Responses of phytoplankton assemblages to iron availability and mixing water masses during the spring bloom in the Oyashio region, NW Pacific

Authors

T. Isada, Hokkaido University
A. Hattori-Saito, Hokkaido University
H. Saito, Tohoku National Fisheries Research Institute, FRA
Y. Kondo, Graduate School of Agricultural and Life Sciences The University of Tokyo
J. Nishioka, Hokkaido University
K. Kuma, Hokkaido University
H. Hattori, Tokai University
R. M.L. McKay, Bowling Green State University
K. Suzuki, Hokkaido University

Document Type

Article

Publication Date

1-1-2019

Publication Title

Limnology and Oceanography

Volume

64

Issue

1

First Page

197

Last Page

216

Abstract

Spring phytoplankton blooms play a major role in the carbon biogeochemical cycle of the Oyashio region, western subarctic Pacific, where the seasonal biological drawdown effect on seawater pCO 2 is one of the greatest among the world's oceans. However, the bloom often terminates before depleting macronutrients, and the initiation and magnitude of the bloom is heterogeneous. We conducted a high resolution taxonomic and physiological assessment of phytoplankton in relation to the different physicochemical water masses of Coastal Oyashio Water (COW), Oyashio water (OYW), and modified Kuroshio water (MKW) in the Oyashio region from April to June 2007. Massive diatom blooms were found in April. Then, chlorophyll a concentration, cell abundance of diatom taxa, and the maximum photosystem II photochemical efficiency (F v /F m ) were positively correlated with the mixing ratios of COW, suggesting that the spring bloom in April was strongly affected by the intrusion of COW. In the OYW, intensive blooms occurred from the middle of May under low dissolved iron (DFe) concentration (< 0.26 nM). Redundancy analysis showed that while diatom blooms accompanied by COW were related to DFe concentration, this was not the case in the OYW. These results indicated that diatoms in the OYW possess different iron adaptation strategies compared with diatoms in the water masses affected by COW. This led to the spatial heterogeneity of the Oyashio spring bloom. The results presented here demonstrate that water mass characterization with detailed assessments of phytoplankton taxonomy and physiological status can improve our understanding of marine ecosystems.

DOI

10.1002/lno.11031

E-ISSN

19395590

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Isada, T.; Hattori-Saito, A.; Saito, H.; Kondo, Y.; Nishioka, J.; Kuma, K.; Hattori, H.; McKay, R. M.L.; and Suzuki, K.. (2019). Responses of phytoplankton assemblages to iron availability and mixing water masses during the spring bloom in the Oyashio region, NW Pacific. Limnology and Oceanography, 64 (1), 197-216.
https://scholar.uwindsor.ca/glierpub/554