Weak Response of Biological Productivity and Community Structure of Phytoplankton to Mesoscale Eddies in the Oligotrophic Philippine Sea

Yun, Mi Sun; Kim, Yejin; Jeong, Yubeen; Joo, Hui Tae; Jo, Young‐Heon; Lee, Chang Hwa; Bae, Hyeonji; Lee, Dabin; Bhavya, P. S.; Kim, Dongseon; Sun, Jun; Lee, Sang H.

doi:10.1029/2020jc016436

Cited by 16 publications

(17 citation statements)

References 67 publications

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“…These are equivalent to 210 and 130 mg C m −2 d −1 , assuming a photosynthetic quotient of 1.4 (Laws, 1991). Given that the typical 18 O-GPP/ 14 C-NPP value range is 2.0-2.7 (Marra, 2002;Quay et al, 2010), these values are consistent with the NPP value of 76-80 mg C m −2 d −1 measured using the 13 C incubation method in the study region in 2018 (Yun et al, 2020).…”

Section: Extreme Oligotrophy Of the Northwest Pacificsupporting

confidence: 77%

Insignificant effects of eddies and typhoons on the biogeochemistry of the tropical northwest Pacific Ocean

et al. 2022

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We investigated the effects of eddies and typhoons on the biogeochemistry of the tropical northwest Pacific by examining the distribution of nutrients, dissolved oxygen (DO), chlorophyll-a (Chl-a), gross primary production (GPP), dissolved organic carbon (DOC), and fluorescent dissolved organic matter (FDOM). Water samples were collected from anticyclonic and cyclonic eddies in September 2019 and 2020, and before and after the passage of a Category 2 typhoon in 2019. The study region was characterized by a deep nitracline (~150 m), which was deeper than both the pycnocline (~50 m) and the FDOM-depleted layer (~75 m). A subsurface chlorophyll maximum layer was observed at 100–150 m depth. No clear differences in Chl-a, DO, GPP, DOC, and FDOM were observed for the anticyclonic and cyclonic eddies, indicating that the eddies did not have a significant influence on biological production. Similarly, there were no discernable changes in Chl-a concentrations or other biogeochemical parameters after the passage of the typhoon, which induced water mixing to a depth of ~60 m. We conjecture that the nutrient-depleted layer was too deep for any eddy- or typhoon-induced vertical mixing to cause upwelling of nutrients to the euphotic zone. Our results imply that the disturbances caused by mesoscale processes in the upper layer of the highly oligotrophic northwest Pacific may have a smaller effect than in oceans in other parts of the world.

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Section: Extreme Oligotrophy Of the Northwest Pacificsupporting

confidence: 77%

Insignificant effects of eddies and typhoons on the biogeochemistry of the tropical northwest Pacific Ocean

et al. 2022

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“…This large difference in primary production may be associated with environmental conditions such as light intensity and nutrients (Pabi et al, 2008;Tremblay et al, 2015;Lee et al, 2019;Zheng et al, 2021). Prior to this study, Yun et al (2020) observed that picophytoplankton, the presence of which indicates a nutrient-deficient state, were the predominant phytoplankton groups despite the occurrence of mesoscale eddies supplying nutrients to the euphotic layer in the Philippine Sea. Our results on the phytoplankton community also indicated that picophytoplankton, containing P r o ch l o r oc oc cu s a n d S y n e c h o c o c c u s , wa s a m a jo r phytoplankton group in the Philippine Sea, suggesting that nutrients were limited at both light depths.…”

Section: Vertical Distribution Characteristics Of Primary Production ...mentioning

confidence: 61%

“…Additionally, Ting et al (2002) described how Prochlorococcus is particularly efficient in absorbing enriched blue light at depth compared with Synechococcus, and this light absorption ability gives Prochlorococcus a competitive advantage under low light conditions. Although nutrients are also an important factor in the survival and competition of phytoplankton, Yun et al (2020) observed a weak impact of nutrient supplies in mesoscale eddies on phytoplankton community composition in the Philippine Sea. This light adaptation in photosynthetic pigments determines the competitive advantages of each phytoplankton group, and it may contribute to the phytoplankton community structure at different depths in oligotrophic oceans.…”

Section: Introductionmentioning

confidence: 95%

Physiological characteristics of phytoplankton in response to different light environments in the Philippine Sea, Northwestern Pacific Ocean

et al. 2022

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The physiological status of phytoplankton, used to determine the quantity and quality of basic food sources in marine ecosystems, can change rapidly due to ambient environmental conditions (e.g., light, temperature, and nutrients). To understand the physiological characteristics of phytoplankton, the phytoplankton community composition, pigment concentration, primary production, and pigment production rate were estimated at 100% and 1% light depths in the Philippine Sea during the summer of 2019. The predominant phytoplankton classes at both light depths were Prochlorococcus and Synechococcus during the study period. Pigment concentrations, except for photoprotective pigment concentrations (i.e., diadinoxanthin and zeaxanthin), were significantly higher (t-test, p<0.05) at 1% light depth to increase the light-harvesting efficiency. The production rates of these pigments had a weak correlation with primary production at 100% light depth, whereas they showed a strong positive relationship at 1% light depth. Moreover, all photosynthetic pigments had a significantly faster turnover rate at 100% light depth compared with 1% light depth to obtain light energy to repair PSII subunits damaged by strong light. This suggests that the phytoplankton community, especially cyanobacteria (Prochlorococcus and Synechococcus), could use light energy absorbed by newly produced photosynthetic pigments for repairing photoinhibition-damaged PSII as well as for production activity. A further study on photosynthetic pigments responding to light conditions must be conducted for a better understanding of the physiological conditions of phytoplankton.

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“…Xu et al (2019) reported that ~5,000 eddies were detected in the NWP over 20 years , with a mean lifespan of ~7 weeks and a mean speed of 6 km d −1 westward. Yun et al (2020) reported no clear differences in phytoplankton biomass and PP between the outer area of the eddies and the mesoscale eddies in the tropical NWP.…”

Section: Introductionmentioning

confidence: 91%

Export of particulate organic carbon (POC) in the eddy region of the tropical northwest Pacific

et al. 2022

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We examined particulate organic carbon (POC) export using 238U–234Th disequilibrium in the tropical northwest Pacific Ocean, where numerous eddies are present. We obtained data from an anticyclonic eddy in 2019 and from both anticyclonic and cyclonic eddies in 2020. In 2019, excess 234Th and higher POC concentrations were observed in the upper 100 m layer inside the anticyclonic eddy compared with the outer area of the eddy (the reference site). We speculate that the peculiar feature of excess 234Th in the surface layer was caused by horizontal transport of POC into the eddy and consequent POC degradation and release of particulate 234Th to a dissolved form. However, in 2020, lower POC concentrations with 234Th deficiency were observed in both cyclonic and anticyclonic eddies relative to the reference site. In both years, POC export was lower in the cores of the anticyclonic and cyclonic eddies relative to the reference site. We propose that severe nutrient depletion in the upper 150 m layer hindered nutrient supply by vertical water movement in the eddies. Despite the low POC export at 100 m depth, POC export at 500 m depth was comparable to values observed at 500 m depth at Station Papa in the more productive northeastern Pacific region. Our results imply that POC export into the deep ocean interior in this region may not be as low as expected from the low primary productivity in the euphotic zone.

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Weak Response of Biological Productivity and Community Structure of Phytoplankton to Mesoscale Eddies in the Oligotrophic Philippine Sea

Cited by 16 publications

References 67 publications

Insignificant effects of eddies and typhoons on the biogeochemistry of the tropical northwest Pacific Ocean

Insignificant effects of eddies and typhoons on the biogeochemistry of the tropical northwest Pacific Ocean

Physiological characteristics of phytoplankton in response to different light environments in the Philippine Sea, Northwestern Pacific Ocean

Export of particulate organic carbon (POC) in the eddy region of the tropical northwest Pacific

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