Thursday, August 10, 2006
Clam Kill and Low Dissolved Oxygen
The clam die-off and low oxygen conditions that made headlines last week is still going on.
(See http://www.projo.com/news/content/projo_20060805_bay5.1fcb4a8.html , and http://www.projo.com/news/content/projo_20060803_clams3.2008b0e.html).
Although water temperatures have moderated a bit, there is still a vast area of hypoxia in the bottom waters of the Upper Bay. Near-anoxic conditions exist in the cooler, deep dredged channels, and the shallows are still very warm. I was asked to submit a brief article on this whole thing to the national WaterKeeper magazine, and a draft of it follows below.
While I am always cautious about the use of the term "dead zone", Bay conditions are certainly setting up much like they did before the August 19, 2003 "fish kill" in Greenwich Bay. The only missing ingredients are heavy rain and another heat wave. While the bottom waters are in tough shape, huge schools of bluefish from silver dollar-sized juveniles to nine and ten pound slammers are exploding each evening across the Upper Bay. These blues and the juvenile menhaden, anchovies, and silversides they chase are able to tolerate and even thrive on the algae and plankton-rich surface waters.
We'll be out on the Bay in the coming weeks monitoring the conditions, and will continue to push for better science, wastewater capacity and efficiency improvements, and to get rid of cesspools and upgrade failing septic systems. Pollution is definitely a factor in the health of the Bay, and while we can't control the weather (or climate!), we can do more to keep sewage out of the Bay. -JT
Massive Clam Die-Off in Narragansett Bay
In August, after a record heat wave, millions of baby soft-shelled (steamer clams) began washing up on the shores of the Providence River and Narragansett Bay. Extremely high water temperatures (over 80 degrees F) combined with nutrient pollution from wastewater treatment facilities to create a hypoxic “dead zone” that extended throughout much of the Bay.
Narragansett BayKeeper first learned of this through citizen complaints and headed out on the boat to test water quality and survey the scene, accompanied by a reporter and photographer from the Providence Journal. The crew found dead and dying clams knee-deep in some places, along with a heavy stench and clouds of flies. BayKeeper quickly confirmed and documented the hypoxic conditions and high temperatures believed to have caused the kill.
The story ran the following day, prompting regional news coverage and a strong public outcry. Three years prior (August 2003), a similar scene of dead clams washing up preceded a massive fish kill in Narragansett Bay, as over one million juvenile menhaden came up gasping for breath and perished.
“The same conditions that caused the fish kill of ’03 are setting up in the Bay right now,” said BayKeeper John Torgan. “Record heat, excessive nitrogen from wastewater, algae blooms, and other weather and tide conditions are conspiring to suffocate everything on the bottom. We may not be able to control all these factors, but we need to take strong steps now to reduce the pollution. Improving wastewater treatment capacity and removing nitrogen are the best things we can do to prevent this.”