Bioluminescence in a complex coastal environment: 1. Temporal dynamics of nighttime water-leaving radiance

Nighttime water-leaving radiance is a function of the depth-dependent distribution of both the in situ bioluminescence emissions and the absorption and scattering properties of the water. The vertical distributions of these parameters were used as inputs for a modified one-dimensional radiative transfer model to solve for spectral bioluminescence water-leaving radiance from prescribed depths of the water column. Variation in the water-leaving radiance was consistent with local episodic physical forcing events, with tidal forcing, terrestrial runoff, particulate accumulation, and biological responses influencing the shorter timescale dynamics. There was a \u3e90 nm shift in the peak water-leaving radiance from blue (~474 nm) to green as light propagated to the surface. In addition to clues in ecosystem responses to physical forcing, the temporal dynamics in intensity and spectral quality of water-leaving radiance provide suitable ranges for assessing detection. This may provide the information needed to estimate the depth of internal light sources in the ocean, which is discussed in part 2 of this paper

Noctiluca sp. bioluminescence in response to the mechanical stimuli of a screw propeller

This work presents a new experiment method studying the Noctiluca sp. bioluminescence under the mechanical stimulation. It devoted to the study of the Noctiluca sp. bioluminescence triggered by the screw propeller’s mechanical stimuli in the tank. The size of the tank was 2*1*1m. The screw propeller is fixed on a shelf and the position relative to the tank was adjustable by moving the shelf. Two methods were carried out to control the running of the screw propeller. In the first scenario, the shelf was fixed in the center of the tank and the second scenario, the shelf moved from one side to the other in the tank. At the same time, the screw propeller was running with a certain velocity. The luminescent strength of Noctiluca sp. enhanced as the increase of the screw propeller’s running velocity. There were two obvious luminous areas nearby the screw propeller’s blades. The luminescent area was bigger in the second scenario. Thus, when navigational ship passing the sea area which filled with Noctiluca sp. or other luminescent halobios, it will stimulate the Noctiluca sp. or other luminescent halobios bioluminescence. The ship also can be detected using the bioluminescence

Bioluminescence of the Dinoflagellate Pyrocystis noctiluca induced by laminar and turbulent couette flow

The excitation of bioluminescence by different flow regimes generated within a Couette chamber was examined using the dinoflagellates Pyrocystis noctiluca. Cultured cells of P. noctiluca were gently transferred into a cylindrical Couette chamber in a dark room. In initial experiments, the velocity of the outer Couette cylinder was then gradually increased. The bioluminescence emissions in response to stationary-laminar and turbulent flows were quantified using a photomultiplier tube. Video images were also recorded in order to identify the location of bioluminescence emissions within the Couette chamber. Reflective flake flow visualizations were used to correlate these locations to the flow regimes in those parts of the chamber. These experiments clearly demonstrated that the strongest bioluminescence emissions were only triggered by the onset of turbulence at high rotation speeds. Below the turbulence threshold, much lower bioluminescence emissions were detected and appeared to be in response to a nonhomogeneity in the stationary-laminar flow (end cap effects and Ekman cells). In a second set of experiments, the excitation of bioluminescence in response to acceleration was studied by abrupt starts of the rotating Couette cylinder. These experiments also triggered massive bioluminescence emissions. We conclude that pure laminar-stationary, homogenous shear flow excites very little bioluminescence in P. noctiluca. The bulk of bioluminescence emissions primarily occurred under nonhomogenous or nonstationary flow conditions, where the cells experience velocity changes as they move through the flow. These findings are discussed in relation to the theory that bioluminescence in dinoflagellates is an antipredation mechanism

Planktonic bioluminescence measurements in the frontal zone of Almeria-Oran (Mediterranean Sea)

Plankton bioluminescence measurements were made in the Almeria-Oran frontal zone during December 1997 and January 1998. Vertical profiles of bioluminescence, chlorophyll fluorescence, temperature and salinity were obtained using a bathyphotometer associated with a CTD (conductivity-temperature-depth) probe on a rosette. The first leg of the cruise was a regular sampling along a cross section of the area. The second leg consisted of a repetitive sampling of twelve stations at each one of the eight sites located in different water masses. Hydrological data allowed a distinction from north to south of three different water masses: Mediterranean, frontal and Atlantic. The continuous sampling indicated an increased bioluminescence in the frontal zone, with high values in the surface water and numerous light emissions as deep as 200 m. Mediterranean waters are characterized by an intense bioluminescence in the first 50 m with a maximum just above the thermocline and a few bioluminescent flashes above, whereas bioluminescence in Atlantic waters is evenly distributed from the surface to 130 m depth with no strong maxima. Inter-site bioluminescence variability is much greater than intra-site, demonstrating that bioluminescence profiles clearly reflect differences between hydrological areas. Bioluminescence is correlated with fluorescence at three out of the eight sites, suggesting a relative importance of chlorophyllian bioluminescent organisms. No direct correlation with temperature and salinity has been demonstrated, however, the thermocline is nearly always accompanied by an increased bioluminescent activity.Des mesures de bioluminescence planctonique ont été réalisées dans la zone du front Almeria–Oran en décembre 1997 et en janvier 1998. Des profils verticaux de bioluminescence, de fluorescence de la chlorophylle, de température et de salinité ont été obtenus avec un bathyphotomètre couplé à une sonde CTD (conductivity–temperature–depth) et à un fluorimètre. La première partie de la mission consistait en un échantillonnage régulier le long d’une radiale transversale au front. Au cours de la seconde partie, un échantillonnage répétitif de douze stations sur huit sites correspondant à différentes masses d’eau caractéristiques de la zone frontale a été effectué. Les données hydrologiques permettent de distinguer trois aires marines du nord au sud : « méditerranéenne », frontale et « atlantique ». L’échantillonnage en continu indique une augmentation de la bioluminescence dans la zone frontale, avec de fortes valeurs en surface et de nombreuses émissions lumineuses jusqu’à 200 m de profondeur. Les eaux méditerranéennes sont caractérisées par une stratification de la bioluminescence qui présente des valeurs intenses dans les 50 premiers mètres et maximales juste au dessus de la thermocline, tandis que la bioluminescence des eaux atlantiques est régulièrement distribuée dans la couche de mélange, entre la surface et 130 m de profondeur. Les profils de bioluminescence indiquent une variabilité inter-sites supérieure à la variabilité intra-sites et reflètent les différences de structures hydrologiques entre les sites. La bioluminescence et la fluorescence sont corrélées à trois des huit sites, suggérant une relative importance d’organismes chlorophylliens bioluminescents. Aucune corrélation directe entre la bioluminescence et la température ou la salinité n’a été mise en évidence, mais la thermocline est, dans de nombreux cas, accompagnée d’une augmentation de l’activité lumineuse

Variability in the bioluminsecence response of the dinoflagellate Pyrocystis lunula

International audienceLight emission in dinoflagellates is induced by water motions. But although it is known that mechanical stimulations of these organisms trigger the bioluminescent response, the exact mechanism that involves some cell membrane excitations by fluid motions is not yet fully understood and is still controversial. We show in this experimental study that the accelerated shear flow, created by abrupt rotations of one or both co-axial cylinders of a Couette shearing chamber excites the light emission from cultured dinoflagellates Pyrocystis lunula. Following our first results published earlier that state that pure laminar shear does not excite the main bioluminescent response in dinoflagellates, our present experiments show that both shear and acceleration in the flow are needed to trigger the bioluminescent response. Besides, the probability to stimulate this bioluminescent response under acceleration and shear is deduced from the response curves. This response follows a Gaussian distribution that traduces an heterogeneity in individual cell thresholds for the stimulation of bioluminescence in a dinoflagellate population. All these results will have a repercussion in the possible applications of dinoflagellate bioluminescence in flow visualizations and measurements. Moreover, this study opens a new way in studying mechanically-induced stimulus thresholds at the cell level

Observations of in situ deep-sea marine bioluminescence with a high-speed, high-resolution sCMOS camera

Observing and measuring marine bioluminescence in situ presents unique challenges, characterized by the difficult task of approaching and imaging weakly illuminated bodies in a three-dimensional environment. To address this problem, a scientific complementary-metal-oxide-semiconductor (sCMOS) microscopy camera was outfitted for deep-sea imaging of marine bioluminescence. This system was deployed on multiple platforms (manned submersible, remotely operated vehicle, and towed body) in three oceanic regions (Western Tropical Pacific, Eastern Equatorial Pacific, and Northwestern Atlantic) to depths up to 2500 m. Using light stimulation, bioluminescent responses were recorded at high frame rates and in high resolution, offering unprecedented low-light imagery of deep-sea bioluminescence in situ. The kinematics of light production in several zooplankton groups was observed, and luminescent responses at different depths were quantified as intensity vs. time. These initial results signify a clear advancement in the bioluminescent imaging methods available for observation and experimentation in the deep-sea

Molecular detection of bioluminescent dinoflagellates in surface waters of the Patagonian Shelf during early austral summer 2008

We investigated the distribution of bioluminescent dinoflagellates in the Patagonian Shelf region using “universal” PCR primers for the dinoflagellate luciferase gene. Luciferase gene sequences and single cell PCR tests, in conjunction with taxonomic identification by microscopy, allowed us to identify and quantify bioluminescent dinoflagellates. We compared these data to coincidental discrete optical measurements of stimulable bioluminescence intensity. Molecular detection of the luciferase gene showed that bioluminescent dinoflagellates were widespread across the majority of the Patagonian Shelf region. Their presence was comparatively underestimated by optical bioluminescence measurements, whose magnitude was affected by interspecific differences in bioluminescence intensity and by the presence of other bioluminescent organisms. Molecular and microscopy data showed that the complex hydrography of the area played an important role in determining the distribution and composition of dinoflagellate populations. Dinoflagellates were absent south of the Falkland Islands where the cold, nutrient-rich, and well-mixed waters of the Falklands Current favoured diatoms instead. Diverse populations of dinoflagellates were present in the warmer, more stratified waters of the Patagonian Shelf and Falklands Current as it warmed northwards. Here, the dinoflagellate population composition could be related to distinct water masses. Our results provide new insight into the prevalence of bioluminescent dinoflagellates in Patagonian Shelf waters and demonstrate that a molecular approach to the detection of bioluminescent dinoflagellates in natural waters is a promising tool for ecological studies of these organisms