Relationships between sea ice and phytoplankton bloom net community production in the Southern Ocean seasonal sea ice zone
Shannon McClish, University of Hawaii, Honolulu, smcclish@hawaii.edu
Seth Bushinsky, University of Hawaii at Manoa, seth.bushinsky@hawaii.edu (Presenter)
The Southern Ocean Seasonal Sea Ice Zone (SIZ) spring is characterized by sea ice retreat and the development of phytoplankton blooms. While the existence of blooms associated with retreating sea ice is well documented, the importance of under-ice production and the bloom’s impact on carbon and nutrient cycling is unclear. We utilize circumpolar biogeochemical profiling float observations to assess SIZ blooms and associated bloom net community production (bNCP). We examine 64 individual float seasons and relate the timing of sea ice retreat to phytoplankton growth, the drawdown of surface nitrate, and estimated bNCP. The onset of biological production follows initial sea ice breakup and the majority of bNCP occurs under partial sea ice cover. Estimates of bNCP range from <1 to >4 mol C m-2 bloom-1, with higher bNCP when sea ice breakup occurs early in the year, and the highest bNCP observed by floats where micronutrients may be supplied from continental sources or topographically-enhanced mixing. We hypothesize that differences in the timing of sea ice breakup and retreat may alter ecosystem dynamics that control bNCP, and that micronutrient limitation and grazing may lead to decreased NCP rates after total sea ice retreat. These results indicate that satellite-derived export estimates will underestimate bNCP in the SIZ and have implications for net community production in the currently changing Southern Ocean sea ice regime.
Poster: Poster_McClish_3-15_115_35.pdf
Associated Project(s):
Poster Location ID: 3-15
Presentation Type: Poster
Session: Poster Session 3
Session Date: Thu (May 11) 3:00-5:00 PM
CCE Program: OBB