Microphytobenthos primary production estimated by hyperspectral reflectance

PLoS One. 2018 May 14;13(5):e0197093. doi: 10.1371/journal.pone.0197093. eCollection 2018.

Abstract

The use of remote sensing techniques allows monitoring of photosynthesis at the ecosystem level and improves our knowledge of plant primary productivity. The main objective of the current study was to develop a remote sensing based method to measure microphytobenthos (MPB) primary production from intertidal mudflats. This was achieved by coupling hyperspectral radiometry (reflectance, ρ and second derivative, δδ) and PAM-fluorometry (non-sequential light curves, NSLC) measurements. The latter allowed the estimation of primary production using a light use efficiency parameter (LUE) and electron transport rates (ETR) whereas ρ allowed to estimate pigment composition and optical absorption cross-section (a*). Five MPB species representative of the main growth forms: epipelic (benthic motile), epipsammic (benthic motile and non motile) and tychoplanktonic (temporarily resuspended in the water column) were submitted to increasing light intensities from dark to 1950 μmol photons.m-2.s-1. Different fluorescence patterns were observed for the three growth-forms and were linked to their xanthophyll cycle (de-epoxydation state). After spectral reflectance measurements, a* was retrieved using a radiative transfer model and several radiometric indices were tested for their capacity to predict LUE and ETR measured by PAM-fluorometry. Only one radiometric index was not species or growth-form specific, i.e. δδ496/508. This index was named MPBLUE and could be used to predict LUE and ETR. The applicability of this index was tested with simulated bands of a wide variety of hyperspectral sensors at spectral resolutions between 3 and 15 nm of Full Width at Half Maximum (FWHM).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomass*
  • Diatoms* / chemistry
  • Diatoms* / growth & development
  • Fluorometry / methods*

Associated data

  • figshare/5615746

Grants and funding

This work is supported by the Centre National de la Recherche Scientifique-CNRS (sabbatical and EC2CO grant to VM), the Region Poitou-Charentes (Ph.D. grant to AB), the French consortium CPER-Littoral (to JL), the Region Pays de la Loire (Atlantic Micro-algae program to VM) and the Fondation de France (grant ‘Quels littoraux pour demain ?’ to JL and VM); the Planetology and Geodynamic laboratory (UMR 6112, University of Nantes-CNRS) for supplying the ASD FieldSpec3spectrometer. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.