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| Fietz, Susanne; Martinez-garcia, Alfredo; Rueda, Gemma; Peck, Vicky L.; Huguet, Carme; Escala, Marina; Rosell-mele, Antoni. |
| The concentrations of chlorins (chlorophyll transformation products indicative of phytoplankton production) and crenarchaeol (a marker for Crenarchaea abundance) are significantly positively correlated (Spearman's rank correlation coefficient r(s) > 0.75) in four core records from freshwater (Lake Baikal) and marine settings (Southern, Atlantic, and Arctic Oceans). This suggests a close relationship between Crenarchaea abundance and phytoplankton production. Degradation and transport mechanisms, as well as a common environmental trigger, may in part account for our observations, but these mechanisms alone cannot fully explain them. Instead our findings point to a metabolic dependence of Crenarchaea on resources released by phytoplankton, such as organic... |
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| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00230/34121/32603.pdf |
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| Ho, Sze Ling; Mollenhauer, Gesine; Lamy, Frank; Martinez-garcia, Alfredo; Mohtadi, Mahyar; Gersonde, Rainer; Hebbeln, Dierk; Nunez-ricardo, Samuel; Rosell-mele, Antoni; Tiedemann, Ralf. |
| In spite of the important role played by the Southern Ocean in global climate, the few existing paleoceanographic records in the east Pacific sector do not extend beyond one glacial-interglacial cycle, hindering circumpolar comparison of past sea surface temperature (SST) evolution in the Southern Ocean. Here we present three alkenone-based Pleistocene SST records from the subantarctic and subtropical Pacific. We use a regional core top calibration data set to constrain the choice of calibrations for paleo SST estimation. Our core top data confirm that the alkenone-based U-37(K) and U-37(K') values correlate linearly with the SST, in a similar fashion as the most commonly used laboratory culture-based calibrations even at low temperatures (down to similar... |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00265/37610/36990.pdf |
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| Mcclymont, Erin L.; Sosdian, Sindia M.; Rosell-mele, Antoni; Rosenthal, Yair. |
| mid-Pleistocene climate transition (MPT) is defined by the emergence of high amplitude, quasi-100 ka glacial-interglacial cycles from a prior regime of more subtle 41 ka cycles. This change in periodicity and amplitude cannot be explained by a change in 'external' astronomical forcing. Here, we review and integrate published records of sea-surface temperatures (SSTs) to assess whether a common global expression of the MPT in the surface ocean can be recognized, and examine our findings in light of mechanisms proposed to explain climate system reorganization across the MPT. We show that glacial-interglacial variability in SSTs is superimposed upon a longer-term cooling trend in oceanographic systems spanning the low-to high-latitudes. Regional variability... |
| Tipo: Text |
Palavras-chave: Sea surface temperatures; Mid-Pleistocene transition; Ice sheets; 100 kyr world. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37510/82770.pdf |
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