Biogeochemical Modelling Research Papers - Academia.edu (original) (raw)

Zooplankton are the intermediate trophic level between phytoplankton and fish, and are an important component of carbon and nutrient cycles, accounting for a large proportion of the energy transfer to pelagic fishes and the deep ocean. Given zooplankton's importance, models need to adequately represent zooplankton dynamics. A major obstacle, though, is the lack of model assessment. Here we try and stimulate the assessment of zooplankton in models by filling three gaps. The first is that many zooplankton observationalists are unfamiliar with the biogeochemical, ecosystem, size-based and individual-based models that have zooplankton functional groups, so we describe their primary uses and how each typically represents zooplankton. The second gap is that many modelers are unaware of the zooplankton data that are available, and are unaccustomed to the different zooplankton sampling systems, so we describe the main sampling platforms and discuss their strengths and weaknesses for model assessment. Filling these gaps in our understanding of models and observations provides the necessary context to address the last gap—a blueprint for model assessment of zooplankton. We detail two ways that zooplankton biomass/abundance observations can be used to assess models: data wrangling that transforms observations to be more similar to model output; and observation models that transform model outputs to be more like observations. We hope that this review will encourage greater assessment of zooplankton in models and ultimately improve the representation of their dynamics.

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- Ecological Modelling, Biogeochemical Modelling, Zooplankton

The Cenomanian-Turonian oceanic anoxic event (OAE2) is characterized by large perturbations in the oxygen and sulfur cycles of the ocean, potentially resulting from changes in oxygen supply (via oxygen solubility and ocean circulation) and in marine productivity. We assess the relative impact of these mechanisms, comparing model experiments with a new compilation of observations for seafloor dysoxia/anoxia and photic-zone euxinia. The model employed is an intermediate-complexity Earth system model which accounts for the main ocean dynamics and biogeochemistry of the Cretaceous climate. The impact of higher temperature and marine productivity is evaluated in the model as a result of higher atmospheric carbon dioxide and oceanic nutrient concentrations. The model shows that temperature is not alone able to reproduce the observed patterns of oceanic redox changes associated with OAE2. Observations are reproduced in the model mainly via enhanced marine productivity due to higher nutrient content (responsible for 85% of the change). Higher phosphate content could have been sustained by increased chemical weathering and phosphorus regeneration from anoxic sediments, which in turn induced an enhanced nitrogen nutrient content of the ocean via nitrogen fixation. The model also shows that the presence of seafloor anoxia, as suggested by black-shale deposition in the proto-North Atlantic Ocean before the event, might be the result of the silled shape and lack of deep-water formation of this basin at the Late Cretaceous. Overall our model-data comparison shows that OAE2 anoxia was quasi-global spreading from 5% of the ocean volume before the event to at least 50% during OAE2.

- by Fanny Monteiro
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- Nutrient Cycling, Oceanic Anoxic Events, Cretaceous climate, Black shales

Cobalt is an important micronutrient for ocean microbes as it is present in vitamin B 12 and is a co-factor in various metalloenzymes that catalyze cellular processes. Moreover, when seawater availability of cobalt is compared to biological demands, cobalt emerges as being depleted in seawater, pointing to a potentially important limiting role. To properly account for the potential biological role for cobalt, there is therefore a need to understand the processes driving the biogeochemical cycling of cobalt and, in particular, the balance between external inputs and internal cycling. To do so, we developed the first cobalt model within a state-of-the-art three-dimensional global ocean biogeochemical model. Overall, our model does a good job in reproducing measurements with a correlation coefficient of >0.7 in the surface and >0.5 at depth. We find that continental margins are the dominant source of cobalt, with a crucial role played by supply under low bottom-water oxygen conditions. The basin-scale distribution of cobalt supplied from margins is facilitated by the activity of manganese-oxidizing bacteria being suppressed under low oxygen and low temperatures, which extends the residence time of cobalt. Overall, we find a residence time of 7 and 250 years in the upper 250 m and global ocean, respectively. Importantly, we find that the dominant internal resupply process switches from regeneration and recycling of particulate cobalt to dissolution of scavenged cobalt between the upper ocean and the ocean interior. Our model highlights key regions of the ocean where biological activity may be most sensitive to cobalt availability. Plain Language Summary Biological activity in the sea requires cobalt, primarily due to its role in vitamin B12 but also because it is required in other cellular enzymes. While our observations of cobalt distributions in the ocean is growing, we do not have a quantitative understanding of the role of different external sources of cobalt or how it is internally processed by different biological and chemical processes in the ocean. To answer these questions, we built the first ever global ocean cobalt model that coupled the cycling of cobalt to the major biogeochemical processes occurring in the ocean. Using this model, we identified that sediments are the major cobalt source and that the combination of oxygen levels and scavenging removal by bacteria allow externally supplied cobalt to pervade the ocean as a whole. We find that in certain regions of the upper ocean, cobalt levels may be low enough to affect biological activity but that to quantify this requires further work on how we represent cellular biochemistry.

- by Randelle Bundy
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- Biogeochemical Modelling, Cobalt, Biogeochemical Ocean Models, cobalt cycling

Mesoscale eddies in the south west Pacific region are prominent ocean features that represent distinctive environments for phytoplankton. Here, we examine the seasonal plankton dynamics associated with averaged cyclonic and anticyclonic eddies (CE and ACE, respectively) off eastern Australia. We do this through building seasonal climatologies of mixed layer depth (MLD) and surface chlorophyll-a for both CE and ACE by combining remotely sensed sea surface height (TOPEX/Poseidon, Envisat, Jason-1, and OSTM/Jason-2), remotely sensed ocean color (GlobColour) and in situ profiles of temperature, salinity and pressure from Argo floats. Using the CE and ACE seasonal climatologies, we assimilate the surface chlorophyll-a data into both a single (WOMBAT), and multi-phytoplankton class (EMS) biogeochemical model to investigate the level of complexity required to simulate the phytoplankton chlorophyll-a. For the two eddy types, the data assimilation showed both biogeochemical models only needed one set of parameters to represent phytoplankton but needed different parameters for zooplankton. To assess the simulated phytoplankton behavior we compared EMS model simulations with a ship-based experiment that involved incubating a winter phytoplankton community sampled from below the mixed layer under ambient and two higher light intensities with and without nutrient enrichment. By the end of the 5-day field experiment, large diatom abundance was four times greater in all treatments compared to the initial community, with a corresponding decline in pico-cyanobacteria. The experimental results were consistent with the simulated behavior in CE and ACE, where the seasonal deepening of the mixed layer during winter produced a rapid increase in large phytoplankton. Our model simulations suggest that CE off East Australia are not only characterized by a higher chlorophyll-a concentration compared to ACE, but also by a higher concentration of large phytoplankton (i.e., diatoms) due to the shallower CE mixed layer. The model simulations also suggest the zooplankton community is different in the two eddy types and this behavior needs further investigation.

- by Leonardo Laiolo and +2
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- Modelling, Phytoplankton, Biogeochemical Modelling, Mesoscale Eddies

In this paper a coupled physical–biogeochemical one-dimensional numerical model (BFM–POM 1D) was implemented in the Gulf of Trieste, (northern Adriatic Sea) and its structure was tested in order to evaluate its usability as a tool to support coastal management and planning. The evaluation concerned the ability of the model to reproduce the main trophic pathways, as well as their temporal variability, in terms of seasonal variations. The ecosystem structure comprised three phytoplankton groups, four zooplankton groups, one bacterial group, and a simple benthic return in order to parametrise benthic processes. The dynamics and interactions between groups were studied, as well as the model's sensitivity to different trophic web configurations. Results showed that the model was capable of replicating the behaviour of seasonal vertical profiles of the major biogeochemical elements, and the prevalence of the microbial food web shaping the trophic chain in the Gulf of Trieste. The model also responded to strong forcings at the surface and different trophic arrangements, thus providing initial evidence of its potential as a scientific tool aimed at marine coastal management.

- by Giulia Mussap and +1
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- Coastal Management, Ecosystem Modelling, Biogeochemical Modelling

The systematic literature search on the fertility rate was performed on articles from the Web of Science compiled by the Institute of Scientific Information (ISI) to provide major publication characteristics. All articles related to Fertility from year 1980 to 2011 were analyzed with the bibliometric approach using non-parametrics techniques. Total Citation, Citation per year and Cited References were significantly different between the 80's, 90's and 2000's, with more than a 100% increase in the number of publication. The association between number of authors and citation per year were significantly weak. Number of publication in a journal posed a poor negative association with the citation per year. Similarity between Authors Keyword and KeyWords Plus® do not promote the increase in citation per year. The author's affiliation and country of publication would be an interesting exploration for future fertility research. The bibiliometric analyses on Fertility is rather new and vital, as the key finding will provide researchers guidance in the literature search and future publication.

- by Review of Artificial Intelligence in Education and +1
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- Biochemistry, Evolutionary Biology, Social Demography, Health Psychology
- by Harini Santhanam
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- Remote Sensing, Water quality, Biogeochemical Modelling, Coastal

ABSTRACT 1-Training Course Parts
2-Theoretical Courses
2-1-Practical Part
2-2-Determination of Irgarol in coastal waters and sea Anemone tissues by GC-MS
2-2-1-Determination of Fatty acids in fish oil using GC-MS
2-2-2-Determination of Total mercury concentrations (HgT) in marine core sediment by DMA-80
2-2-3Oceanographic Survey (BANSIC 2014)
2-2-4-Workshops and Conferences
3-AWI-SAHFOS Summer School (Germany)
4-Advanced Oxidation and Bioremediation Treatment of Mercury in Marine Sediment
5-Outputs and Conclusion
6-Future Cooperation
7-References
8-Acknowledgement

- by Mohamed Hassaan
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- Biogeochemistry, Climate Change, Advanced Oxidation Processes, Bioremediation