ANNUAL VARIABILITY IN THE ABUNDANCE AND DIVERSITY OF LARGE DIAZOTROPHS AT STATION ALOHA
Although they are relatively rare in terms of cell concentrations, the activity of large N2-fixing micro-organisms (termed diazotrophs) has been implicated as a major driver of new production and particle export in the oligotrophic North Pacific Subtropical Gyre. In coordination with the Hawaii Ocean Time-Series and as a component of several regional process cruises, we have collected near monthly samples for microscopic enumeration of Trichodesmium and diatom-Richelia assemblages spanning March, 2015 to August, 2016 at Station ALOHA. To our knowledge, this is an unprecedented dataset, particularly in the genomic era when microscopy-based measures of taxonomic diversity are becoming increasingly rare. In this presentation, we will describe the temporal patterns in the abundance of Trichodesmium and Richelia and their host diatoms relative to predominant chemical, physical, and climactic forcing in the NPSG. When data are available, we will also compare our findings to measures of particle flux and primary productivity. The aim of this work is to gain a better understanding of the temporal variability of large diazotrophs and their impact on biogeochemical cycling and particle export in the region.
White, A. E., Oregon State University, USA, firstname.lastname@example.org
Watkins-Brandt, K. S., Oregon State University, USA, email@example.com
Presentation is given by student: No