Environmentalists from around the state have rightly voiced their alarm over the spike in harmful algal blooms (HAB) plaguing freshwater bodies like Lake Hopatcong and Greenwood Lake this summer and called for more aggressive watershed management-based solutions. My 22 years of experience as a scientist working with HABs has given me a perspective on the urgency of what is happening and why solutions need to be enacted now. New Jersey is actually lucky right at the moment ― cyanotoxin levels remain low even though the lakes are filled with high levels of HAB organisms. However, research into the factors that amplify toxin levels in blooms like these suggests that it is only a matter of time before our luck runs out.
The expansion of freshwater cyanobacteria (often called blue-green algae) blooms has been noted for years among researchers. While many recent media reports have focused on the link between nutrients, climate and HAB formation, none have clearly articulated the threat posed by the potent toxins these HABs can produce if and when they start to produce them in excess. The latest measurements by the New Jersey Department of Environmental Protection (NJDEP) show that HABs are occurring without high toxin levels. However, this can change and it is worth noting that the public health crisis presented by a lake full of toxin-producing HABs is far greater than what we are currently seeing, as evidenced by the highly toxic HABs that occurred in Florida’s Lake Okeechobee in the summer of 2018.
The microorganisms that cause these HABs can, under certain conditions, start producing high levels of potent toxins. Think of the HABs as collections of cells – not just different species but also different “strains,” or genetic variants, of the same species. Some strains make cyanotoxins, and others don’t.
For instance, the species Microcytis can produce the toxin microcystin. A lake full of the species Microcystis will include some strains that do not make cyanotoxin and some strains that do. Of course, bigger blooms potentially make more cyanotoxin, but an increase in the ratio of toxic to non-toxic strains can also change overall toxicity. When a lake is dominated by non-toxic strains of Microcystis, then overall cyanotoxin levels (microcystin) are low. When toxic strains dominate, then overall cyanotoxin levels are high.
To date, according to the July 25 NJDEP Lake Hopatcong sampling update, cyanotoxin levels remain below the 3 parts per billion (ppb) New Jersey health advisory level, even though cyanobacterial cell levels are high. By comparison, microcystin cyanotoxin levels in the 2018 Florida blooms exceeded 100 ppb and many people were hospitalized following contact.
Thus, the attention and crisis surrounding New Jersey’s 2019 lake HABs, while very much warranted, is due to the presence of cells without significant levels of cyanotoxin present. What if we had to deal with high cell and cyanotoxin levels in places like Lake Hopatcong and Spruce Run Reservoir?
What turns a less-toxic HAB into a highly toxic HAB? A few highlights from contemporary research conclude that excess nitrogen loading (even in the face of phosphorus controls) appears to favor toxic strains over non-toxic strains of Microcystis. Other experiments in North American lakes found that elevated water temperature, in combination with elevated nutrients, favors accumulation of toxic Microcystis strains over non-toxic strains. Elevated temperature and CO2 levels are likely to favor accumulations of cyanobacteria in lakes over other types of algae. This area of research is continuing and needs investment in New Jersey because understanding the specific conditions that turn our HABs into highly toxic events will inform management and predictive modelling of these events. This research, along with informed citizens anxious to play a role in the science associated with monitoring and prediction, will help us get ahead of this problem instead of repeatedly reacting to events after they occur ”out of nowhere.”
The impacts of humans, including excess nutrient loading to lakes, elevated CO2 levels and rising water temperatures due to climate change, will not only ensure the reoccurrence of these blooms but stack the odds in favor of them becoming toxic and a far more menacing public health threat than what we currently see in New Jersey. Research into these linkages must play an important role in directing actions for solutions.
Jason E. Adolf, PhD
Jason Adolf is an endowed associate professor of marine science with Monmouth University’s Biology Department and Urban Coast Institute. He runs the Phytoplankton and Harmful Algal Bloom research lab (PHABLab) at Monmouth University, where undergraduate students learn phytoplankton research including HABs in various New Jersey environments. Instagram: monmouth_phab_lab.