Transcript:

Secrets of SedimentsAmbience: Ocean WavesCatalina Island, off the coast of Los Angeles, California, is home to a number of marine protected areas and a world class research facility that's visited every year by students and volunteers. We invite to put some earphones on and listen in as we join a research field trip on Catalina. I'm Jim Metzner and this is the Pulse of the Planet. Sadler: OK, so we don't need the binoculars right now.Woman's Voice: I'll take them.Lorraine Sadler isis a marine educator for the Wrigley Institute, and a consulting scientist for Earthwatch.Sadler: The mudflat area is a very unique place on the channel islands. The only one that we know of that actually has a population of fiddler crabs. As we go out you'll see the difference in the colors of the sediment. The stuff we're walking on right now is an algal mat. Where we have burrows that animals have burrowed in and excavated material that's come up, you can see it's a different color. That's due to the difference in the oxygen in the area that they're burrowing up. I'm going to try to dig down at least far enough to give us a little chance at looking at stratification. We can see where there have been excavations.. You can see the darker less oxygenated soil now on the surface. Here we have a hole dug by something. You can see the lighter material that's been oxygenated around the edge of the burrow? These kind of organisms can be called bio-turbators. They're disturbing the sediment so that you're getting more oxygenated layers. We'll hear more about Catalina in future programs. Our thanks to Earthwatch. I'm Jim Metzner and this is the Pulse of the Planet.