Cyanos Activity May 5, 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 Tuesday May 5, 2020, AER visited Bantam Lake to conduct biweekly Cyanobacteria monitoring as part of the ongoing lake management program. Sampling conditions were challenging with strong winds making anchoring difficult. Water column profile and Secchi transparency data were collected from the North Bay Site (N 41.71087° W - 73.21155°) and Center Lake Site (N 41.70056° W -73.22102°).
A plankton tow sample using a 10µm mesh plankton net was collected at the Center Lake site. 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 for algae counts at both the North Bay and Center Lake sites using a three-meter long sampling tube. These samples were preserved with Lugol’s solution shortly after collection and stored at 3C.
A portion of the live phytoplankton net sample was carefully examined with microscopy on the same day it was 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. Measured 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.
Like that observed in late April, a total of seventeen algal genera were observed between the net tow and concentrated whole water samples. The representation of the taxonomic groups exhibited small differences compared to the April 23rd samples. Four genera were from the golden algae (Chrysophyta) and five from the diatom (Bacillariophyta) taxonomic groups. The cyanobacteria (aka blue-green algae) and the green algae (Chlorophyta) were both represented by two and three genera, respectively.
Like on April 23rd, the algal communities at both sites were dominated by the Cyanobacteria, Aphanizomenon spp. (Fig. 1). This genus of Cyanobacteria accounted for 85 and 68% of all cells counted at the North Bay and Center Lake sites, respectively. All Cyanobacteria collectively comprised 85 and 83% of the algal community at the North Bay and Center Lake sites, respectively.
The Cyanobacteria cell concentration at the North Bay Site was 11,914 cells/mL. The concentration at the Center Lake Site was 9,241 cells/mL. Both concentrations were below the intervention threshold of 20,000 cells/mL, and indicative of Visual Rank Category 1 (CT DPH & CT DEEP 2019). Additional information on cyanobacteria is available at https://portal.ct.gov/DPH/Environmental-Health/Environmental-HealthSection/Blue-Green-Algae-Blooms.
The water column at both sites was mixed with temperatures at all depths between 11 and 11.5°C. Oxygen concentrations were >9mg/L throughout. We were not able to obtain temperature and oxygen concentrations at the Center Lake site below 4m due to high winds. Secchi transparencies at the North Bay Site and Center Lake sites were 2.44 and 2.93 meters, respectively.
Data is collected and analyzed by Aquatic Ecosystem Research who is contracted by Bantam Lake Protective Association.
On Tuesday May 5, 2020, AER visited Bantam Lake to conduct biweekly Cyanobacteria monitoring as part of the ongoing lake management program. Sampling conditions were challenging with strong winds making anchoring difficult. Water column profile and Secchi transparency data were collected from the North Bay Site (N 41.71087° W - 73.21155°) and Center Lake Site (N 41.70056° W -73.22102°).
A plankton tow sample using a 10µm mesh plankton net was collected at the Center Lake site. 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 for algae counts at both the North Bay and Center Lake sites using a three-meter long sampling tube. These samples were preserved with Lugol’s solution shortly after collection and stored at 3C.
A portion of the live phytoplankton net sample was carefully examined with microscopy on the same day it was 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. Measured 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.
Like that observed in late April, a total of seventeen algal genera were observed between the net tow and concentrated whole water samples. The representation of the taxonomic groups exhibited small differences compared to the April 23rd samples. Four genera were from the golden algae (Chrysophyta) and five from the diatom (Bacillariophyta) taxonomic groups. The cyanobacteria (aka blue-green algae) and the green algae (Chlorophyta) were both represented by two and three genera, respectively.
Like on April 23rd, the algal communities at both sites were dominated by the Cyanobacteria, Aphanizomenon spp. (Fig. 1). This genus of Cyanobacteria accounted for 85 and 68% of all cells counted at the North Bay and Center Lake sites, respectively. All Cyanobacteria collectively comprised 85 and 83% of the algal community at the North Bay and Center Lake sites, respectively.
The Cyanobacteria cell concentration at the North Bay Site was 11,914 cells/mL. The concentration at the Center Lake Site was 9,241 cells/mL. Both concentrations were below the intervention threshold of 20,000 cells/mL, and indicative of Visual Rank Category 1 (CT DPH & CT DEEP 2019). Additional information on cyanobacteria is available at https://portal.ct.gov/DPH/Environmental-Health/Environmental-HealthSection/Blue-Green-Algae-Blooms.
The water column at both sites was mixed with temperatures at all depths between 11 and 11.5°C. Oxygen concentrations were >9mg/L throughout. We were not able to obtain temperature and oxygen concentrations at the Center Lake site below 4m due to high winds. Secchi transparencies at the North Bay Site and Center Lake sites were 2.44 and 2.93 meters, respectively.
Data is collected and analyzed by Aquatic Ecosystem Research who is contracted by Bantam Lake Protective Association.
