Turbulent length scales have also been considered important parameters for bioluminescence stimulation (Anderson et al., 1988; Widder et al., 1993; Latz et al., 1994; Rohr et al., 1997). It may be also useful for mapping highly dissipative oceanic flows (Rohr et al., 2002). Non-bioluminescent dinoflagellates were generally present at much higher abundances across the Patagonian Shelf than bioluminescent dinoflagellates (Figure 7). It is no doubt that bioluminescent dinoflagellates are of marine origin and their life cycle is bounded within the sea. By definition, fully developed pipe flow cannot determine the sensitivity of dinoflagellate cells in developing flows, an issue which must be addressed in a different flow field (von Dassow, 2003). 7). Representative time series of bioluminescence of (A) Ceratium fusus, (B) Ceratocorys horrida, (C) Lingulodinium polyedrum and (D) Pyrocystis fusiformis in laminar flows with wall shear stress ≈0.4 N m−2, demonstrating considerable differences in response among species. Changes in the morphology and swimming of C. horrida occur after 1 h of agitation on an orbital shaker where average shear stress values were an order of magnitude less than bioluminescence threshold values (Zirbel et al., 2000). The length scales of the turbulence ranged from the radius of the pipe (Davies, 1972) to of the order of 10 μm. Only for C. fusus was there a significant increase in maximum intensity. Search for other works by this author on: In fully developed laminar and turbulent pipe flow, shear stress is greatest at the pipe wall and decreases linearly to zero at the pipe centerline. Pyrocystis Fusiformis is a dinoflagellate that has the ability to makes its light through a metabolic process involving oxidation of luciferin. Dinoflagellate bioluminescence provides a nearly instantaneous index of flow sensitivity. The intensity and regularity of sunlight are uncertain, so these grow lamps will ensure to give the dinoflagellates enough sunlight. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide, This PDF is available to Subscribers Only. The order in which the pooled data of maximum intensity of each species reached a plateau with increasing wall shear stress was C. horrida (∼0.1 N m−2), P. fusiformis (1 N m−2), L. polyedrum (2 N m−2) and C. fusus (2.5–6 N m−2). A shear stress of 1 N m−2 may be more representative of the population for these species because at this level a few percentage of the cells were observed to flash. Flow sensitivity is affected by the thickness and chemical composition of the cell wall (Namdev and Dunlop, 1995). (, Biggley, W. H., Swift, E., Buchanan, R. J. et al. Lunula is the topographic Laboratory cultures of C. fusus Ehrenb, C. horrida Stein [strain 89A from the Sargasso Sea, see (Latz and Lee, 1995)] and P. fusiformis Murray were grown in seawater with f/2 additions at half strength (Guillard and Ryther, 1962) minus silicate as previously described (Latz and Rohr, 1999) on a 12:12 h light–dark cycle. Threshold values of wall shear stress were 0.116 ± 0.02 N m−2 for C. fusus, 0.024 ± 0.009 N m−2 for C. horrida and 0.087 ± 0.02 N m−2 for P. fusiformis. Based on the species selected, it is not possible to draw conclusions about the role of thecae in shear sensitivity. (A) Ceratium fusus, y = 7.63 × 1011x0.51, r2 = 0.554, (B) Ceratocorys horrida, y = 6.32 × 1014 x2.10, r2 = 0.44 for flows with wall shear stresses <0.1 N m−2; y = 7.92 × 1012 x−0.18, r2 = 0.0944 for flows with wall shear stresses >0.1 N m−2, (C) Lingulodinium polyedrum, y = 1.89 × 1012 x2.40, r2 = 0.719 and (D) Pyrocystis fusiformis, y = 5.79 × 1013 x2.02, r2 = 0.760. However, measurements of average intensity are often expressed per unit volume [i.e. The detector was coupled to the pipe using a light-shielded adapter and viewed a 0.05-m length of pipe and its entire width. The difference for P. fusiformis was barely significant (t = 2.1, df = 30, P = 0.05) and the differences for L. polyedrum and C. horrida were not significant (t = 1.0, df = 25, P = 0.3; t = 1.7, df = 27, P = 0.1 respectively). Even considering the length of its spines, the overall length of C. horrida cells was less than that of P. fusiformis, which was less sensitive despite being larger. Anderson, D. M., Nosenchuck, D. M., Reynolds, G. T. et al. Although C. fusus has a cosmopolitan distribution, ranging from oceanic to estuarine habitats, it is principally a coastal species (Sullivan and Swift, 1995) and has a deeper vertical distribution than L. polyedrum (Lapota et al., 1989; Swift et al., 1995). The photon flux of individual flashes of C. fusus and P. fusiformis was measured to allow comparison with previous measurements for the other species. Therefore, the actual value of stimulatory shear stress for pipe flow may be less than that stated for wall shear stress and more similar to that obtained in Couette flow. Consequently, for the same cell morphology, the stimulatory nature of laminar and turbulent flow may be significantly different. It is well known that surface breaking waves stimulate bioluminescence (Staples, 1966; Latz et al., 1994) as do bottom shears created by passing waves in a laboratory wave tank (M. I. Latz and J. Rohr, personal observations). This may reflect the ability of this species to respond to low-intensity stimuli with submaximal flashes localized to the area of the cell that is directly stimulated (Widder and Case, 1982). Average intensity, expressed as photons m−3 (Fig. (, Seliger, H. H., Biggley, W. H. and Swift, E. (, Stokes, M. D., Deane, G. B., Latz, M. I. et al. Once the required Dinoflagellate red tides are caused by numerous marine/estuarine species such as the “Florida red tide” dinoflagellate Karenia, or Alexandrium blooms, which cause … Symbols represent individual values from the pooled set of experiments for each species for laminar (solid) and turbulent (open) flows. The container has to be transparent which allows proper distribution of sunlight. Unless otherwise stated, values represent means with standard deviations of the mean from this data set. The line represents the least-squares power regression of average intensity as a function of wall shear stress in laminar flow. The slightly greater threshold values obtained in pipe flow may be due to the lower cell concentration, which will result in a higher response threshold (Latz and Rohr, 1999). One criterion for flow sensitivity in this study is the population response proportion at the shear stress response threshold. The substrate of the light-producing biochemical reaction is luciferin. Pyrocystis fusiformises lose their flagella as they mature and are thus non-motile dinoflagellates with tapering ends. These species offer an interesting comparison because of their interspecific range in cell size (equivalent spherical diameter = 40–340 μm), cell shape (fusiform, spherical and spined) and the possession or absence of thecae, which are rigid polysaccharide plates comprising the cytoskeleton (Fig. Laminar flow-stimulation studies for P. fusiformis in Couette flow (Latz et al., 1994) and C. horrida in converging nozzle flow (Latz et al., 2004) suggest that both these species are more flow sensitive than L. polyedrum. These unicellular dinoflagellates are spherical and are about 200-400 micrometers in size. Consequently, extended bioluminescence time series can be obtained during constant flow conditions, without the problem of exhausting luminescent capacity. The life span of dinoflagellate depends on the amount of sunlight it receives but the average lifespan is about 2-4 months. The presence of spines may also result in increased flow sensitivity (Zirbel et al., 2000) because the spines could act as levers, accentuating the fluid shear around the cell at the base of the spine. Population response proportion measurements were restricted to laminar flows with wall shear stress values <1.5 N m−2, where flash coincidence did not occur. Average values of threshold wall shear stress were calculated for each species based on values for replicate experiments. Cells were loaded into the head tank of the pipe-flow apparatus at the end of the light phase of the growth light–dark cycle when sensitivity to mechanical stimulation is minimal. In the sea, light emission by these unicellular organisms is mostly seen when cells are mechanically stimulated, at the surface of waves, in breakers, by swimming animals or humans or by vessels. The relatively high intraspecific variation in threshold values from different experiments for C. fusus and P. fusiformis resulted in a lack of statistically significant difference between their thresholds. This species of dinoflagellate is very beautiful but is usually very tricky to grow. Minimum values of the population response proportion (i.e. The population response proportion was 0.0012 flashes cell−1 for C. fusus, 0.0264 flashes cell−1 for C. horrida, 0.0003 flashes cell−1 for L. polyedrum and 0.0010 flashes cell−1 for P. fusiformis (Fig. In turbulent flow, the larger the organism relative to the energetic scales of the turbulence, the more effective the turbulence is at deformation (Levich, 1962). For the pipe-flow experiments, the shear exposure time, based on average flow rates, is between 20 s at near threshold flows and 0.4 s at the highest flow rates (Latz and Rohr, 1999). It commonly produces blue light in response to movements or disturbances in the water which can be usually accounted to waves, animals, or ships. The container should be lidded. Maximum intensity is the brightest 0.005 s flash event in a data record obtained for a constant flow rate. Flashes serve as visible ‘burglar alarms’ to attract secondary predators, increasing the risk of predation to the dinoflagellate grazer (Burkenroad, 1943; Morin, 1983). Some of the most common species of Bioluminescent Dinoflagellates that can be grown at home are: 1. Maximum intensity increased as a function of suprathreshold levels of wall shear stress, approaching a nearly constant level (Fig. For a Q = 0.279 mL s−1, a shear stress of 1 N m−2 occurs at r = 0.36 mm, essentially within the 0.25 mm capture volume of a copepod (Kiørboe et al., 1999). For freshly collected cells from the north Atlantic during August 1991. Your email address will not be published. Bioluminescence is the characteristic feature of dinoflagellates. Photomultiplier measurements in units of counts s−1 were converted to photons s−1 using a previously described calibration procedure (Latz and Rohr, 1999). 2. The accelerations within this range are from 0.31 to 25 m s−2 and are not considered to be stimulatory (Latz et al., 2004). (, 1Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0202, USA and 2Spawar Systems Center San Diego, 53560 Hull Street, 211, San Diego, CA 92152-5001, USA, Oxford University Press is a department of the University of Oxford. For example, only the energy associated with turbulent length scales smaller than the size of drops or bubbles is available to cause splitting as opposed to transport (Clift et al., 1978). Pyrocystis sp. The lights startle the predators and also attract high trophic level organisms that feed on dinoflagellate’s predators. At the highest laminar flow rates, the population response proportion varied among species by less than an order of magnitude. 1993). Maximum intensity, an index of the peak intensity of an individual flash, was determined by taking the highest 0.005 ms value in each time series record. These single-celled organisms are common members of the plankton—tiny marine plants, animals or bacteria that float on or near the ocean’s surface. At double the flow rate (0.559 cm s−1, thick dashed line), Rcritical is greater but occurs at the identical shear stress level. The timing of light on and light off should be strictly followed. A similar pattern of flash intensity for L. polyedrum and P. fusiformis has been observed in laminar pipe and Couette flows respectively (Latz et al., 1994; Latz and Rohr, 1999). (, Kamykowski, D., Reed, R. E. and Kirkpatrick, G. J. Bioluminescent Dinoflagellates. Non-marine bioluminescence is less widely distributed.The two best-known forms of land bioluminescence are fireflies and glow worms. A. The larger uncertainty for C. fusus is because transition to turbulence occurred when maximum intensity began to plateau. Previous studies of flow-stimulated bioluminescence using unialgal cultures (Latz et al., 1994; Latz and Rohr, 1999) or freshly collected seawater samples in which dinoflagellates were the primary luminescent organisms (Rohr et al., 1994, 2002) have shown that the response is correlated with wall shear stress. Using threshold values of shear stress of C. fusus, L. polyedrum and P. fusiformis for determining flash position relative to the predator may be too conservative. Values represent mean ± standard deviation; the range of values is given in parentheses. Thus, mechanical stimulation of dinoflagellate bioluminescence is ecologically important not only in the context of predator interactions with dinoflagellate cells but also as a ‘mine field’ that potentially increases the risk of predation to moving animals. Whether cells with these attributes have an antipredation advantage has yet to be proven but is an attractive hypothesis. (, Vanderploeg, H. A. and Paffenhöfer, G. A. Average intensity, expressed as photons m−3 to account for advective effects, as a function of wall shear stress for suprathreshold flows. The only difference is that maximum intensity for C. fusus appeared to level off at slightly higher wall shear stress levels than for L. polyedrum. Suspension feeders such as copepods capture organisms by movement of the second maxillae to direct particles from the feeding current toward the mouth (Koehl and Strickler, 1981; Vanderploeg and Paffenhöfer, 1985; Price and Paffenhöfer, 1986) where they are macerated by the mandibles (Arashkevich, 1969). Average flow speed was determined by dividing the mass of water collected over a measured time by the cross-sectional area of the pipe. Flow-stimulated dinoflagellate bioluminescence can also serve as a ‘luminescent mine field’ (Young, 1983), in that animals are outlined by the light stimulated by their swimming (Hobson, 1966; Rohr et al., 1998), enhancing the ability of visual nocturnal predators to locate prey (Mensinger and Case, 1992; Fleisher and Case, 1995). 7). Fully developed pipe flow was chosen as the experimental flow field because (i) the flow field can be fully characterized in terms of shear stress by simple measurements of volumetric flow and pressure drop, (ii) laminar and turbulent flows with a wide range of shear stresses can be generated, (iii) new organisms are constantly entering the flow field, to minimize potential problems with depletion of bioluminescence, and (iv) the organisms experience the flow field for only a short time. Images were obtained using phase optics. The bioluminescence response threshold occurred in laminar flow for all species examined. After cleaning and drying the container, the next step is to pour an inch of algae growth solution and a few inches of the dinoflagellate culture. Dinoflagellate produces this light through metabolizing luciferin and light up water bodies as a defense mechanism. 4). Some species are parasites on algae, zooplankton, fish or other organisms. 6) to account for advective affects in fully developed, laminar pipe flow, is expected to exhibit a decreased dependence on wall shear stress. (, Huntley, M. E., Sykes, P., Rohan, P. et al. Four replicate experiments were performed for each species, except for L. polyedrum where data were obtained from six previous experiments (Latz and Rohr, 1999). This study, which uses fully developed pipe flow, provides the first quantitative examination of the laminar flow response of C. fusus and C. horrida and the turbulent flow response of C. fusus, C. horrida and P. fusiformis. 3. Shear stress in siphon flow, representing a predator feeding current, as a function of distance from the siphon mouth. Its highest maximum flash intensity occurred near the response threshold, whereas for the other species the highest maximum flash intensity occurred at wall shear stress levels an order of magnitude greater than threshold. 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