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The Dead Zones: -Starved Coastal Waters Author(s): Stephanie Joyce Source: Environmental Health Perspectives, Vol. 108, No. 3 (Mar., 2000), pp. A120-A125 Published by: The National Institute of Environmental Health Sciences Stable URL: http://www.jstor.org/stable/3454426 Accessed: 31-01-2017 20:51 UTC

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This content downloaded from 208.96.144.234 on Tue, 31 Jan 2017 20:51:24 UTC All use subject to http://about.jstor.org/terms Focus ? The Dead Zones

the Universities Marine term commitment both to reducing nutrient ities including land transformation, ground? Consortium. inputs and to conducting basic research to water drainage, urban runoff, Scientists attribute the improve understanding of coastal ecosystems sewage treatment, or atmospheric emissions hypoxic zone largely to nutrient runoff and (par?how human activities affect them. through fossil fuel burning and volatilization ticularly ) from agriculture in the of agricultural waste. "It's as if we've taken enormous Mississippi basin, which releasesThe Causes and Consequences of these already-hypoxia-prone systems and 1.6 million metric tons of nitrogen annually, Hypoxia pushed them over the edge," says Danielle according to the Integrated Assessment Hypoxia ofand even anoxia?a total loss of oxy? Luttenberg, coordinator of the Harmful Algal Hypoxia in the Northern Gulf of Mexico, gen?occur a naturally in many of the world's Bloom Monitoring and Assessment Program draft summary of six reports on various basins and seas and also along some at the U.S. National Oceanic and aspects of hypoxia in the Gulf of Mexicocoasdines. Periodic anoxia occurs in one-third Atmospheric Administration (NOAA). commissioned by the White House of U.S. and hypoxia occurs in half, Hypoxia is part of a series of ecosystem Committee on Environment and Natural particularly in the Gulf of Mexico and the responses to declines in water quality. It gen? Resources (CENR). During the warm mid-Adantic. Troughs in the erally affects enclosed water bodies such as months, these nutrients fuel , and the rippling floor of the Long Island lakes, bays, estuaries, and seas, where local which causes excessive algal blooms that can Sound are also prone to hypoxia. Periodic and conditions including bottom topography, degrade aquatic habitats by reducing light lev? seasonal cycles of enhanced algal growth occur wind and wave patterns, and inflow from els, destroying habitats (including fragile sys? naturally when warm temperatures and ade- large rivers promote stratification, the separa- tems such as coral reefs), and harming marine quate nutrients are present, and can con- tion of oxygen-rich upper layers of water from life by producing toxins, some of which also tribute to hypoxia. Overall, however, the the lower, less-oxygenated layers. Hypoxia harm humans. form the base of the widespread global increase of eutrophication changes the energy flow of marine systems, , but when they bloom in excess, and hypoxia points to human causes. altering the dynamics of the food chain, says their decay in eutrophic waters can promote Most programs seeking to reduce coastal Robert J. Diaz, a professor of marine science hypoxia. eutrophication and hypoxia target sources of at the College of William and Mary in Although the Gulf of Mexico hypoxic nitrogen because nitrogen concentrations con? Williamsburg, Virginia, who specializes in the zone is the largest anthropogenic in trol growth in saltwater. effects of hypoxia. "In nonhypoxic conditions, the Western Hemisphere, it is only one of Nitrogen is essential to most living organisms, sun and nutrients support the growth of phy? many. Reports of hypoxic events have been and in a fixed form (combined with other ele? toplankton, which can be considered the base increasing since the mid-1960s. Worldwide, ments) it controls the productivity and species of the food chain for many and inverte- dead zones exist in areas such as Japan's Seto composition?the type and proportion of brate species," Diaz says. "The portion of phy? Island Sea and its harbors, the northern algae in a given area?of many ecosystems. toplankton . . . that settles to the bottom , the (with over 38,000 But human additions of fixed nitrogen have through the [a vertical cross- mi2 of hypoxic water, about 33% of the sea), vasdy altered the . In an article section of water from surface to bottom] is the the (90% hypoxic), and many oth- in the 25 July 1997 issue of Science, Peter energy for a basic food chain of worms to ers. Marine ecosystems are complex and Vitousek and colleagues stated that anthro? shrimp, crabs, and bottom-feeding fish. incompletely understood, and human activi? pogenic changes to the nitrogen cycle have When too much [phytoplankton] gets to the ties cannot always be named as direct causes doubled relative to similar changes to the car? bottom, the invertebrates can't handle the of hypoxia. However, problems in dead zones bon cycle. Anthropogenic inputs add as much excess food, which leads to bacterial blooms such as in the Gulf of Mexico parallel a global as 190 metric tons of fixed nitrogen per year and to oxygen depletion if bottom waters are decline in water quality associated with to terrestrial systems, Vitousek says. While stratified." When excess nutrients reach strati? increasing human populations and coastal agriculture is the main source for much of the fied water, a progression of responses results, development, and scientists generally concur nitrogen, water quality problems in other starting with eutrophication. The primary that eutrophication and hypoxia should be areas may stem from a variety of human activ- nutrients of concern are nitrogen and phos- taken very seriously. A June 1999 report from the National Academy of Sciences' Council for Agricultural Science and Technology, Gulf of Mexico Hypoxia: Land and Sea Interactions, states that hypoxic zones "are now one of the most widespread, accelerating, human-induced deleterious impacts in the world's marine environments." In 1998, following a request by the U.S. Environmental Protection Agency (EPA), the CENR commissioned its series of six reports summarizing the scientific knowledge, envi? ronmental and ecological consequences, and possible remedies for hypoxia in the Gulf of Mexico. The six reports, issued in spring 1999, show that in the Mississippi, as in other U.S. and international coastal regions, human activities have caused ecosystem changes that may affect human, economic, and environ? mental health in the short and long term. Reversing these changes will require a long- Source: Downing JA, et al. Gulf of Mexico hypoxia: land and sea interactions. Task force report no. 134. Ames, IA:Council for Agricultural Science and Technology, 1999;6.

Environmental Health Perspectives ? Volume 108, Number 3, March 2000 A 121

This content downloaded from 208.96.144.234 on Tue, 31 Jan 2017 20:51:24 UTC All use subject to http://about.jstor.org/terms Focus ? The Dead Zones

the Louisiana Universities Marine term commitment both to reducing nutrient ities including land transformation, ground? Consortium. inputs and to conducting basic research to water drainage, urban stormwater runoff, Scientists attribute the Gulf of Mexico improve understanding of coastal ecosystems sewage treatment, or atmospheric emissions hypoxic zone largely to nutrient runoff and how (par? human activities affect them. through fossil fuel burning and volatilization ticularly nitrogen) from agriculture in the of agricultural waste. "It's as if we've taken enormous Mississippi basin, which Thereleases Causes and Consequences of these already-hypoxia-prone systems and 1.6 million metric tons of nitrogen annually, Hypoxia pushed them over the edge," says Danielle according to the Integrated Assessment Hypoxia and of even anoxia?a total loss of oxy? Luttenberg, coordinator of the Harmful Algal Hypoxia in the Northern Gulf of Mexico, gen?occur anaturally in many of the world's Bloom Monitoring and Assessment Program draft summary of six reports on oceanvarious basins and seas and also along some at the U.S. National Oceanic and aspects of hypoxia in the Gulf of coastlines.Mexico Periodic anoxia occurs in one-third Atmospheric Administration (NOAA). commissioned by the White ofHouse U.S. estuaries and hypoxia occurs in half, Hypoxia is part of a series of ecosystem Committee on Environment and Natural particularly in the Gulf of Mexico and the responses to declines in water quality. It gen? Resources (CENR). During the warm mid-Adantic. Troughs in the Chesapeake Bay erally affects enclosed water bodies such as months, these nutrients fuel eutrophication, and the rippling floor of the Long Island lakes, bays, estuaries, and seas, where local which causes excessive algal blooms that can Sound are also prone to hypoxia. Periodic and conditions including bottom topography, degrade aquatic habitats by reducing light lev? seasonal cycles of enhanced algal growth occur wind and wave patterns, and inflow from els, destroying habitats (including fragile sys? naturally when warm temperatures and ade- large rivers promote stratification, the separa- tems such as coral reefs), and harming marine quate nutrients are present, and can con- tion of oxygen-rich upper layers of water from life by producing toxins, some of which also tribute to hypoxia. Overall, however, the the lower, less-oxygenated layers. Hypoxia harm humans. Algae form the base of the widespread global increase of eutrophication changes the energy flow of marine systems, food chain, but when they bloom in excess, and hypoxia points to human causes. altering the dynamics of the food chain, says their decay in eutrophic waters can promote Most programs seeking to reduce coastal Robert J. Diaz, a professor of marine science hypoxia. eutrophication and hypoxia target sources of at the College of William and Mary in Although the Gulf of Mexico hypoxic nitrogen because nitrogen concentrations con? Williamsburg, Virginia, who specializes in the zone is the largest anthropogenic dead zone in trol phytoplankton growth in saltwater. effects of hypoxia. "In nonhypoxic conditions, the Western Hemisphere, it is only one of Nitrogen is essential to most living organisms, sun and nutrients support the growth of phy? many. Reports of hypoxic events have been and in a fixed form (combined with other ele? toplankton, which can be considered the base increasing since the mid-1960s. Worldwide, ments) it controls the productivity and species of the food chain for many fish and inverte- dead zones exist in areas such as Japan's Seto composition?the type and proportion of brate species," Diaz says. "The portion of phy? Island Sea and its harbors, the northern algae in a given area?of many ecosystems. toplankton . . . that settles to the bottom Adriatic Sea, the Baltic Sea (with over 38,000 But human additions of fixed nitrogen have through the water column [a vertical cross- mi2 of hypoxic water, about 33% of the sea), vastly altered the nitrogen cycle. In an article section of water from surface to bottom] is the the Black Sea (90% hypoxic), and many oth- in the 25 July 1997 issue of Science, Peter energy for a basic food chain of worms to ers. Marine ecosystems are complex and Vitousek and colleagues stated that anthro? shrimp, crabs, and bottom-feeding fish. incompletely understood, and human activi? pogenic changes to the nitrogen cycle have When too much [phytoplankton] gets to the ties cannot always be named as direct causes doubled relative to similar changes to the car? bottom, the invertebrates can't handle the of hypoxia. However, problems in dead zones bon cycle. Anthropogenic inputs add as much excess food, which leads to bacterial blooms such as in the Gulf of Mexico parallel a global as 190 metric tons of fixed nitrogen per year and to oxygen depletion if bottom waters are decline in water quality associated with to terrestrial systems, Vitousek says. While stratified." When excess nutrients reach strati? increasing human populations and coastal agriculture is the main source for much of the fied water, a progression of responses results, development, and scientists generally concur nitrogen, water quality problems in other starting with eutrophication. The primary that eutrophication and hypoxia should be areas may stem from a variety of human activ- nutrients of concern are nitrogen and phos- taken very seriously. A June 1999 report from the National Academy of Sciences' Council for Agricultural Science and Technology, Gulf of Mexico Hypoxia: Land and Sea Interactions, states that hypoxic zones "are now one of the most widespread, accelerating, human-induced deleterious impacts in the world's marine environments." In 1998, following a request by the U.S. Environmental Protection Agency (EPA), the CENR commissioned its series of six reports summarizing the scientific knowledge, envi? ronmental and ecological consequences, and possible remedies for hypoxia in the Gulf of Mexico. The six reports, issued in spring 1999, show that in the Mississippi, as in other U.S. and international coastal regions, human activities have caused ecosystem changes that may affect human, economic, and environ? mental health in the short and long term. Reversing these changes will require a long- Source: Downing JA, et al. Gulf of Mexico hypoxia: land and sea interactions. Task force report no. 134. Ames, IA:Council for Agricultural Science and Technology, 1999;6.

Environmental Health Perspectives ? Volume 108, Number 3, March 2000 A 121

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symptom of secondary eutrophication. salmon along the western U.S. and CanadianEcology Institute in Baton Rouge and Nancy Histone trends from 1970 to 1995 showcoast. thatAccording to NOAA's Integrated N. Rabalais Report of the Louisiana Universities worsening conditions outnumber improve-on Harmful Algal Blooms, HAB outbreaks Marine Consortium also suggests that changes ments, the report says. have increased globally in scope, duration,in the relative concentrations of nitrogen, sili? and economic costs?though increased ca, and , especially a decrease in Other Causes: Algal Blooms and reporting may be due to better monitoring, silica relative to nitrogen, may be causing a Climate the report says. change in algal community composition. "As Anthropogenic nutrient loading isMany also species that cause HABs (suchthe ratio as changes, there are shifts in the types believed to be contributing to the the global"red tides" caused by the toxin-producing of phytoplankton produced," Rabalais says. In increase in the frequency, size, and dinoflagellatesduration Alexandrium aspp. June and1996 paper in the journal Estuaries, of harmful algal blooms, known asGymnodinium HABs, breve, both of which Rabalais periodi- and colleagues documented the which can alter the function of coastal cally ecosys? trigger shellfishery closures in appearance the U.S. of phytoplankton species not tems or potentially threaten human northeast health. and southeast) are not associatedfound in pre-1950 . These include Such blooms have caused large-scale withdeaths polluted in water but are current-borne. Dinophysis caudata, a associated both wild and farmed stocks of economically They exist naturally in certain marine with diarrheicareas, shellfish poisoning, and Pseudo- important seafood species. In 1986 and they1989, have been around for a long nitzschia, time. a species usually found in the waters the golden-brown algae Heterosigma "Theakashiwo was noted by the Spaniardsoff the U.S. west . Some varieties of killed a total of $10.5 million worth ofwhen farmed they were exploring Florida," Pseudo-nitzschia says emit a toxin called domoic Luttenberg. "But some species do respond acid that accumulatesto in the tissues of fish and nutrient levels. Harmful shellfish [blue- and can cause permanent amnesia in The flow to the sea. Three major nutrients, , which bloom in fresh people or low- and animals who eat contaminated nitrogen (N), phosphorus (P), and silicon (Si), seafood. are released from agricultural landscapes saline water] by are pretty clearly related to nutri? wind erosion, volatilization, loss from ents. soil, Andand research from all over the worldStates affected by HABs routinely moni? sewage and waste treatment. Rain andindicates dust, a relationship between macroalgae tor for outbreaks of algal blooms, following as well as runoff and subsurface flow, and deposit nutrients. Some HABs may respond guidelines toset by the U.S. Food and Drug these nutrients into waterways and onto land. changes in nutrient levels, or they Administration. may Litde is known about the role Nutrients may also be trapped in and lakes. respond to nutrient ratios." of toxic algae in their habitats or about their Source: Downing JA, et al. Gulf of Mexico hypoxia: land and sea interactions. effects on animals and humans, but state and Task force report no. 134. Ames. IA:Council for Agricultural ScienceResearch and by teams led by R. Eugene Technology. 1999;24. Turner of Louisiana State University's federal Coastal agencies are supporting studies aimed

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Environmental Health Perspectives ? Volume 108, Number 3, March 2000 A123

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at broadening understanding of the habitat, biology, and ecology of HABs. The Centers for Disease Control and Prevention has begun studies of the respiratory health effects associ? ated with aerosolized red tide toxins, and pro? tocols are being developed to study liver and kidney damage in humans exposed to cyanobacterial toxins in blue-green tides. Scientists are also trying to incorporate data on and variability into questions about water quality. "One of the key questions in water quality is how to tease apart human effects and the effects of hurri- canes," says Hans Paerl, Kenan professor of marine and environ? mental sciences at the University of North Source: Downing JA, et al. Gulf of Mexico hypoxia: land and sea interactions. Carolina at Chapel Task force report no. 134. Ames, IA:Council for Agricultural Science and Hill's Institute of Technology, 1999;7, 19. Marine Sciences in Morehead City. Excessive algal growth mal levels.and Chlorophyll levels doubled, and a two- to threefold since the 1950s. Since 1980, blooms responding to increased nutrient week load? later, hypoxia appeared throughout the the Mississippi and Atchafalaya Rivers have ing is a serious water quality problem estuaries in the and in parts of the sound. Then annually discharged 1.6 million metric tons of Neuse River , which opens into came North Irene. "Hurricane Irene remixed nitrogen (mosdy ), 100,000 metric tons Carolina's Pamlico Sound, a major Pamlico Sound, but the nutrients are stillof phosphorus, and 200,000 metric tons of nursery for the mid-Atlantic. "The there Neuse because the Outer Banks prevents theirsilica into the basin, according to the estuary is affected by nutrient loading expulsion from to the coastal ocean," says Paerl. Integrated Assessment of Hypoxia in the agricultural, urban, and industrial sources, "We think there's a high potential for algal Northern Gulfof Mexico. The report adds that and conversion of upstream and coastal blooms wet? if we have a hot, calm spring andabout 56% of the nitrate enters the lands to housing and other development. summer in 2000. We should be prepared Mississippifor above the Ohio river, in the six Nitrogen loading to the estuary has increased unusual biological events that may at least states where agricultural production is highest, by at least 30% over the past 20 years," temporarily Paerl impair water quality and fisheries and that eutrophication has impaired water says. habitat." quality throughout the basin. The combination of eutrophication and The waters of the Mississippi and vertical salinity stratification (in which low- Case Study: Hypoxia in the Gulf of Atchafalaya Rivers provide 60% of the fresh? Mexico density freshwater overlays higher-density salt- water input to the Gulf of Mexico. When water but does not mix with it, turning the The Gulf of Mexico hypoxia problem demon- they reach the gulf, the waters form a broad, lower layer into a so-called salt wedge) makes strates the often conflicting interaction nutrient-rich, stratified plume that supports the Neuse estuary prone to hypoxia. Also, the between human productivity and ecosystem algal blooms along the continental shelf, islands of the Outer Banks partially enclose health. In the course of its nearly 4,000-mile extending from Louisiana to eastern . the greater Pamlico Sound, greatly reducing journey to the Gulf of Mexico, the Mississippi Beginning in late spring, hypoxia appears water and nutrient exchange with the coastal River enfolds the flow of many large rivers? across the shelf, generally at depths of 5-30 ocean. As a result, nutrient inputs entering the the Ohio, the Arkansas, the Missouri, the meters. Unless winds or tropical storms mix sound can remain there for at least a year, Illinois, and the Tennessee?along with their the water, hypoxia and anoxia may persist for Paerl explains. Blooms of , cryp- innumerable small and large tributaries. The weeks to months from May to September. tomonads (a type of biflagellate algae), and Mississippi basin is hugely important eco- During hypoxic periods, the abundance and blue-green algae commonly appear in the nomically; it drains 31 states and 40% of the of fish and shrimp in the hypoxic upper estuary. Paerl and his colleagues will contiguous United States. The basin repre? zone diminishes, causing commercial shrimp- monitor the Neuse/Pamlico system closely to sents 55% of American agricultural lands and ing to shift to nonhypoxic zones. However, observe effects on algal growth and fish fol? 33% of U.S. farm-related jobs, and produces according to the second of the six CENR lowing the three hurricanes?Dennis, Floyd, over $98 billion annually in agriculture, reports, Topic 2: Ecological and Economic and Irene?that struck the North Carolina according to Gulf of Mexico Hypoxia. Consequences of Hypoxia, statistical reductions coast between September and October 1999. However, productivity in the Mississippi in overall catches were not measured (though "We've had a 200-500-year flood event and basin has been ecologically costly. The the report states that reductions may have have never seen anything approaching this Mississippi's flow has been extensively altered occurred). magnitude," Paerl says. since the mid-1800s through elimination of Like many U.S. coastal ecosystems, the A week after Hurricane Floyd struck, wetlands (which can help control nutrient Gulf of Mexico was not monitored until nutrient-laden freshwater from the Neuse, runoff), construction of navigation and flood water quality degradation was advanced. The Tar, and Pamlico Rivers sent coffee-colored control levees, and annexation of the first documentation of hypoxia in the Gulf of plumes deep into the blue-gray water of the Atchafalaya River for flood control. Riverine Mexico occurred during the 1970s in connec- sound, and salinity dipped to 30-50% of nor- nutrient loads from agriculture have increased tion with environmental assessments of oil

A 124 Volume 108, Number 3, March 2000 ? Environmental Health Perspectives

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production and studies of transportation to address waterin quality problems affecting and in Tampa Bay, reductions in nutrient the gulf. Routine data gathering on thethe Baltic extent Sea and the Danube . In loads have begun to result in improved water and effects of hypoxia in the gulf the began Seto Island in Sea, efforts to halve nutrient clarity, reduced cyanobacterial bloom, increas? 1985, led by Turner and Rabalais. runoffSampling appear to be slowly reducing eutrophi? es in sea grass growth, and rising catches of during annual five-day cruises documented cation levels. valuable fish, such as speckled trout, that and mapped the presence of hypoxia Governments in the and citizens groups have depend on the sea grasses. In North Carolina, gulf, though Rabalais cautions that launched the maps a number of extensive programs to says Paerl, well-defined nutrient cutbacks, made during the surveillance cruises reduce should eutrophication be and hypoxia caused by including a legislatively mandated 30% reduc? seen as incomplete snapshots. "What various these human activities in a number of U.S. tion in nitrogen inputs into the Neuse River maps show is only a five-day picture water of bodies. the A multi-state, multi-stakeholder basin, have been formulated to reduce hypox? whole process," she says. campaign begun in 1987 on behalf of the ic effects. Research by Turner, Rabalais, and Chesapeake others Bay sought to reduce overall There appears to be strong federal support has shown correlations between increased nitrogen fer? and phosphorus loading from point for reversing coastal hypoxia. The issue is tilizer use and productivity and oxygen sources deple? such as wastewater treatment and being addressed through a number of laws tion in the Gulf of Mexico. In the absencenonpoint sourcesof such as transportation and including the Clean Water Act, the Clean Air long-term data on riverine nutrient agricultureand oxy? by 40% by this year (this goal has Act, and the Harmful and gen concentrations, research teams not analyzed yet been met, however). In the highly Hypoxia Research Control Act of 1998. As cores extracted from the bed urbanized in the Long Island Sound, where hypoxia, part of the Clean Water Initiative, President coastal shelf, which represented organic declining depo? water quality, and algal blooms Bill Clinton set aside $5 billion, including sition from 1904 through recent threaten years. marine resources potentially worth $322 million for the Gulf of Mexico, for pro? Analysis of organic matter buried in $4.9 the billion sedi? (in terms of jobs, commercial jects to clean up America's waterways. To ments showed that eutrophication fishing andand processing, and recreational boat- address the basin management concept in the increased organic production began ing, to fishing,grow and swimming), studies showed Mississippi basin, the EPA has divided the in the 1940s, in parallel with increasing that theuse major of nitrogen contributor was par- watershed into six sub-basins and has begun agricultural . In a series oftially papers, treated sewage. With the cooperation of developing strategies for addressing water Turner, Rabalais, and other researchers the EPA, state and local governments and quality in each. The EPA is also developing showed a decline in benthic foraminifera major wastewater and treatment companies in nutrient assessment criteria based on water ostracods (shelled organisms that Connecticut require and New York (the states bor- quality indicators (such as chlorophyll, turbid- highly oxygenated waters), also coincidentdering tiie sound) are upgrading their plants ity, and total nitrogen) for three water body with increased use, indicating to help meet a goal of 58% reduction in point types (lakes/reservoirs, streams/rivers, and increasing oxygen stress in the gulf sourcebeginning nutrient deposition. estuaries/coastlines), to be completed by in the 1950s and accelerating in the 1980s. Many researchers look to the Chesapeake 2003. NOAA, the EPA, and other federal Bay's basin management program as a model agencies are supporting and collaborating on The Way to Cleaner Water for addressing water quality. Though there research to expand understanding of hypoxia Scientists contributing to the six has beenCENR no significant change in overall water and the causes and controls of eutrophication reports concur that water quality and quality hypoxia in tiie bay?algal blooms and hypoxia in terms of climatic, physical, and chemical could worsen even if nutrient inputs still dooccur, not and strategies to address inputs factors and human interactions with the envi? increase because of other factors fromincluding agriculture, power plants, and auto ronment. weather patterns, temperature, and precipita?emissions have not reduced nutrient loads as In the conclusion of the first of the six tion in the gulf and the .expected?conditions The have improved in sever? CENR reports, Topic 1: Characterization of remediation options oudined in the Integrated al contributing rivers where nutrient loading Hypoxia, Rabalais and her coauthors urge Report on Harmful Algal Blooms are was to diminished,reduce and there has been a modest multi-level, multi-institutional support as a nitrogen inputs to streams and rivers recovery in ofthe sea grass growth. way of implementing nutrient reduction pro? Mississippi basin and to restore and enhance Donald Boesch, a biological oceanograph- grams. The report notes that, just as declines naturally occurring denitrification er (nitrogen with the University of Maryland Center for in water quality increased over many years, removal) rates in the basin. Environmental Science in Cambridge, calls the recovery in the Gulf of Mexico and other sys? However, it's difficult to know preciselyChesapeake program a "qualified success, in tems will take many years. "The science of what level of cleanup to aim for in the that gulf, degradation or has stopped and is, to a cer? cultural eutrophication is past its infancy but indeed, in U.S. waters in general. tain Like extent, the being reversed." But he notes that the science of restoration of enriched systems Gulf of Mexico, many other bodies a strong such feeling as of ownership on the part of the is not," states the report. The authors go on to Pamlico Sound have been monitored public little was aor major factor in the bay's improve- stress that for recovery strategies to remain not at all, despite their economic significance. ment. "People just do not like the idea of'their effective, they must be accompanied by a "When we notice [problems with bay'hypoxia], being polluted," he says. "The Gulf of long-term commitment to continuing systems have already been altered to Mexico a signifi? is very different. Few people live there; research, including continued examination of cant degree," Diaz says. "By the time tiiey you can't have call it 'my coast.' The states [work? existing data such as hydrogeographic, chemi? drastic changes in aquatic communities ing on theand Chesapeake Bay] have a vested cal, and biological conditions and events in , these systems are altered. interest; for We the Mississippi, it's very different. the gulf; improved surveying to better quanti- don't know what prehypoxic levels Most were of the in agricultural sources [of nutrient fy the problem; and continued monitoring. the gulf." loading] are 1,000-1,500 miles away." The research, like the recovery of the gulf, Yet experience with hypoxia in other Elsewhere in the United States, programs may take decades, but both are necessary to countries has demonstrated not only the targeting specific nutrient loading sources the continued recovery of degradation result? potential consequences of prolonged water have begun to show results. Chlorophyll levels ing from human activities. quality degradation but also the potential for in Long Island Sound appear to be diminish- recovery. Multinational efforts are under way ing witii improvements in sewage treatment, Stephanie Joyce

Environmental Health Perspectives ? Volume 108, Number 3, March 2000 A 125

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