—Olivia Lucia (Mentor: Elizabeth Harvey)
Harmful algal blooms (HABs) pose significant risks to marine ecosystems, coastal economies, and human health due to their ability to produce potent toxins. This study, completed with a Summer Undergraduate Research Fellowship from the Hamel Center for Undergraduate Research, investigates the environmental and molecular drivers of toxin production in the dinoflagellate Alexandrium, a key producer of saxitoxin responsible for paralytic shellfish poisoning. Laboratory cultures grown under controlled temperature and salinity conditions were compared with field samples collected during natural bloom events along the New Hampshire coast. To assess the genetic potential for toxin production, DNA was extracted and screened for the presence of the saxitoxin biosynthesis gene sxtA using PCR, followed by quantification of gene copy number through quantitative PCR (qPCR). Toxin concentrations were measured using enzyme-linked immunosorbent assays (ELISA), allowing for direct comparison between gene abundance and toxin production. Preliminary results reveal substantial variability in both sxtA gene copy number and saxitoxin concentration, with no consistent relationship between genetic potential and measured toxicity. These findings suggest that the presence of toxin-related genes alone is insufficient to predict toxin production and that additional environmental or physiological factors regulate toxicity in Alexandrium. By linking molecular techniques with environmental context, this study contributes to a more mechanistic understanding of harmful algal bloom toxicity and highlights the complexity of predicting toxic events in coastal systems.
