Absorptance determinations on multicellular tissues
The analysis of the variation of the capacity and efficiency of photosynthetic tissues to collect solar energy is fundamental to understand the differences among species in their ability to transform this energy into organic molecules. This analysis may also help to understand natural changes in species distribution and/or abundance, and differences in species ability to colonize contrasting light environments or respond to environmental changes. Unfortunately, the challenge that optical determinations on highly dispersive samples represent has strongly limited the progression of this analysis on multicellular tissues, limiting our knowledge of the role that optical properties of photosynthetic tissues may play in the optimization of photosynthesis and growth of benthonic primary producers. The aim of this study is to stimulate the use of optical tools in marine eco-physiology, offering a succinct description of the more convenient tools and also solutions to resolve the more common technical difficulties that arise while performing optical determinations on highly dispersive samples. Our study focuses on two-dimensional (2D-) parameters: absorptance, transmittance, and reflectance, and illustrates with correct and incorrect examples, specific problems and their respective solutions. We also offer a general view of the broad variation in light absorption shown by photosynthetic structures of marine primary producers, and its low association with pigment content. The ecological and evolutionary functional implications of this variability deserve to be investigated across different taxa, populations, and marine environments.
KeywordsLight absorption Scattering Absorptance Reflectance Transmittance Macrophytes Corals
Three Mexican research projects DGAPA (IN206710); CONACYT (Conv-CB-2009: 129880); and CONACYT-104643 granted to SE have supported this research. The postgraduate program Posgrado en Ciencias del Mar y Limnología (PCMyL) of the Universidad Nacional Autónoma de México (UNAM) is acknowledged for providing the 2-year CONACYT fellowship to the Master thesis of L L-M and MA P-C and 3 years to TS and 4 years to RM V-E to support their respective PhD projects. One UNAM postdoctoral fellowship provided 2-year financial support to WEK. The authors would like to thank Dr. Eugenio R. Méndez for his kind and fundamental contributions to facilitate the immersion of marine biological students and researchers into the understanding of complex interactions between light and biological structures.
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