Great Lakes Under Threat. Are Lake Erie’s Bad Old Days Back?
September 21, 2011
..a research technician at the University of Toledo’s Lake Erie Center, dangles a long, white plankton net off the side of the boat, then hauls it in and filters the sludgy water into a canister for testing back in the lab. “Dogs get sick when they drink this,” he says: three in Ohio died last year after swimming in a contaminated inland lake not far from here, and nine people got sick (including one with memory loss and partial blindness) after skin contact.
After a decades-long absence, blue-green algae is again flourishing in Lake Erie — and it’s never been worse than it is this summer. The algal infestation is just one of many factors that biologists in Ohio, Michigan, and elsewhere say are pointing toward an ecosystem in danger of collapse.
The lake’s center contains a growing dead zone, devoid of oxygen during summer months. Invasive species such as zebra and quagga mussels are wreaking havoc with its ecology. The fish that make Lake Erie a tourism draw, including yellow perch and smallmouth bass, are seeing their predators grow and their habitats shrink. Ducks, loons, and mergansers that feed on lake fish have died in recent summers from botulism poisoning. Swimmers in some areas have been advised this year not to swallow the water.
Erie is the most fertile of the Great Lakes: It contains only 2 percent of their water but 50 percent of their fish. Its biological abundance, and its location in a densely settled corner of the Midwest, make the prospect of collapse all the more frightening. If conditions grow worse, imploding native fish populations could decimate Lake Erie’s recreational fishing industry. (Fishing generates $7 billion a year throughout the Great Lakes.) The water supply for 11 million people could become undrinkable without expensive treatment. And blue-green algae, linked to liver cancer in China and fatal poisonings in Brazil, could pose a grave threat to people here, too, particularly if ingested.
I asked Alan Steinman, Director of the Annis Water Resource Institute at Grand Valley State University some further questions:
Q. A lot has been written about warming in Lake Superior (and my own anecdotal report is, oh my gosh, is it ever!) – do we have good info about warming in the lakes as a whole? and has anyone done a projection for what that means in 50 years? 100 years?
The warming has not been as dramatic as in Superior, but there is general warming going on throughout basin. Both NOAA and EPA maintain those data bases. There is a lot of modeling going on regarding projections. The main problem is taking the global circulation models and “downscaling” (i.e., applying them at a finer spatial resolution) them to the Great Lakes. There is a lot of uncertainty associated with the downscaling. The IJC’s Upper Great Lakes Water Level Study is focused on that–reports available at www.iugls.org. The models are not totally consistent, which is pretty typical, but generally show water levels going down (but not all of them!), with warmer climate and more precipitation (but clustered into major episodic events).
Q. Can we say definitively that the microcystis problem (algae toxins mentioned above) is exacerbated by climate change?
No, we cannot state that. It is a contributing factor (they like warmer temperatures) but it is also very likely that increased nonpoint source pollution and dreissenid mussels (zebra and quagga – invasive species) are also important factors.
Dr. Steinman was a member of a team which recently discovered Cylindrospermopsis raciborskii, a toxin forming micro-organism, formerly associated with more southerly climates, surviving in a tributary of Lake Michigan. In a 2006 paper, Steinman observed:
C. raciborskii is able to produce multiple toxins, and was implicated in one of Australia’s worst cases of human poisoning (Falconer 2001). At least three distinct toxins can be produced by Cylindrospermopsis (Chorus and Bartram 2004): cylindrospermopsin, which targets primarily the liver and kidneys, and anatoxin-a and saxitoxin, which are both neurotoxins.
Because of its potential to produce these toxins and its highly adaptable growth, this genus ranks near the top of the watch list of toxic cyanobacteria for water managers (WHO 1999).
Significant reductions in Great Lakes water levels, which are projected under higher emissions scenarios, lead to impacts on shipping, infrastructure, beaches, and ecosystems.
Higher temperatures will mean more evaporation and hence a likely reduction in Great Lakes water levels. Reduced lake ice increases evaporation in winter, contributing to the decline. This will affect shipping, ecosystems, recreation, infrastructure, and dredging requirements. Costs will include lost recreation and tourism dollars and increased repair and maintenance costs.
The likely increase in precipitation in winter and spring, more heavy downpours, and greater evaporation in summer would lead to more periods of both floods and water deficits.
The projected pattern of increasing precipitation in winter and spring and heavy downpours is expected to lead to more frequent flooding, increasing infrastructure damage, and impacts on human health. Heavy downpours can overload drainage systems and water treatment facilities, increasing the risk of waterborne diseases. In summer, with increasing evaporation and longer periods between rainfalls, the likelihood of drought will increase and water levels in rivers and wetlands are likely to decline.
The “heavy downpours” mentioned by Dr. Steinman, and the US Global Change Research group, are illustrated by the graph below, which shows that the increasing in the intensity of individual precipitation events was already measurable in the late 1990s. This kind of event leads to more water pollution pressure on the lakes, by increasing runoff – as soils quickly saturate and are unable to absorb additional moisture, overwhelming storm sewer systems, which has caused an increase in the number of beach closings around metropolitan areas.
So, climate change is a “force multiplier” which increase lake impacts from a number of different vectors.
A Commenter pointed to a video illustrating phosphorus runoff into Lake Erie. No mention of climate change here, as the focus is on nutrients – useful though, for weekend Limnologists.