Widespread, low concentration microcystin detection in a subtropical Louisiana estuary

• Published in: Marine pollution bulletin Vol. 207; p. 116843
• Main Authors: Jaegge, Andrea C., Lavergne, Bryce C., Stauffer, Beth A.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-10-2024
• Subjects: Cyanotoxins; Environmental Monitoring - methods; Estuaries; Estuary; Louisiana; Microcystins; Microcystins - analysis; Solid phase adsorption toxin tracking (SPATT); Water Pollutants, Chemical - analysis; Louisiana; Solid phase adsorption toxin tracking (SPATT); Estuary; Cyanotoxins; Microcystins
• ISSN: 0025-326X; 1879-3363; 1879-3363
• DOI: 10.1016/j.marpolbul.2024.116843

Spatiotemporal patterns and drivers of hepatotoxic microcystins (MC) were investigated in the Atchafalaya-Vermilion Bay System (AVBS), a subtropical, river-dominated estuary in Louisiana. Along with environmental data, monthly particulate MC (pMC) samples were examined over a two-year period (2016–2018), and biweekly pMC and dissolved MC (dMC) samples were examined over a five-month period in 2020. Solid phase adsorption toxin tracking (SPATT) samplers used to quantify time-integrated dMC concentrations were also deployed in 2020. Low, but detectable concentrations of pMC (≤0.033 μg L−1) and dMC (≤0.190 μg L−1) were found throughout the AVBS in 37.8 and 21.2 % of samples, respectively. Time integrative SPATT samplers detected dMC in nearly 100 % of the deployments, compared to dMC detections in 30.8 % of the discrete samples. This study documents widespread MC presence throughout the AVBS and while concentrations were low, knowledge gaps remain regarding the potential long-term impacts of sublethal MC exposure to estuarine organisms.
•Low microcystin concentrations were detected throughout a river-influenced estuary.•Biogeochemical cycling and physical forcing explained variability in toxin dynamics.•Interactions within phytoplankton communities were also explanatory factors.•Dissolved microcystins were more frequently detected in SPATT than discrete samples.•Sublethal but prolonged cyanotoxin exposure to organisms may be of concern in this system.