Abby Webster is a PhD student at SUNY ESF studying benthic and attached cyanobacteria in the Finger Lakes. She works closely with the team at the Finger Lakes Institute in Geneva to conduct her field work, and last summer, deployed artificial substrate racks in Canandaigua Lake to test methods for sampling and monitoring attached cyanobacteria (see the 07/16/2021 CLWA Water Quality Update). Attached cyanobacteria are just that – they are attached to some substrate, which could be rocks, plants, dock legs, buoys, etc. These cyanobacteria are different than those responsible for the harmful algal blooms observed on the surface of Canandaigua Lake each summer, but they are important to study as they are also capable of producing harmful toxins.
In 2021, Abby deployed three artificial substrate racks on the east side of Canandaigua Lake near Cottage City, with permission from CLWA Members Andrea Odenbach, Tom Vecchi, and Sally Napolitano. Each month from June to October, Abby checked on the artificial substrates using a handheld fluorometric tool, the BenthoTorch, to see what algae had attached. The BenthoTorch uses LEDs to measure the relative proportions of the three benthic algal groups: cyanobacteria, diatoms, and green algae. Attached algae are an important component of the base of the food web, and diatoms especially are a high-quality food source for grazers. Below is a graph representing BenthoTorch data from the site in Canandaigua Lake with the most attachment in 2021. Broadly the data show how the attached algal community changed over time. The y-axis is the “Proportion of Total Chlorophyll-a (%)”, and the x-axis displays both depths of the artificial substrate tiles “Surface” and “Bottom”. The four panels in the graph represent each month they were sampled. The blue-green color represents cyanobacteria, the yellow represents diatoms, and the green is for green algae. The size of the different colored bars tells us the proportion of that algal group relative to the total algal biomass. We can infer the following things from this graph: 1) diatoms were the most dominant algal group followed by cyanobacteria, and then green algae, 2) surface and bottom tiles differed only slightly in their attached algal composition, and 3) attached cyanobacteria generally increased in relative proportion to the other algal groups as the summer progressed. It was expected that diatoms would make up the largest proportion of the attached algal groups and that green algae made up the smallest as Canandaigua is a relatively low nutrient lake, and the trend of cyanobacteria makes sense with the warming water temperatures later in the season. Since diatoms are dominant in these assemblages, attached and benthic algae may be a significant source of nutrition for grazers in Canandaigua Lake. Because cyanobacteria are present in these assemblages throughout the season, we want to take a further look into their role as primary producers in Canandaigua Lake and whether they are producing toxins that could enter the food web.
Abby is planning to repeat these methods at two sites in Canandaigua Lake this year. She also plans to SCUBA dive this summer to collect algae growing on the lake bottom for comparison to the tiles while adding light, temperature, and nutrient measurements to help interpret these data. After collecting the algae, she will do microscopy, pigment, nutrient, toxin, and genetic analyses. Abby’s work aims to characterize attached and benthic cyanobacteria communities in the Finger Lakes to better understand their ecology and toxin production. You can contact Abby with any questions you have via email: email@example.com.