Nematode abundance of the Eastern Mediterranean Sea in cold seep sediments collected during the MEDECO2 cruise (2007)

Sediment was collected by either push cores operated by the ROV Quest or by a television guided Multicorer. Nematodes abundance were calculated of the top 5 cm of the sediment to gain individual abundance per 10 cm**2.

Radiocarbon dating on cold-water corals and planktonic foraminifera, grain size analysis, stable oxygen isotopes, and XRF data of sediment cores from the Alboran Sea

Cold-water corals are common along the Moroccan continental margin off Melilla in the Alboran Sea (western Mediterranean Sea), where they colonise and largely cover mound and ridge structures. Radiocarbon ages of the reef-forming coral species Lophelia pertusa and Madrepora oculata sampled from those structures, reveal that they were prolific in this area during the last glacial-interglacial transition with pronounced growth periods covering the Bølling-Allerød interstadial (13.5-12.8 ka BP) and the Early Holocene (11.3-9.8 ka BP). Their proliferation during these periods is expressed in vertical accumulation rates for an individual coral ridge of 266-419 cm ka**-1 that consists of coral fragments embedded in a hemipelagic sediment matrix. Following a period of coral absence, as noted in the records, cold-water corals re-colonised the area during the Mid-Holocene (5.4 ka BP) and underwater photographs indicate that corals currently thrive there. It appears that periods of sustained cold-water coral growth in the Melilla Coral Province were closely linked to phases of high marine productivity. The increased productivity was related to the deglacial formation of the most recent organic rich layer in the western Mediterranean Sea and to the development of modern circulation patterns in the Alboran Sea.

Nematode abundance in cold seep sediments of the Nordic Margins (Nyregga, Styregga, Haakon Mosby Mud Volcano)

Cold-seep environments and their associated symbiont-bearing mega faunal communities create islands of primary production for macro-and meiofauna in the otherwise monotonous and nutrient-poor deep-sea environment. To examine the spatial variation and distribution patterns of metazoan meiobenthos in different seepage-related habitats, samples were collected in two regions off Norway: several pockmarks associated with the Storegga Slide including the Nyegga pockmark area, and the active, methane-venting Haakon Mosby Mud Volcano west of the Barents Sea during the Vicking cruise aboard the RV ''PourquoiPas?'' in May-June 2006. Meiofaunal samples at control sites were sampled with a multiple corer, while the other sites were sampled with push cores operated by the ROV Victor6000.The meiofaunal samples were fixed in 4% buffered formaldehyde and washed over a 32 mm-mesh sieve. Metazoan meiofauna were extracted by density gradient centrifugation. All material was fixed with 4% buffered formalin and stained with Rose Bengal. The metazoan meiofauna was sorted out, enumerated and identified down to major taxa under the stereomicroscope. Afterwards, abundances of Nematodes were depth integrated over the top 5 cm to gain individual abundances per 10 cm**2.

Seawater carbonate chemistry, nutrients and calcification during experiments with cold-water scleractinian corals (Lophelia pertusa, Madrepora oculata and Desmophyllum dianthus), 2011

Global environmental changes, including ocean acidification, have been identified as a major threat to scleractinian corals. General predictions are that ocean acidification will be detrimental to reef growth and that 40 to more than 80 per cent of present-day reefs will decline during the next 50 years. Cold-water corals (CWCs) are thought to be strongly affected by changes in ocean acidification owing to their distribution in deep and/or cold waters, which naturally exhibit a CaCO3 saturation state lower than in shallow/warm waters. Calcification was measured in three species of Mediterranean cold-water scleractinian corals (Lophelia pertusa, Madrepora oculata and Desmophyllum dianthus) on-board research vessels and soon after collection. Incubations were performed in ambient sea water. The species M. oculata was additionally incubated in sea water reduced or enriched in CO2. At ambient conditions, calcification rates ranged between -0.01 and 0.23% d-1. Calcification rates of M. oculata under variable partial pressure of CO2 (pCO2) were the same for ambient and elevated pCO2 (404 and 867 µatm) with 0.06 ± 0.06% d-1, while calcification was 0.12 ± 0.06% d-1 when pCO2 was reduced to its pre-industrial level (285 µatm). This suggests that present-day CWC calcification in the Mediterranean Sea has already drastically declined (by 50%) as a consequence of anthropogenic-induced ocean acidification.