Cyanos Activity August 26, 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 Wednesday, August 26th , AER visited Bantam Lake to conduct biweekly Cyanobacteria monitoring. Water column profile data, total depth measurements, 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).
A 500mL composite sample of the top three meters of water column was collected for algae counts at the North Bay and Center Lake Sites using a three-meter long sampling tube. Additionally, a concentrated plankton tow sample, was collected at the Center Lake site using a 10µm mesh net. The concentrated plankton sample was transferred into a 25mL glass amber bottle, stored at 3°C, and preserved with Lugols after an examination with microscopy.
Additional integrated samples were collected from the North Bay and Center Lake Sites by James Fischer, Research Director for the White Memorial Conservation Center, on Friday, August 21st , and by AER on Sunday, August 23rd. The purpose of the additional sample sets was to document Cyanobacteria cell concentrations prior to a copper sulfate treatment which occurred on Monday, August 24th. No other data was collected on August 21st; Secchi disk data was collected for both sites on August 23rd .
The greatest Secchi transparency measurement on August 26th was at the North Bay Site and was measured at 2.27m (Table 1). Secchi transparencies at the Center Lake and Folly Point Sites were 1.98 and 1.88m, respectively. The South Bay Site Secchi transparency was 1.53m, which was similar to the measurements from the North Bay and Center Lake Sites on August 23rd (Fig. 1). On average, Secchi transparency increased by 38cm between August 23rd and August 26th.
Relative concentration of phycocyanin, which is the signature photosynthetic pigment of Cyanobacteria, was measured in situ with a fluorimeter. Measurements from the top three meters of the water column were averaged for each site and presented in Fig. 2. The August 26th site averages exhibited the widest range of relative concentrations with the lowest concentration measured at the North Bay Site and the highest concentration measured at the Center Lake Site. With the exception of the Center Lake Site, the relative concentrations and lake average concentration have generally decreased following both copper sulfate treatments (Fig. 2). The lack of a more pronounced decrease may be related to how copper sulfate acts on the algae cell. The chemical lyses the cells. It is unknown how long the cellular contents, including the phycocyanin remain in the water column.
The August 21st and August 23rd Cyanobacteria cell concentrations for both the North Bay and Center Lake Sites were between 77,849 and 93,522cells/mL (Fig. 3). Cell concentrations decreased precipitously following the August 24th copper sulfate treatment with August 26th cell concentrations measured at 8,447 and 17,736cells/mL at the North Bay and Center Lake Sites, respectively (Fig. 3). The recent cell concentrations and lake average were within the Visual Rank Category 1 range. No public intervention is recommended (CT DPH & CT DEEP 2019).
The Cyanobacteria Dolichospermum spp., Aphanizomenon spp., and Woronichinia spp. were the most abundant algal genera observed. A total of eight different Cyanobacteria genera were observed in the examination of the plankton net sample or in the samples used for counts (Table 2). Several of these genera have been described as having toxigenic properties (CT DPH & CT DEEP 2019, Cheung et.al. 2013, iNaturalist 2019). The total number of genera was 30 with 13 of those being from the Chlorophyta (Green Algae).
Cyanobacteria comprised between 91 and 93% of all cells counted in both samples. The only other taxonomic group with a relative abundance >2% were the Chlorophyta (aka Green Algae) at 4.4 and 4.8% of all cells counted is samples collected from the North Bay and Center Lake Sites, respectively.
Laboratory results from samples collected on August 11th were recently transmitted to AER. Of special interest was the elevated total phosphorus concentrations at the bottom of the water column. At the North Bay and Center Lake Sites, concentrations at the bottom were 102 and 408µg/L, respectively. Concentrations at a depth of 1m (near the surface) were 14µg/L at both sites. The disparity between concentrations at 1m of depth and at the bottom of the water column is a result of internal loading of phosphorus from the lake sediments in the anoxic strata of the water column.
Literature Cited
Cheung MY, S Liang, and J Lee. 2013. Toxin-producing Cyanobacteria in Freshwater: A Review of the Problems, Impact on Drinking Water Safety, and Efforts for Protecting Public Health. Journal of Microbiology (2013) Vol. 51, No. 1, pp. 1–10. See http://www.jlakes.org/ch/web/s12275-013-2549-3.pdf
[CT DPH & CT DEEP] 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
iNaturalist. 2019. Woronichinia. See https://www.inaturalist.org/guide_taxa/700578
Data is collected and analyzed by Aquatic Ecosystem Research who is contracted by Bantam Lake Protective Association.
On Wednesday, August 26th , AER visited Bantam Lake to conduct biweekly Cyanobacteria monitoring. Water column profile data, total depth measurements, 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).
A 500mL composite sample of the top three meters of water column was collected for algae counts at the North Bay and Center Lake Sites using a three-meter long sampling tube. Additionally, a concentrated plankton tow sample, was collected at the Center Lake site using a 10µm mesh net. The concentrated plankton sample was transferred into a 25mL glass amber bottle, stored at 3°C, and preserved with Lugols after an examination with microscopy.
Additional integrated samples were collected from the North Bay and Center Lake Sites by James Fischer, Research Director for the White Memorial Conservation Center, on Friday, August 21st , and by AER on Sunday, August 23rd. The purpose of the additional sample sets was to document Cyanobacteria cell concentrations prior to a copper sulfate treatment which occurred on Monday, August 24th. No other data was collected on August 21st; Secchi disk data was collected for both sites on August 23rd .
The greatest Secchi transparency measurement on August 26th was at the North Bay Site and was measured at 2.27m (Table 1). Secchi transparencies at the Center Lake and Folly Point Sites were 1.98 and 1.88m, respectively. The South Bay Site Secchi transparency was 1.53m, which was similar to the measurements from the North Bay and Center Lake Sites on August 23rd (Fig. 1). On average, Secchi transparency increased by 38cm between August 23rd and August 26th.
Relative concentration of phycocyanin, which is the signature photosynthetic pigment of Cyanobacteria, was measured in situ with a fluorimeter. Measurements from the top three meters of the water column were averaged for each site and presented in Fig. 2. The August 26th site averages exhibited the widest range of relative concentrations with the lowest concentration measured at the North Bay Site and the highest concentration measured at the Center Lake Site. With the exception of the Center Lake Site, the relative concentrations and lake average concentration have generally decreased following both copper sulfate treatments (Fig. 2). The lack of a more pronounced decrease may be related to how copper sulfate acts on the algae cell. The chemical lyses the cells. It is unknown how long the cellular contents, including the phycocyanin remain in the water column.
The August 21st and August 23rd Cyanobacteria cell concentrations for both the North Bay and Center Lake Sites were between 77,849 and 93,522cells/mL (Fig. 3). Cell concentrations decreased precipitously following the August 24th copper sulfate treatment with August 26th cell concentrations measured at 8,447 and 17,736cells/mL at the North Bay and Center Lake Sites, respectively (Fig. 3). The recent cell concentrations and lake average were within the Visual Rank Category 1 range. No public intervention is recommended (CT DPH & CT DEEP 2019).
The Cyanobacteria Dolichospermum spp., Aphanizomenon spp., and Woronichinia spp. were the most abundant algal genera observed. A total of eight different Cyanobacteria genera were observed in the examination of the plankton net sample or in the samples used for counts (Table 2). Several of these genera have been described as having toxigenic properties (CT DPH & CT DEEP 2019, Cheung et.al. 2013, iNaturalist 2019). The total number of genera was 30 with 13 of those being from the Chlorophyta (Green Algae).
Cyanobacteria comprised between 91 and 93% of all cells counted in both samples. The only other taxonomic group with a relative abundance >2% were the Chlorophyta (aka Green Algae) at 4.4 and 4.8% of all cells counted is samples collected from the North Bay and Center Lake Sites, respectively.
Laboratory results from samples collected on August 11th were recently transmitted to AER. Of special interest was the elevated total phosphorus concentrations at the bottom of the water column. At the North Bay and Center Lake Sites, concentrations at the bottom were 102 and 408µg/L, respectively. Concentrations at a depth of 1m (near the surface) were 14µg/L at both sites. The disparity between concentrations at 1m of depth and at the bottom of the water column is a result of internal loading of phosphorus from the lake sediments in the anoxic strata of the water column.
Literature Cited
Cheung MY, S Liang, and J Lee. 2013. Toxin-producing Cyanobacteria in Freshwater: A Review of the Problems, Impact on Drinking Water Safety, and Efforts for Protecting Public Health. Journal of Microbiology (2013) Vol. 51, No. 1, pp. 1–10. See http://www.jlakes.org/ch/web/s12275-013-2549-3.pdf
[CT DPH & CT DEEP] 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
iNaturalist. 2019. Woronichinia. See https://www.inaturalist.org/guide_taxa/700578
Data is collected and analyzed by Aquatic Ecosystem Research who is contracted by Bantam Lake Protective Association.
