Spot on Science: What's an Algal Bloom?

Green sludge is taking over Lake Erie - what exactly is this gooey mess? Margaret explains what causes Lake Erie and other waters' algal blooms. 

Class Discussion Questions: 

1) What makes an algal bloom dangerous for people?

2) How does agriculture cause algal blooms?

3) Do you think the algal bloom also affects Canada? Why or why not?

Read the Script: 

One of these jars is filled with a tasty juice. The other is filled with a nasty surprise that was scooped right out of Lake Erie. Can you guess which one? Let me give you some clues by explaining what's going on in the lake. The western end of our Great Lake is covered with a big algal bloom. While bloom might sound pretty, it really means a huge amount of algae that just keeps growing and growing and growing. 

Now, algae are pretty simple water plants. Some might look more like seaweed, but others, like what's in our lake, look kinda like blobs of blue and green. They don't need too much to grow into big, happy blobs, just some light to use for photosynthesis, and some nutrients from the water. But what's been going on in our lake is not so great. The algae have found such a yummy environment that they are growing out of control into a harmful algal bloom. 

Now, a harmful bloom can suck up all the oxygen in the water and smother wildlife, block out light from getting to anything else that's in the water, and release toxins that can make the water unsafe to drink. That's a pretty big concern, since plenty of people rely on Lake Erie for their drinking water. 

So, what exactly are these tiny green plants finding so delicious in Lake Erie? It's mainly phosphorus and nitrogen that gets into the water. It comes from fertilizers that farms use to grow big crops, or that we use at home to make our grass soft and green. These chemicals eventually run off into the lake, and the water plants gobble it up. Add warmer waters from climate change and these plants can grow into monsters. 

Of course, we're not alone in experiencing algal blooms. Texas and Florida deal with them too. And in California, the algal blooms are a different species, and turn the water ruddy. People there call it the red tide. Yuck! In 2014, the algal bloom on Lake Erie leeched so many toxins into the water that Toledo was forced to shut off its water. 

This year's bloom on Lake Erie is being monitored carefully by researchers at the National Oceanic and Atmospheric Association and the U.S. Environmental Protection Agency. They've been watching on the ground and from space to make sure that the algal bloom doesn't make the drinking water for Toledo and other Northwest cities too toxic to drink. But I think I'm just gonna stick to my smoothie anyways.


Find Out More


Website Article: Missouri Botanical Garden, What Are Algae in Lakes and Ponds

Website Article: National Oceanic and Atmospheric Association, Harmful Algal Blooms | Explains why algae is harmful

Newspaper Article: New York Times, Miles of Algae Covering Lake Erie, Oct. 3, 2017 | Stunning photos of Lake Erie and Maumee River

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