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SPATIAL AND TEMPORAL VARIABILITY IN PHOSPHORUS INVENTORIES AND TURNOVER OF INORGANIC P AND ADENOSINE-TRIPHOSPHATE IN THE NORTH PACIFIC

The multi-year variability in the dissolved inorganic, and organic phosphate (Pi, DOP) pools, and the microbial community’s utilization of Pi and adenosine-5’-triphosphate (ATP) was studied at Station ALOHA in the North Pacific Subtropical Gyre (NPSG). The spatial variability of these same parameters was investigated along two transects that included traversing the gyre boundary. We used radiotracer techniques to determine the turnover time of Pi or ATP. Both spatially and temporally the Pi pools were much more dynamic than DOP, ranging two orders of magnitude compared to a factor of two for DOP. The Pi-pool turnover time ranged from a few hours to several weeks, and was strongly correlated with measured Pi pool concentrations (r2=0.8; n=30 Station ALOHA; n=15 2014, r2=0.9; n=14, 2016). The Pi uptake rates along the two transects averaged 9.2±4.7 nM-P d-1, n=15 (2014) and 4.8±2.6 nM-P d-1, n=13 (2016) whereas rates at Station ALOHA averaged 3.7±1.3 nM-P d-1 (n=30). The turnover time of the dissolved ATP pool was typically substantially shorter than for the Pi-pool. Only at very low Pi was ATP turnover longer than for Pi. Total ATP hydrolysis was high along both transects, exceeding the ATP-Pi taken up by the microbial community, resulting in a net release of Pi into the ambient seawater. The results indicate that during Pi limiting conditions regenerated P is rapidly consumed, and that Pi limitation occurs locally and transiently but appears not to be the predominant condition in the upper water column of the NPSG.

Authors

Björkman, K. M., University of Hawaii, USA, bjorkman@hawaii.edu

Duhamel, S., Lamont-Doherty Earth Observatory, USA, sduhamel@ldeo.columbia.edu

Church, M. J., University of Montana, USA, mjchurch@hawaii.edu

Karl, D. M., University of Hawaii, USA, dkarl@hawaii.edu

Details

Poster presentation

Session #:040
Date: 03/01/2017
Time: 15:30 - 16:30
Location: Poster/Exhibit Hall

Presentation is given by student: No

PosterID: 351