Chlorophyll a and intertidal epilithic biofilms analysed in situ using a reflectance probe

Abstract

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 12:165-176 (2011) - DOI: https://doi.org/10.3354/ab00334 Chlorophyll a and intertidal epilithic biofilms analysed in situ using a reflectance probe Richard J. Murphy1,2,*, Judith C. Klein2, Antony J. Underwood2 1Australian Centre for Field Robotics, Dept. of Aerospace, Mechanical & Mechatronic Engineering, University of Sydney, New South Wales 2006, Australia 2Centre for Research on Ecological Impacts of Coastal Cities, School of Biological Sciences, Marine Ecology Laboratories, A11, University of Sydney, New South Wales 2006, Australia *Email: [email protected] ABSTRACT: Spectrometry of biofilms in microhabitats (e.g. rock crevices) is difficult using natural light. An alternative approach was evaluated using a reflectance probe with an artificial light source to measure the abundance and pigment composition of intertidal biofilms in situ. Measurements made by the probe were compared with those made under sunlight. To determine whether the probe could be used to measure amounts of chlorophyll a (chl a, as an index of biomass), reflectance spectra (350–1050 nm) were acquired from microalgae grown on sandstone discs. Spectra were acquired under natural light and using the probe (artificial light) with or without an intervening layer of plastic. Two chlorophyll indices (a ratio of reflectances at 750 and 672 nm and the Phytobenthos Index) were used to estimate amounts of chl a from the spectra. Strong linear relationships were found between laboratory measures of chl a and both chlorophyll indices (R2 ranging from 0.85 to 0.94). Spectra of natural intertidal biofilms were used to determine whether there were any differences between spectra measured under natural and artificial light in terms of the shapes of their curves and the wavelengths and heights of absorption peaks caused by photosynthetically active pigments. No differences in shapes of curves were found between spectra measured under natural and artificial light. The wavelength positions of absorption peaks were similar between spectra measured under sunlight and artificial light but there were differences in their height. Taken together, results show that the reflectance probe presented a reliable and rapid method for providing quantitative and qualitative information about intertidal biofilms in situ. KEY WORDS: Microalgae · Reflectance · Intertidal · Chlorophyll · Pigments · Biofilm · Spectra Full text in pdf format PreviousNextCite this article as: Murphy RJ, Klein JC, Underwood AJ (2011) Chlorophyll a and intertidal epilithic biofilms analysed in situ using a reflectance probe. Aquat Biol 12:165-176. https://doi.org/10.3354/ab00334 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 12, No. 2. Online publication date: May 05, 2011 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2011 Inter-Research.