AUBURN — Cornell University ecosystem scientist Dr. Robert Howarth thinks he may have an answer for why harmful algal blooms on the region's lakes last year were so bad, according to a presentation he gave to the Cayuga County Water Quality Management Agency Thursday.
For background, Howarth explained that, until the past decade or so, the academic consensus around harmful algal blooms was that the cyanobacteria they're comprised of formed in lakes with particularly high levels of phosphorous.
However, Howarth said, that wouldn't make sense for Skaneateles, Owasco and Cayuga lakes in 2017. Skaneateles, in particular, has had a phosphorous management program for 32 years, while the other lakes, though higher, were still well below levels presumed to produce harmful blooms.
Recent research suggests that specific ratios of nitrogen to phosphorous allow a different kind of cyanobacteria to form, Howarth said. More than their phosphorous-reliant brethren, this variety produces nitrogen-based toxins that are especially deadly to the zooplankton in lakes that normally limit the bacteria's population.
But why were the blooms so prominent in 2017? According to Howarth's research so far, although he noted it's still new, the severe drought in 2016 allowed nitrogen to build up in the lakes' watersheds before being funneled into the lakes by a much rainier and wet spring and summer in 2017.
As climate change makes such cycles of extreme drought and powerful storms more common, as Howarth suggested, that could result in blooms becoming a more permanent problem, one that would necessitate new solutions.
One aspect that could be controlled, according to Howarth, is the nutrient management of local agriculture. Nitrogen from manure and other fertilizers is a significant contributor to the nitrogen levels within the lakes, along with other sources like sewage, non-agricultural fertilizer use and atmospheric deposition from fossil fuels.
“If this nitrogen idea is correct, and we haven't proven it yet but no one else has come up with a better idea, we need better management strategies,” Howarth said.
Howarth noted that many practices currently in use, such as planting buffer strips of vegetation or using no-till agriculture are only effective for phosphorous management. He suggested the adoption of other practices like winter cover crops or the use of perennial cropping systems to manage both phosphorous and nitrogen.
WQMA member Greg Rejman, of Sunnyside Farms dairy, disagreed with Howarth's assessment that farms in Cayuga County were using excessive amounts of nitrogen-containing fertilizer.
According to Rejman, the county has the highest concentration of farms in the state using injected manure fertilization, which mixes the manure into the soil and helps prevent it dissipating into the air or becoming surface runoff.
Rejman added that any dairy farm over a certain size is classified as a Concentrated Animal Feeding Operation, which comes with restrictions on nutrient management based on guidelines developed by Cornell University.
Howarth, however, said that based on data collected for the county as a whole, local farms were using approximately 20 to 30 percent more fertilizer than necessary even if they were within CAFO guidelines.
Brian Hall, nutrient management specialist with the Cayuga County Soil and Water Conservation District, said after the presentation he was caught off guard by the percentages listed by Howarth. Hall said nutrient management efficiency has greatly increased within the past 20 years, with a particular decrease in supplemental fertilizer thanks to the recycling of manure.
Hall added that Cornell is also currently reevaluating the nitrogen guidelines for its CAFO guidance.
Howarth concluded his presentation to the agency by saying there was still much to be done in terms of algal bloom research, as the phenomenon had caught the academic world "off guard."
Additionally, if his and others' research did bear out that agricultural practices needed improvement, that burden shouldn't fall solely to farmers, he said.
"It's an effort and a cost for farmers to do that so we should be prepared to help them," Howarth said.