High and Low Iron Upwelling and Corresponding Shifts in the Diatom Community
College of Sciences
Diatoms are unicellular phytoplankton known for an ability to respond quickly to nutrient pulses, allowing them to bloom in upwelling environments, potentially leading to high sedimentation rates after a bloom. Understanding the effect upwelling has on the diatom community is vital, as climate predictions indicate that upwelling events will become stronger, less frequent, and longer in duration and diatoms are important primary producers with the potential to influence the carbon export budget. Different diatom species are more readily found in areas of low nutrients as opposed to areas of upwelling, depending on both their nutrient requirements for growth and their ability to access different nutrient sources. Along the California coast, upwelling occurring near thin continental shelf regions with low riverine iron input has been associated with iron limitation, while upwelling over a broad continental shelf region and/or close to riverine iron inputs has been found to be iron replete. Diatom quantification and community composition analysis was done on two transects, one transect followed upwelling waters close to a broad continental shelf with high riverine sources and one transect followed upwelling waters over a thinner continental shelf in a drier region. Diatom community composition shifted significantly along both transects suggesting a strong influence of upwelling on the community. Additionally, diatom community composition shifts through the high iron upwelling transect correlated 86% to phosphate and dissolved iron while the shifts in diatom community composition through the low iron upwelling transect correlated 60% to phosphate and copper. Combined, these results highlight the potential importance of both nutrients and trace metals in shaping the diatom community response to upwelling.
Einarsson, Sveinn; Abdala, Zuzy; Powell, Kimberly; Till, Claire P.; and Chappell, P. Dreux, "High and Low Iron Upwelling and Corresponding Shifts in the Diatom Community" (2019). College of Sciences Posters. 9.