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|Bioluminescence response of four species of dinoflagellates to fully developed pipe flow|
|Latz, M.I.; Nauen, J.C.; Rohr, J. (2004). Bioluminescence response of four species of dinoflagellates to fully developed pipe flow. J. Plankton Res. 26(12): 1529-1546. dx.doi.org/10.1093/plankt/fbh141|
|In: Journal of Plankton Research. Information Retrieval Ltd.: London. ISSN 0142-7873, more|
Bioluminescence; Dinoflagellata [WoRMS]; Marine
Dinoflagellate bioluminescence provides a nearly instantaneous index of flow sensitivity. This study compared flow sensitivity in four species of morphologically diverse luminescent dinoflagellates (Ceratium fusus, Ceratocorys horrida, Lingulodinium polyedrum and Pyrocystis fusiformis) using fully developed laminar and turbulent pipe flow. Bioluminescence response thresholds always occurred in laminar flows with wall shear stress levels that, depending on species, ranged from 0.02 to 0.3 N m-2. With few exceptions, such as breaking waves and wave-forced bottom shears in shallow nearshore areas, these threshold shear stress levels are several orders of magnitude larger than typical oceanic ambient flows. For laminar flows above threshold, species also differed in the proportion of organisms responding and the minimum shear stress level where individual flashes reached their highest intensity. Following transition to turbulent flow, there was never a dramatic increase in bioluminescence, even when energetic turbulent length scales were similar to the cell size. On the basis of their bioluminescence response in laminar flow, these species were ranked in order of decreasing sensitivity as C. horrida > P. fusiformis > C. fusus > L. polyedrum. This ranking, though not conclusive, is consistent with increased flow sensitivity due to increasing size and the presence of spines. With the exception of a small fraction of the C. horrida population that is sensitive enough to flash within the feeding current of a predator, the present study suggests that flashes only occur with predator contact. Nevertheless, flow sensitivity may serve as an index of the response to mechanical agitation during predator contact/handling. Flow sensitivity may be constrained to maximize the response to predator contact/handling while minimizing stimulation by background oceanic flows to avoid depleting luminescent reserves.