A Biologist’s Rationale For Supporting CLP Lake Efforts
¯ It is my long-held view that, while the use of chemicals should be a last resort in controlling various pests or unwanted “nuisance” organisms, e.g., insects, weeds and fungi, there are times when last-resort actions are warranted.
¯ At this point, I am in agreement with the Chautauqua Lake Partnership (CLP) argument that, after years of using only harvesting by the CLA as the sole means of macrophyte (weed) control in Chautauqua Lake, it is time to do a demonstration project in Bemus Bay involving herbicides. Several points are to be made.
¯ Despite having the same or similar names in some cases, the herbicides in common use today are not always the same in terms of formulation and/or application method as those last used in Chautauqua Lake by the CLP in 2002 or by the Chautauqua Lake Association for many years prior to 1989.
Businesses professionally involved in lake management, such as Solitude, retained by the CLP, have experience in using these herbicides and also have a close working relationship with the New York State Department of Environmental Conservation (NYSDEC).
The application methods used by these professionals assure that the chemicals used are applied in the manner intended and at concentrations at or under limits approved for use in New York State for control of the target plant species.
¯ The Town of Ellery and Village of Bemus Point applied for a Bemus Bay herbicide permit targeting treatment as early as May 1, 2017. Early spring application of herbicides is optimal, having the effect of killing the target macrophytes when they are small, thus reducing the amount of new dead and decaying plant material on the lake bottom.
Conversely, waiting to apply the herbicide when the plants are at or near maximum height greatly increases the volume of such decaying plant material, and also increases the amount of nutrients (phosphorus and nitrogen) released into the water during the decay process.
Those released nutrients then become available to living macrophyte and algae populations, including cyanophytes, thus increasing their population growth rates. However, in any case, the early use of herbicides results in greatly reduced volumes of dead plant material deposited on the lake bottom.
¯ Harvesting, the sole means of managing nuisance macrophytes (Potamogeton crispus = curly leaf pondweed, and Myriophyllum spicatum = Eurasian watermilfoil) in Chautauqua Lake since 1988 — with the exception of the use of herbicides in Burtis Bay in 2002, stated above (2a) — is not without its limitations and problems.
¯ Harvesting is time-consuming, labor intensive and costly, and, unlike the application of herbicides, must be done more than once during the summer months for optimum macrophyte control.
That is because the cutters remove only the tops of the plants — up to 6 feet maximum, usually less — and the plants continue to grow because upward plant growth occurs primarily at the apical meristem, i.e. the tip of the plant shoot.
¯ Myriophyllum, a highly branched plant, is capable of producing even more branches during post-cutting growth, analogous to pruning terrestrial shrubs.
¯ Once harvested, the cut plant material must be transported to shore and disposed of in an environmentally approved manner. Not all of the cut vegetation is taken ashore; i.e., some (up to 10% as reported for Chautauqua Lake harvesting operations) remains behind to either float to shore and/or near-shore areas or sink to the lake bottom, becoming subject to decay in both situations and releasing nutrients into the water as previously stated (2b).
Further, in the case of Myriophyllum, the meristematic tips of the uncollected cut vegetation are capable of taking root and growing when in contact with suitable lake bottom sediment. In the case of Potamogetun crispus, the plants produce “winter buds” (turions), which overwinter on the lake bottom and are capable of spring growth into new plants.
Killing the plants with herbicides significantly reduces these harvesting-related problems, including shoreline and lake-bottom deposition, nutrient addition to the water column, annual re-growth, and propagation to previously unaffected parts of the lake.
¯ During the Chautauqua Lake Benchmark Study, a 5-year research program conducted jointly by faculty from SUNY Fredonia and Jamestown Community College from 1972 through 1976,
I was chiefly responsible for all studies of the invertebrate fauna of the lake. During the summer of 1973, I, along with two JCC students, rode the barges onto which the harvested weeds were loaded from the harvester and transported to shore for disposal.
Our task was to collect, identify and record all invertebrates found among the harvested weeds. While engaged in that task, it was apparent to us that small fish of various species were being brought on-board the barge with the cut weeds. We removed those fish and returned them to the lake.
In retrospect, it would have provided good information on the effects of harvesting on fish populations, but we kept no records of the number and species of fish “saved” by our actions. The point is, however, that harvesting does kill a variety of fish and invertebrate animals, and it is important to acknowledge that fact in view of the common concern and argument that herbicides kill aquatic animals, including fish and invertebrates.
With herbicide use, such mortality is minimized when the herbicides are applied as permit conditions require by professional applicators in concentrations recommended by the product label.
¯ Having done some internet research into the use of herbicides on other lakes in various regions of our country, it is clear that the use of herbicides to manage aquatic macrophytes is very common in many states, including New York. Because of the common climatic conditions, I have focused on aquatic herbicide use in northern states, especially Wisconsin, Minnesota and Michigan.
Without citing any such research reports here, the management of the same two species of “nuisance weeds” as are found in Chautauqua Lake is a common occurrence in those states. One notable aspect of using herbicides is the fact that better control of macrophytes is achieved when herbicides are applied early, i.e. in the spring, before the plants achieve much growth.
As previously stated in 2b, this minimizes the amount of decaying plant material on the lake bottom.
¯ Finally, I question why the use of herbicides to manage macrophytes in Chautauqua Lake receives such attention and, in fact, opposition from NYSDEC. According to the CLP consulting firm, Solitude, they are involved in the application of herbicides in many other water bodies in New York State, perhaps as many as 100, and over 500 permits are issued annually by NYSDEC for herbicide applications in New York State water bodies.
Why not Chautauqua Lake? Why are special environmental studies required when herbicides are being considered for use in Chautauqua Lake? Why does the use of herbicides in Chautauqua Lake still fall under a Decision promulgated by then-DEC Commissioner Williams in 1986 and 1987?
Thirty years have passed since those Decisions! Should they not be reviewed for relevance now, in the 21st Century? The recently completed “Chautauqua Lake Macrophyte Management Strategy” includes the use of herbicides as a macrophyte management method, a “tool in the tool box.” Let’s use it!
Thomas A. Erlandson has a PhD in zoology.