LONG-TERM PERSPECTIVE ON HARMFUL ALGAL BLOOMS FROM UTAH LAKE

Harmful Algal Blooms (HABs) are a widespread phenomenon in marine and freshwater ecosystems. Cyanobacteria, a photosynthetic aquatic microorganism, are the primary component of HABs and cause adverse effects on human and ecosystem health through the production of toxins. Despite the wide diversity of algae species attributed to HABs, many respond to similar abiotic factors, including light, temperature, turbidity, and nutrient availability. In recent decades, there has been a global increase in cyanobacterial biomass that has been attributed to anthropogenic climate change and nutrient loading. Freshwater sedimentary archives provide an opportunity to explore past event with isotope analysis of δ15N, a tool for exploring the historical occurrence of HABs and their ecological impacts on freshwater ecosystems. Enrichment of δ15N in macroalgae has been correlated with anthropogenic sources of nitrogen run-off, and studies indicate that enrichment of δ15 in macroalgae is a function of distance decay from anthropogenic nitrogen sources. Despite these findings, limited research has examined potential linkages between changes in δ15N and historical HABs from long-term sedimentary archives. Paleoecological research on sedimentary records collected from Utah Lake provide insight into this phenomenon and further our understanding of δ15N as a proxy for historical HABs. As anthropogenic climate change is predicted to generate favorable conditions for more HABs in the future, it has become increasingly important to understand their causes and consequences.