Cyanos Activity June 19
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 06/19/2019 AER visited Bantam Lake to conduct biweekly cyanobacteria and water quality monitoring as part of the ongoing lake management program. Water column profile and Secchi transparency data were collected from the North Bay Site (N 41.71087° W -73.21155°), 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).
Samples collected for algal identifications and enumerations were from the North Bay, Center Lake, and South Bay sites. We report on the former two here. A plankton net tow sample, using a 10µm mesh plankton net, was collected at the Center Lake site. Samples were treated, stored and analyzed following methods discussed in previous memos.
Secchi transparencies at the four sites were good, however, the average was 2.98m was 1.3m less than that observed on June 4th . June 19th Secchi transparencies ranged from 3.00 to 3.12m at North Bay, Center Lake, and Folly Point sites; transparency at the South Bay site was 2.75m.
A total of 24 algal genera were observed between the net tow sample and integrated water samples. Cyanobacteria and green algae (Chlorophyta) were the most diverse taxa with 6 and 7 representative genera, respectively. Five genera of golden algae (Chrysophyta) were also identified.
Cyanobacteria cell concentrations increased by an order of magnitude compared to June 4th but were still well below concentrations that warrant intervention for public health concerns (CT DPH 2019). At the North Bay site, most of the 4,113cells/mL of cyanobacteria were Aphanothece spp. or Aphanocapsa spp. Cell sizes for both genera were <3µm in diameter. At Center Lake, where the cyanobacteria cell concentration was 3,345 cells/mL, Aphanizomenon spp. and Dolichospermum spp. were also signifi- 2 cant community constituents. Those two genera are often the cause of bloom conditions at Bantam Lake. Increases in concentrations of those genera will be watched closely.
A species of Dinophyceae, Ceratium hirundinella, was uncommonly high but accounted for <1% of the pelagic algae community at both sites. Concentrations of 24 and 30cells/mL were calculated in the North Bay and Center Lake sites, respectively. However, unlike the Aphanothece spp. and Aphanocapsa spp. Ceratium hirundinella cells are very large; the genus is one of the largest flagellated unicellular algae in freshwater. Cells in Bantam exceeded 175µm in length (Fig. 1).
Surface water temperatures continued to climb and were approximately 2°C warmer than those measured on June 4th . Most of the water column was mixed with only the very 0.5 to 1m separated from the rest of the water column at the North Bay, Center Lake, and South Bay sites due to temperature / density gradients. There bottom water oxygen concentrations were ≤0.5mg/L. At the South Bay site where the shallower water column was mixed, oxygen concentrations at the bottom were 5.4mg/L.
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://www.ct.gov/deep/lib/deep/water/water_quality_management/monitoringpubs/bluegreenalgaeblooms_guidanceforrlhds.pdf.pdf
Data is collected and analyzed by Aquatic Ecosystem Research, who is contracted by Bantam Lake Protective Association.
On 06/19/2019 AER visited Bantam Lake to conduct biweekly cyanobacteria and water quality monitoring as part of the ongoing lake management program. Water column profile and Secchi transparency data were collected from the North Bay Site (N 41.71087° W -73.21155°), 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).
Samples collected for algal identifications and enumerations were from the North Bay, Center Lake, and South Bay sites. We report on the former two here. A plankton net tow sample, using a 10µm mesh plankton net, was collected at the Center Lake site. Samples were treated, stored and analyzed following methods discussed in previous memos.
Secchi transparencies at the four sites were good, however, the average was 2.98m was 1.3m less than that observed on June 4th . June 19th Secchi transparencies ranged from 3.00 to 3.12m at North Bay, Center Lake, and Folly Point sites; transparency at the South Bay site was 2.75m.
A total of 24 algal genera were observed between the net tow sample and integrated water samples. Cyanobacteria and green algae (Chlorophyta) were the most diverse taxa with 6 and 7 representative genera, respectively. Five genera of golden algae (Chrysophyta) were also identified.
Cyanobacteria cell concentrations increased by an order of magnitude compared to June 4th but were still well below concentrations that warrant intervention for public health concerns (CT DPH 2019). At the North Bay site, most of the 4,113cells/mL of cyanobacteria were Aphanothece spp. or Aphanocapsa spp. Cell sizes for both genera were <3µm in diameter. At Center Lake, where the cyanobacteria cell concentration was 3,345 cells/mL, Aphanizomenon spp. and Dolichospermum spp. were also signifi- 2 cant community constituents. Those two genera are often the cause of bloom conditions at Bantam Lake. Increases in concentrations of those genera will be watched closely.
A species of Dinophyceae, Ceratium hirundinella, was uncommonly high but accounted for <1% of the pelagic algae community at both sites. Concentrations of 24 and 30cells/mL were calculated in the North Bay and Center Lake sites, respectively. However, unlike the Aphanothece spp. and Aphanocapsa spp. Ceratium hirundinella cells are very large; the genus is one of the largest flagellated unicellular algae in freshwater. Cells in Bantam exceeded 175µm in length (Fig. 1).
Surface water temperatures continued to climb and were approximately 2°C warmer than those measured on June 4th . Most of the water column was mixed with only the very 0.5 to 1m separated from the rest of the water column at the North Bay, Center Lake, and South Bay sites due to temperature / density gradients. There bottom water oxygen concentrations were ≤0.5mg/L. At the South Bay site where the shallower water column was mixed, oxygen concentrations at the bottom were 5.4mg/L.
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://www.ct.gov/deep/lib/deep/water/water_quality_management/monitoringpubs/bluegreenalgaeblooms_guidanceforrlhds.pdf.pdf
Data is collected and analyzed by Aquatic Ecosystem Research, who is contracted by Bantam Lake Protective Association.
