Marine dead zones

MARINE DEAD ZONES

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MARINE DEAD ZONES

W.A.D.M.WIJETHILAKEAS2009167

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Outline What is Marine Dead Zone (MDZ) ? History of Ocean Dead Zones Dead zones around the world How this happens? What causes hypoxia? When does the hypoxia occur? Environmental, Social & Economic effects What can be done? HABHRCA QUIZ TIME Conclusion Acknowledgement References

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Marine Dead Zones W.A.D.M.Wijethilake AS2009167

What is Marine Dead Zone (MDZ) ?

NOAA

Hypoxia = Reduced level of oxygen in the water

Less oxygen dissolved in the water

Occur naturally OR created or enhanced by human activity.

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What is Marine Dead Zone (MDZ)? cnt.

Many physical, chemical, and biological factors combine to create dead zones

Nutrient pollution is the primary cause – Human encroachment

East Coast, the Gulf of Mexico (U.S) & Great lakes

Second largest - Northern Gulf of Mexico

A significant portion of the world's population - nearly half of which lives within 40 miles of a coast is vulnerable to harmfully over-enriched ecosystems,"

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The technical term for low oxygen = hypoxia.

When oxygen concentration falls below 2mg/l = hypoxic area

The term for no oxygen is = anoxia. Anoxia = 0 mg/l dissolved oxygen

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Marine Dead Zones W.A.D.M.Wijethiake AS2009167


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Dead zones in the coastal oceans have spread exponentially since the 1960s and have serious consequences for ecosystem functioning.

First recorded in the 1970s off the coasts of developed countries.

Dead zones were originally discovered in the, US, Chesapeake Bay Kattegat Strait in Scandinavia Mouth of the Baltic Sea Black Sea, Northern Adriatic Sea.

Currently about 400 ocean DZs worldwide,

Ranging in size from 1 square km to 20,000 square Km.

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HAPPY NEWS

Dead zones are reversible. The Black Sea dead zone, previously the

largest in the world, largely disappeared between 1991 and 2001

After fertilizers became too costly Fishing had again became a major

economic activity in the region

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BUT

From 1985 to 2000, theNitrogen in North Sea DZ had reduced by 37%

BECAUSE,,, Policy efforts by countries on the Rhine

River , they reduced Sewage and Industrial emissions of Nitrogen into

the water.

Other cleanups have taken place in the US along the

Hudson River and San Francisco Bay

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Hood Canal

Fjord forming the western lobe & one of the four main basins in the state of Washington

NATURAL WATER WAY

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In 2008, 415 Dead Zones Were Identified NASA Releases New Map of Aquatic

Dead Zones July 23, 2010

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Red circles on this map show the location and size of many of our planet’s dead zones.

Black dots show where dead zones have been observed, but their size is unknown.

It’s no coincidence that dead zones occur downriver of places where human population density is high (darkest brown)

Naturally occurring low-oxygen zones are regular features in some parts of the ocean. (Coastal upwelling areas)

However, these zones may grow larger with the additional nutrient inputs from agricultural runoff.

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Two famous hypoxic regions are:

The Gulf of Mexico, fed by the overly-enriched Mississippi River

2. The Black Sea, which is currently recovering - Soviet area


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Step 1 Eutrophication starts with farmers

spreading fertilizers rich in Nitrates and Phosphates on their fields.

When it rains much of the fertilizers are washed into large bodies of water

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Step 2 The added nutrients then cause an

increase in plant and algae growth

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Step 3: The algae begins to grows in such large

quantities that sunlight is blocked from the lower levels of ocean.

Less light means that species of plants and animals are only able to live at certain depths in the water due to lack of sunlight.

Step 4 Like all other organisms the algae eventually start

to die and the fall to the bottom of the ocean.

There bacteria attempt to breakdown the decomposing matter

But in the process they consume large amounts of oxygen and leave the water uninhabitable for many species such as fish.

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2 Causes

Natural Human induced

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Natural factors Human induced

Slow water circulation & mixing

Altering the river flows, landscapes

Changes in weather Altering the marine life

High growth of Algae Adding excess nutrients to the waters that can fuel extra Algae growth

Loading of Carbon & Nitrogen

Adding extra carbon to the ecosystem

Changes in the native marine life composition

Influencing climate change

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Natural Factors

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Sometimes Eutrophication is human – induced

The culprits are: Agricultural fertilizer Domesticated animal manure Industrial & urban runoff Sewage Atmospheric nitrogen

These waste products have caused nitrogen and phosphorus in to coastal areas in the last fifty years ago.

In Europe and the U.S. fertilizer and manure are the main sources, because much of their sewage is treated before entering the water system.

In regions like Africa, Latin America, and Asia where sewage and industrial waste are rarely treated, these wastes provide larger sources of nitrogen and phosphorus.

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There are several causes of ocean pollution including oil pollution, marine debris, toxic materials, and ocean dumping and mining.

Oil pollution is not only caused by large devastating tanker spills, it is also caused through runoff from land and industrial wastes & natural seepage which find their way to the ocean through drains.

Other causes include intensive farming, septic tank, pesticide, animal dung, household waste,waste water, nuclear waste... etc


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Hypoxic conditions were disrupted in the fall by tropical storms or cold fronts

Associated with increased wind and wave

action, which increases mixing in the entire water column.

This mixing replenishes oxygen concentration from the surface to the bottom of the water column.

The dead zone usually forms in the spring and summer

When water and air temperatures begin to rise.

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Environmental Social Economic

This eventually sparks the eutrophication process.

Marine life dies or suffers serious health problems.

Algal blooms create toxins, such as mercury or PCBs (Polychlorinated Biphenyls), that get absorbed by the sea life.

Humans are exposed to toxins through contaminated fish or water.

Eutrophication is greatly caused by contaminated local water from factories, farms, sewage, homes, etc., entering the ecosystem and disturbing its cycles.

The fish industry takes the greatest his in terms of economic effects caused by eutrophication.

Dwindling (decline) fish populations will force fishing companies.

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As well as marine animals, the problem greatly affects human communities, which rely on the coast and its resources for their livelihoods.

For example, a massive algae bloom in 1998 coast Hong Kong $40 million USD as it wiped out almost the entirety of Hong Kong's fish farms.

Dead zones can also effect……

Benthos,1. Stressed or die2. Decreased diversity3. Degraded environment

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Programs and initiatives are being implemented by the UN Environment Program and the US Environmental Protection Agency.

The National Resources Defense Council created a bill called OCEANS 21(the Oceans, Conservation, Education, and National Strategy for the 21st Century Act).

In Georiga, GreenLaw works to challenge industry and government actions that have compromised the environment.

Solutions for today

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- The Black Sea was once the largest dead zone in the world, but during 1991-2001, fertilizers stopped entering the ecosystem resulting in a reversal. The sea naturally restored its equilibrium.

- Solutions for preventing eutrophication is removing algae growth by means of filtration.

This would be effective but costly.

Solutions for the future Stop the use of fertilizers ! - There other means of fertilizing crops, e.g. compost

What Can be Done to Remediate the Problem?

Solutions include:

Using fewer fertilizers and adjusting the timing of fertilizer applications

Control of animal wastes

Monitoring of septic systems and sewage treatment facilities to reduce discharge of nutrients to surface water and groundwater

Careful industrial practices such as limiting the discharge of nutrients, organic matter, and chemicals from manufacturing facilities.

Funding efforts to restore wetlands along the coast to naturally filter the water before it enters the ocean.

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These solutions are relatively simple to implement and would significantly reduce the input of nitrogen and phosphorus.

A similar approach has been used successfully in the Great Lakes recovery from eutrophication.

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HABHRCAHarmful Algal Bloom and

Hypoxia Research and Control Act

In December 2004,

US Congress recognized the severity of these threats

Reauthorized the Harmful Algal Bloom and Hypoxia Research and Control Act of 1998 (HABHRCA 1998) with the Harmful Algal Bloom and Hypoxia Amendments Act of 2004

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Scientific understanding and ability to detect, monitor, assess, and predict HAB and hypoxia events.

It authorized funding for existing and new competitive research programs on HABs and hypoxia, including a new program to research methods of prevention, control, and mitigation of HABs.

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Major report findings are given below

Harmful Algal Bloom Management and Response Assessment and Plan, 2008

Scientific Assessment of Marine Harmful Algal Blooms, 2008

Scientific Assessment of Hypoxia in U.S. Coastal Waters, 2010

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Conclusion

Marine dead zone is low oxygen area called hypoxic region

Ocean dead zones were occurred till 1960’s

There are about 400 MDZ’s in the world This is continuous process Hypoxia can form by both natural &

human induced factors In fall hypoxic regions can disrupt &

create in the spring & summer. There are impacts for Environmental,

Social & Economic areas. There are such plans for avoid MDZ’s

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Acknowledgement My heartiest thanks goes to

Dr.RRMKP Ranatunga for his vital encouragement.

Persons in Zoology & main library in University of Sri Jayawardenepura.

Mrs.Sunethra Kariyawasam in NARA.

For all are who helped me

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References

Web sites

Goddard Earth Sciences, Data and Information Services Center, NASA

Bleachpedia NOAA

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Marine dead zones

Education

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