29.6.08

IT'S NOT WORTH IT. A Milwaukee Journal-Sentinel article asks readers to consider the potential loss of the Great Lakes.
What price would you put on our Great Lakes - the sand beaches and rocky shores; the salmon, perch and rainbow trout; the smell of a freshwater breeze? Should we give it all up so that international shippers can save about $55 million a year?
That $55 million figure appears to be valid.

Only about $55 million a year, in terms of transportation savings over truck, rail and barge alternatives, according to a 2005 Joyce Foundation-funded analysis of cargo flows on the Great Lakes. The study has been ferociously criticized by shipping interests as an overly simplistic look at a complex transportation system, but it was successfully defended before an independent panel of transportation experts.

"I don't think there is any disputing the study," says Dennis Schornack, a former President Bush appointee who served as U.S. chair of the International Joint Commission, a binational panel created to resolve boundary water disputes between the U.S. and Canada. "It was peer reviewed, and they say if anything it erred on the high side of the benefits."

Though the raw numbers indicate the public might be getting a raw deal, you are not likely to find protesters on the lakefronts.

This doesn't surprise Notre Dame biologist David Lodge, who has been working with economists for more than three years to find the shipping-specific costs tied to invasive species in the Great Lakes. He explains that most people are unaware of the scale of the problem. At the same time, the shipping industry that benefits from the traffic - and the ability to pollute - reaps most of the gain.

"The damages of invasions are spread thinly over every member of society, and the benefits of the status quo are more concentrated," Lodge says. "So the incentive to maintain the status quo is strong for the people who benefit, and the incentive on the part of society to advocate for change is small for each individual. So we don't get the political reaction."

What the article does not spell out is how small, in the scheme of things, that $55 billion is. I have been following the St. Lawrence Seaway story for some time. The overseas business for the Port of Milwaukee works out to fewer freight car loads per day than a now-abandoned Wisconsin electric railroad handled in its final years. Elsewhere, the traffic is bulk cargo in relatively small ships (ocean going tankers and container ships are larger than the Seaway permits) that serve as transportation for invasive species. The tankers will dock where the refineries are, on the coasts. The container ships will dock at Halifax, because the Canadian rail system can get those containers inland much faster than the ships can.

Meanwhile, the lake life appears headed for a Lotke-Volterra crash.

While politicians dawdle and scientists scratch their heads over how to keep the lakes safe from the next invader, a Darwinian drama plays out at a Pentium pace under the waves.

This year the U.S. Geological Survey released its annual prey fish survey for Lake Michigan, and it showed a jaw-dropping plummet in the numbers of little fish that sustain the lake's prized salmon and trout species.

The estimated "biomass," or overall weight, of prey fish in 1989, the year after the zebra mussel's discovery in the Great Lakes: about 450,000 tons. The estimated biomass now: about 31,000 tons. That's a drop in half from the approximately 60,000 tons recorded in 2006, itself a record low since the annual surveys began in 1973.

At the same time, there has been an explosion in the number and range of quagga mussels on the lake bottom. Quaggas were first documented in Lake Michigan in 1997, but remained a bit player in the lake's ecology until five years ago.

Quaggas have since squeezed out most zebra mussels and have expanded their range well beyond that of the zebras, which can survive only in shallower waters.

Quaggas are proving to be far more disruptive to the lake than zebra mussels, which must cling to a hard surface and normally don't live in water deeper than 75 feet. Quaggas can lurk at depths exceeding 500 feet and can make a living on both rocky and clay bottoms. Zebra mussels essentially formed a necklace around the lakebed's perimeter. Now quaggas are carpeting it.

As a result, the lake's invasive mussel numbers have increased a hard-to-comprehend 16-fold in just the past five years, and are spreading so fast that the biologists who make their living studying them have a hard time finding the words to describe what's happening.

"I've calculated that there are 380 trillion mussels in Lake Michigan," says Tom Nalepa of the National Oceanic and Atmospheric Administration. "That was based on estimates in 2005, and I know the quagga mussel population has increased three- to possibly fourfold over 2005, so you can multiply that by threefold. I don't even know what that number is. Quadrillions?"

Yes.

"It's clear as a bell, it's like distilled water out there," says University of Michigan limnologist and Great Lakes fishery expert David Jude. "But there are all these implications for the food chain, and we haven't seen the end of it all yet."

At this point nobody can say what the lake will look like when the population of quaggas finally plateaus.

But zebra and quagga mussels are already implicated in the demise of a fatty shrimp-like animal called diaporeia that once flourished on the bottom of Lake Michigan at densities as high as 20,000 per square meter.

Diaporeia have almost completely disappeared from vast expanses of Lake Michigan. Though scientists have yet to prove the link between their demise and the mussels' arrival, few doubt the connection.

This lost battle for the bottom of the food chain affects everything above it.

Lake Michigan's struggling whitefish are an example. The regional favorite at restaurant fish boils evolved to depend heavily on nutrient-rich diaporeia. The average weight of a 7-year-old whitefish was more than 5 pounds in 1988, the year zebra mussels were found in the Great Lakes. It has since crashed to barely a pound.

With their main source of food disappearing, whitefish are trying to eat the mussels, shells and all.

The likely outcome will be a collapse of the whitefish population. But when the quaggas exhaust their food supply, the quagga population collapses? The article mentions a seaweed called cladophora that prefers clearer water. What is cladophora's food supply? What fish use cladophora for food?

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