In the science of ecology, a network of inter-dependent, predator-prey relationships is known as a “food web”. For ecologists, one of the most crucial problems to solve is identifying the consequences (to the web, or ecosystem) when one species goes extinct. What’s more, certain species seem to be more critical in keeping these webs functioning; when they go extinct, they cause one or more co-extinctions. But due to these complexities, determining which species in a given web is the most critical (most likely to cause a cascade of extinctions) is very difficult.

And, it’s not like you can just “Google it”…Well, it is actually. More precisely, you’ll want to use Google’s Page Rank algorithm — after you’ve tweaked it a bit — as discovered by ecologists  Stefano Allesina and Mercedes Pascual.

Two ecologist discover that by adapting Google’s Page Rank algorithm they were able to “reverse engineer” the collapse of food webs, and thus determining which species in a given web are most critical to the web’s existence.

Publishing their results in the journal PLoS Computational Biology*, ecologists Stefano Allesina and Mercedes Pascua reveal their successful application of a modified “eigenvector” (a type of ranking algorithm) in determining which species’s extinction was most likely to cause the most number of co-extinctions, and thus critically damaging, or even collapsing, the entire food web.

The extinction area is the area described by the area below the curves.

(above) The area can take values from (no secondary extinctions in response to the removal of species) to 1 (all species go extinct after the first removal). The axis represents the fraction of species removed in the numerical experiment, while the axis is the fraction of species that are extinct as the result of these removals. The example uses the St. Mark’s food web [29] and the (red) and (blue) algorithm.

Their modified algorithm (based on what Google uses to rank web pages), termed the EIG algorithm, permitted the researchers to order species according to their importance for coextinctions, providing “the sequence of losses that result in the fastest collapse of the network.”

There are many models used to predict food web and ecosystem interactions and extinctions, but this new approach identifies the subset of coextinctions that is common to “all possible models”, that is, those extinctions that will happen, with certainty, given the loss of a prey species of any given predator species.

Modification of food webs from ecological considerations to satisfy the two constraints required for application of the EIG algorithm

(above) A special node is added to the food web by connecting this “root” to the primary producers. Every species in turn connects to the root to represent the buildup of detritus (dashed line). Right) The analysis can be improved by removing the “redundant” connections that do not contribute to robustness (dashed, in red).

Further, while their model is also based upon network structure, it is more accurate in identifying extinction sequences than previous models wherein species importance was based upon “hubs”, or the number of connections.  They also found that their algorithm out-performed a genetic algorithm (also adapted for ecological analysis) capable of processing millions of sequences.

While their are many links in a food web, not all such links contribute to the robustness of that web. The adapted EIG algorithm simply finds the most efficient route to system collapse.  Concluding their findings, the scientists assert: “The algorithm works in this sense better than all the others previously proposed and lays the foundation for a complete analysis of extinction risk in ecosystems.”

This modified algorithm will become an increasingly important tool in the years ahead as scientists and environmental policy experts seek to identify areas of greatest concern for funding of research and ecological preservation and restoration.

* ‘Googling Food Webs: Can an Eigenvector Measure Species’ Importance for Coextinctions?’, Stefano Allesina¹, Mercedes Pascual, PLoS Computational Biology, Sept. 4, 2009

top diagram: Diagram showing aquatic and terrestrial food webs; Creative Commons CC0 waiver.

middle chart: Allesina, Pascual – under a Creative Commons Attribution License.

bottom chart: The Authors, under a Creative Commons Attribution License.

Continuing on with our Going Green Tips series, Going Green Tip #6 should be no surprise (we’re starting with the big boys). The general tip is to stop using coal power. Easier said than done, right? Maybe, but it is VERY important, and there are a lot of reasons why it’s easier now than ever.

Although it would be fun to talk about all the great energy sources and programs you can use to cut the coal, I think I will save those for future going green tips posts. In this one, I’ll focus on why cutting the coal is so important (so that everyone is clear on why this is such a high priority).

To start with, here is a nice intro on what coal is from the Power Scorecard:

Coal is the solid end-product of millions of years of decomposition of organic materials. In truth, coal is stored solar energy. Plants capture the energy from sunlight through photosynthesis, which directly converts solar energy to plant matter. Animals that then eat the plants to convert that energy again, storing it in their own bodies.

Over millions of years, accumulated plant and animal matter is covered by sediment and stored within the earth’s crust, gradually being transformed into hard black solids by the sheer weight of the earth’s surface. Coal, like other fossil fuel supplies, takes millions of years to create, but releases its stored energy within only a few moments when burned to generate electricity. Because coal is a finite resource, and cannot be replenished once it is extracted and burned, it cannot be considered a renewable resource.

One major issue with the burning of coal is that it is a leading contributor to global warming pollution. In fact, 73% of carbon dioxide emitted from electricity generators comes from coal power plants.

But coal is also a major source of numerous other environmental problems.

• “[C]oal power plants are responsible for 93 percent of the sulfur dioxide and 80 percent of the nitrogen oxide emissions generated by the electric utility industry…. These emissions spawn the acid rain that is eating away red spruce forests in the Northeast and Appalachia, and rob previously pristine streams of brook trout and other fish species in the Adirondacks, upper Midwest and Rocky Mountains,” the Power Scorecard reports.
• “Coal emissions also cause urban smog, which has been linked to respiratory ailments,” the Power Scorecard adds.
• “Coal plants are also a major source of airborne emissions of mercury, a toxic heavy metal…. In the West, about 87 percent of coal is removed from the earth through strip mining, which can contaminate soils with heavy metals and destroy near-surface aquifers. In the East, coal is sometimes mined by removing entire mountain tops to more easily extract the subsurface mineral reserves.”

The Union of Concerned Scientists, which also delves into the massive environmental damages related to coal mentioned above in much more detail, reports that, “Coal generates 54% of our electricity, and is the single biggest air polluter in the U.S.”

Coal and Human Health

Even if you care not for the environment at all, the human health consequences of all of this are humongous. And if you actually took those (alone) into account, the price of coal would be almost twice as high. “In 2005, the health damages caused by coal power cost $120 billion” (emphasis added).  Unfortunately, we don’t take the price of our health problems or the price of the environments we destroy into account, and our governments actually subsidize coal to a great degree.

But, you can take these issues into account and can switch to a cleaner power source, yourself. And, at the least, if you are financially strapped and have no affordable options in your area, you can cut your energy usage, in general, which is good for addressing all of the concerns above and is also good for your finances.

Perhaps this should have come earlier in our series, but without a doubt, cutting coal is a major “going green tip,” and something I think we will come back to repeatedly in this series.

Photo Credits: DerGuy82 via flickr & Stuck in Customs via flickr

We’ve had a couple posts on sea otters on this site recently — a 10 Friday Photos post on otters and a post about the declining sea otter populations in California.

I have to be honest and let you know that one particular friend has been the driver behind these posts. She also recently recommended that we do one more post on a “Help Sea Otter Populations Recover” petition, since our “Planetsave readers love otters!”

The truth is, our readers do seem to love otters (these posts have done fairly well) — and who wouldn’t?! And otters do need our help.

Sea Otters in Trouble

“Southern Sea Otter populations have been dropping drastically for almost ten years. High mortality rates and low birth rates have scientists worried about the species itself and the repercussions this population drop will have on the food chain,” the intro to the petition states. “Sea Otters face immense challenges with food scarcity, disease and contamination in their waters. These and other factors need to be researched and addressed immediately in order for the populations to safely recover.”

Sea otters need our help and a great legislative proposal, the Southern Sea Otter Recovery and Research Act, would go a long way in funding the help needed. So, write to your Senators today via a petition sponsored by Care2 on the petition site to do your part and help sea otter populations recover (if you care about these adorable creatures and the ecosystems they are a part of). It is the least we can do to help these cute creatures survive.

And a big thank you to Becky Striepe (editor of our sister site, Eat.Drink…Better.) for the story idea.

Photo Credit: mikebaird via flickr

Fox thought to be extinct found in California.

Three weeks ago, U.S. Forest Service biologists thought they found a fox in the mountains of central California that is supposed to be extinct.

The biologists looked to experts at the University of California, Davis to confirm this finding. Sure enough, the fox they stumbled across was this thought-to-be-extinct fox, a Sierra Nevada red fox (Vulpes vulpes necator).

How the Sierra Nevada Red Fox Was Found & Identified

Photographs of the fox were taken by a Forest Service trail camera near Sonora Pass and showed the fox biting a bait bag of chicken scraps. The bait bag was shipped to two expert wildlife genetics researchers working in the UC Davis Veterinary Genetics Laboratory, Ben Sacks and Mark Statham. Regarding these researchers, UC Davis writes: “Since 2006, they have radically altered our understanding of red foxes in California, supplying information crucial to conservation efforts.”

Analyzing DNA from saliva they scraped off the tooth punctures on the bag, Sacks and Statham confirmed that the spotted fox was definitely a Sierra Nevada red fox.

“This is the most exciting animal discovery we have had in California since the wolverine in the Sierra two years ago — only this time, the unexpected critter turned out to be home-grown, which is truly big news,” Sacks said. (The wolverine found in the Sierra Nevada “was an immigrant from Wyoming,” UC Davis reported.)

UC Davis wildlife genetics researcher Ben Sacks holds a native Sacramento Valley red fox (Vulpes vulpes patwin)

California Red Fox Research and Findings

Sacks and his colleagues are leaders in California red fox research. Some of their key research and findings are as follows:

Four years ago, Sacks began analyzing California red fox DNA collected from scat, hair and saliva from live animals, and skin and bones from museum specimens. Until then, the expert consensus was that any red fox in the Central Valley and coastal regions of the state was a descendant of Eastern red foxes (V.v. fulva) brought here in the 1860s for hunting and fur farms.

Sacks and his colleagues have confirmed that red fox populations in coastal lowlands, the San Joaquin Valley and Southern California were indeed introduced from the eastern United States (and Alaska). But they have also shown that:

* There are native California red foxes still living in the Sierra Nevada.
* The native red foxes in the Sacramento Valley (V.v. patwin) are a subspecies genetically distinct from those in the Sierra.
* The two native California subspecies, along with Rocky Mountain and Cascade red foxes (V.v. macroura and V. v. cascadensis), formed a single large western population until the end of the last ice age, when the three mountain subspecies followed receding glaciers up to mountaintops, leaving the Sacramento Valley red fox isolated at low
elevation.

With so many species going extinct these days, it is great to see one “coming back to life.”

Photo Credits: Keith Slausen and UC Davis, respectively

A University of California LA geographer notes in book that northern countries such as Canada, Scandinavia and Russia are likely to thrive and become formidable economic powers.

Laurence C. Smith writes in “The World in 2050: Four Forces Shaping Civilizations Northern Future” that northern countries and some northern states of the US will become large economic powers and migration magnets.

“In many ways, the New North is well positioned for the coming century even as its unique ecosystem is threatened by the linked forces of hydrocarbon development and amplified climate change,” writes Smith, a UCLA professor of geography and of earth and space sciences.

Smith also makes several other predictions which the UCLA note below;

New shipping lanes will open during the summer in the Arctic, allowing Europe to realize its 500-year-old dream of direct trade between the Atlantic and the Far East, and resulting in new access to and economic development in the north.

Oil resources in Canada will be second only to those in Saudi Arabia, and the country’s population will swell by more than 30 percent, a growth rate rivaling India’s and six times faster than China’s.

NORCs will be among the few place on Earth where crop production will likely increase due to climate change.

NORCs collectively will constitute the fourth largest economy in the world, behind the BRIC countries (Brazil, Russia, India and China), the European Union and the United States.

NORCs will become the envy of the world for their reserves of fresh water, which may be sold and transported to other regions.

Read more about what Smith has to say at the UCLA website, but this book is definitely on my to read list.

Source: UCLA

A new report issued by US environmental and scientific federal agencies suggests that there is a growing thread of hypoxia in US waters.

Hypoxia is a condition which sees oxygen levels in the water decrease to a point which stresses or kills the animal and bacterial life living therein.

“The Nation’s coastal waters  are vital to our quality of life, our culture, and the economy. Therefore, it is imperative that we move forward to better understand and prevent hypoxic events, which threaten all our coasts,” wrote Nancy H. Sutley, chair of the Council on Environmental Quality, and John P. Holdren, Director of the Office of Science and Technology Policy, in a letter accompanying the 163-page report, Scientific Assessment of Hypoxia in U.S. Coastal Waters, which was delivered today to Congressional leaders.

The National Oceanic and Atmospheric Administration, or NOAA, wrote;

The interagency report notes that incidents of hypoxia—a condition in which oxygen levels  drop so low that fish and other animals are stressed or killed—have increased nearly 30-fold since 1960. Incidents of hypoxia were documented in nearly 50 percent of the 647 waterways assessed for the new report, including the Gulf of Mexico, home to one of the largest such zones in the world.

Read more about the research and the report here. But given the increase worldwide of dead zones and oxygen depleted areas one can only hope that some measure of research and policy steps are taken to reverse the trend.

Source: NOAA
Image Source: eutrophication&hypoxia