New Threat to NH Lakes Is Just a Duck Flight Away
By ROGER TALBOT

Sunday News Staff
The Union Leader

Hydrilla verticillata is a bully of a weed that may soon shoulder its way into a pond or lake in your neighborhood. So resilient and aggressive is this aquatic plant, a native of Africa and Asia, that even the dreaded milfoil is a shrinking violet in comparison. Where hydrilla grows, the water-based economy staggers - and the weed has surfaced in Maine, just 15 miles shy of New Hampshire's border.
    
Thus far, no hydrilla has been found in New Hampshire, but 15 miles is a frighteningly short travel distance for a plant that can migrate in the belly of a duck, hitch a ride on a boat trailer, bait bucket or drag line, or be dumped in a pond by a careless fish lover.
     
Those who keep fish in aquariums decorate with hydrilla because the weed - known in the pet trade as anacharis - transfers oxygen to the water and because its tendrils, which can grow an inch a day, add vibrant greenery.

CResearchers suspect hydrilla introduced to a canal near Miami and into the Crystal River near Tampa more than 40 years ago was probably brought to Florida as an aquarium plant. Hydrilla has been branded a "noxious weed" by the federal government and its sale or transport in New Hampshire is illegal. The discovery of hydrilla in 46-acre Pickerel Pond, in Limerick, Maine, has Jody N. Connor's attention.

Because of building restrictions, and conservation efforts, it's now one of the most undeveloped and cleanest lakes in New Hampshire. Homes and land are at a premium, and even at that, they're a rare commodity. Few owners are willing to part with their precious memories.

The Florida experience
"I'm really scared of hydrilla. I lived with it in Florida and I've seen what it can do," said Connor, limnologist at the state Department of Environmental Services. Connor was in Florida in the 1970s, studying for his master's. "It had taken over many of their lakes," he recalled. "They have had to close off some lakes. They can't use them anymore because it grows so thick you can't row a boat through it."

Florida has spent millions of dollars in a vain effort to control hydrilla. "I thought it wasn't going to get this far north, but a few years ago it was found in Connecticut (two ponds near Mystic), and then in Massachusetts two years ago (in Barnstable on the Cape), and now in Maine," Connor said of hydrilla.

Biologist Amy Smagula, exotic species program coordinator at the DES, went to Limerick two weeks ago to photograph the hydrilla in Pickerel Pond and gather samples for laboratory analysis. Last week, the pond was treated with fluridone, a herbicide that kills the plant but is generally viewed as only a temporary fix.

"What we saw was 6-to-8 inches long and scrawny looking, but it has the potential to grow very large," Smagula said of the hydrilla in Pickerel Pond. Hydrilla has small leaves, with saw-toothed edges. The leaves are arranged in whorls of four-to-eight along slender stems (1/32-inch thick) that can rise as much as 25 feet above the muck in which the plant's tuber is rooted.

On the lookout
Smagula said biologists do not know how hydrilla got to Pickerel Pond. It could have been a boater, or someone discarding the aquatic greenery from a fish tank, or birds. Geese and ducks transit the pond. Hydrilla's passage through the digestive system of waterfowl that eat it does not diminish the ability of the plant and its potato-like tuber to reproduce.

Though hydrilla is close, Smagula and Connor have hope it can be kept out of New Hampshire's waters. They're distributing photos and educating weed watchers, lake hosts, boaters and fishermen, with particular emphasis on the lakes and ponds in the Ossipee-Wakefield area, some of which straddle the Maine-New Hampshire border.

"For the past 30 years, we've been pushing milfoil heavily (it has infested 55 lakes and ponds), but with hydrilla we have an opportunity to get ahead of it, as opposed to managing it. We really want to prevent this," Smagula said.

Early Detection Key
"We have a chance of prevention," Smagula said of the boat inspections done by the state's network of "lake hosts." And, if hydrilla does creep in, "we have a chance at early detection, which makes all the difference," she said.

There are about 350 trained volunteer weed watchers who patrol the state's waters looking for nascent infestations. There are about 200 lake hosts, backed this year by grants of $187,000 raised through a $3 surcharge on boat registration fees. They look for suspect vegetation when boats are put in or taken out of the water. Last year, the first for the hosts, they stopped milfoil from getting into five lakes, include Newfound, one of the state's largest, and Nubanusit in Nelson, the state's clearest. But hydrilla is a formidable foe.

"It is very serious," said Connor. " Hydrilla is probably going to be one of the state's biggest problems as far as exotics that can take over lakes and ponds."

Researcher Kenneth A. Langeland, of the University of Florida's Institute of Food and Agricultural Sciences, dubbed hydrilla the "perfect aquatic weed" in a paper he wrote in 1996. At that time, hydrilla had spread to 43 percent of the public lakes in Florida, to all the Gulf Coast states, up the East Coast as far as Delaware, and to California, Washington and Arizona. It is known to be able to overwinter in temperatures as cold as those along the U.S.-Canadian border.

Economic Impact
Hydrilla can impede water flow, clog intakes and flood canals. It can interfere with commercial and recreational boating, discourage swimmers, displace native vegetation and fish populations. "The economic impact of these water uses to real estate values, tourism and user groups can be staggering," Langeland wrote. He cited the case of Florida's Orange Lake, which lost an estimated $11 million in economic activity when it was overgrown by hydrilla.

Langeland described hydrilla as "a couple of steps ahead" of its competition. On the bottom, it starts out requiring less sunlight than other submersed plants. When it gets to the surface, it branches profusely, its mat-like entanglement intercepting the sunlight its rivals need to grow. Connor said hydrilla, if it invades New Hampshire, could easily solve the milfoil problem. He noted milfoil isn't much of a problem in Florida, where hydrilla is king.

Langeland wrote of hydrilla's reproductive efficiency. It can reproduce from a turion, the fleshy shoot that develops at the leaf axil; from a turion or bud on the tuber, the plant's underground stem; from a seed and from a fragment. A turion can survive for four years in undisturbed sediment and produce more than 6,000 new turions. A fragment with as few as a single whorl of leaves can sprout a new plant.

Methods of attack
Herbicides and mechanized harvesters can be used to control hydrilla, but Connor considers the chemicals little more than temporary "Band-Aids," while giving the weed "a haircut" usually results in a thicker, tougher regrowth.

Langeland wrote of the extensive research done in the past 20 years on hydrilla's natural enemies - snails, a weevil from Pakistan, an aquatic moth, 40 assorted insects and manatees. They all like to eat hydrilla, but each has its drawbacks.

The grass carp, for example, devours hydrilla, but that fish is banned from New Hampshire. "They eat everything in the water body," Smagula said of the grass carp's gluttony. "They would eat the native vegetation and then stir up the bottom so much that you would end up with a murky-looking pond."

In the end, the best defense may be to educate water users about the weed. "I think there is a good chance that eventually we'll get hydrilla, but we've got some good on-going programs," Connor said of his lake hosts and weed watchers. "If it does show up and we can identify it and get there quick and pull it out before it starts spreading, that is the best chance we have to stop it," he said.

Reprinted With Permission of
The Union Leader