In our discussion about the Arroyo Seco Watershed Health, we investigated the fo

Question

In our discussion about the Arroyo Seco Watershed Health, we investigated the following questions. 1. To prevent flooding, concrete channels were built to line the LA River and the Arroyo Seco, how does the construction of concrete channels affect streambed complexity and in turn the biodiversity? 2. When a section of the Arroyo Seco stream was tested, it was found to have an increased level of nitrates and phosphates. What may lead to an elevated level of nitrates and phosphates? What impact may it have on the organisms that live there? Discuss the impact on at least two trophic levels. 3. Name a pollutant that is found at the Arroyo Seco Watershed. List at least two potential sources of this pollutant. How might bioremediation be used to remove this pollutant? (Although you were not given the handouts used in class, try to use the Internet to help you answer this question. You don't need to provide a specific example of bioremediation.)

Explanation / Answer

1. all of is concrete there that no plant can living in, and no animal can burrow into there.seasonal flooding wash away everything every year. plants and animals. that need relative calm areas of water will be eliminated. Rooted plants and burrowing animals will be eliminated. Floating plants will be washed away. After a big rain, there is almost no life at all because it's all been scoured away in arroyo saco. Within months, filamentous algaes grow. Mayfly larvae eat that. There may or may not be a pond snail "bloom." There may or may not be small Gambusia mosquitofish introduced to keep the population of insects down. There may or may not be certain aquatic beetles (which also fly). Also note that channelization of ALL the streams that run into Los Angeles caused the extinction of the Pasadena freshwater shrimp. Their critical wetland habitat was replaced by a golf course, the Rose Bowl, and Brookside Park.

2.runoff of horse poop and dog poop from the trails ,street storm drains empty directly into the river, sending all sorts of street detritus there runoff of fertilizers from the golf courses.
acts as fertilizers for some producers and the filamentous green algaes grow longer. may poison some of the animals, e.g. fishes and pond snails.

3.Motor oil. Enough of that stuff poison some organisms, and what's left is able to tolerate the oil.
leaves, grass clippings, trash, also street runoff from storm drains. May provide habitat and food for some animals. May rot and stink and be a not-very-good habitat for others.
freshwater clams, Gambusias, pond snails, Louisiana crawdads. These live in the golf course streams, which have their overflow drain directly into the Arroyo Seco river

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