UNTANGLING IMPACTS OF BACTERIAL INTERACTIONS AND CHANGING ENVIRONMENTAL CONDITIONS ON THE GROWTH AND TOXIN PRODUCTION OF PYRODINIUM BAHAMENSE VAR. BAHAMENSE

The dinoflagellate Pyrodinium bahamense forms harmful algal blooms (HABs) in Florida estuaries. This alga produces saxitoxins, which bioaccumulate and negatively impact ecosystems, public health, and local economies. Complex interacting drivers make it difficult to predict Pyrodinium bloom intensity and impacts. For example, increasing ocean temperatures may increase Pyrodinium growth rates and facilitate range expansions. Changing weather patterns, including extreme storms and droughts, cause large salinity swings alongside high summer temperatures, which may accelerate or inhibit bloom formation. Moreover, bacterial interactions influence toxin production in closely related HAB dinoflagellates. It is unknown how climate change will influence interactions in Pyrodinium phycospheres or the downstream effects on blooms. We designed a factorial experiment to test the effects of temperature, salinity, and bacterial interactions on the growth rate, biomass, and toxin production of Pyrodinium. Pyrodinium cultures co-cultured with low- and high-diversity bacterial communities were grown in low (20 PSU), standard (25 PSU), and high salinity (30 PSU) at standard (24ºC) and high temperature (32ºC). Growth is monitored with imaging flow cytometry to detect changes in cell size and morphology alongside growth rates and total biomass. Saxitoxins will be extracted during exponential growth phase and quantified with HPLC. This project will increase our understanding of how marine heatwaves and more frequent extreme weather will influence HAB occurrence and severity in Florida estuaries.

Presentation Preference: Oral

Primary Presenter: Lauren D'Amore, University of South Florida (ldamore715@gmail.com)

Authors:

Lauren D'Amore, University of South Florida  (ldamore715@gmail.com)

Lydia Ruggles, University of South Florida College of Marine Science  (lruggles@usf.edu)

Margaret Mars Brisbin, University of South Florida  (mmarsbrisbin@usf.edu)