Distribution of trace elements in benthic infralittoral organisms from the western Antarctic Peninsula reveals no latitudinal gradient of pollution

Antarctica is considered one of the most pristine regions on Earth, but evidences of global and local anthropogenic pollution exist. Chromium (Cr), lead (Pb) and mercury (Hg) are bioaccumulated and sometimes biomagnified through the trophic web. We aim to determine whether a latitudinal gradient of these trace elements exists in benthic organisms along the rocky shores of the Antarctic Peninsula and the South Shetland Islands. Levels of Cr, Pb, and Hg were measured by ICP-MS in two macroalgae (Palmaria decipiens and Desmarestia anceps or Desmarestia menziesii), one gastropod (Nacella concinna), two starfishes (Odontaster validus and Diplasterias brucei), and suspended particulate organic matter (SPOM) from five sampling sites ranging in latitude from 62°11′17″S to 67°33′47″S. Levels of trace elements differed among sites and species, but no latitudinal gradient was observed for these pollutants. Levels of Hg and Pb in animals were consistent with biomagnifications along the food web, as were higher is starfish than in limpets. However, macroalgae and SPOM are unlikely to be the main primary producers supporting those consumers, as Hg levels in macroalgae and Pb levels in SPOM were much higher than in animals. The levels of trace elements detected were similar or higher than in other Antarctic places and other regions of the world, thus indicating that the Antarctic Peninsula area is as polluted as the rest of the world.

The abundance and distribution of echinoderms in nearshore hard-bottom habitats near Anvers Island, western Antarctic Peninsula

Echinoderms are well represented in nearshore hard-bottom (< 100 m depth) habitats along the Antarctic Peninsula where they are presumably important contributors to benthic production, carbon flow, and determinants of community structure. The present study assesses the densities of echinoderms at shallow depths (2–15 m) at five sampling sites within three kilometres of Anvers Island on the central western Antarctic Peninsula. The asteroids Odontaster validus, Granaster nutrix, Lysasterias perrieri and Adelasterias papillosa, two ophiuroids in the Amphiuridae, the holothuroids Psolicrux coatsi and Psolus carolineae and one representative of the Cucumaridae, and the regular echinoid Sterechinus neumayeri were enumerated. Mean total echinoderm densities were high (34.9 individuals m-2) and ranged from 21.9 individuals m-2 for asteroids to 2.7 individuals m-2 for holothuroids. With the exception of a positive relationship between the abundance of the regular echinoid Sterechinus neumayeri and the biomass of the brown alga Himanthothallus grandifolius, no significant relationships were found between the abundance of asteroids, ophiuroids, or holothuroids and two species of brown algae or three algal ecotypes. The present study indicates nearshore hard-bottom echinoderms are important in the carbon cycle and their inherent vulnerability to ocean acidification may have community-level impacts.

The effects of temperature on the behaviour of the Antarctic sea star Odontaster validus

The effects of temperature on the behaviour of the Antarctic sea starOdontaster validusMany Antarctic marine benthic invertebrates are adapted to specific environmental conditions (e.g.low stable temperatures, high salinity and oxygen content). Changes caused by global climatic shifts can be expected to have significant impact on their physiology and distribution.Odontaster validus, an ubiquitous, omnivorous sea star is one of the "keystone species" in the Antarctic benthic communities. Laboratory experiments were carried out to study the effect of temperature rise (from 0 to 5°C) on some vital biological functions that sea stars must perform in order to survive in their environment. Parameters such as behavioural reaction of sea stars to food and food odour, locomotory performance and ability to right were measured. Temperature increase significantly impaired the ability ofO. validusto perform these functions (e.g.lowering the number of sea stars able to right, increasing time-to-right, reducing locomotory activity, weakening chemosensory reaction to food and food odour). At temperatures of 4 and 5°C a loss of motor coordination was observed, although at all tested temperatures up to 5°C there were single individuals performing successfully.