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Narrator: If we build more shallow water habitats will there be negative consequences? Could toxic selenium increase and poison the food web?
Robin Stewart: I do get asked questions, what is selenium? Some people have seen it as a vitamin supplement. And it’s true. You actually need selenium. It’s essential for life. It’s essential for your physiology. However at a certain point too much of it actually becomes toxic. It’s a potent reproductive toxin.
Narrator: Selenium occurs naturally in some west San Joaquin Valley soils.
Robin Stewart: The process of irrigation releases selenium and other salts from those soils directly into the San Luis Drain. This drain was connected up with the Kesterson National Wildlife Refuge. And what they found in the early 80’s was that when this connection occurred they saw over 60% deformity rate in bird hatchlings. It was a very acute and immediate toxic effect.
Narrator: CalFed plans to create new shallow water habitats where more food will be produced for wildlife.
Jan Thompson: Several years ago we did a study that showed that the detritus in the system is not a major source of carbon in the system. The major source of carbon is indeed the phytoplankton; the living plants in the system the microscopic forms. So, we’re concentrating a lot of our work now on phytoplankton, how they grow, how they get consumed and how they get transported through the system.
Lisa Lucas: This is a really simplified version of the food web we have going on here in these habitats. The phytoplankton are eaten by the clams. There are a couple of organisms in the delta that can eat them. There are some diving ducks that can actually munch through the thick shell and I believe sturgeon can as well. But, the zooplankton provide a really important food source juvenile stages of a lot of our native fish.
Narrator: The researchers need to understand the food web process to make sure that the new habitats will not have water that’s toxic to the very species they’re trying to protect.
Robin Stewart: Well these clams are really highly efficient accumulators of selenium. They scavenge it from the dissolved phase, but also from, more importantly from phytoplankton and we also know that they can also assimilate it from organic components of sediment. And because it’s such a good accumulator of selenium and it’s so abundant and available to upper trophic levels that it’s actually a vector for selenium getting from the dissolve source into upper trophic levels such as fish and diving ducks. So, not only does it play a role in the food web, but it also plays a role in contaminant transfer.
Narrator: How does water movement carry food resources like plankton and toxins like selenium between habitats in the Delta and Bay? This is another mystery. The answer ought to be simple. In rivers water should flow downstream. In the Bay water should move in and out with the tides. But in this system with all its water diversions the answer is far more complex and elusive.
Jon Burau: The people that were studying selenium, transport and transportation needed to know how Mildred Island was connected to the rest of the Delta, so people like us work with people like that to understand or provide a context for their research.
Nancy Monsen: Water transports everything else. So, unless you know where the water’s going you can’t predict anything else in the system.
Jon Burau: If I’m sitting at this Chip’s Island location and my cooler falls overboard, that cooler will go a mile upstream before it turns around. And then it will come back and it will come back almost as far as it went.
Nancy Monsen: What excites me about this is that you can look at really specific details of the system and we can ask a lot of what if scenarios. We can say, well what if we change the operation of a gate? What if we put in these barriers? What if we back off the pumping operation? What effect does that have on the system as a whole? So, before we go and spend millions of dollars out in the system flooding an island we can pretend that we’ve already flooded the island with our computer program.
Narrator: Breaching a levee so a river runs free. Removing a dam so salmon can return to their spawning grounds. Movements back to nature seem on the surface like good solutions but, maybe not. To restore habitats interdisciplinary science is critical. It takes the combined knowledge of biology, hydrodynamics, chemistry, geomorphology, physics and more. Working together, scientists strive to unravel the mysteries of an ecosystem by learning how all the parts work together like a complicated machine.
Paul Ehrlich: What you have here in California with a big project like this is really a microcosm of what we need in the world, interdisciplinary projects of scientists working with social scientists and working with politicians and the people are going to be necessary to keep the life support systems of our entire planet from going down the drain. We are heading in a direction which is totally unsustainable. If we don’t learn to do interdisciplinary science and then take advantage of the results, we’re not going to have a very nice future for our children and grandchildren.
Title: Delta Science: Excerpt from “Delta Revival”
"Delta Science" is an excerpt from the USGS produced television program “Delta Revival: Restoring a California Ecosystem”. A link to the complete program follows this description. The segment shows how USGS scientists are working to guide the restoration of the Sacramento-San Joaquin Delta through studies of ecosystem responses to toxic contaminants, invasive species and water diversions. The program aired on KPIX CBS 5 San Francisco and its affiliate channel in the spring of 2004. The program received the 2004 first place Telly Award in documentary and the first place Gold Screen Award in documentary from the National Association of Government Communicators.
Location: CA, USA
Date Taken: 5/1/2004
Video Producer: Stephen M. Wessells , U.S. Geological Survey
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A Production of: USGS and the California Bay/Delta Authority
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