Long-term diatom fluxes in response to oceanographic conditions at Stations AB and SA in the central subarctic Pacific and the Bering Sea, 1990–1998

Onodera, Jonaotaro; Takahashi, Kozo

doi:10.1016/j.dsr.2008.08.006

Cited by 27 publications

(13 citation statements)

References 44 publications

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“…It is apparent that the diatom taxon C. marginatus requires a relatively high nutrient supply and tolerates low light intensity. This is substantiated by the fact that (1) today this diatom taxon dwells in the lower euphotic zone off Spain (Nogueira et al, 2000;Nogueira and Figueiras, 2005), and (2) it occurs during early winter (November-January) in the subarctic Pacific and the Bering Sea based on time-series sediment trapping (Takahashi, 1986;Takahashi et al, 1989;Onodera and Takahashi, 2009). This timing of 2.8-2.6 Ma coincides approximately with the so-called end of "opal dump" observed in the subarctic Pacific at ~2.7 Ma, which is coincidental with the onset of NHG (Maslin et al, 1996).…”

Section: Changes In Biological Productivity and Subarctic Pacific Watmentioning

confidence: 90%

IODP Expedition 323Pliocene and Pleistocene Paleoceanographic Changes in the Bering Sea

Takahashi

Ravelo

Zarikian

2011

Scientific Drilling

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High-resolution paleoceanography of the Plio-Pleistocene is important in understanding climate forcing mechanisms and the associated environmental changes. This is particularly true in high-latitude marginal seas such as the Bering Sea, which has been very sensitive to changes in global climate during interglacial and glacial or Milankovitch time scales. This is due to significant changes in water circulation, land-ocean interaction, and sea-ice formation. With the aim to reveal the climate and oceanographic history of the Bering Sea over the past 5 Ma, Integrated Ocean Drilling Program (IODP) Expedition 323 cored a total of 5741 meters of sediment (97.4% recovery) at seven sites covering three different areas: Umnak Plateau, Bowers Ridge, and the Bering slope region. Four deep holes range from 600 m to 745 m spanning in age from 1.9 Ma to 5 Ma. The water depths (819 m to 3173 m) allow characterization of past vertical water mass distribution such as the oxygen minimum zone (OMZ). The results highlight three key points. (1) The first is an understanding of long-term evolution of surface-water mass distribution during the past 5 Ma including past sea-ice distribution and warm and less eutrophic subarctic Pacific water mass entry into the Bering Sea. (2) We characterized relatively stagnant intermediate water mass distribution imprinted as laminated sediment intervals that have been ubiquitously encountered. Today, the OMZ impinges upon the sediments at ~700-1600 m water depths. In the past, the OMZ appears to have occurred mainly during interglacial periods. Changes in low oxygen-tolerant benthic foraminiferal faunas clearly concur with this observation. (3) We also characterized significant changes between glacial episode of terrigenous sedimentary supply and interglacial episode of diatom flux.

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Section: Changes In Biological Productivity and Subarctic Pacific Watmentioning

confidence: 90%

IODP Expedition 323Pliocene and Pleistocene Paleoceanographic Changes in the Bering Sea

Takahashi

Ravelo

Zarikian

2011

Scientific Drilling

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“…Indeed, the highest dissolved silica concentration in the world (240 lmol/l) was measured in Bering Sea bottom water (Edmond et al, 1979;Tsunogai et al, 1979), and the Bering Sea is one of the most biologically productive areas in the world (Sambrotto et al, 1984). In contrast, the water of Station SA is less productive and the opal flux at this station is about half that of Station AB (Takahashi et al, 2000(Takahashi et al, , 2002Asahi and Takahashi, 2007;Onodera and Takahashi, 2009).…”

Section: Settling-particle Samplingmentioning

confidence: 99%

Composition of rare earth elements in settling particles collected in the highly productive North Pacific Ocean and Bering Sea: Implications for siliceous-matter dissolution kinetics and formation of two REE-enriched phases

Akagi

Hongo

et al. 2011

Geochimica et Cosmochimica Acta

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Settling particles were sampled monthly for 1 year using an automated time-series sediment trap positioned at similar depths at two sites of high diatomaceous productivity in the North Pacific Ocean and Bering Sea. The particles were analyzed for rare earth elements (REEs) by inductively coupled plasma mass spectrometry (ICP-MS) with and without chemical treatment of the bulk samples to isolate siliceous fractions. The REE composition of the bulk samples is explained largely by the contribution of two distinct components: (i) carbonate with a higher REE concentration, a negative Ce anomaly and lighter REE (LREE) enrichment; (ii) opal with a lower REE concentration, a weaker negative Ce anomaly and heavier REE (HREE) enrichment.The siliceous fractions of settling particles are characterized by high Si/Al ratios , reflecting high diatom productivity at the studied sites. The La/Al ratio of the siliceous fraction is close to that of the upper crust, but the Lu/Al and Lu/La ratios are significantly higher than those of the upper crust or airborne particles, indicating the presence of excess HREEs in the siliceous fraction. Diatoms are believed to be important carriers of HREEs.The Ce anomaly, Eu anomaly, slope of the REE pattern, and RREE of the siliceous fraction vary exponentially with decreasing total mass flux. They can be well-reproduced according to the differential dissolution kinetics of elements in the order of Ce < lighter REEs (LREEs) < Eu = heavier REEs (HREEs) < Si from settling particles, where the dissolution rate is critically reduced through particle aggregation. This order is consistent with the vertical distribution of dissolved REEs and Si in oceans. The differential dissolution kinetics leads to HREE enrichment of the original diatoms and REE enrichment of dissolved diatoms. The Lu/Si ratio of the siliceous fraction of settling particles recovered from some of the highest diatom fluxes is identical to that of the two elements dissolved in deep seawater, providing further evidence for the dissolution of siliceous matter in deep water.

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“…The second most abundant species were Actinocyclus curvatulus and Actinocyclus gallicus. Actinocyclus curvatulus is a planktonic neritic species often observed in nutrient-rich marine waters (ONODERA;TAKAHASHI, 2008) and which has been widely recorded in the Río de la Plata (FRENGUELLI, 1941;MÜLLER-MELCHERS, 1953). In our case it was equally observed in Montevideo Bay and the adjacent coastal zone.…”

Section: Discussionmentioning

confidence: 99%

Diatoms, protein and carbohydrate sediment content as proxies for coastal eutrophication in Montevideo, Rio de la Plata Estuary, Uruguay

et al. 2011

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A study on sediment surface diatom composition in relation to both protein/carbohydrate content and salinity was carried out in Montevideo Bay and the adjacent coastal zone. Samples were seasonally taken during one year along a human impact gradient, and the trophic conditions were assessed from the biochemical composition of the surface sediment organic matter. The co-occurrence of the marine-brackish (Actinocyclus curvatulus, Actinocyclus gallicus, Coscinodiscus excentricus, Coscinodiscus radiatus, Hyalodiscus subtilis, Paralia sulcata) and freshwater diatom flora (Aulacoseira granulata, Aulacoseira italica, Aulacoseira muzzanensis, Actinocyclus normanii, Amphora copulata, Cyclotella meneghiniana, Nitzschia linearis), suggests myxohaline estuarine conditions in the study area. The sampling stations located within the bay, close to several contamination sources, exhibited hypertrophic conditions as indicated by the highest levels of protein content, but also by the high relative abundances of Actinocyclus normanii and Cyclotella meneghiniana, as both diatom species are very well established cosmopolitan proxies of aquatic degradation. The levels of both protein and carbohydrate content, but also photosynthetic pigments, recorded in the adjacent coastal zone suggest meso-eutrophic conditions as contamination levels from the inner bay might become diluted off shore. Multivariate diatom species-environmental data relationships, indicate that the trophic gradient is hierarchically more important than salinity in explaining the diatom distribution. The present data imply an improvement in our ability of assessing organic contamination in the study area, since both biological and biopolymer variables were introduced for the first time as a tool for assessing the benthic health/degradation in one of the most populated regions of the Río de la Plata. RESUMOFoi realizado um estudo da salinidade e da composição das diatomáceas presentes no sedimento superficial em relação ao conteúdo de proteínas/carboidratos na Baía de Montevidéu e região costeira adjacente. Foram obtidas amostras sazonalmente durante um ano ao longo de um gradiente de impacto ambiental humano, e as condições tróficas foram determinadas através da análise da composição bioquímica da matéria orgânica do sedimento superficial. A coocorrência de espécies de diatomáceas marinhas-salobras, (Actinocyclus curvatulus, Actinocyclus gallicus, Coscinodiscus excentricus, Coscinodiscus radiatus, Hyalodiscus subtilis, Paralia sulcata) e diatomáceas indicadoras de águas doces (Aulacoseira granulata, Aulacoseira italica, Aulacoseira muzzanensis, Actinocyclus normanii, Amphora copulata, Cyclotella meneghiniana, Nitzschia linearis) sugerem condições mixohalinas estuarinas na área de estudo. As estações amostradas dentro da baía, próximas às fontes contaminadoras, apresentam condições hipertróficas apontadas pelos maiores valores de proteínas e pela alta abundância relativa de Actinocyclus normanii e Cyclotella meneghiniana, sendo que ambas espécies são considerad...

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Long-term diatom fluxes in response to oceanographic conditions at Stations AB and SA in the central subarctic Pacific and the Bering Sea, 1990–1998

Cited by 27 publications

References 44 publications

IODP Expedition 323Pliocene and Pleistocene Paleoceanographic Changes in the Bering Sea

IODP Expedition 323Pliocene and Pleistocene Paleoceanographic Changes in the Bering Sea

Composition of rare earth elements in settling particles collected in the highly productive North Pacific Ocean and Bering Sea: Implications for siliceous-matter dissolution kinetics and formation of two REE-enriched phases

Diatoms, protein and carbohydrate sediment content as proxies for coastal eutrophication in Montevideo, Rio de la Plata Estuary, Uruguay

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Long-term diatom fluxes in response to oceanographic conditions at Stations AB and SA in the central subarctic Pacific and the Bering Sea, 1990–1998

Cited by 27 publications

References 44 publications

IODP Expedition 323Pliocene and Pleistocene Paleoceanographic Changes in the Bering Sea

IODP Expedition 323Pliocene and Pleistocene Paleoceanographic Changes in the Bering Sea

Composition of rare earth elements in settling particles collected in the highly productive North Pacific Ocean and Bering Sea: Implications for siliceous-matter dissolution kinetics and formation of two REE-enriched phases

Diatoms, protein and carbohydrate sediment content as proxies for coastal eutrophication in Montevideo, Rio de la Plata Estuary, Uruguay

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Product

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IODP Expedition 323Pliocene and Pleistocene Paleoceanographic Changes in the Bering Sea

IODP Expedition 323Pliocene and Pleistocene Paleoceanographic Changes in the Bering Sea