A coupled physical-biological model of the Northern Gulf of Mexico shelf: model description, validation and analysis of phytoplankton variability

Fennel, Katja; Hetland, Robert D.; Feng, Yang; DiMarco, Steven F.

doi:10.5194/bg-8-1881-2011

Cited by 140 publications

(227 citation statements)

References 38 publications

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“…The details of how wind controls the spatial and temporal distribution of freshwater and bottom oxygen concentration on the Louisiana shelf has been addressed by Feng [2012]. We provide an example in the auxiliary material, in the context of a couple physical-biological circulation numerical model [Fennel et al, 2011;Hetland and DiMarco, 2012], of the MAR plume forced by a persistent upwelling-favorable wind during 2009 summer.…”

Section: Discussionmentioning

confidence: 99%

Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico

Feng¹,

DiMarco

Jackson

2012

Geophysical Research Letters

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[1] Seasonal hypoxia of the northern Gulf of Mexico has been observed for more than 25 years. It is generally accepted that the variation in the areal extent of hypoxia is determined by changes in nutrient addition from the Mississippi River. In this study, we investigate the statistical relation between the hypoxic area and a new variable, the duration of west wind, using the available measurements for the period 1985-2010. Special consideration was paid to the 1993-2010 period, a time when a large shift in the seasonal hypoxia pattern has been reported. When excluding the years in which hurricanes directly impacted the hypoxic area observation, we find that the duration of west wind is correlated with the hypoxic area at r 2 = 0.32 for the 1985-2010 period, and r 2 = 0.52 for the 1993-2010 period. Multilinear regressions using both wind duration and May-June nitrate loading improve the statistical relationships for both periods to r 2 = 0.69 and 0.74 for the long and short time periods, respectively. Mechanistically, the statistical relationships reflect the movement and changes in horizontal river plume position associated with the wind and the influence of stratification on the hypoxic area. Citation: Feng, Y., S. F. DiMarco, and G. A.Jackson (2012), Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico, Geophys. Res. Lett., 39, L09601,

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Section: Discussionmentioning

confidence: 99%

Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico

Feng¹,

DiMarco

Jackson

2012

Geophysical Research Letters

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“…Processes 1, 3, 9, and 12 follow Fennel et al (2006Fennel et al ( , 2011 formulations, while processes 2, 4-8, and 10-11 follow Kishi et al (2007) formulations. Descriptions of the model equations and parameters are included in the Supplement.…”

Section: Model Descriptionmentioning

confidence: 99%

“…Xue et al (2013) configured Fennel's model for the entire GoM, describing main spatiotemporal patterns in plankton biomass and DIN in the coastal and oceanic domains. However, since they did not investigate underlying drivers (production, biomass losses) of phytoplankton biomass as was done in Fennel et al (2011), less is known about the factors modulating the seasonality of phytoplankton in the deep GoM.…”

Section: Introductionmentioning

confidence: 99%

“…The original Fennel's model formulation included ammonium, nitrate, phytoplankton, chlorophyll, zooplankton (representing mesozooplankton), and two detritus types as state variables. Fennel et al (2011) examined the underlying factors determining seasonal patterns in phytoplankton biomass in the LouisianaTexas shelf and concluded that phytoplankton production was not nitrogen limited near the MS delta. They also showed that zooplankton grazing played an important role in defining phytoplankton biomass changes and speculated that physical transport of phytoplankton could impact biomass seasonality.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal patterns in phytoplankton biomass across the northern and deep Gulf of Mexico: a numerical model study

et al. 2018

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Abstract. Biogeochemical models that simulate realistic lower-trophic-level dynamics, including the representation of main phytoplankton and zooplankton functional groups, are valuable tools for improving our understanding of natural and anthropogenic disturbances in marine ecosystems. Previous three-dimensional biogeochemical modeling studies in the northern and deep Gulf of Mexico (GoM) have used only one phytoplankton and one zooplankton type. To advance our modeling capability of the GoM ecosystem and to investigate the dominant spatial and seasonal patterns of phytoplankton biomass, we configured a 13-component biogeochemical model that explicitly represents nanophytoplankton, diatoms, micro-, and mesozooplankton. Our model outputs compare reasonably well with observed patterns in chlorophyll, primary production, and nutrients over the Louisiana-Texas shelf and deep GoM region. Our model suggests silica limitation of diatom growth in the deep GoM during winter and near the Mississippi delta during spring. Model nanophytoplankton growth is weakly nutrient limited in the Mississippi delta year-round and strongly nutrient limited in the deep GoM during summer. Our examination of primary production and net phytoplankton growth from the model indicates that the biomass losses, mainly due to zooplankton grazing, play an important role in modulating the simulated seasonal biomass patterns of nanophytoplankton and diatoms. Our analysis further shows that the dominant physical process influencing the local rate of change of model phytoplankton is horizontal advection in the northern shelf and vertical mixing in the deep GoM. This study highlights the need for an integrated analysis of biologically and physically driven biomass fluxes to better understand phytoplankton biomass phenologies in the GoM.

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“…These studies have led to an improved understanding of the relationships between nutrient availability and biogeochemical processes such as photosynthesis and remineralization in all aquatic systems. Redfield stoichiometric ratios have been applied in coastal ocean biogeochemical models in the northern Gulf of Mexico (Fennel et al, 2011;Green et al, 2006Green et al, , 2008, and used in linking river nutrient loading with sea surface partial pressure of carbon dioxide (Gypens et al, 2004) and ocean acidification (Borges and Gypens, 2010). These studies have widely assumed that the dissolved inorganic carbon (DIC) uptake and nitrogen removal ratio in the water column follows the Redfield value (i.e.…”

Section: Introductionmentioning

confidence: 99%

The stoichiometry of inorganic carbon and nutrient removal in the Mississippi River plume and adjacent continental shelf

et al. 2012

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Abstract. The stoichiometry of dissolved inorganic carbon (DIC) and nutrients during biological uptake is widely assumed to follow the Redfield ratios (especially the C / N ratio) in large river plume ecosystems. However, this assumption has not been systematically examined and documented, because DIC and nutrients are rarely studied simultaneously in river plume areas and interpretation of ratios can be confounded by strong river-ocean mixing as well as intense biological activity. We examined stoichiometric ratios of DIC and nutrients (NO and calculated biological removal as the difference between observed concentrations and those predicted from conservative mixing, as determined from a multi-endmember mixing model and observed salinity and total alkalinity. Despite complex physical and biogeochemical influences, relationships between DIC and nutrients were strongly dependent on salinity range and geographic location, and influenced by biological removal. Lower C / Si and N / Si ratios in one nearshore area were likely due to localized input of high Si and low NO − 3 water from adjacent wetlands or preferential removal of nitrogen in the area. When net biological uptake was separated from river-ocean mixing and corrected for preferential N removal, the stoichiometric ratio of C / N / Si was similar to the Redfield ratio, thus supporting the applicability of the Redfield-type C / N / Si ratios in river-plume biogeochemical models.

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A coupled physical-biological model of the Northern Gulf of Mexico shelf: model description, validation and analysis of phytoplankton variability

Cited by 140 publications

References 38 publications

Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico

Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico

Seasonal patterns in phytoplankton biomass across the northern and deep Gulf of Mexico: a numerical model study

The stoichiometry of inorganic carbon and nutrient removal in the Mississippi River plume and adjacent continental shelf

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