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Lotze HK, Mellon S, Coyne J, Betts M, Burchell M, Fennel K, Dusseault MA, Fuller SD, Galbraith E, Garcia Suarez L, de Gelleke L, Golombek N, Kelly B, Kuehn SD, Oliver E, MacKinnon M, Muraoka W, Predham IT, Rutherford K, Shackell N, Sherwood O, Sibert EC, Kienast M. Long-term ocean and resource dynamics in a hotspot of climate change. Facets (Ott) 2022. [DOI: 10.1139/facets-2021-0197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The abundance, distribution, and size of marine species are linked to temperature and nutrient regimes and are profoundly affected by humans through exploitation and climate change. Yet little is known about long-term historical links between ocean environmental changes and resource abundance to provide context for current and potential future trends and inform conservation and management. We synthesize >4000 years of climate and marine ecosystem dynamics in a Northwest Atlantic region currently undergoing rapid changes, the Gulf of Maine and Scotian Shelf. This period spans the late Holocene cooling and recent warming and includes both Indigenous and European influence. We compare environmental records from instrumental, sedimentary, coral, and mollusk archives with ecological records from fossils, archaeological, historical, and modern data, and integrate future model projections of environmental and ecosystem changes. This multidisciplinary synthesis provides insight into multiple reference points and shifting baselines of environmental and ecosystem conditions, and projects a near-future departure from natural climate variability in 2028 for the Scotian Shelf and 2034 for the Gulf of Maine. Our work helps advancing integrative end-to-end modeling to improve the predictive capacity of ecosystem forecasts with climate change. Our results can be used to adjust marine conservation strategies and network planning and adapt ecosystem-based management with climate change.
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Affiliation(s)
- Heike K. Lotze
- Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Stefanie Mellon
- Department of Oceanography, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Jonathan Coyne
- Department of Oceanography, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Matthew Betts
- Canadian Museum of History, Gatineau, QC K1A 0M8, Canada
| | - Meghan Burchell
- Department of Archaeology, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | - Katja Fennel
- Department of Oceanography, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Marisa A. Dusseault
- Department of Archaeology, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | | | - Eric Galbraith
- Department of Earth and Planetary Sciences, McGill University, Montreal, QC H3A 0E8, Canada
- Institut de Ciència i Tecnologia Ambientals (ICTA-UAB), Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Lina Garcia Suarez
- Department of Oceanography, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Laura de Gelleke
- Department of Oceanography, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Nina Golombek
- Department of Earth and Environmental Sciences, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | | | - Sarah D. Kuehn
- Department of Archaeology, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | - Eric Oliver
- Department of Oceanography, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Megan MacKinnon
- Department of Archaeology, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | - Wendy Muraoka
- Department of Oceanography, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Ian T.G. Predham
- Department of Archaeology, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | - Krysten Rutherford
- Department of Oceanography, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Nancy Shackell
- Ocean and Ecosystem Sciences Division, Fisheries and Oceans Canada, Dartmouth, NS B3B 1J6, Canada
| | - Owen Sherwood
- Department of Earth and Environmental Sciences, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Elizabeth C. Sibert
- Department of Earth and Planetary Sciences, Yale University, PO Box 208109, New Haven, CT 06520, USA
- Yale Institute for Biospheric Studies, Yale University, 170 Whitney Avenue, New Haven, CT 06511, USA
| | - Markus Kienast
- Department of Oceanography, Dalhousie University, Halifax, NS B3H 4R2, Canada
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Matli VRR, Laurent A, Fennel K, Craig K, Krause J, Obenour DR. Fusion-Based Hypoxia Estimates: Combining Geostatistical and Mechanistic Models of Dissolved Oxygen Variability. Environ Sci Technol 2020; 54:13016-13025. [PMID: 32881494 DOI: 10.1021/acs.est.0c03655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The need to characterize and track coastal hypoxia has led to the development of geostatistical models based on in situ observations of dissolved oxygen (DO) and mechanistic models based on a representation of biophysical processes. To integrate the benefits of these two distinct modeling approaches, we develop a space-time geostatistical framework for synthesizing DO observations with hydrodynamic-biogeochemical model simulations and meteorological time series (as covariates). This fusion-based approach is used to estimate hypoxia in the northern Gulf of Mexico across summers from 1985 to 2017. Deterministic trends with dynamic covariates explain over 35% of the variability in DO. Moreover, cross-validation results indicate that 58% of DO variability is explained when combining these trends with spatiotemporal interpolation, which is substantially better than mechanistic or conventional geostatistical hypoxia modeling alone. The fusion-based approach also reduces hypoxic area uncertainties by 11% on average and up to 40% in months with sparse sampling. Moreover, our new estimates of mean summer hypoxic area changed by >10% in a majority of years, relative to previous geostatistical estimates. These fusion-based estimates can be a valuable resource when assessing the influence of hypoxia on the coastal ecosystem.
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Affiliation(s)
| | - Arnaud Laurent
- Department of Oceanography, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Katja Fennel
- Department of Oceanography, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Kevin Craig
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Beaufort, North Carolina 28516, United States
| | - Jacob Krause
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Beaufort, North Carolina 28516, United States
| | - Daniel R Obenour
- Center for Geospatial Analytics, NC State University, Raleigh, North Carolina 27695, United States
- Department of Civil, Construction and Environmental Engineering, NC State University, Raleigh, North Carolina 27695, United States
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Laurent A, Fennel K. Time-Evolving, Spatially Explicit Forecasts of the Northern Gulf of Mexico Hypoxic Zone. Environ Sci Technol 2019; 53:14449-14458. [PMID: 31738049 DOI: 10.1021/acs.est.9b05790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The Mississippi-Atchafalaya River Basin delivers large amounts of freshwater and nutrients to the northern Gulf of Mexico promoting the development of a large hypoxic zone every summer. Statistical and semiempirical models have long been used to provide seasonal forecasts of the mid-summer hypoxic extent using historic time series of spring nutrient load and mid-summer hypoxic extent. These forecasts consist of a scalar estimate of the hypoxic area with uncertainty but do not include spatial distributions or temporal evolution of hypoxic conditions. Three-dimensional (3D) circulation-biogeochemical models of the coastal ocean simulate the temporal evolution of hypoxia in a spatially explicit manner but have not yet been used for seasonal hypoxia forecasting. Here, we present a hybrid method for seasonal, spatially explicit, time-evolving forecasts of the hypoxic zone that combines statistical forecasting with information from a 3D biogeochemical model. The hybrid method uses spring nitrate load and a multiyear (1985-2018) 3D hindcast simulation to produce a seasonal forecast. Validation shows that the method explains up to 76% of the observed year-to-year variability in the hypoxic area. The forecasts suggest that the maximum seasonal extent of hypoxia is reached, on average, on August 13, 2 weeks after the completion of the annual cruise. An analysis of month-to-month variations in hypoxia forecasts due to variability in wind speed and freshwater discharge allows estimates of weather-related uncertainties in the forecast.
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Affiliation(s)
- Arnaud Laurent
- Department of Oceanography , Dalhousie University , Halifax B3H 4R2 , Nova Scotia , Canada
| | - Katja Fennel
- Department of Oceanography , Dalhousie University , Halifax B3H 4R2 , Nova Scotia , Canada
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Denley D, Metaxas A, Fennel K. Community composition influences the population growth and ecological impact of invasive species in response to climate change. Oecologia 2019; 189:537-548. [PMID: 30604087 DOI: 10.1007/s00442-018-04334-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 12/21/2018] [Indexed: 11/30/2022]
Abstract
Predicting long-term impacts of introduced species is challenging, since stressors related to global change can influence species-community interactions by affecting both demographic rates of invasive species and the structure of the invaded ecosystems. Invasive species can alter ecosystem structure over time, further complicating interactions between invasive species and invaded communities in response to additional stressors. Few studies have considered how cumulative impacts of species invasion and global change on the structure of invaded ecosystems may influence persistence and population growth of introduced species. Here, we present an empirically based population model for an invasive epiphytic bryozoan that can dramatically alter the structure of its invaded kelp bed ecosystems. We use this model to predict the response of invasive species to climate change and associated changes in the invaded community. Population growth of the bryozoan increased under near-future projections of increasing ocean temperature; however, the magnitude of population growth depended on the community composition of invaded kelp beds. Our results suggest that, in some cases, indirect effects of climate change mediated through changes to the structure of the invaded habitat can modulate direct effects of climate change on invasive species, with consequences for their long-term ecological impact. Our findings have important implications for management of invasive species, as modifying invaded habitats at local to regional scales may be more logistically feasible than addressing stressors related to global climate change.
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Affiliation(s)
- Danielle Denley
- Department of Oceanography, Dalhousie University, Halifax, NS, B3H 4R2, Canada.
| | - Anna Metaxas
- Department of Oceanography, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Katja Fennel
- Department of Oceanography, Dalhousie University, Halifax, NS, B3H 4R2, Canada
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5
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Abstract
Aquatic environments experiencing low-oxygen conditions have been described as hypoxic, suboxic, or anoxic zones; oxygen minimum zones; and, in the popular media, the misnomer "dead zones." This review aims to elucidate important aspects underlying oxygen depletion in diverse coastal systems and provides a synthesis of general relationships between hypoxia and its controlling factors. After presenting a generic overview of the first-order processes, we review system-specific characteristics for selected estuaries where adjacent human settlements contribute to high nutrient loads, river-dominated shelves that receive large inputs of fresh water and anthropogenic nutrients, and upwelling regions where a supply of nutrient-rich, low-oxygen waters generates oxygen minimum zones without direct anthropogenic influence. We propose a nondimensional number that relates the hypoxia timescale and water residence time to guide the cross-system comparison. Our analysis reveals the basic principles underlying hypoxia generation in coastal systems and provides a framework for discussing future changes.
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Affiliation(s)
- Katja Fennel
- Department of Oceanography, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada;
| | - Jeremy M Testa
- Chesapeake Biological Laboratory, University of Maryland Center for Environmental Studies, Solomons, Maryland 20688, USA;
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Claret M, Galbraith ED, Palter JB, Bianchi D, Fennel K, Gilbert D, Dunne JP. Rapid coastal deoxygenation due to ocean circulation shift in the NW Atlantic. Nat Clim Chang 2018; 8:866-872. [PMID: 30416585 PMCID: PMC6218011 DOI: 10.1038/s41558-018-0263-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 07/27/2018] [Indexed: 05/23/2023]
Abstract
Global observations show that the ocean lost approximately 2% of its oxygen inventory over the last five decades 1-3, with important implications for marine ecosystems 4, 5. The rate of change varies with northwest Atlantic coastal waters showing a long-term drop 6, 7 that vastly outpaces the global and North Atlantic basin mean deoxygenation rates 5, 8. However, past work has been unable to resolve mechanisms of large-scale climate forcing from local processes. Here, we use hydrographic evidence to show a Labrador Current retreat is playing a key role in the deoxygenation on the northwest Atlantic shelf. A high-resolution global coupled climate-biogeochemistry model 9 reproduces the observed decline of saturation oxygen concentrations in the region, driven by a retreat of the equatorward-flowing Labrador Current and an associated shift toward more oxygen-poor subtropical waters on the shelf. The dynamical changes underlying the shift in shelf water properties are correlated with a slowdown in the simulated Atlantic Meridional Overturning Circulation 10. Our results provide strong evidence that a major, centennial-scale change of the Labrador Current is underway, and highlight the potential for ocean dynamics to impact coastal deoxygenation over the coming century.
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Affiliation(s)
- Mariona Claret
- Joint Institute for the Study of the Atmosphere and the Ocean, Seattle, WA, USA
- University of Washington, Seattle, WA, USA
- Department of Earth and Planetary Sciences, McGill University, Montréal, QC, Canada
| | - Eric D Galbraith
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
- Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
- Department of Earth and Planetary Sciences, McGill University, Montréal, QC, Canada
| | - Jaime B Palter
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA
| | - Daniele Bianchi
- Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA, USA
| | - Katja Fennel
- Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Denis Gilbert
- Maurice Lamontagne Institute, Fisheries and Oceans Canada, Mont-Joli, QC, Canada
| | - John P Dunne
- NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ, USA
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Brennan CE, Blanchard H, Fennel K. Putting Temperature and Oxygen Thresholds of Marine Animals in Context of Environmental Change: A Regional Perspective for the Scotian Shelf and Gulf of St. Lawrence. PLoS One 2016; 11:e0167411. [PMID: 27997536 PMCID: PMC5172530 DOI: 10.1371/journal.pone.0167411] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 11/14/2016] [Indexed: 11/18/2022] Open
Abstract
We conducted a literature review of reported temperature, salinity, pH, depth and oxygen preferences and thresholds of important marine species found in the Gulf of St. Lawrence and Scotian Shelf region. We classified 54 identified fishes and macroinvertebrates as important either because they support a commercial fishery, have threatened or at risk status, or meet one of the following criteria: bycatch, baitfish, invasive, vagrant, important for ecosystem energy transfer, or predators or prey of the above species. The compiled data allow an assessment of species-level impacts including physiological stress and mortality given predictions of future ocean physical and biogeochemical conditions. If an observed, multi-decadal oxygen trend on the central Scotian Shelf continues, a number of species will lose favorable oxygen conditions, experience oxygen-stress, or disappear due to insufficient oxygen in the coming half-century. Projected regional trends and natural variability are both large, and natural variability will act to alternately amplify and dampen anthropogenic changes. When estimates of variability are included with the trend, species encounter unfavourable oxygen conditions decades sooner. Finally, temperature and oxygen thresholds of adult Atlantic wolffish (Anarhichas lupus) and adult Atlantic cod (Gadus morhua) are assessed in the context of a potential future scenario derived from high-resolution ocean models for the central Scotian Shelf.
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Affiliation(s)
- Catherine E. Brennan
- Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail:
| | - Hannah Blanchard
- Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Katja Fennel
- Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada
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Azhar MA, Canfield DE, Fennel K, Thamdrup B, Bjerrum CJ. A model-based insight into the coupling of nitrogen and sulfur cycles in a coastal upwelling system. J Geophys Res Biogeosci 2014; 119. [PMID: 26213661 PMCID: PMC4508913 DOI: 10.1002/2012jg002271] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The biogeochemical cycling in oxygen-minimum zones (OMZs) is dominated by the interactions of microbial nitrogen transformations and, as recently observed in the Chilean upwelling system, also through the energetically less favorable remineralization of sulfate reduction. The latter process is masked, however, by rapid sulfide oxidation, most likely through nitrate reduction. Thus, the cryptic sulfur cycle links with the nitrogen cycle in OMZ settings. Here, we model the physical-chemical water column structure and the observed process rates as driven by formation and sinking of organic detritus, to quantify the nitrogen and sulfur cycles in the Chilean OMZ. A new biogeochemical submodule was developed and coupled to the Regional Ocean Model System (ROMS). The model results generally agree with the observed distribution of reactive species and the measured process rates. Modeled heterotrophic nitrate reduction and sulfate reduction are responsible for 47% and 36%, respectively, of organic remineralization in a 150 m deep zone below mixed layer. Anammox contributes to 61% of the fixed nitrogen lost to N2 gas, while the rest of the loss is through canonical denitrification as a combination of organic matter oxidation by nitrite reduction and sulfide-driven denitrification. Mineralization coupled to heterotrophic nitrate reduction supplies ∼48% of the ammonium required by anammox. Due to active sulfate reduction, model results suggest that sulfide-driven denitrification contributes to 36% of the nitrogen loss as N2 gas. Our model results highlight the importance of considering the coupled nitrogen and sulfur cycle in examining open-ocean anoxic processes under present, past, and future conditions.
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Affiliation(s)
- Muchamad Al Azhar
- Nordic Center for Earth Evolution (NordCEE) and Department of Geosciences and Natural Resource Management, University of CopenhagenKøbenhavn K, Denmark
- Correspondence to: M. A. Azhar,
| | - Donald E Canfield
- Nordic Center for Earth Evolution (NordCEE) and Institute of Biology, University of Southern DenmarkOdense M, Denmark
| | - Katja Fennel
- Department of Oceanography, Dalhousie UniversityHalifax, Nova Scotia, Canada
| | - Bo Thamdrup
- Nordic Center for Earth Evolution (NordCEE) and Institute of Biology, University of Southern DenmarkOdense M, Denmark
| | - Christian J Bjerrum
- Nordic Center for Earth Evolution (NordCEE) and Department of Geosciences and Natural Resource Management, University of CopenhagenKøbenhavn K, Denmark
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Ibarra DA, Fennel K, Cullen JJ. Coupling 3-D Eulerian bio-physics (ROMS) with individual-based shellfish ecophysiology (SHELL-E): A hybrid model for carrying capacity and environmental impacts of bivalve aquaculture. Ecol Modell 2014. [DOI: 10.1016/j.ecolmodel.2013.10.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Hofmann EE, Cahill B, Fennel K, Friedrichs MAM, Hyde K, Lee C, Mannino A, Najjar RG, O'Reilly JE, Wilkin J, Xue J. Modeling the dynamics of continental shelf carbon. Ann Rev Mar Sci 2011; 3:93-122. [PMID: 21329200 DOI: 10.1146/annurev-marine-120709-142740] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Continental margin systems are important contributors to global nutrient and carbon budgets. Effort is needed to quantify this contribution and how it will be modified under changing patterns of climate and land use. Coupled models will be used to provide projections of future states of continental margin systems. Thus, it is appropriate to consider the limitations that impede the development of realistic models. Here, we provide an overview of the current state of modeling carbon cycling on continental margins as well as the processes and issues that provide the next challenges to such models. Our overview is done within the context of a coupled circulation-biogeochemical model developed for the northeastern North American continental shelf region. Particular choices of forcing and initial fields and process parameterizations are used to illustrate the consequences for simulated distributions, as revealed by comparisons to observations using quantitative statistical metrics.
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Affiliation(s)
- Eileen E Hofmann
- Center for Coastal Physical Oceanography, Old Dominion University, Norfolk, Virginia 23508, USA.
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12
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Mafra LL, Bricelj VM, Fennel K. Domoic acid uptake and elimination kinetics in oysters and mussels in relation to body size and anatomical distribution of toxin. Aquat Toxicol 2010; 100:17-29. [PMID: 20674991 DOI: 10.1016/j.aquatox.2010.07.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 06/14/2010] [Accepted: 07/01/2010] [Indexed: 05/29/2023]
Abstract
Toxin accumulation by suspension-feeding qualifier depends on a balance between processes regulating toxin uptake (i.e. ingestion and absorption of toxic cells) and elimination (i.e. egestion, exchange among tissues, excretion, degradation and/or biotransformation) during exposure to toxic blooms. This laboratory study compares the size-specific uptake and elimination kinetics of domoic acid (DA) from Pseudo-nitzschia multiseries in two co-occurring bivalves, the oyster Crassostrea virginica and the mussel Mytilus edulis. Domoic acid concentrations were measured in visceral and non-visceral tissues of different-sized oysters and mussels during simultaneous long-term exposure to toxic P. multiseries cells in the laboratory, followed by depuration on a non-toxic algal diet. Mussels attained 7-17-fold higher DA concentrations than oysters, depending on the body size and exposure time, and also detoxified DA at higher rates (1.4-1.6 d(-1)) than oysters (0.25-0.88 d(-1)) of a comparable size. Small oysters attained markedly higher weight-specific DA concentrations (maximum=78.6 μg g(-1)) than large, market-sized individuals (≤ 13 μg g(-1)), but no clear relationship was found between body size and DA concentration in mussels (maximum=460 μg g(-1)). Therefore, differential DA accumulation by the two species was, on average, approximately 3-fold more pronounced for large bivalves. An inverse relationship between DA elimination rate and body size was established for oysters but not mussels. Elimination of DA was faster in viscera than in other tissues of both bivalves; DA exchange rate from the former to the latter was higher in oysters. The contribution of viscera to the total DA burden of mussels was consistently greater than that of other tissues during both uptake (>80%) and depuration (>65%) phases, whereas it rapidly decreased from 70-80% to 30-40% in oysters, and this occurred faster in smaller individuals. Residual DA concentrations (≤ 0.25 μg g(-1)) were detected at later depuration stages (up to 14 d), mainly in viscera of oysters and non-visceral tissues of mussels, suggesting that a second, slower-detoxifying toxin compartment exists in both species. However, a simple exponential decay model was found to adequately describe DA elimination kinetics in these bivalves. The lower capacity for DA accumulation in oysters compared to mussels can thus only be explained by the former's comparatively low toxin intake rather than faster toxin elimination.
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Affiliation(s)
- Luiz L Mafra
- Institute for Marine Biosciences, National Research Council, 1411 Oxford St., Halifax, NS B3H3Z1, Canada.
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13
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Previdi M, Fennel K, Wilkin J, Haidvogel D. Interannual variability in atmospheric CO2uptake on the northeast U.S. continental shelf. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jg000881] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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14
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Falkowski PG, Katz ME, Milligan AJ, Fennel K, Cramer BS, Aubry MP, Berner RA, Novacek MJ, Zapol WM. The rise of oxygen over the past 205 million years and the evolution of large placental mammals. Science 2005; 309:2202-4. [PMID: 16195457 DOI: 10.1126/science.1116047] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
On the basis of a carbon isotopic record of both marine carbonates and organic matter from the Triassic-Jurassic boundary to the present, we modeled oxygen concentrations over the past 205 million years. Our analysis indicates that atmospheric oxygen approximately doubled over this period, with relatively rapid increases in the early Jurassic and the Eocene. We suggest that the overall increase in oxygen, mediated by the formation of passive continental margins along the Atlantic Ocean during the opening phase of the current Wilson cycle, was a critical factor in the evolution, radiation, and subsequent increase in average size of placental mammals.
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Affiliation(s)
- Paul G Falkowski
- Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, NJ 08901, USA.
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