Decoupling between bacterial production and primary production over multiple time scales in the North Pacific Subtropical Gyre. (March 2017)

• Record Type: Journal Article
• Authors: Viviani, Donn A.; Church, Matthew J.
• Is Part Of: Deep sea research. Volume 121(2017)
• Page Start: 132
• Page End: 142
• Publication Date: 2017-03
• Subjects: 3H-leucine incorporation -- Primary production -- Time-series -- North Pacific Ocean -- Station ALOHA; Oceanography -- Periodicals; Océanographie -- Périodiques; 551.4605
• DOI: 10.1016/j.dsr.2017.01.006
• Languages: English
• ISSNs: 0967-0637

Abstract

Abstract: We measured rates of 3 H-leucine ( 3 H-Leu) incorporation, as a proxy for bacterial production, at Station ALOHA (22°45′N, 158°W) in the oligotrophic North Pacific Subtropical Gyre (NPSG). We report measurements conducted between January 2011 and April 2013, examining variability in 3 H-Leu incorporation over diel, daily, and monthly time scales. Rates of 3 H-Leu were evaluated in the context of contemporaneous 14 C-based primary productivity ( 14 C-PP) to identify potential temporal coupling between these measures of productivity. Throughout the upper ocean (0–125 m), rates of 3 H-Leu incorporation measured in the light ( 3 H-LeuLight ) were stimulated (1.5-fold, on average) relative to measurements in the dark ( 3 H-LeuDark ). At monthly scales, rates of 3 H-LeuLight and 3 H-LeuDark varied 4.9-fold and 3.8-fold, respectively, while rates of 14 C-PP varied 1.7-fold. Rates of 14 C-PP were often elevated during summer months (May through August) when incident light flux was greatest, while rates of both 3 H-LeuLight and 3 H-LeuDark often peaked in early fall (August through October) when seawater temperatures were maximal. Near-daily measurements of 3 H-Leu incorporation and 14 C-PP conducted over a 62-day period in the summer of 2012 revealed that rates of 3 H-LeuLight and 3 H-LeuDark varied ~2.5 and 2.0-fold, respectively, similar to ~1.8-fold daily variability observed in rates of 14 C-PP. Over diel time scales, rates of 3 H-LeuLight and 3 H-LeuDark demonstrated different patterns, with rates of 3 H-LeuLight elevated at mid-day and rates of 3 H-LeuDark greatest in the early evening. Together, these results suggest that in this oligotrophic ecosystem, photosynthetic production of organic matter and bacterial production can be temporally uncoupled across daily to seasonal scales. Highlights: Primary and bacterial production time-series in the oligotrophic North Pacific Ocean. Production rates measured over nested time scales (diel, daily, monthly, seasonal). Coupling between primary and bacterial production evaluated at variable time scales. Primary and bacterial production were decoupled over monthly and seasonal scales.