Selective preservation of upwelling-indicating diatoms in sediments off Somalia, NW Indian Ocean

Koning, Erica; Iperen, Jolanda Van; Raaphorst, Wim van; Helder, W.; Brummer, Geert-Jan A; Weering, Tjeerd C.E. van

doi:10.1016/s0967-0637(01)00019-x

Cited by 51 publications

(39 citation statements)

References 37 publications

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“…According to Demarest et al (2009), if the preservation efficiency between different diatom assemblages has a difference > 20 % from each other, then the δ 30 Si might change by ± 0.1 ‰, whereby this process increases linearly as dissolution progresses. As previously demonstrated, Chaetoceros shows a high resistance to dissolution (Koning et al, 2001), and T. antarctica builds mats which usually are also well protected against dissolution (Ragueneau et al, 2000). This feature explains why well-preserved diatoms are found in the BUS sediment during the Plio-Pleistocene climate transition (Lange et al, 1999).…”

Section: Silicon Isotope Compositions (δ 30 Si) Of Diatomssupporting

confidence: 52%

Contribution of changes in opal productivity and nutrient distribution in the coastal upwelling systems to Late Pliocene/Early Pleistocene climate cooling

et al. 2012

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Abstract. The global Late Pliocene/Early Pleistocene cooling (∼ 3.0-2.0 million years ago -Ma) concurred with extremely high diatom and biogenic opal production in most of the major coastal upwelling regions. This phenomenon was particularly pronounced in the Benguela upwelling system (BUS), off Namibia, where it is known as the Matuyama Diatom Maximum (MDM). Our study focuses on a new diatom silicon isotope (δ 30 Si) record covering the MDM in the BUS. Unexpectedly, the variations in δ 30 Si signal follow biogenic opal content, whereby the highest δ 30 Si values correspond to the highest biogenic opal content. We interpret the higher δ 30 Si values during the MDM as a result of a stronger degree of silicate utilisation in the surface waters caused by high productivity of mat-forming diatom species. This was most likely promoted by weak upwelling intensity dominating the BUS during the Late Pliocene/Early Pleistocene cooling combined with a large silicate supply derived from a strong Southern Ocean nutrient leakage responding to the expansion of Antarctic ice cover and the resulting stratification of the polar ocean 3.0-2.7 Ma ago. A similar scenario is hypothesized for other major coastal upwelling systems (e.g. off California) during this time interval, suggesting that the efficiency of the biological carbon pump was probably sufficiently enhanced in these regions during the MDM to have significantly increased the transport of atmospheric CO 2 to the deep ocean. In addition, the coeval extension of the area of surface water stratification in both the Southern Ocean and the North Pacific, which decreased CO 2 release to the atmosphere, led to further enhanced atmospheric CO 2 drawn-down and thus contributed significantly to Late Pliocene/Early Pleistocene cooling.

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Section: Silicon Isotope Compositions (δ 30 Si) Of Diatomssupporting

confidence: 52%

Contribution of changes in opal productivity and nutrient distribution in the coastal upwelling systems to Late Pliocene/Early Pleistocene climate cooling

et al. 2012

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“…It is well known that small Nitzschia bicapitata and N. interruptestriata, main contributors to Group 1, are common components of the open-ocean, nutrient-poor waters of tropical and subtropical areas of the world's oceans during periods of productivity collapse, following the shutdown of nutrient entrainment and the onset of stratification (Romero et al 1999(Romero et al , 2000. Similarly, Koning et al (2001) associated high numbers of N. bicapitata off Somalia with the retreating monsoonal upwelling in the western Indian Ocean.…”

Section: Intermonsoonmentioning

confidence: 98%

“…Based on net samples collected during the Indian Ocean Expedition of the RV 'Meteor', took an inventory of all diatom species encountered within an extensive working area along the NE African coast, the Persian Gulf, the Gulf of Oman and the western coast of India, and included remarks on the distribution and ecology of these species. Koning et al (2001) studied the diatom composition of settling particles collected in sediment traps off Somalia, NW Indian Ocean. In this area, diatoms represented > 90% of the total siliceous microorganisms.…”

Section: Introductionmentioning

confidence: 99%

“…In this area, diatoms represented > 90% of the total siliceous microorganisms. A distinct succession of seasonal diatom species of 'pre-upwellers', 'upwellers' and 'oceanic species' occurred off Somalia (Koning et al 2001). Less is known, however, about the seasonal dynamics of diatom populations and the contribution of diatoms to primary production and opal fluxes in the tropical SE Indian Ocean.…”

Section: Introductionmentioning

confidence: 99%

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Effects of hydrographic and climatic forcing on diatom production and export in the tropical southeastern Indian Ocean

Romero¹,

Rixen²,

Herunadi³

2009

Mar. Ecol. Prog. Ser.

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“…These spores bear a striking resemblance to modern Hyalochaete Chaetoceros resting spores, which currently comprise the bulk of biosiliceous sediments underlying zones of coastal upwelling and are indicative of highly productive environments (Bull and Kemp, 1995;Pike and Kemp, 1996b;Thunell, 1998;Koning et al, 2001). In a multidisciplinary study in the southern Benguela Current system, vegetative cells of Chaetoceros spp.…”

Section: Chaetoceros Spp-type Sporesmentioning

confidence: 99%

Late Cretaceous seasonal palaeoclimatology and diatom palaeoecology from laminated sediments

Davies

Kemp

2016

Cretaceous Research

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Laminated diatom-rich marine sediments from California and the Arctic Ocean provide a window into the seasonal climate and oceanography of the mid-and high-latitude Late Cretaceous. These remarkable shallow-buried sediments constitute palaeo-sediment traps that record exceptionally well-preserved sequential biogenic and lithogenic flux events. Many of the diatom laminae are composed of a few dominant taxa, and we use a species-based approach for palaeoecological interpretation. Contrary to many earlier interpretations, results indicate that both sites preserve a major flux of taxa adapted to exploit a strongly stratified ocean. The uppermost Maastrichtian Marca Shale of California records a seasonal cycle initiated with a spring bloom flux of diatom resting spores followed by a summer lithogenic sediment input likely driven by monsoonal storms providing river runoff and aeolian input. This is followed by a dominant diatom flux of species that thrived in the summer stratification in deep chlorophyll maxima and were sedimented in the fall when this stratification broke down. Dominant taxa comprising this group include Hemiaulus, Stephanopyxis, Stellarima and Rhizosolenia. The uppermost Campanian CESAR 6 core from the Arctic Alpha Ridge, records a spring bloom flux of resting spores followed by a more dominant summer and fall flux of diatom vegetative cells which were likely concentrated in subsurface summer blooms that generated a "summer export pulse" and by the breakdown of stratification in the fall that gave massive flux of deep chlorophyll maxima species in the fall dump. The dominance and diversity of Hemiaulus in the CESAR 6 core together with widespread evidence of N 2 -fixation may indicate that some diatom blooms were powered by intracellular N 2 -fixing cyanobacteria as in the modern oligotrophic ocean. Thin lenses of fine lithogenic sediment that occur mostly in the spring layer represent rafting by winter sea ice and support other evidence that suggests intermittent winter freezing in the Late Cretaceous Arctic.Keywords: Late Cretaceous; Diatom blooms; Paleoecology; California; Arctic; Sea Ice 3 1.Introduction Laminated pelagic and hemipelagic marine sediments often constitute "palaeosediment traps" that preserve sequential flux events from which the ancient seasonal flux cycle may be reconstructed. They commonly preserve both the biogenic flux events from surface ocean productivity and also the terrigenous sediment input common in hemipelagic or marginal settings. Within rare, exceptionally well-preserved Cretaceous sediments, fossil diatom algae record the seasonal cycle of marine production and flux to the sea bed. In the modern ocean diatom algae are the dominant, bloom-forming phytoplankton in many environments and are key players in the marine biological carbon pump. The relative contribution of diatoms to total primary production has been estimated to range from 35% in the oligotrophic oceans to 75% in the coastal zone and in the Antarctic (Nelson et al., 1995), while their contribution...

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Selective preservation of upwelling-indicating diatoms in sediments off Somalia, NW Indian Ocean

Cited by 51 publications

References 37 publications

Contribution of changes in opal productivity and nutrient distribution in the coastal upwelling systems to Late Pliocene/Early Pleistocene climate cooling

Contribution of changes in opal productivity and nutrient distribution in the coastal upwelling systems to Late Pliocene/Early Pleistocene climate cooling

Effects of hydrographic and climatic forcing on diatom production and export in the tropical southeastern Indian Ocean

Late Cretaceous seasonal palaeoclimatology and diatom palaeoecology from laminated sediments

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