**4. Discussion**

20 Bioluminescence – Recent Advances in Oceanic Measurements and Laboratory Applications

Fig. 20. Integrated bioluminescence (photons sec-1 m-2) and Chl *a* (mg m-2) averages of all

The vertical structure within the water column with respect to other measured parameters (temperature, percent light transmission, and in vivo Chl fluorescence) changed seasonally (Figure 21). For example, at Station 3 in July (7/12/94), bioluminescence was significantly correlated with *in vivo* Chl fluorescence (r = 0.673; p < 0.001), beam attenuation (r = 0.747; p < 0.001), and temperature (r = 0.892; p < 0.001; Figure 21). Beam attenuation was positively correlated with *in vivo* Chl fluorescence (r = 0.831; p < 0.001). Maximum bioluminescence and *in vivo* Chl fluorescence were measured at the bottom of the mixed layer (20 m below the sea surface). The mixed layer deepened in November (11/10/94) as did maximum bioluminescence and Chl fluorescence. The correlation between bioluminescence and chlorophyll fluorescence (r = 0.483; p < 0.001) in November was significant as was bioluminescence and beam attenuation (r = 0.954; p <0.001) and bioluminescence with

stations from 1994-1996. Averages of individual stations are also shown.

The data show that bioluminescence changes seasonally in the Southern California Bight coastal waters with a maximum and minimum signal in the spring and fall in SDB (Figures 2,14,17b,19a). A winter maximum and summer minimum in bioluminescence was measured at SCI (Figure 2, 17a). In SDB and SCI, we observed a change in the dinoflagellate species composition over a year and its contribution to bioluminescence. We also observed a seasonal change in species composition (summer to winter) at SCI and within the bight (Figures 8a, 9, 10). Chlorophyll *a* also showed similar seasonal trends with respect to location (Figures 18,19). However, measured monthly means of bioluminescence did not correlate with Chl *a* either at SDB or SCI. Mean monthly surface seawater temperature did not correlate with mean monthly bioluminescence at either site; that is, maximum bioluminescence did not always correlate with either maximum or minimum seawater temperatures (Figures 11, 12), although minimum bioluminescence was measured during the coolest water temperatures (winter) at SDB in 1994 and 1996. The largest peak in bioluminescence measured at SCI (winter 1995) was associated with the coolest seawater temperatures (14-15°C) during winter (Figure 12). Coolest water temperatures did not correlate with the upwelling index as maximum indices for 33°N latitude, 119°W longitude generally occurred in June of each year.

Total bioluminescence (photons ml-1 year-1) was always greater at SDB than at SCI. Total bioluminescence at SDB ranged from 1.06 x 1013 to 1.93 x 1013 photons ml-1 year-1 (measured from 2100 to 0300 hrs each day) while total bioluminescence measured at SCI was from 3.45 x 1012 to 9.91 x 1012 photons ml-1 year-1. In 1993-1994, 3 times more bioluminescence was measured at SDB than at SCI. These differences lessened to a factor of 2 in 1994-1995 between both sites when a massive bioluminescence red tide was observed to extend south from Santa Barbara, California to Ensenada, Mexico and 100km offshore to SCI. At times, monthly differences in total bioluminescence were 8 times greater at SDB than at SCI in Spring 1994 and 1995.

Bioluminescent dinoflagellates, in most instances, comprised most of the dinoflagellates collected at SDB and SCI (Figures 3, 7). In SDB, bioluminescent dinoflagellates made up at least 80% of all dinoflagellates. Numbers of bioluminescent dinoflagellates dropped noticeably in the winter and spring at SDB (< 30% of total dinoflagellates) at SDB. Decreases in bioluminescent dinoflagellates were observed at SCI in late spring at SCI. The bioluminescent dinoflagellate assemblage at both SDB and SCI was composed of *Ceratium*, *Gonyaulax*, *Protoperidinium*, and *Noctiluca* species. *Pyrocystis noctiluca* was a recurring species

Long Term Dinoflagellate Bioluminescence, Chlorophyll,

land (Eppley et al. 1978).

and runoff.

and Their Environmental Correlates in Southern California Coastal Waters 23

found at SCI. *Protoperidinium* spp. and *Gonyaulax polyedra* contributed most of the bioluminescence at both sites. *Noctiluca miliaris* contributed substantial bioluminescence

Total rainfall was significantly correlated with measured bioluminescence at SDB (r = 0.908; n = 4; p < 0.05). Years with the greatest rainfall (1993, 1995) affected the total bioluminescence which implies that processes associated with rainfall, such as storm water runoff may be stimulating dinoflagellate and algal production in coastal waters (Anderson 1964; Eppley et al., 1978). We observed that the upwelling index did not directly correlate with SDB bioluminescence unless the index was shifted back 1 month (r = 0.476; p < 0.001). However, if mean monthly bioluminescence was shifted forward 2 months with mean rainfall, a significant correlation was observed (r = 0.472; p < 0.01). The upwelling index and nitrates (µm L-1) measured in coastal waters, were significantly correlated when nitrate levels were shifted forward in time 1 month (r = 0.679; p < 0.001). We must then assume that some other factor besides upwelling is providing a stimulatory effect to dinoflagellate bioluminescence. Multiple regression analysis showed that rainfall, upwelling, and temperature were the most important conditions to predict bioluminescence and that when rainfall was moved ahead in time by 2 months, we could account for 24.7% of the observed variance to predict bioluminescence from 1992 - 1996 (R2 = 0.2468; F=2.469; p<0.05). Increased nitrate levels were observed in coastal waters beyond SCI during the winter months and spring months; before maximum upwelling. The source of these nitrates may be in storm water runoff. Support for "new sources of nitrogen" versus "recycled nitrogen" and other nutrients entering the water column is not new. Some studies have shown that river inputs into the ocean can carry high levels of nutrients needed for algal growth (Harrison 1980, Fogg 1982, Mooers et al. 1978, Lalli and Parsons, 1993). Others have found that ferric iron is a limiting nutrient for phytoplankton growth (Menzel and Ryther 1961) and that high levels of iron are often associated with river runoff (Williams and Chan 1966). Iron is needed by phytoplankton to utilize nitrates for growth (Ryther and Kramer 1961). The availability of iron is enhanced by chelation with dissolved organic matter. That is, organically bound iron from storm runoff may stimulate the growth of phytoplankton (Kawaguchi and Lewitus 1996). Similarly, elevated phytoplankton levels off Del Mar, California following storm water runoff were attributed to increased nutrient inputs from

The bathyphotometer stations showed that bioluminescence and Chl fluorescence were positively correlated, during the summer months, when the water column stabilized with a shallow thermocline. These significant positive correlations broke down with water column mixing during the fall and winter months but were reestablished with the development of the thermocline during the spring and summer months. Several species of *Protoperidinium*  were the predominant dinoflagellate in the spring and summer months while *G. polyedra*  was important during the fall and winter months; not only in surface waters, but at depth. The increased bioluminescence and chlorophyll levels associated with the red tide at SCI are remarkable for their duration since they persisted from January through April 1995. This strengthens the inference that the physical environment in the bight is fairly stable with respect to seasonality, and that bioluminescence is strongly influenced by seasonal rainfall

following increases in *G. polyedra* at SDB in 1995 and 1996 and at SCI in 1995.

Fig. 21. Bathyphotometer profiles at station 3 for (a) July 12, 1994; (b) station 3 November 10, 1994; (c) station 3 February 12, 1995; (d) station 3 June 13, 1995.

Fig. 21. Bathyphotometer profiles at station 3 for (a) July 12, 1994; (b) station 3 November 10,

1994; (c) station 3 February 12, 1995; (d) station 3 June 13, 1995.

found at SCI. *Protoperidinium* spp. and *Gonyaulax polyedra* contributed most of the bioluminescence at both sites. *Noctiluca miliaris* contributed substantial bioluminescence following increases in *G. polyedra* at SDB in 1995 and 1996 and at SCI in 1995.

Total rainfall was significantly correlated with measured bioluminescence at SDB (r = 0.908; n = 4; p < 0.05). Years with the greatest rainfall (1993, 1995) affected the total bioluminescence which implies that processes associated with rainfall, such as storm water runoff may be stimulating dinoflagellate and algal production in coastal waters (Anderson 1964; Eppley et al., 1978). We observed that the upwelling index did not directly correlate with SDB bioluminescence unless the index was shifted back 1 month (r = 0.476; p < 0.001). However, if mean monthly bioluminescence was shifted forward 2 months with mean rainfall, a significant correlation was observed (r = 0.472; p < 0.01). The upwelling index and nitrates (µm L-1) measured in coastal waters, were significantly correlated when nitrate levels were shifted forward in time 1 month (r = 0.679; p < 0.001). We must then assume that some other factor besides upwelling is providing a stimulatory effect to dinoflagellate bioluminescence. Multiple regression analysis showed that rainfall, upwelling, and temperature were the most important conditions to predict bioluminescence and that when rainfall was moved ahead in time by 2 months, we could account for 24.7% of the observed variance to predict bioluminescence from 1992 - 1996 (R2 = 0.2468; F=2.469; p<0.05). Increased nitrate levels were observed in coastal waters beyond SCI during the winter months and spring months; before maximum upwelling. The source of these nitrates may be in storm water runoff. Support for "new sources of nitrogen" versus "recycled nitrogen" and other nutrients entering the water column is not new. Some studies have shown that river inputs into the ocean can carry high levels of nutrients needed for algal growth (Harrison 1980, Fogg 1982, Mooers et al. 1978, Lalli and Parsons, 1993). Others have found that ferric iron is a limiting nutrient for phytoplankton growth (Menzel and Ryther 1961) and that high levels of iron are often associated with river runoff (Williams and Chan 1966). Iron is needed by phytoplankton to utilize nitrates for growth (Ryther and Kramer 1961). The availability of iron is enhanced by chelation with dissolved organic matter. That is, organically bound iron from storm runoff may stimulate the growth of phytoplankton (Kawaguchi and Lewitus 1996). Similarly, elevated phytoplankton levels off Del Mar, California following storm water runoff were attributed to increased nutrient inputs from land (Eppley et al. 1978).

The bathyphotometer stations showed that bioluminescence and Chl fluorescence were positively correlated, during the summer months, when the water column stabilized with a shallow thermocline. These significant positive correlations broke down with water column mixing during the fall and winter months but were reestablished with the development of the thermocline during the spring and summer months. Several species of *Protoperidinium*  were the predominant dinoflagellate in the spring and summer months while *G. polyedra*  was important during the fall and winter months; not only in surface waters, but at depth. The increased bioluminescence and chlorophyll levels associated with the red tide at SCI are remarkable for their duration since they persisted from January through April 1995. This strengthens the inference that the physical environment in the bight is fairly stable with respect to seasonality, and that bioluminescence is strongly influenced by seasonal rainfall and runoff.

Long Term Dinoflagellate Bioluminescence, Chlorophyll,

10 (supplement), R54-66.

Oceanogr. 11: 548-561.

England, pp. 141-143.

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511-520.

significance. Limnol. Oceanogr. 12: 685-695.

Biology 31, Plenum, New York, pp. 433-460.

Carolina, USA, 20-23 November 1996.

Monitoring Program 1994-1995, Carlsbad, Calif.

the Sea of Cortez. J. exp. Mar. Biol. Ecol. 77: 209-240.

Norwegian fjord. Mar. Ecol. Prog. Ser. 55: 217-227.

milky sea. J. exp. Mar. Biol. Ecol. 119: 55-81.

and Their Environmental Correlates in Southern California Coastal Waters 25

Biggley, W.H., Swift, E., Buchanan, R.J., Seliger, H.H. (1969). Stimulable and spontaneous

 Bityukov, E.P., Rybasov, V.P., Shaida, V.G. (1967). Annual variations of the bioluminescent field intensity in the neritic zone of the Black Sea. Oceanology 7 (6): 848-856. Case, J.F., Widder, E.A., Bernstein, S., Ferer, K., Young, D., Latz M., Geiger, M., Lapota, D. 1993). Assessment of marine bioluminescence. Nav. Res. Rev. 45: 31-41. Clarke, G.L., Kelly, M.G. (1965). Measurements of diurnal changes in bioluminescence from

Dugdale, R.C. (1967). Nutrient limitation in the sea: dynamics, identification and

Eppley, R.W., Sapienza, C., Renger, E.H. (1978). Gradients in phytoplankton stocks and nutrients off southern California in 1974-76, Estuarine Coastal Mar. Sci. 7: 291-301. Eppley, R.W. (1986). Plankton Dynamics of the Southern California Bight, Lecture Notes on

Fogg, G.E. (1982). Nitrogen cycling in sea waters. Phil. Trans. Roy. Soc. Lond. Ser. B, 296:

Harrison, W.G. (1980). Nutrient regeneration and primary production in the sea. In:

Hayward, T.L., Cummings, S.L., Cayan, D.R., Chavez, F.P., Lynn, R.J., Mantyla, A.W.,

during a period of nearly normal circulation. CalCOFI Reports 37: 22-37. Holm-Hansen, O., Strickland, J.D.H., Williams, P.M. (1966). A detailed analysis of

Kawaguchi, T., Lewitus, A.J. (1996). The potential effect of urbanization on iron

Kinnetic Laboratories, Inc (1995). City of San Diego and Co-Permittee Stormwater

Lalli, C.M., Parsons, T.R. (1993). Biological Oceanography*,* Pergamon Press, Oxford,

Lapota, D., Losee, J.R. (1984). Observations of bioluminescence in marine plankton from

Lapota, D., Galt, C., Losee, J.R., Huddell, H.D., Orzech, K., Nealson, K.H. (1988).

Lapota, D., Geiger, M.L., Stiffey, A.V., Rosenberger, D.E., Young, D.K. (1989). Correlations

Lapota, D., Rosenberger, D.E. (1990). Bioluminescence measurements and light budget analysis in the western Arabian Sea. EOS, Trans. of the Am. Geophy. Union 71: 97. Lapota, D., Rosenberger, D.E., Lieberman, S.H. (1992a). Planktonic bioluminescence in the pack ice and the marginal ice zone of the Beaufort Sea. Mar. Biol. 112:665-675.

Observations and measurements of planktonic bioluminescence in and around a

of planktonic bioluminescence with other oceanographic parameters from a

polyedra*,* and Pyrocystis lunula. J. Gen. Physiol. 54: 96-122.

bioluminescence in the marine dinoflagellates, Pyrodinium bahamense*,* Gonyaulax

the sea surface to 2,000 meters using a new photometric device. Limnol. Oceanogr.

Coastal and Estuarine Studies, XIII. Eppley, R.W.(ed.), Springer-Verlag, Berlin, 373

Falkowski, P. (ed.) Primary Productivity in the Sea, Brookhaven Symposium

Niiler, P.P., Schwing, F.B., Veit, R.R., Venrick, E.L. (1996). The state of the California Current in 1995: Continuing declines in macrozooplankton biomass

biologically important substances in a profile off southern California. Limnol.

Bioavailability and the implication for phytoplankton production, International Conference on Shellfish Restoration, South Carolina Sea Grant, Hilton Head, South

Southern California Bight bioluminescence is similar to that found in coastal waters of Vestfjord, Norway (Lapota 1990, unpublished), and the Arabian Sea (Lapota & Rosenberger 1990), but higher than that found in the Sargasso Sea (Batchelder & Swift 1989), the North Atlantic (Neilson et al. 1995) and the Beaufort Sea (Lapota et al. 1992). The vertical structure of bioluminescence was correlated with Chl fluorescence for some of the stations in the Bight. However, integrations between bioluminescence and chlorophyll were positively correlated, but weak. Strong positive correlations between bioluminescence and chlorophyll fluorescence were observed during the red tide in February 1995. At depth, seawater temperature correlated strongly with the vertical distribution of bioluminescence, as did transmission. In contrast, weaker correlations were observed between bioluminescence and Chl fluorescence. Other studies have infrequently observed correlations which may be dependent on the season the study was conducted (Lapota et al. 1989 Young et al. 1992, Neilson et al. 1995, Ondercin et al. 1995). An obvious conclusion is that the primary dinoflagellates which are contributing much of the bioluminescence do not contain Chl *a*. These would include the heterotrophic *Protoperidinium* dinoflagellates. These dinoflagellates produce as much as 30 times more light per cell than does *G. polyedra* (Biggley 1969, Lapota et al. 1992). This could explain the poor correlations between bioluminescence and chlorophyll. Consequently, these results impact models predicting bioluminescence from global ocean primary production and ocean color (Young et al. 1992, Ondercin 1995) since these are based on the assumption that much of the oceanic bioluminescence is derived from photosynthetic bioluminescent dinoflagellates (Ondercin 1995). It is clear that from this and other studies (Lapota et al. 1989, 1992,1993 a, b, Swift et al. 1995, Neilson et al. 1995 ) that *Protoperidinium* dinoflagellates dominate surface water bioluminescence in the world's oceans for a significant portion of the year.

#### **5. Acknowledgements**

We gratefully acknowledge support by the Office of Naval Research, VA through program element 0601153N-03102 and the Naval Space and Warfare Systems Center, Pacific, CA and Dr. James Case at the University of California, Santa Barbara for his guidance throughout this study. We also thank Connie H. Liu and Joel Guerrero (Naval Space and Warfare Center, Pacific for conducting chlorophyll and chemical analyses and participation in the cruises.

#### **6. References**


Southern California Bight bioluminescence is similar to that found in coastal waters of Vestfjord, Norway (Lapota 1990, unpublished), and the Arabian Sea (Lapota & Rosenberger 1990), but higher than that found in the Sargasso Sea (Batchelder & Swift 1989), the North Atlantic (Neilson et al. 1995) and the Beaufort Sea (Lapota et al. 1992). The vertical structure of bioluminescence was correlated with Chl fluorescence for some of the stations in the Bight. However, integrations between bioluminescence and chlorophyll were positively correlated, but weak. Strong positive correlations between bioluminescence and chlorophyll fluorescence were observed during the red tide in February 1995. At depth, seawater temperature correlated strongly with the vertical distribution of bioluminescence, as did transmission. In contrast, weaker correlations were observed between bioluminescence and Chl fluorescence. Other studies have infrequently observed correlations which may be dependent on the season the study was conducted (Lapota et al. 1989 Young et al. 1992, Neilson et al. 1995, Ondercin et al. 1995). An obvious conclusion is that the primary dinoflagellates which are contributing much of the bioluminescence do not contain Chl *a*. These would include the heterotrophic *Protoperidinium* dinoflagellates. These dinoflagellates produce as much as 30 times more light per cell than does *G. polyedra* (Biggley 1969, Lapota et al. 1992). This could explain the poor correlations between bioluminescence and chlorophyll. Consequently, these results impact models predicting bioluminescence from global ocean primary production and ocean color (Young et al. 1992, Ondercin 1995) since these are based on the assumption that much of the oceanic bioluminescence is derived from photosynthetic bioluminescent dinoflagellates (Ondercin 1995). It is clear that from this and other studies (Lapota et al. 1989, 1992,1993 a, b, Swift et al. 1995, Neilson et al. 1995 ) that *Protoperidinium* dinoflagellates dominate surface water bioluminescence in the world's

We gratefully acknowledge support by the Office of Naval Research, VA through program element 0601153N-03102 and the Naval Space and Warfare Systems Center, Pacific, CA and Dr. James Case at the University of California, Santa Barbara for his guidance throughout this study. We also thank Connie H. Liu and Joel Guerrero (Naval Space and Warfare Center, Pacific for conducting chlorophyll and chemical analyses and participation in the

American Public Health Association (1981). Standard methods for the examination of water

Anderson, G.C.(1964). The seasonal and geographic distribution of primary productivity off

Armstrong, F.A.J., Stearns, C.R., Strickland, J.D.H. (1967) The measurement of upwelling

Bakun, A. (1973). Coastal upwelling indices, west coast of North America, 1946-71, Nat.

Batchelder, H.P., Swift, E. (1989). Estimated near-surface mesoplanktonic bioluminescence in the western North Atlantic during July 1986. Limnol. Oceanogr. 34: 113-128.

and subsequent biological processes by means of the Technion Autoanalyser® and

the Washington and Oregon Coasts. Limnol. Oceanogr. 9: 284-302.

Oceanic Atmos. Adm. (US), Spec. Sci. Rep.- Fish No. 671, 103 pp.

and wastewater, 15th ed. Washington, D.C., 1134 pp.

associated equipment. Deep-Sea Res.14: 381-389.

oceans for a significant portion of the year.

**5. Acknowledgements** 

cruises.

**6. References** 


**2** 

David Lapota

*USA* 

**Seasonal Changes of Bioluminescence in** 

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,

Despite strong interest in short term process effects on dinoflagellates there have been few investigations on the seasonality of marine bioluminescence (Tett 1971; Bityukov et al. 1967; Lapota et al. 1997). Long term aspects of the development of bioluminescence are unknown for most oceans. The present study was designed to cast light on this question. A station for

**1. Introduction** 

1995).

**Dinoflagellates at San Clemente Island** 

**Photosynthetic and Heterotrophic** 

*Space and Naval Warfare Systems Center, Pacific* 

