Role of structural colour in molecular mechanism of photosynthetic light harvesting in $Chondrus Crispus$.

$Chondrus Crispus$, red macroalgae, exhibits photonic structures in the isomorphic state gametophyte and is absent in the tetrasporophyte state of its lifecycle. Here, we have investigated the influence of structural coloration in the molecular mechanism of photosynthesis in the algae using time-resolved photoluminescence (TRPL) studies. We found that the lifetime of the pigments PE, PC and APC increases with an intensification in excitation intensity and the increment saturates toward the higher intensities. This observation can be attributed to the intensity-dependent photoprotection mechanism present in $Chondrus crispus$. Simulating the role of structural coloration in tetrasporophyte a similarity of the traces after intensity normalization considering the SC, confirms the role of SC in gametophyte in attenuating the photon flux reaching the photosynthetic organisms. These results show that a light management mechanism is present in the external antenna of the red algae associated with longer dynamics where SC on gametophyte tip helps in reducing the number of photons absorbed directly by the Chl and favoring the EET through the external antenna.