EFFECT OF INCREASING WATER TEMPERATURE ON NON-TOXIN PRODUCING AND TOXIN PRODUCING MIXOTROPHS’ INGESTION RATES

Anthropogenic activity has caused large-scale changes to marine environments such as increasing water temperatures. Previous research has observed that some mixotrophic species increase their heterotrophic activity as temperature increases. However, it is not known if a similar response in heterotrophic activity to temperatures will be observed in toxin producing harmful algal bloom (HAB) mixotrophs. We hypothesized that toxin producing HAB mixotrophs will decrease their toxin production as their ingestion rate increase because previous research has suggested that photosynthesis can be important to toxin production. We measured the ingestion rates of two non-toxin producing mixotrophs (Prorocentrum micans and Heterocapsa steinii) and two toxins producing mixotrophs (Alexandrium monilatum and Karenia brevis) on bacteria under different temperatures using a modified prey removal. Cultures were exposed to three different temperatures for five days and on the sixth day the prey removal experiments were set up and ran for 24 hours. Samples were taken for dinoflagellate abundance, cellular chlorophyll a content, toxin content, and bacteria abundances. Ingestion rates for all species are expected to increase in the higher temperature treatments. Results from this study can help inform managers whether increasing ingestion rates in mixotrophic HABs will decrease the toxicity of the bloom event. Therefore, it can potentially aid in improving our knowledge regarding HAB dynamics in future climate change scenarios.

Presentation Preference: Oral

Primary Presenter: Zabdiel Roldan Ayala, Virginia Institute of Marine Sciences, College of William & Mary (zaroldanayala@vims.edu)

Authors:

Zabdiel Roldan-Ayala, Virginia Institute of Marine Sciences, College of William & Mary  (zaroldanayala@vims.edu)

Nicole Millette, Virginia Institute of Marine Sciences, College of William & Mary  (nmillette@vims.edu)