Increased algal growth is a pervasive problem in lakes around the world. We can group algae into three major groups:
- Floating algae (i.e. phytoplankton) are typically tiny (each made up of just on cell or a few cells) and they float in the water. When abundant, they can give lakes a very green appearance. In the deep waters of Lake George, 40 years of monitoring has demonstrated that we have a very low abundance of floating algae (as expected for such a nutrient-poor lake). However, this low abundance of algae has inceased by about 30% over the past 40 years.
- Macroalgae are very large and often resemble aquatic plants. Examples include filamentous algae and Nitella.
- Attached algae (i.e. periphyton) is the slippery material that grows attached to soil, rocks, logs, and docks. It is actually a combination of algae, fungi, and bacteria that grow on surfaces in the water as well as some sediment that gets trapped in the layer of algae, fungi, and bacteria.
In response to reports by shoreline residents that attached algae seems to be increase around their shorelines over the past several decades, The Jefferson Project reached out to the public for assistance in quantifying the amount of attached algae around the entire shoreline of the lake. We are committed to providing the results of the 2019 Algal Survey to the public (see below).
We were delighted to receive an overwhelming response to help. We selected 50 strategic locations around the shallow waters of the lake, ranging from locations that appear to be relatively pristine to locations that have a large amount of human activity. At each location, we affixed a small clay tile to residents' docks (see photo), approximately 1' below the water's surface. Over time, algae grow on the tiles. Because locations with more nutrients in the water will grow more algae, we can measure the amount of algae on the tile as an indicator of how many nutrients are present in the water.
Each month during the summer, Jefferson Project researchers collected the tiles and replaced them with a new bare tile to grow more periphyton for the next month. The washed-off periphyton was then filtered onto fliter papers (see photo) and dried, allowing us to determine the mass of periphyton growing on each tile. You can see an example of these filters containing periphyton in the photo on the left. In this way, we can quantify differences in algal growth over space and time.