Transcript: What causes algae blooms? | Nov 12, 2018

(Dramatic music playing)

Aerial views show images of a lake.

A caption reads "Lake Erie has a problem so big you can see it from space."

A satellite view shows a fluorescent green area in the lake.

The caption changes to "Blue-green algae."

A newspaper article headline reads "250,000 football field of green algae now cover lake Erie."

Another headline reads "Harmful algal blooms continue to plague Lake Erie, threaten drinking water, fish, pets."

A third headline reads "This year's Lake Erie algae bloom was as big as NYC, scientists say."

The caption changes to "The tiny cyanobacteria can produce harmful toxins that can cause skin rashes, stomach pains, or even liver damage."

A sign reads "Do not drink water. Not safe for drinking."

The caption changes to "IT can also be deadly for animals.

An article headline reads "Blue-green algae confirmed as cause of dogs' sudden deaths in Fredericton."

The caption changes to "The algae eventually sinks and uses up oxygen to decompose, creating hypoxic zones that suffocate aquatic life. Shallow Lake Erie is the most vulnerable of the Great Lakes because its shallow waters heat up faster. And warm temperatures fuel blue-green algae growth. Yet blue-green algae appears in other lakes, too, because of excess phosphorus."

An article appears with the caption "Algae bloom in Lake Superior raises worries on climate change and tourism."

The caption changes to "What is phosphorus?"

The caption changes to "Andrea Kirkwood. Biology professor, University of Ontario Institute of Technology."

An audio plays.

Andrea says "It's a nutrient that algae requires so if there's not a lot of it, there won't be a lot of algae."

The caption changes to "Fifty years ago, this phosphorus came from city sewage and dish detergents, so Canada and the United States restricted phosphates and improved sewage treatments."

A bar chart with the title "Western Lake Erie Bloom Severity" shows the increase from the year 2003 to 2017.

The caption changes to "But the blooms came back. As climate changes leads to more intense rains, thaws and floods, phosphorus-rich fertilizers and stormwater runoff are washed into waterways. Adding to the problem: a build-up of phosphorus in soils, riverbeds and lakebeds."

Andrea says "Its's this legacy phosphorus, the phosphorus that's been trapped in the soil over a long period of time, trapped in the sediments over many decades, that's kind of what we're dealing with, and it is much harder to manage."

The caption changes to "A problem years in the making won't be solved anytime soon. Scientists doubt the goal of reducing phosphorus 20 percent by 2020 can be reached, but every little bit helps. New technology being developed in Ontario is leading the way."

A map shows the location of Chatham-Kent."

A headline reads "New phosphorus technologies to clean up Lake Erie- Federal funding invested in innovative Thames river initiative."

Watch: What causes algae blooms?