"Teaching people about the world in which we live."
"Teaching people about the world in which we live."
The researchers on board the Undersea Explorer answered our questions and
we provided this information to you in the form of daily logs of our 6 day dive trip.
Then Andy Dunstun, a marine biologist, answered questions for our readers in a live
interview. The log of that interview is still available
for you to view.
The first week in May, 1998 was our scheduled SCUBA diving trip to the Great Barrier Reef. This reef is the longest uninterrupted reef in the world and at Osprey Reef, one of our dive sites, the vertical walls stretch over half a mile deep into the ocean. Of course, we didn't dive that deep because we are sports divers and we are breathing compressed air. Both these factors limit our dives to not much more than 100 feet.
The primary
purpose of this week long diving expedition was to gather information about the ocean ecology and some of the specific species in this part of the
ocean. On board the ship we had the help of a marine biologist
who taught us how to get accurate data and then how to interpret it. The species we
studied ranged from the tiny plankton to some seriously large sharks! Without a healthy plankton population, the largest of the
sharks would be in serious trouble because the plankton form the very basis of the sharks
food chain. Another ocean dweller which depends upon a healthy supply of plankton is a
shell fish called the chambered nautilus. The nautilus has a
beautifully curved shell which continues to grow in sections, or chambers, as the nautilus
animal itself grows. Mathematicians have examined the shape of the nautilus shell and
plotted several interesting equations showing how the growth of the shell maintains some
very pleasing proportions for each chamber.
One fish
species we saw on the reef dives was a shark. There are many species of sharks, ranging
from the small dwarf shark to the huge whale sharks. The best known and the most ferocious
is the Great White Shark; however, we didn't see any of
these predators because they live in the colder waters of Southern Australia, not the
tropical waters of the Great Barrier Reef off Queensland, Australia. We thought that the
most exciting part of our scientific explorations would be the shark tagging we would
watch. However, we also found it every bit as exciting to watch the chambered
nautilus' being captured, measured, marked and released.
Sharks are tagged so that scientists can track the movement of individual sharks. These movements provide the biologists with information, not only about those specific sharks, but also about the movements of whole populations. These facts then help the ecologists to understand changes in the entire ecosystems which form the Great Barrier Reef, home of one of the world’s most diverse aquatic ecosystems.
The air we breathe at the surface of the ocean (at sea level) is at a pressure level called one atmosphere. Above sea level, air pressure decreases and the air is called rarefied. Below the surface of the ocean, the weight of the water creates additional pressure. This means that air pressure inside an air-filled object must be increased to maintain the shade and size of the object. When a SCUBA diver is below the water’s surface, his or her lungs must be filled with greater pressure levels to prevent the water’s squashing the diver’s chest. (This is actually true of many air-filled areas of the diver’s body, but the lungs will serve to illustrate this phenomenon.) The SCUBA air regulator serves the purpose of providing the diver with higher pressure air (called compressed air) to prevent this unequal pressure on the diver’s chest. Thus the real secret of SCUBA is that it provides air at the right pressure to a diver swimming at various depths beneath the ocean. One of the limiting factors of breathing compressed air is that at pressures necessary when divers are more than 100 feet down, the nitrogen in the air begins to make diver’s feel giddy or drunk. This effect is called nitrogen narcosis or "raptures of the deep." Drunken behavior is dangerous enough on the surface; at depth it can be fatal to the narcotic divers or to their companions. Therefore, sports divers do not diver much deeper than 100 feet. The author is this page, Dr. Leslie Whitaker, has conducted and published research testing the impact of narcosis on thought and behavior (Whitaker, L., & Findley, M. (1977). Nitrogen narcosis measured by dual-task performance. Journal of Applied Psychology, 43, 71-84.)
Ecology is the
study of living systems of plants and animals and the environment in which they live. On
the Great Barrier Reef, we will be examining the relationships among the flora (plants),
fauna (animals), and their environment (the reef and the ocean waters). One of the basic
assumptions of ecology is that no part of a living system changes without having an impact
or the remainder of the system. A coral reef is a particularly rich place to study ecology
because of the diversity of plants and animals there. The coral itself (a living
combination of a plant and an animal) is particularly sensitive to changes in the
ecosystem, and so it is a good place to look for the impact of change. Ecology is the
study of interrelationships. Ocean Ecology studies these interrelationships in ocean and
seashore systems.
The Great Barrier Reef is a stretch of shallow tropical water lying off the Pacific coast of Queensland, Australia. It is the longest coral reef in the world and stretches 1240 miles (2000 kilometers) in a roughly north-south line of water rarely more than 100 feet (30 meters) deep. In places, the reef is a 100 mile (160 kilometer) wide area of islands, atolls, and coral reefs which serve as a baffle through which warm tropical water moves. The reef truly serves as a barrier which protects the interior reef ecosystems and the Queensland shore from winter storms. It is home of 1500 species of tropical fish and 400 finds of hard and soft coral. In 1770, this reef almost spelled the end of Capt. James Cook’s exploration of the Australian coast. Their ship, the Endeavour, managed to sail in through a gap in the reef at Whitsunday passage, but then almost wreaked when they attempted to find a way back out through the dense coral shoals.
Plankton, the wanderers of the world’s waters, consist primarily of one celled plants and animals. However, some of these plankton are really the immature or larval forms of larger animals, like shrimp, starfish, fish, lobsters, and crabs. Some scientists classify a jelly fish is a plankton all its life, even when it grows to be several feet in diameter, because its primary means of locomotion is to drift with the ocean currents. This "wandering" or drifting means of locomotion is an essential characteristic defining plankton. Because plankton are so plentiful and are spread so widely around the world (in both salt and fresh waters), they form the basis of the aquatic food chain. That means that whatever affects the krill (a plankton) will affect all the animals in a food chain. A food chain may be short; for example baleen whales feed directly on krill (a plankton.) Other food chains may be long; for example humans eat tuna. The tuna then eat squid who eat anchovies who eat crustaceans who eat plankton (diatoms), all depend on the healthy population of plankton. A bloom of plankton occurs when nutrients and temperature are ideal for rapid multiplication of a plankton population. The water may turn a red or yellow color as the plankton bloom. This is too much of a good thing because the bloom can suffocate fishes, shellfish, and other animals when the plankton clogs their gills. After the bloom, the dying plankton (flagellates) can poison the water. Blooms may occur when industrial or agricultural pollution adds too many nutrients to the water and the plankton multiply rapidly.
Self-Contained
Underwater Breathing Apparatus. SCUBA is a form of equipment that allows a person
to breathe underwater from a supply of air that is carried with them. There are many
forms of Scuba training available. Lara Steele is a PADI Open Water Instructor and
Shawn Steele is a PADI Dive Master. They have both enjoyed diving for many years.
When taught by competent instructors Scuba diving is a very safe sport. It is
enjoyable and educational. The freedom of floating in water combined with the
ability to breathe is incredible. There really are not very many things so inspiring
as Scuba diving. Most certification programs accept students in good health as young
as the age of twelve.
The aqualung or self-contained underwater breathing apparatus (SCUBA) was originally developed during World War II for military purposes. However, since that time millions of water-loving sportsmen and women have been able to use this invention to explore the underwater world strictly for pleasure. SCUBA allows divers to stay underwater for periods of one to two hours, breathing air and swimming among aquatic plants with fish and other marine animals. Although these sports divers are trained in special courses, their training does not allow them to safely dive to the maximum depths possible with this equipment. Instead they explore the first 100 feet or so of the underwater world. This is actually the most interesting area for the sports diver because sunlight penetrates approximately 100 ft. (30 meters) with enough strength to allow the growth of underwater plants and the rich animal life such plants support. Below this depth, the coral usually does not grow and the rich colors found nearer the surface fade and dim.
