By Dr. Robert Thorson

I’m not much of a bird-watcher. But I’m a devoted and appreciative observer of the common loon. Every time I see its black-and-white beauty, hear its eerie wail or watch its deep-water diving is a blessing. Each cry of the loon is precious to me.

So news that they’re being poisoned by the thousands and washing ashore in the upper Great Lakes, mostly in northern Michigan, is devastating. Don Gardner of the Oakland Press, a small city north of Detroit, reported the story Jan. 7.

This timely story from far away is an example of how ignorant we can be of the environmental consequences of seemingly small things. In this case, the exchange of ship’s ballast water created a thorny problem for two nations, eight U.S. governors, 16 senators, an untold number of mayors and loon lovers everywhere.

Such uncertainty is the Achilles heel of our mandatory environmental impact evaluation process. Developers of large projects must identify, discuss and sum up the predicted impacts for a variety of alternatives. The University of Connecticut just did this for its proposal to build a water pipeline to Storrs. To meet the letter of the law, UConn hired an engineering contractor who made dozens of predictions for seven specific alternatives. The question “Did they get it right?” haunts every such analysis.

The Michigan story involves one nerve toxin, three invasive species and five links in the food chain. It begins with two invasive freshwater mussels, the zebra and the quagga. While these create their own major problems for navigation infrastructure, they actually improve water clarity by straining phytoplankton through their gills. Deeper penetration of sunlight into lakes allows the deeper growth of algae, leading to dense organic mats in circumstances where the supply of oxygen becomes limiting. At that point, microbial metabolism switches from aerobic to anaerobic, fostering the growth of bacteria responsible for E-botulism, a paralytic nerve toxin.

Enter the round goby, a small, seemingly innocuous invasive fish. It arrived in the Great Lakes more than 20 years ago in ballast water, proliferated and has survived quite well feeding in the degraded environments of the algal mats, displacing native fish.

The goby tolerates the neurotoxin. The loons and other fish-eating birds do not. After ingesting a meal of gobies, their muscles begin to fail. First they can’t fly. Then they can’t hold their heads up. Then they drown.

Gardner reported about Gulliver, a small town on Michigan’s Upper Peninsula, where, for two weeks in October, 302 loons washed up on a seven-mile beach. That’s 43 dead loons per mile or one every 123 feet. In another study in Whitefish Bay, where loon migration has been monitored since 1984, the number of birds is on its way down.

Massive loon die-offs are new since 2006. This year’s is the worst on record. “Atrocious,” according to the co-director of the Whitefish Bay study. Last year’s record heat and drought no doubt played a role, likely fostering excess algal growth.

And to make things worse for us all, most of the dying loons are probably not Michigan breeding pairs. Rather, they were just stopping in Lake Michigan to feed during their annual migration to more southerly waters along the Atlantic coastal plain or the U.S. Gulf Coast. This makes Lake Michigan a deadly pit stop for loons coming from healthy lakes. In short, if you like northern lakes and ponds, your favorite loon might not return because it was poisoned by a problem created by someone else.

Many of the dead loons had just entered their first year of breeding maturity with a long life expectancy ahead of them. This compares with the early 20s of our sons and daughters, who are just heading out to make their way in the world. What a tragic stage at which to be stopped dead.

I don’t have a solution. I write to remind you to stay on guard. What your neighbor does to the environment will impact you in ways that may be impossible to predict.