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| Author | Kelly, T.B.; Goericke, R.; Kahru, M.; Song, H.; Stukel, M.R. | ||||
| Title | CCE II: Spatial and interannual variability in export efficiency and the biological pump in an eastern boundary current upwelling system with substantial lateral advection | Type | $loc['typeJournal Article'] | ||
| Year | 2018 | Publication | Deep Sea Research Part I: Oceanographic Research Papers | Abbreviated Journal | Deep Sea Research Part I: Oceanographic Research Papers |
| Volume | 140 | Issue | Pages | 14-25 | |
| Keywords | CALIFORNIA CURRENT ECOSYSTEM; OCEAN CARBON-CYCLE; COASTAL WATERS; FRONTAL ZONE; TIME-SERIES; FLUX; SINKING; SEA; PACIFIC; ZOOPLANKTON | ||||
| Abstract | Estimating interannual variability in carbon export is a key goal of many marine biogeochemical studies. However, due to variations in export mechanisms between regions, generalized models used to estimate global patterns in export often fail when used for intra-regional analysis. We present here a region-specific model of export production for the California Current Ecosystem (CCE) parameterized using intensive Lagrangian process studies conducted during El Niño-Southern Oscillation (ENSO) warm and neutral phases by the CCE Long-Term Ecological Research (LTER) program. We find that, contrary to expectations from prominent global algorithms, export efficiency (e-ratio = export / primary productivity) is positively correlated with temperature and negatively correlated with net primary productivity (NPP). We attribute these results to the substantial horizontal advection found within the region, and verify this assumption by using a Lagrangian particle tracking model to estimate water mass age. We further suggest that sinking particles in the CCE are comprised of a recently-produced, rapidly-sinking component (likely mesozooplankton fecal pellets) and a longer-lived, slowly-sinking component that is likely advected long distances prior to export. We determine a new algorithm for estimating particle export in the CCE from NPP (Export = 0.08 · NPP + 72 mg C m-2 d-1). We apply this algorithm to a two-decade long time series of NPP in the CCE to estimate spatial and interannual variability across multiple ENSO phases. Reduced export during the warm anomaly of 2014-2015 and El Niño 2015-2016 resulted primarily from decreased export in the coastal upwelling region of the CCE; the oligotrophic offshore region exhibited comparatively low seasonal and interannual variability in flux. The model resolves intra-regional patterns of in situ export measurements, and provides a valuable contrast to global export models. | ||||
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| ISSN | 0967-0637 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ rl18 @ | Serial | 984 | ||
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| Author | Kelly, T.B.; Goericke, R.; Kahru, M.; Song, H.; Stukel, M.R. | ||||
| Title | CCE II: Spatial and interannual variability in export efficiency and the biological pump in an eastern boundary current upwelling system with substantial lateral advection | Type | $loc['typeJournal Article'] | ||
| Year | 2018 | Publication | Deep Sea Research Part I: Oceanographic Research Papers | Abbreviated Journal | Deep Sea Research Part I: Oceanographic Research Papers |
| Volume | 140 | Issue | Pages | 14-25 | |
| Keywords | california current ecosystem; coastal waters; flux; frontal zone; ocean carbon-cycle; oceanography; pacific; sea; sinking; time-series; Zooplankton | ||||
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| ISSN | 0967-0637 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1022 | ||
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| Author | Samuelsen, A | ||||
| Title | Modeling the Effect of Eddies and Advection on the Lower Trophic Ecosystem in the Northeast Tropical Pacific | Type | $loc['typeManuscript'] | ||
| Year | 2005 | Publication | Abbreviated Journal | ||
| Volume | Issue | Pages | |||
| Keywords | Physical-Biological Interactions, Marine Ecosystem Modeling, Pacific Ocean, Gulf Of Tehuantepec, Costa Rica Dome, Cross-Shelf Transport, Eddies | ||||
| Abstract | A medium complexity, nitrogen-based ecosystem model is developed in order to simulate the ecosystem in the northeast tropical Pacific. Several physical processes have major impact on the ecosystem in this region, most importantly intense wind jets along the coast and upwelling at the Costa Rica Dome (CRD). The ecosystem model is run “offline”, using a realistic physical ocean model hindcast as input. The physical model is a subdomain of the global Navy Coastal Ocean Model, which is a hybrid sigma-z level model. The model assimilates Modular Ocean Data Assimilation System temperature and salinity profiles derived from altimetry and sea surface temperature data. The model is forced by daily heat and momentum fluxes, and therefore captures short-term wind events such as the Tehuantepec jet. Because the model has high horizontal resolution (~1/8 degree) and assimilates sea surface height data, it has a realistic representation of eddies and mesoscale variability. The ecosystem model includes two nutrients (nitrate and ammonium), two size-classes of phytoplankton, two size-classes of zooplankton, and detritus. The model is run for 4 years from 1999 to 2002, with analyses focused on 2000-2002. The model is validated using SeaWiFS data and ship-based observations from the STAR-cruises (Stenella Abundance Research Project) of 1999 and 2000. The northernmost and most intense of the wind jets along Central America is the Tehuantepec jet. The Tehuantepec jet is responsible for upwelling large amounts of nutrient rich water south of the Gulf of Tehuantepec. The jet also occasionally produce large anti-cyclonic eddies that transport organic matter away from the coast. Because organic matter that is transported into the open ocean will eventually sink to the deep ocean, this has implications for the carbon export in this region. The model results are used to calculate cross-shelf fluxes in this region in order to estimate how much organic material is transported across the shelf break. Results show that at the Gulf of Tehuantepec there is high offshore export of organic material, particularly during eddy generation events, but also in fall. The highest export is on the order of 10 Mg C per meter of coastline per day and happens during eddy events. During these events there is a comparable onshore flux to the south of the gulf. Typically there is onshore flux to the south of the gulf during the summer. The model estimated transport away from the coast at the Gulf of Tehuantepec is 167 Tg C/year, and the onshore transport to the south of the gulf is 704 Tg C/year. The second subject of interest is the CRD. In this region, upwelling at the surface is caused by Ekman upwelling during the summer, although the dome is thought to be present at depth throughout the year. The doming of the isotherms below the thermocline is a result of vortex stretching and is decoupled from the wind-driven processes at the surface. A mass-balance budget is calculated at the CRD, and the horizontal and vertical fluxes are related to the abundance of plankton at the dome. There is upwelling (7.2X10-2 Sv ) at the dome throughout the year, but around the location of the dome (90° W), the upwelling is largest in the winter. Further west, input of nutrients from below is larger in the fall and summer. The results suggest that about 80% of the nitrate that is supplied to the dome during summer is actually brought up to the west of the dome and transported eastward by the North Equatorial Counter Current. | ||||
| Address | Department of Oceanography | ||||
| Corporate Author | Thesis | $loc['Ph.D. thesis'] | |||
| Publisher | Florida State University | Place of Publication | Tallahassee, FL | Editor | |
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| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ mfield @ | Serial | 591 | ||
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| Author | Stukel, M.R.; Decima, M.; Kelly, T.B. | ||||
| Title | A new approach for incorporating 15N isotopic data into linear inverse ecosystem models with Markov Chain Monte Carlo sampling | Type | $loc['typeJournal Article'] | ||
| Year | 2018 | Publication | PloS one | Abbreviated Journal | PLoS One |
| Volume | 13 | Issue | 6 | Pages | e0199123 |
| Keywords | Isotopic data; Nitrogen-based ecosystem models; Phytoplankton; Defecation by grazers; Mortality by phytoplankton | ||||
| Abstract | Oceanographic field programs often use delta15N biogeochemical measurements and in situ rate measurements to investigate nitrogen cycling and planktonic ecosystem structure. However, integrative modeling approaches capable of synthesizing these distinct measurement types are lacking. We develop a novel approach for incorporating delta15N isotopic data into existing Markov Chain Monte Carlo (MCMC) random walk methods for solving linear inverse ecosystem models. We test the ability of this approach to recover food web indices (nitrate uptake, nitrogen fixation, zooplankton trophic level, and secondary production) derived from forward models simulating the planktonic ecosystems of the California Current and Amazon River Plume. We show that the MCMC with delta15N approach typically does a better job of recovering ecosystem structure than the standard MCMC or L2 minimum norm (L2MN) approaches, and also outperforms an L2MN with delta15N approach. Furthermore, we find that the MCMC with delta15N approach is robust to the removal of input equations and hence is well suited to typical pelagic ecosystem studies for which the system is usually vastly under-constrained. Our approach is easily extendable for use with delta13C isotopic measurements or variable carbon:nitrogen stoichiometry. | ||||
| Address | Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL, United States of America | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 1932-6203 | ISBN | Medium | ||
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| Funding | strtoupper('2').strtolower('9912928'); strtoupper('P').strtolower('MC6005467') | Approved | $loc['no'] | ||
| Call Number | COAPS @ user @ | Serial | 975 | ||
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| Author | Stukel, M.R.; Décima, M.; Landry, M.R.; Selph, K.E. | ||||
| Title | Nitrogen and isotope flows through the Costa Rica Dome upwelling ecosystem: The crucial mesozooplankton role in export flux | Type | $loc['typeJournal Article'] | ||
| Year | 2018 | Publication | Global Biogeochemical Cycles | Abbreviated Journal | Global Biogeochemical Cycles |
| Volume | 32 | Issue | 12 | Pages | 1815–1832. |
| Keywords | Crustaceans; Diel vertical migration; Nitrogen cycle; Biological carbon pump; Nitrogen isotopes; Linear inverse ecosystem model | ||||
| Abstract | The Costa Rica Dome (CRD) is an open-ocean upwelling ecosystem, with high biomasses of picophytoplankton (especially Synechococcus), mesozooplankton, and higher trophic levels. To elucidate the food web pathways supporting the trophic structure and carbon export in this unique ecosystem, we used Markov Chain Monte Carlo techniques to assimilate data from four independent realizations of δ15N and planktonic rate measurements from the CRD into steady state, multicompartment ecosystem box models (linear inverse models). Model results present well-constrained snapshots of ecosystem nitrogen and stable isotope fluxes. New production is supported by upwelled nitrate, not nitrogen fixation. Protistivory (rather than herbivory) was the most important feeding mode for mesozooplankton, which rely heavily on microzooplankton prey. Mesozooplankton play a central role in vertical nitrogen export, primarily through active transport of nitrogen consumed in the surface layer and excreted at depth, which comprised an average 36-46% of total export. Detritus or aggregate feeding is also an important mode of resource acquisition by mesozooplankton and regeneration of nutrients within the euphotic zone. As a consequence, the ratio of passively sinking particle export to phytoplankton production is very low in the CRD. Comparisons to similar models constrained with data from the nearby equatorial Pacific demonstrate that the dominant role of vertical migrators to the biological pump is a unique feature of the CRD. However, both regions show efficient nitrogen transfer from mesozooplankton to higher trophic levels (as expected for regions with large fish, cetacean, and seabird populations) despite the dominance of protists as major grazers of phytoplankton. | ||||
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| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ rl18 @ | Serial | 978 | ||
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| Author | Wang, S.; Kranz, S.A.; Kelly, T.B.; Song, H.; Stukel, M.R.; Cassar, N. | ||||
| Title | Lagrangian Studies of Net Community Production: The Effect of Diel and Multiday Nonsteady State Factors and Vertical Fluxes on O2/Ar in a Dynamic Upwelling Region | Type | $loc['typeJournal Article'] | ||
| Year | 2020 | Publication | Journal of Geophysical Research: Biogeosciences | Abbreviated Journal | J. Geophys. Res. Biogeosci. |
| Volume | 125 | Issue | 6 | Pages | e2019JG005569 |
| Keywords | net community production; O2/Ar; California Current Ecosystem; Lagrangian measurements; vertical fluxes; nonsteady state | ||||
| Abstract | The ratio of dissolved oxygen to argon in seawater is frequently employed to estimate rates of net community production (NCP) in the oceanic mixed layer. The in situ O2/Ar‐based method accounts for many physical factors that influence oxygen concentrations, permitting isolation of the biological oxygen signal produced by the balance of photosynthesis and respiration. However, this technique traditionally relies upon several assumptions when calculating the mixed‐layer O2/Ar budget, most notably the absence of vertical fluxes of O2/Ar and the principle that the air‐sea gas exchange of biological oxygen closely approximates net productivity rates. Employing a Lagrangian study design and leveraging data outputs from a regional physical oceanographic model, we conducted in situ measurements of O2/Ar in the California Current Ecosystem in spring 2016 and summer 2017 to evaluate these assumptions within a �worst‐case� field environment. Quantifying vertical fluxes, incorporating nonsteady state changes in O2/Ar, and comparing NCP estimates evaluated over several day versus longer timescales, we find differences in NCP metrics calculated over different time intervals to be considerable, also observing significant potential effects from vertical fluxes, particularly advection. Additionally, we observe strong diel variability in O2/Ar and NCP rates at multiple stations. Our results reemphasize the importance of accounting for vertical fluxes when interpreting O2/Ar‐derived NCP data and the potentially large effect of nonsteady state conditions on NCP evaluated over shorter timescales. In addition, diel cycles in surface O2/Ar can also bias interpretation of NCP data based on local productivity and the time of day when measurements were made. | ||||
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| ISSN | 2169-8953 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1114 | ||
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| Author | Zeng, H.; Chambers, J.Q.; Negron-Juarez, R.I.; Hurtt, G.C.; Baker, D.B.; Powell, M.D. | ||||
| Title | Impacts of tropical cyclones on U.S. forest tree mortality and carbon flux from 1851 to 2000 | Type | $loc['typeJournal Article'] | ||
| Year | 2009 | Publication | Proceedings of the National Academy of Sciences of the United States of America | Abbreviated Journal | Proc Natl Acad Sci U S A |
| Volume | 106 | Issue | 19 | Pages | 7888-7892 |
| Keywords | Biodiversity; Biomass; Carbon; *Cyclonic Storms; Ecosystem; Greenhouse Effect; Models, Statistical; Southeastern United States; *Trees; United States | ||||
| Abstract | Tropical cyclones cause extensive tree mortality and damage to forested ecosystems. A number of patterns in tropical cyclone frequency and intensity have been identified. There exist, however, few studies on the dynamic impacts of historical tropical cyclones at a continental scale. Here, we synthesized field measurements, satellite image analyses, and empirical models to evaluate forest and carbon cycle impacts for historical tropical cyclones from 1851 to 2000 over the continental U.S. Results demonstrated an average of 97 million trees affected each year over the entire United States, with a 53-Tg annual biomass loss, and an average carbon release of 25 Tg y(-1). Over the period 1980-1990, released CO(2) potentially offset the carbon sink in forest trees by 9-18% over the entire United States. U.S. forests also experienced twice the impact before 1900 than after 1900 because of more active tropical cyclones and a larger extent of forested areas. Forest impacts were primarily located in Gulf Coast areas, particularly southern Texas and Louisiana and south Florida, while significant impacts also occurred in eastern North Carolina. Results serve as an important baseline for evaluating how potential future changes in hurricane frequency and intensity will impact forest tree mortality and carbon balance. | ||||
| Address | Department of Ecology and Evolutionary Biology, Tulane University, 400 Boggs Center, New Orleans, LA 70118, USA. hzeng@tulane.edu | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 0027-8424 | ISBN | Medium | ||
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| Funding | PMID:19416842; PMCID:PMC2683102 | Approved | $loc['no'] | ||
| Call Number | COAPS @ mfield @ | Serial | 658 | ||
| Permanent link to this record | |||||
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