St. Anthony lock closing after 1/2 a century

[Lee Borgersen]

Upper St. Anthony lock closing after half a century; blame the carp.

How invasive carp harm the river
 

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Healthy Mississippi ecosystemIn a healthy Mississippi ecosystem, young fish and macroinvertebrates live at the bottom of the aquatic food chain. The invasive carp's arrival disrupts the balance. William Lager | MPR News
St. Anthony Falls is the only waterfall on the Mississippi River's 2,300-plus miles from Lake Itasca to the Gulf of Mexico. Invasive carp have been creeping north up the river since the 1970s — and this unique natural barrier has the potential to finally stop its spread. Closing the upper lock to navigation takes away the possibility of carp hitching a ride above the falls alongside river traffic in the lock.

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Scientists are most concerned about the bighead carp, one of three types of the invasive fish threatening U.S. water systems. Once they enter a water system, these carp endanger nearly every level of the food chain, displace native species and alter the balance of the waterway's ecosystem.


How it happens

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These invasive carp are filter feeders, which means they eat the plankton and tiny creatures — macroinvertebrates — at the very bottom of the food chain. All larval and juvenile fish, such as bass, walleye or pike, depend on those tiny creatures for food and can't compete with the more voracious carp.


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[delcecchi]

Took them long enough.