Original paper

Herbivore-induced saxitoxin production in the freshwater cyanobacterium Lyngbya wollei

Thacker, Robert W.; McLeod, Angela M.; McLeod, Shawn W.


The freshwater cyanobacterium Lyngbya wollei is the dominant primary producer in many lakes and reservoirs in the Southeastern USA. This dominance may be reinforced by the production of chemical defenses, including saxitoxin. Prior research has indicated that saxitoxin production can be induced chemically in the laboratory. We tested whether sympatric herbivorous snails, herbivorous amphipods, and mechanical damage could induce saxitoxin production. We also tested whether water-soluble chemical cues from damaged L. wollei could induce changes in either growth rates or saxitoxin production. Our results indicate that although amphipod herbivory significantly decreased L. wollei growth rates, snail herbivory stimulated strong compensatory growth. Snail herbivory induced higher concentrations of saxitoxin compared to controls, with no significant effects observed from mechanical damage or amphipod herbivory. We observed no significant responses to water-soluble cues from damaged L. wollei. An earlier study demonstrated a trade-off between L. wollei growth rates and saxitoxin production; in contrast, we observed no significant trade-offs between relative growth rates and saxitoxin production. We hypothesize that the relationship between growth and saxitoxin production may depend on the relative supply of nitrogen and phosphorus. The dominance of L. wollei in aquatic communities may be maintained by both induced chemical defenses and strong compensatory growth.


lyngbya wolleicyanobacterial toxinssaxitoxininduced defensechemical ecology