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W W F Briefing Paper: Dead Ocean Zones - a global Problem of the 21. century

Contents

Introduction 3

Eutrophication - the process leading to dead zones 4

W hy is eutriphication a problem? 4

Harmful algal Blooms and 6

W hat are the sources of nutrients? 7

W here are the global eutrophic and hypoxic areas? 9

The situation is alarming - but a complete picture may be even worse 10

The knowledge must improve 11

W hat W W F asks for 11

Sources 12

Dead Zones of the W orld - by Region 13

Acknowledgements 19

Im pressum Publisher: W W F Deutschland, Frankfurt/ Main Editor: Jochen Lamp (W W F) based on the reports from Mindy Sel- man et al. (W RI), Sybil Seitzinger et al. (State University of New Jer- sey), Sehstedt, Hansen et.a.l: BALANCE interim report 17, DHI, Co- penhagen) June 2008 Design: Anja Bruckbauer (W W F) ≤ 2008 W W Fœ

Cover photo: algae bloom from a satellite image, July, 11. 2005 ≤ NASA/ SMHI 2 W W F Germany

Introduction

For a number of years, the United Nations km× of the sea at short periods. Environmental Programme (UNEP) has observed the problem of oxygen depletion In the , once known as the in marine and coastal areas with growing world‘s larges , signs of recov- concern. Oxygen depleted zones œ or ery can be observed for some areas out- dead zones, are phenomena that occur in side the stagnant lifeless deepwater areas. some ocean areas as a natural process. However, during the last years the reports On the other hand, the Baltic Sea is an of dead zones that are the result of anthro- example for joint action of states: after a pogenic activities have increased: HELCOM2 decision to eliminate Euthrophi- cation hot spots from point sources in In 1995 Diaz and Rosenberg identified 44 1989, app. 38% of the Nitrate input from dead zones globally. In March 2004 in its point sources was reduced since, for phos- first Global Environment Outlook Year phates the result is even better: the 50% Book, UNEP reported for the first time, that goal was reached by improved wastewater there are some 150 recurring and perma- treatment in communities and industrial nent dead zones in seas worldwide. Only 4 plants. The Baltic Sea Action Plan also years later, a research group under the much focuses on and has leadership of the W orld Resource Institute set the goal of further reduction of yearly (W RI) did the first systematic comprehen- input of 135.00 tons of Nitrogen and sive assessment of the phenomenon.1 15.000 tons of Phosphorus by 2021 to The scientists around Mindy Selman, reach a reduction of algae blooms, dead Suzie Greenhalgh, Robert Diaz and Zach- zones and to have clear water in the sea. ary Sugg identified 415 areas worldwide that are experiencing some form of eutro- phication œ 169 of them classified as hy- poxic. These areas may cover only small bays and of limited area size, they can also cover areas up to some ten thou- of square kilometres.

This paper will give an overview of the problem and of the most concerned areas world wide as well as highlight the most concerned global marine areas. It is mainly based on the W RI findings, but also taking account of information from other sources.

Robert Diaz, the author of the complete list, estimates that the area of documented Dead Zones accounts for 150.000 to 200.000 km× but also states, that only 30% of the cases are systematically monitored and documented.

Seven of the Top ten largest areas are ac- cording to Diaz located in the Baltic Sea, covering according to the assessments of the Helsinki Commission (HELCOM) an area of 42.000 km× of permanent anoxic zones but can easily reach up to 90.000

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Eutrophication œ the process leading to dead zones

Eutrophication–the overenrichment of waters extent of eutrophication, the sources of nutri- by nutrients–threatens and degrades many ents, and the impact of eutrophication on eco- coastal ecosystems around the world. The two systems. most acute symptoms of eutrophication are hypoxia (or oxygen depletion) and harmful al- W ithin the past 50 years, eutrophication has gal blooms, which among other things can de- emerged as one of the leading causes of water stroy aquatic life in affected areas. Eutrophica- quality impairment. The W RI research identi- tion sometimes occurres as a natural process, fies over 415 areas worldwide that are experi- however in this paper the focus is only on ef- encing symptoms of eutrophication, highlight- fects of eutrophication caused by anthropo- ing the global scale of the problem genic influences. . Recent coastal surveys of the United States Of the 415 areas around the world identified as and Europe found that a staggering 78 percent experiencing some form of eutrophication, 169 of the assessed continental U.S. coastal area are hypoxic and only 13 systems are classified and approximately 65 percent of Europe‘s At- as —systems in recovery.“ lantic coast3 exhibit symptoms of eutrophica- tion. One of the most concerned seas is the Mapping and research into the extent of eutro- Baltic Sea. phication and its threats to human health and ecosystem services are improving, but there is In other regions, the lack of reliable data hin- still insufficient information in many regions of ders the assessment of coastal eutrophication. the world to establish the actual extent of eu- Nevertheless, trends in agricultural practices, trophication or identify the sources of nutrients. energy use, and population growth indicate To develop effective policies to mitigate eutro- that coastal eutrophication will be an ever- phication, more information is required on the growing problem.

W hy is eutrophication a problem ?

The rise in eutrophic and hypoxic events has atmospheric concentrations of carbon dioxide, been primarily attributed to the rapid increase the gas primarily responsible for global warm- in intensive agricultural practices, industrial ing, by approximately 32 percent since the on- activities, and population growth, which to- set of the industrial age. gether have increased nitrogen and phospho- rus flows in the environment. Human activities Before nutrients–nitrogen in particular–are have resulted in the near doubling of nitrogen delivered to coastal ecosystems, they pass and tripling of phosphorus flows to the environ- through a variety of terrestrial and freshwater ment when compared to natural values.4 By ecosystems, causing other environmental comparison, human activities have increased problems and a loss of biodiversity.6 Once nu- trients reach coastal systems, they can trigger a number of re- sponses within the ecosystem. The initial impacts of nutrient in- creases are the excessive growth of , m icroalgae (e.g., epiphytes and microphytes), and microalgae (i.e., seaweed).

These, in turn, can lead to other impacts such as:

Photo 1: Filam entous algae over- grow the brown algae and sea grass beds that dom inate the habi- tats in a healthy ecosystem ≤ W W F Askö, Sweden

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A shift in phytoplankton species composition, Loss of subaquatic vegetation as excessive creating favourable conditions for the develop- phytoplankton, microalgae, and macroalgae ment of nuisance, toxic, or otherwise harmful growth reduce light penetration. algal blooms.

Change in species composition and of Low dissolved oxygen and formation of hy- the benthic (bottom-dwelling) aquatic commu- poxic or —dead“ zones (oxygen-depleted wa- nity, eventually leading to reduced species di- ters), which in turn can lead to ecosystem col- versity and the dominance of gelatinous organ- lapse.7 isms such as jellyfish. The scientific community is increasing its Coral damage as increased nutrient levels knowledge of how eutrophication affects favour algae growth over coral larvae. Coral coastal ecosystems, yet the long-term implica- growth is inhibited because the algae outcom- tions of increased nutrient fluxes in our coastal petes coral larvae for available surfaces to waters are currently not entirely known or un- grow. derstood. W e do know that eutrophication di-

Figure 1: Conceptual m odel of eutrophication. The arrows indicate the interactions between different ecological com partm ents. Nutrient enrichm ent results in changes in the structure and function of m a- rine ecosystem s, as indicated with bold lines. Dashed lines indicate the release of hydrogen sulphide (H2S) and phosphorus, which is positively related to oxygen depletion. ≤ BALANCE Interim report No. 17

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many communities relying directly on coastal minishes the ability of coastal ecosystems to ecosystems for their livelihoods.8 provide valuable ecosystem services such as This means that a significant portion of the tourism, recreation, the provision of and world‘s population is vulnerable to the effects shellfish for local communities, sport fishing, of eutrophication in their local coastal ecosys- and commercial fisheries. In addition, eutrophi- tems. cation can lead to reductions in local and re- In the light of reduced availability of e.g. Phos- gional biodiversity. phorus it would be a waste of resources to dis- charge this fertilizer into the coastal waters Today nearly half of the world‘s population instead of using it cautiously for human food lives within 60 kilometres of the , with supply.

Harm ful s and Hypoxia

Two of the most acute and commonly recog- ences between surface and subsurface waters nized symptoms of eutrophication are harmful lead to stratification, limiting oxygen replenish- algal blooms and hypoxia. ment from surface waters and creating condi- Harmful algal blooms can cause fish kills, hu- tions that can lead to the formation of a hy- man illness through shellfish poisoning, and poxic or —dead“ zone.14 death of marine mammals and birds.9 Harmful algal blooms are often referred to as Three of the most well-known hypoxic areas —red “ or —brown tides“ because of the ap- are the of Mexico and the Black Sea and pearance of the water when these blooms oc- the Baltic Sea. The Gulf of Mexico has a sea- cur. One red event, which occurred near sonal hypoxic zone that forms every year in Hong Kong in 1998, wiped out 90 percent of late summer. Its size varies; in 2000, it was the entire stock of Hong Kong‘s fish farms and less than 5,000 km×, while in 2002 it was ap- resulted in an estimated economic loss of $40 proximately 22,000 km×. W hile the economic million USD.10/ 11 consequences of the Gulf of Mexico dead zone In the , blooms of the Algae Phaeo- are still unclear, concern over its increasing cystes beaten by the winds generate large size led to the formation of the Mississippi amounts of algae foam on the in River/Gulf of Mexico W atershed Nutrient Task some years. Force in 1997 to develop a strategy to reduce On the Swedish coast in 2005 large areas the five-year running average areal extent of w h e r e the Gulf of Mexico hypoxic zone to less than closed for 5,000 km×. bathing due The Black Sea, which was once the largest to blooms of dead zone in the world, had 26 commercially toxic cyano- viable fish species in the 1960s but only five b a cte species by the 1980s.15 The growth of the bloom ing Black Sea hypoxic zone was attributed to the during that intensification of agriculture in the former So- summer in viet Union. It was stated in 1990 that due to most parts of natural conditions and to the anthropogenic the Central inputs —the water is saturated with hydrogen Baltic Sea. sulphide at depth below 150 m and there is a Photo 2: Red Tide in the New lack of oxygen —… “as a result of all these fac- Zealand coastal waters ≤ Miriam Godney, NMA Science Hypoxia, con- tors some 87% of the sea is either hypoxic or sidered to be poisonous to life“16 It has been —in recovery“ the most se- since the economic collapse of Eastern Europe vere symptom of eutrophication, has escalated in the 1990s, which resulted in significant re- dramatically over the past 50 years, increasing ductions in fertilizer use. In recent years (year from about 10 documented cases in 1960 to at 2000) it is reported that nutrient contents in the least 169 in 2007.12/ 13 marine waters have reached œ at least for Phosphorus- the levels of the 60ies, and that Hypoxia occurs when algae and other organ- many hypoxic zones have been eliminated ac- isms die, sink to the bottom, and are decom- cording to scientific research cruises during posed by bacteria, using the available dis- 2003, 2004 and 2006. solved oxygen. and temperature differ-

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The Baltic Sea system Diaz contains 7 of the periodically or irregularly. Diaz estimates that larges dead zones, worldwide œ summing up to the total area of anthropogenic induced dead an area of more than 42.000 km× of sea bottom zones globally ranges between 150.000 km× permanently hypoxic and about 100.000km× and 200.000 km×.17

Photo 3: In coastal waters as this exam ple from Danish waters in 2002 shows fish kills can be caused by oxegen depletion and form ing SO2. ≤ BALANCE report No. 17

W hat are the sources of nutrients?

Agriculture, human sewage, urban runoff, in- treated, 14 percent in Latin America and the dustrial effluent, and fossil fuel combustion are Caribbean, and less than 1 percent in Africa.19 the most common sources of nutrients deliv- ered to coastal systems.18 Between regions, Atmospheric sources of nitrogen are also rec- there are significant variations in the relative ognized as a significant contributor20 of nutrient importance of each nutrient source. For exam- in coastal areas. Nitrogen from fossil fuel com- ple, in the United States and the European Un- bustion and volatilization from fertilizers and ion, agricultural sources (particularly animal manure is released into the atmosphere and manure and commercial fertilizers) are gener- redeposited on land and in water by wind, ally the primary contributors to eutrophication, snow, and rain. In the Chesapeake in the while sewage and industrial discharges, which mid-Atlantic region of the eastern United usually receive some treatment prior to dis- States, atmospheric sources of nitrogen ac- charge, are a secondary source. However, in count for a third of all controllable nitrogen that Latin America, Asia, and Africa, wastewater enters the Bay; similarly, in the Baltic Sea in from sewage and industry are often untreated Europe, atmospheric nitrogen accounts for a and may often be the primary contributors to fourth of all controllable nitrogen. eutrophication. It is currently estimated that only 35 percent of wastewater in Asia is W W F Germany 7

Current estimates identifying the sources of the global patterns of nutrient sources differ nutrients that reach coastal waters were con- substantially in the watersheds of the different ducted by Sybil Seitzinger for the Intergovern- river systems. Patterns vary depending on the mental Oceanographic Commission during the nutrients (nitrogen, phosphorus or carbon), its recent years. According to the models of Seitz- forms (organic or inorganic, diffuse or point inger et al. the amount of the airborne nutrients sources) and climate and landscape types. will increase substantially during the coming Especially, there is a considerable spatial decades (for China and India doubling from variation in the relative contribution of anthro- about 200 to more than 500 kgN /km×/yr.21 pogenic versus natural sources of nutrients According to the findings of Seitzinger et al.18 exported to the sea areas. W hile globally natu-

Figure 2: Atm ospheric Deposition, predicted for 2050 (kg N/ km × /year) ≤ Seitzinger, 2006

Figure 3: Hot spots for river nutrient yield (kg C,N or P km ×yr). River basins with the highest predicted inorganic P and N yields (DIP,DIN) (top 10% globally) are shaded green. River basins with the highest predicted organic C,P and P (DOC,DOP,DON) yields (top 10% globally) are shaded blue, and river basins with the highest predicted point source organic C, N and P (POC, PON, PON) yields (top 10% globally) are shaded pink. Basins with brownish or purple cast (e.g. basins in Central Am erica and are basins where m ultiple nutrient form s are predicted to fall within the top t10% globally. ≤ Seitzinger, 2006 ral N and P in organic form from diffuse dicted to originate from anthropogenic sources. sources account for approximately 75 percent, there are some areas, (e.g. in southern Asia) Nevertheless, there are some river basin hot where more than 50 percent of these nutrients spots indicated in the figure 3 that show that all originate from human sources, in western forms of nutrients enter very limited sea areas Europe and parts of the United States about 50 like from the of Southern Asia, Indone- percent of organic nitrate and more than 25 sia and Japan as well as parts of Central percent of organic diffuse phosphorus are pre- America. Here the threats of forming dead 8 W W F Germany

zones are very high. In Japanese basins the For parts of Europe and the northeast United anthropogenic input is very high. States organic nitrate and phosphorus are also assumed to be of anthropogenic sources.

W here are the global eutrophic and hypoxic areas?

W RI research identified 415 eutrophic and Docum ented hypoxic areas: Areas with sci- hypoxic coastal systems worldwide (Figure entific evidence hat hypoxia was caused, 4).22 at least in part, by nutrient overenrichment. Of these, 169 are documented hypoxic areas, This category includes the most recent list 233 are areas of concern, and 13 are systems of hypoxic areas compiled by Diaz in recovery. (excluding hypoxia caused by natural up- The coastal areas reported as experiencing welling of nutrients), as well as some 20 eutrophication are steadily growing. This is be- additional systems identified by the W RI cause of the increasing prevalence of eutrophi- research. cation and advances in identifying and report- Areas of concern: Systems that exhibit effects ing eutrophic conditions. of eutrophication, such as elevated nutrient levels, elevated chlorophyll a levels, harm- The first comprehensive list of hypoxic zones ful algal blooms, changes in the benthic was compiled by Diaz and Rosenberg in 1995 community, damage to coral reefs, and fish and identified 44 documented hypoxic areas.23 kills. These systems are impaired by nutri- Twelve years later, there are 169 documented ents and are possibly at risk of developing hypoxic areas, a nearly four- fold increase. The list of hy- poxic areas assembled by Diaz was com- piled from sci- entific litera- ture and identi- fied the major- ity of docu- m ented hy- poxic areas.

However, the list did not in- clude areas w ith sus- pected– but not docu- Figure 4: Coastal eutrophic and hypoxic areas of the W orld ≤ W RI 2008 m e n te d – hypoxic events or systems that suffer from hypoxia. Some of the systems classified as other impacts of eutrophication such as nui- areas of concern may already be experi- sance or harmful algal blooms, loss of encing hypoxia, but lack conclusive scien- subaquatic vegetation, and changes in the tific evidence of the condition. structure of the benthic aquatic community (for System s in recovery: Areas that once exhib- example, decline in biomass, changes in spe- ited low dissolved oxygen levels and hy- cies composition, and loss of diversity). poxia, but are now improving. For example, To supplement this list of hypoxic zones, the the Black Sea once experienced annual authors undertook an extensive literature re- hypoxic events, but is now in a state of re- view to catalogue systems experiencing any covery. Others, like Boston Harbor in the symptoms of eutrophication, including–but not United States and the Mersey in limited to–hypoxia.24 the United Kingdom, also have improved water quality resulting from better industrial The eutrophic areas identified were catego- and waste-water controls. rized as: W W F Germany 9

The situation is alarm ing - but a com plete picture m ay be even worse

The actual extent and prevalence of eutrophi- for the Protection of the Marine Environment of cation in many regions is only beginning to be the North-East Atlantic (OSPAR) highlighted studied. As a consequence, data do not exist the variability in quality and availability of moni- or are not publicly available for many areas toring data among the various European coun- that may be suffering from the effects of eutro- tries.25 phication. In addition, the data that do exist are often inconsistent in terms of parameters Several coastal areas lacked dissolved oxygen measured, indicators used, and the scale at measures and many of the secondary effects which data are reported. of eutrophication, such as fish kills and changes in the benthic community, were not Given the state of global data, the number of extensively monitored. The U.S. National Oce- eutrophic and hypoxic areas around the world anic and Atmospheric Agency‘s (NOAA) Na- is expected to be greater than the 415 listed tional Estuarine Eutrophication Assessment here. program, which conducted national eutrophica- tion surveys in 1999 and 2007, experienced The most underrepresented region is Asia. data issues similar to those encountered in the Asia has relatively few documented eutrophic OSPAR survey. Of the 141 U.S. and hypoxic areas despite large increases in evaluated in 2007, 30 percent lacked adequate intensive farming methods, industrial develop- data for assessing their eutrophication status. ment, and population growth over the past 20 years. Africa, Latin America, and the Carib- Most systems identified as hypoxic or eutrophic bean also have few reliable sources of coastal also lack detailed data on the sources of nutri- water quality data, making it difficult to assess ent impairments and the relative contribution of the true level of eutrophication. each source. Some systems that have devel- oped detailed nutrient budgets include the The scale at which data for eutrophic areas are Chesapeake Bay, Baltic Sea, Black Sea, Gulf reported varies greatly. For example, red tides of Mexico (Mississippi-Atchafalaya plume), and and other eutrophic events are frequently re- Tampa Bay. The absence of detailed nutrient corded in the South China Sea, Yellow Sea, budgets for the majority of eutrophic and hy- and Bohai Sea. However, the actual extent of poxic systems around the world highlights the eutrophication or hypoxia in specific bays and lack of concerted research efforts in these ar- estuaries within these systems is unknown. eas, compromising the ability to effectively ad- Therefore, these areas are coarsely recorded dress and manage nutrient overenrichment. in Figure 4 and most likely represent several affected bays and estuaries along the Chinese coast. Conversely, within the well-studied Chesa- peake Bay system, there are 12 distinct and documented eutro- phic and hypoxic zones.

The United States, European Un- ion, and Australia–all of which have each undertaken compre- hensive coastal surveys in the past five years–have the most comprehensive coastal data on eutrophication. However, even within the United States and Europe, the quality, consistency, and availability of water quality data varies. For example, in Europe, the coastal survey coor- Photo 4: Bloom ing blue-green algae in the Baltic Sea ≤ Anders Mo- dinated through the Commission dig

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The knowledge m ust im prove

Improving our knowledge of where eutrophica- to identify likely eutrophic areas. tion is occurring, the sources contributing to the Finally, it is not enough to fill the scientific problem, and the effects of eutrophication on knowledge gaps. Researchers and policy- marine ecosystems and human communities makers need tools and information to base de- ultimately influences the ability of policy- cisions on. Such tools include: makers to decide where and how resources • W atershed models to assess nutrient delivery can be used most effectively to address eutro- and ecosystem impacts; phication. • Nutrient balance assessments to determine the sources of nutrients and relative contribu- W ithout better data and information, communi- tion of each source; ties cannot effectively manage coastal ecosys- • Regional and international online information tems and address land-based sources of pollu- portals for compiling and sharing water quality tion. Specifically, time series monitoring data– information and research; on nutrient levels, chlorophyll a (as an indicator • Nutrient loss estimation tools; and of the presence of phytoplankton), and dis- • Tools to help assess the effectiveness of al- solved oxygen–as well as eutrophication re- ternative scenarios for reducing nutrient inputs. sponse parameters–such as loss of sub- Implementation of these tools is especially aquatic vegetation, fish kills, and algal needed to estimate coastal impacts and target blooms–are needed to evaluate the extent appropriate policy responses in countries and and degree of eutrophication. regions where actual monitoring data are Moreover, comparable and joint standards to scarce. classify and define eutrophic waters are needed to increase the transparency, consis- Eutrophication is an issue that requires greater tency, and comparability of water quality infor- attention by governments and society in gen- mation. For example, currently no common eral. Left untouched, it may have dire conse- definition of —hypoxia“ exists and the interpreta- quences for many ecosystems, the food webs tion of what is hypoxic can vary widely from that they support, and the livelihoods of the place to place. populations that depend on them. To get a bet- ter grasp on the immediate and long-term con- In countries or regions where robust and sys- sequences of eutrophication, we need more tematic monitoring programs are unlikely to be resources and better information. Improving implemented due to limited resources, it would our knowledge and information on eutrophica- be beneficial to develop credible and consis- tion is the first step in developing robust policy tent simple proxies for water quality (such as measures to begin reversing or halting its im- turbidity or sulphide smell) that could be used pacts.

W hat W W F wants: W orldwide: Actions to reduce eutrophication Good knowledge for better decisions: are urgently needed regardless of com plete ñ knowledge: The state of eutrophication in coastal ñ waters must be regularly monitored and Consequent with re- methods and definition internationally duction of nutrients in all urban areas agreed. and river catchments, ñ In Asia, Africa, and Latin Am erica: Reconstruction of natural as ñ An initial assessment of eutrophication nutrient traps, ñ in coastal areas is necessary. Simple Fundamental changes in the agricultural indicators for the assessment of Eutro- practice to strictly avoid nutrient runoff phication and impacts on ecosystem from fertilizers, ñ health need to be developed and moni- Ban of W ashing detergents that use toring on a regular base has to be estab- phosphorus lished and exchanged globally and re- ñ Reduction of airborne nutrients (low gionally. emission standards for cars, ships and In the United States, Europe, and Australia: households, speed limits) ñ coastal zone assessments have to con- In the EU context: tinue and methods be internationally ñ Change of the Common Agricultural Pol- agreed and applied for all seas. icy to low nutrient production Inform ation about the consequences of eutro- ñ Introduction of a Phosphate Directive for phication must be disseminated and enlarged. affected sea catchments

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Sources

1. Selman, Mindy, Suzie Greenhalgh, Robert Diaz http://www.europe.culturebase.net/ and Zachry Sugg: Eutrophication and Hypoxia in contribution.php?media=307 (accessed December Coastal Areas œ A global assessment of the state 30, 2007) of knowledge, W orld Resource Intitute W RI, , 16. Viktor Karamushka : Is the Black Sea recovering? W ashington DC, USA March 2008 In Europe now, 2. HELCOM Secretariat: Towards a Baltic Sea unaf- 17. Personal note to the editor. May 2008 fected by Eutrophication, HELCOM overview 2007, 18. Seitzinger, S.P., J.A. Harrison, E. Dumont, A.H.W . HELCOM Ministerial Meeting, Krakow, Poland Beusen, and A.F. Bouwman (2005)Sources and 15.November 2007, pp.16-18 delivery of carbon,, nitrogen, and phosphorus to 3. Bricker, S. B., Longstaff, W . Dennison, A. Jones, the coastal zone: An overview of Global Nutrient K. Boicourt, C. W icks, and J. W oerner. 2007. Ef- Export from W atershed (News) models and their fects of Nutrient Enrichment in the Nation‘s Estuar- application , Global Biogeochemn. Cycles, 19, , ies: A Decade of Change. NOAA Coastal Ocean Rutgers/NOAA, State University of New Jersey, Program Decision Analysis Series No. 26. Silver New Brunswick, NJ,USA p.7-11 Spring, MD: National Centers for Coastal Ocean 19. Howarth, R. and K. Ramakrrshna. 2005. —Nutrient Science. Online at: http://ccma.nos.noaa.gov/ Management.“ In K. Chopra, R. Leemans, P. publications/eutroupdate/ Kumar, and H. Simons, eds. Ecosystems and Hu 4. Howarth, R. and K. Ramakrrshna. 2005. —Nutrient man W ellbeing: Policy Responses. Volume 3 of the Management.“ In K. Chopra, R. Leemans, P. Millennium Ecosystem Assessment (MA). W ash Kumar, and H. Simons, eds. Ecosystems and Hu- ington, DC: Press man W ellbeing: Policy Responses. Volume 3 of the 20. Spokes, L. J., and T. D. Jickells. 2005. —Is the at- Millennium Ecosystem Assessment (MA). W ash- mosphere really an important source of reactive ington, DC: Island Press. nitrogen to coastal waters?“ Re 5. National Oceanic and Atmospheric Administration search 25: 2022œ2035. (NOAA). —Global W arming: Frequently asked ques- 21. Sybil P. Seitzinger; Presentation for the Intergov- tions.“ Available at: http://lwf.ncdc.noaa.gov/oa/ ernmental Oceanographic Commission IOC/UNEP climate/globalwarming.html. (accessed January 15, GPA/UNEP MEDPOL W orking Group: Global Pat- 2008) terns of human Activities on Land and Nutrient 6. Galloway, J.N, J.D. Aber,, J.W . Erisman, S.P. enrichment of Coastal Marine Ecosystems œ Cur- Seitzinger, R.W . Howarth, E.B. Cowling, and B.J. rent conditions and future projections , slide 21. Cosby. 2003. —The Nitrogen Cascade.“ Bioscience 22. Region-specific maps as well as the data used to 53( 4): 341œ356 create these maps is made available on W RI‘s 7. For a discussion on the impacts of eutrophication website, www.wri.org/project/water-quality on coastal ecosystems, see Mee, L. 2006. 23. Diaz, R. and R. Rosenburg. 1995. —Marine benthic —Reviving Dead Zones.“ Scientific American 295 hypoxia: a review of its ecological effects and the (5): 79œ85. behavioural responses of benthic macro fauna.“ 8. UN Chronicle Online Edition. —Risks, Untreated Oceanography and : an Annual Sewage Threatens Seas, Coastal Population.“ Review 33: 245œ303. http://www.un.org/Pubs/chronicle/2003/ 24. The primary data sources include: Diaz, R. J., J. issue1/0103p39.html. (accessed January 15, 2008) Nestlerode, and M. L. Diaz. 2004. —A global per- 9. Anderson, D. M., P. M. Gilbert, and J. M. spective on the effects of eutrophication and hy- Burkholder. 2002. —Harmful Algal Blooms and Eu- poxia on aquatic biota.“ In G. L. Rupp and M. D. trophication: Nutrient Sources, Composition, and W hite, eds. Proceedings of the 7 International Consequences.“ Estuaries 25 (4b): 704œ726. Symposium on Fish Physiology, Toxicology, and 10. Terra Daily Online Edition. —Hong Kong red tide W ater Quality, Tallinn, Estonia, May 12-15, 2003. spreads,“ (June 10, 2007). http:// Athens, Georgia: U.S. Environmental Protection www.terradaily.com/reports/ Agency, Ecosystems Research Division (EPA 600/ Hong_Kong_Red_Tide_Spreads_999.html R-04/049). (accessed February 8, 2008). 25. OSPAR called for the uniform assessment of 11. Lu, S., and I. J. Hodgkiss. 2004. —Harmful algal coastal waters by signatory countries. Signatory bloom causative collected from Hong Kong wa- countries to the 1992 Oslo-Paris Convention for ters.“ Hydrobiologia.512(1-3): 231-238 the Protection of the Marine Environment of the 12. Hypoxia is generally defined as having a dissolved North-East Atlantic (OSPAR Convention) include oxygen concentration of 2.0 milligrams per liter or Belgium, Denmark, France, Germany, Ireland, The less. Netherlands, Norway, Portugal, Spain, Sweden, 13. Diaz, R. J., J. Nestlerode, and M. L. Diaz. 2004. —A and the United Kingdom. global perspective on the effects of eutrophication 26. Sehested Hansen, Ian, Nina Keul ,Jacob Tornfeldt and hypoxia on aquatic biota.“ In G. L. Rupp and Sørensen , Anders Erichsen and Jesper H. Ander- M. D. W hite, eds. Proceedings of the 7th Interna- sen :Baltic Sea Oxygen Maps 2000 2006 BAL- tional Symposium on Fish Physiology, Toxicology, ANCE Interim Report No. 17, November 2007, DHI and W ater Quality, Tallinn, Estonia, May 12-15, W ater œ Environment œ Health, Copenhagen 2003. Athens, Georgia: U.S. Environmental Protec- 27. Xianshi, Jin, Yellow Sea Fisheries Research Insti- tion Agency, Ecosystems Research Division (EPA tute, Chinese Academy of Fishery Sciences, Qu- 600/R-04/049). ingdao, China, in: Estuarine, coastal and shelf 14. Rabalais, N. N., and R. E. Turner. 2001. Coastal science, vol.59, no° 1, pp.163-171, 2004 hypoxia consequences for living resources and ecosystems. W ashington, DC: American - physical Union. 15. Europe Now|Next. —Is the Black Sea recovering?“

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Dead Zones of the W orld œ by Region

EUROPE

Figure 5: Coastal eutrophic and hypoxic areas of Europe ≤ W RI 2008

This map identifies 168 eutrophic and hypoxic the North-East Atlantic (OSPAR), coordinated coastal areas in Europe. Fifty-nine of these are eutrophication assessment is still hampered by documented hypoxic areas, 106 are areas of inconsistent reporting methods between coun- concern, and 3 are improved systems that are tries and sometimes inconclusive data for de- in recovery. Although relatively comprehensive termining eutrophic status. It is worth noting the geographically thanks to multinational surveys substantial ecological improvements made in such as those carried out by the Commission the Black Sea, which was formerly one of the for the Protection of the Marine Environment of most notorious hypoxic areas but is now in re- covery. Seven of the world larges known hypoxic areas are located in the Baltic Sea. This is the reason why the Baltic Sea is treated here with an additional description.

Photo 5: Mats of blue-green algae covered large parts of the Baltic Sea ≤ Anders Mo- dig

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Excurse: Baltic Sea areas can be concerned. This happened in 2002 when mass mortality of dwelling The oxygen situation in the Baltic Sea was animals and occurred in large parts of documented and modeled for 2000 to 2006 in the western Baltic Sea and in 2005 when a a recent report published in 2007 in the frame- large algae blooms of blue-green algae cov- work of the EU Project BALANCE. The results ered large areas along the Swedish East coast in this paper originate mainly from the BAL- in the Central Baltic Sea. ANCE Report No. 17.26 The results from the Globally, the Baltic accounts for the larges hy- individual years document the extent and vari- poxic areas documented world wide. According ability of the oxygen depletion. to the assessments of the Helsinki Commis- sion in 2006, about 42.000km× of the sea bot- Due to its hydrology (enclosed sea with limited tom are permanently affected by oxygen deple- water exchange with the Atlantic Ocean) the tion, in some years this can sum up 100.000 Baltic Sea is very sensitive to oxygen deple- km× . In the Baltic Sea action Plan, the Baltic tion. In the of the sea, regularly Sea countries have committed to reduce the haloclines form that separate the different wa- input of P by 15.000 t and N by 135.000 t an- ter layers from each other and prevent the mix- nually from 2016 on. The long-term objective of ing of oxygen richer water with low oxygen wa- the Baltic Sea Action Plan is to reduce the ter. The Helsinki Convention (HELCOM) the dead zones of the Baltic to an area of app. oldest global Regional Seas Convention, has 30.000 km× which is regarded as the historical estimated an area of oxygen-depleted bottom natural size under Baltic Sea conditions.

From the BALANCE report for the various areas the following conclu- sions can be drawn:

Skagerrak The proper of Skagerrak is not suffering from low oxygen condi- tions in any of the assessment years. Along the Swedish coast of Skagerrak local signs of reduced oxygen are seen in several years and near the Danish coast local signs are seen in 2001.

Kattegat The assessment shows that most parts of Kattegat have suffered from oxygen depletion once or more times during the assessment period. Only the central part of the northern Kattegat seems not to be affected. The impact includes down to less than 1.5 ml/l in the southernmost part of Kattegat and some way up along the Swedish Figure 6: Modelled distribution of frequency for extent of m ini- coast and a large part of this area m um oxygen condition, showing the num ber of years within is subjected to oxygen depletion seven years 2000–2006 where m inim um bottom oxygen be- every year. com es blow 3 m l O×/ l ≤ BALANCE Interim report No. 17 W estern Gotland Basin zones of the sea for the early 20th century of The basin west of Gotland is also subjected to about 10.000 km×. Since the seventies of the very critical oxygen conditions every year with last century the HELCOM states monitor the the years 2000, 2003 and 2004 being the most oxygen content in the water. In 2006 an area of critical years. app. 42.000km× was reported that can be re- garded as a permanently oxygen free Dead Gulf of Riga Zone. Periodically œ dependent on stagnation Only the central part of the Gulf of Riga seems phases and seasonal events œ by far larger to be subjected to depletion every year, 14 W W F Germany

whereas most of the offshore area is subjected to depletion at least once in the seven year period. Year 2001 seems to have been the less critical year and year 2002 among the most critical years. Some critical con- centrations are also seen close to the coast.

Gulf of Finland In the Gulf of Finland the inner- most part and the deeper part all the way out are suffering from depletion every year. The variability from year to year is not large, but the years 2001, 2002 and 2003 seem to have had the most critical conditions.

Åland Sea The sea around the Åland is probably not sufficiently well resolved in the applied model to assess the bottom oxygen conditions, as the model applied a 9 nm hori- zontal resolution here. The re- Figure 7: Modelled distribution of every year bottom oxygen deple- sult showing no significant criti- tion area for the entire period 2000–2006, showing where oxygen cal oxygen parts may thus be a is low each year in the analysis period ≤ BALANCE report No. 17 too optimistic assessment. period, not even in the deepest parts in the Gulf of Bothnia northern end. The Bothnian Sea does not seem to have suf- fered from oxygen depletion in the assessment

The Black Sea shed are carried by the Po River into the Adri- The Black Sea was in the 1970ties and 80ies atic Sea, annually. known to be the most eutrophicated Sea in the world, within 5 years an area of the size of Bel- North Sea gium changed into a dead zone, fed by inten- The North Sea many rivers discharge their sive agricultural nutrients. After the political loads. Especially the Rhine and the highly in- changes in Eastern Europe, the agriculture tensive agricultural areas for the Netherlands , collapsed and fertilizer use dropped down. This Belgium, France, the UK and Germany are was the reason for a recovery of the oxygen- discharging into this sea area. Due to airborne ated water body of the Black Sea. Neverthe- sources and high population densities anthro- less today the Fertilizer Industry estimates an pogenic input of nutrients is high. increase of fertilizer market in Eastern Europe by 30% in the years to come. If not precautions The German recorded hypoxia of of nutrient management schemes will be 15.000km× in 1982, which accounts for one of introduced, this means the threat of new dead the larges areas in the world zones in the Black Sea and in the Baltic Sea as well. Seas around Ireland In the Celtic Sea, the Irish Sea and in many /Mediterranean Irish waters many areas of concern according The northern most part of the Adriatic Sea with to the Diaz list were recorded during the last 20 the lagoon of and the Po river discharg- years. ing into it has faced hypoxia several times. About 4300 kg Nitrate per km× of the water-

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NORTH AMERICA AND CARIBBEAN

Figure 8: Coastal eutrophic and hypoxic Areas of North Am erica and the Caribbean ≤ W RI 2008

This map identifies 131 eutrophic and hypoxic subsystems are classified as recovering, still coast zones in North America and the Carib- 12 areas are regarded as hypoxic or docu- bean. Sixty-two have documented hypoxia, 59 mented eutrophic zones. are areas of concern, and 10 are systems in recovery. Despite having many well-studied The Gulf of Mexico (US part) systems such as the Chesapeake Bay, which The Gulf of Mexico is known as the second has 12 distinct eutrophic and hypoxic zones, largest of the top 10 global Dead Zones: in the water quality data in the U.S. still have room for worst years the hypoxic zone was 22.000 km× improvement. In 2007 the U.S. National Oce- large. To reduce the area to 5.000 km, what is anic and Atmospheric Agency‘s (NOAA) Na- the governments goal, a reduction of Nitrogen tional Estuarine Eutrophication Assessment fertilization of about 45% would be needed in program evaluated the eutrophic status of 141 the river catchment of the Mississippi. estuaries, yet 30 percent lacked adequate data In the Gulf area, several hypoxic events have to make a definitive assessment. As with many been recorded since. This led among others to less-developed regions of the world, data on losses for the shrimp fisheries as shrimps flee eutrophication for the Caribbean is generally from the oxygen depleted areas or have to ex- sparse, making this map likely an underrepre- ist at their ecological capacity limits. sentation of the actual number of eutrophic and hypoxic areas. Areas The river basins that discharge nutrients from Chesapeake Bay the Central American watershed account The Chesapeake Bay in the mid-Atlantic region among the top ten areas with the highest nutri- of the eastern United States is one of the best ent loads world wide. Even though not proven studied sea areas suffering from hypoxia and by detailed measurements and monitoring eutrophication. Here atmospheric sources of data, there is reason for concern that in the nitrogen account for a third of all controllable Caribbean coastal areas more eutrophicated nitrogen that enters the Bay Even though some zones are to be found.

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SOUTHAMERICA

This map identifies 25 eutro- phic and hypoxic zones, with 3 having documented hy- poxia and 22 areas of con- cern. Most are found in Bra- zil, Chile, and Peru. This is most likely an undercount for the continent given recent increases in nutrient delivery to coastal waters related to agriculture, growing industry, fossil fuel combustion, and population growth. It is esti- mated that only 14 percent of wastewater, a key source of nutrients, is treated in Latin America and the Caribbean. Improved water quality moni- toring and assessment is re- quired to identify problem areas and their sources, and to develop strategies to re- duce eutrophication.

Figure 9: Coastal eutrophic and hypoxic areas of South Am erica ≤ W RI 2008

AUSTRALIA/ OCEANIA This map identifies 36 eutrophic coastal zones; 9 with documented hypoxia and 27 areas of concern. The majority of information on eutrophic areas in Australia is de- rived from a national water quality audit conducted in 2001.

New Zealand's Rodney is among the top 10 hypoxic zones of our globe. . In Australia mainly the areas in the South, near Perth and around Tasmania are concerned.

Figure 10: Coastal eutrophic and hypoxic areas of Australia/ Oceania ≤ W RI 2008 W W F Germany 17

AFRICA

This map identifies only 20 eu- trophic coastal zones in all of Africa, of which 8 have docu- mented hypoxia and 12 are areas of concern. There are undoubtedly many more, but a lack of reliable water quality data makes it difficult to assess the true scope of eutrophica- tion in Africa.

Figure 11: Coastal eutrophic and hypoxic areas of Africa ≤ W RI 2008

SOUTH ASIA able at a finer scale. Because of large in- creases in intensive farming methods, in- dustrial development, and population growth in Asia over the past 20 years, we know that eutrophication and hypoxia are greatly underrepre- sented in this map. Better water quality monitoring and as- sessment in China and throughout Asia are needed in order to understand the full extent and nature of eutrophication in Asia.

W ith regard to the estimates of Seitz- Figure 12: Coastal eutrophic and hypoxic areas of South Asia ≤ W RI 2008 inger et al., the rev- erie input of nutrients This map identifies just 24 eutrophic coastal is very high in the coastal waters of Indonesia areas with documented hypoxia and 9 areas of and also for many Chinese coastal areas. concern within Asia. Forty-two percent of these Changes in fish community structure, biomass areas are located in Japan, where monitoring and biodiversity in the Bohai Sea are described of eutrophication is well advanced. In China, from four summer bottom trawl surveys con- some hypoxic and eutrophic systems are iden- ducted between 1959 and 1998. The mean tified at a coarse scale. For example —South catch in 1998 declined to only 4.0% , 4.3% and China Sea“ and —Bohai Sea“ are represented 3.6 % of that in 1959, 1982 and 1992, respec- as single points because data were not avail- tively.27 18 W W F Germany

Acknowledgem ents

W W F thanks Mindy Selman from the W orld Resource Institute (W RI) in W ashington DC, USA, for allowing W W F to use the data from the W RI-Policy Note no.1 2008 : ‚Eutrophication and Hypoxia— as a backbone for this briefing report. W e also thank Mindy Selman for reviewing earlier drafts of this re- port and for valuable contributions during preparation. W W F acknowledges Robert Diaz, College of W illiam and Mary, Virginia Institute of Marine Science, Virginia, USA and Laurence Mee, University of Plymouth, UK, for contributing with help and information on specific areas. Additionally, we thank Sybil Seitzinger, of the Rutgers State University of New Jersey, Brunswick, New Jersey, USA, for contributing with valuable information about the nutrient inputs from global watersheds and for the use of the graphs from her publications.

Photo 6: Algae bloom s in the open Baltic Sea ≤ Anders Modig W W F Germany 19

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