DOCSLIB.ORG

Hypoxia in the Northern Gulf of Mexico: Does the Science Support the Plan to Reduce, Mitigate, and Control Hypoxia?

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Hypoxia in the Northern Gulf of Mexico: Does the Science Support the Plan to Reduce, Mitigate, and Control Hypoxia? Estuaries and Coasts Vol. 30, No. 5, p. 753–772 October 2007 Hypoxia in the Northern Gulf of Mexico: Does the Science Support the Plan to Reduce, Mitigate, and Control Hypoxia? N. N. RABALAIS1,*, R. E. TURNER2,B.K.SEN GUPTA2,D.F.BOESCH3,P.CHAPMAN4, and M. C. MURRELL5 1 Louisiana Universities Marine Consortium, Chauvin, Louisiana 70344 2 Louisiana State University, Baton Rouge, Louisiana 70803 3 University of Maryland Center for Environmental Science, Cambridge, Maryland 71613 4 Texas A&M University, College Station, Texas 77843 5 U.S. Environmental Protection Agency, Gulf Ecology Division, Gulf Breeze, Florida 32561 ABSTRACT: We update and reevaluate the scientific information on the distribution, history, and causes of continental shelf hypoxia that supports the 2001 Action Plan for Reducing, Mitigating, and Controlling Hypoxia in the Northern Gulf of Mexico (Mississippi River/Gulf of Mexico Watershed Nutrient Task Force 2001), incorporating data, publications, and research results produced since the 1999 integrated assessment. The metric of mid-summer hypoxic area on the Louisiana- Texas shelf is an adequate and suitable measure for continued efforts to reduce nutrients loads from the Mississippi River and hypoxia in the northern Gulf of Mexico as outlined in the Action Plan. More frequent measurements of simple metrics (e.g., area and volume) from late spring through late summer would ensure that the metric is representative of the system in any given year and useful in a public discourse of conditions and causes. The long-term data on hypoxia, sources of nutrients, associated biological parameters, and paleoindicators continue to verify and strengthen the relationship between the nitrate- nitrogen load of the Mississippi River, the extent of hypoxia, and changes in the coastal ecosystem (eutrophication and worsening hypoxia). Multiple lines of evidence, some of them representing independent data sources, are consistent with the big picture pattern of increased eutrophication as a result of long-term nutrient increases that result in excess carbon production and accumulation and, ultimately, bottom water hypoxia. The additional findings arising since 1999 strengthen the science supporting the Action Plan that focuses on reducing nutrient loads, primarily nitrogen, through multiple actions to reduce the size of the hypoxic zone in the northern Gulf of Mexico. Introduction tribal governments. The Action Plan calls for a long- The development, extent, and persistence of low term adaptive management strategy coupling man- oxygen concentrations in bottom waters of the agement actions with enhanced monitoring, mod- continental shelf of the northern Gulf of Mexico eling and research, and reassessment of accomplish- were unknown until the first systematic mapping ments and environmental indicators at five-year and monitoring of oxygen began in 1985 (Rabalais intervals. et al. 1991). At that time, shelf hypoxia (defined This paper is a component of the first reassess- here as dissolved oxygen levels at or below 2 mg l21) ment, updating the earlier reports (Rabalais et al. was recorded as localized and ephemeral (Turner 1999, 2002a,b) that considered publications and and Allen 1982). Since then, a large volume of data observations made through 1998. We review herein hasbeencollectedandnumerouspapersand new information on the spatial and temporal reports have been published that increased our (seasonal, annual, and long term) characteristics understanding of the seasonal and interannual of hypoxia on the northern Gulf of Mexico shelf distribution of hypoxia and its variability, history, developed since the Integrated Assessment and and dynamical causes. summarize the current understanding of the onset, An Integrated Assessment (CENR 2000) of the extent, and duration of the hypoxic zone. We also causes, consequences, and actions needed to reduce address the relationships between long-term trends hypoxia was completed and an Action Plan for in the extent, duration, and severity of hypoxia and Reducing, Mitigating, and Controlling Hypoxia in both increased nutrient loading and other environ- the Northern Gulf of Mexico (Mississippi River/ mental factors that may influence hypoxia, evaluat- Gulf of Mexico Watershed Nutrient Task Force ing the degree to which these relationships are 2001) was endorsed by federal agencies, states, and understood and quantified. We then answer two questions: Do new research contributions and un- * Corresponding author; tele: 985/851-2801; fax: 985/851- derstanding of the science supporting the Action 2874; e-mail: [email protected] Plan justify the prior conclusions of the Integrated ß 2007 Estuarine Research Federation 753 Estuaries and Coasts estu-30-05-02.3d 20/11/07 16:02:36 753 Cust # 4289 754 N. N. Rabalais et al. Assessment concerning increased nitrogen loads, vicinity of the river discharges as well as across the eutrophication, and worsening hypoxia and man- broader Louisiana and upper Texas continental agement scenarios to reduce nitrogen loads to the shelf. The flux of fixed carbon in the form of northern Gulf of Mexico? and Do new research senescent phytoplankton, zooplankton fecal pellets, findings give us cause to alter the concepts that or aggregates to the lower water column and seabed support management goals intended to reduce provides a large carbon source for decomposition by nitrogen loading from the Mississippi River? aerobic bacteria. Its decomposition consumes dis- solved oxygen in the water column at a higher rate Background than resupply from the upper water column in The Mississippi River forms the largest watershed a stratified water column, leading to hypoxia in on the North American continent with an annual large portions of the water column for months at average discharge of 580 km3 into the northern a time from the spring to the fall (Rabalais and Gulf of Mexico through two main distributaries: the Turner 2001; Rabalais et al. 2002a,b). birdfoot delta southeast of the city of New Orleans, Demersal fishes, crabs, and shrimp will attempt to Louisiana, and the Atchafalaya River delta 200 km move away from oxygen concentrations less than to the west (Meade 1995). The Mississippi and 2mgl21, and few marine animals survive in pro- Atchafalaya rivers are the primary sources of fresh longed exposure to oxygen concentrations below water, nitrogen, and phosphorus to the northern that level. The hypoxic area is popularly known as Gulf of Mexico, delivering 80% of the freshwater the Dead Zone. The oxygen deficient waters are not inflow, 91% of the estimated annual nitrogen load, just confined to a bottom layer, but may extend well and 88% of the phosphorus load (Dunn 1996). If up into the water column; e.g., the hypoxic water only streams between and inclusive of the Trinity mass may occupy half of the lower water column River (Galveston, Texas) and the Mississippi River (Rabalais and Turner 2001). Hypoxia, as a symptom delta are considered—those most likely to influence of eutrophication due to nutrient enrichment, is the zone of hypoxia—the Mississippi and Atchafa- a growing problem around the world (Diaz and laya rivers account for 96% of the annual freshwater Rosenberg 1995; Boesch 2002; Diaz et al. 2004). The discharge, 98.5% of the annual nitrogen load, and extent and persistence of hypoxia on the Louisiana- 98% of the total annual phosphorus load. Texas shelf makes the Gulf of Mexico Dead Zone The fresh water, sediments, and dissolved and one of the most extensive manifestations of coastal particulate materials are carried predominantly eutrophication. westward along the Louisiana-Texas inner to mid continental shelf, especially during peak spring DIMENSIONS AND VARIABILITY OF HYPOXIA discharge (Rabalais et al. 1996; Smith and Jacobs 500-km Scale 2005). Although the area of the discharge’s in- fluence is an open continental shelf, the magnitude The extent of hypoxia primarily in July averaged of flow, annual current regime, and average 75- 13,500 km2 from 1985 to 2007, with a range from d residence time for fresh water all suggest that the negligible in 1988 (a summer drought year for the shelf receiving the fresh water behaves as an Mississippi River basin) to 22,000 km2 in 2002. An unbounded estuary stratified for much of the year average of 8,200 km2 from 1985 to 1992 increased to (Dinnel and Wiseman 1986). The stratification is an average of 15,900 km2 over the next 15 yr due primarily to salinity differences, and the (Rabalais et al. unpublished data). The maximal stratification intensifies in summer with thermal extent of bottom-water hypoxia measured was warming of surface waters (Wiseman et al. 1997). 22,000 km2 in 2002 (Rabalais and Turner 2006). The primary pycnocline depth varies seasonally with The five-year average size of bottom-water hypoxia discharge and physical mixing from 3–5 m to 10– in the Gulf of Mexico for 2003–2007 was 10,500 km2 15 m in a 20-m water column (Rabalais and Turner (Fig. 1; Rabalais et al. unpublished data), which is 2001; Rabalais et al. 2002c). A secondary tempera- well above the Action Plan goal of 5,000 km2. ture-controlled pycnocline at 10 to 15 m depth in The mid-summer hypoxic water mass is distribut- a 20-m water column often caps the hypoxic water ed across the Louisiana shelf west of the Mississippi mass (Wiseman et al. 1997). River and onto the upper Texas coast (examples in Seasonal hypoxia of bottom waters in this region Fig. 2; Rabalais and Turner 2001; Rabalais et al. is the result of the strong and persistent stratifica- 2002a). Hypoxia extends from nearshore to as tion coupled with the high organic production in much as 125 km offshore and in water depths overlying surface waters that is fueled by river- extending from the shore in 4–5 m up to 60 m derived nutrients (CENR 2000). The nutrients deep. Mid-summer hypoxia usually extends along delivered from the Mississippi River Basin support a single continuous zone, but may occur in distinct the primary productivity within the immediate areas west of the Mississippi and Atchafalaya River Estuaries and Coasts estu-30-05-02.3d 20/11/07 16:02:37 754 Cust # 4289 Hypoxia Advances in the Gulf of Mexico 755 Fig.
Load more

Recommended publications
  • Biogeochemistry of Mediterranean Wetlands: a Review About the Effects of Water-Level Fluctuations on Phosphorus Cycling and Greenhouse Gas Emissions
    water Review Biogeochemistry of Mediterranean Wetlands: A Review about the Effects of Water-Level Fluctuations on Phosphorus Cycling and Greenhouse Gas Emissions Inmaculada de Vicente 1,2 1 Departamento de Ecología, Universidad de Granada, 18071 Granada, Spain; [email protected]; Tel.: +34-95-824-9768 2 Instituto del Agua, Universidad de Granada, 18071 Granada, Spain Abstract: Although Mediterranean wetlands are characterized by extreme natural water level fluctu- ations in response to irregular precipitation patterns, global climate change is expected to amplify this pattern by shortening precipitation seasons and increasing the incidence of summer droughts in this area. As a consequence, a part of the lake sediment will be exposed to air-drying in dry years when the water table becomes low. This periodic sediment exposure to dry/wet cycles will likely affect biogeochemical processes. Unexpectedly, to date, few studies are focused on assessing the effects of water level fluctuations on the biogeochemistry of these ecosystems. In this review, we investigate the potential impacts of water level fluctuations on phosphorus dynamics and on greenhouse gases emissions in Mediterranean wetlands. Major drivers of global change, and specially water level fluctuations, will lead to the degradation of water quality in Mediterranean wetlands by increasing the availability of phosphorus concentration in the water column upon rewetting of dry sediment. CO2 fluxes are likely to be enhanced during desiccation, while inundation is likely to decrease cumulative CO emissions, as well as N O emissions, although increasing CH emissions. Citation: de Vicente, I. 2 2 4 Biogeochemistry of Mediterranean However, there exists a complete gap of knowledge about the net effect of water level fluctuations Wetlands: A Review about the Effects induced by global change on greenhouse gases emission.
    [Show full text]
  • 8.4 the Significance of Ocean Deoxygenation for Continental Margin Mesopelagic Communities J
    8.4 The significance of ocean deoxygenation for continental margin mesopelagic communities J. Anthony Koslow 8.4 The significance of ocean deoxygenation for continental margin mesopelagic communities J. Anthony Koslow Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia and Scripps Institution of Oceanography, University of California, SD, La Jolla, CA 92093 USA. Email: [email protected] Summary • Global climate models predict global warming will lead to declines in midwater oxygen concentrations, with greatest impact in regions of oxygen minimum zones (OMZ) along continental margins. Time series from these regions indicate that there have been significant changes in oxygen concentration, with evidence of both decadal variability and a secular declining trend in recent decades. The areal extent and volume of hypoxic and suboxic waters have increased substantially in recent decades with significant shoaling of hypoxic boundary layers along continental margins. • The mesopelagic communities in OMZ regions are unique, with the fauna noted for their adaptations to hypoxic and suboxic environments. However, mesopelagic faunas differ considerably, such that deoxygenation and warming could lead to the increased dominance of subtropical and tropical faunas most highly adapted to OMZ conditions. • Denitrifying bacteria within the suboxic zones of the ocean’s OMZs account for about a third of the ocean’s loss of fixed nitrogen. Denitrification in the eastern tropical Pacific has varied by about a factor of 4 over the past 50 years, about half due to variation in the volume of suboxic waters in the Pacific. Continued long- term deoxygenation could lead to decreased nutrient content and hence decreased ocean productivity and decreased ocean uptake of carbon dioxide (CO2).
    [Show full text]
  • Hypoxia Infographic
    Understanding HYP XIA Hypoxia is an environmental phenomenon where the concentration of dissolved oxygen in the water column decreases to a level that can no longer 1 support living aquatic organisms. The level is often considered to be 2 mg O2 per liter of water or lower. Hypoxic and anoxic (no oxygen) waters have existed throughout geologic time, but their occurrence in shallow coastal and estuarine areas appears to be increasing as a result of human activities. 2 What causes hypoxia? In 2015, scientists determined the Gulf of Mexico dead zone to be 6,474 square miles, which is an area about the size of Connecticut and Rhode Island combined. 3 Major events leading to the formation of hypoxia in the Gulf of Mexico include: Coastal Hypoxia and Eutrophication Sunlight Watershed Areas of anthropogenically-influenced n> In the past century, Hypoxia has become a global concern with estuarine and coastal hypoxia. 550 over 550 coastal areas identified as experiencing this issue. 4 Runoff and nutrient 1 loading of the Mississippi River. Nutrient-rich water from the Mississippi River forms 1960 a surface lens. 1970 Combined, Dead Zones 1980 cover 4x the area of the 1990 Great Lakes. % 2000 Nutrient-enhanced 4 2 primary production, Only a small fraction of the 550-plus Number of dead zones has approximately Today, there is currently about 1,148,000 km2 or eutrophication. hypoxia zones exhibited any signs doubled each decade since the 1960’s. 5 of seabed covered by Oxygen Minimum Phytoplankton growth of improvement. 5 Zones (OMZs) (<0.5 ml of O /liter) 5 is fueled by nutrients.
    [Show full text]
  • Gulf of Mexico Hypoxia Monitoring Strategy
    Gulf of Mexico Hypoxia Monitoring Strategy Hypoxia Zone Areal Extent (km2) Interpolation Observations Data Analysis Workshop Steering Committee Trevor Meckley, Alan Lewitus, A White Paper by the Steering Committee of the: Dave Scheurer, Dave Hilmer NOAA National Ocean Service, National 6th Annual NOAA/NGI Hypoxia Research Centers of Coastal Ocean Science Coordination Workshop: Establishing a Steve Ashby Cooperative Hypoxic Zone Monitoring Program Northern Gulf Institute convened by the NOAA National Centers for Steve DiMarco Texas A&M University Coastal Ocean Science and Northern Gulf Institute Steve Giordano on 12-13 September 2016 at the Mississippi State NOAA National Marine Fisheries Service University Science and Technology Center at Rick Greene NASA's Stennis Space Center in Mississippi. EPA Office of Research and Development Stephan Howden University of Southern Mississippi Barb Kirkpatrick Gulf of Mexico Coastal Ocean Observing System Troy Pierce EPA Gulf of Mexico Program Nancy Rabalais Louisiana Universities Marine Consortium Rick Raynie Louisiana Coastal Protection and Restoration Authority Mike Woodside USGS National Water Quality Program Abstract The Gulf of Mexico Hypoxia Monitoring Strategy is a resource to inform the proceedings of the 6th Annual NOAA/NGI Hypoxia Research Coordination Workshop: Establishing a Cooperative Hypoxic Zone Monitoring Program. It provides a framework for a cooperative hypoxia monitoring program based on programmatic and financial requirements that are designed to meet management needs. The Monitoring Strategy includes sections on management drivers, current monitoring capabilities and gaps, and projected programmatic, data, and financial requirements based on the input of multiple partners and the responses from a survey of modelers currently applying deterministic 3D time variable models to Gulf hypoxia assessment and prediction.
    [Show full text]
  • The Potential of Mangroves in the Treatment of Shrimp Aquaculture Effluent on the Eastern Coast of Thailand
    The Potential of Mangroves in the Treatment of Shrimp Aquaculture Effluent on the Eastern Coast of Thailand 7 Nina Fancy B. Sc.(Horn), Queen's University, 1999 A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE in the Department of Geography O Nina Fancy, 2004 University of Victoria AII rights reserved. This thesis may not be reproduced in whole or in part, by photocopy or other means, without the permission of the author. Supervisor: Dr. Mark Flaherty ABSTRACT This thesis examines the potential of low-cost, low-maintenance mangroves in the treatment of nutrient-rich effluent originating from a shnmp fmon the coast of Thailand's Chanthaburi province. The objective of this thesis is to identify the environmental impact of shnmp aquaculture effluent and to determine if mangrove wetlands can be used as effective biofiltration areas to remove significant quantities of nitrate, ammonia and nitrite from shrimp wastewater. The study mangrove was found to remove an average of 44.5% of nitrate, 46.6% of ammonia and 59.0% of nitrite from shrimp effluent. The ratio of mangrove treatment area to shrimp fmrequired to adequately treat daily effluxes of wastewater from shrimp fmswas calculated to . be 1: 14. This ratio is significantly less spatially demanding than ratios calculated by .-: P 0 previous researchers and reveals the potential of mangroves to be used as large-scale wastewater treatment areas in shrimp-producing nations. TABLE OF CONTENTS .. ABSTRACT ..............................................................................................................11
    [Show full text]
  • Linking Biodiversity Above and Below the Marine Sediment–Water Interface
    Articles Linking Biodiversity Above and Below the Marine Sediment–Water Interface PAUL V. R. SNELGROVE, MELANIE C. AUSTEN, GUY BOUCHER, CARLO HEIP, PATRICIA A. HUTCHINGS, GARY M. KING, ISAO KOIKE, P. JOHN D. LAMBSHEAD, AND CRAIG R. SMITH hanges in the marine environment are evident on Ca global scale (McGowan et al. 1998), and although bio- THE ORGANISMS LIVING ON THE OCEAN diversity in the oceans is poorly described, abundances and FLOOR ARE LINKED TO THOSE LIVING IN distributions of both commercially exploited (Safina 1998) and nonexploited (Pearson and Rosenberg 1978) species have THE OCEAN ABOVE, BUT WHETHER OR changed. Not only have major changes occurred but the rate of alteration of marine ecosystems appears to be accelerating HOW THE BIODIVERSITY IN THESE TWO (e.g., Cohen and Carlton 1998). Unfortunately, the impact of these changes in biodiversity on the basic functioning of ma- REALMS IS LINKED REMAINS LARGELY rine ecosystems remains uncertain, as does the oceans’ capacity UNKNOWN to withstand multiple human disturbances (Snelgrove et al. 1997). The dynamics of many marine ecosystems, as well as of important fisheries, depend on close coupling between benthic (bottom living) and pelagic (water column) organ- The sediment–water interface (SWI) in marine ecosystems isms (Steele 1974). Our knowledge of the natural history of is one of the most clearly defined ecological boundaries on these systems remains limited, and scientific interest in map- Earth. Many organisms in the water column, such as salps ping the diversity of organisms and how they live has been and jellyfish, have flimsy and attenuated morphologies that marginalized in recent years.
    [Show full text]
  • Mixing Between Oxic and Anoxic Waters of the Black Sea As Traced by Chernobyl Cesium Isotopes
    Deep-Sea Research, Vol 38. Suppl 2. pp S72>-S745. 1991. 019~149191 53.00 + 0.00 Pnnted 10 Great Bntam © 1991Pergamon Press pic Mixing between oxic and anoxic waters of the Black Sea as traced by Chernobyl cesium isotopes KEN O. BUESSELER, * HUGH D. LIVINGSTON* and SUSAN A. CASSO* (Received 14 August 1989; in revised form 16 November 1990; accepted 28 November 1990) Abstract-The Chernobyl nuclear power station accident in 1986 released readily measureable quantities of fallout 134CS and 137Cs to Black Sea surface waters. This pulse-like input of tracers can be used to follow the physical mixing of the surface oxic waters, now labeled with the Chemobyl tracers, and the deeper anoxic waters, which were initially Chemobyl free. By 1988, there is clear evidence of Chernobyl Cs penetration below the oxic/anoxic interface at deep water stations in the western and eastern basins of the Black Sea. This rapid penetration of surface waters across the pycnocline cannot be explained by vertical mixing processes alone. Data from profiles at the mouth of the Bosporus suggest that significant ventilation of intermediate depths can occur as the outflowmg Black Sea waters are entrained with the inflowing Mediterranean waters, forming a sub-surface water mass which is recognized by its surface water characteristics, i.e. initially a relatively high oxygen content and Chernobyl Cs signal. The lateral propagation ofthis signal along isopycnals into the basin interior would provide a rapid and effective mechanism for ventilating intermediate depths of the Black Sea. This process could also account for the lateral injection of resuspended margin sediments into the basin interior.
    [Show full text]
  • Zooplankton Community Response to Seasonal Hypoxia: a Test of Three Hypotheses
    diversity Article Zooplankton Community Response to Seasonal Hypoxia: A Test of Three Hypotheses Julie E. Keister *, Amanda K. Winans and BethElLee Herrmann School of Oceanography, University of Washington, Box 357940, Seattle, WA 98195, USA; [email protected] (A.K.W.); [email protected] (B.H.) * Correspondence: [email protected] Received: 7 November 2019; Accepted: 28 December 2019; Published: 1 January 2020 Abstract: Several hypotheses of how zooplankton communities respond to coastal hypoxia have been put forward in the literature over the past few decades. We explored three of those that are focused on how zooplankton composition or biomass is affected by seasonal hypoxia using data collected over two summers in Hood Canal, a seasonally-hypoxic sub-basin of Puget Sound, Washington. We conducted hydrographic profiles and zooplankton net tows at four stations, from a region in the south that annually experiences moderate hypoxia to a region in the north where oxygen remains above hypoxic levels. The specific hypotheses tested were that low oxygen leads to: (1) increased dominance of gelatinous relative to crustacean zooplankton, (2) increased dominance of cyclopoid copepods relative to calanoid copepods, and (3) overall decreased zooplankton abundance and biomass at hypoxic sites compared to where oxygen levels are high. Additionally, we examined whether the temporal stability of community structure was decreased by hypoxia. We found evidence of a shift toward more gelatinous zooplankton and lower total zooplankton abundance and biomass at hypoxic sites, but no clear increase in the dominance of cyclopoid relative to calanoid copepods. We also found the lowest variance in community structure at the most hypoxic site, in contrast to our prediction.
    [Show full text]
  • Hypoxia the Gulf of Mexico’S Summertime Foe
    Louisiana Coastal Wetlands Planning, Protection and Restoration News September 2004 Number 26 HYPOXIA THE GULF OF MEXICO’S SUMMERTIME FOE More Nitrogen Upstream, Fewer Filters Downstream Caernarvon: A Case Study WaterMarks Interview: John Day, LSU www.lacoast.gov September 2004 Number 26 WaterMarks is published three times a Louisiana Coastal Wetlands Planning, Protection and Restoration News year by the Louisiana Coastal Wetlands Conservation and Restoration Task Force to communicate news and issues Contents of interest related to the Coastal Wetlands Planning, Protection and Restoration Act of 1990. This legislation 3 Hypoxia: funds wetlands enhancement projects The Gulf of Mexico’s Summertime Foe nationwide, designating approximately $50 million annually for work in More Nitrogen Upstream, Louisiana. The state contributes 6 Fewer Filters Downstream 15 percent of the total cost of the project. Can Wetlands Restoration 8 Revitalize Offshore Waters? Caernarvon: 10 A Case Study What Lies Ahead 12 for the Dead Zone? Please address all questions, comments and changes of address to: WaterMarks Interview: James D. Addison 14 John Day, LSU WaterMarks Editor New Orleans District US Army Corps of Engineers P.O. Box 60267 Special thanks to Doug Daigle, Mississippi River Basin Alliance; Dugan Sabins, New Orleans, LA 70160-0267 (504) 862-2201 Louisiana State Hypoxia Committee; Ken Teague, U.S. Environmental Protection Agency; and Robert Twilley, Louisiana State University, for their assistance with e-mail: this issue of WaterMarks. [email protected] For more information about Louisiana’s coastal wetlands and the efforts planned and under way to ensure their survival, check out these sites on the web: www.lacoast.gov www.btnep.org www.saveLAwetlands.org About the Cover Blue Runners, a common Gulf Subscribe species, have the ability to escape To receive WaterMarks, e-mail [email protected] from waters with low oxygen con- For current meetings, events, and other news concerning Louisiana’s coastal tent.
    [Show full text]
  • The Economics of Dead Zones: Causes, Impacts, Policy Challenges, and a Model of the Gulf of Mexico Hypoxic Zone S
    58 The Economics of Dead Zones: Causes, Impacts, Policy Challenges, and a Model of the Gulf of Mexico Hypoxic Zone S. S. Rabotyagov*, C. L. Klingy, P. W. Gassmanz, N. N. Rabalais§ ô and R. E. Turner Downloaded from Introduction The BP Deepwater Horizon oil spill in the Gulf of Mexico in 2010 increased public awareness and http://reep.oxfordjournals.org/ concern about long-term damage to ecosystems, and casual readers of the news headlines may have concluded that the spill and its aftermath represented the most significant and enduring environmental threat to the region. However, the region faces other equally challenging threats including the large seasonal hypoxic, or “dead,” zone that occurs annually off the coast of Louisiana and Texas. Even more concerning is the fact that such dead zones have been appearing worldwide at proliferating rates (Conley et al. 2011; Diaz and Rosenberg 2008). Nutrient over- enrichment is the main cause of these dead zones, and nutrient-fed hypoxia is now widely at Iowa State University on January 27, 2014 considered an important threat to the health of aquatic ecosystems (Doney 2010). The rather alarming term dead zone is surprisingly appropriate: hypoxic regions exhibit oxygen levels that are too low to support many aquatic organisms including commercially desirable species. While some dead zones are naturally occurring, their number, size, and *School of Environmental and Forest Sciences, University of Washington, Seattle, Washington, USA; e-mail: [email protected] yCenter for Agricultural and Rural Development,
    [Show full text]
  • Coupling and Decoupling of High Biomass Phytoplankton Production and Hypoxia in a Highly Dynamic Coastal System: the Changjiang (Yangtze River) Estuary
    fmars-07-00259 May 26, 2020 Time: 17:51 # 1 ORIGINAL RESEARCH published: 28 May 2020 doi: 10.3389/fmars.2020.00259 Coupling and Decoupling of High Biomass Phytoplankton Production and Hypoxia in a Highly Dynamic Coastal System: The Changjiang (Yangtze River) Estuary Feng Zhou1,2*, Fei Chai1,3*, Daji Huang1, Mark Wells3,1, Xiao Ma1, Qicheng Meng1, Huijie Xue3,4, Jiliang Xuan1, Pengbin Wang1,5, Xiaobo Ni1, Qiang Zhao6, Chenggang Liu1,5, Jilan Su5 and Hongliang Li1 1 State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China, 2 School of Oceanography, Shanghai Jiao Tong University, Shanghai, China, 3 School Edited by: of Marine Science, University of Maine, Orono, ME, United States, 4 State Key Laboratory of Tropical Oceanography, South Marta Marcos, China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China, 5 Key Laboratory of Marine University of the Balearic Islands, Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China, 6 Ningbo Marine Spain Environment Monitoring Center Station, Ministry of Natural Resources, Ningbo, China Reviewed by: Sabine Schmidt, The global increase in coastal hypoxia over the past decades has resulted from a Centre National de la Recherche Scientifique (CNRS), France considerable rise in anthropogenically-derived nutrient loading. The spatial relationship Antonio Olita, between surface phytoplankton production and subsurface hypoxic zones often can Italian National Research Council (CNR), Italy be explained by considering the oceanographic conditions associated with basin size, *Correspondence: shape, or bathymetry, but that is not the case where nutrient-enriched estuarine Feng Zhou waters merge into complex coastal circulation systems.
    [Show full text]
  • Scientific Assessment of Hypoxia in U.S. Coastal Waters
    Scientific Assessment of Hypoxia in U.S. Coastal Waters 0 Dissolved oxygen (mg/L) 6 0 Depth (m) 80 32 Salinity 34 Interagency Working Group on Harmful Algal Blooms, Hypoxia, and Human Health September 2010 This document should be cited as follows: Committee on Environment and Natural Resources. 2010. Scientific Assessment of Hypoxia in U.S. Coastal Waters. Interagency Working Group on Harmful Algal Blooms, Hypoxia, and Human Health of the Joint Subcommittee on Ocean Science and Technology. Washington, DC. Acknowledgements: Many scientists and managers from Federal and state agencies, universities, and research institutions contributed to the knowledge base upon which this assessment depends. Many thanks to all who contributed to this report, and special thanks to John Wickham and Lynn Dancy of NOAA National Centers for Coastal Ocean Science for their editing work. Cover and Sidebar Photos: Background Cover and Sidebar: MODIS satellite image courtesy of the Ocean Biology Processing Group, NASA Goddard Space Flight Center. Cover inset photos from top: 1) CTD rosette, EPA Gulf Ecology Division; 2) CTD profile taken off the Washington coast, project funded by Bonneville Power Administration and NOAA Fisheries; Joseph Fisher, OSU, was chief scientist on the FV Frosti; data were processed and provided by Cheryl Morgan, OSU); 3) Dead fish, Christopher Deacutis, Rhode Island Department of Environmental Management; 4) Shrimp boat, EPA. Council on Environmental Quality Office of Science and Technology Policy Executive Office of the President Dear Partners and Friends in our Ocean and Coastal Community, We are pleased to transmit to you this report, Scientific Assessment ofHypoxia in u.s.
    [Show full text]