exit choose to view chapter section with a click on the section heading. ►global habitat...
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►Global Habitat Destruction
►Sensitive Marine Habitat Destruction
►Pollutants and Their Effects
►Toxic Pollutants
►Nutrient Pollutants
►Energy Pollutants
►Refuse Pollutants
►Efforts and Solutions
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Global Warming
Greenhouse gases include water vapor, carbon dioxide, methane, and CFCs.
Data supporting the Earth’s averagetemperature is on the rise is: Carbon dioxide in the atmosphere is rising. Burning of fossil fuels has released carbon,
in the form of carbon dioxide. This carbonwas isolated from the carbon cycle untilhumans started burning it.
The oceans currently absorb from 30%to 50% of carbon dioxide emissions.
There is an overall rise in sea level. More ofthe ice held in the polar ice sheets melts astemperature rises. Sea level may rise asmuch as 0.3-1.5 meters (1-5 feet).
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Global Warming (continued)
Possible effects of global warming include: A rise in average temperature about 2°C
in the next 50-100 years. Habitat destruction due to climate changes
and an increase in violent storms. Flooding of coastal areas due to a rising
sea level. A rising sea level may slow and/or alter
oceanic currents with resultant widespreadecosystem damage.
The Kyoto Climate Change Conferenceagreed that by 2012 industrial nationswould need to reduce carbon dioxideemissions 6%-8% below 1990 levels.
The only real solution is to find and developcost-effective alternatives to fossil fuels.
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Damage to the Ozone Layer
The Ozone layer protects us from ultraviolet radiation. Without it, life in it’s current form could not exist.
Ultraviolet radiation (UV) damages DNA and protein. It is associated with mutations, cancer and reduction in reproduction. It can cause cataracts and suppress the immune system.
Decreased protection from UV would have a negative affect on crop yields, planktongrowth, and world productivity in general.
In June 1990, 53 nations agreed on an international ban of ozone-depleting chemicals. The ban took effect in 2000, so it will be some time before we know how it will affect the ozone layer. The significance of the ban was that it demonstrated the international community can cooperate to solve global issues threatening us all.
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Non-Native Species
Ships can carry non-native species to new environments. They take on and release ballast water to maintain stability. Water picked up in one
area could be released in another, half the world away. The new species may die due to water, climate, or starvation. The new species may have characteristics that allow
it to out compete local organisms becoming abiological invader that can shift the ecological balance,sometimes even destroying an ecosystem.
Species transplantation is so rapid and countermeasures have been so ineffective that many ecologists think the world will soon be a one-world homogeneous ecosystem. These introduced species could wipe out existing
competitive species. This could result in a significant reduction in
biodiversity on a worldwide level.
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Overfishing
Overfishing not only harms specific fisheries, but also the overall health ofthe environment. Overfishing affects local ecosystems by creating an imbalance. You can’t eliminate species from an environment without disrupting its
ecological balance.
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Coastal Wetland Destruction
The primary cause of coastal wetland destruction is people and their desire to live near the coast.
Estuaries are particularly at risk of destruction for several reasons: First, they’re not only potential real estate by being filled in, but they’re also potential
harbors by being dredged out. Second, estuaries are very sensitive environments. It only takes one part per 10
million of oil in water to seriously disrupt growth and reproduction of some species in this type of wetland. Migrating birds stop over in estuaries – they can carry the pollution thousands of kilometers away.
Third, because of their proximity to urban centers, US estuaries are among the most polluted on Earth.
Mangroves forests are a good worldwide example of what can happenvery quickly. Today more than 50% of the world’s mangroves have been destroyed and are
continuing to vanish – even faster than tropical rainforests.
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Coral Reef Destruction
Human activities are destroying one of the world’s mostproductive ecosystems, the coral reefs.
Much of the destruction has to do with coral bleaching whichoccurs when coral polyps reject the zooxanthellaedinoflagellates living in them.
Bleaching seems to correlate with high surface temperatures,which in turn appear associated with ENSO events. Research also suggests that agricultural runoff triggers coral bleaching.
Besides bleaching, a host of other ailments attack coral: Disease nearly wiped out the Caribbean black spiny sea urchin that eats the algae that, in turn,
compete with and displace coral. Global warming is raising temperatures above coral’s survival range. Nutrient rich run off encourages
competitive algae to grow. Killing fish for food with dynamite causes widespread death and damage to coral. Tropical fish collection by using cyanide is killing coral as well as fish.
25% has been destroyed and estimates are that in 50 years there will no longer be any coral reefs alive.
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Definition of Pollution
A definition of pollution. With respect to the marine environment, it is useful to define pollution as substances or energy that can change the water quality or affects the physical, chemical, or biological environment.
Sources of Pollution Sources of marine pollution are a cocktail of
hundreds of substances contributed fromcommon everyday activity, like driving cars,what we throw away in landfills, and run-offfrom farms and parking lots.
One third of the pollutants entering the seacome from the atmosphere, depositedby rainfall.
Each year we dump about 100 million tonsof plastic, 17 million tons of sewage andsludge, 5 million tons of oil, and 5 trillion gallonsof toxic waste into the marine environment.
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Heavy Metals
Even small quantities of heavy metals are a major threat to organisms. Heavy metals of most concern are lead, mercury, cadmium, arsenic,
and copper. They damage organisms by interfering with cellular metabolism and are not easily
eliminated, so they tend to collect in organisms’ tissues over time. Bioaccumulation is the concentration of heavy metals, synthetic organic chemicals,
and natural organic chemicals in an organism throughout its lifetime. Biomagnification is what happens when the concentration of heavy metals or other
substances rises as it moves up the food web – concentrates as each level of the food chain consumes the one below.
There is a significant risk to humans. Mercury, which has been associated with birth defects and an increase in brain damage and behavior disorders over the past 20 years, appears to be linked to heavy-metal poisoning. Fish that accumulate the highest levels of heavy metals are tuna, swordfish, mackerel,
and shark. Other heavy metals to watch out for are lead (from paint), copper and tributyl tin (TBT
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Synthetic Organic Chemicals
Known as synthetic organic chemicals because they are human-made but are based on an organic molecule structure.
These are dangerous because they can be toxic in small quantities, persisting in the environment because bacteria and other processes don’t break them down.
Normally they exist in very low concentrations, but organisms can bioaccumulate them just as they do heavy metals.
Many synthetic organic chemicals alsobiomagnify. They cause harm at any trophic level, but they are the greatestrisk to top-level predators, including humans. Substances that biomagnify
are called conservative materials. They’recalled this because they’re conserved ratherthan consumed as they move throughthe food web.
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Oil
Major sources of oil pollution in the ocean are: Annually about 6 million tons of petroleum hydrocarbons reach
the sea. The major cause is the users, not the producers.Oil enters aquatic environments through runoff from parkinglots and streets and as waste from sewage treatment plants.
Automobiles are another major oil source. Incompletecombustion releases waste petroleum hydrocarbons into the air.
Petroleum reserves naturally seep into ocean, adding aboutas much as atmospheric fallout.
Oil pollution can affect marine species with behavioralchanges ranging from anesthesia to aggression. Aquaculture is at risk because the fish can’t flee from
an oil spill. Among natural fisheries the eggs and larvae are at risk. The food source most affected by oil is shellfish.
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Oil (continued)
Refined oil is more hazardous. It disrupts the environment more extensively and for longer periods than crude. This is because refinement breaks up the heavy crude oil components and
concentrates the lighter, biologically active ones. Refined oils have added chemicals that make them more toxic.
Cleaning up an oil spill. Although it is helpful to use some clean-up
measures, other chemicals and methodscause more damage than the oil spill itself.
Using the damage caused by the cleanup ofthe Exxon Valdez oil spill in 1989, scientistsnow conclude that often the best thing(politically the hardest) to do is to leave an oil spill alone.
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Radioactive Waste
Radioactive materials get into the oceans by people dumping it there. Today radioactive substances come primarily from nuclear-reactor cooling water and
nuclear-power vessel discharges.
Dumping has been banned since 1975 butradioactive waste is still a concern. The amount already dumped
into the sea previously by the US andmore currently by Russia is a threat tolocal marine resources.
Despite the obvious danger radiation posesto living organisms, so far no widespreadeffects have been noted. It appears thatmarine organisms have a high toleranceto radioactivity. It is just a matter of time though before measurable effects become evident – probably genetic damage.
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Munitions
The concerns for the environment regardinglost munitions range from minor up: The detonation of unexploded bombs is more
of a safety concern for ships and divers thanit is a long-term, wide-rangingenvironmental hazard.
Leakage of chemical weapons, on the otherhand, could pose a major threat bycontaminating and killing local wildlife.
Even though banned, some countriesare probably still coastal dumping.
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Eutrophication
Excessive nutrients that throw the local ecosystem out of balance is called eutrophication.
Eutrophication can hurt ecosystems: Can create dead zones on the bottom. Areas that
have low oxygen (hypoxic) and no oxygen (anoxic). Low-oxygen either kills fish, shrimp, etc. or
causes those that can to flee. This can ruinlocal fisheries.
Some nontoxic algae blooms can cause lethalconditions in surface waters. These can clog thegills of some species and consume all thefree oxygen.
Red tides and similar algae blooms are calledHABs – Harmful Algae Blooms.
Today, anoxic and hypoxic events cause moremassive fish kills than any other single causeincluding oil spills.
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Sewage
There are three process levels used to treat sewage before dumping. Level I removes solids. Level II removal of solids and pathogens (disease-causing microbes). Level III removes solids, pathogens, and nutrients.
After treatment the isolated solids make up sewage sludge. A mixture of organic materials as well as bacteria, viruses, metals, and synthetic chemicals. Sludge is then used for landfills, burning to generate electricity, or dumped at sea.
Dumping can cause several concerns: 1. A sea bottom covered with sludge results in a hypoxic
environment in which few organisms can survive. 2. Storms can dislodge sludge washing it onto local beaches,
contaminating shellfish beds, and causing disease outbreaks. 3. New York is dumping sludge on the continental shelf and
scientists worry it could contaminate the Gulf Stream. Livestock produces more waste than a comparable human population and it isn’t
generally processed like human sewage. Instead it seeps into ground water and storms can wash out storage ponds.N
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Heat Pollution
Heated water is a pollutant because hot water can raise temperatures above the tolerance level for many species, causing a die-off or decline in the immediate areas where the warm-to-hot water is.
Most thermal pollution comes from power plants, which draw water from the sea for cooling. By using heat exchangers the discharged hot water remains free of radiation and contamination. Usually the heat is the only pollutant. Some industrial discharges do pollute with both heat and substances.
Sound Pollution A rising concern is sound pollution.
Human-produced sounds ranging from ship engines to sonar may be detrimental to marine species.
Concerns include noise interfering with whale communications and high-intensity soundinjuring marine organisms.
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Plastic
Plastics get into the marine environment primarily by being lost or dumped there. Including fishing gear, bags, packing materials, balloons,
bottles and syringes.
Plastics are a hazard in the marine environment because they look like food to some predators. Sea turtles and sea birds commonly die when they swallow
plastic bags and similar items that resemble jellyfish, their natural prey.
Larger marine animals can swallow small pieces as food. Once swallowed, the plastic can cause internal blockage and a swift death. Or, it can accumulate in the gut, inhibiting feeding, resulting in slow starvation.
Plastics are a hazard through entanglement and entrapment. Biodegradable plastic in the marine environment is one answer. Recycling – the best solution is to keep plastic out of the ocean altogether.R
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Dredge Spoil and Industrial Solids
A major pollution source is spoil. Spoil is the soft bottom material removed during the dredging of harbors and ports. More often than not this isdumped at sea.
The bottom of harbors tend to contain toxic chemicals from shipping and development. These chemicals damage the benthic communities when dumped with the spoil at sea and does damage even without toxins.
Benthic organisms die when buried in the spoil. Suspended particles carried from spoil cloud the water and clog the feeding and respiratory organsof organisms.
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The Cost of Pollution
Pollution is ugly, offensive, and destructive. If that weren’t enough,it’s expensive. The US spends about $250
billion annually to control atmospheric, terrestrial, and marine pollution.
That equals about 2% of thegross national product, about $1,000 for each US citizen.
Additional estimates suggestthe US loses about 4% of itsgross national product toenvironmental damage.
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Managing the Coastal Zone
The Coastal Zone Management Act(CZMA) of 1972 provides economicincentives for states to take a strongrole in preserving their coastal zone.
This act helps to counterbalance theeconomic pressures that lead to coastalzone destruction and helps make coastalresource management more consistentfrom state to state.
The Marine Protection Research andSanctuaries Act of 1972 gives the federal government the power to designate specific coastal zone areas for research, protection, or recreation.
Perhaps the most significant result of these acts has been the establishment of multiple marine sanctuaries on both coasts where the environment is provided a safe, natural refuge and where scientists can study the marine environment in a more natural or protected state.
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International Conservation Efforts
1972 – Ocean Dumping Convention resulted in an international agreement that prohibited marine dumping of persistent (nonbiodegradable) plastic.
1973 – Marine Pollution Convention (London International Convention for the Prevention of Pollution from Ships) established regulations that limit and control oil pollution, packaged substances, sewage, and garbage dumped from ships.
1973 – International Convention for the Prevention of Pollution (MARPOL) took place. It regulates discharge from ships and has been adopted by more than 80 countries.
1980 – UN Environment Program, the International Union for the Conservation of Nature and Natural Resources, and the World Wildlife Fund released the World Conservation Strategy. It provides a strategy and procedures by which nations can develop their economic potential without destroying their resources.
It recommends that countries with common seas work together to find common solutions to shared marine problems. This led to the Regional Seas Programmes, which have establish zones for international cooperation around the world.
1991 – Madrid Protocol on Environmental Protection of the Antarctic Treaty banned mining and oil exploration in Antarctica for at least 50 years. It further designated the entire continent as a natural reserve devoted to peace and science.
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