Fish Kill Reported at Bantam Lake

On Thursday, August 23rd James Fischer and I traveled to the North Bay area of Bantam Lake following reports of dead fish washing up on shore. We walked approximately 75 yards along the edge of North Bay and found several species of dead fish in varying degrees of decay. Most of the dead fish were Sunfish, but we also saw Largemouth Bass, Brown Bullhead, Tench, and White Perch. Since we did not see a large quantity of dead fish, this fish kill was likely due to natural events, such as the record high temperatures we’ve had this summer. When a lake heats up, water holds less oxygen. Therefore during a very hot summer, oxygen levels decline, creating stressful conditions for fish. Also, if shallow waters become too densely occupied by fish, these areas can become more susceptible to disease outbreaks. High levels of turbidity could also be to blame. Turbidity is the haziness of water caused by suspended solids, which can affect the ability of fish gills to absorb oxygen.


A Sunfish that just washed on shore. 
A heavily decayed Largemouth Bass.

 

 
 
 
 
 
Fish kills that are natural and localized are typically no reason for alarm, but tests still should be done to test if levels of toxicity exist. CT DEEP Fisheries Biologist, Ed Machowski concluded that warm water temperature, low oxygen levels, and algae blooms are causing the fish stress. The algae bloom is limiting light penetration, therefore affecting photosynthesis and causing oxygen levels to drop. Dead fish were found at several regions of the lake, but most were found at the North Bay, due to the southwesterly breeze pushing fish to the northeast section of the lake. It should be noted that the fish kill is not related to the August 15th herbicide treatment on selected areas of Bantam Lake.   

Attempts to Manage Phragmites Through "Cut and Drip" Method

Phragmites (Phragmites australis), also known as Common Reed, is an invasive perennial grass commonly found in freshwater wetlands. It often results in dense, monospecific stands, therefore pushing out native vegetation, and altering wildlife habitat. This can negatively impact wildlife that depend on native plants for food and nesting. As of now Phragmites is easy to spot because the reeds are flowering. The terminal flower cluster contains numerous flowers, which together look like long feathery hairs of purple inflorescence. Stands of Phragmites can be found in many wetland locations on White Memorial’s property. For the past three seasons White Memorial has tried to manage Phragmites through herbicide treatment. This management technique first sprays the affected area with herbicide when the Phragmites are in full bloom. After about 2-3 weeks the plants turn yellow and the stalks are mowed to stimulate the growth of other native plants. This technique has been practiced on 30 acres of Phragmites infested areas on the property. The results have yielded some success, but the Phragmites still persistents.


Phragmites stalk with flower.
 
This season we decided to try a different herbicide technique, known as the “cut and drip” method. When using the cut and drip method the larger stalks of Phragmites are cut and then dyed herbicide is dripped into each hollow stem. This is a very meticulous and slow process but does result in a more direct and lethal application of herbicide, which will reduce the likelihood of re-emergence. For now only the large Phragmites are being treated because Phragmites often spreads by its rhizomes. Therefore by treating the larger stalks with herbicide we are also affecting the surrounding, smaller Phragmites as well. So far we have already noticed immediate effects of stands that have been treated. The treated Phragmites have turned yellow and have begun deteriorating. We will have to wait until next season to really understand the long term effects of the cut and drip method and if it stops the regrowth and spread of Phragmites.

Weblog Addition -- Program Calendar of Events

Check out the calendar at the bottom of the page to see what we plan to do each week in the field!

Post-Volant Emergence Count of Bat Colony at the Green Barn

On July 25th a second count of the bat colony in the Green Barn yielded a total of 167 Big Brown bats. The previous bat survey took place May 30th when James Fischer and I counted 127 bats. The May count represents the number of bats before the pups begin to fly (pre-volant) and the July count represents the number of bats after the pups begin flying (post-volant). Therefore, the comparison of this data gives us reliable information about reproduction rate, as well as population growth. It is always a positive sign to see the number of bats increase, although we would have liked to have seen an even higher count, such as in 2010, when 286 bats were counted at the Green Barn. Since White Nose Syndrome is still spreading and devastating bat colonies, the data that is collected is critical in helping researchers measure the fallout of this disease and further explore other possible factors affecting bat population. We have observed that weather conditions greatly affect whether or not bats leave their roost at sunset. On July 18th we attempted to do a post-volant count after a very hot and humid day with late afternoon thunderstorms. We were able to count only 105 bats emerging from the Green Barn and afterwards concluded that the data was inaccurate due to weather. In my opinion, bats will always be a unique and mystifying species. Their imperative role in our ecosystem should always be appreciated and we need to continue to protect these creatures as much as possible.


Two of Gerri Griswold's Big Brown bats.

Recent Edition of the Research and Conservation Forum -- August 2012


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