Young ISDR

by Johannes W. Goessling* The centric diatom Coscinodiscus granii lives in coastal and pelagic marine habitats as a cosmopolitan phytoplanktonic species (algaebase.org) . The genus name is derived from the greek words kóskino (sieve) and dískos (disc) and refers to the disc-shaped structure of the two valves that compose the silicate envelope ( frustule ) surrrounding diatoms. The valves of C. granii are perforated with pores and chambers in an outer layer with small pores (~10 nm), a central layer with hexagonal chambers (~1,200 nm), and an inner layer with large pores (~580 nm) (Fig. 1). So the size of these structures is only 1/100,000 th to 1/1000 th of a mm (!) and can therefore interact with the photons of sunlight. We were interested in the physical interaction of frustules with light, and how it can affect diatom photosynthesis – the conversion of sunlight into chemical energy. We found that the C. granii frustule redistributes sunlight to optimize the exposure...