Respiration rates of tropical Atlantic copepods from the Cape Verde Islands

Copepods were sampled at two sampling sites off the island of São Vicente, Cape Verde Archipelago, in spring (March/April) and early summer (May/June) of 2010. The two sampling sites were located in Mindelo Bay (16.90N, 25.01W; bottom depth 22 m) and around 8 km off the town of São Pedro (16.77N, 25.12W; bottom depth 800 m). Samples were collected on board the local fishing vessel 'Sinagoga' using a WP-2 net (Hydrobios, 0.26 m**2 mouth opening, 200 µm mesh size). The net was either applied as a driftnet, drifting for 10 min in 22 to 0 m depth below the surface, or it was towed vertically with a towing speed of 0.5 m/s**1. For stratified sampling, the net was deployed in repetitive hauls from 560 to 210 m, from 210 to 80 m, and from 80 to 0 m in March/April and from 600 to 300 m, 300 to 100 m, and 100 to 0 m in May/June. Additional depth-integrated hauls were conducted from 600-0 m or 500-0 m during both field campaigns. Respiration rates of epi- and mesopelagic calanoid copepods were measured in the land-based laboratory at the Instituto Nacional de Desenvolvimento das Pescas (INDP) in Mindelo. Oxygen consumption was measured non-invasively by optode respirometry at three different ambient temperatures (13, 18, and 23°C) with a 10-channel oxygen respirometer (Oxy-10 Mini, PreSens Precision Sensing GmbH, Regensburg, Germany). All experiments were run in darkness in temperature-controlled incubators (LMS Cooled Incubator Series 1A, Model 280) equipped with water baths to ensure constant temperatures throughout the experiments, tolerating a variation of ±1°C.

Paleoenvironmental changes in the western Mediterranean since the last glacial maximum: High resolution multiproxy record from the Algero-Balearic basin

The present study uses a multiproxy approach in order to further understand the evolution of climate responses in the western Mediterranean as of the Last Glacial Maximum. Sediments from ODP Site 975 in the Algero-Balearic basin have been analysed at high resolution, both geochemically andmineralogicallly. The resulting data have been used as proxies to establish a sedimentary regime, primary marine productivity, the preservation of the proxies and oxygen conditions. Fluctuations in detrital element concentrations were mainly the consequence of wet/arid oscillations. Productivity has been established using Ba excess, according to which marine productivity appears to have been greatest during cold events Heinrich 1 and Younger Dryas. The S1 time interval was not as marked by increases in productivity as was the eastern Mediterranean. In contrast, the S1 interval was first characterized by a decreasing trend and then by a fall in productivity after the 8.2 ky BP dry-cold event. Since then productivity has remained low. Here we report that there was an important redox event in this basin, probably a consequence of the major oceanographic circulation change occurring in the western Mediterranean at 7.7 ky BP. This circulation change led to reventilation as well as to diagenetic remobilization of redox-sensitive elements and organic matter oxidation. Comparisons between our paleoceanographic reconstruction for this basin and those regarding other Mediterranean basins support the hypothesis that across the Mediterranean there were different types of responses to climate forcing mechanism. The Algero-Balearic basin is likely to be a key area for further understanding of the relationships between the North Atlantic and the eastern Mediterranean basins.

Sedimentological investigations of a sediment core profile from the continental slope of the South Orkney Islands

Sediment patterns such as texture, composition, and facies from three selected areas of the Antarctic continental margin of the Weddell Sea are discussed in relation to environmental variations of the Quaternary hydrosphere and kryosphere. Advance and retreat of ice shelves as well as oscillations in sea ice coverage are reflected by particular sediment facies. The distribution of ice-rafted detritus tracks the Antarctic Coastal Current, and the Weddell Sea Bottom water contour current can be recognized by its distinctive winnowing and erosion pattern. Distribution and abundance of biogenic sediment components are mainly controlled by duration of sea ice coverage reflecting the long-term climatic evolution.

A multiproxy analysis of late MIS 6 to early MIS 5d OSP Site 161-975 sediments

A multiproxy analysis based on planktic foraminiferal abundances, derived SSTs, and stable planktic isotopes measurements together with alkenone abundances and Uk'37 SSTs was performed on late MIS 6 to early MIS 5d sediment recovered from Site 975 (ODP Leg 161) in the South Balearic Islands basin (Western Mediterranean) with emphasis on reconstructing the climate progression of the last interglacial period. A number of abrupt climate changes related to alternative influence of nutrient rich northern and oligotrophic southern water masses were revealed. Heinrich event 11 and cooling events C27, C26, C25, C24, C23, which have been previously described in the North Atlantic, were recognized. However, in comparison to the eastern North Atlantic mid-latitude region, events C27 and C26 at Site 975 seem to be significantly more pronounced. Together with evidence of a two-phase climate optimum with maximum SSTs reached during its later phase, this implies a close similarity in climate dynamics between the Western Mediterranean and the Nordic seas. We propose that postglacial effects in the Nordic seas had an influence on the western Mediterranean climate via atmospheric circulation and that these effects competed with the insolation force.