Tag Archives: Lake Minnewaska

One fish, two fish, small fish, big fish: The recent story of fish in Lake Minnewaska

Big fish eat smaller fish, smaller fish eat zooplankton, zooplankton eat phytoplankton, and phytoplankton produce their own food. If smaller fish eat all of the zooplankton, what’s to stop the phytoplankton from multiplying out of control? If the big fish eat all of the smaller fish, will the big fish still be able to sustain their population? Whenever an organism is added to or taken away from an ecosystem, it acts like a pebble thrown into a pond. There’s the initial splash, then there are ripples that radiate outward affecting everything in their path.

In 2008, a “pebble” was thrown into Lake Minnewaska. This pebble was a type of minnow called a Golden Shiner.  Exactly how the Golden Shiners entered the lake is not certain, however they are a common bait fish so it is  possible that they were introduced to Lake Minnewaska by someone who was hoping to hook the catch of the day! If that was the case, the odds would have been against that fisherman.  For several decades prior to the occurrence of the shiners, there were no fish reported in the lake. Lake Minnewaska has been very acidic in the past, making it an unhospitable environment for most fish to live in. Recently, the pH in the lake has begun to rise to a level closer to neutral, making the lake more inhabitable for fish.

snakes in water
Two Northern Water Snakes compete for a Golden Shiner in Lake Minnewaska. Photo taken by Nicholas Martin, Park Educator, Minnewaska State Park Preserve.

The introduction of a predator to the food web in Lake Minnewaska caused a trophic cascade. A trophic cascade is when a top predator is added to or removed from a food chain. The effects of the addition or loss of this predator are experienced all the way down the food chain. The shiners’ predation on the zooplankton drastically decreased their population. The ripple continued spreading outward because the loss of the zooplankton meant the loss of a major plant consumer. The phytoplankton could then grow and multiply without restraint. The result was an algal bloom in 2011 that turned the lake green and decreased the visibility to less than three feet. As a result, the Minnewaska Swimming Beach was closed for a month that summer.

Minnewaska State Park Preserve
A view of Lake Minnewaska with the Catskills in the background from on top of the quartz conglomerate cliffs surrounding the lake. Photo by John Rozell, OPRHP.

The algal bloom showed us that Lake Minnewaska’s ecosystem had been severely altered by the shiner introduction.   Another ‘pebble’ was tossed in 2012; the “big fish on the block” made its appearance. Largemouth bass entered the lake and filled a role at the top of the food chain.  Bass are avid predators, and they began preying on the shiners.  Electrofishing, the use of a weak electrical current in the water to temporarily stun fish, has been used in the lake every year since the shiners appeared in order to monitor the fish populations. In 2013 there was a large population of 10,000 – 15,000 golden shiners and 700 – 800 largemouth bass in Lake Minnewaska. In 2014 no shiners were observed during electrofishing and the number of bass had increased by 60%. Did the bass population increase because they had an ample food source in the shiners? What will happen to the bass population now that they have lost this food source? We can only wait and see.

signage
It is important not to transport plants or animals from one environment to another. Doing so can start a chain of events that can drastically alter the balance of the ecosystem. Sign by Nicholas Martin, Park Educator, Minnewaska State Park Preserve.

Post by Laura Davis, Park Educator, Student Conservation Association/AmeriCorps Intern, Minnewaska State Park Preserve.

Sources:

Dr. Richardson SRBP Lecture at Suny New Paltz February 2015.

“Baitfish Regulations.” General Regulations. DEC, http://www.dec.ny.gov/outdoor/31416.html. 24 June 2015.

Richardson, David C. “Why Is Minnewaska Lake Turning Green: Changes in Acidity and Fish in the Sky Lakes.” Shawangunk Watch 18 (Summer 2013): 1-3. Print.

Lauren Jorgensen, Kristen Husson, and Karen Terbush. Minnewaska State Park Preserve Lake Minnewaska Water Quality Report. Rep. Albany: NYOPRHP, 2012. Print.

Ecological Change in Lake Minnewaska

Small changes to lake ecosystems can mean big changes for plants and wildlife that make their homes there. Even though Lake Minnewaska (Minnewaska State Park Preserve, Ulster/Sullivan counties) looks the same from above the surface, life in the water has undergone major change in the past several decades. Lake Minnewaska is a unique “sky lake” ecosystem. Historically, Lake Minnewaska has been acidic acidic. No, it wouldn’t burn you to touch it, but it was too harsh for fish to live in. Studies show that Lake Minnewaska was oligotrophic as recently as the 1990s, meaning that nutrient levels were low and the phytoplankton that form algae were absent. The lake was home to other types of creatures, though, including a mat of sphagnum moss which grew up to 20 meters underwater and carpeted 60% of the lake, possible because of the high clarity of the water. The sphagnum moss sheltered two species of salamander which, because of the lack of predators, made use of the habitat and behaved in ways that no one had ever seen elsewhere (Bahret 1996).

Since the ‘90s, however, the lake has gradually become less acidic and phytoplankton more prolific, moving the lake towards mesotrophic status. The primary factor in the trophic shift is the introduction of the non-native bait fish species, the Golden Shiner, which was first observed in Lake Minnewaska in 2008. The Golden Shiner eats zooplankton, which are the primary consumers of phytoplankton, leading an increase in microscopic plant life in the lake. Because of these changes, sphagnum moss no longer grows in Lake Minnewaska, and as these trends continue, we can expect further reductions in water clarity, and more plant and fish species to take up residence in the lake. NYS Parks’ Environmental Management Bureau – Water Quality Unit continues to monitor Lake Minnewaska as an ongoing part of a statewide lake monitoring program.

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References

Bahret, R. 19996. Ecology of lake dwelling Eurycea bislineata in the Shawangunk Mountains, New York. Journal of Herpetology 30:399-401.

Townley, Lauren. Investigation of trophic changes in Lake Minnewaska, a pristine sky lake in Ulster County, New York. Poster, Northeast Association of Environmental Biologists Conference. Online, accessed 8/25/2014.