Primary Productivity Dynamics in the Summer Arctic Ocean Confirms Broad Regulation of the Electron Requirement for Carbon Fixation by Light-Phytoplankton Community Interaction

Zhu, Yuanli; Suggett, David J.; Liu, Chenggang; He, Jianfeng; Lin, Longshan; Le, Fengfeng; Ishizaka, Joji; Goés, Joaquim I.; Hao, Qiang

doi:10.3389/fmars.2019.00275

Cited by 12 publications

(18 citation statements)

References 99 publications

(190 reference statements)

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“…Moreover, compared with the theoretical maximum value (0.65) determined by Kolber and Falkowski (1993), approximately 40% of the PSII reaction centers appear to have been inactive. Zhu et al (2019) also reported that the F v / F m in the Chukchi Borderland was approximately 24% lower than in the CS waters, which was similar to the results of this study. Meanwhile, the F v / F m observed off the coast of the Arctic Ocean is known to remain high (≥0.50) throughout the year, except immediately after the spring bloom (Aardema et al, 2019; Kulk et al, 2018; McMinn & Hegseth, 2004; Mills et al, 2018; Mosharov et al, 2019).…”

Section: Discussionsupporting

confidence: 91%

“…Moreover, nutrient uptake rates and carbon‐specific photosynthesis vary with changes in the phytoplankton community structure (Cermeño et al, 2005; Hein et al, 1995; Uitz et al, 2008). Recently, the physiological status of phytoplankton in the Arctic Ocean was also known to be affected by light availability and phytoplankton community structure under nitrogen limitation (Kulk et al, 2018; Mills et al, 2018; Mosharov et al, 2019; Zhu et al, 2019). However, these studies were result of a year limited to coastal and shelf regions of the Arctic Ocean, and lacked experimental information on the extent to which physiological conditions were reduced by nitrogen limitation.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Nitrogen Limitation on Phytoplankton Physiology in the Western Arctic Ocean in Summer

Gorbunov

Jung

et al. 2020

JGR Oceans

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Phytoplankton in the Arctic Ocean are subject to nitrogen limitation in the summer, however, how severely the nitrogen stress affects phytoplankton physiology remains largely unknown. In the summers of 2015-2018, we examined the distribution of phytoplankton photophysiological properties across two contrasting regions of the Arctic Ocean with distinctly different levels of nitrogen availability in the upper water column. We quantified the extent of nitrogen stress using a highly sensitive fluorescence induction and relaxation system to obtain continuous underway measurements and via discrete sample analyses of phytoplankton physiology, as well as nutrient enrichment incubations. The results revealed vast regions in the Chukchi Sea where phytoplankton photosynthesis was severely nitrogen-stressed. Thereby, the maximum quantum yield of photochemistry in photosystem II showed only a small decrease (12 ± 9%) relative to its nutrient-replete values, while the maximum photosynthetic electron transport rates under saturating irradiance were impaired to a greater extent (40 ± 17%). This phytoplankton photosynthesis response is indicative of a severe nitrogen limitation, which results in dramatic reduction in growth and net primary production rates. Nutrient enrichment incubations also revealed a marked increase in large-size phytoplankton growth (>10 μm) after the nitrogen stress was alleviated, suggesting that the larger cells were more susceptible to nitrogen stress. These results are important for understanding how regional nitrogen fluxes control variability in the primary production and phytoplankton community structure and how these processes might change with rapid climate changes in the Arctic Ocean. Plain Language Summary Nutrient availability is the main bottom-up controls of phytoplankton physiology and growth in the upper ocean. The distribution of nutrient limitation in the global ocean varies greatly in space and time, so phytoplankton responses to this factor are essential for understanding the marine ecosystem. Although nitrogen limitation was previously shown in the Arctic Ocean in the summer, how nitrogen stress affects phytoplankton physiology remains largely unknown. This study investigates, with high spatial resolution, the distribution of phytoplankton physiological status and quantifies the effects of nitrogen stress in the western Arctic Ocean. Our results revealed severe nitrogen limitation in the summer that results in dramatic reduction in growth and net primary production in this region of the ocean. Therefore, alterations in nitrogen fluxes along with climate change in the Arctic Ocean would be important for controlling phytoplankton growth and primary production in this region.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Effects of Nitrogen Limitation on Phytoplankton Physiology in the Western Arctic Ocean in Summer

Gorbunov

Jung

et al. 2020

JGR Oceans

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“…Typically, variability in irradiance level was another primary driver of variability in F v /F m , F q /F m , and F q /F v in the WPO (p < 0.05; Figure 7). The depth-specific fitting values of these light absorption characteristics we observed were higher at the subsurface (Figure 4), and one important explanation for this is that the interactive effects of light and nutrient levels lead to an increase in these light absorption parameters (Moore et al, 2006;Suggett et al, 2009;Zhu et al, 2019). In contrast, the strong effects of excess irradiance pressure and limitation by nutrients in the surface inhibited the F v /F m , F q /F m , and F q /F v (Figure 4; Schuback et al, 2017;Wei et al, 2019b).…”

Section: Physiological and Ecological Responses Of Photosynthetic Promentioning

confidence: 75%

“…While our dataset is too small to draw general conclusions, our experimental results allow us to gain some physiological and ecological insights into how the dominant environmental constraints and algal species regulate the light absorption characteristics and electron transport and what is the key in driving the dynamics of WPO primary productivity. Light absorption parameters F v /F m and F q /F m showed positive correlations with size-fractionated Chl a (p < 0.01; Figure 7), suggesting that the light absorption characteristics in photosynthetic process are potentially controlled by the variability in phytoplankton communities (Suggett et al, 2009;Schuback et al, 2017;Zhu et al, 2019;Wei et al, 2019b). Certainly, this result appears to be exemplified to differing degrees by the significant relationships between F v /F m and large diatoms (cells > 2 µm), picosized Pro and PEuks (see Figure 8A below).…”

Section: Physiological and Ecological Responses Of Photosynthetic Promentioning

confidence: 99%

“…Thereafter, the ecologically relevant rates of carbon fixation can be converted by FRRF-derived ETR RCII through a conversion factor, i.e., the effective electron requirement for carbon fixation ( Melrose et al, 2006 ; Zhu et al, 2016 ; Schuback et al, 2017 ; Morelle and Claquin, 2018 ). Additionally, the applicability of FRRF-based measurements to estimate marine primary production, alone or in combination with other techniques, are potentially limited since the light absorption characteristics and electron transport vary significantly in response to environmental constraints or combinations thereof and changes in species taxonomy and physiology ( Lawrenz et al, 2013 ; Jin et al, 2016 ; Schuback et al, 2017 ; Xie et al, 2018 ; Wei et al, 2019b ; Zhu et al, 2019 ). As such, more recent studies have sought to better characterize the extent and nature of variation between these photosynthetic processes and environmental/biological variables ( Moore et al, 2003 ; Suggett et al, 2009 ; Schuback et al, 2017 , etc.).…”

Section: Introductionmentioning

confidence: 99%

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Physiological and Ecological Responses of Photosynthetic Processes to Oceanic Properties and Phytoplankton Communities in the Oligotrophic Western Pacific Ocean

et al. 2020

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Understanding the dynamics of primary productivity in a rapidly changing marine environment requires mechanistic insight into the photosynthetic processes (light absorption characteristics and electron transport) in response to the variability of environmental conditions and algal species. Here, we examined the photosynthetic performance and related physiological and ecological responses to oceanic properties [temperature, salinity, light, size-fractionated chlorophyll a (Chl a) and nutrients] and phytoplankton communities in the oligotrophic Western Pacific Ocean (WPO). Our results revealed high variability in the maximum (F v /F m ; 0.08-0.26) and effective (F q /F m ; 0.02-0.22) photochemical efficiency, the efficiency of charge separation (F q /F v ; 0.19-1.06), the photosynthetic electron transfer rates (ETR RCII ; 0.02-5.89 mol e − mol RCII −1 s −1) and the maximum of primary production [PP max ; 0.04-8.59 mg C (mg chl a) −1 h −1 ]. All these photosynthetic characteristics showed a depth-specific dependency based on respective nonlinear regression models. On physiological scales, variability in light absorption parameters F v /F m and F q /F m notably correlated with light availability and size-fractionated Chl a, while both ETR RCII and PP max were correlated to temperature, light, and ambient nutrient concentration. Since the presence of nonphotochemical quenching (NPQ NSV ; 2.33-12.31) and increasing reductant are used for functions other than carbon fixation, we observed nonparallel changes in the ETR RCII and F v /F m , F q /F m , F q /F v. In addition, we found that the important biotic variables influencing F v /F m were diatoms (cells > 2 µm), picosized Prochlorococcus, and eukaryotes, but the PP max was closely related to large cyanobacteria (cells > 2 µm), dinoflagellates, and picosized Synechococcus. The implication is that, on ecological scales, an interaction among temperature, light, and nutrient availability may be key in driving the dynamics of primary productivity in the WPO, while large cyanobacteria, dinoflagellates, and picosized Synechococcus may have a high contribution to the primary production. Overall, the photosynthetic processes are interactively affected by complex abiotic and biotic variables in marine ecosystems, rather than by a single variable.

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Algal Bloom, Succession, and Drawdown of Silicate in the Chukchi Sea in Summer 2010

et al. 2021

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Primary Productivity Dynamics in the Summer Arctic Ocean Confirms Broad Regulation of the Electron Requirement for Carbon Fixation by Light-Phytoplankton Community Interaction

Cited by 12 publications

References 99 publications

Effects of Nitrogen Limitation on Phytoplankton Physiology in the Western Arctic Ocean in Summer

Effects of Nitrogen Limitation on Phytoplankton Physiology in the Western Arctic Ocean in Summer

Physiological and Ecological Responses of Photosynthetic Processes to Oceanic Properties and Phytoplankton Communities in the Oligotrophic Western Pacific Ocean

Algal Bloom, Succession, and Drawdown of Silicate in the Chukchi Sea in Summer 2010

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