scholarly journals Quantifying spatiotemporal variability in zooplankton dynamics in the Gulf of Mexico with a physical-biogeochemical model

2019 ◽  
Author(s):  
Taylor A. Shropshire ◽  
Steven L. Morey ◽  
Eric P. Chassignet ◽  
Alexandra Bozec ◽  
Victoria J. Coles ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Net Primary Production ◽  
Spatiotemporal Variability ◽  
Biogeochemical Model ◽  
Zooplankton Abundance ◽  
Mesozooplankton Biomass ◽  
Biogeochemical Models ◽  
Zooplankton Dynamics ◽  
Remote Sensing Techniques ◽  
Specific Growth Rates

Abstract. Zooplankton play an important role in global biogeochemistry and their secondary production supports valuable fisheries of the world's oceans. Currently, zooplankton abundances cannot be estimated using remote sensing techniques. Hence, coupled physical-biogeochemical models (PBMs) provide an important tool for studying zooplankton on regional and global scales. However, evaluating the accuracy of zooplankton abundance estimates from PBMs has been a major challenge as a result of sparse observations. In this study, we configure a PBM for the Gulf of Mexico (GoM) from 1993–2012 and validate the model against an extensive combination of in situ biomass and rate measurements including total mesozooplankton biomass, size-fractionated mesozooplankton biomass and grazing rates, microzooplankton specific grazing rates, surface chlorophyll, deep chlorophyll maximum depth, phytoplankton specific growth rates, and net primary production. Spatial variability in mesozooplankton biomass climatology observed in a multi-decadal database for the northern GoM is well resolved by the model with a statistically significant (p 

scholarly journals Quantifying spatiotemporal variability in zooplankton dynamics in the Gulf of Mexico with a physical–biogeochemical model

2020 ◽  
Vol 17 (13) ◽  
pp. 3385-3407 ◽  
Author(s):  
Taylor A. Shropshire ◽  
Steven L. Morey ◽  
Eric P. Chassignet ◽  
Alexandra Bozec ◽  
Victoria J. Coles ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Secondary Production ◽  
Food Source ◽  
Net Primary Production ◽  
Zooplankton Biomass ◽  
Spatiotemporal Variability ◽  
Biogeochemical Model ◽  
Feeding Mode ◽  
Mesozooplankton Biomass ◽  
Biogeochemical Models

Abstract. Zooplankton play an important role in global biogeochemistry, and their secondary production supports valuable fisheries of the world's oceans. Currently, zooplankton standing stocks cannot be estimated using remote sensing techniques. Hence, coupled physical–biogeochemical models (PBMs) provide an important tool for studying zooplankton on regional and global scales. However, evaluating the accuracy of zooplankton biomass estimates from PBMs has been a major challenge due to sparse observations. In this study, we configure a PBM for the Gulf of Mexico (GoM) from 1993 to 2012 and validate the model against an extensive combination of biomass and rate measurements. Spatial variability in a multidecadal database of mesozooplankton biomass for the northern GoM is well resolved by the model with a statistically significant (p < 0.01) correlation of 0.90. Mesozooplankton secondary production for the region averaged 66±8×109 kg C yr−1, equivalent to ∼10 % of net primary production (NPP), and ranged from 51 to 82×109 kg C yr−1, with higher secondary production inside cyclonic eddies and substantially reduced secondary production in anticyclonic eddies. Model results from the shelf regions suggest that herbivory is the dominant feeding mode for small mesozooplankton (< 1 mm), whereas larger mesozooplankton are primarily carnivorous. In open-ocean oligotrophic waters, however, both mesozooplankton groups show proportionally greater reliance on heterotrophic protists as a food source. This highlights an important role of microbial and protistan food webs in sustaining mesozooplankton biomass in the GoM, which serves as the primary food source for early life stages of many commercially important fish species, including tuna.

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

2018 ◽  
Vol 15 (11) ◽  
pp. 3561-3576 ◽  
Author(s):  
Fabian A. Gomez ◽  
Sang-Ki Lee ◽  
Yanyun Liu ◽  
Frank J. Hernandez Jr. ◽  
Frank E. Muller-Karger ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Primary Production ◽  
Phytoplankton Biomass ◽  
Mississippi Delta ◽  
Three Dimensional ◽  
Rate Of Change ◽  
Integrated Analysis ◽  
Biogeochemical Model ◽  
Seasonal Patterns ◽  
Biogeochemical Models

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.

scholarly journals Seasonal Patterns in Phytoplankton Biomass across the Northern and Deep Gulf of Mexico: A Numerical Model Study

2017 ◽  
Author(s):  
Fabian A. Gomez ◽  
Sang-Ki Lee ◽  
Yanyun Liu ◽  
Frank J. Hernandez Jr. ◽  
Frank E. Muller-Karger ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Phytoplankton Biomass ◽  
Three Dimensional ◽  
Trophic Levels ◽  
Biogeochemical Model ◽  
Seasonal Patterns ◽  
Biogeochemical Models ◽  
Model Study ◽  
Numerical Model Study

Abstract. Biogeochemical models that simulate realistic lower trophic levels dynamics, including the representation of main phytoplankton and zooplankton functional groups, are valuable tools for our understanding of natural and anthropogenic disturbances in marine ecosystems. However, 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 phytoplankton biomass, we configured a 14-component biogeochemical model that explicitly represents nanophytoplankton, diatoms, micro-, and mesozooplankton. Our model outputs compare well with satellite and in situ observations, reproducing dominant seasonal patterns in chlorophyll and primary production. The model results show that diatom growth is strongly silica limited (> 95 %) in the deep GoM, and both nitrogen and silica limited (30–70 %) in the northern shelf. Nanophytoplankton growth is weakly nutrient limited in the Mississippi delta year-round (

scholarly journals Should we account for mesozooplankton reproduction and ontogenetic growth in biogeochemical modeling?

2021 ◽  
Author(s):  
Corentin Clerc ◽  
Olivier Aumont ◽  
Laurent Bopp
Keyword(s):  
Temporal Dynamics ◽  
Fecal Pellet ◽  
Ingestion Rate ◽  
Temporal Variations ◽  
Trophic Levels ◽  
Nutrient Concentrations ◽  
Biogeochemical Model ◽  
3 Dimensional ◽  
Mesozooplankton Biomass ◽  
Biogeochemical Models

AbstractMesozooplankton play a key role in marine ecosystems as they modulate the transfer of energy from phytoplankton to large marine organisms. In addition, they directly influence the oceanic cycles of carbon and nutrients through vertical migrations, fecal pellet production, respiration, and excretion. Mesozooplankton are mainly made up of metazoans, which undergo important size changes during their life cycle, resulting in significant variations in metabolic rates. However, most marine biogeochemical models represent mesozooplankton as protists-like organisms. Here, we study the potential caveats of this simplistic representation by using a chemostat-like zero-dimensional model with four different Nutrient-Phytoplankton-Zooplankton configurations in which the description of mesozooplankton ranges from protist-type organisms to using a size-based formulation including explicit reproduction and ontogenetic growth. We show that the size-based formulation strongly impacts mesozooplankton. First, it generates a delay of a few months in the response to an increase in food availability. Second, the increase in mesozooplankton biomass displays much larger temporal variations, in the form of successive cohorts, because of the dependency of the ingestion rate to body size. However, the size-based formulation does not affect smaller plankton or nutrient concentrations. A proper assessment of these top-down effects would require implementing our size-resolved approach in a 3-dimensional biogeochemical model. Furthermore, the bottom-up effects on higher trophic levels resulting from the significant changes in the temporal dynamics of mesozooplankton could be estimated in an end-to-end model coupling low and high trophic levels.

scholarly journals Downscaling CMIP6 Global Solutions to Regional Ocean Carbon Model: Connecting the Mississippi, Gulf of Mexico, and Global Ocean

2021 ◽  
Author(s):  
Le Zhang ◽  
Z. George Xue
Keyword(s):  
Gulf Of Mexico ◽  
Carbon Sink ◽  
Biological Activities ◽  
Global Ocean ◽  
Biogeochemical Model ◽  
Spatial And Temporal Patterns ◽  
Saturation State ◽  
Biogeochemical Models ◽  
Ocean Carbon ◽  
Carbon System

Abstract. Coupled physical-biogeochemical models can significantly reduce uncertainties in estimating the spatial and temporal patterns of the ocean carbon system. Challenges of applying a coupled physical-biogeochemical model in the regional ocean include the reasonable prescription of carbon model boundary conditions, lack of in situ observations, and the oversimplification of certain biogeochemical processes. In this study, we applied a coupled physical-biogeochemical model (Regional Ocean Modelling System, ROMS) to the Gulf of Mexico (GoM) and achieved an unprecedented 20-year high-resolution (5 km, 1/22°) hindcast covering the period of 2000–2019. The model’s biogeochemical cycle is driven by the Coupled Model Intercomparison Project 6-Community Earth System Model 2 products (CMIP6-CESM2) and incorporates the dynamics of dissolved organic carbon (DOC) pools as well as the formation and dissolution of carbonate minerals. Model outputs include generally interested carbon system variables, such as pCO2, pH, aragonite saturation state (ΩArag), calcite saturation state (ΩCalc), CO2 air-sea flux, carbon burial rate, etc. The model’s robustness is evaluated via extensive model-data comparison against buoy, remote sensing-based Machine Learning (ML) predictions, and ship-based measurements. Model results reveal that the GoM water has been experiencing an ~ 0.0016 yr−1 decrease in surface pH over the past two decades, accompanied by a ~ 1.66 µatm yr−1 increase in sea surface pCO2. The air-sea CO2 exchange estimation confirms that the river-dominated northern GoM is a substantial carbon sink. The open water of GoM, affected mainly by the thermal effect, is a carbon source during summer and a carbon sink for the rest of the year. Sensitivity experiments are conducted to evaluate the impacts from river inputs and the global ocean via model boundaries. Our results show that the coastal ocean carbon cycle is dominated by enormous carbon inputs from the Mississippi River and nutrient-stimulated biological activities, and the carbon system condition of the open ocean is primarily driven by inputs from the Caribbean Sea via Yucatan Channel.

scholarly journals A skill assessment of the biogeochemical model REcoM2 coupled to the finite element sea-ice ocean model (FESOM 1.3)

2014 ◽  
Vol 7 (4) ◽  
pp. 4153-4249
Author(s):  
V. Schourup-Kristensen ◽  
D. Sidorenko ◽  
D. A. Wolf-Gladrow ◽  
C. Völker
Keyword(s):  
Finite Element ◽  
Southern Ocean ◽  
Primary Production ◽  
Net Primary Production ◽  
Global Scale ◽  
Ocean Model ◽  
Biogeochemical Model ◽  
Biogeochemical Models ◽  
The Pacific ◽  
The Pacific Ocean

Abstract. In coupled ocean-biogeochemical models, the choice of numerical schemes in the ocean circulation component can have a large influence on the distribution of the biological tracers. Biogeochemical models are traditionally coupled to ocean general circulation models (OGCMs), which are based on dynamical cores employing quasi regular meshes, and therefore utilize limited spatial resolution in a global setting. An alternative approach is to use an unstructured-mesh ocean model, which allows variable mesh resolution. Here, we present initial results of a coupling between the Finite Element Sea-ice Ocean Model (FESOM) and the biogeochemical model REcoM2, with special focus on the Southern Ocean. Surface fields of nutrients, chlorophyll a and net primary production were compared to available data sets with focus on spatial distribution and seasonal cycle. The model produced realistic spatial distributions, especially regarding net primary production and chlorophyll a, whereas the iron concentration became too low in the Pacific Ocean. The modelled net primary production was 32.5 Pg C yr−1 and the export production 6.1 Pg C yr−1. This is lower than satellite-based estimates, mainly due to the excessive iron limitation in the Pacific along with too little coastal production. Overall, the model performed better in the Southern Ocean than on the global scale, though the assessment here is hindered by the lower availability of observations. The modelled net primary production was 3.1 Pg C yr−1 in the Southern Ocean and the export production 1.1 Pg C yr−1. All in all, the combination of a circulation model on an unstructured grid with an ocean biogeochemical model shows similar performance to other models at non-eddy-permitting resolution. It is well suited for studies of the Southern Ocean, but on the global scale deficiencies in the Pacific Ocean would have to be taken into account.

Zooplankton summer composition in the southern Gulf of Mexico with emphasis on salp and hyperiid amphipod assemblages

2020 ◽  
Vol 100 (5) ◽  
pp. 665-680
Author(s):  
Clara M. Hereu ◽  
Maria Clara Arteaga ◽  
Clara E. Galindo-Sánchez ◽  
Sharon Z. Herzka ◽  
Paola G. Batta-Lona ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Spatial And Temporal Variability ◽  
Amphipod Species ◽  
Zooplankton Abundance ◽  
Dominant Group ◽  
Symbiotic Relationships ◽  
The North ◽  
Zooplankton Dynamics ◽  
Southern Gulf Of Mexico ◽  
Yucatan Channel

AbstractMesoscale features within the Gulf of Mexico (GOM) are known to influence zooplankton dynamics. Here we describe the composition of the zooplankton assemblage off shelf during summer in relation to environmental conditions, with emphasis on hyperiid amphipods and salps. Zooplankton samples were collected in summer of 2015 and 2016 in the central and southern GOM and in the Yucatan Channel in 2015. Two anticyclonic gyres were present in the north and less intense coupled cyclonic-anticyclonic gyres in the south. Zooplankton abundances differed temporally and spatially. Copepods were the dominant group (>55% of total abundance), while several less abundant taxa contributed to inter-annual and spatial differences. Amphipods and salps comprised <3% and their abundances were positively correlated. Fifty-six hyperiid and 10 salp species were identified. The dominant amphipod species were: Lestrigonus bengalensis (summer 2015), Anchylomera blossevillei and Primno spp. juveniles (summer 2016). Dominant salp species were Ihlea punctata, Iasis cylindrica and Thalia spp. Lower salp and amphipod species richness and abundance were associated with anticyclonic structures. Spatial and temporal differences were partly associated with symbiotic relationships between the groups. This study supports previous evidence of high spatial and temporal variability in zooplankton abundance in off-shelf waters of the GOM.

Sign in / Sign up

Export Citation Format

Share Document