@article{lin_torano_whitehouse_pierce_till_hurst_freiberger_mellett_maldonado_guo_et al._2024, title={Variability in the phytoplankton response to upwelling across an iron limitation mosaic within the California current system}, ISSN={["1939-5590"]}, DOI={10.1002/lno.12534}, abstractNote={AbstractCoastal upwelling currents such as the California Current System (CCS) comprise some of the most productive biological systems on the planet. Diatoms dominate these upwelling events in part due to their rapid response to nutrient entrainment. In this region, they may also be limited by the micronutrient iron (Fe), an important trace element primarily involved in photosynthesis and nitrogen assimilation. The mechanisms behind how diatoms physiologically acclimate to the different stages of the upwelling conveyor belt cycle remain largely uncharacterized. Here, we explore their physiological and metatranscriptomic response to the upwelling cycle with respect to the Fe limitation mosaic that exists in the CCS. Subsurface, natural plankton assemblages that would potentially seed surface blooms were examined over wide and narrow shelf regions. The initial biomass and physiological state of the phytoplankton community had a large impact on the overall response to simulated upwelling. Following on‐deck incubations under varying Fe physiological states, our results suggest that diatoms quickly dominated the blooms by “frontloading” nitrogen assimilation genes prior to upwelling. However, diatoms subjected to induced Fe limitation exhibited reductions in carbon and nitrogen uptake and decreasing biomass accumulation. Simultaneously, they exhibited a distinct gene expression response which included increased expression of Fe‐starvation induced proteins and decreased expression of nitrogen assimilation and photosynthesis genes. These findings may have significant implications for upwelling events in future oceans, where changes in ocean conditions are projected to amplify the gradient of Fe limitation in coastal upwelling regions.}, journal={LIMNOLOGY AND OCEANOGRAPHY}, author={Lin, YuanYu and Torano, Olivia and Whitehouse, Logan and Pierce, Emily and Till, Claire P. and Hurst, Matthew and Freiberger, Robert and Mellett, Travis and Maldonado, Maria T. and Guo, Jian and et al.}, year={2024}, month={Feb} }
 @article{pierce_schnetzer_2023, title={Microcystin Concentrations, Partitioning, and Structural Composition during Active Growth and Decline: A Laboratory Study}, volume={15}, ISSN={["2072-6651"]}, url={https://doi.org/10.3390/toxins15120684}, DOI={10.3390/toxins15120684}, abstractNote={Microcystin can be present in variable concentrations, phases (dissolved and particulate), and structural forms (congeners), all which impact the toxicity and persistence of the algal metabolite. Conducting incubation experiments with six bloom assemblages collected from the Chowan River, North Carolina, we assessed microcystin dynamics during active growth and biomass degradation. Upon collection, average particulate and dissolved microcystin ranged between 0.2 and 993 µg L−1 and 0.5 and 3.6 µg L−1, respectively. The presence of congeners MC-LA, -LR, -RR, and -YR was confirmed with MC-RR and MC-LR being the most prevalent. Congener composition shifted over time and varied between dissolved and particulate phases. Particulate microcystin exponentially declined in five of six incubations with an average half-life of 10.2 ± 3.7 days, while dissolved microcystin remained detectable until the end of the incubation trials (up to 100 days). Our findings suggest that concerns about food-web transfer via intracellular toxins seem most warranted within the first few weeks of the bloom peak, while dissolved toxins linger for several months in the aftermath of the event. Also, it was indicated there were differences in congener profiles linked to the sampling method. We believe this study can inform monitoring strategies and aid microcystin-exposure risk assessments for cyanobacterial blooms.}, number={12}, journal={TOXINS}, author={Pierce, Emily F. and Schnetzer, Astrid}, year={2023}, month={Dec} }