Dissolved oxygen squeeze poses problems for bay life

WASHINGTON – Usually, putting crabs or fish in hot water leads to one thing: dinner.

But water temperatures in the Chesapeake Bay hit record highs in some spots this week because of the heat wave and that’s causing problems.

“[It] causes what we call the temperature-dissolved oxygen squeeze,” says Bruce Michael, with Maryland’s Department of Natural Resources.

He says the squeeze happens between hot surface water and the oxygen-deprived deeper water. Surface water temperatures climbed to record highs in many spots this week, hitting the low- to mid-80s and stressing many fish.

“It’s probably not going to cause a fish-kill, but it will stress the fish,” Michael says.

The fish become more vulnerable to disease when there’s less oxygen.

Dissolved oxygen is the single most important measure of habitat quality in Chesapeake Bay.

Higher water temperatures can be even worse for underwater grasses since the grasses are stationary. The grasses are where crabs hide from predators.

“These underwater grasses help stabilize the sediment. They produce nutrients. They provide oxygen,” he says.

Dissolved oxygen forces fish and crabs into small areas.

But when fish, crabs and other bay organisms are forced into warmer surface waters, they don’t feed as well as they should. The lack of oxygen also stresses them and impacts their ability to reproduce — something that’s not seen until years down the line.

While area residents can’t control the weather, they can control nitrogen-heavy lawn chemicals, farm fertilizers and urban sprawl that finds its way into the bay and its tributaries.

Residents also can keep current on by conditions and water quality alerts throught Eyes on the Bay.

WTOP’s Max Smith contributed to this report. Follow Max and WTOP on Twitter.

(Copyright 2012 by WTOP. All Rights Reserved.)

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