Kronz, Andreas

[["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Paleoceanography and Paleoclimatology"],["dc.bibliographiccitation.volume","37"],["dc.contributor.author","Leclerc, Natasha"],["dc.contributor.author","Halfar, Jochen"],["dc.contributor.author","Hetzinger, Steffen"],["dc.contributor.author","Chan, Phoebe T. W."],["dc.contributor.author","Adey, Walter"],["dc.contributor.author","Tsay, Alexandra"],["dc.contributor.author","Brossier, Eric"],["dc.contributor.author","Kronz, Andreas"],["dc.date.accessioned","2022-04-01T10:02:36Z"],["dc.date.available","2022-04-01T10:02:36Z"],["dc.date.issued","2021"],["dc.identifier.doi","10.1029/2021PA004286"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/105959"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-530"],["dc.relation.eissn","2572-4525"],["dc.relation.issn","2572-4517"],["dc.rights.uri","http://onlinelibrary.wiley.com/termsAndConditions#vor"],["dc.title","Suitability of the Coralline Alga Clathromorphum compactum as an Arctic Archive for Past Sea Ice Cover"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","22107"],["dc.bibliographiccitation.issue","C9"],["dc.bibliographiccitation.journal","JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS"],["dc.bibliographiccitation.lastpage","22116"],["dc.bibliographiccitation.volume","105"],["dc.contributor.author","Halfar, Jochen"],["dc.contributor.author","Zack, Thomas"],["dc.contributor.author","Kronz, A."],["dc.contributor.author","Zachos, J. C."],["dc.date.accessioned","2018-11-07T10:10:23Z"],["dc.date.available","2018-11-07T10:10:23Z"],["dc.date.issued","2000"],["dc.description.abstract","We investigated rhodoliths (coralline red algae) from a subtropical locality in the Gulf of California (Lithothamnium crassiusculum) and a subarctic locality in Newfoundland (Lithothamnium glaciale) for their potential as paleoenvironmental archives using microanalytical geochemical techniques to measure variations in delta(18)O, Mg, and Ca. Rhodoliths are potentially well suited as recorders of shallow water paleoenvironmental signals because they (1) have worldwide distribution from the tropics to polar regions, (2) are long lived from decades to centuries, and (3) display well-developed growth bands. Our results indicate that rhodolith growth bands preserve ultrahigh-resolution records of paleoceanographic-paleoclimatic change and likely constitute an important new archive for reconstructing the paleoenvironmental history of littoral-neritic areas in which these algae are found. The delta(18)O content of individually sampled rhodolith growth bands ranges from -2.4 to -4.6 parts per thousand in L. crassiusculum and from -3.2 to -0.3 parts per thousand in L, glaciale. In both cases, the range of delta(18)O values suggests a slightly lower amplitude of variation in sea surface temperature than that actually measured in the ocean at the two study sites. Both L, crassiusculum ann L, glaciale show a negative offset from isotopic equilibrium. Electron microprobe analysis of magnesium and calcium in growth bands reveals cyclic variations with values ranging between 7.7-18.5 mol % MgCO3 in L. glaciale and 13.2-22.5 mol % MgCO3 in L. crassiusculum. In addition, electron microprobe element maps highlight individual growth bands, provide a powerful approach to study rhodolith formation, and indicate that the specimens we analyzed have Vertical growth rates of 250-450 mu m/yr."],["dc.identifier.doi","10.1029/1999JC000128"],["dc.identifier.isi","000089369600017"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/39844"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Geophysical Union"],["dc.relation.issn","2169-9291"],["dc.relation.issn","2169-9275"],["dc.title","Growth and high-resolution paleoenvironmental signals of rhodoliths (coralline red algae): A new biogenic archive"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","375"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Arctic Antarctic and Alpine Research"],["dc.bibliographiccitation.lastpage","387"],["dc.bibliographiccitation.volume","47"],["dc.contributor.author","Bougeois, Laurie"],["dc.contributor.author","Williams, Branwen"],["dc.contributor.author","Halfar, Jochen"],["dc.contributor.author","Konar, Brenda"],["dc.contributor.author","Adey, Walter H."],["dc.contributor.author","Kronz, Andreas"],["dc.contributor.author","Wortmann, Ulrich G."],["dc.date.accessioned","2018-11-07T09:57:34Z"],["dc.date.available","2018-11-07T09:57:34Z"],["dc.date.issued","2015"],["dc.description.abstract","Records of high resolution climate variability in the past are essential to understanding the climate change observed today. This is particularly true for Arctic regions, which are rapidly warming. Prior to instrumental data, proxy records can be extracted from high-latitude climate archives to provide critical records of past Arctic climate variability. Here, we investigate the feasibility of extracting records of climate and environmental variability from the skeleton of the crustose coralline alga Leptophytum foecundum from offshore the Sagavanirktok River in the Beaufort Sea. Although this alga forms an annually banded skeleton, age chronologies were established with difficulty due to the large uncalcified reproductive structures relative to low annual growth rates. Average measurements of skeletal Mg content, delta O-18(alga) values, and delta C-13(alga) values were consistent among the analyzed specimens, but time series of these parameters only significantly correlated between two of the collected specimens for delta O-18(alga). No clear trends in environmental variability explained the patterns in the skeletal geochemistry over time. This suggests that ambient seawater combined with freshwater from the Sagavanirktok River drives the geochemistry of L. foecundum at this site. Thus, coralline algal specimens located near variable sources of low-salinity waters are not ideal organisms to use as proxy archives."],["dc.identifier.doi","10.1657/AAAR0014-061"],["dc.identifier.isi","000355627500018"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/37186"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Inst Arctic Alpine Res"],["dc.relation.issn","1938-4246"],["dc.relation.issn","1523-0430"],["dc.title","Does the coralline alga Leptophytum foecundum (Kjellman) capture paleoenvironmental variability in the Arctic Ocean?"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","406"],["dc.bibliographiccitation.issue","5-6"],["dc.bibliographiccitation.journal","Palaios"],["dc.bibliographiccitation.lastpage","412"],["dc.bibliographiccitation.volume","24"],["dc.contributor.author","Hetzinger, Steffen"],["dc.contributor.author","Halfar, Jochen"],["dc.contributor.author","Kronz, Andreas"],["dc.contributor.author","Steneck, Robert S."],["dc.contributor.author","Adey, Walter H."],["dc.contributor.author","Lebednik, Phillip A."],["dc.contributor.author","Schoene, Bernd R."],["dc.date.accessioned","2018-11-07T08:30:32Z"],["dc.date.available","2018-11-07T08:30:32Z"],["dc.date.issued","2009"],["dc.description.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 similar to 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 delta(18)O 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-delta(18)O, 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."],["dc.identifier.doi","10.2110/palo.2008.p08-116r"],["dc.identifier.isi","000266707400016"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/16914"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Sepm-soc Sedimentary Geology"],["dc.relation.issn","0883-1351"],["dc.title","HIGH-RESOLUTION MG/CA RATIOS IN A CORALLINE RED ALGA AS A PROXY FOR BERING SEA TEMPERATURE VARIATIONS FROM 1902 TO 1967"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","19737"],["dc.bibliographiccitation.issue","49"],["dc.bibliographiccitation.journal","PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA"],["dc.bibliographiccitation.lastpage","19741"],["dc.bibliographiccitation.volume","110"],["dc.contributor.author","Halfar, Jochen"],["dc.contributor.author","Adey, Walter H."],["dc.contributor.author","Kronz, Andreas"],["dc.contributor.author","Hetzinger, Steffen"],["dc.contributor.author","Edinger, Evan"],["dc.contributor.author","Fitzhugh, William W."],["dc.date.accessioned","2018-11-07T09:16:40Z"],["dc.date.available","2018-11-07T09:16:40Z"],["dc.date.issued","2013"],["dc.description.abstract","Northern Hemisphere sea ice has been declining sharply over the past decades and 2012 exhibited the lowest Arctic summer sea-ice cover in historic times. Whereas ongoing changes are closely monitored through satellite observations, we have only limited data of past Arctic sea-ice cover derived from short historical records, indirect terrestrial proxies, and low-resolution marine sediment cores. A multicentury time series from extremely long-lived annual increment-forming crustose coralline algal buildups now provides the first high-resolution in situ marine proxy for sea-ice cover. Growth and Mg/Ca ratios of these Arctic-wide occurring calcified algae are sensitive to changes in both temperature and solar radiation. Growth sharply declines with increasing sea-ice blockage of light from the benthic algal habitat. The 646-y multisite record from the Canadian Arctic indicates that during the Little Ice Age, sea ice was extensive but highly variable on subdecadal time scales and coincided with an expansion of ice-dependent Thule/Labrador Inuit sea mammal hunters in the region. The past 150 y instead have been characterized by sea ice exhibiting multidecadal variability with a long-term decline distinctly steeper than at any time since the 14th century."],["dc.identifier.doi","10.1073/pnas.1313775110"],["dc.identifier.isi","000327744900031"],["dc.identifier.pmid","24248344"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/27983"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Natl Acad Sciences"],["dc.relation.issn","0027-8424"],["dc.title","Arctic sea-ice decline archived by multicentury annual-resolution record from crustose coralline algal proxy"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1447"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","Climate Dynamics"],["dc.bibliographiccitation.lastpage","1455"],["dc.bibliographiccitation.volume","39"],["dc.contributor.author","Hetzinger, Steffen"],["dc.contributor.author","Halfar, Jochen"],["dc.contributor.author","Mecking, J. V."],["dc.contributor.author","Keenlyside, N. S."],["dc.contributor.author","Kronz, A."],["dc.contributor.author","Steneck, Robert S."],["dc.contributor.author","Adey, Walter H."],["dc.contributor.author","Lebednik, Phillip A."],["dc.date.accessioned","2018-11-07T09:06:27Z"],["dc.date.available","2018-11-07T09:06:27Z"],["dc.date.issued","2012"],["dc.description.abstract","Decadal- to multidecadal variability in the extra-tropical North Pacific is evident in 20th century instrumental records and has significant impacts on Northern Hemisphere climate and marine ecosystems. Several studies have discussed a potential linkage between North Pacific and Atlantic climate on various time scales. On decadal time scales no relationship could be confirmed, potentially due to sparse instrumental observations before 1950. Proxy data are limited and no multi-centennial high-resolution marine geochemical proxy records are available from the subarctic North Pacific. Here we present an annually-resolved record (1818-1967) of Mg/Ca variations from a North Pacific/Bering Sea coralline alga that extends our knowledge in this region beyond available data. It shows for the first time a statistically significant link between decadal fluctuations in sea-level pressure in the North Pacific and North Atlantic. The record is a lagged proxy for decadal-scale variations of the Aleutian Low. It is significantly related to regional sea surface temperature and the North Atlantic Oscillation (NAO) index in late boreal winter on these time scales. Our data show that on decadal time scales a weaker Aleutian Low precedes a negative NAO by several years. This atmospheric link can explain the coherence of decadal North Pacific and Atlantic Multidecadal Variability, as suggested by earlier studies using climate models and limited instrumental data."],["dc.identifier.doi","10.1007/s00382-011-1229-4"],["dc.identifier.isi","000308722900014"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/25564"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","1432-0894"],["dc.relation.issn","0930-7575"],["dc.title","Marine proxy evidence linking decadal North Pacific and Atlantic climate"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","81"],["dc.bibliographiccitation.issue","1-2"],["dc.bibliographiccitation.journal","Palaeogeography Palaeoclimatology Palaeoecology"],["dc.bibliographiccitation.lastpage","94"],["dc.bibliographiccitation.volume","302"],["dc.contributor.author","Hetzinger, Steffen"],["dc.contributor.author","Halfar, Jochen"],["dc.contributor.author","Zack, Thomas"],["dc.contributor.author","Gamboa, G."],["dc.contributor.author","Jacob, Dorrit E."],["dc.contributor.author","Kunz, B. E."],["dc.contributor.author","Kronz, A."],["dc.contributor.author","Adey, Walter H."],["dc.contributor.author","Lebednik, Phillip A."],["dc.contributor.author","Steneck, Robert S."],["dc.date.accessioned","2018-11-07T08:58:35Z"],["dc.date.available","2018-11-07T08:58:35Z"],["dc.date.issued","2011"],["dc.description.abstract","We have investigated the trace elemental composition in the skeleta of two specimens of attached-living coralline algae of the species Clathromorphum compactum from the North Atlantic (Newfoundland) and Clathromorphum nereostratum from the North Pacific/Bering Sea region (Amchitka Island, Aleutians). Samples were analyzed using Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (IA-ICP-MS) yielding for the first time continuous individual trace elemental records of up to 69 years in length. The resulting algal Mg/Ca, Sr/Ca, U/Ca, and Ba/Ca ratios are reproducible within individual sample specimens. Algal Mg/Ca ratios were additionally validated by electron microprobe analyses (Amchitka sample). Algal Sr/Ca, U/Ca, and Ba/Ca ratios were compared to algal Mg/Ca ratios, which previously have been shown to reliably record sea surface temperature (SST). Ratios of Sr/Ca from both Clathromorphum species show a strong positive correlation to temperature-dependent Mg/Ca ratios, implying that seawater temperature plays an important role in the incorporation of Sr into algal calcite. Linear Sr/Ca-SST regressions have provided positive, but weaker relationships as compared to Mg/Ca-SST relationships. Both, algal Mg/Ca and Sr/Ca display clear seasonal cycles. Inverse correlations were found between algal Mg/Ca and U/Ca, Ba/Ca, and correlations to SST are weaker than between Mg/Ca, Sr/Ca and SST. This suggests that the incorporation of U and Ba is influenced by other factors aside from temperature. (C) 2010 Elsevier B.V. All rights reserved."],["dc.identifier.doi","10.1016/j.palaeo.2010.06.004"],["dc.identifier.isi","000288776700009"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/23677"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.relation.issn","1872-616X"],["dc.relation.issn","0031-0182"],["dc.title","High-resolution analysis of trace elements in crustose coralline algae from the North Atlantic and North Pacific by laser ablation ICP-MS"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2617"],["dc.bibliographiccitation.issue","8"],["dc.bibliographiccitation.journal","Journal of Geophysical Research. G, Biogeosciences"],["dc.bibliographiccitation.lastpage","2626"],["dc.bibliographiccitation.volume","123"],["dc.contributor.author","Williams, Siobhan"],["dc.contributor.author","Halfar, Jochen"],["dc.contributor.author","Zack, Thomas"],["dc.contributor.author","Hetzinger, Steffen"],["dc.contributor.author","Blicher, Martin"],["dc.contributor.author","Juul-Pedersen, Thomas"],["dc.contributor.author","Kronz, Andreas"],["dc.contributor.author","Noël, Brice"],["dc.contributor.author","van den Broeke, Michiel"],["dc.contributor.author","van de Berg, Willem Jan"],["dc.date.accessioned","2020-12-10T18:09:22Z"],["dc.date.available","2020-12-10T18:09:22Z"],["dc.date.issued","2018"],["dc.identifier.doi","10.1029/2018JG004385"],["dc.identifier.issn","2169-8953"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/73633"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.title","Coralline Algae Archive Fjord Surface Water Temperatures in Southwest Greenland"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","L07702"],["dc.bibliographiccitation.issue","7"],["dc.bibliographiccitation.journal","Geophysical Research Letters"],["dc.bibliographiccitation.volume","34"],["dc.contributor.author","Halfar, Jochen"],["dc.contributor.author","Steneck, Robert S."],["dc.contributor.author","Schoene, Bernd R."],["dc.contributor.author","Moore, G. W. K."],["dc.contributor.author","Joachimski, Michael M."],["dc.contributor.author","Kronz, Andreas"],["dc.contributor.author","Fietzke, Jan"],["dc.contributor.author","Estes, James"],["dc.date.accessioned","2018-11-07T11:03:16Z"],["dc.date.available","2018-11-07T11:03:16Z"],["dc.date.issued","2007"],["dc.description.abstract","While recent changes in subarctic North Pacific climate had dramatic effects on ecosystems and fishery yields, past climate dynamics and teleconnection patterns are poorly understood due to the absence of century-long high-resolution marine records. We present the first 117-year long annually resolved marine climate history from the western Bering Sea/Aleutian Island region using information contained in the calcitic skeleton of the long-lived crustose coralline red alga Clathromorphum nereostratum, a previously unused climate archive. The skeletal delta O-18-time series indicates significant warming and/ or freshening of surface waters after the middle of the 20th century. Furthermore, the time series is spatiotemporally correlated with Pacific Decadal Oscillation (PDO) and tropical El Nino-Southern Oscillation (ENSO) indices. Even though the western Bering Sea/Aleutian Island region is believed to be outside the area of significant marine response to ENSO, we propose that an ENSO signal is transmitted via the Alaskan Stream from the Eastern North Pacific, a region of known ENSO teleconnections."],["dc.identifier.doi","10.1029/2006GL028811"],["dc.identifier.isi","000245578300002"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/51578"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Geophysical Union"],["dc.relation.issn","1944-8007"],["dc.relation.issn","0094-8276"],["dc.title","Coralline alga reveals first marine record of subarctic North Pacific climate change"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","5745"],["dc.bibliographiccitation.issue","19"],["dc.bibliographiccitation.journal","Biogeosciences"],["dc.bibliographiccitation.lastpage","5759"],["dc.bibliographiccitation.volume","15"],["dc.contributor.author","Williams, Siobhan"],["dc.contributor.author","Adey, Walter"],["dc.contributor.author","Halfar, Jochen"],["dc.contributor.author","Kronz, Andreas"],["dc.contributor.author","Gagnon, Patrick"],["dc.contributor.author","Bélanger, David"],["dc.contributor.author","Nash, Merinda"],["dc.date.accessioned","2020-12-10T18:47:52Z"],["dc.date.available","2020-12-10T18:47:52Z"],["dc.date.issued","2018"],["dc.identifier.doi","10.5194/bg-15-5745-2018"],["dc.identifier.eissn","1726-4189"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/78925"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.title","Effects of light and temperature on Mg uptake, growth, and calcification in the proxy climate archive <i>Clathromorphum</i> <i>compactum</i>"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]