Accession Number : ADA623752


Title :   Photosymbiotic Giant Clams are Transformers of Solar Flux


Descriptive Note : Journal article


Corporate Author : CALIFORNIA UNIV SANTA BARBARA


Personal Author(s) : Holt, Amanda L ; Vahidinia, , Sanaz ; Gagnon, Yakir L ; Morse, Daniel E ; Sweeney, Alison M


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a623752.pdf


Report Date : Jan 2014


Pagination or Media Count : 16


Abstract : Giant tridacnid clams have evolved a three-dimensional, spatially efficient, photodamage-preventing system for photosymbiosis. We discovered that the mantle tissue of giant clams, which harbours symbiotic nutrition-providing microalgae, contains a layer of iridescent cells called iridocytes that serve to distribute photosynthetically productive wavelengths by lateral and forward-scattering of light into the tissue while back-reflecting non-productive wavelengths with a Bragg mirror. The wavelength- and angle-dependent scattering from the iridocytes is geometrically coupled to the vertically pillared microalgae, resulting in an even re-distribution of the incoming light along the sides of the pillars, thus enabling photosynthesis deep in the tissue. There is a physical analogy between the evolved function of the clam system and an electric transformer, which changes energy flux per area in a system while conserving total energy. At incident light levels found on shallow coral reefs, this arrangement may allow algae within the clam system to both efficiently use all incident solar energy and avoid the photodamage and efficiency losses due to non-photochemical quenching that occur in the reef-building coral photosymbiosis. Both intra-tissue radiometry and multiscale optical modelling support our interpretation of the system's photophysics. This highly evolved three-dimensional biophotonic system suggests a strategy for more efficient, damage-resistant photovoltaic materials and more spatially efficient solar production of algal biofuels, foods and chemicals.


Descriptors :   *BIOMATERIALS , *CLAMS , *ENERGY CONVERSION , *PHOTOSYNTHESIS , *SOLAR ENERGY , ABSORPTION , ALGAE , BIOPHYSICS , BRAGG ANGLE , CORAL REEFS , COUPLING(INTERACTION) , DIPOLES , EARTH MANTLE , ELECTRIC POWER , ENERGY , FLUX(RATE) , FORWARD SCATTERING , FREQUENCY , LIGHT SCATTERING , MONTE CARLO METHOD , OPTICAL PROPERTIES , POLARIZATION , RADIOMETRY , SHALLOW DEPTH , TISSUES(BIOLOGY)


Subject Categories : Biochemistry
      Biology
      Electric Power Production and Distribution
      Optics


Distribution Statement : APPROVED FOR PUBLIC RELEASE