The Relation Between Dinoflagellates And The Bioluminescence Of Sea Water

Evidence is given in support of the assertion that dinoflagellates are responsible for a large part of surface water luminescence. Literature records of species of dinoflagellates tested for luminescence ability are summarized and are supplemented by the results of tests carried out on dinoflagellate cells picked out from Firth of Clyde sea water samples. In these tests the following species were found to be luminescent which had not previously been convincingly described as possessing this ability: Peridinium divergens, P. ovatum, P. steinii, Gonyaulax catenata and Polykrikos schwartzii. In darkness, an untouched sea water sample containing luminescent dinoflagellates will emit spontaneous luminescence. The rate of emission of luminescent flashes was found to be significantly correlated with the numbers of luminescent dinoflagellates (mostly Peridinium spp.) in series of water samples from the Firth of Clyde and from the Plymouth area. There was no significant correlation between luminescence and the numbers of dinoflagellates assumed to be nonluminescent. A significant correlation was also found between the amounts of luminescence produced upon stimulation of Clyde sea water samples and the numbers of luminescent dinoflagellates in these samples. It was concluded that the species of dinoflagellates which were known to be luminescent were the only major source of bioluminescence in the samples studied. There was much variation between samples in the amount of luminescence emitted per luminescent dinoflagellate cell (F/L), although there was a significant correlation between the F/L values for spontaneous and stimulated luminescence. Anumber of reasons which might account for the variation in F/L are discussed. A seasonal trend in F/L values may be explained by the influence of nutritional factors on dinoflagellates.