Response of nannoplankton to early Eocene ocean destratification

Schneider, Leah; Bralower, Timothy J.; Kump, Lee R.

doi:10.1016/j.palaeo.2011.06.018

Cited by 38 publications

(53 citation statements)

References 33 publications

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“…The concentration of alkenones within lipid bodies in marine haptophytes [ Eltgroth et al ., ] provides evidence of their role as storage lipids, which afford an advantage for survival where environmental factors (i.e., light, nutrients, and temperature) lead to seasonal constraints on productivity. Hence, high‐latitude algal species capable of producing alkenones, including Reticulofenestra , were likely participants in the equatorward migration of calcareous nannoplankton [ Aubry , ; Schneider et al ., ] that accompanied steadfast global cooling during the middle Eocene [ Bijl et al ., ; Hollis et al ., ], only interrupted by the ~0.6 Myr warming interval recognized as the Middle Eocene Climatic Optimum (MECO) [ Bijl et al ., ]. The changes in trophic structure associated with (i) reduced thermal stratification, (ii) increases in productivity facilitated by an enhanced influx of nutrients [ Schneider et al ., ], and (iii) concomitant strengthening of latitudinal temperature gradients [ Bijl et al ., ] would likely favor calcareous nannoplankton species with eurythermal and/or eurytrophic capabilities, such as Reticulofenestra [ Agnini et al ., ; Shcherbinina , ].…”

Section: Timing Of Innovation In Alkenone Biosynthesis and Climate Chmentioning

confidence: 99%

“…Hence, high‐latitude algal species capable of producing alkenones, including Reticulofenestra , were likely participants in the equatorward migration of calcareous nannoplankton [ Aubry , ; Schneider et al ., ] that accompanied steadfast global cooling during the middle Eocene [ Bijl et al ., ; Hollis et al ., ], only interrupted by the ~0.6 Myr warming interval recognized as the Middle Eocene Climatic Optimum (MECO) [ Bijl et al ., ]. The changes in trophic structure associated with (i) reduced thermal stratification, (ii) increases in productivity facilitated by an enhanced influx of nutrients [ Schneider et al ., ], and (iii) concomitant strengthening of latitudinal temperature gradients [ Bijl et al ., ] would likely favor calcareous nannoplankton species with eurythermal and/or eurytrophic capabilities, such as Reticulofenestra [ Agnini et al ., ; Shcherbinina , ]. Hence, the migration of Reticulofenestra to lower latitudes driven by global cooling [ Schneider et al ., ], and its subsequent dominance [ Weinbaum‐Hefetz and Benjamini , ], was perhaps facilitated by its biosynthetic ability to produce alkenones, which enabled this genus to thrive over a broad latitudinal range.…”

Section: Timing Of Innovation In Alkenone Biosynthesis and Climate Chmentioning

confidence: 99%

“…The changes in trophic structure associated with (i) reduced thermal stratification, (ii) increases in productivity facilitated by an enhanced influx of nutrients [ Schneider et al ., ], and (iii) concomitant strengthening of latitudinal temperature gradients [ Bijl et al ., ] would likely favor calcareous nannoplankton species with eurythermal and/or eurytrophic capabilities, such as Reticulofenestra [ Agnini et al ., ; Shcherbinina , ]. Hence, the migration of Reticulofenestra to lower latitudes driven by global cooling [ Schneider et al ., ], and its subsequent dominance [ Weinbaum‐Hefetz and Benjamini , ], was perhaps facilitated by its biosynthetic ability to produce alkenones, which enabled this genus to thrive over a broad latitudinal range.…”

Section: Timing Of Innovation In Alkenone Biosynthesis and Climate Chmentioning

confidence: 99%

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Climatic influences on the Paleogene evolution of alkenones

Brassell

2014

Paleoceanography

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Application of the alkenone paleotemperature proxy (U K' 37 ) for marine sediments is typically constrained by three factors: (i) an absence of alkatrienones in sediments deposited where ocean temperatures exceed~28°C, (ii) loss of alkenones in thermally altered sediments, and (iii) poor preservation of alkenone signals due to oxidative degradation. In addition, there appears to be a temporal limit on the occurrence of alkatrienones, which are conspicuously absent in all alkenone-containing sediments from the early Aptian to the immediate aftermath of the Early Eocene Climatic Optimum (EECO) when they first appeared in Arctic Ocean sediments. Compilation of reported and previously unpublished alkenone distributions for the Paleogene coupled with assessment of co-occurring calcareous nannoplankton genera within the Noelaerhabdaceae provide evidence that evolutionary developments in alkenone occurrences include biosynthetic responses likely triggered by climate change. The timing of emergence of alkatrienones post-EECO and their subsequent appearance at all latitudes during the middle Eocene accompanies expansion of the calcareous nannoplankton genus Reticulofenestra coincident with significant climate-driven changes in oceanic conditions, including (i) modification of trophic structure associated with weakened thermal stratification, (ii) higher productivity facilitated by enhanced nutrient influx, and (iii) changes in seasonality, initially at high latitudes, related to greater latitudinal temperature gradients. Collectively, these changes would serve to favor eurythermal/eurytrophic algae, like Reticulofenestra, with a biomechanism to store energy through production of lipid bodies rich in alkenones during episodes of higher nutrient availability. This ability likely enhanced the viability of this marine haptophyte when nutrients were limiting, ultimately ensuring its evolutionary success.

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Section: Timing Of Innovation In Alkenone Biosynthesis and Climate Chmentioning

confidence: 99%

Section: Timing Of Innovation In Alkenone Biosynthesis and Climate Chmentioning

confidence: 99%

Section: Timing Of Innovation In Alkenone Biosynthesis and Climate Chmentioning

confidence: 99%

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Climatic influences on the Paleogene evolution of alkenones

Brassell

2014

Paleoceanography

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“…Nannoplankton were very diverse in the early Eocene, the warmest and likely most stratified interval in the Cenozoic [ Bown et al ., ; Hilting et al ., ]. After this warm period, nannoplankton experienced a significant turnover in the middle Eocene that was largely driven by a decrease in stratification and shoaling of the nutricline [ Schneider et al ., ]. This interval, and the late Eocene in particular, saw a drastic decrease in Discoaster diversity [ Bown et al ., ] supporting our conclusion that the spatially restricted, deep niche of this genus was susceptible to changing mixing intensity.…”

Section: Discussionmentioning

confidence: 99%

“…NMS is an ordination technique [e.g., Kenkel and Orlólci, 1986;Clarke, 1993;Legendre and Legendre, 1998] that has been routinely applied in modern microbial ecological studies to determine community structure [e.g., Giovannoni and Stingl, 2005;Van der Gucht et al, 2005;Ramette, 2007]. NMS has also been shown to be a powerful and robust technique in paleoecological applications [e.g., DiMichele and Aronson, 1992;Shi, 1993;Olszewski and Patzkowsky, 2001;Holland and Patzkowsky, 2004;Jiang et al, 2010;Schneider et al, 2011Schneider et al, , 2013.…”

Section: Introductionmentioning

confidence: 99%

The relationship between environmental change and the extinction of the nannoplankton Discoaster in the early Pleistocene

Schueth

Bralower

2015

Paleoceanography

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The long-ranging nannoplankton genus Discoaster went extinct in the early Pleistocene, one of the most significant events in the Cenozoic nannofossil record. The causal factors of this extinction are poorly constrained, at least partially because the ecology of Discoaster is not well understood. We investigate the relationship between the extinction and environmental changes by comparing a suite of high-resolution nannofossil assemblage data at four Ocean Drilling Program sites to published environmental proxy records. Through the use of multivariate analysis, we determine Discoaster shared environmental preferences with the extant species Florisphaera profunda which thrives in the lower photic zone near the nutricline in locations where the water column is stratified. We show that the last occurrence of Discoaster was globally diachronous, rather than synchronous as previously thought, and likely took place in the equatorial Atlantic Ocean. We propose that the demise of Discoaster was a two-stage process. A decrease in sea surface temperatures and increase in climate variability led to a global decline in Discoaster abundance. The extinction event itself correlates to shoaling of the nutricline as signified by a decrease in the carbon isotopic gradient between surface and thermocline foraminifera. We hypothesize that the combination of global cooling and a shoaling of the nutricline greatly reduced Discoaster's deepwater niche and contributed to its extinction. This may suggest that ocean stratification and the depth of the nutricline are important contributors to overall nannoplankton diversity.

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