Seasonal Changes of Bioluminescence in Photosynthetic and Heterotrophic Dinoflagellates at San Clemente Island

A significant portion of bioluminescence in all oceans is produced by dinoflagellates. Numerous studies have documented the ubiquitous distribution of bioluminescent dinoflagellates in near surface waters (Seliger et al., 1961; Yentsch and Laird 1968; Tett 1971; Tett and Kelly 1973). The number of bioluminescent species and their relative abundance change temporally, with depth, and geographically. Dinoflagellates are most abundant in coastal waters and inland seas and are less abundant in the open ocean (Colebrook and Robinson, 1965; Dodge and Hart-Jones, 1977). Studies have been conducted to determine the species contributing to bioluminescence. In several studies, this involved making plankton collections, isolation and measurement of cells with a laboratory photometer to quantify the light output of several species of bioluminescent dinoflagellates (Lapota and Losee 1984; Batchelder and Swift 1989; Lapota et al., 1992a,b; Swift et al., 1995). These studies were limited to short sampling periods (days-weeks) and to specific locations. There is also evidence that dinoflagellates undergo changes in light output which may be attributable to environmental conditions. For example, cells of Protoperidinium spp. produce more bioluminescence when nutritional requirements were optimized in the laboratory (Buskey 1992; Latz 1993). Others have observed that the bioluminescence potential of a dinoflagellate is related to its surface area or cell volume for several species, which might be related to light and nutrient history (Seliger et al. 1969; Seliger and Biggley 1982; Swift et al. 1995; Sullivan and Swift 1995). Bioluminescence may also be a function of light, temperature, and nutrient history (Sweeney, 1981). Other data have suggested that cells of the same species in the same study display differences in bioluminescence. These observations may indicate that cells are exposed to a wide range of environmental conditions affecting light output on a short time scale such as light history, nutrient history, grazing pressure by herbivores and consequent loss of potential bioluminescent capacity (Swift et al., 1981; Sullivan and Swift, 1995).