Spatial and temporal variability of phytoplankton biomass and community structure over the continental margin of the northeast Gulf of Mexico based on pigment analysis

Qian, Yongchang; Jochens, Ann E.; Kennicutt, Mahlon C.; Biggs, Douglas C.

doi:10.1016/s0278-4343(02)00173-5

Cited by 77 publications

(74 citation statements)

References 27 publications

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“…In spring, [CHL] surf decreases (mean values of 0.09 mg m −3 ), and a MLD deeper than the top of the DCM is only observed in 26 % of the profiles. The seasonal cycle of the [CHL] surf obtained from the float profiles is consistent with that reported using satellite measurements (Müller-Karger et al, 1991;Salmerón-García et al, 2011).…”

Section: Concerning [Chl]supporting

confidence: 87%

“…So it is not warranted to test this hypothesis, given the temporal resolution of our floats (two profiles per month from each float). In situ observations by Qian et al (2003) also suggested shifts in the surface phytoplankton community that could also account for changes in [CHL] surf .…”

Section: Concerning [Chl]mentioning

confidence: 92%

“…In addition to the standard conductivity-temperaturedepth (CTD) sensors mounted on typical Argo profiling floats (Roemmich et al, 2003), BOEM floats were also equipped with an ECO FLbbCD-AP2 sensor (WET Labs, Inc.). This sensor allowed the measurement of [CHL] and colored dissolved organic matter (CDOM) fluorescence, as well as the optical backscattering (bbp) at 700 nm (see Green et al, 2014 for more details).…”

Section: Apex Float Databasementioning

confidence: 99%

“…Other studies, mostly based on satellite surface chlorophyll measurements (Müller-Karger et al, 1991;Salmerón-García et al, 2011), or numerical simulations (Fennel et al, 2011;Walsh et al, 1989;Xue et al, 2013), suggest important seasonal variations. Lower [CHL] surf values are observed from May to July and maximum values are found in winter from December to February.…”

Section: Introductionmentioning

confidence: 99%

“…This cycle is considered to be primarily triggered by annual changes in ocean-atmosphere fluxes (Virmani and Weisberg, 2003), resulting in the deepening of the mixed layer in winter. In the GOM, it has been suggested that a higher [CHL] surf in winter occurs concomitantly with a biomass increase, as a consequence of nutrient entrainment at the surface (Jolliff et al, 2008;Melo González et al, 2000;Müller-Karger et al, 1991Salmerón-García et al, 2011). However, this has never been truly demonstrated due to the absence of sufficient data at the proper spatio-temporal scales in the water column.…”

Section: Introductionmentioning

confidence: 99%

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Temporal variability of chlorophyll distribution in the Gulf of Mexico: bio-optical data from profiling floats

et al. 2017

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Abstract. Chlorophyll concentration is a key oceanic biogeochemical variable. In the Gulf of Mexico (GOM), its distribution, which is mainly obtained from satellite surface observations and scarce in situ experiments, is still poorly understood. In 2011-2012, eight profiling floats equipped with biogeochemical sensors were deployed for the first time in the GOM and generated an unprecedented dataset that significantly increased the number of chlorophyll vertical distribution measurements in the region. The analysis of these data, once calibrated, permits us to reconsider the spatial and temporal variability of the chlorophyll concentration in the water column. At a seasonal scale, results confirm the surface signal seen by satellites, presenting maximum concentrations in winter and low values in summer. It is shown that the deepening of the mixed layer is the primary factor triggering the chlorophyll surface increase in winter. In the GOM, a possible interpretation is that this surface increase corresponds to a biomass increase. However, the present dataset suggests that the basin-scale climatological surface increase in chlorophyll content results from a vertical redistribution of subsurface chlorophyll and/or photoacclimation processes, rather than a net increase of biomass. One plausible explanation for this is the decoupling between the mixed-layer depth and the deep nutrient reservoir since mixed-layer depth only reaches the nitracline in sporadic events in the observations. Float measurements also provide evidence that the depth and the magnitude of the deep chlorophyll maximum is strongly controlled by the mesoscale variability, with higher chlorophyll biomass generally observed in cyclones rather than anticyclones.

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Section: Concerning [Chl]supporting

confidence: 87%

Section: Concerning [Chl]mentioning

confidence: 92%

Section: Apex Float Databasementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Temporal variability of chlorophyll distribution in the Gulf of Mexico: bio-optical data from profiling floats

et al. 2017

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Partitioning of the Open Waters of the Gulf of Mexico Based on the Seasonal and Interannual Variability of Chlorophyll Concentration

et al. 2018

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The seasonal and interannual variability of chlorophyll in the Gulf of Mexico open waters is studied using a three‐dimensional coupled physical‐biogeochemical model. A 5 years hindcast driven by realistic open‐boundary conditions, atmospheric forcings, and freshwater discharges from rivers is performed. The use of recent in situ observations allowed an in‐depth evaluation of the model nutrient and chlorophyll seasonal distributions, including the chlorophyll vertical structure. We find that different chlorophyll patterns of temporal variability coexist in the deep basin which thereby cannot be considered as a homogeneous region with respect to chlorophyll dynamics. A partitioning of the Gulf of Mexico open waters based on the winter chlorophyll concentration increase is then proposed. This partition is basically explained by the amount of nutrients injected into the euphotic layer which is highly constrained by the dynamic of the winter mixed layer. The seasonal and interannual variability appears to be affected by the variability of atmospheric fluxes and mesoscale dynamics (Loop Current eddies in particular). Finally, estimates of primary production in the deep basin are provided.

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Contrasting fine‐scale distributional patterns of zooplankton driven by the formation of a diatom‐dominated thin layer

Greer

Boyette

Cruz

et al. 2020

Limnology & Oceanography

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Although plankton thin layers have been described and modeled in a variety of environments, the physical structure surrounding the layer, associated biological rates, and distributions of multiple trophic levels are rarely examined simultaneously. Similar combinations of measurements, such as growth, mortality, and spatial relationships among plankton, are key to understanding how physical processes generating thin layers can influence abundances, composition, and predator‐prey interactions. An in situ imaging system was deployed along a southward‐oriented transect to describe the full ~ 2.3‐km extent of a thin layer arching from 8 to 4 m deep, with Chlorophyll a enhanced by an order of magnitude inside the layer (23.9 mg m−3 peak concentration). Physical oceanographic measurements, distributions of different plankton groups, and output from a high‐resolution model indicated that surface convergence and vertical shear drove the formation of the layer, which was dominated by Odontella sp. diatoms that were relatively scarce in the broader study region. Phytoplankton apparent growth (0.64 d−1) balanced microzooplankton grazing rates (0.52 d−1) within the layer, whereas grazing mortality (2.23 d−1) greatly exceeded phytoplankton growth (−0.39 d−1) outside the thin layer. Mesozooplankton had starkly differing distributions; copepods aggregated south of the layer near the surface, and doliolids followed the thin layer trajectory. A physical oceanographic model run over a 1‐month time period, including the time of sampling, indicated that similar surface convergences occurred frequently. Thin layers driven by convergence and shear may be common, with behavioral and buoyancy differences among plankton likely contributing to community structure and modification of trophic transfer.

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Spatial and temporal variability of phytoplankton biomass and community structure over the continental margin of the northeast Gulf of Mexico based on pigment analysis

Cited by 77 publications

References 27 publications

Temporal variability of chlorophyll distribution in the Gulf of Mexico: bio-optical data from profiling floats

Temporal variability of chlorophyll distribution in the Gulf of Mexico: bio-optical data from profiling floats

Partitioning of the Open Waters of the Gulf of Mexico Based on the Seasonal and Interannual Variability of Chlorophyll Concentration

Contrasting fine‐scale distributional patterns of zooplankton driven by the formation of a diatom‐dominated thin layer

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