ENVIRONMENTAL DRIVERS OF MESOZOOPLANKTON BIOMASS VARIBILITY AT STATION ALOHA, NORTH PACIFIC SUBTROPICAL GYRE (E)
We explored the environmental drivers of zooplankton variability at Station ALOHA in the central subtropical Pacific, where mesozooplankton biomass has increased 193% from 1994 (650 ± 240 mg DW m-2) to 2015 (1250 ± 290 mg DW m-2). The increase was significant earlier in the time series, but biomass has remained relatively constant since 2004. Based on analyses by Generalized Additive Models (GAM), monthly mean variability in zooplankton biomass is significantly influenced by primary productivity (PP), sea surface temperature (SST), North Pacific Gyre Oscillation (NPGO), and El Niño (GAM: 43%). This result mainly reflects the seasonal plankton cycle at Stn. ALOHA in which increasing light and SST lead to enhanced nitrogen fixation, productivity, and zooplankton biomass during summertime. Variability of annual mean zooplankton biomass is significantly influenced by PP, 4-year lagged NPGO, and 4-year lagged Pacific Decadal Oscillation (GAM: 70%). Our study highlights a strong coupling between zooplankton fluctuations and PP, which differs from the transport-dominated climate influences found for zooplankton in North Pacific boundary currents. Despite the interannual variability in PP and total zooplankton biomass at Stn. ALOHA, zooplankton size distribution has remained relatively uniform, except for an increase in smaller animals during 1998-99, a likely influence of the strong 1997-98 El Niño.
Valencia, B., Scripps Institution of Oceanography, University of California San Diego, USA, email@example.com
Landry, M. R., Scripps Institution of Oceanography, University of California San Diego, USA, firstname.lastname@example.org
Décima, M., National Institute of Water and Atmospheric Research, NIWA, New Zealand, Moira.Decima@niwa.co.nz
Hannides, C. C., Department of Geology and Geophysics, University of Hawaii, email@example.com
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