Latest Herbivore Report for Chautauqua Lake

Latest Herbivore Report for Chautauqua Lake

A comprehensive report about the diverse communities of herbivores that exist in Chautauqua Lake has recently been released by the Racine-Johnson Aquatic Ecologists. This report details lake observations made in 2022 and findings from 21 years of herbivore monitoring on Chautauqua Lake. 

A few key points taken from this report:

  • “Chautauqua Lake’s herbivory by the weevil and aquatic moth is still an overwhelmingly effective control of the growth of Eurasian watermilfoil, which has been well documented for over 20 years.  The herbivores collectively limit the plant’s elongation toward the lake’s surface, thereby preventing flowering and surface matting by early June.” 

  • “Chautauqua Lake areas treated with herbicides show a much lower occurrence or lack of invertebrate populations. We believe this is primarily due to the loss of habitat.”

  • An increase in herbicide treatment in 2021 is noted as “removing the lush new macrophyte habitat and increasing cyanobacteria growth in the south basin for the summer of 2021, resulting in no invertebrates and no macrophyte habitat in 2022. Protection from the wholesale elimination of plant species from the littoral areas must be a top consideration in the long-term management of the lake.”

  • Locations with the highest densities of weevils and moths in 2022 were:
    • Whitney Bay
    • Dewittville Bay
    • Institution Bell Tower
    • Lighthouse Point 
    • Maple Springs

  • During the last ten years the collection points at the above five locations have been more distant from shore and in deeper water due to decreased or eliminated watermilfoil at close to shore locations.  “we suggest that is due to sustained insect feeding.”  The same has been observed in other lakes.

  • “The Eurasian watermilfoil graph (Figure 13) and the trendline graph for native species (Figure 14) indicate that a “takeover” of the lake plant community is not and should not be a concern for Chautauqua Lake stakeholders.”

  • “Therefore, conserving these essential biological control agents is paramount in maintaining a healthy Chautauqua Lake.  Protection from the wholesale elimination of macrophyte species from the littoral areas must be the top consideration in the long-term management of Chautauqua Lake.  With the loss of macrophytes from a large portion of the south basin, those areas will likely experience a decline of macroinvertebrates, the fishery, water clarity, an increase in cyanobacteria blooms (HABS) and corresponding low oxygen levels in the lake water.  The management decision to prohibit herbicide use north of Long Point in 2019 was astute, and that decision must be reinforced. Prohibiting herbicide use in crucial fish habitats specifically used for spawning and nursery is paramount, as suggested earlier in areas like Tom’s Point, Whitney Bay, and Irwin’s Bay (Luensman et al. 1990)”

The report also details 22 other major scientific findings including records of plant density, herbivore feed rates and the unintended effects of chemical treatments. 

In short, the close monitoring and evaluation of Chautauqua Lake’s ecology is a critical component to lake management. Biological indicators from aquatic plants, mussels, herbivores, HABs as well as the Chautauqua Lake fishery and aviary can provide valuable perspective in the development of a long-term lake management plan.

Related Posts