HIGH-RESOLUTION MG/CA RATIOS IN A CORALLINE RED ALGA AS A PROXY FOR BERING SEA TEMPERATURE VARIATIONS FROM 1902 TO 1967

Year:

2009

Type of Publication:

Article

Authors:

HETZINGER, STEFFEN; HALFAR, JOCHEN; Kronz, Andreas; STENECK, ROBERT S.; ADEY, WALTER; LEBEDNIK, PHILLIP A.; SCHÖNE, BERND R.

Journal:

PALAIOS

Volume:

24

Number:

6

Pages:

406-412

BibTex:

@article{palo.2008.p08-116r, author = "STEFFEN HETZINGER and JOCHEN HALFAR and Andreas Kronz and ROBERT S. STENECK and WALTER ADEY and PHILLIP A. LEBEDNIK and BERND R. SCH{\"O}NE", abstract = "We present the first continuous, high-resolution record of Mg/Ca variations within an encrusting coralline red alga, Clathromorphum nereostratum, from Amchitka Island, Aleutian Islands. Mg/Ca ratios of individual growth increments were analyzed by measuring a single-point, electron-microprobe transect, yielding a resolution of ∼15 samples/year and a 65-year record (1902–1967) of variations. Results show that Mg/Ca ratios in the high-Mg calcite algal framework display pronounced annual cyclicity and archive late spring–late fall sea-surface temperatures (SST) corresponding to the main season of algal growth. Mg/Ca values correlate well to local SST, as well as to an air temperature record from the same region. High spatial correlation to large-scale SST variability in the subarctic North Pacific is observed, with patterns of strongest correlation following the direction of major oceanographic features that play a key role in the exchange of water masses between the North Pacific and the Bering Sea. Our data correlate well with a shorter Mg/Ca record from a second site, corroborating the ability of the alga to reliably record regional environmental signals. In addition, Mg/Ca ratios relate well to a 29-year δ18O time series measured on the same sample, providing additional support for the use of Mg in coralline red algae as a paleotemperature proxy that, unlike algal-δ18O, is not influenced by salinity fluctuations. Moreover, electron microprobe–based analysis enables higher sampling resolution and faster analysis, thus providing a promising approach for future studies of longer C. nereostratum records and applications to other coralline species.", doi = "10.2110/palo.2008.p08-116r", journal = "PALAIOS", number = "6", pages = "406-412", title = "{HIGH}-{RESOLUTION} {MG}/{CA} {RATIOS} {IN} {A} {CORALLINE} {RED} {ALGA} {AS} {A} {PROXY} {FOR} {BERING} {SEA} {TEMPERATURE} {VARIATIONS} {FROM} 1902 {TO} 1967", url = "http://palaios.sepmonline.org/content/24/6/406.abstract", volume = "24", year = "2009", }

Abstract:

We present the first continuous, high-resolution record of Mg/Ca variations within an encrusting coralline red alga, Clathromorphum nereostratum, from Amchitka Island, Aleutian Islands. Mg/Ca ratios of individual growth increments were analyzed by measuring a single-point, electron-microprobe transect, yielding a resolution of ∼15 samples/year and a 65-year record (1902–1967) of variations. Results show that Mg/Ca ratios in the high-Mg calcite algal framework display pronounced annual cyclicity and archive late spring–late fall sea-surface temperatures (SST) corresponding to the main season of algal growth. Mg/Ca values correlate well to local SST, as well as to an air temperature record from the same region. High spatial correlation to large-scale SST variability in the subarctic North Pacific is observed, with patterns of strongest correlation following the direction of major oceanographic features that play a key role in the exchange of water masses between the North Pacific and the Bering Sea. Our data correlate well with a shorter Mg/Ca record from a second site, corroborating the ability of the alga to reliably record regional environmental signals. In addition, Mg/Ca ratios relate well to a 29-year δ18O time series measured on the same sample, providing additional support for the use of Mg in coralline red algae as a paleotemperature proxy that, unlike algal-δ18O, is not influenced by salinity fluctuations. Moreover, electron microprobe–based analysis enables higher sampling resolution and faster analysis, thus providing a promising approach for future studies of longer C. nereostratum records and applications to other coralline species.