Cyanos Activity - April 23, 2020
Water is clean for recreation.
Disclaimer: The information presented below reflects conditions throughout the lake and may differ from conditions on specific shorelines. For information regarding beach closings please contact the Torrington Area Health District or local town officials.
On Thursday, April 23, 2020, AER visited Bantam Lake to conduct biweekly cyanobacteria monitoring and monthly water quality monitoring as part of the ongoing lake management program. Water column profile data and Secchi transparency were only collected from the North Bay Site (N 41.71087° W -73.21155°) due to boat engine concerns.
We were unable to collect those data at the Center Lake Site (N 41.70056° W - 73.22102°), a site west of Folly Point (N 41.70773 W -73.22638), and at a site in the South Bay region of the lake (N 41.69015 W -73.22728) as normally done. We were able to collect from the Center Lake Site a plankton tow sample using a 10µm mesh plankton net. The concentrated plankton sample was transferred into a 25mL glass amber bottle and stored at 3°C. Approximately 500mL of the top three meters of lake water were integrated and collected at both the North Bay and Center Lake sites using a three-meter long sampling tube. These samples were immediately preserved with Lugol’s solution and stored at 3C.
A portion of the phytoplankton net sample was carefully examined with microscopy the same day as collected to identify and list all algal genera prior to any treatment or preservation. Afterwards, the net sample was preserved with Lugol’s solution and stored. Known volumes of the whole water samples from the North Bay and Center Lake sites were treated with hydrostatic pressure to collapse gas vesicles within cyanobacteria cells. Afterwards measured volumes were concentrated with a centrifuge and a vacuum filtration system. Portion of the concentrates were then transferred to a counting chamber. Cells were identified to the genus level and enumerated by counting cells in a randomized portion of the counting chamber with an inverted Nikon Diaphot research microscope at a total magnification of 300X. Cell counts were then corrected to be representative of the whole water samples.
A total of seventeen algal genera were observed in the net tow and concentrated whole water samples. Of those, four were from the golden algae (Chrysophyta) and four from the diatom (Bacillariophyta) taxonomic groups. The cyanobacteria (aka bluegreen algae) and the green algae (Chlorophyta) were both represented by three genera. The algal communities at both sites were dominated by the cyanobacteria, Aphanizomenon spp., which accounted for 87 and 96% of all cells counted at the North Bay and Center Lake sites, respectively.
The cyanobacteria cell concentration at the North Bay Site was 6,912 cells/mL. The concentration at the Center Lake Site was 24,025 cells/mL, or nearly 3.5X greater than that counted at the North Bay Site. The concentration at the North Bay Site was below the intervention threshold of 20,000 cells/mL, and indicative of Visual Rank Category 1. The concentration at the Center Lake Site was greater than the intervention threshold and indicative of Visual Rank Category 2. The State provides guidance on intervention measures (CT DPH & CT DEEP 2019). For Category 2 the following are recommended:
Notify CT DPH and CT DEEP
Increase regular visual surveillance until conditions change
Consider cautionary postings at public access points
Additional information on cyanobacteria is also available at https://portal.ct.gov/DPH/Environmental-Health/Environmental-Health-Section/Blue-Green-Algae-Blooms.
Secchi transparency at the North Bay Site was 2.33m. The water column was mixed with temperatures measured at 8.2°C at 0.5m of depth to 8.1°C at a depth of 6m. The oxygen concentration at 0.5m of depth was 11.2 and decreased to 9.6mg/L at 6m of depth.
Literature Cited
Connecticut Department of Public Health and Connecticut Department of Energy and Environmental Protection. 2019. Guidance to Local Health Departments for Blue–Green Algae Blooms in Recreational Freshwaters. See https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/environmental_health/BEACH/Blue-Green-AlgaeBlooms_June2019_FINAL.pdf?la=en
Data is collected and analyzed by Aquatic Ecosystem Research who is contracted by Bantam Lake Protective Association.
On Thursday, April 23, 2020, AER visited Bantam Lake to conduct biweekly cyanobacteria monitoring and monthly water quality monitoring as part of the ongoing lake management program. Water column profile data and Secchi transparency were only collected from the North Bay Site (N 41.71087° W -73.21155°) due to boat engine concerns.
We were unable to collect those data at the Center Lake Site (N 41.70056° W - 73.22102°), a site west of Folly Point (N 41.70773 W -73.22638), and at a site in the South Bay region of the lake (N 41.69015 W -73.22728) as normally done. We were able to collect from the Center Lake Site a plankton tow sample using a 10µm mesh plankton net. The concentrated plankton sample was transferred into a 25mL glass amber bottle and stored at 3°C. Approximately 500mL of the top three meters of lake water were integrated and collected at both the North Bay and Center Lake sites using a three-meter long sampling tube. These samples were immediately preserved with Lugol’s solution and stored at 3C.
A portion of the phytoplankton net sample was carefully examined with microscopy the same day as collected to identify and list all algal genera prior to any treatment or preservation. Afterwards, the net sample was preserved with Lugol’s solution and stored. Known volumes of the whole water samples from the North Bay and Center Lake sites were treated with hydrostatic pressure to collapse gas vesicles within cyanobacteria cells. Afterwards measured volumes were concentrated with a centrifuge and a vacuum filtration system. Portion of the concentrates were then transferred to a counting chamber. Cells were identified to the genus level and enumerated by counting cells in a randomized portion of the counting chamber with an inverted Nikon Diaphot research microscope at a total magnification of 300X. Cell counts were then corrected to be representative of the whole water samples.
A total of seventeen algal genera were observed in the net tow and concentrated whole water samples. Of those, four were from the golden algae (Chrysophyta) and four from the diatom (Bacillariophyta) taxonomic groups. The cyanobacteria (aka bluegreen algae) and the green algae (Chlorophyta) were both represented by three genera. The algal communities at both sites were dominated by the cyanobacteria, Aphanizomenon spp., which accounted for 87 and 96% of all cells counted at the North Bay and Center Lake sites, respectively.
The cyanobacteria cell concentration at the North Bay Site was 6,912 cells/mL. The concentration at the Center Lake Site was 24,025 cells/mL, or nearly 3.5X greater than that counted at the North Bay Site. The concentration at the North Bay Site was below the intervention threshold of 20,000 cells/mL, and indicative of Visual Rank Category 1. The concentration at the Center Lake Site was greater than the intervention threshold and indicative of Visual Rank Category 2. The State provides guidance on intervention measures (CT DPH & CT DEEP 2019). For Category 2 the following are recommended:
Notify CT DPH and CT DEEP
Increase regular visual surveillance until conditions change
Consider cautionary postings at public access points
Additional information on cyanobacteria is also available at https://portal.ct.gov/DPH/Environmental-Health/Environmental-Health-Section/Blue-Green-Algae-Blooms.
Secchi transparency at the North Bay Site was 2.33m. The water column was mixed with temperatures measured at 8.2°C at 0.5m of depth to 8.1°C at a depth of 6m. The oxygen concentration at 0.5m of depth was 11.2 and decreased to 9.6mg/L at 6m of depth.
Literature Cited
Connecticut Department of Public Health and Connecticut Department of Energy and Environmental Protection. 2019. Guidance to Local Health Departments for Blue–Green Algae Blooms in Recreational Freshwaters. See https://portal.ct.gov/-/media/Departments-and-Agencies/DPH/dph/environmental_health/BEACH/Blue-Green-AlgaeBlooms_June2019_FINAL.pdf?la=en
Data is collected and analyzed by Aquatic Ecosystem Research who is contracted by Bantam Lake Protective Association.
