CLA staff and volunteers are on the hook with some evidence based responses to a few of our most commonly asked questions.
1. Is Eurasian Watermilfoil still a problem plant in Chautauqua Lake?
Once considered an invasive nuisance plant, Eurasian Watermilfoil has become well established throughout the lake in non-nuisance conditions. It is generally no longer densely populated and has been brought under control by the weevil, moth, and caddisfly herbivore insects that feed upon it. It seldom grows to reach the surface like it did years ago. — Racine-Johnson Aquatic Ecologist Report 2019
2. Can Eurasian Watermilfoil and Curly Leaf Pondweed be eliminated from Chautauqua Lake?
Eurasian Watermilfoil and Curly Leaf Pondweed are so prevalent and so intermixed with native plants that the only way to eliminate them would be to also eliminate all plants. The NYSDEC WNY Program for Invasive Species Management lists them as Tier 4 plants. This designates them in a category of not being justified as to what would need to be done to result in elimination. The two plants also play an important role in benefiting the lake’s aquatic life. — https://on.ny.gov/3rTTwcT
3. Is it accurate to say that herbicides are selective to only certain target plants?
Herbicide product labels identify the plants that they target which are generally multiple varieties of plants. Herbicides that are utilized in Chautauqua Lake also affect multiple non-target plants including the important nutrient-absorbing Coontail and fishery-beneficial pondweeds. — Diet for a Small Lake (pgs 155-164)
4. It has been said that while herbicide is selective to certain target plants, that harvesting is not selective.
Both processes affect plants beyond those which are targeted. The two main differences are: Herbicide affects the whole plant, which contributes to the baring of the lake bottom. This makes the lake bottom susceptible to roily water, which releases nutrients from the sediment. Harvesting leaves subsurface plants that stabilize the lake bottom, promoting water clarity and benefiting the lake’s ecosystem. Many varieties of native plants do not grow to a height that is affected by harvesting. — Diet for a Small Lake, pg 154-155, 164
5. Some say that the lake doesn’t really need aquatic plants.
The presence of aquatic plants is critical to the lake’s health and ecosystem. Without plants, algae will likely dominate. The lake will thus have turbid water instead of clear water and it is possible harmful algal blooms will be present. Chautauqua Lake’s world-famous fishery would disappear if there were no aquatic plants. — Scheffer, Nature, October 2001
6. Do all dying plants release nutrients into the water column?
As submerged plants die off, they decompose and release nutrients. Plants that are treated with herbicides go through this process faster, releasing their nutrient content into the water column. Plants that decompose naturally die slower and send most of their nutrients to their root base to provide fuel for the next year’s growth. — Limnology, January 18, 2018, 355-366
7. Is there a connection between herbicide use and algal blooms?
Herbicide use causes the death of living plants. Much of their nutrient content is released to the water instead of into their roots for future growth. Herbicide use can also bare the lake bottom. When a bare lake bottom is disturbed by human or natural activity, the bottom sediments then release their nutrients into the water column. With plants being reduced, algae have more nutrients to consume. Excess algal growth is called a “bloom” and some become harmful. In an already nutrient-rich Chautauqua Lake, additional nutrient sources produced from herbicide use on living plants are available for algal growth. This is the reason herbicide use is not included as a best management practice in the DEC’s Harmful Algal Bloom Actions Plan for Chautauqua Lake. — Aquatic Ecology, 2021, 55:347-361
8. How can I determine if an aquatic plant died naturally or by herbicide?
A simple rule of thumb is plants that have died naturally are usually brown in color, often with some greenness showing, while herbicide treated plants are black in color. — Racine-Johnson Aquatic Ecologist Reports
9. Is it accurate that the predominant summertime nuisance plant that affects navigation is Eurasian Watermilfoil?
The predominant summertime nuisance growing plant is Elodea, a native plant. The only allowed control treatment method for it is harvesting. — Racine-Johnson Aquatic Ecologist Report Spring 2020
10. Does the harvesting process lose volumes of cut plants?
The first machines that were used in the cutting process decades ago did experience a notable loss of cut plants. Machine design has evolved such that the cutting process today results in the cut plants being collected and carried away in the harvesters. Plant loss is minimal. — Racine-Johnson Aquatic Ecologist, 2021 Macrophyte Loss to Chautauqua Lake by Mechanical Harvesting
11. Why do more plants accumulate on my shoreline after harvesting has happened than were there before?
Harvesting opens up surface water flow which then allows for plants that are floating out in the lake to come ashore. — CLA Staff
12. Where do all the floating plants come from?
Floating plants can be caused by boat props, fishing and swimming activities as well as natural die-offs and storm turbulence. These factors often occur before the CLA’s harvesters have even entered the lake for the season. — Racine-Johnson Aquatic Ecologist, 2021 Macrophyte Loss to Chautauqua Lake by Mechanical Harvesting
13. What role can herbicide play in Chautauqua Lake Management?
Herbicide can play an important role should a new invasive plant species arrive that needs to be eradicated. The invasive plant Hydrilla is already close-by in Pennsylvania, at the Erie Canal near Buffalo and near Ithaca. If Hydrilla arrives in Chautauqua Lake, herbicide treatment will be required.
In contrast to the lake’s aquatic plants which are members of the macrophyte community, the invasive Starry Stonewort that has already arrived is a member of the algae community. Herbicide does not work on algae and the use of algicides alone has not been proven to be successful in eliminating Starry Stonewort. Diver Assisted Suction Harvesting (DASH) has proven to be successful, but is very labor intensive and expensive. — https://maisrc.umn.edu/starry-stonewort
14. What is the CLA doing to help in preventing the arrival of new invasive species?
For several years the CLA’s Watercraft Stewards have staffed boat launches on weekends during the summer. Stewards voluntarily inspect arriving and departing boats for the presence of invasive species so that they can be removed. The Stewards also play an important role in educating boaters about invasive species details. Preventing the arrival of invasive species is much less expensive than dealing with them after they have arrived. — CLA Website
15. What are the greatest lake management challenges for Chautauqua Lake?
Contrary to popular belief, managing Eurasian Watermilfoil and Curly Leaf Pondweed does not pose the greatest challenge. Managing the lake’s nutrients poses the greatest challenge due to the algal situation. Next comes dealing with new invasive plants. Starry Stonewort that is already here is topping the list. Every lake management plan has indicated that there will always be a need for plant harvesting in Chautauqua Lake. — Chautauqua Lake Watershed Management Plan, Executive Summary Sept. 2010