High-Resolution Mg/Ca Ratios in a Coralline Red Alga as a Proxy for Bering Sea Temperature Variations From 1902 to 1967

Geochimica et Cosmochimica Acta

DeLong

et al. 2014

Self Cite

specimen and multi-site calibration of Aleutian coralline algal Mg/Ca to sea surface temperature, Geochimica et Cosmochimica Acta (2014), doi: http://dx.doi.org/10.1016/j.gca. 2014.04.006 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Section: Specimen Analysismentioning

confidence: 91%

“…Ocean including the North Atlantic Oscillation (Halfar et al, 2007;Hetzinger et al, 2009;Hetzinger et al, 2012).…”

Section: Study Area and Climatologymentioning

confidence: 99%

Section: Seasonal Variability In Sst Drives Fluctuations In Mg/ca Valmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Multi-specimen and multi-site calibration of Aleutian coralline algal Mg/Ca to sea surface temperature

Williams

Geochimica et Cosmochimica Acta

DeLong

et al. 2014

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Micro‐computed tomography: Applications for high‐resolution skeletal density determinations: An example using annually banded crustose coralline algae

Chan

Geochem Geophys Geosyst

Norley

et al. 2017

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Warming and acidification of the world's oceans are expected to have widespread consequences for marine biodiversity and ecosystem functioning. However, due to the relatively short record of instrumental observations, one has to rely upon geochemical and physical proxy information stored in biomineralized shells and skeletons of calcareous marine organisms as in situ recorders of past environments. Of particular interest is the response of marine calcifiers to ocean acidification through the examination of structural growth characteristics. Here we demonstrate the application of micro‐computed tomography (micro‐CT) for three‐dimensional visualization and analysis of growth, skeletal density, and calcification in a slow‐growing, annually banded crustose coralline alga Clathromorphum nereostratum (increment width ∼380 µm). X‐ray images and time series of skeletal density were generated at 20 µm resolution and rebinned to 40, 60, 80, and 100 µm for comparison in a sensitivity analysis. Calcification rates were subsequently calculated as the product of density and growth (linear extension). While both skeletal density and calcification rates do not significantly differ at varying spatial resolutions (the latter being strongly influenced by growth rates), clear visualization of micron‐scale growth features and the quantification of structural changes on subannual time scales requires higher scanning resolutions. In the present study, imaging at 20 µm resolution reveals seasonal cycles in density that correspond to summer/winter variations in skeletal structure observed using scanning electron microscopy (SEM). Micro‐CT is a fast, nondestructive, and high‐resolution technique for structural and morphometric analyses of temporally banded paleoclimate archives, particularly those that exhibit slow or compressed growth or micron‐scale structures.

North Pacific twentieth century decadal‐scale variability is unique for the past 342 years

Williams

Geophysical Research Letters

DeLong

et al. 2017

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Reconstructed sea surface temperatures (SSTs) derived from Mg/Ca measurements in nine encrusting coralline algal skeletons from the Aleutian archipelago in the northernmost Pacific Ocean reveal an overall increase in SST from 1665 to 2007. In the Aleutian SST reconstruction, decadal‐scale variability is a transient feature present during the 1700s and early 1800s and then fully emerging post‐1950. SSTs vary coherently with available instrument records of cyclone variance and vacillate in and out of coherence with multicentennial Pacific Northwest drought reconstructions as a response to SST‐driven alterations of storm tracks reaching North America. These results indicate that an influence of decadal‐scale variability on the North Pacific storm tracks only became apparent during the midtwentieth century. Furthermore, what has been assumed as natural variability in the North Pacific, based on twentieth century instrumental data, is not consistent with the long‐term natural variability evident in reconstructed SSTs predating the anthropogenic influence.