COS 245-3 - CANCELLED - Adaptations of global phytoplankton compositions and its role in oceanic biogeochemical cycles and ecosystem

Background/Question/Methods

The dominance of larger cell phytoplankton diatoms observed throughout the Southern Ocean (SO) and Arctic Ocean (AO); however, the coccolithophores dominance observed in remaining part of the Global Ocean (GO). Nutrients such as nitrate is not a limiting factor for the variability of phytoplankton biomass in the SO and AO other hand, low nitrates has influenced in the rest of the GO. The photosynthetically available radiation (PAR) is limiting the phytoplankton biomass and composition in the SO and AO, even if the SO is high nutrient low chlorophyll (HNLC) region. The low iron concentration along with the PAR co-limits the growth of phytoplankton biomass in the region. Trend analysis resulted the increase in Chl a and diatoms in the SO and AO; and declined significantly in the GO, in response to the invariable increase in sea surface temperature. The consequences indicated shifting of phytoplankton community along regional to global scale has a greater implication for global climate change and its impact on the marine ecosystem.

Results/Conclusions

The average upper global ocean of Chl-a and di< ![if !supportFootnotes] >[1]< ![endif] >atoms declined over the study period, is concomitant with previous report on decline of global Chl-a; however, the absolute magnitude of this change remains indecisive. The photosynthetically available radiation (PAR) was limiting phytoplankton biomass and composition in SO and AO. Although SO is known as high nutrient low chlo< ![if !supportFootnotes] >[1]< ![endif] >rophyll (HNLC) region of GO, the low iron concentration along with PAR co-limits the growth of phytoplankton biomass. The Chl-a and diatoms trend analysis showed an increase in SO and AO; however, the variables declined significantly in GO in response to consistent increase in SST. Analysis of cyanobacteria trend showed a significant increase in GO compared to SO and AO. In contrary, the coccolithophores declined in GO, SO, and AO. In SO, there is a significant increasing trend in nutrients, MLD, and PAR, influenced the chlorophytes and diatoms. Declining of global Chl-a, increasing trend of cya< ![if !supportFootnotes] >[1]< ![endif] >nobacteria and increasing trend of SST consistent lead to hypothesis that the ocean warming is causing to reform a marine ecosystem with an implication of biogeochemical cycling, primary productivity, fishery productivity and ocean circulation.