Flies don't lie; Dragonflies, caddisflies and other insects and wildlife are signs of healthy waterways.
COLUMN: THE WORLD AROUND US
Michael F. Veit recalls the day he was trying to enjoy nature while sitting by a pond in New Hampshire, but having a difficult time of it because of unending harassment from biting deer flies.
To his pleasant surprise, a dragonfly appeared and began picking off the nasty deer flies. What happened next led to the biology teacher's continuing enchantment with odonates, an order of insects that includes dragonflies and their relatives, damselflies.
The dragonfly munching on the deer flies was suddenly swallowed up by another dragonfly, a huge one, Mr. Veit said, that seemed to come out of nowhere.
"I told myself I have to learn more about this," he said.
Dragonflies, with their gemstone-colored bodies, fairylike wings and cute faces, have lots of enthusiasts. And with good reason. Besides their physical attributes, odonates feed on flies and mosquitoes - but they don't bite or sting. (That old story about them sewing up lips is untrue.)
Certain species can also serve as indicators of the environmental health of rivers and streams.
Mr. Veit, an entomologist who is the chairman of the science department at Lawrence Academy in Groton, acknowledged that their name is kind of scary. It's even worse in Ecuador, where the name translates to "rides on the back of the devil," he said.
Female dragonflies and damselflies deposit their eggs into rivers, streams, ponds, bogs and vernal pools. Larvae, sometimes called nymphs, subsequently emerge as squat, brown insects that develop in water before transforming, like butterflies, into the more beautiful adult specimen. They can spend from a few weeks to two or three years in the larval stage before shedding their skins.
David H. Small, president of the Athol-based Bird and Nature Club, has conducted several dragonfly studies, both in the Millers River valley and other watersheds around the state.
"These nymph skins are an excellent conservation tool," Mr. Small said. "Through them, you can find a lot out about water bodies they are in."
The numbers of dragonfly skins found can indicate how the water has affected that particular species.
"There is a lot of interest in water quality and this helps assess the health of the water bodies," Mr. Small said. "We are looking at them as an indicator species, a canary-in-the-coal-mine sort of thing."
There are hundreds of species of dragonflies and damselflies, he said, but certain rare ones - including the arrow clubtail, zebra clubtail and brook snaketail - indicate good quality water.
Mr. Small said all three types have been found in the Millers River watershed, which encompasses 17 towns near Athol in North Central Massachusetts and Southern New Hampshire.
Like the Nashua River, in Central Massachusetts, the Millers River has improved from a
polluted state caused by decades of industrialization. Cleanups began in the 1970s with passage of the federal Clean Water Act.
"The dragonflies, along with trout and other insects and wildlife that use the river, are indicators that it's come back, and it's not compromised," Mr. Small said.
In fact, looking for dragonflies and damselflies is so popular in the Millers River watershed that a "NymphFest" is held at the Millers River Environmental Center in Athol each year. The event attracts researchers, scientists and enthusiasts from all over the country.
There are other wildlife indicators of good river health, according to Mary H. Marro, an environmental educator at the Nashua River Watershed Association in Groton.
The glamorous dragonfly, she said, takes second place to a few not-so-pretty fly larvae, namely, caddisflies, mayflies and stoneflies.
"Those are the real indicators of clear, clean water," Ms. Marro said. Dragonflies and damselflies, she said, are found in moderately clean water. Mr. Veit said that while some dragonfly species prefer clean, unpolluted water, others tolerate poor conditions.
Ms. Marro, who regularly takes student groups to rivers, ponds and streams to scoop pails of water and look for insects and other creatures to help determine water quality, said it is mainly the water's oxygen content that makes it a good habitat for choosy insects. Charts showing diagrams of the creatures, which include crawfish and snails, are used. They are grouped into three categories of typical invertebrates found in good, fair, and "any" water.
She said area waters in which she and her students have found those insects are smaller, colder tributaries such as the Squannacook River near Townsend, parts of the Monoosnoc Brook in Leominster, the Nissitissit River in Pepperell, and the Whitman River in Westminster.
"The Nashua River is fair. Basically, the smaller streams and tributaries near mountains - in Ashby, Princeton, Ashburnham - start off clean, but as they flow downstream they pick up fertilizer, trash and pesticides," Ms. Marro said.
Edward D. Himlan, director of the Leominster-based Massachusetts Watershed Coalition, contends that the presence of coldwater trout is one of the best signs that a river is in good shape.
"Trout is a really good indication of high water quality," he said.
But he explained that fish need a diverse insect population to feed on, so finding caddisflies, mayflies and dragonflies, along with various other insects, goes hand-in-hand with good water quality.
"If you find a lot of one kind of insect, one that is tolerant of water pollution, then that means the river is not in such good shape," he said.
Mr. Himlan said he has seen coldwater trout in the Stillwater River in Sterling and the Quinapoxet River in Holden. The Monoosnoc, he said, while still slightly impaired from city pollution, has lots of caddisflies.
The pond at Leominster State Forest, Mr. Himlan said, has very few insects, probably because of the acidic soil in and around it. Sometimes, he said, roads that cross over streams and ponds cause sand and silt to filter into the water, changing its composition.
"That limits habitat, and diversity," Mr. Himlan said. "Mayflies and caddisflies need pore space, and sand fills that in."
Rona L. Balco, president of the Friends of the Oxbow National Wildlife Refuge in Harvard and a retired teacher, said freshwater mussels are another sign of good river health.
"Mussels are bottom feeders, and if they can get nutrients out of bottom, then that's a good sign." Toxins and pollutants, she said, are found way below the bottom, too far for mussels to get to.
Like Mr. Veit, Mrs. Balco has witnessed dragonflies snapping up other insects, and even frog eggs.
"The larvae that hatch in the water are very hungry. They eat a lot of stuff," she said.
Mrs. Balco agreed that caddisflies and some dragonflies and damselflies "are all sure signs of a very successful pond," and that parts of the Nashua River have them, along with what she described as a "mussel highway" in the river's bed.
"A lot of insects and a lot of fish tell you it's in good shape. Otters are another good sign, along with turtles and snakes who come to feed on insects," she said.
"It's all one big buffet," Ms. Balco said with a laugh.
Contact Karen Nugent by e-mail at email@example.com.
ART: PHOTOS; ILLUSTRATION
CUTLINE: (1) Ray Morales, his 10-year-old daughter, Tatiana, center, and Sabrina Ramos, 11, look for insects scooped from the bottom of the Nashua River in Groton. Students at the Northwest School in Leominster, the girls attended a river classroom presented by the Nashua River Watershed Association. (2) Nashua River Watershed Association river guide Nancy Ohringer leads a river classroom on the banks of the Nashua River in Groton for students from Leominster's Northwest School. (ILLUSTRATION) Nashua River Watershed aquatic invertebrates
PHOTOG: (PHOTOS) T&G Staff/RICK CINCLAIR (ILLUSTRATION) T&G Staff/TOM HUNT
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|Title Annotation:||LOCAL NEWS|
|Publication:||Telegram & Gazette (Worcester, MA)|
|Date:||May 22, 2008|
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