Mission 8 By: Poseidon's Narwhals 1

THE YANGTZE RIVER The Yangtze River is one of the longest rivers in the world. It used to be an extremely clean and clear river. But these days, the Yangtze River is the 4th largest sediment carrier in the world, because the country is such an industrial country. Some highly endangered species that live in the Yangtze River are the Yangtze sturgeon(Acipenser dabryanus), Chinese sturgeon (A. sinensis), and the Chinese swordfish (Psephurus gladius). The largest lizard in the world, Audrias davidianus, Red-crowned crane (Grus japonensis), and the extremely endangered Yangtze alligator (Alligator sinensis). The Yangtze River Baji dolphin used to reside in the Yangtze River but has gone extinct. The Yangtze River is extremely polluted and is no longer safe to drink from. 2

HOW ORGANISMS LIVE IN THE ECOSYSTEM AND HOW THEY INTERACT Consumers: Decomposers take food and energy processed by consumers. We are consumers. Consumers can be plant eaters (herbivores) or meat eaters (carnivores). Consumers normally eat whatever is available in their food supplies. The health of any ecosystem is dependent upon the balance of what make to make enough food for consumption by the consumers which in turn most not deplete resources. Consumers break down their metabolism and use the food for consumption supplied by the producers. Decomposers: A decomposer is an organism that breaks down dead plant and animal matter. This may sound disgusting to some people but the fact is our ecosystem could not function without living decomposers. This is because like we need recycling in our community the animals need to have their own recycling proccess also. That is decomposers. Decomposers eat dead bodies and stuff so that it does not pollute the animals habitat. Thats why we need decomposers. So when they say I have to describe the organisms that live in the ecosystem and how they interact this is how I do it. I broke it into three different categories decomposers, producers, consumers. 3

HOW TO DETERMINE THE HEALTH OF AN AQUATIC SYSTEM One way of determine the health of an aquatic system is to take a look at the rivers color or density to see what kind of shape the river is in. You can also test what kind of animals are in the river if there are a lot of non-pollutant tolerant macroinvertebrate, that indicates that the water is very healthy. 4

BIOINDICATORS AND CHEMICAL PARAMETERS The Yangtze River is definitely not healthy because it is the first vertebrae that has gone extinct for 50 years due to human activities. In 1999 scientists surveyed the river and there was only 13 Baji dolphins. So in a span of only 49 years the Yangtze River has gone from being a habitat to thousands of Bajis to only 13 Bajis. The Yangtze River has many chemical parameters because 33.9 billion tons of industrial waste is poured into the river annually. This seems like a huge amount of waste, but all this waste doesn't affect the quality of the river; not even for drinking. The waste does not affect the drinking water because it has such a massive flow. 5

THE WORK OF SCIENTISTS IN PROTECTING AQUATIC HABITATS Scientist's need to have a way to check make sure the habitat is healthy. One huge indicator that the lake or river is healthy is the level of dissolved oxygen. Plants and animals need the dissolved oxygen, because it is what they breathe. One way the level of oxygen in the river or lake can drop is when and animal decomposes. When all the oxygen has been used at the bottom of the lake, anaerobic bacteria keeps breaking down the materials and creates toxic hydrogen sulfide gas. A healthy level of dissolved oxygen is 6-10 mg/l. Another thing that scientist's must test is the temperature of the water. If there is a high temperature in the water, less oxygen can be stored in the water. Plus, a change so big as a change in temperature is very hard for a fish to adjust to and they die. Another test that scientist's do is the Secchi depth test, which tests the clarity and depth of a body of water. The test is done by lowering a black and white disk into the water and recording when it disappears. When rivers with a lot of nutrients get tested, the disks will disappear at around only 8- 3 feet. These are some of the main tests scientist's take. 6

THANKS FOR WATCHING! 7