There is growing scientific evidence that, as a result of increasing anthropogenic carbon dioxide... more There is growing scientific evidence that, as a result of increasing anthropogenic carbon dioxide (CO2) emissions, absorption of CO2 by the oceans has already noticeably increased the average oceanic acidity from pre-industrial levels. This global threat requires a global response. According to the Intergovernmental Panel on Climate Change (IPCC), continuing CO2 emissions in line with current trends could make the oceans up to 150% more acidic by 2100 than they were at the beginning of the Anthropocene. Acidification ...
There is growing scientific evidence that, as a result of increasing anthropogenic carbon dioxide... more There is growing scientific evidence that, as a result of increasing anthropogenic carbon dioxide (CO2) emissions, absorption of CO2 by the oceans has already noticeably increased the average oceanic acidity from pre-industrial levels. This global threat requires a global response. According to the Intergovernmental Panel on Climate Change (IPCC), continuing CO2 emissions in line with current trends could make the oceans up to 150% more acidic by 2100 than they were at the beginning of the Anthropocene. Acidification ...
The chemistry of coccoliths serves both as a record of changes in the chemistry of the ocean and ... more The chemistry of coccoliths serves both as a record of changes in the chemistry of the ocean and as a record of environmental and biological conditions like temperature and productivity. It documents different information than that of foraminiferal carbonate because coccolithophorids, unlike foraminifers, are primary producers. Recently, a breakthrough in the separation of monospecific coccolith assemblages enabled detailed work on stable isotope composition and minor and trace elements of individual coccolith species in sediment trap and sediment samples. Culture studies indicate different nonequilibrium effects in the oxygen isotope fractionations in different species of coccolithophorids. Interest in nonequilibrium effects is also increasing as new studies reveal that these effects may provide useful new indicators for paleoceanographic studies. In the case of coccolithophorids, nonequilibrium effects appear to reflect changing ecological and physiological responses of the organi...
Off South Africa, surface and intermediate waters flow from the Indian- to the Atlantic Ocean in ... more Off South Africa, surface and intermediate waters flow from the Indian- to the Atlantic Ocean in the form of Agulhas rings and/or as direct Agulhas leakage. The inter-ocean exchange of water plays a crucial role in the global thermohaline circulation due to the contribution of heat and salt from the Indian to the South Atlantic Ocean. We use the shells of different species of planktic foraminfera to reconstruct the late Pleistocene paleoceanography and the history of inter-ocean exchange off South Africa. Our geological archive from the Cape Basin, is located on the continental slope southwest off Cape Town, exactly underneath the pathway of Agulhas rings and direct Agulhas leakage. Observations on living planktic foraminifera, collected with depth stratified plankton tows in this area (years 2000 - 2001), show that Agulhas ring waters are characterised by a distinct faunal composition. Based on these observations we are able to select those species that are strictly associated to w...
ABSTRACT The stable isotope compositions of the planktonic foraminifera Globigerina bulloides, Gl... more ABSTRACT The stable isotope compositions of the planktonic foraminifera Globigerina bulloides, Globigerinoides ruber (white and pink varieties), Globigerinoides trilobus, Globorotalia inflata and Globorotalia truncatulinoides (right- and left-coiling types) were examined as recorders of North Atlantic surface water properties based on 40 box-core surface sediments between 60°and 30°N. While G. ruber (white and pink varieties) and G. trilobus mainly reflect summer surface water conditions in their oxygen isotope composition, G. bulloides reflects temperatures of the northward-migrating spring bloom, February-March in the south to May-June in the north. Our data show that G. bulloides cannot be regarded as an indicator for summer temperatures as deduced from Duplessy et al.'s data. Gt. inflata and Gt. truncatulinoides (right- and left-coiling) build their shells in the coldest waters compared with the other species and reflect temperatures between 100 and 400 m water depth. The difference in oxygen isotope composition between G. bulloides and G. inflata serves as a proxy for water mass stratification. G. bulloides is the only species that gives a distinct pattern in its carbon isotopic composition showing a high correlation with the surface water phosphate values along the transect and may serve as a proxy for palaeonutrients and/or productivity.
There is growing scientific evidence that, as a result of increasing anthropogenic carbon dioxide... more There is growing scientific evidence that, as a result of increasing anthropogenic carbon dioxide (CO2) emissions, absorption of CO2 by the oceans has already noticeably increased the average oceanic acidity from pre-industrial levels. This global threat requires a global response. According to the Intergovernmental Panel on Climate Change (IPCC), continuing CO2 emissions in line with current trends could make the oceans up to 150% more acidic by 2100 than they were at the beginning of the Anthropocene. Acidification ...
There is growing scientific evidence that, as a result of increasing anthropogenic carbon dioxide... more There is growing scientific evidence that, as a result of increasing anthropogenic carbon dioxide (CO2) emissions, absorption of CO2 by the oceans has already noticeably increased the average oceanic acidity from pre-industrial levels. This global threat requires a global response. According to the Intergovernmental Panel on Climate Change (IPCC), continuing CO2 emissions in line with current trends could make the oceans up to 150% more acidic by 2100 than they were at the beginning of the Anthropocene. Acidification ...
The chemistry of coccoliths serves both as a record of changes in the chemistry of the ocean and ... more The chemistry of coccoliths serves both as a record of changes in the chemistry of the ocean and as a record of environmental and biological conditions like temperature and productivity. It documents different information than that of foraminiferal carbonate because coccolithophorids, unlike foraminifers, are primary producers. Recently, a breakthrough in the separation of monospecific coccolith assemblages enabled detailed work on stable isotope composition and minor and trace elements of individual coccolith species in sediment trap and sediment samples. Culture studies indicate different nonequilibrium effects in the oxygen isotope fractionations in different species of coccolithophorids. Interest in nonequilibrium effects is also increasing as new studies reveal that these effects may provide useful new indicators for paleoceanographic studies. In the case of coccolithophorids, nonequilibrium effects appear to reflect changing ecological and physiological responses of the organi...
Off South Africa, surface and intermediate waters flow from the Indian- to the Atlantic Ocean in ... more Off South Africa, surface and intermediate waters flow from the Indian- to the Atlantic Ocean in the form of Agulhas rings and/or as direct Agulhas leakage. The inter-ocean exchange of water plays a crucial role in the global thermohaline circulation due to the contribution of heat and salt from the Indian to the South Atlantic Ocean. We use the shells of different species of planktic foraminfera to reconstruct the late Pleistocene paleoceanography and the history of inter-ocean exchange off South Africa. Our geological archive from the Cape Basin, is located on the continental slope southwest off Cape Town, exactly underneath the pathway of Agulhas rings and direct Agulhas leakage. Observations on living planktic foraminifera, collected with depth stratified plankton tows in this area (years 2000 - 2001), show that Agulhas ring waters are characterised by a distinct faunal composition. Based on these observations we are able to select those species that are strictly associated to w...
ABSTRACT The stable isotope compositions of the planktonic foraminifera Globigerina bulloides, Gl... more ABSTRACT The stable isotope compositions of the planktonic foraminifera Globigerina bulloides, Globigerinoides ruber (white and pink varieties), Globigerinoides trilobus, Globorotalia inflata and Globorotalia truncatulinoides (right- and left-coiling types) were examined as recorders of North Atlantic surface water properties based on 40 box-core surface sediments between 60°and 30°N. While G. ruber (white and pink varieties) and G. trilobus mainly reflect summer surface water conditions in their oxygen isotope composition, G. bulloides reflects temperatures of the northward-migrating spring bloom, February-March in the south to May-June in the north. Our data show that G. bulloides cannot be regarded as an indicator for summer temperatures as deduced from Duplessy et al.'s data. Gt. inflata and Gt. truncatulinoides (right- and left-coiling) build their shells in the coldest waters compared with the other species and reflect temperatures between 100 and 400 m water depth. The difference in oxygen isotope composition between G. bulloides and G. inflata serves as a proxy for water mass stratification. G. bulloides is the only species that gives a distinct pattern in its carbon isotopic composition showing a high correlation with the surface water phosphate values along the transect and may serve as a proxy for palaeonutrients and/or productivity.
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