Scientists first found that excessive nitrogen is a major driver of harmful algae blooms growing on Lake Champlain. In this new study, Katelynn Warner was the lead author. These cyanobacteria are known to produce harmful cyanotoxins and the model specifically targeted the Microcystis and Dolichospermum species. Such is the case with this recent research that sheds light on the complicated relationship between nitrogen inputs and algal blooms. Instead, it calls for a comprehensive re-evaluation of the region’s water management strategies.
Led by Dr. Lyman, the study, conducted in 2021, included weekly water sample collections from two important sites—St. Albans Bay and Missisquoi Bay. These findings came as a surprise, showing dramatic differences in nitrogen loads between these areas, with Missisquoi Bay showing much higher concentrations. The past several decades, nitrogen concentrations in the northeast arm of Lake Champlain had been decreasing. Since 2009, independent researchers have measured a massive spike in those levels. Researchers believe that increased flooding is flushing even more nitrogen into the lake’s ecosystem, making the situation even worse.
In this study, they used new-generation, high-frequency buoys with integrated sensors to fully profile the water column every 15 minutes. This new technology provided researchers with the critical ability to observe how rising nitrogen inputs were related to the increasing frequency and severity of algal blooms. The findings have major implications that extend well past fundamental science. Furthermore, they highlight the dangerous lack of implementation of best management practices that are necessary to address nitrogen’s damaging effect on aquatic ecosystems.
Ana “Mindy” Morales, an associate professor at UVM’s Rubenstein School of Environment and Natural Resources, emphasized the importance of recognizing nitrogen’s role in lake ecology.
“We don’t pay as much attention to nitrogen as we need to in water management and lake ecology, and it is very important in determining not always bloom initiation but the composition of the bloom, the toxicity of the bloom, and how long it’s going to last.” – Ana “Mindy” Morales
As for the Microcystis and Dolichospermum species, Warner explained that not all strains of those species are toxic. This variability makes it difficult to assess the toxicity of a bloom.
“You can have strains of those species that have the ability to produce toxins, and other ones that don’t, but you can’t tell the difference just by looking at them.” – Katelynn Warner
The study’s findings upset the widespread assumption that phosphorus is the key nutrient that fuels harmful invasive cyanobacteria blooms.
“When we think about lakes, and we think about production, and what fuels [cyanobacteria], there has been a historical lens that it’s a phosphorus problem. But I think our work shows that it’s more than just that.” – Katelynn Warner
Morales agreed, highlighting the need for a bold, fresh critique of how we manage nitrogen.
“We just need to think more critically about how we manage for nitrogen—because we are not really addressing it.” – Ana “Mindy” Morales