Biogeography and phenology of satellite-measured phytoplankton seasonality in the California current

Foukal, Nicholas P.; Thomas, Andrew C.

doi:10.1016/j.dsr.2014.06.008

Cited by 24 publications

(37 citation statements)

References 76 publications

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“…Our regimes differ from those described by Foukal and Thomas [], who use multivariate clustering based on the shape of previously derived seasonal cycles to identify different marine spatial groupings. In that study, the authors define the coastal area from northern Vancouver Island to Point Conception as one group that has the highest surface chlorophyll concentration in summer (defined as June through October).…”

Section: Discussionmentioning

confidence: 99%

“…Legaard and Thomas [2006] examined seasonal and interannual variability in daily sea surface temperature (SST) and surface chlorophyll over the period 1997-2003 for a study area extending from southern California to northern Vancouver Island. Legaard and Thomas [2007] extended this study to include interdecadal variability, Thomas et al [2013] examined long-term trends, and Foukal and Thomas [2014] studied the seasonality of surface chlorophyll. Results show that surface chlorophyll values are highest from June through October in the coastal waters between northern Vancouver Island and Point Conception [Foukal and Thomas, 2014] and that surface chlorophyll in this general region has increased by about 0.1 mg m 23 per decade [Thomas et al, 2013].…”

Section: Introductionmentioning

confidence: 99%

“…Legaard and Thomas [2007] extended this study to include interdecadal variability, Thomas et al [2013] examined long-term trends, and Foukal and Thomas [2014] studied the seasonality of surface chlorophyll. Results show that surface chlorophyll values are highest from June through October in the coastal waters between northern Vancouver Island and Point Conception [Foukal and Thomas, 2014] and that surface chlorophyll in this general region has increased by about 0.1 mg m 23 per decade [Thomas et al, 2013]. Interannual variability is dominated by the El Niño-La Niña cycle [Legaard and Thomas, 2007].…”

Section: Introductionmentioning

confidence: 99%

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Satellite chlorophyll off the British Columbia Coast, 1997-2010

Jackson

Thomson

Brown

et al. 2015

J. Geophys. Res. Oceans

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We examine the spatial and temporal variability of satellite-sensed sea surface chlorophyll off the west coast of North America from 1997 to 2010, with focus on coastal British Columbia. The variability in surface chlorophyll is complex. Whereas the spring bloom generates the highest phytoplankton concentration for coastal Alaska, the north and east coasts of Haida Gwaii, Queen Charlotte Sound, the Strait of Georgia, and coastal Oregon and California, it is the fall bloom that normally generates the highest concentration for the west coast of Vancouver Island, Juan de Fuca Strait, and the west coast of Washington. The highest satellite-sensed chlorophyll concentrations occur in the Strait of Georgia, where mean values are at least 2 times higher than elsewhere in the northeast Pacific. Moreover, the annual average surface chlorophyll concentration increased significantly in the Strait of Georgia during this period, with highest concentration observed during the near neutral ENSO conditions of the spring of 2007. The next highest concentrations occur off southwest Vancouver Island but have no statistically significant trend. The lowest average peak chlorophyll concentration is observed off Southern California. The timing of the highest chlorophyll concentration is latest off the coast of Washington and earliest off the coast of Southern California. Small increasing concentration trends are observed off the Washington and California coasts.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Satellite chlorophyll off the British Columbia Coast, 1997-2010

Jackson

Thomson

Brown

et al. 2015

J. Geophys. Res. Oceans

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“…High temporal and spatial resolution of satellite time series data are required to reduce uncertainty in the estimation of phenological indexes [e.g., Foukal and Thomas , ]. This is especially important for the region off central‐southern Chile since: (a) the interannual differences in ZET indexes are of the order of ∼15–30 days [ Montecinos and Gomez , ], and (b) the annual cycle of Chl‐a in the coastal zone displays a complex pattern, associated with variations in coastline orientation and bathymetry [ Correa‐Ramirez et al ., ; Morales et al ., ].…”

Section: Methodsmentioning

confidence: 99%

Phytoplankton phenology in the coastal upwelling region off central‐southern Chile (35°S–38°S): Time‐space variability, coupling to environmental factors, and sources of uncertainty in the estimates

et al. 2015

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The annual cycle and phenology of phytoplankton (satellite-derived chlorophyll-a, Chl-a) in the coastal upwelling region off central-southern Chile, their time-space variation, the extent of their coupling with those of wind-driven upwelling (as Zonal Ekman Transport, ZET), Sea Surface Temperature (SST), and Photosynthetically Active Radiation (PAR) were analyzed using a 10 year satellite time series (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012). Wavelet analysis (WA) was applied to extract the dominant frequencies of variability and their recurrence, to derive the phenological indexes, and to assess the extent of the coupling between Chl-a and environmental forcing in the annual frequency. Index estimates were obtained from minimum and maximum accumulated values in two different frequency bands, annual (WA-ANF) and all except the synoptic (WA-ALF). The annual frequency was dominant in all the variables; however, the annual cycle and phenology of Chl-a displayed higher submeso and mesoscale variability. The mean onset date of Chl-a was similar to those of PAR and ZET with WA-ALF and cross WA indicated that, for the most part, their annual cycles were coupled or coherent. Few interannual changes in Chl-a phenology were detected, including a 1 month longer duration (WA-ALF) during La Niña 2010-2011. The mean anomalies in the magnitudes of Chl-a and ZET during the upwelling season showed a slight but significant trend, negative for Chl-a and positive for ZET, while SST remained relatively constant. This pattern was unexpected since three La Niña-related conditions were identified during the 2007-2012 period.

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“…Ecological explanations for the presence of individual PFTs include the following: (1) coastal upwelling events, (2) seasonal freshwater fluxes from major estuaries or rivers, (3) variability in the intensity of fall and winter storms which reduce/enhance mixing-induced vertical nutrient fluxes resulting in decreased/increased chlorophyll a levels in fall/winter, and, (4) stronger than usual wind stress curl in the summer, which can shoal the thermocline offshore and deliver nutrients to the upper photic zone, producing local phytoplankton blooms (Foukal and Thomas, 2014). One-dimensional models have proven helpful in revealing the underlying mechanisms driving the phenological shifts in the phytoplankton community when local forcing controls the mixing/stratification dynamics (Olivieri and Chavez, 2000).…”

Section: Marker Pigmentmentioning

confidence: 99%

Satellite Observations of Phytoplankton Functional Type Spatial Distributions, Phenology, Diversity, and Ecotones

et al. 2017

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Phytoplankton functional diversity plays a key role in structuring the ocean carbon cycle and can be estimated using measurements of phytoplankton functional type (PFT) groupings. Concentrations of 18 phytoplankton pigments were calculated using a linear matrix inversion algorithm, with an average r 2 value of 0.70 for all pigments with p-values below the statistical threshold of 0.05. The inversion algorithm was then used with a chlorophyll-based absorption spectra model and Moderate Resolution Imaging Spectroradiometer (MODIS-Aqua) chlorophyll observations to calculate phytoplankton pigment concentrations in an area of the Atlantic Ocean off the United States east coast. Pigment distributions were analyzed to assess the distribution of PFTs. Five unique PFTs were found and delineated into three distinct offshore, transition, and open ocean groups. Group 1 (Diatoms) had highest abundance along the coast. Group 2 (prymnesiophytes, prokaryotes, and green algae) was a year-round stable offshore community that extended at reduced levels into the coast. Group 3 (dinoflagellates) dominated offshore between the Groups 1 and 2. Phytoplankton communities were delineated into coastal and offshore populations, with Group 2 having a dampened seasonal cycle, relative to the coastal populations. Shannon Diversity Indices (H) for the PFTs showed both spatial and temporal variability and had a clear non-linear relationship with chlorophyll. Diversity levels varied seasonally with changes in chlorophyll a levels. Peak PFT H was observed on the shelf where frontal features dominate, with diversity levels declining nearshore and offshore. This region marks an ecotone for phytoplankton in the study domain, and is associated with the coastal-side boundary of dinoflagellate dominance. Highest levels of diversity were observed in the tidally well-mixed regions of the Gulf of Maine and along a band that ran along the shelf region of the study area that was narrowest in the summer periods and broadened during the winter. These peak diversity zones were associated with moderate levels (∼0.8 mg m −3 ) of chlorophyll a. While the sign in the linear trends in chlorophyll between 2002 and 2016 varied depending on the region, the trends in the PFT H values were nearly all negative due to the non-linear relationship between chlorophyll levels and H.

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Biogeography and phenology of satellite-measured phytoplankton seasonality in the California current

Cited by 24 publications

References 76 publications

Satellite chlorophyll off the British Columbia Coast, 1997-2010

Satellite chlorophyll off the British Columbia Coast, 1997-2010

Phytoplankton phenology in the coastal upwelling region off central‐southern Chile (35°S–38°S): Time‐space variability, coupling to environmental factors, and sources of uncertainty in the estimates

Satellite Observations of Phytoplankton Functional Type Spatial Distributions, Phenology, Diversity, and Ecotones

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