Contributions of phytoplankton and bacteria to the optical backscattering coefficient over the Mid-Atlantic Ridge

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 445:37-51 (2012) - DOI: https://doi.org/10.3354/meps09388 Contributions of phytoplankton and bacteria to the optical backscattering coefficient over the Mid-Atlantic Ridge Victor Martinez-Vicente*, Gavin H. Tilstone, Shubha Sathyendranath, Peter I. Miller, Steve B. Groom Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3DH, UK *Email: vmv@pml.ac.uk ABSTRACT: Understanding the sources of the optical backscattering coefficient from particles (bbp) aids interpretation of ocean colour measured from satellites. The hypothesis tested is that phytoplankton make a significant contribution to the bbp in the open ocean. Using phytoplankton pigment, flow cytometry and microscopy data, measured concurrently with in situ bbp in the central North Atlantic Ocean, we separated the phytoplankton signal from that of bacteria. Three distinct pelagic communities were detected, all associated with the sub-polar front. A significant percentage of variance in the bbp signal (r2 = 0.68) was explained by phytoplankton between 2 and 20 µm in diameter (nanoeukaryotes). To further test the hypothesis, bbp was calculated using literature values of the backscattering properties and cell size of phytoplankton and flow-cytometric cell counts. In agreement with previous modelling studies, bacteria, due to their great abundance, dominate the biological bbp signal. However, the variations in bbp were related to changes in phytoplankton abundance (particularly of nanoeukaryotes), and the use of high backscattering efficiency factors per cell for nanoeukaryotes yielded computed values close to the observed bbp. We found no evidence that the detrital component played a significant role in bbp at this site. However, given the limited methods available to test this result, such lack of evidence is inconclusive. To be able to explain the remaining proportion of the variation in bbp, a significant methodological advance is required for the better quantification and characterisation of the organogenic detritus. KEY WORDS: Optical backscattering · Mid-Atlantic Ridge · Optics · Nanoeukaryotes · Bacteria Full text in pdf format PreviousNextCite this article as: Martinez-Vicente V, Tilstone GH, Sathyendranath S, Miller PI, Groom SB (2012) Contributions of phytoplankton and bacteria to the optical backscattering coefficient over the Mid-Atlantic Ridge. Mar Ecol Prog Ser 445:37-51. https://doi.org/10.3354/meps09388 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 445. Online publication date: January 20, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.