Isoscape Models of the Southern Ocean: Predicting Spatial and Temporal Variability in Carbon and Nitrogen Isotope Compositions of Particulate Organic Matter

Type Article
Date 2021-09
Language English
Author(s) St John Glew Katie1, Espinasse BorisORCID2, Hunt Brian P. V.ORCID3, 4, 5, Pakhomov Evgeny A.3, 4, 5, Bury Sarah J.6, Pinkerton Matt6, Nodder Scott D.6, Gutiérrez‐rodríguez AndresORCID6, Safi Karl7, Brown Julie C. S.6, Graham LauraORCID8, 9, Dunbar Robert B.ORCID10, Mucciarone David A.10, Magozzi Sarah11, Somes ChrisORCID12, Trueman Clive N.1, 13
Affiliation(s) 1 : School of Ocean and Earth Science,University of Southampton National Oceanography Centre Southampton Southampton, UK
2 : Department of Arctic and Marine Biology ,UiT The Arctic University of Norway Tromsø ,Norway
3 : Institute for the Oceans and Fisheries, University of British Columbia Vancouver BC ,Canada
4 : Department of Earth, Ocean and Atmospheric Sciences University of British Columbia Vancouver BC ,Canada
5 : Hakai Institute Tula Foundation Heriot Bay BC, Canada
6 : National Institute of Water & Atmospheric Research Ltd (NIWA) ,Wellington, New Zealand
7 : National Institute of Water & Atmospheric Research Ltd (NIWA),Hamilton ,New Zealand
8 : Geography, Earth and Environmental Sciences University of Birmingham Birmingham, UK
9 : Biodiversity, Ecology and Conservation Group International Institute for Applied Systems Analysis Laxenburg ,Austria
10 : Earth System Science ,Stanford University Stanford CA, USA
11 : Department of Integrative Marine Ecology ,Stazione Zoologica Anton Dohrn Fano Marine Centre Fano ,Italy
12 : Marine Biogeochemical Modelling, GEOMAR Helmholtz Centre for Ocean Research Kiel Kiel, Germany
13 : Hong Kong Branch of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) Hong Kong ,China
Source Global Biogeochemical Cycles (0886-6236) (American Geophysical Union (AGU)), 2021-09 , Vol. 35 , N. 9 , P. e2020GB006901 (18p.)
DOI 10.1029/2020GB006901
WOS© Times Cited 11
Keyword(s) stable isotopes, delta C-13 and delta N-15, POM, Bayesian spatial modeling, migration pathways, trophic baseline

Polar marine ecosystems are particularly vulnerable to the effects of climate change. Warming temperatures, freshening seawater, and disruption to sea-ice formation potentially all have cascading effects on food webs. New approaches are needed to better understand spatiotemporal interactions among biogeochemical processes at the base of Southern Ocean food webs. In marine systems, isoscapes (models of the spatial variation in the stable isotopic composition) of carbon and nitrogen have proven useful in identifying spatial variation in a range of biogeochemical processes, such as nutrient utilization by phytoplankton. Isoscapes provide a baseline for interpreting stable isotope compositions of higher trophic level animals in movement, migration, and diet research. Here, we produce carbon and nitrogen isoscapes across the entire Southern Ocean (>40°S) using surface particulate organic matter isotope data, collected over the past 50 years. We use Integrated Nested Laplace Approximation-based approaches to predict mean annual isoscapes and four seasonal isoscapes using a suite of environmental data as predictor variables. Clear spatial gradients in δ13C and δ15N values were predicted across the Southern Ocean, consistent with previous statistical and mechanistic views of isotopic variability in this region. We identify strong seasonal variability in both carbon and nitrogen isoscapes, with key implications for the use of static or annual average isoscape baselines in animal studies attempting to document seasonal migratory or foraging behaviors.

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St John Glew Katie, Espinasse Boris, Hunt Brian P. V., Pakhomov Evgeny A., Bury Sarah J., Pinkerton Matt, Nodder Scott D., Gutiérrez‐rodríguez Andres, Safi Karl, Brown Julie C. S., Graham Laura, Dunbar Robert B., Mucciarone David A., Magozzi Sarah, Somes Chris, Trueman Clive N. (2021). Isoscape Models of the Southern Ocean: Predicting Spatial and Temporal Variability in Carbon and Nitrogen Isotope Compositions of Particulate Organic Matter. Global Biogeochemical Cycles, 35(9), e2020GB006901 (18p.). Publisher's official version : , Open Access version :