TERC Clam Barrier Installation.

A call to arms was issued Friday, and was answered by scientists as well as federal, state and regional volunteers to help stamp out an invasive species of clams which are threatening to slime one of the most pristine lakes in the world.

A $1.4 Million experiment was cooked up by top researchers from the University of Nevada, Davis and the University of California, to help eradicate hundreds of thousands of these invading clams in Lake Tahoe. These are non-Native Asian clams (Corbicula Fluminea) which excrete concentrates into the water which promote algal growth.

The plan is to basically to smother them, they will be utilizing giant rubber mats, to try and ensure that these little invaders don’t have a chance to upset the delicate balance of the lake. These rubber mats are going to cover an astonishing acre of lake bottom, an operation of this scale has never been attempted before, but the situation calls for drastic action. The first half acre of mat was splashed down into the Marla Bay near Zephyr Cove, and the other half acre will be plunked down at Tahoe’s Lakeside Marina. It is hoped that the mats will deprive much needed oxygen from the clams, and they will die off quickly. “You have to think of these clams as sucking factories,” explained the director of the UC Davis Tahoe Environmental Research Center, Geoffrey Scladow, “They suck in the water and they filter out the algae. Their excretions are highly concentrated packages of nutrients.”

This invasive species of clam was first discovered in 2002, however it is only recently that they have been taken seriously as a threat to the ecology of the lake, as well as it’s world renowned clarity.

For the first time in history, scientists* have succeeded in measuring the physiology of marine phytoplankton through satellite measurements of its fluorescence. With this new tool, it will become possible for researchers to continuously keep an eye on the ocean’s health and productivity. Since it is based on satellite images the method works all over the world.

“Until now we’ve really struggled to make this technology work and give us the information we need,” says Michael Behrenfeld, an Oregon State University professor of botany. “The fluorescence measurements allow us to see from outer space the faint red glow of tiny marine plants, all over the world, and tell whether or not they are healthy. That’s pretty cool.”

Knowing how the world’s phytoplankton populations are doing doesn’t only tell us about the plankton it self; it also provides us with valuable clues that can help us assess a long row of other processes on the planet. By studying phytoplankton, it is for instance possible to learn about climate change and desertification.

* The break through is the result of the successful collaboration of Oregon State University, the NASA Ocean Biology and Biogeochemistry Program, the NASA Goddard Space Flight Center, University of Maine/Orono, University of California/Santa Barbara, University of Southern Mississippi, Woods Hole Oceanographic Institution, Cornell University, and the University of California/Irvine.

Genetic pattern analysis strongly suggests that California and British Columbia urchins are not connected via larval dispersal and comprise two distinct populations. Sea urchins have one of the longest larval periods of any known marine invertebrate and it has therefore been tempting to assume that ocean currents must be mixing urchin larvae all over the place, making it difficult for any distinct populations to form. But research results from the University of California now indicate that these two Pacific populations are two clearly separated ones.

Sea urchins –  Picture from the Red Sea

Together with former* graduate student Celeste Benham, marine biology professor Ron Burton of the University of California at San Diego have analyzed 500 adult sea urchins from Californian waters across five microsatellite markers and then compared the genetic patterns to an existing, similar database of 1,400 urchins from British Columbia. The Californian specimens were collected off the coast of San Diego, Los Angeles and Mendocino counties.

The genetic signatures found by Burton and Benham strongly suggest that the southern and northern populations are not connected via larval dispersal.

“From my evolutionary perspective, our results are important because they imply that, even on long time scales, there is no mixing, Burton explains. This means there is at least the potential for populations to adapt to different ocean conditions and gradually diverge. This is the first step in the two populations potentially becoming different species.”

This is the first time scientists have detected any population structure in the species. Similar studies carried out in the past have used fewer genetic markers and found no population genetics structure in the species despite having tested many different patches across its range.

“The take-home message of this study is that if you use more markers and newer techniques you will find some population differentiation that before nobody found,” says Burton.

* Benham is now a research assistant at the marine mammal laboratory at Hubbs-SeaWorld Research Institute in San Diego.

“Every single spot of the ocean along the West Coast is affected by 10 to 15 different human activities annually”, says Ben Halpern, a marine ecologist at the National Center for Ecological Analysis and Synthesis (NCEAS) at the University of California at Santa Barbara.

In a two-year long study, Halpern and his colleagues have documented the way humans are affecting the ocean off the West Coast of the United States. The research team has overlaid data on the location and intensity of 25 human derived sources of ecological stress, including commercial and recreational fishing, land-based sources of pollution, and climate change. The information has been used to construct a composite map of the status of West Coast marine ecosystems.

“We found two remarkable and unexpected results in this research,” says Halpern. “Ocean management needs to move beyond single-sector management and towards comprehensive

ecosystem-based management if it is to be effective at protecting and sustaining ocean health. Also, the global** results for this region were highly correlated with the regional results, suggesting that the global results can provide valuable guidance for regional efforts around the world.”

The study results show that hotspots of cumulative impact are located in coastal areas close to urban centres and heavily polluted watersheds.

“This important analysis of the geography and magnitude of land-based stressors should help focus attention on the hot-spots where coordinated management of land and ocean activities is needed,” said Phillip Taylor, section head in NSF’s* Division of Ocean Sciences.

You can find more information in the article from the research team published in the journal Conservation Letters on May 11. The project was conducted at NCEAS, which is primarily funded by NSF’s Division of Environmental Biology.

* National Science Foundation (NSF)

** The lead scientists on the U.S. study have already carried out a similar analysis on a global scale; the results were published last year in Science.