Great Lakes Dead Zone
Soon after scientists found that zooplankton in Lake Michigan were forming a seasonal bloom that gave small fish plenty to eat, the bloom started to be replaced with a dead zone devoid of oxygen.
The culprit turned out to be the quagga mussel, an invasive species which is consuming five to seven times as much phytoplankton as is being produced in parts of Lake Michigan, reports Michigan Tech News. Phytoplankton is at the base of the food chain, with small fish and larger fish (such as Atlantic salmon) and fish-eating birds progressively above it.
Consider that the quagga mussels can be found in parts of Lake Michigan in concentrations of 10,000 to 15,000 per square meter, and have ravenous appetites. They eat the Phytoplankton and create lots of mussel poop which in turn helps grow Cladophora algae. The algae die, decompose and remove all the oxygen from the water. Lake animals die without oxygen, and the dead animals kill fish-eating birds through botulism, the often-fatal food poisoning.
People have been worried about what might happen when the Asian carp, with its appetite for plankton, reaches Lake Michigan. The Great Lakes fishery is worth $7 billion annually, reports freep.com. Without plankton, the fish will disappear, so efforts are being made to stop the Asian carp’s advancement. The only problem is that the quagga mussel has beaten the carp to the buffet table.
If you’d like to read more about the quagga mussel, Bayview Compass.com also has an interesting article.