Hans Paerl: Global proliferation of harmful cyanobacterial blooms: What can we do...
Channel: UNC Insitute of Marine Sciences
Date: 02/09/2022

Global proliferation of harmful cyanobacterial blooms: What can we do about controlling it?

Cyanobacterial harmful algal blooms (CyanoHABs) are a major threat to environmental and human health along the freshwater to marine continuum. As global proliferation of CyanoHABs continues to increase in prevalence, intensity, and toxicity, it is important to identify and integrate the underlying causes and controls of blooms in order to develop effective, long-term mitigation strategies. Nutrient input reductions should receive high priority. However, climate changes are driving CyanoHAB proliferation through increasing global temperatures and altered precipitation patterns, including more extreme rainfall events and protracted droughts. Resultant hydrologic extremes have led to the “perfect storm scenario;” due to increases in pulsed nutrient loading events, followed by persistent low-flow, lengthened water residence times, favoring blooms. To meet the CyanoHAB mitigation challenge, watershed and airshed N and P input reductions must be formulated under extreme hydrologic conditions in order to maintain CyanoHABs below bloom thresholds. Specifically, long-term CyanoHAB management strategies must incorporate anticipated climatic changes and extremes, and nutrient management strategies should be compatible with other physical-chemical-biological mitigation approaches, such as altering freshwater flow and flushing, artificial mixing, dredging, chemical applications, and top-down biological controls. Lastly, based on evolving knowledge of environmental controls on cyanotoxin production, these management strategies should find ways to reduce CyanoHAB toxin production, to minimize adverse ecosystem and human health impacts.

UNC Institute of Marine Sciences
September 1, 2022