Environmental drivers of mesozooplankton biomass variability in the North Pacific Subtropical Gyre

TitleEnvironmental drivers of mesozooplankton biomass variability in the North Pacific Subtropical Gyre
Publication TypeJournal Article
Year of Publication2016
AuthorsValencia B., Landry MR, Decima M, Hannides C.CS
JournalJournal of Geophysical Research-Biogeosciences
Date Published2016/12
Type of ArticleArticle
ISBN Number2169-8953
Accession NumberWOS:000393134800016
Keywordscalifornia current; climate-change; cyanobacterium-trichodesmium; long-term changes; marine ecosystems; ocean; phytoplankton; sea; station aloha; Zooplankton

The environmental drivers of zooplankton variability are poorly explored for the central subtropical Pacific, where a direct bottom-up food-web connection is suggested by increasing trends in primary production and mesozooplankton biomass at station ALOHA (A Long-term Oligotrophic Habitat Assessment) over the past 20 years (1994-2013). Here we use generalized additive models (GAMs) to investigate how these trends relate to the major modes of North Pacific climate variability. A GAM based on monthly mean data explains 43% of the temporal variability in mesozooplankton biomass with significant influences from primary productivity (PP), sea surface temperature (SST), North Pacific Gyre Oscillation (NPGO), and El Nino. This result mainly reflects the seasonal plankton cycle at station ALOHA, in which increasing light and SST lead to enhanced nitrogen fixation, productivity, and zooplankton biomass during summertime. Based on annual mean data, GAMs for two variables suggest that PP and 3-4 year lagged NPGO individually account for similar to 40% of zooplankton variability. The full annual mean GAM explains 70% of variability of zooplankton biomass with significant influences from PP, 4 year lagged NPGO, and 4 year lagged Pacific Decadal Oscillation (PDO). The NPGO affects wind stress, sea surface height, and subtropical gyre circulation and has been linked to mideuphotic zone anomalies in salinity and PP at station ALOHA. Our study broadens the known impact of this climate mode on plankton dynamics in the North Pacific. While lagged transport effects are also evident for subtropical waters, our study highlights a strong coupling between zooplankton fluctuations and PP, which differs from the transport-dominated climate influences that have been found for North Pacific boundary currents.

Short TitleJ. Geophys. Res.-Biogeosci.
Student Publication: