MAR-ECO (Mid Atlantic Ridge ECOsystems, www.mar-eco.no),a pilot project of the Census of Marine Life (CoML, www.coml.org) had been implemented to study the pelagic ecosystems associated with the Mid-Atlantic Ridge (MAR) from Iceland to the Azores and to understand the structure and function of mid-ocean ridge communities. During several oceanographic expeditions nekton distribution, diversity, and species associations were observed, sampled and mapped along and across the northern MAR.

Besides zooplankton and fish, cephalopods were a major faunal group that characterized the ridge communities. During an oceanographic expedition with the Norwegian RV G.O. Sars in 2004 more than 1,200 specimens belonging to ca. 44 species and 25 families were sampled and identified from net catches ranging down to 3,000 m depth, many of them for the first time in this region (Vecchione et al., 2010a,b). The squid Gonatus steenstrupi, an important prey for marine top predators was the most abundant cephalopod, but some new species could also be described, with the deep-water squid Promachoteuthis sloani being a very prominent form (Young et al., 2006). The cephalopod species diversity increased from north to south. The present study, while extensive, has only been a summer-season snapshot. We have yet to discover the extent of seasonal changes either in species composition or in the occurrence of any species we found at the MAR.

Pelagic regions of the subtropical Atlantic Ocean are often regarded as „deserts“, because they are characterised by low primary productivity and low standing stocks of zooplankton and nekton. However, prominent current systems, seamounts and islands may create productive environments in these areas, in which cephalopods aggregate, feed and recruit.

Their early life stages can occur in exceptionally high densities and their distribution is often closely related to hydrographic conditions. In our ongoing research we examine comprehensive collections of oceanic cephalopods sampled near seamounts, but also in oceanic regions of the subtropical Atlantic Ocean. The epi- and mesopelagic early life cephalopods are a major focus of our studies. We document their distribution patterns, compile identification keys, and illustrate the various early life stages of the cephalopod species.

Considering the influence of environmental change on the Southern Ocean ecosystems and the services they provide, it is crucial to establish comprehensive baseline information on the Antarctic marine biodiversity, as a sound benchmark against which future changes can reliably be assessed (DeBroyer et al., 2011). Cephalopods are one of the most charismatic faunal groups in the Southern Ocean with less than 50 species of squids and octopods (Piatkowski, 2009). Of the ca. 20 squid species which regularly appear south of the Antarctic Polar Front, only two of them are endemic: the Antarctic neo-squid Alluroteuthis antarcticus and the glacial squid Psychroteuthis glacialis; but all of the squids are of pivotal importance in the high-Antarctic food web. Particularly, studies on the ecology and distribution of P. glacialis are of importance in our working group, because this species seems to be the only squid that inhabits the most southern waters like the Weddell Sea where it is supposed to prey on krill and myctophids (lanternfish) and where it forms the major prey of emperor penguins and seals (Piatkowski, 2011).

Information on Antarctic octopod species and their diversity has grown substantially during the last years. We described twelve new octopod species from bottom trawl samples taken during several expeditions with the RV Polarstern in the vicinity of the Antarctic Peninsula (e.g. Allcock et al. 2007; Vecchione et al. 2009a) (see species images below). The samples illustrate a higher than expected octopod species diversity and supply new information on their distribution patterns and ecological aspects. Furthermore, the trawl samples show that octopus populations have gained significantly higher abundances around the Antarctic Peninsula than in areas nearby. We speculate that this elevated abundance occurred after the rapid depletion of demersal fish stocks and may indicate a possible shift in the structure of the ecosystem (Vecchione et al. 2009b).