MEPS 568:31-45 (2017)  -  DOI: https://doi.org/10.3354/meps12045

Spatial and temporal variability within marine isoscapes: implications for interpreting stable isotope data from marine systems

Carolyn M. Kurle1,*, Jennifer K. McWhorter2,3

1Division of Biological Sciences, Ecology, Behavior, and Evolution Section, University of California, San Diego, La Jolla, CA 92093, USA
2Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
3Present address: Southern California Coastal Ocean Observing System (SCCOOS), Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
*Corresponding author:

ABSTRACT: Analyses of intrinsic biogeochemical markers, such as stable carbon (δ13C) and nitrogen (δ15N) isotopes, in animal tissues are used to investigate multiple ecological parameters for marine species. Their successful application relies on a mechanistic understanding of isotopic variations at the base of the food web because those variations influence isotope values in higher trophic level species. To better determine the potential for and mechanisms driving spatial and temporal changes in isotope values from an oceanographically complex nearshore marine system, we (1) constructed fine-scale δ13C and δ15N isoscapes of the Southern California Bight (SCB) using isotope values from particulate organic matter (POM) collected over 5 seasons from ~30 stations and (2) related the isotope data to geographic, seasonal, and oceanographic parameters collected from the same stations via a multimodel procedure and regression analyses. Important variables for predicting the δ13C and δ15N values from the POM included chlorophyll a, latitude, and season, and longitude, season, nitrate, and oxygen, respectively. We related these variables to seasonal shifts in nutrients most pronounced around localized eddies that concentrate upwelling. The potential for such variability should be considered when interpreting small-scale geographic and/or seasonal patterns in isotope data from species in the SCB and other dynamic coastal waters. However, the overall isotopic variability for the SCB was relatively low, with mean (±SD) δ13C and δ15N values of -22.7 ± 2.0‰ and 8.0 ± 1.5‰, respectively, allowing for isotopic categorization of the SCB and comparison with other Eastern Pacific coastal areas to better understand larger-scale animal migration patterns, foraging ecology, and habitat use.


KEY WORDS: δ13C · δ15N · Stable isotope analysis · Ecogeochemistry · Foraging ecology · Southern California Bight · California Current · Pacific Ocean


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Cite this article as: Kurle CM, McWhorter JK (2017) Spatial and temporal variability within marine isoscapes: implications for interpreting stable isotope data from marine systems. Mar Ecol Prog Ser 568:31-45. https://doi.org/10.3354/meps12045

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