Cyanos Activity May 22, 2018
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.
The concentration of Cyanobacteria cells increased compared to those enumerated
from the May 8th samples. Dolichospermum spp. (formerly Anabaena spp.), Woronichinia
spp., Coelosphaerium spp., and Microcystis spp. were observed in the live and preserved
net tow samples during this sampling event. At the North Bay Site, Dolichospermum
spp. was the only genus encountered; that genera was found at a concentration
of 324 cells/mL and 8% of the total planktonic algal community. Uroglenopsis spp.
and Dinobryon spp. of the golden algae taxa collectively comprised 83% of the total
4,031 cells/mL at that site, which suggests that this site’s community is still dominated
by Chrysophytes.
At the Center Lake site, the cyanobacteria were more prominent and comprised 40%
of the planktonic algal community; that group was largely represented by Dolichospermum
spp. However, the golden algae genus Uroglenopsis spp. comprised 46% of the
community. Diatoms collectively accounted for about 12% of the community. Total cell
concentrations at the Center Lake Site was 3,967 cells/mL. These data suggest that
the planktonic community is becoming more productive at the Center Lake site and
that the blue-green algae group is increasing in productivity as well.
Secchi transparency was good; it ranged from 3.42 to 3.56m with a four-site average of
3.50m.
Surface water temperatures on May 21st increased from approximately 16 to 18°C between
May 8th and this sampling event. Surface water temperatures during this
2
sampling event ranged between 15.8 to 16.7°C. However, temperatures at the bottom
(based on sites with >6m depth) increased by approximately 1°C since May 21st
.
Stratification and increased resistance to mix between lake layers contributed to lower
oxygen levels below 5m. Oxygen concentrations >10mg/L from the surface to a depth
of 4m. At depths of 5m, oxygen concentrations were between 7 and 10mg/L. Below
the 5m stratum, oxygen concentrations ranged from 2.6 to 1.3mg/L. This strongly differs
from that observed on May 8th when >8mg/L was observed at the bottom of all
four sites and suggests that benthic microbial activity’s demand for oxygen is surpassing
the refresh rate from the surface due to mixing. Stratification is playing a significant
role in thwarting the redistribution of oxygen from the surface to the bottom; AER
would anticipate that nutrients are loading from the sediments and will continue to do
so as the oxygen concentrations continue to decline.
Data is collected and analyzed by Aquatic Ecosystem Research, who is contracted by Bantam Lake Protective Association.