5/14 WEED WATCHING – NH DES PLANT SURVEY OF CANOBIE LAKE
Last fall an intern from NHDES, Angela Piemonte, did a survey of the weeds in Canobie Lake. Her data was compiled and reported on by Amy Smagula (Limnologist/Exotic Species Program Coordinator – NHDES). The only non-native plant identified was purple loosestrife. Although there was an abundance of plant life, it was reported that “This new growth did not seem to be hindering the health of the lake as a whole, and it is a natural process for aquatic plants to expand over time in waterbodies.” The complete report and mapping of identified plant types (19 different ones!) can be found on the CLPA website.
We continue to welcome anyone who would like to become involved in “weed watching” on Canobie Lake. If you do have any weeds or plants of concern please take a picture of them and email the picture to AmySmagula ([email protected] ) and cc to Bill Schroeder([email protected]). It would also be helpful if you took pictures (to share) on a regular basis to document the growth throughout the growing season.
9/14 Why are Weeds Increasing in Canobie Lake?
Long-time residents of Canobie Lake are reporting that there are more weeds in the lake. They report seeing weed beds where there were none in previous years. And weeds seem more dense in the traditional locations. A survey done by DES in August 2013 confirms this. The map from the survey may be seen here: (http://www.canobielake.org/blog/?page_id=490).
In the letter summarizing the plant survey DES states: "Overall, plant abundance in the pond has changed over the last 13 years according to data we have on file. There is an increased abundance of floating pondweed throughout the majority of the shoreline areas." and "This new growth did not seem to be hindering the health of the lake as a whole, and it is a natural process for aquatic plants to expand over time in waterbodies."
We believe the increase in weeds is much more rapid than would happen naturally, and is due primarily to human activity in the lake's watershed. The growth is due primarily to increased nutrients and increased sediment. Here are the leading causes and things we can do about it:
When people fertilize their lawns and gardens, some of the fertilizer runs off into the lake. Green lawns next to the lake are a sure indication that aquatic plants are being fertilized, too. Unfertilized borders of native bushes and groundcover reduce the nutrients reaching the lake.
Another source of excess nutrients reaching the lake is leaking or overloaded septic systems. We recommend having a professional pump your septic system at least every three years, and replace failing systems with new ones.
A third source of excess nutrients is stormwater runoff. In an undisturbed landscape, rain and snow infiltrate into the ground and the nutrients are taken up by the local trees and plants. With human development impervious surfaces replace natural ones and, in many cases, stormwater runs off rapidly into drains and pipes, and is conveyed quickly to the lake. That is why it is so important to direct runoff back into the ground and minimize impervious surfaces, generally.
Stormwater runoff also tends to deposit sediment in our lakes. We've all noticed muck accumulation near the outfall of storm drains. Weeds grow in soil and muck, much more than on the natural rocky bottoms of our lakes.
When we are aware of the things which cause excess weed growth in the lake, we can work together to reduce them and keep our lake beautiful for years to come.
5/16 Got Invasive Aquatic Weeds. Who Ya Gonna Call? Weed Watchers!
As you may know, invasive species are everywhere. They can cause irreparable harm to natural biological systems. Non-native aquatic weeds, once they invade a water body, can permanently alter the environment and usually, not for the better. So far – and unlike nearby Cobbetts Pond, Canobie Lake has been fortunate in that no invasive aquatic weeds have been reported from its waters or shores.
Under the direction of the Canobie Lake Protection Association, a group of locals are aiming to keep Canobie Lake free of invasive species. The local group, nicknamed the Weed Watchers, are in the process of becoming trained to detect and report any invasive aquatic weed they find. With training supplied by Amy Smagula of New Hampshire’s Department of Environmental Services, the band of stalwart Weed Watchers will soon begin their monthly surveys of the shoreline and nearshore for any evidence of invasive aquatic weeds.
The surveys, usually conducted from a boat (canoe, kayak, or motorboat), take each surveyor a couple of hours to complete each month. The aim is to survey the entire shore area of Canobie Lake from May to September for evidence of invasive aquatic weeds. While identifying invasive aquatic weeds can be tricky, the expert training the group is receiving, with follow-up verification by experts for questionable invaders, will insure those nasty plants will be detected in time to prevent an ecological catastrophy. If, and when, an invasive weed is detected, a team from NH-DES will be quick to respond and eliminate the “foreigners” to thwart a successful invasion.
If you are interested in helping out with the survey, please contact Steve Bortone( [email protected] or 813.390.1667). Steve is coordinating the training, which only takes about an hour. Don’t be afraid to participate just because you don’t have a degree in Aquatic Botany. With a little training, patience, and diligence, you too can become an invasive aquatic weed buster.