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Ocean Interactions
Ocean and Atmosphere connecting Scientists, Teachers & Students
Questions (week 2: 10/27/03)
Chartiers-Houston Jr./Sr. High School, Houston, PA
Class profile (to come)
Teacher: Mr. Pop
Thanks very much to Mr. Pop's Jr High students for the insightful questions. If I'm not mistaken, Houston PA is south of and not too far from Pittsburgh. I grew up about 30 miles away, in St. Clairsville Ohio!
1) The Ron Brown typically does not do alot of research on coral reefs. Reefs are typically in 'shallow' water, and the "Ron Brown" is a 'deep' water vessel. To conduct research on coral reefs, one typically uses a smaller ship. Also, the types of research that we are doing are most effective away from the coasts of landmasses. River effluent, shallow water, tides, currents, and air pollution all contribute to generally clouding the atmospheric and oceanographic data sets. Our measurements are very precise, and these other influences work to confuse the interpretation of our data. Also, since so much of the Earth (as is easily seen by looking at the globe in your classroom) is covered by deep water and so much of the ocean surface is far from any coastline, there is alot of work to be done in deep oceans.
So, no one on this particular vessel is studying reefs. However! Many of the crew members are NOAA-certified SCUBA divers (This program is very rigorous, and is probably only second to the Navy dive school in terms of prestige). Often, the Brown makes port in places where there are excellent chances to dive coral reef recreationally (for example, the Maldives Islands, Kwajalein, Australia, the Caribbean). Jeff has also participated in some of these reef dives. However, we won't be near any coral reefs during this expedition.
As you are probably aware, coral reefs are a vital part of the oceanic ecosystem, and they are some of the most biodiverse places on the Earth. I have read studies which show that the health (or lack of health) of our world's coral reefs is an indicator of the health of our Earth System. Furthermore, coral reefs are very sensitive to climate changes, and the unique plant and animal life found there are irreplaceable.
It is my understanding that the loss of biodiversity on the coral reefs is due to compounding factors: pollution from our streams and rivers, overfishing, and possibly due to climate change. Coral reefs form where the water is relatively warm (around the equator, for example) and plenty of sunlight. In healthy coral systems, a symbiotic relationship exists between the coral, plankton, algae, and fish. Small disturbances to this delicate balance can cause the ecosystem to die.
For example, sewage or agricultural runoff can cause nitrates and phosphates to overfertilize the water, which leads to algal blooms (too much algae). Furthermore, the bloom may obscure the much-needed sunlight. Also, bacteria from the runoff may consume all the oxygen in the water which is needed by the ecosystem.
With deforestation of tropical forests and drying up of coastal wetlands due to overpopulation and development, some of the natural sediment and nutrient filtering mechanisms are reduced, and this can push the reef ecosystem out of balance. Corals respond to excess silt by secreting mucous to coat their delicate exterior. This secretion stresses and weakens the coral, making them vulnerable to infection from bacteria in the agricultural runoff. Furthermore, many people live near the coasts, and these people need to eat fish and need to have jobs in order to maintain a standard of living. Unfortunately, some of these people have taken to gathering fish from the coral reef to sell to fish suppliers. The fish are then sold to you and me to put into our aquarium at home. This isn't so bad (they don't necessarily take all of the small fish)....except for the fact that some of these coastal fishermen have chosen to injecting poison into the reef to stun the fish. Then, they scoop up the fish with nets, but the coral dies from the poison. Another technique that destroys the reef is to stun the fish with explosives (this breaks the delicate coral apart).
Scientists have also noticed that when El Nino warms the coastal water, the symbiotic algae withdraw from the coral. The coral then becomes bleached and dies. Another problem is overgrazing by infestation of crown-of-thorns starfish. Ordinarily, there are a few crown-of-thorns which eat the live coral, but when sewage and agricultural runoff get too heavy, the plankton over-produce which causes a dramatic increase in crown-of-thorn population.
I will admit to you that I am not an aquatic biologist...I'm a meteorologist who happens to also have an abiding interest in SCUBA diving and so am interested in healthy coral reefs. I get most of my information about coral ecosystems from National Geographic magazine!
2) As Mr. Pop's students know, El Nino doesn't happen every year. In fact, the cycle of El Nino is fairly irregular, but it occurs every 4-8 years or so. The cycle starts roughly in the Spring and ends roughly the following Summer, so the total length of an El Nino is about one year to 1.5 years. Each El Nino is different...some last longer, some are more intense.
I'll remind you how El Nino works. Normally, due to the way that the currents run along the west coast of North and South America, there is upwelling of cold water from the deep near the coastline. The colder water is blown west by the trade winds, it is warmed by the sun as it travels, and it arrives in a 'warm pool' region of the Earth in the western Pacific. This warm water heats the air above it, causing convection, clouds, and rain.
El Nino happens because during some years, the easterly trade winds slacken, and the warmer water that would normally be moving to the west is shifted to the east (it doesn't make it all the way across the Pacific). This causes the center of the heavy precipitating region to be shifted to the central Pacific.
Part of our studies out here in the eastern Pacific are tied to El Nino. The TAO buoys, which straddle the Equator across the Pacific, have helped to improve our ability to predict El Nino, since the buoys constantly monitor the temperature of the water. When modellers try to predict El Nino, they can compare their results to what the buoys have measured during past El Nino events to see if they can accurately reproduce those data.
By being here (currently at about 9N, 95W), we cannot tell whether or not El Nino will come next year. El Nino is a very large scale phenomena (across the entire Pacific Ocean), and our ship is only one little spot in the big ocean. However, I recall that we recently had a mild/moderate El Nino, so my GUESS is that we won't have one this year. Maybe you students can tell US if we will have an El Nino. Check out www.elnino.noaa.gov, and that website may help provide you with some more information.
3) As you can see from the map, the trackline of the "Ron Brown" goes from Pensacola Florida, south through the Panama Canal, and out to a series of TAO buoys in the Pacific (which is where we are now). Once we have completed our work on the buoy lines, we will be heading back toward Panama. We will have a few days in Panama City, then we will head back through the canal and head North again on the Atlantic side. We will pass between Cuba and the Yucatan, around the bottom of Florida, then head up along the East Coast of the U.S. Our final destination is Charleston, South Carolina, which is the Ron Brown's home port. The only places where we will touch land on this trip are: Pensacola FL, Panama, and Charleston SC. It would be fun to go to more places, but it is expensive for the ship to tie up in foreign ports. The ship can only travel about 12 miles per hour, so it isn't easy to zip over to an interesting place just for a visit. We have a job to do and a schedule to keep.
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