THE EFFECTS OF TEMPERATURE ON MICROCYSTIN-LR TOXICITY TO BOSMINA LONGIROSTRIS: FOOD WEB IMPLICATIONS IN THE CHOWAN RIVER, NORTH CAROLINA (E)
In the Chowan River, North Carolina, the frequency of Microcystis aeruginosa blooms has increased over recent years along with an average 2.6°C rise in July and August water temperatures since 1975. Zooplankton are an important trophic link for these toxins to move up the food web, but most cannot survive exposure. Bosmina longirostris, a dominant zooplankton in the Chowan River, is resistant to microcystins and consumes toxic cells. This study aimed to understand how microcystin-LR, produced from M. aeruginosa blooms, affects B. longirostris mortality under increasing temperatures. B. longirostris was found to be highly resistant to microcystin-LR, demonstrating an LC₅₀ of 23.3 µg/L. Therefore, B. longirostris can survive current bloom microcystin concentrations ranging 0.26 to 2.0 µg/L. As temperatures were increased from 25°C to 27°C, total mortality increased approximately 30% demonstrating microcystin was more toxic with increasing temperature. Above 27°C, mortality also increased, but this was due to the effect of temperature rather than increased toxicity of microcystin. This signifies that during the spring, when temperatures are below 27°C and B. longirostris is most abundant, microcystin is most toxic and has the greatest influence on the Chowan River food web. Under climate change conditions microcystin may eliminate resistant zooplankton from the food web, putting pressure on larval fish and fisheries.
Jupitz, M. C., East Carolina University, USA, email@example.com
Kimmel, D. G., NMFS, NOAA, USA, firstname.lastname@example.org
Field, E. K., East Carolina University, USA, email@example.com
Location: 323 B
Presentation is given by student: Yes