Persistence of microcystin in three agricultural ponds in Georgia,USA

Authors: SMITH, JACLYN - Oak Ridge Institute For Science And Education (ORISE); WIDMER, ANDREW - University Of Georgia; WOLNY, JENNIFER - Food And Drug Administration(FDA); DUNN, LAUREL - University Of Georgia; Stocker, Matthew; HILL, ROBERT - University Of Maryland; Pisani, Oliva; Coffin, Alisa; Pachepsky, Yakov

Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2024
Publication Date: 11/7/2024
Citation: Smith, J.E., Widmer, A., Wolny, J.L., Dunn, L., Stocker, M.D., Hill, R.L., Pisani, O., Coffin, A.W., Pachepsky, Y.A. 2024. Persistence of microcystin in three agricultural ponds in Georgia,USA. Toxins. 16(11): Article e482. https://doi.org/10.3390/toxins16110482.
DOI: https://doi.org/10.3390/toxins16110482

Interpretive Summary: Microcystin, a toxin produced by harmful algae, is an animal and human health risk in agricultural ponds such as irrigation ponds and livestock watering ponds. Microcystin can be transferred to crops and produced through irrigation practices, and directly ingested by livestock. Currently there are no federal regulations on microcystin in agricultural waters. Two irrigation ponds and one livestock watering pond in Georgia were monitored for microcystin on a monthly basis over a 17-month period to assess how the microcystin concentrations vary through space and time. Our findings indicate that microcystin in agricultural ponds can exhibit large variations across the ponds and throughout the study period. This work can be useful for agricultural pond managers and researchers in that it reveals that microcystin concentration in small agricultural water bodies are not homogenous and that spatial and temporal patterns of microcystin exist.

Technical Abstract: Cyanobacteria and their toxins can have multiple effects on agricultural productivity and water bodies. Cyanotoxins can be transported to nearby crops and fields during irrigation and may pose a risk to animal health through water sources. Spatial and temporal variations of cyanotoxin concentrations have been reported for large freshwater sources such as lakes and reservoirs, but studies on smaller agricultural surface water bodies are lacking. The objective of this research was to determine if spatiotemporal patterns of the cyanotoxin microcystin occur in agricultural waters used for irrigation and livestock watering. The study was performed at two irrigation ponds and one livestock water pond in Georgia, USA, by monthly sampling a fixed spatial grid over a 17-month period. Microcystin concentrations were determined using ELISA microcystin-ADDA kits. Each sampling location was ranked on each sampling date and then ranks were averaged over the entire study. Locations with low (high) average ranks had consistently lower (higher) microcystin concentrations. Results of this work showed that consistent spatiotemporal patterns in cyanotoxins can occur in irrigation and livestock watering ponds which should be accounted for in the development of effective monitoring programs.