Influência da variabilidade ambiental e ecotipos emiliania huxleyi em reconstruções de temperatura derivadas de alkenona no oceano sul subantártico
| Autor: | Rigual-Hernández, A.S., Sierro, F.J., Flores, J.A., Trull, T.W., Rodrigues, T., Martrat, B., Sikes, E.L., Nodder, S.D., Eriksen, R.S., Davies, D., Bravo, N., Sánchez-Santos, J.M., Abrantes, F. |
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| Přispěvatelé: | Ministerio de Ciencia e Innovación (España) |
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: |
Ecotype
Environmental Engineering Oceans and Seas Armadilha de sedimentos de partículas Temperature Gephyrocapsa-oceanica Haptophyta Estimativa de paleotemperatura Calópico-de-Nannoplkton Pelotas fecais Zooplâncton Emiliania huxleyi Zonas frontais polares Pollution Alkenones de cadeia longa Environmental Chemistry Neve marinha Southern Ocean Waste Management and Disposal |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | Long-chain unsaturated alkenones produced by haptophyte algae are widely used as paleotemperature indicators. The unsaturation relationship to temperature is linear at mid-latitudes, however, non-linear responses detected in subpolar regions of both hemispheres have suggested complicating factors in these environments. To assess the influence of biotic and abiotic factors in alkenone production and preservation in the Subantarctic Zone, alkenone fluxes were quantified in three vertically-moored sediment traps deployed at the SOTS observatory (140°E, 47°S) during a year. Alkenone fluxes were compared with coccolithophore assemblages, satellite measurements and surface-water properties obtained by sensors at SOTS. Alkenone-based temperature reconstructions generally mirrored the seasonal variations of SSTs, except for late winter when significant deviations were observed (3-10 °C). Annual flux-weighted averages in the 3800 m trap returned alkenone-derived temperatures ~1.5 °C warmer than those derived from the 1000 m trap, a distortion attributed to surface production and signal preservation during its transit through the water column. Notably, changes in the relative abundance of E. huxleyi var. huxleyi were positively correlated with temperature deviations between the alkenone-derived temperatures and in situ SSTs (r = 0.6 and 0.7 at 1000 and 2000 m, respectively), while E. huxleyi var. aurorae, displayed an opposite trend. Our results suggest that E. huxleyi var. aurorae produces a higher proportion of C37:3 relative to C37:2 compared to its counterparts. Therefore, the dominance of var. aurorae south of the Subtropical Front could be at least partially responsible for the less accurate alkenone-based SST reconstructions in the Southern Ocean using global calibrations. However, the observed correlations were largely influenced by the samples collected during winter, a period characterized by low particle fluxes and slow sinking rates. Thus, it is likely that other factors such as selective degradation of the most unsaturated alkenones could also account for the deviations of the alkenone paleothermometer. We thank the constructive comments and suggestions of five anonymous reviewers that helped improve and clarify this paper. Cathryn Wynn-Edwards (IMAS) provided support in sample splitting/processing and laboratory analysis. We are grateful to Ivia Closset for helpful comments on interpretation of results and to Erik Behrens for providing data for this research. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement number 748690 – SONAR-CO2. Australia's Integrated Marine Observing System (IMOS) is enabled by the National Collaborative Research Infrastructure Strategy (NCRIS). It is operated by a consortium of institutions as an unincorporated joint venture, with the University of Tasmania as Lead Agent. This study was supported by the Spanish Ministerio de Economía y Competitividad Project CGL2015-68459-P. The Severo Ochoa Grant CEX2018-000794-S funded by MCIN/AEI/10.13039/501100011033 is likewise acknowledged. This study received Portuguese national funds from FCT - Foundation for Science and Technology through project UIDB/04326/2020, and from the operational programmes CRESC Algarve 2020 and COMPETE 2020 through projects EMBRC.PT ALG-01-0145-FEDER-022121 and EMSO-PT POCI-01-0145-FEDER-022157. Argo data were collected and made freely available by the International Argo Program and the national programmes that contribute to it. (http://www.argo.ucsd.edu, http://argo.jcommops.org). The Argo Program is part of the Global Ocean Observing System. Satellite SST, chlorophyll-a and coccolithophore concentration (NOBM) data sets were produced with the Giovanni online data system, developed and maintained by the NASA GES DISC. |
| Databáze: | OpenAIRE |
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