Spatiotemporal variability in the O-18-salinity relationship of seawater across the tropical Pacific Ocean

The relationship between salinity and the stable oxygen isotope ratio of seawater (δ18Osw) is of utmost importance to the quantitative reconstruction of past changes in salinity from δ18O values of marine carbonates. This relationship is often considered to be uniform across water masses, but the constancy of the δ18Osw-salinity relationship across space and time remains uncertain, as δ18Osw responds to varying atmospheric vapor sources and pathways, while salinity does not. Here we present new δ18Osw-salinity data from sites spanning the tropical Pacific Ocean. New data from Palau, Papua New Guinea, Kiritimati, and Galápagos show slopes ranging from 0.09 ‰/psu in the Galápagos to 0.32‰/psu in Palau. The slope of the δ18Osw-salinity relationship is higher in the western tropical Pacific versus the eastern tropical Pacific in observations and in two isotope-enabled climate model simulations. A comparison of δ18Osw-salinity relationships derived from short-term spatial surveys and multiyear time series at Papua New Guinea and Galápagos suggests spatial relationships can be substituted for temporal relationships at these sites, at least within the time period of the investigation. However, the δ18Osw-salinity relationship varied temporally at Palau, likely in response to water mass changes associated with interannual El Niño–Southern Oscillation (ENSO) variability, suggesting nonstationarity in this local δ18Osw-salinity relationship. Applying local δ18Osw-salinity relationships in a coral δ18O forward model shows that using a constant, basinwide δ18Osw-salinity slope can both overestimate and underestimate the contribution of δ18Osw to carbonate δ18O variance at individual sites in the western tropical Pacific.We are grateful for the dedicated water samplers who enabled this research: Lori J. Bell and Gerda Ucharm of the Coral Reef Research Foundation, Palau; Rosa Maritza Motoche Gonzalez and the Fuerza Aerea Ecuatoriana, Santa Cruz, Galapagos, Ecuador; Taonateiti Kabiri and the students of Tennessee Primary School, London, Kiritimati; and the Manus Weather Observers, U.S. Department of Energy ARM Climate Research Facility, Manus, Papua New Guinea. We would like to thank the Galapagos National Park, the Kiritimati Ministry of Environment Lands and Agricultural Development for sample permits, and the Charles Darwin Research Station for logistical support. Funding sources for this work includes NSF-AGS-PF 1049664 to J.L.C., NSF P2C2-1203785 to K.M.C., J.L.C., and D.N. This research was also supported by the Office of Biological and Environment Research of the U.S. Department of Energy as part of the Atmospheric Radiation Measurement Climate Research Facility. Isotope data are available as supporting information associated with the manuscript. (1049664 - NSF-AGS-PF; P2C2-1203785 - NSF; Office of Biological and Environment Research of the U.S. Department of Energy as part of the Atmospheric Radiation Measurement Climate Research Facility

Coral skeleton P/Ca proxy for seawater phosphate: Multi-colony calibration with a contemporaneous seawater phosphate record

A geochemical proxy for surface ocean nutrient concentrations recorded in coral skeleton could provide new insight into the connections between sub-seasonal to centennial scale nutrient dynamics, ocean physics, and primary production in the past. Previous work showed that coralline P/Ca, a novel seawater phosphate proxy, varies synchronously with annual upwelling-driven cycles in surface water phosphate concentration. However, paired contemporaneous seawater phosphate time-series data, needed for rigorous calibration of the new proxy, were lacking. Here we present further development of the P/Ca proxy in Porites lutea and Montastrea sp. corals, showing that skeletal P/Ca in colonies from geographically distinct oceanic nutrient regimes is a linear function of seawater phosphate (PO4 SW) concentration. Further, high-resolution P/Ca records in multiple colonies of Pavona gigantea and Porites lobata corals grown at the same upwelling location in the Gulf of Panama were strongly correlated to a contemporaneous time-series record of surface water PO4 SW at this site (r2 = 0.7–0.9). This study supports application of the following multi-colony calibration equations to down-core records from comparable upwelling sites, resulting in ±0.2 and ±0.1 lmol/kg uncertainties in PO4 SW reconstructions from P. lobata and P. gigantea, respectively.P/Ca Porites lobata (lmol/mol) = (21.1 ? 2.4)PO4 SW (lmol/kg) + (14.3 ? 3.8)P/Ca Pavona gigantea (lmol/mol) = (29.2 ? 1.4)PO4 SW (lmol/kg) + (33.4 ? 2.7)Inter-colony agreement in P/Ca response to PO4 SW was good (±5–12% about mean calibration slope), suggesting that species-specific calibration slopes can be applied to new coral P/Ca records to reconstruct past changes in surface ocean phosphate. However, offsets in the y-intercepts of calibration regressions among co-located individuals and taxa suggest that biologically-regulated “vital effects” and/or skeletal extension rate may also affect skeletal P incorporation. Quantification of the effect of skeletal extension rate on P/Ca could lead to corrected calibration equations and improved inter-colony P/Ca agreement. Nevertheless, the efficacy of the P/Ca proxy is thus supported by both broad scale correlation to mean surface water phosphate and regional calibration against documented local seawater phosphate variations

Accuracy and reproducibility of coral Sr/Ca SIMS timeseries in modern and fossil corals

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Sayani, H., Cobb, K., Monteleone, B., & Bridges, H. Accuracy and reproducibility of coral Sr/Ca SIMS timeseries in modern and fossil corals. Geochemistry, Geophysics, Geosystems, 23(9), (2022): e2021GC010068, https://doi.org/10.1029/2021gc010068.Coral strontium-to-calcium ratios (Sr/Ca) provide quantitative estimates of past sea surface temperatures (SST) that allow for the reconstruction of changes in the mean state and climate variations, such as the El Nino-Southern Oscillation, through time. However, coral Sr/Ca ratios are highly susceptible to diagenesis, which can impart artifacts of 1–2°C that are typically on par with the tropical climate signals of interest. Microscale sampling via Secondary Ion Mass Spectrometry (SIMS) for the sampling of primary skeletal material in altered fossil corals, providing much-needed checks on fossil coral Sr/Ca-based paleotemperature estimates. In this study, we employ a set modern and fossil corals from Palmyra Atoll, in the central tropical Pacific, to quantify the accuracy and reproducibility of SIMS Sr/Ca analyses relative to bulk Sr/Ca analyses. In three overlapping modern coral samples, we reproduce bulk Sr/Ca estimates within ±0.3% (1σ). We demonstrate high fidelity between 3-month smoothed SIMS coral Sr/Ca timeseries and SST (R = −0.5 to −0.8; p < 0.5). For lightly-altered sections of a young fossil coral from the early-20th century, SIMS Sr/Ca timeseries reproduce bulk Sr/Ca timeseries, in line with our results from modern corals. Across a moderately-altered section of the same fossil coral, where diagenesis yields bulk Sr/Ca estimates that are 0.6 mmol too high (roughly equivalent to −6°C artifacts in SST), SIMS Sr/Ca timeseries track instrumental SST timeseries. We conclude that 3–4 SIMS analyses per month of coral growth can provide a much-needed quantitative check on the accuracy of fossil coral Sr/Ca-derived estimates of paleotemperature, even in moderately altered samples.We'd also like to thank Yolande Berta and Georgia Tech's Center for Nanostructure Characterization for providing access to their SEM facilities, and the Khaled bin Sultan Living Ocean Foundation and The Nature Conservancy for financial and logistical support for field excursions to Palmyra. Funding for this work was provided by the National Science Foundation (Award Numbers 1502832 and 2002458 to K.M.C) and the National Oceanic and Atmospheric Administration (Award Number: NA11OAR4310165 to K.M.C)

Constraints on the salinity–oxygen isotope relationship in the central tropical Pacific Ocean

Uncertainties surround the relationship between salinity and the stable isotopic composition of seawater, largely due to a dearth of modern seawater isotope data. Here we report 191 new, paired measurements of salinity and seawater oxygen isotopes (δ¹⁸O_sw) taken from the central tropical Pacific in May 2012, from the surface to 4600 m depth. We observe significant correlations between δ¹⁸O_sw and salinity across the study region, with slopes ranging from 0.23 to 0.31‰/psu for the mixed layer, and 0.35–0.42‰/psu for waters between the mixed layer and 500 m depth. When considering δ¹⁸O_sw–salinity across averages of individual water masses in the region, slopes range from 0.21 to 0.40‰/psu, albeit with appreciable scatter. Surface salinity and δ¹⁸O_sw data corresponding to the North Equatorial Countercurrent are significantly higher than previously observed, which we attribute to a weak westerly current and dry conditions in the region during the May 2012 cruise. Subsurface (80–500 m) salinity values from 2012 are significantly lower than corresponding values from pre-existing regional data, highlighting a different latitudinal sampling distribution, while subsurface δ¹⁸O_sw is not significantly different. Thus, in May 2012, δ¹⁸O_sw in this region could not be used to distinguish between subsurface water masses of different salinities. Unlike other regions where the surface ‘freshwater endmember’ is close to the δ¹⁸O value of regional precipitation, the freshwater endmember implied by our dataset (− 10.38‰) is consistent with a strong evaporative influence. Paired δ¹⁸O–δD values of precipitation and surface seawaters have similar slopes (5.0, 5.1), and relatively low intercepts (1.4, 0.8) indicating isotopic variability in both reservoirs is also partly controlled by evaporation

Consumers’ Choice of Dentists: How and Why People Choose Dental School Faculty Members as Their Oral Health Care Providers

This study aimed to better understand how and why people choose dental school faculty members as their oral health care providers. Increasing financial constraints in U.S. dental schools have led their administrators to seek alternative funding sources, one of which can be revenues from dental school faculty practice. To effectively promote faculty practice, it is necessary to understand how and why one chooses a dental school faculty member as his or her oral health care provider. A survey of 1,150 dental school faculty practice patients who recently chose their dentist was conducted, and 221 responded. The information sources these respondents said they used and rated highly were other dentists, friends, family members, clinic website, the Internet, and the insurance directory. Dentist-related attributes that were perceived to be important were quality of care, professional competence of dentist, and explanation of treatment/patient participation in the treatment decision. Dental practice-related attributes perceived to be important were the ability to get appointments at convenient times, reasonable waiting time to get appointments, and attitude/helpfulness of staff. This study found that traditionally popular (family, friends) and newly emerging information sources (the Internet, clinic website, and insurance directory) were both used and perceived to be important by patients of the dental school faculty practice. Dental schools and dentists can use this study’s findings to select appropriate communication channels to promote their practices and to focus on attributes that dental consumers value the most

Borneo stalagmite evidence of significantly reduced El Niño-Southern Oscillation variability at 4.1 kyBP

The timing and geographic extent of a potential “4.2 ky event” remain highly contested. Here we present records of ENSO variability at 3.8 kyBP and 4.1 kyBP derived from a Borneo stalagmite, which suggest a significant change in ENSO properties between these time intervals. The Borneo records show evidence of significantly reduced ENSO activity at 4.1 kyBP, relative to other measured windows within the Holocene. This reduced ENSO activity coincides with a period of drier conditions and enhanced dust events in the Middle East that took place ∼4.0–4.3 kyBP. The Borneo records show evidence of enhanced ENSO activity at 3.8 kyBP. Various hydroclimate changes attributed to the “4.2 ky event” in many regions may thus be reflecting a shift from reduced to enhanced El Niño activity that occurred between 3.8 kyBP to 4.0 kyBP

Varied Response of Western Pacific Hydrology to Climate Forcings over the Last Glacial Period

Atmospheric deep convection in the west Pacific plays a key role in the global heat and moisture budgets, yet its response to orbital and abrupt climate change events is poorly resolved. Here, we present four absolutely dated, overlapping stalagmite oxygen isotopic records from northern Borneo that span most of the last glacial cycle. The records suggest that northern Borneo’s hydroclimate shifted in phase with precessional forcing but was only weakly affected by glacial-interglacial changes in global climate boundary conditions. Regional convection likely decreased during Heinrich events, but other Northern Hemisphere abrupt climate change events are notably absent. The new records suggest that the deep tropical Pacific hydroclimate variability may have played an important role in shaping the global response to the largest abrupt climate change events

Extended Cave Drip Water Time Series Captures the 2015–2016 El Niño in Northern Borneo

Time series of cave drip water oxygen isotopes (δ18O) provide site‐specific assessments of the contributions of climate and karst processes to stalagmite δ18O records employed for hydroclimate reconstructions. We present ~12‐year‐long time series of biweekly cave drip water δ18O variations from three sites as well as a daily resolved local rainfall δ18O record from Gunung Mulu National Park in northern Borneo. Drip water δ18O variations closely match rainfall δ18O variations averaged over the preceding 3–18 months. We observe coherent interannual drip water δ18O variability of ~3‰ to 5‰ related to the El Niño–Southern Oscillation (ENSO), with sustained positive rainfall and drip water δ18O anomalies observed during the 2015/2016 El Niño. Evidence of nonlinear behavior at one of three drip water monitoring sites implies a time‐varying contribution from a longer‐term reservoir. Our results suggest that well‐replicated, high‐resolution stalagmite δ18O reconstructions from Mulu could characterize past ENSO‐related variability in regional hydroclimate.Plain Language SummaryCave stalagmites allow for the reconstruction of past regional rainfall variability over the last hundreds of thousands of years with robust age control. Such reconstructions rely on the fact that differences in the isotopic composition of rainwater set by regional rainfall patterns is preserved as the rainwater travels through cave bedrock to feed the cave drip waters forming stalagmites. Long‐term monitoring of rainwater and cave drip water isotopes ground truth the climate to stalagmite relationship across modern‐day changes in regional rainfall. Twelve years of monitoring data presented in this study identify individual El Niño–Southern Oscillation events in rainfall and cave drip water isotopic composition, providing a strong foundation for stalagmite‐based climate reconstructions from this site.Key PointsThree 12‐year‐long cave drip water δ18O time series capture El Niño and La Niña events in northern BorneoEstimates of karst residence times range from 3 to 18 months, with a secondary contribution from a longer‐term reservoir at one drip siteDrip water nonstationarity implies multiple stalagmites are required to reconstruct El Niño–Southern Oscillation variability over timePeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154266/1/grl60264-sup-0002-2019GL086363-SI.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154266/2/grl60264_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154266/3/grl60264.pd

A cross validation of Consumer-Based Brand Equity (CBBE) with Private Labels in Spain

Molinillo,S., Ekinci, Y., Japutra, A. (2014)'A cross validation of Consumer-Based Brand Equity (CBBE) with Private Labels in Spain'. in Martínez-López, Gázquez-Abad, J.C. and Sethuraman, R. J.A. (eds.) Advances in National Brand and Private Label Marketing. Second International Conference, 2015. Springer Proceedings in Business and Economics, pp. 113-125In recent years a number of Consumer-Based Brand Equity (CBBE) models and measurement scales have been introduced in the branding literature. However, examinations of brand equity in Private Labels (PL) are rather limited. This study aims to compare the validity of the two prominent CBBE models those introduced by Yoo and Donthu (2001) and Nam et al. (2011). In order to test the models and make this comparison, the study collected data from 236 respondents who rated private labels in Spain. A list of 30 different fashion and sportswear PL was introduced to respondents. These brands do not make any reference to the retail store in which they are sold. Research findings suggest that the extended CBBE model introduced by Nam et al. (2011) and Ciftci et al. (2014) is more reliable and valid than Yoo and Donthu’s model for assessing PL. Theoretical contributions and managerial implications are discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech