Cross-Species Susceptibility to Harmful Algal Bloom Toxins Microcystin-LR, Anatoxin-a, and Saxitoxin
Citation:
Mattingly, K., M. Jensen-Brickley, A. Banerji, K. Benesh, AND A. Cole. Cross-Species Susceptibility to Harmful Algal Bloom Toxins Microcystin-LR, Anatoxin-a, and Saxitoxin. St. Louis River Summit (UW Superior Yellowjacket Union), Superior, WI, March 03 - 05, 2026.
Impact/Purpose:
Communication of findings regarding new approach methodology for ecotoxicology. Of relevance to aquatic resource managers responsible for public health concerns associated with harmful algal bloom toxins.
Description:
Cyanobacterial blooms, once rare in the St. Louis River estuary, are becoming more common. Bloom-associated toxins (cyanotoxins) may cause deleterious effects in humans, but effects are unknown for many other species. This is due in part to the limited number of species used in toxicology testing. Susceptibility to toxins can also be predicted by comparing target proteins for these toxins—species having functionally different proteins might have different susceptibility to a toxin. To expand our understanding of how common cyanotoxins (microcystin-LR, anatoxin-a, saxitoxin) impact a broad range of organisms, we obtained publicly available data extracted from controlled exposure experiments in the ECOTOXicology Knowledgebase (ECOTOX) and analyzed protein sequences using Sequence Alignment to Predict Across Species Susceptibility (SeqAPASS). ECOTOX provided ample toxicity data for microcystin-LR, whereas anatoxin-a and saxitoxin each have ~one-tenth as many studies (311 publications for microcystin-LR, 32 for anatoxin-a, 28 for saxitoxin). Most studies for microcystin-LR and saxitoxin tested effects in crustaceans and fish, while more than half of anatoxin-a studies focused on algae and plants. A subset of the species with studies in ECOTOX also had protein sequences available for SeqAPASS analysis. Susceptibility predictions from SeqAPASS tended to be corroborated by ECOTOX findings. SeqAPASS predictions were also available for hundreds of unstudied species per toxin and could help inform future work. Most species received “susceptible” predictions. Fungi were often classified as nonsusceptible to microcystin-LR, a finding that aligns with proposals to use fungi for bloom remediation. For anatoxin-a, we found evidence that invertebrates may be less susceptible than vertebrates, because invertebrates lack the protein variants that have been shown to bind strongly with anatoxin-a. Our efforts to predict which organisms might be differentially affected by toxic blooms will ultimately inform larger-scale estimates of blooms’ impacts on whole aquatic communities, in the St. Louis River estuary and beyond.