Avoidance, movement, and mortality: The interactions between a protistan grazer and <i>Heterosigma akashiwo</i>, a harmful algal bloom species

Harvey, Elizabeth L.; Menden‐Deuer, Susanne

doi:10.4319/lo.2011.56.1.0371

Cited by 34 publications

(28 citation statements)

References 35 publications

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“…Directionality of movement tracks was measured by comparing the swimming direction of the krill relative to horizontal. Turning rates were measured as changes in swimming directionality over time (e.g., Harvey and Menden‐Deuer ). Krill lengths were measured from krill collected by the MOCNESS tows of the late austral autumn and ranged between 9 and 51 mm, with an average of 29 mm (Cleary et al ).…”

Section: Methodsmentioning

confidence: 99%

Krill motion in the Southern Ocean: quantifying in situ krill movement behaviors and distributions during the late austral autumn and spring

Kane

Yopak

Roman

et al. 2018

Limnology & Oceanography

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Krill movement behaviors and vertical distributions were measured in spring and autumn using a profiling stereo‐camera and environmental sensor system to quantify seasonal changes in the role of krill in Southern Ocean food webs. Krill were observed in May–June 2013 and December 2014 in 3 bays in the Western Antarctic Peninsula. Krill abundances and movement behaviors were determined from in situ image sequences collected for up to 10 min throughout the water column, up to 625 m deep; 3,345 individual krill tracks were collected. Seasonal changes in individual krill behaviors coincided with seasonal shifts in krill vertical distributions. During late spring, net upward swimming direction (0.9 ± 2.1° from horizontal) and vertical velocity (0.3 ± 0.2 body lengths [BL] s−1) resulted in shallower maximum abundances of krill within the water column proximate to near‐surface phytoplankton distributions. During late autumn, krill swimming patterns tended downward, including swimming direction (−5.2 ± 0.8° from horizontal) and vertical velocity (−0.1 ± 0.0 BL s−1), leading to deeper distributions proximate to the benthos. Individual krill motility was greater in spring than autumn, as evidenced by an increase in swimming speeds (5.4 ± 0.2 vs. 2.8 ± 0.0 BL s−1) and turning rates (120 ± 5 vs. 107 ± 2° s−1). Remarkably, krill in autumn were capable of swimming as quickly as krill in spring. These results suggest seasonal shifts in krill movement behaviors have direct ramifications for krill distributions, proximity to food sources, and impacts on biogeochemical cycling in coastal Antarctic waters.

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Section: Methodsmentioning

confidence: 99%

Krill motion in the Southern Ocean: quantifying in situ krill movement behaviors and distributions during the late austral autumn and spring

Kane

Yopak

Roman

et al. 2018

Limnology & Oceanography

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“…[11] 3D swimming paths were determined by first assembling 2D trajectories from Cartesian coordinates of each organism in each stereoframe and then joining 2D tracks based on matching space–time occurrence in the two 2D segments. To reduce spurious noise, the 3D paths were smoothed using cubic splines in each dimension and resampled at the filming rate (every 0.07 s) for subsequent RMSD analysis (for more details, see Menden‐Deuer and Grünbaum 2006; Harvey and Menden‐Deuer 2011).…”

Section: Methodsmentioning

confidence: 99%

Going ballistic in the plankton: Anisotropic swimming behavior of marine protists

Schuech

Menden‐Deuer

2014

Limn Fluids and Environments

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Diel vertical migrations (DVMs) of many plankton species, including single-celled protists, are well documented in the field and form a core component of many large-scale numerical models of plankton transport and ecology. However, the sparse quantitative data available describing motility behaviors of individual protists have frequently indicated that motility exhibits only short-term correlation on the order of a few seconds or hundreds of micrometers, resembling diffusive transport at larger scales-a result incompatible with DVM, which requires ballistic (straight-line) motion. We interrogated an extensive set of three-dimensional protistan movement trajectories in an effort to identify spatial and temporal correlation scales. Whereas the horizontal components of movement were diffusive, the vertical component remained highly correlated (i.e., nonrandom) for nearly all species for the duration of observation (up to 120 s and 6.1 mm) and in the absence of any environmental cues besides gravity. These persistent motility patterns may have been obscured in some previous studies due to the use of restrictive containers, dimensionally lumped, isotropic analyses, and/or an observation bias, inherent to observing free-swimming organisms with stationary cameras, which we accounted for in this study. Extrapolated over a 12-h period, conservative estimates of vertical travel ranges for the protists observed here would be 3-10 m, while diffusive horizontal motion would result in about 10 cm of travel at most. Hence, these extended observations of phylogenetically diverse swimming protists, coupled with a quantitative analysis that accounts for anisotropy in the data, illustrate the small-scale mechanistic underpinnings of DVM.

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“…In response to the presence of S. algicida filtrate, H. akashiwo dramatically increased swimming speed in the vertical direction, resulting in an accumulation of algae in a predator filtrate-free portion of the tank and a reduction in encounter rate. This fleeing behavior was recently shown to result in significant increases in population growth rate in a different strain of H. akashiwo in response to a ciliate predator (Harvey and Menden-Deuer 2012). Such avoidance behaviors contribute to driving shifts in the distribution and local abundance of this toxic alga, and could ultimately modulate bloom formation in this species (Strom et al 2013).…”

Section: Discussionmentioning

confidence: 99%

Avoidance and attraction: Chemical cues influence predator‐prey interactions of planktonic protists

Harvey

Jeong

Menden‐Deuer

2013

Limnology & Oceanography

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We measured how predator-and prey-derived chemical cues affect swimming behaviors and encounter rates of two common phytoplankton species (Amphidinum carterae, Heterosigma akashiwo) and two heterotrophic dinoflagellate predators (Stoeckeria algicida, Gyrodiniellum shiwhaense). Using video and image analysis, the microscopic three-dimensional movement behaviors and macroscopic population distributions of the species were quantified in response to chemical cues derived from their respective predator or prey species. S. algicida preferentially feeds on H. akashiwo but displayed significant increases in swimming speed and turning rate when exposed to filtrate from either prey species. Prey cue-induced changes in predator swimming behavior resulted in an average 11% increase in encounter rate. S. algicida that respond to prey filtrate would reach their daily prey quota at a 25% lower ambient prey concentration. In contrast, G. shiwhaense, which rarely feeds and does not grow on H. akashiwo, exhibited no shifts in behavior in response to algal filtrate. Predator-derived cues from S. algicida elicited significant increases in upward motility in H. akashiwo, resulting in a shift in the prey population abundance away from the predator-derived chemical cue. These algal fleeing behaviors reduced estimated encounter rates by 4%, compared to non-fleeing behaviors. Our results provide quantitative evidence for the importance of chemical cues in modulating feeding interactions and emphasize the ramifications of individual behaviors, and modulation thereof, to population-level outcomes, including population distributions, and predation pressure.

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Avoidance, movement, and mortality: The interactions between a protistan grazer and Heterosigma akashiwo, a harmful algal bloom species

Cited by 34 publications

References 35 publications

Krill motion in the Southern Ocean: quantifying in situ krill movement behaviors and distributions during the late austral autumn and spring

Krill motion in the Southern Ocean: quantifying in situ krill movement behaviors and distributions during the late austral autumn and spring

Going ballistic in the plankton: Anisotropic swimming behavior of marine protists

Avoidance and attraction: Chemical cues influence predator‐prey interactions of planktonic protists

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