Researchers map 34 threats to the Great Lakes

Dec 18, 2012

The Great Lakes are under a lot of stress. 

34 different kinds of stress, to be exact.

That’s according to a research team that has produced a comprehensive map showing many of the things that stress the Great Lakes.  Think: pollution, invasive species, development and climate change... just to name a few. 

To learn more about this new map, I went to visit David Allan. He’s a professor in the School of Natural Resources and Environment at the University of Michigan, and he’s one of the people who led the project.

I asked him why he wanted to take on something like this:

"We set out to answer the question, what are the most important stressors in the Great Lakes, what’s the cumulative influence of environmental stressors in the Great Lakes, and what’s their spatial distribution – how do they vary from place to place? And we did that with the help of many by developing individual maps with 34 different environmental stressors; they represent invasive species and climate change and coastal development and contaminated sediments and land runoff, and we developed these individual stressor maps and then we combined them in a variety of ways but basically summed their influence so that we have the first ever spatial pattern of cumulative impact of humans on the Great Lakes," Allan says.

If you look at the map above, you can see that there's an awful lot of red in Lake Erie, for example. Allan explains that their "stress index" depicts relative stress - for example, there are more environmental stressors affecting Lake Erie than there are in Lake Superior.

"So, Lake Erie certainly shows up as one of the lakes that has the highest value for our stress index. I don’t think that’s a big surprise to anyone. What is surprising though is the number of stressors that influence these coastal waters in particular. I think these coastal waters are most strongly stressed because they’re experiencing stressors that are occurring in the lakes themselves like invasive species and contaminated sediments, and they experience all the runoff from the land and all the aquatic habitat disruption that goes with coastal development.  And so, we’d have to look at the numbers to tease it out but there might be 18 or 20 or more of our stressors all having an influence on some of those coastal waters of Lake Erie, and that’s what gives it the red appearance on our map.  It’s the significantly larger number of stressors that are co-occuring in those locations."

But it's not all doom and gloom. David Allan says there's a lot of good restoration work happening.

"Right now, we are in the middle of a really important and useful set of activities called the Great Lakes Restoration Initiative and it’s invested over a billion dollars of federal money in Great Lakes restoration.  So, restoration is a mix of activities. We did another set of mapping.  We mapped all the locations that we could identify where restoration is taking place.  And we asked the question, would we have picked those places as well, and the answer was yes.  So, those restoration dollars are being invested in locations that we agree are places that are red on our map, they are places of high stress.  They tend to be places also that provide a lot of benefit to humans.  So, it’s a good thing that it’s taking place."

*Editors note*

In 2005, we produced a multi-part series called "The Ten Threats to the Great Lakes."

Those "ten threats" were broken down into multiple parts, which resulted in a 33-part series.

It was quite a format breaker for a system used to a five-part series at most.

So when we heard the news about the '34 threats,' it brought back memories of the series we lovingly dubbed "The 33 threats to the Great Lakes." We were outdone by one.