A closeup view of Cayuga Lakes HABs: Citizen scientists pilot test use of inexpensive microscopes for rapid on-site HABs screening
By: Associate Professor Ruth Richardson, Cornell students: Valerie Aubley, Illana Hill, Lydia LaGorga, published in "Cayuga Lake Watershed Network News"
Harmful algal blooms (HABs) have been on the rise in New York State, and Cayuga Lake experienced more blooms than any other NY waterbody in 2020. In fact, 10% of the HABs reported to the NYS DEC statewide in 2020 (94 out of 930) were from Cayuga Lake. Algalblooms are triggered by the presence of excessive nutrients like phosphorus, which spur the growth of the naturally occurring microbe cyanobacteria that congregate into colonies, creating the appearance of “pea soup” at the surface of the water. However, not all algal blooms are classified as HABs: only some types of cyanobacteria produce harmful toxins. This article reports on first steps to developing an inexpensive method for trained volunteers to rapidly determine HABs species and toxicity.
In order to address the growing issue of HABs on Cayuga Lake, the Cayuga Lake Watershed Network (CLWN), Community Science Institute (CSI), and Discover Cayuga Lake worked together to establish the HABs Harriers program, a seminal citizen science program in which community members serve as HABs Harriers who monitor sections of Cayuga Lakeon a weekly basis, checking for and sampling blooms when they occur. The HABs Harriers program has successfully provided three years of data from the resulting HABs samples (2018- 2020), from which some notable trends have emerged.
Key datasets include values measured by the Community Science Institute: chlorophyll A levels (measure of overall bloom level), microcystin toxin levels (MC), and microscopic confirmation of the presence of cyanobacteria. Cyanobacteria are the key toxin producing organisms in freshwater HABs (sometimes called cHABs). Microscopic identification can also be made as to which genera of cyanobacteria are present. By analyzing all cHABs from 2018-2020, itis clear that the high toxin blooms (>4 micrograms per L of microcystin) all have dense colonies of one particular genus: Microcystis.
Some blooms are seen on Cayuga Lake that are dominated by other genera, most notably Dolichospermum. These two types of colonial cyanobacteria have very different features under the microscope. Furthermore, samples of these cyanobacteria can be subjected to biochemical analyses for MC level measurement. However, the biochemical analyses for quantifying MC values requires an accredited laboratory and the use of an analysis called ELISA. These tests are both expensive ($30-$200) and can take up to a day or more to get results.