by Becky Nystrom
This article was first published at chautauquawatershed.org.
If only Chautauqua Lake, an ecological and economic treasure in our midst, could speak. How might we better understand and steward its complex ecosystems upon which so much aquatic life depends, while thoughtfully addressing the ongoing challenges of excessive plant growth, harmful algal blooms, and newly introduced invasive species? The lessons from the lake are knowingly complex and deserve our attention.
We know our lake is an old lake, rich in plant diversity and an abundance of living things. We know its “underwater gardens” are the spawning and nursery beds for bass, muskellunge, bluegill, and sunfish, and the basis for our famous warm water fishery. Nymphs of mayflies, damselflies, and dragonflies crawl among the leaf blades, feasting on tinier insects, while larvae of moths, caddisfly, and weevils forage upon tender buds and feathery foliage. Little things are eaten by bigger things, and all are woven together in an amazing web of interdependency, complexity, and connection. Beyond their importance to the food web, rooted plants release oxygen, stabilize the sediments, and reduce resuspension of silt and nutrients, all significantly improving water quality.
We know the photic zone, where light penetrates the water column, is home not only to obvious lake plants, but also to innumerable tiny green dancers, floaters, and clingers known as phytoplankton, or “algae.” Interestingly, “blue-green algae” aren’t really algae at all, but rather a form of aquatic bacteria known as “cyanobacteria.” In plant-dominated lakes such as Chautauqua, most algae and cyanobacteria are normal residents serving as microscopic oxygenators and food-producers of open waters.
And yet…increased nutrient loading from urbanization of the watershed, erosion, loss of natural shorelines and buffered streambanks, poor lawn-care practices, and warming waters have led to weed-clogged waterways, unhappy humans, and conflicting ideas on solutions. Overgrowths of algae form unsightly and smelly surface scums. More insidiously, harmful algal blooms occur with greater frequency, some producing liver and nervous system toxins dangerous to humans, pets and aquatic creatures alike.
For decades, the Chautauqua Watershed Conservancy has strived to conserve and heal our watersheds to enhance the quality of our local waters over the long term. Our work encourages landowners, municipalities, and others to employ lake-friendly landscaping practices, construct erosion control systems, and install vegetated stream buffers, swales, and rain gardens to intercept pollutants before they flow downstream. We have protected over 1,000 acres of wooded wetlands, streambanks, shorelands, and other natural areas which absorb and filter rainfall and stormwater, reducing downstream nutrient loading and sedimentation which otherwise fuel excessive weed and algae growth in our waterways.
Recent attempts to eradicate the long-naturalized Eurasian watermilfoil and curly-leaf pondweeds via herbicides in Chautauqua Lake have brought clashing viewpoints and confusing messaging. Alarming evidence of harm to our lake’s south basin ecology has caused deep concern and dismay over the apparent collateral damage from the narrowly-informed “quick-fix” chemical approach. Can’t we do better? What lessons may be learned?
Comprehensive scientific research by Robert L. Johnson of Racine-Johnson Aquatic Biologists (2019 Status of Chautauqua Lake’s Aquatic Macrophyte Community Determined by a Lake Summer/Early Fall Survey and Estimates of the Associated Invertebrate Community) warns that the ecological balance of the lake’s lower south basin may now be at risk. We should listen to the science. We hope that the Region 9 State Department of Environmental Conservation (DEC) will listen.
Mr. Johnson is a highly respected scientist who has studied the aquatic plants of Chautauqua Lake, and the tiny insects that consume them, for eighteen consecutive years. His Racine-Johnson Point Intercept-Rake Drag plant sampling method is recognized as the industry standard. His methodology has been endorsed by the NYS DEC and has provided the invaluable long-term data that has guided plant management decisions by the Chautauqua Lake Association (CLA) since 2002. The entirety of his reports and all conclusions are solely the work of Racine-Johnson. He is an award-winning member, former director and past president of the Northeast Aquatic Plant Management Society and is widely recognized for his professional contributions towards improved understanding of the ecology of non-native species Eurasian watermilfoil (Myriophyllum spicatum) and Hydrilla. He has served for many years as an independent third-party scientific herbicide-monitoring consultant for the DEC and other lake associations throughout New York.
Compared to his May 2019 survey and previous years of sampling in the southeast end of Chautauqua Lake, Johnson’s 2019 mid-September survey revealed only barren sediment and unprecedented absence of nearly all aquatic plants. His report warned that these areas were in critical decline likely linked to the 2,4-D and endothall herbicides applied to the 388 south basin acres in May. Reports by seasoned fishermen using marine sonar concurred that nearly all traditional south basin weed lines were lost and replaced with thick algal blooms persisting into late fall.
An earlier and very limited, third-party monitoring report by Princeton-Hydro, contracted by the Chautauqua Lake and Watershed Management Alliance, failed to identify the more widespread, longer-term outcomes documented by Johnson. Its researchers, however, did note that “total biomass…decreased markedly at the treatment sites,” and documented evidence of “potential herbicide drift and resultant reduction in non-target plant biomass” approximately 7-14 days after treatment. Because both herbicides used are known to damage plants many weeks or months after being introduced into the water column, Princeton-Hydro’s one-month study could not possibly capture those longer-term consequences revealed by the Racine-Johnson work.
And while the Princeton-Hydro report did not address algae, the Fall 2019 Racine-Johnson report expressed concern that cyanobacteria and HABs were visually extensive and worsened as one proceeded south, consistent with herbicide application areas. It warned that the wholesale loss of rooted aquatic plants from the littoral zone could push the shallow south basin of Chautauqua Lake from a stable macrophyte-dominated state toward a turbid and undesirable algal-dominated one, with loss of our critical warm water fishery and increased risk of algal scums, cyanobacteria, and toxic HABs.
So much is at stake. There are enough lessons here to justify significant changes in future management decisions for Chautauqua Lake. Let’s listen to the science.
Rebecca Nystrom is a local naturalist and retired JCC Professor of Biology who holds Bachelor’s and Master’s degrees in biology from the University of Buffalo and SUNY Fredonia, respectively. She is a founding director of the Chautauqua Watershed Conservancy, member of the Chautauqua Lake and Watershed Management Alliance Scientific Review and Advisory Committee, and member of the Macrophyte Management Strategy Technical Review Committee.