Keynote Address from 2025 Lakes Congress

The attached pdf file is a summary of the key points for the keynote address at the 2025 NH Lakes Congress: The Evolution of Lake Management: What can we learn from the past for a clear future?  The talk covered six decades of lake management, emphasizing the importance of science, economics, and institutions.

Two key take aways included a discussion on internal loading and advances in understanding how cyanobacteria blooms occur.

Internal loading refers to the release of nutrients, particularly phosphorus, from lake sediments back into the water column. When sediments become oxygen-depleted (anoxic), phosphorus that was previously trapped in the bottom sediments is released into the water, essentially recycling nutrients from the lake bottom. Wake boats can significantly affect internal loading of phosphorus in lakes. They produce powerful, downward-directed propeller wash and large wakes that can reach depths of 15 feet (or more in some cases). In shallow areas, this turbulence stirs up bottom sediments, releasing phosphorus trapped in the sediment into the water column. Once phosphorus is in the water column, it becomes available to algae and cyanobacteria, fueling blooms that can degrade water quality and harm aquatic life.

The speaker also illustrated how our understanding of cyanobacteria was advanced by several women limnologists (Caitlin Carey -Dartmouth undergraduate; Holly Ewing from Maine; and Cathy Cottingham (Dartmouth).  Their Key Discoveries showed that:

- Cyanobacteria primarily grow at the sediment-water interface

- They absorb phosphorus directly from the sediment

- Create gas pockets in their cells to float up and form blooms

- Explains why some seemingly clean lakes can suddenly experience algal blooms

Link to summary of talk.

2025 Lakes Congress Keynote Address Summary.pdf

Download PDF • 126KB

Link to YouTube recording of talk.