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Monitoring, Modeling and Research Needs CENR TOPIC #1. Characterization of hypoxia: distribution, dynamics and causes Nancy N. Rabalais, R. Eugene Turner,

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Presentation on theme: "Monitoring, Modeling and Research Needs CENR TOPIC #1. Characterization of hypoxia: distribution, dynamics and causes Nancy N. Rabalais, R. Eugene Turner,"— Presentation transcript:

1 Monitoring, Modeling and Research Needs CENR TOPIC #1. Characterization of hypoxia: distribution, dynamics and causes Nancy N. Rabalais, R. Eugene Turner, Dubravko Justi ć, Quay Dortch and William J. Wiseman, Jr. Updates on CENR - Completed in 1999, now have data from 2000, 2001, and Continued publications - Models and sediment cores indicate that hypoxia was not severe and widespread until after the early 1970s, consistent with rise in NO 3 concentration in the river. - NO 3 concentration has leveled off in more recent years, so that discharge now has a greater influence on hypoxia than historically. - Given fluctuations in discharge dictated by climate, reduction in total N load may be more than anticipated, but lowering the concentration of NO 3 to earlier levels will bring down total load regardless of discharge patterns.

2 Area (km 2 ) (modified from Rabalais et al. 2002) Areal Extent of Hypoxic Zone Goal for 5-yr running average <5, average average 5-yr running average no data

3 Monitoring, Modeling and Research Needs CENR TOPIC #1. Characterization of hypoxia: distribution, dynamics and causes Nancy N. Rabalais, R. Eugene Turner, Dubravko Justi ć, Quay Dortch and William J. Wiseman, Jr. Updates on CENR - Completed in 1999, now have data from 2000, 2001, and Continued publications - Models and sediment cores indicate that hypoxia was not severe and widespread until after the early 1970s, consistent with rise in NO 3 concentration in the river. - NO 3 concentration has leveled off in more recent years, so that discharge now has a greater influence on hypoxia than historically. - Given fluctuations in discharge dictated by climate, reduction in total N load may be more than anticipated, but lowering the concentration of NO 3 to earlier levels will bring down total load regardless of discharge patterns.

4 Selected Publications Rabalais, N. N. and R. E. Turner (eds.) Coastal Hypoxia: Consequences for Living Resources and Ecosystems. Coastal and Estuarine Studies 58, American Geophysical Union, Washington, D.C. Turner, R. E., N. N. Rabalais, D. Justić and Q. Dortch. In press. Global patterns of dissolved N, P and Si in large rivers. Biogeochemistry. Childs, C. R., N. N. Rabalais, R. E. Turner and L. M. Proctor Sediment denitrification in the Gulf of Mexico zone of hypoxia. Marine Ecology Progress Series 240: Rabalais, N. N Nitrogen in aquatic ecosystems. Ambio 31(2): Rabalais, N. N., R. E. Turner, Q. Dortch, D. Justic, V. J. Bierman, Jr. and W. J. Wiseman, Jr. in press Review. Nutrient-enhanced productivity in the northern Gulf of Mexico: past, present and future. Hydrobiologia. Rabalais, N. N., R. E. Turner and D. Scavia Beyond science into policy: Gulf of Mexico hypoxia and the Mississippi River. BioScience 52: Special Issue ESTUARIES, 2002, 4B, Nutrient Over-Enrichment in Coastal Waters

5 Monitoring, Modeling and Research Needs CENR TOPIC #1. Characterization of hypoxia: distribution, dynamics and causes Nancy N. Rabalais, R. Eugene Turner, Dubravko Justi ć, Quay Dortch and William J. Wiseman, Jr. Updates on CENR - Completed in 1999, now have data from 2000, 2001, and Continued publications - Models and sediment cores indicate that hypoxia was not severe and widespread until after the early 1970s, consistent with rise in NO 3 concentration in the river. - NO 3 concentration has leveled off in more recent years, so that discharge now has a greater influence on hypoxia than historically. - Given fluctuations in discharge dictated by climate, reduction in total N load may be more than anticipated, but lowering the concentration of NO 3 to earlier levels will bring down total load regardless of discharge patterns.

6 New Modeling Efforts Models to predict size - Scavia et al. – riverine dissolved oxygen model to simulate present hypoxic area size (length and area), also to hindcast - Turner – model based on offshore TKN values from to predict hypoxic area - Rabalais et al. – simple regressions, predict hypoxic area Oxygen Dynamics - Justic et al. – oxygen budget with isotopes, surface and bottom  5-m intervals Models to predict temporal sequence - Justic et al. – model to simulate present oxygen temporal dynamics related to Miss R nitrate flux, hindcast similar dynamics to 1950s - Justic et al. – same model with various climate scenarios

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8 New Modeling Efforts Models to predict size - Scavia – riverine dissolved oxygen model to simulate present hypoxic area size (length and area), also to hindcast - Turner – model based on offshore TKN values from to predict hypoxic area - Rabalais et al. – simple regressions, predict hypoxic area Oxygen Dynamics - Justic et al. – oxygen budget with isotopes, surface and bottom  5-m intervals Models to predict temporal sequence - Justic et al. – model to simulate present oxygen temporal dynamics related to Miss R nitrate flux, hindcast similar dynamics to 1950s - Justic et al. – same model with various climate scenarios

9 Justic et al. (2002)

10 Hypoxia Studies - Mid-summer shelfwide, monthly trans C, bimonthly trans F, mooring - CTD/O, biological & chemical data, surface flow-through mapping, ADCP - Physics of currents and vertical mixing in relation to winds -Mooring with top, middle, surface, now ADCP, nutrient & light meters, to become telemetered, along with meteorology, waves - Interesting initial results from ADCP - Correlating seasonal productivity with hypoxia, remote sensing - Uniform size calculations, ours and others - Developing volume estimates - Web site development,

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12 Hypoxia Studies - Mid-summer shelfwide, monthly trans C, bimonthly trans F, mooring -CTD/O, biological & chemical data, surface flow-through mapping, ADCP -Mooring with top, middle, surface oxygen/C/T, other C/T, now ADCP, nutrient & light meters, to become telemetered, along with meteorology, waves - Physics of currents and vertical mixing in relation to winds - Interesting initial results from ADCP - Correlating seasonal productivity with hypoxia, remote sensing - Uniform size calculations, ours and others - Developing volume estimates - Web site development,

13 Related Studies - Isotope work and oxygen budget model - N 2 O production in hypoxic waters - Completion of sediment denitrification studies summer 2000 and 2001 Other COP-funded Studies - Analysis of SEAMAP data for oxygen distribution and fish community dynamics with a focus on croaker - Extant fish communities with hypoxia - Historical analysis of fisheries data - Fish larvae and Mississippi River plume - Retrospective analysis and modeling of food web dynamics in the Mississippi River Plume

14 Funded and Potential Collaborative Studies (need to take advantage of and integrate with any relevant work underway, potentially to be funded, or planned) For Example: - Improving HPLC and phytoplankton biomass conversions - MultiStressors, Barataria Basin - CoOP, river buoyant plume dynamics Importance of Integration of COP-funded projects

15 Priorities on monitoring and modeling and research to reduce uncertainties ID’d in CENR process (relevant to both watershed & Gulf) - Coordinated monitoring efforts must be suitable to detect trends, long- term and short-term, to evaluate the effectiveness of management actions, to enable effective adaptation of strategies. - Monitor those physical, chemical and biological characteristics and processes relevant in the cause-and-effect relationships between nutrient inputs and resulting environmental quality. - Differentiate among trends caused by changes in climate, streamflow, nutrient and landscape measures, and other concurrent factors. - Integrate monitoring and research results into holistic models that simulate our understanding of how the overall system functions and how management practices can best be implemented. - Monitoring results should be designed to both provide input variables to the model(s) and verify model outputs.

16 IA Immediate Research Priorities - Past, current, and potential impacts of hypoxia on both commercially and economically important species and ecosystems - retrospective analysis based on sediment cores and existing data bases - better understanding of the effects of other factors that affect the ecological health and fisheries of the N Gulf of Mexico - Dynamics and timing of transport of nitrogen and other nutrients from the landscape into streams and coastal waters - Geographic location and design criteria for wetlands and other strategies (e.g., riparian zones) for effective nitrate reduction - Influence of on-farm practices on transport of nitrogen and other nutrients into streams - Better methods to intercept agriculture nutrients between the fields and ground water and adjacent streams - Effectiveness of current and potential policies and actions to reduce nutrient loss on a basin scale. Top#1&2 Top#1

17 IA Longer-Term Research Priorities - Nutrient cycling and carbon dynamics across the MARB and relationship of site-specific actions to Basin-scale effects - Characterize mineralization and immobilization processes to better understand the amount and forms of nitrogen in the soil reservoir and to develop strategies to minimize leaching of nitrate into streams - Quantify denitrification and nutrient retention rates in streams and in Gulf sediments and compare to that achieved in riparian zones and wetlands - Relationships among nutrient fluxes, nutrient ratios, and nutrient cycling on the continental shelf of the Gulf of Mexico - Amount and composition of atmospherically deposited nitrogen in the Gulf - Relationship between large-scale climate patterns and impacts on river flows, nutrient flux, and flow dynamics on the continental shelf - Role of flood prevention and control methods in retaining nitrogen in MARB - Better understand nutrient cycling in the deltaic plain to guide potential changes in land management activities -Aggregated analysis of direct (drinking water protection) and indirect (recreational improvements) improvements in water quality in MARB. N- Potential economic effects of hypoxia on ecology of the Gulf, w/ impacts to biodiversity and nonmarket-valued ecosystem goods and services. - Better estimates of the economic benefits to agricultural producers from reduced fertilizer use and to society from nitrogen management or reduction. Top#1

18 Outstanding Issues and Information Gaps (NNR from CENR #!) - Specifics to distribution, dynamics and causes of hypoxia. - Improved temporal coverage of the spatial extent of hypoxia. - improved geographic coverage and finer resolution of sediment markers for surface productivity and bottom water hypoxia. - Empirical relationships with seasonal cycle of hypoxia, summer hypoxia, and nutrient flux and nutrient ratios. - Improved understanding of biological and oceanographic processes involved in the development and maintenance of hypoxia, and its distribution, and the interaction of biology and physics.

19 Outstanding Issues and Information Gaps (NNR) (cont’d) - Predictive capability for estimating temporally hypoxia extent, severity and duration, related to seasonal dynamics of nutrient flux and freshwater discharge. - Temporal changes in the phytoplankton community in relation to nutrient flux and nutrient ratios, and the flux of organic material to the seabed. - Fate of carbon, food web (pelagic and benthic), remineralization (water column and sediments), resuspension and transport, and burial. - Nutrient, carbon, and oxygen dynamics at the sediment-water interface. - Nature and timing of response of seasonally hypoxic ecosystem to reduction in nutrient flux. - Better relative contribution of N sources to the area affected by hypoxia.

20 - Influence of hypoxia on distribution of pelagic and benthic organisms (multiple trophic levels and life stages). - Whole system, trophic dynamics; dynamic, coupled biological-physical model. -Continue modeling with smaller parts that are more manageable, and build through time as research and monitoring provides the input values. - Be careful not to force this system into existing models that may not be appropriate, or need to be modified. - Area or volume related models will only give annual, long-term conditions related to discharge and nutrient flux (integrated over some time interval) - Finer temporal models will be useful in identifying the system’s response to changed temporal patterns of nutrient flux resulting from nutrient management. - Suitable economic indicators for coastal resources and ecosystem services. Outstanding Issues and Information Gaps (NNR) (cont’d) Venture somewhat outside of my CENR #1 hypoxia box:

21 From IA: MONITORING NEEDS A comprehensive monitoring program requires both measurement of environmental response in the MARB and the Gulf of Mexico and tracking indicators of programmatic progress toward mitigating excessive nutrients. Environmental Responses in the Gulf Essential components in the Gulf of Mexico include: -Document the temporal and spatial extent of shelf hypoxia, and collect basic hydrographic, chemical, and biological data related to the development and maintenance of hypoxia over seasonal cycles. -mid-summer shelf ‑ wide hypoxia surveys, -monthly transects off Terrebonne Bay [bimonthly off Atchafalaya] - instrumented arrays at stations in the core of the hypoxic zone -optimal combination of spatial and temporal scales of measurement - consistent with the existing long-term data. -multiple vertical and horizontal instrument arrays oriented cross ‑ shelf and along ‑ shelf will better define processes that control the temporal and spatial development of hypoxia.

22 From IA: MONITORING NEEDS (cont’d) - Improve the collection of ecological, production, and economic information related to fishery and nonfishery species. - Facilitate synthesis and interpretation of these data through an integrated database.


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