Reach out an greet the various vertebrates and invertabrates that thrive in the Los Angeles River. This crayfish is only too happy to lend a hand. Kimball Garrett of the Los Angeles County Natural History Museum has completed a major report on the plant and animal life along the Los Angeles River. Most of the plants and wildlife inhabit the section between the Sepulveda Flood Control Basin and Frogtown. The constant supply of reclaimed water and many natural sandy bottoms in this section has promoted the return of life. Over 200 species of birds have been seen in the Sepulvada basin, and 125 species have been observed in Frogtown.

During most of the day this crayfish spends his time undercover. This time he has found a ledge as a hiding place in the Los Feliz region on the river. See if you can identify this invertebrate amongst these crayfish photos. During the day rock ledges and plants such as duckweed provide shade and cover.

Crayfish are not native to Southern California streams and have been introduced inadvertently by fishermen. Crayfish prey on amphibian larvae and are partly responsible for the decline in local toad and newt populations. The El Niño storms have temporarily washed out the crayfish in some local streams and now some endangered native amphibians like the California Newt and tree frog are making a comeback. 31

These small fish are possibly mosquitoe fish. Often distributed by Greater Los Angeles Vector Control to help reduce the number of mosquitoes by eating their larvae, these fish also eat amphibian larvae and so reduce the number of toads and newts.32

Many other types of fish are native to the arid western United States. The San Francisco Estuary Institute publishes on-line fishery survey forms and instructions to help interested groups who are interested in keeping track of local fish populations.

Nocturnal urban mammals visit the river at night to feed. What animal do you think left these tracks in the muddy shore? An educational organization called Earth Skills in Frazier Park conducts several good classes in animal tracking.

Biological Indicator Organisms
Insects too are attracted to the water and plants along the river. This brown damselfly is a biological indicator and can help tell us something about the health of the aquatic environment. The Kentucky Water Project has produced a list of biological inidicator organisms that can be used to conduct a biological survey of the pollution status of a river. Aquatic organisms are divided into three categories:

• Pollution Sensitive Organisms

• Pollution Intermediate Organisms

• Pollution Tolerant Organisms

Continue the tour here. So batten down your hard drives and cover your keyboards. The adventures of the urban river awaits you. Good Luck and remember, don't drink the water!

Yes! I like the Los Angeles River Virtual Tour, but my socks are wet and my feet are cold, so I would like to learn more about . . .

Copyright © 1995 Target Science