Contrasting ENSO Types With Satellite‐Derived Ocean Phytoplankton Biomass in the Tropical Pacific

Sharma, Priya; Singh, Awnesh; Marinov, I.; Kostadinov, T. S.

doi:10.1029/2018gl080689

Cited by 5 publications

(6 citation statements)

References 65 publications

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“…Apart from the coastal region, strong Chl-a variability can be observed in the equatorial western Pacific, i.e., the western part of the Niño 4 region (160°E-175°W, 5°S-5°N, red box in figure 1(a); defined as the Niño 4 W region thereafter), and a narrow band spanning the equatorial central-eastern Pacific. Similar patterns have also been found in previous studies either by using standard deviation maps [38] or empirical orthogonal functions (EOFs) [39]. Although the center of strong variability can be detected both in the eastern and western part of the equatorial Pacific, their climatological background is rather different (figure 1(a); contour lines).…”

Section: Phytoplankton Blooms During 'Double-dip' La Niña Eventssupporting

confidence: 86%

Nonlinear response of Equatorial Western Pacific phytoplankton blooms to ‘double-dip’ La Niña events

Chen

Zhang

et al. 2023

Environ. Res. Commun.

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Phytoplankton in the equatorial western Pacific tends to bloom during consecutive (“double-dip”) La Niña events with nonlinear characteristics: extremely high chlorophyll-a (Chl-a) concentrations typically occur during the second-year La Niña events even when the associated SST anomalies are significantly weakened. Photosynthetically available radiation is found to have the strongest correlation with the equatorial western Pacific Chl-a fluctuations. However, barrier layer variation is critical in driving the strong bloom events seen in the second-year La Niña, which can be further explained by the nonlinear heat advection within the isothermal layer. To improve the current climate models’ performance in simulating the western Pacific phytoplankton bloom events, it is recommended that the influence of barrier layer should be better considered.

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Section: Phytoplankton Blooms During 'Double-dip' La Niña Eventssupporting

confidence: 86%

Nonlinear response of Equatorial Western Pacific phytoplankton blooms to ‘double-dip’ La Niña events

Chen

Zhang

et al. 2023

Environ. Res. Commun.

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“…By contrast, during La Niña events, high Chl-a and high phytoplankton biomass are observed due to the steepening of the basin gradient of the thermocline and nutricline across the tropical Pacific. This promotes the upwelling of water with high nitrate and iron concentrations into the euphotic layer in the eastern Pacific and, therefore, higher phytoplankton growth [22,24,25]. The ENSO effects are also reported for coral reefs in the tropics, which exhibit patterns of recovery and resilience in the ETP, except under extreme temperature events [26].…”

Section: Introductionmentioning

confidence: 82%

“…However, we could not test these assumptions, and they should be explored in future work, preferably through determining biomass-specific carbon fixation rates under different temperatures (as the independent variable) and nutrient supply conditions. Moreover, considering that (i) variations in the tropical phytoplankton community structure are strongly linked to ENSO events, and (ii) the use of Chl-a data alone causes bias in the estimation of phytoplankton biomass, which can be misleading when the relationships between physical drivers and phytoplankton growth are evaluated [24,69].…”

Section: Marchmentioning

confidence: 99%

“…In addition, the long and persistent positive sea surface temperature anomalies enhance the vertical stratification and deepen the thermocline in the tropical Pacific [22,23]. This, along with a deepening of the nutricline, decreases the availability of nutrients and dilutes the phytoplankton cells in the upper layer, restricting sunlight for photosynthesis and phytoplankton growth, and this is reflected in their biomass decrease [19,20,24]. By contrast, during La Niña events, high Chl-a and high phytoplankton biomass are observed due to the steepening of the basin gradient of the thermocline and nutricline across the tropical Pacific.…”

Section: Introductionmentioning

confidence: 99%

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Spatio-Temporal Variability of Chlorophyll-A and Environmental Variables in the Panama Bight

et al. 2020

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The analysis of synoptic satellite data of total chlorophyll-a (Chl-a) and the environmental drivers that influence nutrient and light availability for phytoplankton growth allows us to understand the spatio-temporal variability of phytoplankton biomass. In the Panama Bight Tropical region (PB; 1–9°N, 79–84°W), the spatial distribution of Chl-a is mostly related to the seasonal wind patterns and the intensity of localized upwelling centers. However, the association between the Chl-a and different physical variables and nutrient availability is still not fully assessed. In this study, we evaluate the relationship between the Chl-a and multiple physical (wind, Ekman pumping, geostrophic circulation, mixed layer depth, sea level anomalies, river discharges, sea surface temperature, and photosynthetically available radiation) and chemical (nutrients) drivers in order to explain the spatio-temporal Chl-a variability in the PB. We used satellite data of Chl-a and physical variables, and a re-analysis of a biogeochemical product for nutrients (2002–2016). Our results show that at the regional scale, the Chl-a varies seasonally in response to the wind forcing and sea surface temperature. However, in the coastal areas (mainly Gulf of Panama and off central-southern Colombia), the maximum non-seasonal Chl-a values are found in association with the availability of nutrients by river discharges, localized upwelling centers and the geostrophic circulation field. From this study, we infer that the interplay among these physical-chemical drivers is crucial for supporting the phytoplankton growth and the high biodiversity of the PB region.

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“…El Niño decreases BET:SKJ catch ratios east of ∼170°E and increases ratios west of ∼170°E, while La Niña acts in the opposite direction (Fig 4c-d; Fig 5c). The effects of El Niño and La Niña on BET:SKJ catch ratios thus oppose one another in the WTP, as is also the case for temperature, dissolved oxygen content, primary productivity, and other environmental variables (e.g., [25,53,54]).…”

Section: Resultsmentioning

confidence: 93%

ENSO drives lateral separation of FAD-associated skipjack and bigeye tuna in the Western Tropical Pacific

Leung

Mislan

Thompson

2020

Preprint

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14Incidental capture of juvenile bigeye tuna in fish aggregating device (FAD)-associated 15 purse seine fisheries targeting skipjack tuna have contributed significantly to the degradation of 16 bigeye stocks in the Western Tropical Pacific (WTP) Ocean. One way to reduce this incidental 17 catch is to simply limit purse seine fishing effort; however, skipjack tuna stocks are healthy and 18 economically important to many small island nations in the region. Here we assess whether there 19 is sufficient lateral separation of skipjack and bigeye within FAD-associated purse seine fisheries 20 in the WTP to allow limiting bigeye catch while maintaining a robust skipjack fishery. Based on 21 monthly 5°-longitude-by-5°-latitude catch and effort data, FAD-associated bigeye and skipjack 22 catch per unit effort (CPUE) covary tightly throughout the WTP, such that lateral separation 23 between the two species is generally small. There are, however, significant variations in the 24 amount of separation over both space and time. Waters within the Party to the Nauru Agreement 25 exclusive economic zones (EEZs) belonging to Palau, Solomon Islands, and Tuvalu regularly 26 exhibit some of the smallest bigeye-to-skipjack catch ratios, especially during El Niño. In 27 contrast, waters within Kiribati's Phoenix Islands EEZ regularly exhibit some of the largest 28 bigeye-to-skipjack catch ratios, which are particularly high during La Niña. In general, El Niño 29 lowers bigeye-to-skipjack catch ratios east of 170°E, while La Niña lowers bigeye-to-skipjack 30 catch ratios west of 170°E. These ENSO-driven variations in separability are larger and more 31 widespread than those driven by seasonality, due to larger associated variations in environmental 32 conditions. Sea surface height anomalies may be particularly useful for demarcating the different 33 environments preferred by skipjack and bigeye throughout the WTP. Sea surface temperatures, 34 temperatures at 100 m, and thermocline depths may also help distinguish between the two 35 species' preferred habitats in many areas. These analyses can help better inform the complex 3 36 decisions made by both fishers during operations and fisheries managers during creation of 37 effective, dynamic policies to preserve bigeye stocks in the WTP. They also show that climate 38 variability can have substantial effects on the spatial distributions of top pelagic predators and 39 their interactions with one another. 40 1 Introduction 41 The Western and Central Pacific Ocean (WCPO) accounts for more than 60% of total 42 global tuna catch [1]. Tuna and other highly migratory species in this region are managed by the 43 Western and Central Pacific Fisheries Commission (WCPFC), which is one of five tuna Regional 44 Fishing Management Organizations in operation around the world. The most commonly fished 45 tuna species in the WCPO are skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), 46 bigeye (Thunnus obesus), and albacore tuna (Thunnus alalunga) [2]. Though these sought-after 47 tuna species...

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Contrasting ENSO Types With Satellite‐Derived Ocean Phytoplankton Biomass in the Tropical Pacific

Cited by 5 publications

References 65 publications

Nonlinear response of Equatorial Western Pacific phytoplankton blooms to ‘double-dip’ La Niña events

Nonlinear response of Equatorial Western Pacific phytoplankton blooms to ‘double-dip’ La Niña events

Spatio-Temporal Variability of Chlorophyll-A and Environmental Variables in the Panama Bight

ENSO drives lateral separation of FAD-associated skipjack and bigeye tuna in the Western Tropical Pacific

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