In addition to European watermilfoil, zebra mussels and blue-green algae, Cazenovia Lake now has a new invasive species in its waters: European Frog-Bit.

According to the 2014 Cazenovia Lake fall plant survey, the European Frog-Bit was discovered on two occasions in the shallow inlet at the north end of the lake during the rake toss survey of the lake’s aquatic plants this fall. The species also was noted to be growing on shore at one side of the public boat ramp in Lakeside Park.

The plant survey, completed by Racine-Johnson Aquatic Ecologists, is done annually to gauge and monitor the health of the lake and the native and non-native plant species found. The survey results were announced by Robert L. Johnson, owner of Racine-Johnson, at the 2014 Cazenovia Lake Summit on Nov. 22.

“The European Frog-bit must be taken seriously. It is not a threat to the deeper areas of the lake because of the wind and waves that would sweep the un-rooted floating plant to the edges. It however could fill the lake surface in the wind protected coves and shoreline areas,” Johnson said. “The plant appears to be in the north-east corner at the inlet, and the extent of its presence should be investigated next year and removed with follow-up surveys planned.”

According to the New York State Department of Environmental Conservation, European Frog-Bit is a free-floating plant that resembles a miniature waterlily. Its leaves are heart-shaped and 1-to-2 inches wide veined on top and dark purplish red with a spongy coating on the underside. The plant has numerous roots up to 12 inches in length that float freely under the plant.

European Frog-Bit populations increase in size rapidly by vegetative reproduction and form dense mats that can limit light penetration into the water, limiting growth of vegetation beneath the mats. In addition, the dense mat of vegetation can also limit the amount of nutrients and dissolved gases reaching native plants beneath the frog-bit mats.

In autumn, as the mats decompose and settle to the bottom of the waterbody, dissolved oxygen levels can be dramatically decreased, resulting in the death of fish and native vegetation. Dense mats of European frog-bit can also inhibit movement of waterfowl, large fish and boats, and limit recreational activities such as swimming. On the other hand, European frog-bit can serve as a food plant for some types of water birds, some fish and insects.

“We are planning to continue our multi-pronged approach to managing Cazenovia Lake and are very pleased to have such excellent scientific guidance,” said Liz Moran, town councilor and president of the Cazenovia Lake Watershed Council. “The discovery of the European Frog-Bit in shallow water reinforces the need for vigilance in preventing the continued introduction of invasive species. This will not affect our management plans; we encourage everyone to learn about the plant and pull it out of the water.”

It is unclear how the European Frog-Bit got into Cazenovia Lake, Village Trustee Fritz Koennecke, who serves on the Lake Watershed Council and as the village commissioner of parks and recreation and oversees the public boat launch at Lakeside Park, told the village board at its Dec. 1 regular monthly meeting.

Koennecke, said that during the winter months he will be reviewing the boat launch and boat inspection protocols to see if there may be a need to revise them, but the species could have been introduced to the lake by various sources not just boats, but by birds, vehicles or fisherman.

“We don’t really have any plan yet for what to do about that. The Lake Watershed Council will have to meet to decide if any action is required,” Koennecke said. “For all we know, it could have been on the other side of the culvert for years. We’ll definitely have to talk about it more in the future.”

At the present time, there are no technologies for the control of European Frog-Bit; hand-harvesting can provide limited, temporary relief, according to the DEC.

Also in the lake plant survey, Racine-Johnson found no evidence of the invasive species hydrilla being in Cazenovia Lake, although they did find that the invasive species European milfoil was present at 255 of the 302 lake locations sampled — or at 84 percent of the locations.

The study also found a new native species, Zannichellia palustris, with the common name of horned pondweed, was at one location in the lake.

Other information discussed during the Cazenovia Lake Summit included updates from both village and town officials on their respective lake-related issues and activities, such as boat inspections and enforcement, stormwater management and mechanical weed harvesting; results of the plant survey and a fish survey and a state DEC report on the state-wide appearances of blue-green algae blooms, which have begun appearing in Cazenovia Lake during the past two years.

All the presentations from the Nov. 22 Cazenovia Lake Summit are now available on the Town of Cazenovia website at townofcazenovia.org, then click on the “Caz Lake Summit Nov. 2014” tab.

Jason Emerson is editor of the Cazenovia Republican. He can be reached at [email protected].