WATCH RELATED VIDEO Submit Algal blooms in the Great Lakes happen because of a one-two punch from the invasive water flea and drain-off from phosphorus fertilizers. A new study says what we can do. Advertisement © 2017 HNGN, All rights reserved. Do not reproduce without permission. Advertisement 0 COMMENTS CLOSE COMMENT Get HNGN's Top Stories Newsletter Everyweek You have already subscribed. Thank you.