Diatom Community Response to High and Low Iron Upwelling Plumes in the California Current System

Authors

Sveinn V. Einarsson, Old Dominion UniversityFollow
Kimberly Powell, Old Dominion UniversityFollow
Claire Till, California State Polytechnic University - Humboldt
Tyler Coale, University of California Santa Cruz
P. Dreux Chappell, Old Dominion University

ORCID

0009-0000-7468-4343 (Powell), 0000-0001-5212-6228 (Chappell)

Document Type

Article

Publication Date

2026

DOI

10.1016/j.pocean.2026.103703

Publication Title

Progress in Oceanography

Volume

243

Pages

103703

Abstract

Diatoms are important primary producers, accounting for most of the oceanic production and carbon export relative to other photosynthetic eukaryotes. There are important differences among diatom species that enable them to proliferate in different environments. Some have nutrient storage capabilities or lower nutrient quotas suited for oligotrophic oceans. Bloom-forming diatoms are typically found in nutrient-rich coastal waters where they respond quickly to nutrient pulses and can influence biogeochemical cycling in the ocean after blooms. As many physiological differences affect biomass and export, it is important to better understand how physical and chemical parameters influence diatom community composition, especially in dynamic upwelling environments. Examining diatom community responses to upwelling can be challenging, as it is difficult to capture and track upwelling waters from initiation. Here, we present the diatom community composition from two physically and chemically distinct upwelling plumes in the California Current System (CCS), determined using 18S rDNA sequencing, to test the hypothesis that iron (Fe) influences upwelling diatom communities. Diatom community composition, dFe, and dFe:nitrate (NO₃^–) were all significantly different in the two upwelling plumes. There was higher fluorescence and higher relative abundance of bloom-forming Chaetoceros at the start of the upwelling transect with higher initial dFe. Interestingly, the complex physics of the CCS appeared to influence the dispersion of upwelling-induced diatom communities, with the same Chaetoceros species abundant after passing through a high velocity jet in the lower initial dFe upwelling transect. We conclude with a discussion of possible implications for future predictions of diatom proliferation, transport, and carbon export in the CCS.

Rights

© 2026 The Authors.

This is an open access article under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC-BY-NC-ND 4.0) License.

Data Availability

Article states: "All data is in public databases (see data availability statement). Code for analysis is available on request.

The raw sequence data is available on NCBI SRA under BioProject Accession PRJNA1071667. The trace metals and macronutrients are available on BCO-DMO (https://www.bco-dmo.org/dataset/943015)."

Original Publication Citation

Einarsson, S. V., Powell, K., Till, C., Coale, T., & Chappell, P. D. (2026). Diatom community response to high and low iron upwelling plumes in the California Current System. Progress in Oceanography, 243, Article 103703. https://doi.org/10.1016/j.pocean.2026.103703

Repository Citation

Einarsson, Sveinn V.; Powell, Kimberly; Till, Claire; Coale, Tyler; and Chappell, P. Dreux, "Diatom Community Response to High and Low Iron Upwelling Plumes in the California Current System" (2026). OES Faculty Publications. 568.
https://digitalcommons.odu.edu/oeas_fac_pubs/568