Spotlight on Zoo Science
April 18, 2006
Health Care for Marine Ecosystems
A National Zoo scientist and veterinarian is working to promote ecosystem health off the coast of western Africa.
The 6.5 billion humans alive today are creating an unprecedented amount of stress on our planet. Landscape modifications, natural resource consumption, pollution, and global trade and travel, are all taking a toll. The impact of this stress can be seen in our cities as well as in some of the most remote areas of the planet. For example, health problems due to pollution are increasing in many urban centers in the United States, and even in the Arctic, wildlife and people have high levels of mercury in their tissues.
The 1999 entrance of the West Nile Virus into North America serves as an excellent example of what can happen at the intersection of animal, human, and environmental health. After its entrance into North America, West Nile Virus led to human deaths, increased pesticide use to combat the mosquitoes that carry the disease, and possible ecological disruption because so many birds died.
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The majority of the human population lives in coastal areas, threatening marine ecosystems. |
Around the globe, coastal ecosystems are particularly stressed. More than 60 percent of the human population lives in coastal areas, and coastal populations are increasing at twice the rate of inland ones. For millennia, people have used oceans as sinks for waste, and have harvested seafood from them with little or no regulation on the take. Now, it is becoming more and more evident that polluting and exploiting the oceans is affecting human health, the health of marine wildlife, and the health of our planet—most of which is covered by oceans.
Gulf of Guinea: The Marine Ecosystem
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I currently live in Gabon, working for the Smithsonian’s National Zoo to evaluate marine ecosystem health in the Gulf of Guinea, an arm of the Atlantic Ocean off the west coast of Africa.
This region is rich in marine wildlife—humpback whales breed here, leatherback turtles nest here, and Arctic terns can be found here during their migration, which is the longest of any bird species. However, threats to this diverse ecosystem are great, and the implication for planetary stress is enormous as this area becomes more important for supplying the world’s growing demand for oil, protein, and timber.
Threats to Marine Ecosystem Health in Central Africa
The Gulf of Guinea contains rich oil reserves, plentiful seafood stocks, and vast stands of timber trees. These three resources are in high demand around the world and their extraction and sale provide much-needed economic support to the people of Gabon.
How the ever-increasing extraction of these resources will affect Gabon’s environment is unknown, but it could have an overwhelmingly negative impact if resource extraction is not carefully managed to ensure that it doesn’t damage the long-term health of the environment. However, there are already signs of damage to coastal ecosystems.
For example, industrial trawling for fish in this area has greatly increased recently, and much of it is conducted in illegal zones. Overfishing is of great concern and none of these trawlers is required to use turtle excluder devices (TEDs) to prevent sea turtles from becoming entangled in the trawlers immense nets.
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Leatherback turtles may be caught in the huge nets of trawlers fishing off the coast of Gabon. |
As a result, in the past few years dead sea turtles and other marine life have washed ashore in what appear to be record numbers—although monitoring of these events has been sporadic so the true change in these numbers is hard to quantify. In addition, local fishermen report less abundant catches.
With less fish locally available to supply their protein needs, people are going into Gabon’s inland forests to find meat. And often this meat is “bushmeat” from wild animal species including many endangered primates. In this case, at least, stress on the coastal ecosystem is leading to stress on the region’s terrestrial biodiversity.
Off-shore oil extraction is another threat. Even the most careful methods of oil extraction result in some amount of leakage and contamination of water, which makes careful monitoring critical to the marine wildlife that share the seas with these operations. Actual oil spills, of course, have devastating effects on wildlife, and there are many reports of local spills in Central Africa.
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| Humpback whales in the Gulf of Guinea may be disturbed by seismic testing for oil. |
In addition, to locate potential well sites the oil industry uses seismic testing, in which a picture of sub-surface geology is acquired by reflecting sound waves from geological features. This can have a negative effect on marine mammals that use sonar to navigate and communicate. Three common marine species in this area—the humpback whale, manatee, and leatherback turtle—are at high risk from this activity and yet, to date, we have no data on the effect of seismic activity on these animals.
Inland logging also affects coastal ecosystems. In order to transport timber out of the African forests, logging companies load up boats with logs and transport them along Africa’s rivers. In transit, many logs drop off boats and into the rivers where they are sometimes carried out to sea and then wash up and lodge on the beaches. Leatherback and other turtle species become trapped by these logs while nesting—females become exhausted and disoriented trying to get around the log barriers, and die.
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Logs littering the beach entrap female sea turtles. |
Garbage—marine debris—is also most likely a danger to marine mammals in the area. Debris is often consumed by the animals, which mistake it for prey, and animals become entangled in the debris as well. Eating debris may lead to gastrointestinal blockage and death, while entanglement may result in decreased foraging capabilities or even death by drowning. Marine debris is a source of wildlife destruction in many other parts of the world.
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Some aquatic animals mistake garbage for food— and may die as a result. |
Health Care for the Marine Ecosystem
The first step in providing health care to the Gulf of Guinea’s marine environment is to determine its health status. The sickness or health of an ecosystem can be determined by the long-term monitoring of several factors: a change in mortality rates of key species in the area; the frequency of pollution events; the occurrence of both emerging and endemic diseases; and a change in species abundance and diversity. For these data to be useful however, it is important to have a baseline assessment of the current situation.
My job in Gabon with the Smithsonian’s National Zoo is to develop health assessment programs that will document baseline health parameters for wild marine mammals. With these, we can better gauge the degree of sickness or health of the Central African marine ecosystem.
I am collecting biomaterials from live animals of several species to establish normal data for a variety of physical parameters, including blood chemistry, toxin levels, and exposure to infectious and parasitic agents that cause disease. In addition, I perform necropsies (a necropsy is the animal equivalent of an autopsy) on stranded animals to collect invaluable data on the health status of the species they represent and help to elucidate causes of mortality.
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Sharon Deem collecting a blood sample from a sea turtle. |
Working alongside scientists from different agencies around the world, we can monitor wildlife, and begin to see how Central Africa is responding to the increased human footprint on the Gulf of Guinea. We will be able to determine whether this marine ecosystem is healthy or sick. And with these data in hand, we can then implement management practices, such as preventive medicine programs, necessary to maintain its health or apply treatments to overcome sickness.
In the months I’ve been in Gabon, I have already seen ways we can apply health care to minimize the potential impact of industry on the coastal ecosystem. These include:
- implementing measures to remove logs from sea turtles' nesting beaches,
- minimizing by-catch from trawling operations by encouraging the use of such devices as TEDs and by enforcing laws and regulations to keep trawling out of illegal zones,
- establishing rapid response protocols to deal with the inevitable oil spill,
- educating people on the effects of marine debris and instilling a concern for the marine environment that will inspire people to want proper garbage disposal, and
- working with others to minimize the negative impact of fisheries, while continuing to feed the people of the region and ensure seafood can be a source of income for people in the region.
People living outside of Central Africa can help by learning more about marine ecosystems around the world and by finding ways to minimize their impact in their own marine areas. If you live in the Washington, D.C., area, read about continued threats to the Chesapeake Bay and learn what can be done to save it. Pollution from Washington, D.C., flows into the Chesapeake, which flows into the Atlantic Ocean—and the Atlantic you see from Ocean City is the same one I see from my field site in Gabon.
Our growing human population, and especially our use and abuse of natural resources, is causing harmful global change. Preventive measures must be implemented now to mitigate the long-term impact of this change. The marine ecosystem health program in the Gulf of Guinea is one example of how the Smithsonian’s National Zoo is working to protect the health of our planet and the animals and people who live here.
—Sharon Deem
If you are interested in learning more about Sharon Deem’s work, please feel free to contact her at
Email
. If you are interested in contributing to the marine ecosystem health program in the Gulf of Guinea, thank you, and please contact Patti Young at
Email
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Note to Media: If you would like more information about this project, or any of the Zoo's conservation and science programs, please contact the Zoo's Office of Public Affairs.
