Program and Agenda

Abstract

DIVERSITY TRUMPS ACIDIFICATION: NO CO2 ENHANCEMENT OF N2 FIXATION BY THE TRICHODESMIUM COMMUNITY AT STATION ALOHA

Several recent laboratory studies have shown that elevated pCO2 enhances N2 fixation by isolates of Trichodesmium and Crocosphaera, suggesting that future climate change may increase global N2 fixation rates. However, it is unclear whether the evidence for a pCO2 enhancement of N2 fixation by laboratory isolates can be used to predict the response of diverse diazotrophic communities under natural environmental conditions. To address this problem, we conducted eleven independent CO2 manipulation experiments in the North Pacific using Trichodesmium colonies collected at Station ALOHA. Our results indicate that elevated pCO2 has no significant effect on N2 or C fixation rates by Trichodesmium at Station ALOHA. At the time of our sampling, differences between pCO2 treatments were not modulated by phosphorus amendments, iron amendments, or photon flux. Molecular analyses of the colonies revealed a highly diverse community of Trichodesmium and other N2-fixing colony-associated organisms. We suggest that this diversity can explain the lack of an observed CO2 enhancement of N2 or C fixation rates, as different species are known to have different specific affinities for CO2.

Authors

Gradoville, M. R., Oregon State University, USA, rgradoville@coas.oregonstate.edu

White, A. E., Oregon State University, USA, awhite@coas.oregonstate.edu

Böttjer, D., University of Hawaii at Manoa, USA, dbottjer@hawaii.edu

Church, M. J., University of Hawaii at Manoa, USA, mjchurch@hawaii.edu

Letelier, R. M., Oregon State University, USA, letelier@coas.oregonstate.edu

Details

Oral presentation

Session #:125
Date: 2/24/2014
Time: 08:30
Location: 301 AB

Presentation is given by student: Yes