Nature Watch: Botulism outbreak threatens to decimate common loon population - The Buffalo News
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Nature Watch: Botulism outbreak threatens to decimate common loon population

A symbol of wilderness is the common loon. I hope that some of you had a chance to interact with these wonderful birds on their nesting grounds this summer. Did you have the opportunity to observe the adults’ handsome black-and-white pattern with their distinct necklace, their big bill and their bright red eyes? Did you see young birds clinging to their backs or paddling around their parents? And, even more important, did you hear the loons’ distinctive yodeling and wailing and laughing through the evening and early morning hours or just before and after a storm?

I hope you did because your chances of being able to do so in the future are decreasing significantly. Loons are threatened by a disease that is killing thousands during their migration through this region between their summer breeding grounds to our north and their wintering grounds in the southern states and the Gulf of Mexico.

Rick Taylor has summarized the problem in an essay that appeared on several Michigan websites. I draw on his analysis here.

The recently introduced zebra and quagga mussels filter lake water very rapidly. Today we can see much deeper into our Great Lakes than we did in the past. Unfortunately, what appears to be a positive feature has a downside as well. The problem is that the clearer water allows the sun to penetrate to the bottom of shallow lake regions, allowing algae mats to photosynthesize and grow there. Those mats are now many feet thick.

While the top layer of algae is getting sunlight, the lower layers do not and they die and decay. Currents and wave action skim off the live surface of these beds, driving it ashore and leaving tons of algae decomposing on the lake bottom. It is in that soup where the botulism E. bacteria grows and produces its deadly toxin.

The round goby, an introduced fish that grows to about the size of your thumb, swims through this decomposing algae to feed on worms and bugs that have ingested the toxin from the rotting algae. Then diving birds like the loon and double-crested cormorant dive down to eat the goby and other deep-swimming baitfish. Working up the food chain, the botulism E. neurotoxin affects the central nervous system of any bird or animal that ingests it, causing paralysis. Birds often drown because they can’t keep their heads above water.

One estimate has 100,000 birds killed by this virulent toxin in Lakes Erie and Michigan, through which the loons migrate. Here are two things you can do to help:

1.) Participate in the 28th Annual Great Lakes Beach Sweep from 10 a.m. to noon on Saturday. Volunteers of all ages are invited to join the Ocean Conservancy International Coastal Cleanup in the largest volunteer environmental event in the world. For more information call Sharen Trembath, Lake Erie coordinator, at 549-4330, or visit

2.) Use care in choosing the fertilizer for your gardens and farm crops. Fertilizer is labeled with three numbers, like 4-8-6. Those numbers represent the percentage of nitrogen (N), phosphorus (P) and potassium (K), with the remainder – in this case 82 percent – other ingredients and filler. Nitrogen and phosphorus contribute to the growth of algae, so you should choose fertilizer with low or zero potassium (the middle number) and with slow-release nitrogen.


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