Myriophyllum heterophyllum or variable milfoil remains the only known invasive plant in Lake Sunapee. It is also only known to be present in the George’s Mills area, where it was initially found in 2001 (though it had been established there prior to this). Because milfoil species are very difficult to differentiate, particularly with very young plants, LSPA staff has continued to monitor and remove by hand any suspicious milfoil in the area. The benthic barriers (screens placed over the established plants), which were placed in 2001, are also monitored and maintained. Sufficient sediment has accumulated on some of the barrier to support plant growth and native plants seem to be thriving, preventing or retarding the growth of non-native milfoil.
LSPA staff would like to reiterate the importance of Weed Watchers. Early detection of invasive milfoil in George’s Mills is the reason we have been able to contain the spread and control the growth of this species in Lake Sunapee. Other lakes in the state have not been so fortunate. Squam Lake has had multiple applications of aquatic herbicides with less than hoped for results and Lower Suncook Lake had a major application of herbicide in 2004. Suncook’s results look promising after 1 year but the herbicide may not prevent re-growth after 2 or 3 years. The “jury is still out” on Suncook. Lake Masasecum, just south of Newbury, has been regularly “harvesting” (chopping and collecting) milfoil with a specially equipped boat. Masasecum is also the site of one of several ongoing
research projects sponsored by the New Hampshire Department of Environmental Services (NHDES) to control the growth and spread of milfoil.
We continue to keep watch for other invasive plants. In June of 2005 a fragment of Myriophyllum spicatum or Eurasian milfoil was removed from a boat entering the lake at Sunapee Harbor by one of the Lake Hosts (Boat Inspectors). This species is a major problem in Vermont lakes and is in Lake Mascoma (NH), just northwest of Sunapee. About a dozen more species of plants are listed by NHDES as potential invasive plants to watch for. A few of these species, including fanwort, water chestnut, and Brazilian elodea, are established in at least one location in the state.
In general, native aquatic plants in Lake Sunapee seem to be increasing. Since LSPA volunteers and staff have been monitoring for invasive plants, it has been our observation that native plant coverage in the near-shore areas has increased. This is to be expected in the natural aging of a lake. As more sediment accumulates and nutrients levels increase, a better growth environment is provided and plants will take advantage of it.
Very few suspicious plant sightings were reported in 2005 by our volunteer Weed Watchers. All in all, 2005 was a low-key year for invasives in Sunapee (this means a “successful” year). We believe that this was due to our continuing educational efforts, prevention programs including our vigilant Weed Watch Volunteers, and the cooperation of responsible boaters and fisherman.
Other (non-plant) invasive species
Rock bass, a non-native fish considered to be invasive, is already present in Sunapee. But there are other aquatic species to watch for including zebra mussels and rusty crayfish. Zebra mussels are a problem in Lake Champlain and rusty crayfish have spread from their native Ohio/Indiana/Kentucky area to16 more states including all of the New England states except Rhode Island. As with most invasives, these species experience minimal or no predation in their new environments and tend to force out native species.
Algae
Chlorophyll-a is a pigment found in algae in the water column. This pigment can be extracted and quantified from water samples and provide a measurement of overall algae present. Chl-a quantities have not significantly changed over the last several years. But relative numbers of types of algae can and do change over time. The species present and the dominant species vary throughout the season and from year to year.
Based on observation and anecdotal information, there has been an apparent increase in periphyton (algae on rocks and other submerged surfaces). This is probably due to the slowly but steadily increasing phosphorus levels in the water.
The so called “lake balls” (or blobs) are masses of filamentous green and other alga plus organic matter floating in water column. Though they were definitely present in ’05, they did not seem as plentiful as the previous few years.
Though cyanobacteria or blue-green algae has probably “always” been here, occurrence seems to be increasing. Various species have been identified since the mid ‘90s and for the past 2 seasons, Gloeotrichia echinulata has bloomed during the summer. Cyanobacteria, including G. echinulata, produce various toxins that can affect humans and pets though toxin levels have not been at any level of concern.
Date published on web site:
04-01-2006
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