From "The Open Sea", Part 1: "The World of the Plankton", by Sir Alistair Hardy, 1956.


(thanks to Barney Balch for this quotation)

"A well-known herring skipper, Mr. Ronald Bells, who is also a keen naturalist, has recently written, under the pen-name of "Peko", an excellent article on this white water in World Fishing (July 1954). He describes how this water gives 'the queer impression of whiteness coming upwards: as if the light was below the sea instead of above it.' He then refers to recent views that the coccoliths are shields reflecting light from their owners which normally live in tropical seas where the illumination is too strong; 'and here', he writes, 'was the perfect explanation of the fairy glow or white reflection that I had experienced long ago, and wrote about before I knew even that this organism existed ...' "

Nowadays we suspect that the coccoliths do not act as light shields or light screens to protect their owners from the too-intense illumination. This is because (1) coccolith-bearing cells, (2) "naked" cells, and (3) Ehux cells with coccoliths removed by acid, all share the same response to very high light intensities. The light intensity at which the maximum photosynthetic rate is achieved is not affected by the possession of coccoliths (Paasche & Klaveness, 1970), and neither is the light intensity at which photoinhibition starts to decrease photosynthetic rate (Nanninga & Tyrrell, 1996). If the coccoliths were acting as light screens then we would expect different photosynthetic performance at high light intensities (e.g. no photoinhibition) when the cells are covered with coccoliths. Instead we see no significant difference.

It is now confirmed that the coccoliths themselves are causing the too-intense ambient illumination (see optics page), rather than reducing it for the cells they cover.

References

Ehux home page

Toby Tyrrell : T.Tyrrell@noc.soton.ac.uk