JoAnn Burkholder

Bio

Over the past ten years, my research has been focused primarily in three areas in aquatic ecosystems:

• Chronic effects of nutrient over-enrichment (eutrophication) and other chemical environmental contaminants (CECs) on aquatic plants (algae, angiosperms)
• The ecology and impacts of harmful algae (cyanobacteria, dinoflagellates, haptophytes, raphidophytes
• Influences of long-term (decadal+) changes in watershed land use and pollution sources on surface water quality

I am the Director of the Center for Applied Aquatic Ecology (CAAE), located in the Department of Plant and Microbial Biology at NCSU. Our research team has designed and maintained a 14-year ongoing research and monitoring program on the Neuse Estuary. We developed and patented an instrument that allows automated depth profiles of water quality on an hourly basis, 24/7, to track environmental changes, examine the ecology of harmful algae, and improve assessment of fish kill causality. We also have designed and maintained a 6-year ongoing research and monitoring program in three major potable water supply reservoirs in North Carolina. We are working to combine our real-time, automated sampling capability with microarrays to detect toxic cyanobacteria (blue-green algae), pesticides and other CECs, and microbial pathogens to improve early warning systems to safeguard public water supplies. We recently completed a decadal study on land use changes in the Neuse watershed, emphasizing the importance of both urban and agricultural pollutant sources. We documented a striking increase in ammonium concentrations, by more than 500%, in surface waters affected by numerous confined swine feed operations. The increased ammonium supply is significantly related to an increase in algal species such as the raphidophyte, Heterosigma akashiwo, that is potentially toxic to humans. In earlier work, we co-discovered potentially toxic estuarine dinoflagellates (Pfiesteria piscicida, P. shumwayae), stimulated by nutrient over-enrichment, than can cause major fish kills. The findings provided the foundation for recent research by toxin chemists at NOAA (Charleston, SC), who described a group of potent Pfiesteria toxins, new to science, with potential application in treating memory disorders.

Area(s) of Expertise

Aquatic ecology and dinoflagellates

Publications

• Watershed Development and Eutrophying Potable Source-Water Reservoirs in a Warming Temperate/Subtropical Region , WATER (2023)
• Classic indicators and diel dissolved oxygen versus trend analysis in assessing eutrophication of potable-water reservoirs , ECOLOGICAL APPLICATIONS (2022)
• Diversity of bioactive compound content across 71 genera of marine, freshwater, and terrestrial cyanobacteria , HARMFUL ALGAE (2021)
• An Environmental Assessment of the North and South Carolina Coasts , WORLD SEAS: AN ENVIRONMENTAL EVALUATION, VOL I: EUROPE, THE AMERICAS AND WEST AFRICA, 2ND EDITION (2019)
• Odorella benthonica gen. & sp. nov. (Pleurocapsales, Cyanobacteria): an odor and prolific toxin producer isolated from a California aqueduct , JOURNAL OF PHYCOLOGY (2019)
• Sampling bias misrepresents the biogeographical significance of constitutive mixotrophs across global oceans , GLOBAL ECOLOGY AND BIOGEOGRAPHY (2019)
• Assessment of atrazine toxicity to the estuarine phytoplankter, Dunaliella tertiolecta (Chlorophyta), under varying nutrient conditions , ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH (2018)
• Chattonella subsalsa (Raphidophyceae) growth and hemolytic activity in response to agriculturally-derived estuarine contaminants , HARMFUL ALGAE (2018)
• Harmful Algal Blooms: a compendium desk reference , (2018)
• Imbalanced nutrient regimes increase Prymnesium parvum resilience to herbicide exposure , Harmful Algae (2018)

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