Marine Ecology Progress Series | |
Size-dependent photosynthetic variability in the North Pacific Subtropical Gyre | |
Ricardo M. Letelier1  Binglin Li1  Matthew J. Church1  David M. Karl1  | |
关键词: Photosynthesis; Photophysiology; Phytoplankton; Primary production; North Pacific; Oligotrophic; | |
DOI : 10.3354/meps09345 | |
学科分类:海洋学与技术 | |
来源: Inter-Research | |
【 摘 要 】
ABSTRACT: Photosynthesis-irradiance (P-E) relationships and in situ measurements of primary production for 2 phytoplankton size fractions (>2 µm and 0.2 to 2 µm) were used to evaluate variability in photophysiology over a 5 yr period (2004 to 2009) in the North Pacific Subtropical Gyre (NPSG). Picophytoplankton (0.2 to 2 µm) were dominant contributors to euphotic zone chlorophyll a (chl a) concentrations (averaging 91 ± 2% [mean ± SD] of the 0 to 125 m depth-integrated inventories) and accounted for a major fraction (averaging 74 ± 7%) of the in situ, depth-integrated, 14C-based primary production. Short-term in vitro P-E experiments were conducted to examine the photophysiology of both phytoplankton size classes. Results from these experiments demonstrated that in the well-lit ocean (0 to 45 m) chl a normalized maximum rates of photosynthesis, Pchlmax, were significantly greater among the larger phytoplankton size class than in the smaller size fraction (1-way ANOVA, p < 0.01), while in the dimly lit region (125 m) there were no significant size-dependent differences in Pchlmax (1-way ANOVA, p > 0.05). Neither the initial slope of the P-E relationships, α, nor the light intensities required to saturate photosynthesis, Ek, varied significantly between the 2 size fractions. Although larger phytoplankton appear to constitute a relatively small fraction of phytoplankton biomass and production in this ecosystem, the photophysiological responses of plankton in this size class demonstrated considerable variability, suggesting these larger size phytoplankton experience time-variable changes in growth despite persistently oligotrophic habitat conditions.
【 授权许可】
Unknown
【 预 览 】
Files | Size | Format | View |
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RO201912010134573ZK.pdf | 754KB | download |