scholarly journals Seasonal and interannual variability of phytoplankton abundance and community composition on the Central Coast of California

2020 ◽  
Vol 637 ◽  
pp. 29-43 ◽  
Author(s):  
A Barth ◽  
RK Walter ◽  
I Robbins ◽  
A Pasulka
Keyword(s):  
Interannual Variability ◽  
Phytoplankton Community ◽  
Coastal Upwelling ◽  
Current System ◽  
Ecosystem Dynamics ◽  
Nutrient Concentrations ◽  
Ecosystem Structure ◽  
Phytoplankton Abundance ◽  
California Current System ◽  
Seasonal And Interannual Variability

Variations in the abundance and composition of phytoplankton greatly impact ecosystem structure and function. Within the California Current System (CCS), phytoplankton community structure is tightly coupled to seasonal variability in wind-driven coastal upwelling, a process that drives changes in coastal water temperatures and nutrient concentrations. Based on approximately a decade (2008-2018) of weekly phytoplankton measurements, this study provides the first characterization of the seasonal and interannual variability of phytoplankton abundance and composition in San Luis Obispo (SLO) Bay, an understudied region within the CCS. Overall, the seasonality of phytoplankton in SLO Bay mirrored that of the larger CCS; diatoms dominated the community during the spring upwelling season, whereas dinoflagellates dominated the community during the fall relaxation period. While we observed considerable interannual variability among phytoplankton taxa, of particular note was the absence of a fall dinoflagellate-dominated period from 2010 through 2013, followed by the return of the fall dinoflagellate-dominated period in 2014. This compositional shift coincided with a major phase shift of both the Pacific Decadal Oscillation (PDO) and North Pacific Gyre Oscillation (NPGO). In addition to exerting a strong influence on the seasonality of phytoplankton community succession and transition between diatom- and dinoflagellate-dominated periods, the state of both the PDO and NPGO also influenced the extent to which environmental conditions (temperature and upwelling winds) could predict community type. These results highlight the importance of long-term datasets and the consideration of large-scale climate patterns when assessing local ecosystem dynamics.

scholarly journals What controls biological production in coastal upwelling systems? Insights from a comparative modeling study

2011 ◽  
Vol 8 (10) ◽  
pp. 2961-2976 ◽  
Author(s):  
Z. Lachkar ◽  
N. Gruber
Keyword(s):  
Coastal Upwelling ◽  
Net Primary Production ◽  
Current System ◽  
Nutrient Recycling ◽  
Coupled Model ◽  
Comparative Modeling ◽  
Nutrient Concentrations ◽  
Residence Times ◽  
California Current System ◽  
Modeling Study

Abstract. The magnitude of net primary production (NPP) in Eastern Boundary Upwelling Systems (EBUS) is traditionally viewed as directly reflecting the wind-driven upwelling intensity. Yet, different EBUS show different sensitivities of NPP to upwelling-favorable winds (Carr and Kearns, 2003). Here, using a comparative modeling study of the California Current System (California CS) and Canary Current System (Canary CS), we show how physical and environmental factors, such as light, temperature and cross-shore circulation modulate the response of NPP to upwelling strength. To this end, we made a series of eddy-resolving simulations of the two upwelling systems using the Regional Oceanic Modeling System (ROMS), coupled to a nitrogen-based Nutrient-Phytoplankton-Zooplankton-Detritus (NPZD) ecosystem model. Using identical ecological/biogeochemical parameters, our coupled model simulates a level of NPP in the California CS that is 50 % smaller than that in the Canary CS, in agreement with observationally based estimates. We find this much lower NPP in the California CS despite phytoplankton in this system having nearly 20 % higher nutrient concentrations available to fuel their growth. This conundrum can be explained by: (1) phytoplankton having a faster nutrient-replete growth in the Canary CS relative to the California CS; a consequence of more favorable light and temperature conditions in the Canary CS, and (2) the longer nearshore water residence times in the Canary CS, which permit a larger buildup of biomass in the upwelling zone, thereby enhancing NPP. The longer residence times in the Canary CS appear to be a result of the wider continental shelves and the lower mesoscale activity characterizing this upwelling system. This results in a weaker offshore export of nutrients and organic matter, thereby increasing local nutrient recycling and reducing the spatial decoupling between new and export production in the Canary CS. Our results suggest that climate change-induced perturbations such as upwelling favorable wind intensification might lead to contrasting biological responses in the California CS and the Canary CS, with major implications for the biogeochemical cycles and fisheries in these two ecosystems.

Impact of assimilating physical oceanographic data on modeled ecosystem dynamics in the California Current System

2015 ◽  
Vol 138 ◽  
pp. 546-558 ◽  
Author(s):  
Kaustubha Raghukumar ◽  
Christopher A. Edwards ◽  
Nicole L. Goebel ◽  
Gregoire Broquet ◽  
Milena Veneziani ◽  
...  
Keyword(s):  
Current System ◽  
California Current ◽  
Ecosystem Dynamics ◽  
California Current System ◽  
Oceanographic Data

Chlorophyll-a distribution and mesoscale physical processes in upwelling and adjacent oceanic zones off northern Chile (summer–autumn 1994)

2001 ◽  
Vol 81 (2) ◽  
pp. 193-206 ◽  
Author(s):  
Carmen E. Morales ◽  
José L. Blanco ◽  
Mauricio Braun ◽  
Nelson Silva
Keyword(s):  
Coastal Upwelling ◽  
Current System ◽  
Austral Summer ◽  
Nutrient Concentrations ◽  
Northern Chile ◽  
Humboldt Current ◽  
Oxygen Conditions ◽  
Salinity Water ◽  
Humboldt Current System ◽  
Seasonal Signal

Chlorophyll-a (chl-a) distribution and associated physical (temperature, salinity) and chemical (dissolved oxygen) conditions off northern Chile (Humboldt Current System), during the austral summer (February–March) and autumn (May) of 1994, were studied in the region bounded by ∼18–24°S and 70–72°W (out to ∼200 km from the coast; 0–100 m depth); within this region, nutrients were measured in an area of persistent coastal upwelling (∼19–22°S, out to 80 km from the coast). Temperature and salinity distributions, as well as nutrient concentrations, indicated the occurrence of active upwelling during both cruises. Also, and together with maps of geopotential anomaly (0/200 dbar) and depth of the thermocline (15°C isotherm), their distribution suggested the presence of a mainly equatorward flow, anticyclonic eddy-like structures, and intrusions of warm (>19°C), high salinity (>35·0 psu), subtropical water towards the coast. A tongue of cooler and lower salinity water, and of lower flow fields, extended from the coast towards the offshore zone during both sampling periods, in association with higher chl-a concentrations (>1 mg m−3, >20 mg m−2 between 0 and 25 m depth) and predominance of net-phytoplankton (>20 μm). The comparison of these results with those for the winter and spring of 1993 in the same area suggest a relatively weak seasonal signal in chl-a concentration during the 1993–1994 period, with higher water column concentrations during the summer and spring periods in the selected upwelling area, though surface chl-a concentrations for the whole of the area did not vary significantly.

scholarly journals Marine Bird Attraction to Thermal Fronts in the California Current System

The Condor ◽  
2000 ◽  
Vol 102 (2) ◽  
pp. 423-427 ◽  
Author(s):  
Christopher J. Hoefer
Keyword(s):  
Coastal Upwelling ◽  
Current System ◽  
California Current ◽  
Similar Data ◽  
Marine Bird ◽  
California Current System ◽  
Oceanodroma Leucorhoa ◽  
Bird Density ◽  
Leach’S Storm Petrel ◽  
Storm Petrel

AbstractI relate marine bird density to the 55 strongest thermal fronts encountered during a survey of much of the eastern portion of the California Current and the adjacent coastal upwelling region. Elevated densities were recorded for all marine bird taxa except the Leach's Storm-Petrel (Oceanodroma leucorhoa). The variance explained by the regression models ranged from 3% for the Leach's Storm-Petrel to 85% for all marine birds. The response observed is notably stronger than previous analyses with similar data.

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