans was described for the higher latitudes of the Southern Ocean. The analyzed area included the transitional or antiboreal region of the South American continental shelves (south of about 42°30'S), the Antarctic continental shelves, the Subantarctic islands of the Scotia and the Kerguelen Arcs, the deep sea south of about 42°S and the pelagic realm between the Subtropical Convergence and the Antarctic continent. A broad base of own data and a review of the literature revealed the presence of 98 benthic decapod species in the entire area, with 92 species on the continental shelves and around the Subantarctic islands, and 6 species in the deep sea. A total of 34 decapod species live in the pelagic system south of the Subtropical Convergence. About 50 % of the benthic species, nearly all deep-sea species, but only one pelagic decapod are endemic in the analyzed sectors of the Southern Ocean. Eualus kinzeri (Caridea: Hippolytidae) is the only endemic decapod of the Antarctic continental shelves. By means of a multivariate cluster analysis the antiboreal decapod fauna of South America was separated from the species living around Antarctica and the Subantarctic islands of the Scotia and Kerguelen Arc. In contrast to earlier studies the northern distribution limit of the Antarctic decapod fauna was set at approximately 55°30'S, and includes species which are distributed on the southern tip of South America. The species number in the antiboreal region of South America is 79, and higher than known before. The caridean shrimps are the most numerous group within the entire area, and together with the anomuran crabs, the palinuran and astacuran lobsters they demonstrate a high degree of eurybathy compared to the Brachyura. The restriction of the Brachyura to shallow-water zones is discussed as one reason, that caused the absence of this group on the Antarctic continental shelves after the successive elimination of the shallow-water fauna during glaciation of the southern hemisphere.Key words: Biogeography, decapod crustaceans, Southern Ocean.RESUMEN: LA BIOGEOGRAFÍA Y ECOLOGÍA DE LA FAUNA DE LOS CRUSTÁCEOS DECÁPODOS DEL OCÉANO AUSTRAL. -Se describe la biogeografía y ecología de crustáceos decápodos para altas latitudes del Océano Austral. El área analizada incluye la región antiboreal de las plataformas continentales sudamericanas (sur de 42º30'S), las plataformas continentales antárti-cas, las islas de los Archipiélagos de Escocia y Kerguelen, el mar profundo al sur cerca de los 42º y el reino pelágico entre la Convergencia Subtropical y el continente antártico. Una amplia base de datos, propios y bibliográficos, reveló la presencia de 98 especies de decápodos en el área; 92 de estas especies se encontraron sobre las plataformas continentales y alrededor de las islas subantárticas, mientras que 6 lo fueron en mar profundo. Un total de 34 especies de decápodos viven en el sistema pelágico al sur de la Convergencia Subtropical. Alrededor del 50% de las especies bentóni...

We try to design a simple model exhibiting self-organized criticality, which is amenable to a rigorous mathematical analysis. To this end, we modify the generalized Ising Curie-Weiss model by implementing an automatic control of the inverse temperature. With the help of exact computations, we show that, in the case of a centered Gaussian measure with positive variance σ 2 , the sum Sn of the random variables has fluctuations of order n 3/4 and that Sn/n 3/4 converges to the distribution C exp(−x 4 /(4σ 4 )) dx where C is a suitable positive constant.AMS 2010 subject classifications : 60F05 60K35.

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