[FAIR USE FOR EDUCATION AND RESEARCH ONLY]

Mystery in the marsh

Researchers attempt to find out why Wellfleet's diamondback turtles are dying

By JOHN LEANING STAFF WRITER

WELLFLEET - Two years ago, Don Lewis retired from his post as a senior intelligence analyst with a secret arm of the Defense Department, leaving behind his satellite maps and other tools of the trade. Now his tools are rubber boots and plastic specimen bags, and he's embroiled in an environmental whodunit in his own back yard. As a volunteer with the Massachusetts Audubon Society, Lewis trudges through the Fox Island Wildlife Management area looking for diamondback terrapins, listed as an endangered species in Massachusetts. Since Dec. 7 Lewis has found 66 carcasses, and he and wildlife experts believe that as many as 100 may have died. The diamondback terrapin is in ample supply in other parts of the country, and is still commercially harvested for food in some places. It is considered threatened here because Cape Cod Bay is its northernmost habitat, said Tom French, assistant director of the state Division of Fisheries and Wildlife, and head of the state's Natural Heritage and Endangered Species Program. French rated the Wellfleet die-off a 6 on a scale of 1 to 10 in terms of the Cape's overall diamondback terrapin population, an 8 or 9 for the Wellfleet Bay population. There are believed to be several thousand terrapins on the Cape. Besides the Wellfleet marsh system, they are found around the Great Marsh in West Barnstable, Sandy Neck and areas in Pleasant Bay. The area in Wellfleet that Lewis patrols, and where he has found all 66 dead turtles, is within the state's Fox Island wildlife management area. It is the only diamondback terrapin habitat on the Cape where the deaths are occurring. ---------------

The ooze patrol The marsh is wild and desolate. Grasses are now brown and bent over, hiding tiny rivulets where the turtle carcasses were left by the tides. "The turtles are very difficult to find, almost impossible to the untrained eye," Lewis said as he walked through one area where he's found carcasses in the past. Lewis makes his patrols during low tide, the only time the interior of the marsh and the deeper creeks are accessible. "It's a treacherous terrain. Now that the marsh has thawed, you can fall into pockets. I've literally had to claw myself out," Lewis said, noting that he always brings his cell phone with him, just in case. After the turtle patrols, he returns coated in black, smelly ooze from the marsh. He says his wife bans him from the house until he sheds his fetid clothes. The former National Security Agency official estimates he spends 25 hours a week on the patrols, and another 25 hours working the numbers and locations on his computer. -------------

Deaths began in late autumn Robert Prescott, executive director of the Massachusetts Audubon Society's Wellfleet Bay Wildlife Sanctuary, said, "I wish we had an answer. We just can't seem to figure it out. But a lot of turtles keep popping up in an advanced state of decomposition." The site-specific nature of the turtle deaths tends to eliminate natural causes, French said. If it were weather, there would have been dead turtles all over the marsh system. None of the turtle shells, called carapaces, showed any signs of scratching or gnawing by predators. Working backward from the date the carcasses were first discovered, naturalists believe the turtles died sometime in late October or November, because the carcasses had time to start decomposing before freezing weather arrived. Analysis of the remains is almost impossible because of the advanced decomposition. Lewis spotted a live turtle Oct. 26, which he uses as the last date the turtles were moving before going into the muddy creek bottom to hibernate for the winter. The first dead diamondback appeared Dec. 7. "It's a day that will live in infamy for turtle research," Lewis said, adapting the line from President Franklin D. Roosevelt's address to Congress on Dec. 8, 1941, when the United States declared war on Japan after its Dec. 7 attack on Pearl Harbor. Since then the turtle carcasses have appeared with some regularity in the same areas of the marsh. The numbers peaked March 11, 12 and 13, when Lewis picked up 24 dead turtles. Young, old, male, female, the entire range of the diamondback terrapin population started to become mortality statistics in records Lewis meticulously keeps on his computer. --------------------

Lead suspect: oystermen Prescott said that every year naturalists customarily find a half-dozen or so dead turtles, killed by exposure as ice in the creeks shifts, moving the water channels and uncovering the hibernating turtles. But this was much more than the normal ice kill. Prescott and others think the deaths might have been inadvertently caused by shellfishermen dragging for oysters. The drag could have scraped the hibernating turtles from the bottom, and they could have died from related injuries or exposure. Since the turtles clump together to hibernate, one tow of the drag could do a lot of damage, he said. Prescott and others have no hard evidence, but he does plan to meet with shellfish constable Richard Dickey and the town's shellfish advisory committee to discuss the matter. Proposals could include a ban on dragging in the marsh when the turtles are hibernating. "We don't need to do anything immediately. The best thing is to talk, and see what they think is a solution," Prescott said. French pointed out that the unusually high number of dead turtles has not been seen before. Even without the more intense monitoring Lewis has given the habitat since last July, French said, such high numbers would have been noted in the past. The fatalities, he said, were "probably the result of an unusual activity." "It's a mystery, and that's part of the interest," said Audubon's Prescott. If it is determined that the turtle deaths were caused by human activity, steps can be taken to prevent a recurrence. "But if it's from natural causes, there is not much we can do," Prescott said. "It's a tragedy to find the dead turtles, but if it can help us save the diamondback terrapin species, then it's God's work," Lewis said. Copyright ) 2000 Cape Cod Times. All rights reserved.

http://www.capecodonline.com/cctimes/mysteryin19.htm

-- (Dee360Degree@aol.com), March 19, 2000

Answers

WELLFLEET - Two years ago, Don Lewis retired from his post as a senior intelligence analyst with a secret arm of the Defense Department, leaving behind his satellite maps and other tools of the trade. Now his tools are rubber boots and plastic specimen bags, and he's embroiled in an environmental whodunit in his own back yard.

As a volunteer with the Massachusetts Audubon Society, Lewis trudges through the Fox Island Wildlife Management area looking for diamondback terrapins, listed as an endangered species in Massachusetts.

Since Dec. 7 Lewis has found 66 carcasses, and he and wildlife experts believe that as many as 100 may have died. The diamondback terrapin is in ample supply in other parts of the country, and is still commercially harvested for food in some places.

It is considered threatened here because Cape Cod Bay is its northernmost habitat, said Tom French, assistant director of the state Division of Fisheries and Wildlife, and head of the state's Natural Heritage and Endangered Species Program.

French rated the Wellfleet die-off a 6 on a scale of 1 to 10 in terms of the Cape's overall diamondback terrapin population, an 8 or 9 for the Wellfleet Bay population. There are believed to be several thousand terrapins on the Cape.

Besides the Wellfleet marsh system, they are found around the Great Marsh in West Barnstable, Sandy Neck and areas in Pleasant Bay. The area in Wellfleet that Lewis patrols, and where he has found all 66 dead turtles, is within the state's Fox Island wildlife management area. It is the only diamondback terrapin habitat on the Cape where the deaths are occurring.

---------------

The ooze patrol The marsh is wild and desolate. Grasses are now brown and bent over, hiding tiny rivulets where the turtle carcasses were left by the tides. "The turtles are very difficult to find, almost impossible to the untrained eye," Lewis said as he walked through one area where he's found carcasses in the past.

Lewis makes his patrols during low tide, the only time the interior of the marsh and the deeper creeks are accessible. "It's a treacherous terrain. Now that the marsh has thawed, you can fall into pockets. I've literally had to claw myself out," Lewis said, noting that he always brings his cell phone with him, just in case.

After the turtle patrols, he returns coated in black, smelly ooze from the marsh. He says his wife bans him from the house until he sheds his fetid clothes. The former National Security Agency official estimates he spends 25 hours a week on the patrols, and another 25 hours working the numbers and locations on his computer.

Deaths began in late autumn

Robert Prescott, executive director of the Massachusetts Audubon Society's Wellfleet Bay Wildlife Sanctuary, said, "I wish we had an answer. We just can't seem to figure it out. But a lot of turtles keep popping up in an advanced state of decomposition."

The site-specific nature of the turtle deaths tends to eliminate natural causes, French said. If it were weather, there would have been dead turtles all over the marsh system. None of the turtle shells, called carapaces, showed any signs of scratching or gnawing by predators. Working backward from the date the carcasses were first discovered, naturalists believe the turtles died sometime in late October or November, because the carcasses had time to start decomposing before freezing weather arrived.

Analysis of the remains is almost impossible because of the advanced decomposition. Lewis spotted a live turtle Oct. 26, which he uses as the last date the turtles were moving before going into the muddy creek bottom to hibernate for the winter.

The first dead diamondback appeared Dec. 7. "It's a day that will live in infamy for turtle research," Lewis said, adapting the line from President Franklin D. Roosevelt's address to Congress on Dec. 8, 1941, when the United States declared war on Japan after its Dec. 7 attack on Pearl Harbor. Since then the turtle carcasses have appeared with some regularity in the same areas of the marsh.

The numbers peaked March 11, 12 and 13, when Lewis picked up 24 dead turtles. Young, old, male, female, the entire range of the diamondback terrapin population started to become mortality statistics in records Lewis meticulously keeps on his computer.

--------------------

Lead suspect: oystermen

Prescott said that every year naturalists customarily find a half- dozen or so dead turtles, killed by exposure as ice in the creeks shifts, moving the water channels and uncovering the hibernating turtles. But this was much more than the normal ice kill.

Prescott and others think the deaths might have been inadvertently caused by shellfishermen dragging for oysters. The drag could have scraped the hibernating turtles from the bottom, and they could have died from related injuries or exposure.

Since the turtles clump together to hibernate, one tow of the drag could do a lot of damage, he said. Prescott and others have no hard evidence, but he does plan to meet with shellfish constable Richard Dickey and the town's shellfish advisory committee to discuss the matter. Proposals could include a ban on dragging in the marsh when the turtles are hibernating.

"We don't need to do anything immediately. The best thing is to talk, and see what they think is a solution," Prescott said. French pointed out that the unusually high number of dead turtles has not been seen before. Even without the more intense monitoring Lewis has given the habitat since last July, French said, such high numbers would have been noted in the past.

The fatalities, he said, were "probably the result of an unusual activity." "It's a mystery, and that's part of the interest," said Audubon's Prescott. If it is determined that the turtle deaths were caused by human activity, steps can be taken to prevent a recurrence.

"But if it's from natural causes, there is not much we can do," Prescott said. "It's a tragedy to find the dead turtles, but if it can help us save the diamondback terrapin species, then it's God's work," Lewis said.

-- (Dee360Degree@aol.com), March 19, 2000.