[Mike]

Fish die-off in Virginia – July, 2007 – algae?
Fish kill cause likely to be algae
Bill Portlock/Chesapeake Bay Foundation

Lab tests show algae bloom caused massive fish kill in Westmoreland

Date published: 7/26/2007
By RUSTY DENNEN

A red-brown algae toxic to fish was the likely cause of a large fish kill July 11 in a Westmoreland County creek.

Lab tests of water samples from Mattox Creek, on the Virginia side of the Potomac River below Colonial Beach, confirmed the presence of karlodinium algae.

“They were a significant component of the [algae] bloom in the Potomac and in the Virginia inlets like Mattox Creek,” Bill Hayden, spokesman for the Virginia Department of Environmental Quality, said yesterday.

Karlodinium are among a group of one-celled organisms that produce red tides and release toxins lethal to fish.

Nearly 300,000 fish, including largemouth bass, white perch, croaker and gizzard shad, washed up along the shore of Mattox Creek. One woman reported dead fish 8 inches deep on her boat ramp.

Biologists took water samples at the creek, which has been at the epicenter of an extended red tide. That extends about 30 miles from Upper Machodoc Creek in King George County, to Sandy Point in Westmoreland County.

“DEQ has been monitoring this about once a week along the Potomac. The bloom we’ve had since mid-June is continuing,” Hayden said.

The densest section is centered near the mouth of Mattox Creek for the past week, he said. “We haven’t had any more reports of dead fish” there.

“We did get a report of a fish kill in the Potomac on July 17,” Hayden said. About 1,000 dead fish were observed.

DEQ didn’t investigate because it was in Maryland waters.

Maryland, too, has been monitoring red tides in the Chesapeake Bay and its tributaries. About 20,000 dead fish were reported on Weems Creek near Annapolis on June 29.

The algae, which can reproduce rapidly during summer months, harm fish in other ways.

Along with producing toxins, when the algae die off in vast numbers, the process consumes oxygen needed by marine life.

Hayden said low levels of dissolved oxygen could have contributed to the Mattox Creek kill.

“That could be a factor, but we haven’t confirmed that yet,” Hayden said.

DEQ took more water samples yesterday.

Algae blooms are common on the Potomac and the Bay in the hot summer months. Nutrients, such as nitrogen and phosphorus, which run into rivers from farm fields, suburban lawns and sewage treatment plants, contribute to their growth.

Rusty Dennen: 540/374-5431
Email: rdennen@freelancestar.com
http://fredericksburg.com/News/FLS/2007/072007/07262007/303201