The Bay is ripe for massive fish kill

By Peter B. Lord, Journal Environment Writer
01:00 AM EDT on Wednesday, August 19, 2009, The Providence Journal

Conditions in Narragansett Bay have reached a perfect storm of high temperatures, low dissolved oxygen and slack tides that could trigger another massive fish kill like the one six years ago in Greenwich Bay.

Few dead fish have appeared this year. And one observer, Narragansett Baykeeper John Torgan, observes that no big schools of young menhaden have entered the Bay yet, so it’s possible a fish kill might not happen.

But as the anniversary of the historic Greenwich Bay fish kill is marked on Thursday, scientists are observing a number of unsettling similarities.

Low oxygen conditions that create dead zones for marine life have spread along the Bay’s bottom from the Seekonk River to Quonset Point in West Passage and Poppasquash Point in East Passage, according to the state Department of Environmental Management’s Bay Assessment & Response Team.

In July, record rainfalls helped stratify the Bay waters, keeping low oxygen water trapped on the bottom while dying marine life continues to consume the remaining oxygen. Water temperatures are now up to 74 to 80 degrees.

Chris Deacutis, chief scientist for the Narragansett Bay Estuary Program, distributed an e-mail to Bay scientists last week warning about the “severe hypoxic” event and the coming neap tide (when the difference between high and low tides is the least) that would provide less energy to mix the Bay waters. He asked for reports of any unusual physical or biological events.

BART warns in its most recent online report that persistent low oxygen “places greater stress on marine life inhabiting the affected waters and increases the vulnerability for potential fish kills.”

Torgan, who monitors the Bay for Save the Bay, warns in a recent blog that conditions in the upper and mid-Bay are particularly bad. Low oxygen conditions are common this time of year as water temperatures rise, he writes, but “this year it appears to be particularly bad, possibly due in part to the record-breaking rainfall in July.”

Torgan said Save the Bay is on “high alert” for reports of fish kills.

The fish kill six years ago was the worst in most peoples’ memories. Dead fish covered the shore as far as you could see, creating an unbelievable stench.

In a followup report, the DEM concluded the fish kill occurred in a summer with an extraordinary number of beach closings due to pollution triggered by rain. The rain brought nutrients into the Bay that triggered blooms of tiny marine animals. Winds and tides and temperatures supported those blooms, which, in turn, triggered low oxygen conditions as the organisms died. Bacteria consuming the dying organisms use up the available oxygen.

Around Greenwich Bay, scientists found many areas with zero oxygen throughout the water column. That’s what killed so much marine life.

A federally funded monitoring collaborative called the Bay Window provided data which helped scientists figure out what happened. Members include researchers from the University of Rhode Island, Brown University, the Narragansett Bay Estuary Program, the DEM’s Division of Fish and Wildlife, the National Oceanic and Atmospheric Administration’s fisheries laboratory in Narragansett and Save the Bay.

Along with millions of menhaden, the lack of oxygen also killed other finfish, eels, crabs and soft shell clams.

Public outrage over the fish killed helped prompt the General Assembly to enact new laws to instill ecosystem-based management for the Bay. Governor Carcieri created the Rhode Island Bays, Rivers and Watersheds Coordination Team to help manage the Bay better.

Deacutis and other volunteer researchers who have dubbed themselves the “Insomniacs” for their round-the-clock sampling efforts continue monitoring the Bay.

Torgan said he went out last Thursday with scientists from Brown and gathered more evidence “that we are experiencing a severe hypoxic event.”

“Conditions are such that a fish kill would not be surprising,” Torgan said Tuesday.

Fortunately, he said, menhaden are not abundant yet in the Bay. Enormous schools have visited during the last few years.

Torgan said fish may have benefited from the poor bottom conditions unfolding slowly, rather than suddenly. That may have left time for many fish to escape.

“Every summer is different,” Torgan said. “We didn’t have low oxygen in July and water temperatures were low then.”