Phytoplankton growth and microzooplankton grazing in a subtropical coastal upwelling system in the Taiwan Strait

2011 ◽  
Vol 31 (6) ◽  
pp. S48-S56 ◽  
Author(s):  
Bangqin Huang ◽  
Weiguo Xiang ◽  
Xiangbo Zeng ◽  
Kuo-Ping Chiang ◽  
Haojie Tian ◽  
...  
Keyword(s):  
Coastal Upwelling ◽  
Taiwan Strait ◽  
Phytoplankton Growth ◽  
Upwelling System ◽  
The Taiwan Strait ◽  
Microzooplankton Grazing

scholarly journals Responses of Summer Upwelling to Recent Climate Changes in the Taiwan Strait

2021 ◽  
Vol 13 (7) ◽  
pp. 1386
Author(s):  
Caiyun Zhang
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Coastal Upwelling ◽  
Taiwan Strait ◽  
Sea Surface ◽  
Enso Events ◽  
Upwelling System ◽  
Recent Climate ◽  
Upwelling Intensity ◽  
The Taiwan Strait

The response of a summer upwelling system to recent climate change in the Taiwan Strait has been investigated using a time series of sea surface temperature and wind data over the period 1982–2019. Our results revealed that summer upwelling intensities of the Taiwan Strait decreased with a nonlinear fluctuation over the past four decades. The average upwelling intensity after 2000 was 35% lower than that before 2000. The long-term changes in upwelling intensities show strong correlations with offshore Ekman transport, which experienced a decreasing trend after 2000. Unlike the delay effect of canonical ENSO events on changes in summer upwelling, ENSO Modoki events had a significant negative influence on upwelling intensity. Strong El Niño Modoki events were not favorable for the development of upwelling. This study also suggested that decreased upwelling could not slow down the warming rate of the sea surface temperature and would probably cause the decline of chlorophyll a in the coastal upwelling system of the Taiwan Strait. These results will contribute to a better understanding of the dynamic process of summer upwelling in the Taiwan Strait, and provide a sound scientific basis for evaluating future trends in coastal upwelling and their potential ecological effects.

scholarly journals Nitrogen fixation in two coastal upwelling regions of the Taiwan Strait

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Zuozhu Wen ◽  
Wenfang Lin ◽  
Rong Shen ◽  
Haizheng Hong ◽  
Shuh-Ji Kao ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Coastal Upwelling ◽  
Taiwan Strait ◽  
The Taiwan Strait

scholarly journals MODIS observed phytoplankton dynamics in the Taiwan Strait: an absorption-based analysis

2011 ◽  
Vol 8 (4) ◽  
pp. 841-850 ◽  
Author(s):  
S. Shang ◽  
Q. Dong ◽  
Z. Lee ◽  
Y. Li ◽  
Y. Xie ◽  
...  
Keyword(s):  
Coastal Upwelling ◽  
Sea Water ◽  
River Estuary ◽  
Taiwan Strait ◽  
Percentage Error ◽  
Nutrient Loads ◽  
Phytoplankton Dynamics ◽  
Average Percentage ◽  
The Taiwan Strait

Abstract. This study used MODIS observed phytoplankton absorption coefficient at 443 nm (Aph) as a preferable index to characterize phytoplankton variability in optically complex waters. Aph derived from remote sensing reflectance (Rrs, both in situ and MODIS measured) with the Quasi-Analytical Algorithm (QAA) were evaluated by comparing them with match-up in situ measurements, collected in both oceanic and nearshore waters in the Taiwan Strait (TWS). For the data with matching spatial and temporal window, it was found that the average percentage error (ε) between MODIS derived Aph and field measured Aph was 33.8% (N=30, Aph ranges from 0.012 to 0.537 m−1), with a root mean square error in log space (RMSE_log) of 0.226. By comparison, ε was 28.0% (N=88, RMSE_log = 0.150) between Aph derived from ship-borne Rrs and Aph measured from water samples. However, values of ε as large as 135.6% (N=30, RMSE_log = 0.383) were found between MODIS derived chlorophyll-a (Chl, OC3M algorithm) and field measured Chl. Based on these evaluation results, we applied QAA to MODIS Rrs data in the period of 2003–2009 to derive climatological monthly mean Aph for the TWS. Three distinct features of phytoplankton dynamics were identified. First, Aph is low and the least variable in the Penghu Channel, where the South China Sea water enters the TWS. This region maintains slightly higher values in winter (~17% higher than that in the other seasons) due to surface nutrient entrainment under winter wind-driven vertical mixing. Second, Aph is high and varies the most in the mainland nearshore water, with values peaking in summer (June–August) when river plumes and coastal upwelling enhance surface nutrient loads. Interannual variation of bloom intensity in Hanjiang River estuary in June is highly correlated with alongshore wind stress anomalies, as observed by QuikSCAT. The year of minimum and maximum bloom intensity is in the midst of an El Niño and a La Niña event, respectively. Third, a high Aph patch appears between April and September in the middle of the southern TWS, corresponding to high thermal frontal probabilities, as observed by MODIS. Our results support the use of satellite derived Aph for time series analyses of phytoplankton dynamics in coastal ocean regions, whereas satellite Chl products derived empirically using spectral ratio of Rrs suffer from artifacts associated with non-biotic optically active materials.

Interannual variability of summer coastal upwelling in the Taiwan Strait

2009 ◽  
Vol 29 (2) ◽  
pp. 479-484 ◽  
Author(s):  
Huasheng Hong ◽  
Caiyun Zhang ◽  
Shaoling Shang ◽  
Bangqin Huang ◽  
Yonghong Li ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Coastal Upwelling ◽  
Taiwan Strait ◽  
The Taiwan Strait

scholarly journals Low nutrient and high chlorophyll a coastal upwelling system – A case study in the southern Taiwan Strait

2015 ◽  
Vol 166 ◽  
pp. 170-177 ◽  
Author(s):  
Jun Hu ◽  
Wenlu Lan ◽  
Bangqin Huang ◽  
Kuo-Ping Chiang ◽  
Huasheng Hong
Keyword(s):  
Chlorophyll A ◽  
Coastal Upwelling ◽  
Taiwan Strait ◽  
Upwelling System ◽  
System A ◽  
Southern Taiwan

scholarly journals Effects of upwelling duration and phytoplankton growth regime on dissolved oxygen levels in an idealized Iberian Peninsula upwelling system

2019 ◽  
Author(s):  
João H. Bettencourt ◽  
Vincent Rossi ◽  
Lionel Renault ◽  
Peter Haynes ◽  
Yves Morel ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Iberian Peninsula ◽  
Coastal Upwelling ◽  
Net Primary Production ◽  
Coastal Region ◽  
Phytoplankton Growth ◽  
Biogeochemical Model ◽  
Nutrient Inputs ◽  
Upwelling System ◽  
Growth Regime

Abstract. We apply a coupled modelling system composed of a state-of-the-art hydrodynamical model and a low complexity biogeochemical model to an idealized Iberian Peninsula upwelling system to identify the main drivers of dissolved oxygen variability and to study its response to changes in the duration of the upwelling season and in phytoplankton growth regime. We find that the export of oxygenated waters by upwelling front turbulence is a major sink for nearshore dissolved oxygen. In our simulations of summer upwelling, when phytoplankton population is generally dominated by diatoms whose growth is largely enhanced by nutrient input, net primary production and air-sea exchange compensate dissolved oxygen depletion by offshore export over the shelf. A shorter upwelling duration causes relaxation of upwelling winds and a decrease in offshore export, resulting in a slight increase of net dissolved oxygen enrichment in the coastal region as compared to longer upwelling durations. When phytoplankton is dominated by groups less sensitive to nutrient inputs, growth rates decrease and the coastal region becomes net heterotrophic. Together with the physical sink, this lowers the net oxygenation rate of coastal waters, that remains positive only because of air-sea exchanges. These findings help disentangling the physical and biogeochemical controls of dissolved oxygen in upwelling systems and, together with projections of increased duration of upwelling seasons and phytoplankton community changes, suggest that the Iberian coastal upwelling region may become more vulnerable to hypoxia and deoxygenation.

scholarly journals What drives the spatial variability of primary productivity and matter fluxes in the north-west African upwelling system? A modelling approach

2016 ◽  
Vol 13 (23) ◽  
pp. 6419-6440 ◽  
Author(s):  
Pierre-Amaël Auger ◽  
Thomas Gorgues ◽  
Eric Machu ◽  
Olivier Aumont ◽  
Patrice Brehmer
Keyword(s):  
Large Scale ◽  
Coastal Upwelling ◽  
Phytoplankton Growth ◽  
Coastal Circulation ◽  
New Production ◽  
North West ◽  
Upwelling System ◽  
The North ◽  
Coastal Phytoplankton ◽  
Lateral Advection

Abstract. A comparative box analysis based on a multi-decadal physical–biogeochemical hindcast simulation (1980–2009) was conducted to characterize the drivers of the spatial distribution of phytoplankton biomass and production in the north-west (NW) African upwelling system. Alongshore geostrophic flow related to large-scale circulation patterns associated with the influence of coastal topography is suggested to modulate the coastal divergence, and then the response of nutrient upwelling to wind forcing. In our simulation, this translates into a coastal upwelling of nitrate being significant in all regions but the Cape Blanc (CB) area. However, upwelling is found to be the dominant supplier of nitrate only in the northern Saharan Bank (NSB) and the Senegalo-Mauritanian (SM) regions. Elsewhere, nitrate supply is dominated by meridional advection, especially off Cape Blanc. Phytoplankton displays a similar behaviour with a supply by lateral advection which equals the net coastal phytoplankton growth in all coastal regions except the Senegalo-Mauritanian area. Noticeably, in the Cape Blanc area, the net coastal phytoplankton growth is mostly sustained by high levels of regenerated production exceeding new production by more than twofold, which is in agreement with the locally weak input of nitrate by coastal upwelling. Further offshore, the distribution of nutrients and phytoplankton is explained by the coastal circulation. Indeed, in the northern part of our domain (i.e. Saharan Bank), the coastal circulation is mainly alongshore, resulting in low offshore lateral advection of nutrients and phytoplankton. Conversely, lateral advection transports coastal nutrients and phytoplankton towards offshore areas in the latitudinal band off the Senegalo-Mauritanian region. Moreover, this latter offshore region benefits from transient southern intrusions of nutrient-rich waters from the Guinean upwelling.

scholarly journals MODIS observed phytoplankton dynamics in the Taiwan Strait: an absorption-based analysis

2010 ◽  
Vol 7 (5) ◽  
pp. 7795-7819 ◽  
Author(s):  
S. Shang ◽  
Q. Dong ◽  
Z. Lee ◽  
Y. Li ◽  
Y. Xie ◽  
...  
Keyword(s):  
Coastal Upwelling ◽  
Sea Water ◽  
River Estuary ◽  
Taiwan Strait ◽  
Percentage Error ◽  
Phytoplankton Dynamics ◽  
Chl A ◽  
Average Percentage ◽  
The Taiwan Strait

Abstract. This study uses MODIS observed phytoplankton absorption coefficient (aph) as a preferable index of pigmentation to characterize phytoplankton variability in optically complex waters. We chose a quasi-analytical bio-optical inversion algorithm (QAA) to derive aph from remote sensing reflectance (Rrs, both in situ and MODIS measured) and then evaluated the Rrs derived aph by comparing them with match-up in situ measured aph collected in both oceanic and very nearshore waters in the Taiwan Strait (TWS). For the data with matching spatial and temporal window, it is found that the average percentage error (ε) between MODIS Rrs derived aph at 443 nm (aph(443), abbreviated as Aph) and field measured Aph is 33.8% (N = 30, Aph ranges from 0.012–0.537 m−1), with a root mean square error in log scale (RMSE) of 0.226. By comparison, ε is 28.0% (N = 88, RMSE = 0.150) between ship-borne Rrs derived Aph and field measured Aph. Values of ε as large as 135.6% (N = 30, RMSE = 0.383) are found between MODIS Rrs derived chlorophyll-a (chl-a, OC3M algorithm) and field measured chl-a. Based on these evaluation results, we applied QAA to MODIS Rrs data between 2003–2009 to derive climatological monthly mean Aph for the TWS. Three distinct features of phytoplankton dynamics are identified. First, Aph is low and the least variable in the Penghu Channel, where the South China Sea water enters the TWS. This region maintains slightly higher values in winter (~17% higher than that in the other seasons) due to surface nutrient entrainment under winter wind-driven vertical mixing. Second, Aph is high and the most variable in the mainland nearshore water, with values peaking in summer (June–August) when river plumes and coastal upwelling enhance surface nutrient loads. Interannual variation of bloom intensity in Hanjiang River estuary in June is highly correlated with alongshore wind stress anomalies, as observed by QuikSCAT. The year of minimum and maximum bloom intensity is in the midst of an El Nino and a La Nina event, respectively. Third, a high Aph patch appears between April and September in the middle of the Southern TWS, corresponding to high thermal frontal probabilities, as observed by MODIS. Our results support the use of satellite observed Aph for time series analyses of phytoplankton dynamics in coastal ocean regions, where satellite chl-a retrievals can suffer from artifacts associated with non-biotic optically active materials.

scholarly journals Effects of upwelling duration and phytoplankton growth regime on dissolved-oxygen levels in an idealized Iberian Peninsula upwelling system

2020 ◽  
Vol 27 (2) ◽  
pp. 277-294
Author(s):  
João H. Bettencourt ◽  
Vincent Rossi ◽  
Lionel Renault ◽  
Peter Haynes ◽  
Yves Morel ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Iberian Peninsula ◽  
Coastal Upwelling ◽  
Net Primary Production ◽  
Coastal Region ◽  
Phytoplankton Growth ◽  
Biogeochemical Model ◽  
Nutrient Inputs ◽  
Upwelling System ◽  
Growth Regime

Abstract. We apply a coupled modelling system composed of a state-of-the-art hydrodynamical model and a low-complexity biogeochemical model to an idealized Iberian Peninsula upwelling system to identify the main drivers of dissolved-oxygen variability and to study its response to changes in the duration of the upwelling season and in the phytoplankton growth regime. We find that the export of oxygenated waters by upwelling front turbulence is a major sink for nearshore dissolved oxygen. In our simulations of summer upwelling, when the phytoplankton population is generally dominated by diatoms whose growth is boosted by nutrient input, net primary production and air–sea exchange compensate dissolved-oxygen depletion by offshore export over the shelf. A shorter upwelling duration causes a relaxation of upwelling winds and a decrease in offshore export, resulting in a slight increase of net dissolved-oxygen enrichment in the coastal region as compared to longer upwelling durations. When phytoplankton is dominated by groups less sensitive to nutrient inputs, growth rates decrease, and the coastal region becomes net heterotrophic. Together with the physical sink, this lowers the net oxygenation rate of coastal waters, which remains positive only because of air–sea exchange. These findings help in disentangling the physical and biogeochemical controls of dissolved oxygen in upwelling systems and, together with projections of increased duration of upwelling seasons and phytoplankton community changes, suggest that the Iberian coastal upwelling region may become more vulnerable to hypoxia and deoxygenation.

scholarly journals What drives the spatial variability of primary productivity and matter fluxes in the North-West African upwelling system? A modelling approach and box analysis

2016 ◽  
Author(s):  
Pierre-Amaël Auger ◽  
Thomas Gorgues ◽  
Eric Machu ◽  
Olivier Aumont ◽  
Patrice Brehmer
Keyword(s):  
Large Scale ◽  
Coastal Upwelling ◽  
Phytoplankton Growth ◽  
Coastal Circulation ◽  
New Production ◽  
North West ◽  
Upwelling System ◽  
The North ◽  
Coastal Phytoplankton ◽  
Lateral Advection

Abstract. A comparative box analysis based on a multi-decadal physical-biogeochemical hindcast simulation (1980–2009) was conducted to characterize the drivers of the spatial distribution of phytoplankton biomass and production in the North-West (NW) African upwelling system. Alongshore geostrophic flow related to large scale circulation patterns associated with the influence of coastal topography are suggested to modulate the coastal divergence, and then the response of nutrient upwelling to wind forcings. In our simulation, this translates into a coastal upwelling of nitrate being significant in all regions but the Cape Blanc (CB) area. However, upwelling is found to be the dominant supplier of nitrate only in the northern Saharan Bank (NSB) and the Senegalo-Mauritanian (SM) regions. Elsewhere, nitrate supply is dominated by meridional advection, especially off Cape Blanc. Phytoplankton displays a similar behaviour with a supply by lateral advection which equals the net coastal phytoplankton growth in all coastal regions except the Senegalo-Mauritanian area. Noticeably, in the Cape Blanc area, the net coastal phytoplankton growth is mostly sustained by high levels of regenerated production exceeding new production by more than two fold which is in agreement with the locally weak input of nitrate by coastal upwelling. Further offshore, the distribution of nutrients and phytoplankton is explained by the coastal circulation. Indeed, in the northern part of our domain (i.e. Saharan Bank), the coastal circulation is mainly alongshore resulting in low offshore lateral advection of nutrients and phytoplankton. On the contrary, lateral advection transport coastal nutrients and phytoplankton towards offshore areas in the latitudinal band off the Senegalo-Mauritanian region. Moreover, this latter offshore region benefits from transient southern intrusions of nutrient-rich waters from the Guinean upwelling.

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