How the source depth of coastal upwelling relates to stratification and wind

AbstractThe capacity of marine organisms to adapt and/or acclimate to climate change might differ among distinct populations, depending on their local environmental history and phenotypic plasticity. Kelp forests create some of the most productive habitats in the world, but globally, many populations have been negatively impacted by multiple anthropogenic stressors. Here, we compare the physiological and molecular responses to ocean acidification (OA) and warming (OW) of two populations of the giant kelp Macrocystis pyrifera from distinct upwelling conditions (weak vs strong). Using laboratory mesocosm experiments, we found that juvenile Macrocystis sporophyte responses to OW and OA did not differ among populations: elevated temperature reduced growth while OA had no effect on growth and photosynthesis. However, we observed higher growth rates and NO3− assimilation, and enhanced expression of metabolic-genes involved in the NO3− and CO2 assimilation in individuals from the strong upwelling site. Our results suggest that despite no inter-population differences in response to OA and OW, intrinsic differences among populations might be related to their natural variability in CO2, NO3− and seawater temperatures driven by coastal upwelling. Further work including additional populations and fluctuating climate change conditions rather than static values are needed to precisely determine how natural variability in environmental conditions might influence a species’ response to climate change.

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Volume and Nutrient Transports Disturbed by the Typhoon Chebi (2013) in the Upwelling Zone East of Hainan Island, China

Journal of Marine Science and Engineering ◽

10.3390/jmse9030324 ◽

2021 ◽

Vol 9 (3) ◽

pp. 324

Author(s):

Manli Zheng ◽

Lingling Xie ◽

Quanan Zheng ◽

Mingming Li ◽

Fajin Chen ◽

...

Keyword(s):

South China Sea ◽

Coastal Upwelling ◽

Unit Area ◽

Hainan Island ◽

Volume Transport ◽

Coastal Ocean ◽

Offshore Water ◽

Nutrient Distribution ◽

Before And After ◽

Ekman Flow

Using cruise observations before and after the typhoon Chebi in August 2013 and those without the typhoon in July 2012, this study investigates variations in current structure, nutrient distribution, and transports disturbed by a typhoon in a typical coastal upwelling zone east of Hainan Island in the northwestern South China Sea. The results show that along-shore northeastward flow dominates the coastal ocean with a volume transport of 0.64 × 106 m3/s in the case without the typhoon. The flow reversed southwestward, with its volume transport halved before the typhoon passage. After the typhoon passage, the flow returned back northeastward except the upper layer in waters deeper than 50 m and the total volume transport decreased to 0.10 × 106 m3/s. For the cross-shelf component, the flow kept shoreward, while transports crossing the 50 m isobath decreased from 0.25, 0.12 to 0.06 × 106 m3/s in the case without the typhoon as well as before and after typhoon passage, respectively. For the along-shore/cross-shelf nutrient transports, SiO32− has the largest value of 866.13/632.74 μmol/s per unit area, NO3− half of that, and PO43− and NO2− one order smaller in the offshore water without the typhoon. The values dramatically decreased to about one-third for SiO32−, NO3−, and PO43− after the typhoon, but changed little for NO2−. The disturbed wind field and associated Ekman flow and upwelling process may explain the variations in the current and nutrient transports after the typhoon.

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Seasonal Variability of SST Fronts in the Inner Sea of Chiloé and Its Adjacent Coastal Ocean, Northern Patagonia

Remote Sensing ◽

10.3390/rs13020181 ◽

2021 ◽

Vol 13 (2) ◽

pp. 181

Author(s):

Gonzalo S. Saldías ◽

Wilber Hernández ◽

Carlos Lara ◽

Richard Muñoz ◽

Cristian Rojas ◽

...

Keyword(s):

Coastal Upwelling ◽

Environmental Variability ◽

Function Analysis ◽

Coastal Ocean ◽

Dominant Mode ◽

Early Summer ◽

High Biological Activity ◽

Northern Patagonia ◽

Sst Gradient ◽

Sst Fronts

Surface oceanic fronts are regions characterized by high biological activity. Here, Sea Surface Temperature (SST) fronts are analyzed for the period 2003–2019 using the Multi-scale Ultra-high Resolution (MUR) SST product in northern Patagonia, a coastal region with high environmental variability through river discharges and coastal upwelling events. SST gradient magnitudes were maximum off Chiloé Island in summer and fall, coherent with the highest frontal probability in the coastal oceanic area, which would correspond to the formation of a coastal upwelling front in the meridional direction. Increased gradient magnitudes in the Inner Sea of Chiloé (ISC) were found primarily in spring and summer. The frontal probability analysis revealed the highest occurrences were confined to the northern area (north of Desertores Islands) and around the southern border of Boca del Guafo. An Empirical Orthogonal Function analysis was performed to clarify the dominant modes of variability in SST gradient magnitudes. The meridional coastal fronts explained the dominant mode (78% of the variance) off Chiloé Island, which dominates in summer, whereas the SST fronts inside the ISC (second mode; 15.8%) were found to dominate in spring and early summer (October–January). Future efforts are suggested focusing on high frontal probability areas to study the vertical structure and variability of the coastal fronts in the ISC and its adjacent coastal ocean.

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Environmental Effects on the Spatiotemporal Variability of Fish Larvae in the Western Guangdong Waters, China

Journal of Marine Science and Engineering ◽

10.3390/jmse9030316 ◽

2021 ◽

Vol 9 (3) ◽

pp. 316

Author(s):

Yuting Feng ◽

Lijun Yao ◽

Hui Zhao ◽

Jing Yu ◽

Zhaojin Lin

Keyword(s):

Environmental Effects ◽

Coastal Upwelling ◽

Fish Larvae ◽

Additive Models ◽

Sea Surface ◽

Sea Surface Salinity ◽

Spatiotemporal Variability ◽

Aquatic Life ◽

Positive Effects ◽

Fishery Resources

Spawning grounds occupy an important position in the survival and reproduction of aquatic life, which plays an important role in the replenishment of fishery resources, especially in the China coasts where fishery resources are depleting. This study investigated environmental effects on the spatiotemporal variability of fish larvae in the western Guangdong waters (WGWs), on the basis of generalized additive models (GAMs) and center of gravity (CoG). Satellite data including sea surface salinity (SSS), sea surface temperature (SST), and in situ observations for fish larvae from April to June in 2014–2015 were used. Results showed that 40.3% of the total variation in fish larvae density was explained. SST, SSS, and depth showed positive effects in 23–24 °C and 27–30 °C, 24–32 PSU, and 0–60 m, and showed negative effects in 24–27 °C, 32–34.2 PSU, 60–80 m. Based on the stepwise GAMs, the most important factor was month, with a contribution of 10.6%, followed by longitude, offshore distance, depth, and latitude, with contributions of 7.0%, 7.0%, 6.3%, 4.2%, 3.9%, and 1.3%, respectively. Fish larvae CoG shifted northward by 0.6° N and eastwards by 0.13° E from April to June. The distribution of fish larvae in the WGWs was affected by complex submarine topography in the Qiongzhou Strait, coastal upwelling in the WGWs, and runoff from the Pearl River.

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