Understanding what drives lake conditions doesn’t happen over a day, a week or even a year.

But what’s known is the fact that many variables are in play – from season changes and precipitation to the surrounding environment – just to name a few.

For Dr. Courtney Wigdahl-Perry, biology professor at SUNY Fredonia, said the presence of algae communities is a key indicator to the health of a lake. Wigdahl-Perry said it’s important to remember that changes seen on lakes, like Chautauqua Lake, are normal since not everything that grows in the lake is present year round. Wigdahl-Perry’s interests are in understanding how environmental change influences organisms that live in lakes.

As a key food source for zooplankton and fish, the presence of algae is pivotal to a lake’s ecosystem.

“There’s one type of algae that blooms in the springtime in diatoms, which do well in low light and cold conditions,” she said. “They love it when the lake turns over in the spring. As ice comes off, the entire lake is mixing. That kicks up nutrients and diatoms love that.”

Shortly after, diatoms absorb the nutrients, but as temperature and light increases, another algae group comes in. Pushing later into the summer emerges blue-green algae, which tend to fair better in warmer conditions. Not all blue-green algae produce harmful toxins, but the ones that do can pose detriments to the lake, she said.

“Often times, the ones that bloom and produce toxins in large amounts grow and make water smell bad,,” she said. “All these changes they create on the lake have an effect on services like recreation, property values or fish populations in terms of recreational fishing. Excessive nutrients coming into the lake is the big culprit.”

Nutrients entering the lake stem from streambank erosion and runoff. Excessive nutrients like phosphorus and nitrogen fuel harmful blue-green algal blooms, which produce a spilled green paint look and a strong odor. Warm temperatures, calm waters and sunlight also drive the blooms.

Overall, Wigdahl-Perry said algae growth is good.

“You want diversity in the algae community. If you didn’t have algae, you wouldn’t have anything else,” she said. “Not all algae are equal. Some come and go. Some of them have effects on the system that we don’t want.”

One aspect that Wigdahl-Perry is interested in finding out on Chautauqua Lake is how and when the water stratifies and mixes. During the summer season in temperate regions, most lakes have a warm surface layer that stays separate from a deep cold layer. The sun heats up the shallow water near the surface, but light and heat do not penetrate to deeper waters.

Wigdahl-Perry said the upper layers are warm enough to stay separate from the colder lower layer because of the density differences between them. This separation, called stratification, can exist for the entire summer.

In the fall when temperatures drop and days become shorter, the surface layer will get cooler, and when cold enough, the whole lake will mix together again.

“Lakes around here will be stratified in the summer, turn over in the fall, and then be stratified again under the ice,” she said. “When the ice comes off the lake in the spring, the whole lake mixes again at spring turnover before setting up in layers again for the summer.”

Stratification can lead to low oxygen in the lower waters during the summer. It can also control changes in nutrient concentrations, which can affect algae growth and the rest of the food web.

“We don’t know much yet about this on Chautauqua Lake. Data collected by people working on the lake suggests that low oxygen may be an issue at some points in the summer, so it’s an important aspect of the lake to study further,” she said

In a few weeks, Wigdahl-Perry will place a buoy on the lake near Point Chautauqua to measure temperature in and out of the lake, pH and algae growth, among other variables. Wigdahl-Perry said the buoy will provide information on the chemistry and the physical changes that occur in the lake.

“(The buoy) has a temperature string on it, so that’ll give us more information on what happens on a day-by-day basis,” she said. “It’s going to take readings every 15 minutes, so it will help us figure out if it does stay stratified all season, if it stays stratified sometime or if it mixes all the time. It’s a pretty powerful tool to understand what’s driving the changes.”

Back in the early days of studying, people thought of lakes as discreet entities. But over the years, Wigdahl-Perry said they’ve learned that there’s more to look at than just the lake.

“You have to think about what’s happening in the watershed, where the water ‘s coming from and what’s the vegetation like on the lake,” she said. Even natural cycles of vegetation can effect water chemistry. We really come to understand that lakes aren’t isolated. They interact with their surroundings.”