Effects of dead conspecifics, hunger states, and seasons on the foraging behavior of the purple urchin Heliocidaris crassispina

ABSTRACTTrophic cascades exerts a powerful effect between predator and prey relationships in an ecosystem. In aquatic environments, the signals associated with predators and predation are used by prey as a cue to avoid encountering predators when foraging for food. These cues are powerful enough to control prey populations and indirectly protect primary producers. We evaluated the effects of cues associated with predation on the purple urchin, Heliocidaris crassispina and examined effects of hunger state and season using time-lapse photography, we conducted a series of manipulative and in situ behavior experiments to determine foraging behavior patterns which demonstrate behavior modification. The results suggest that starved urchins were less sensitive to predation cues when compared to normally fed urchins. Field experiments indicated that 70% of fed urchins fled when exposed to a predation cue (presence of a dead urchin), whereas all starved urchins remained regardless of the cue, supporting the results from the laboratory using the dead urchin and algae treatment cues. Sea urchin activity and feeding rates were lower in winter-spring than in summer-autumn. We suggest that hunger state has a large influence over the behavioral-response of sea urchins, while also being affected by season due to metabolic control. In general, starvation overrides predator avoidance behaviors and exposes prey species to higher risks of predation.

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Effects of dead conspecifics, hunger states, and seasons on the foraging behavior of the purple urchin Heliocidaris crassispina

Marine Ecology Progress Series ◽

10.3354/meps13653 ◽

2021 ◽

Vol 664 ◽

pp. 133-148

Author(s):

DFC Belleza ◽

Y Kawabata ◽

T Toda ◽

GN Nishihara

Keyword(s):

Foraging Behavior ◽

Field Experiments ◽

Sea Urchins ◽

Time Lapse ◽

Feeding Rates ◽

Predator Prey ◽

Avoidance Behaviors ◽

Behavioral Cues ◽

Time Lapse Photography

Trophic cascades are a powerful result of predator-prey relationships in an ecosystem. In aquatic environments, the signals associated with predators and predation are used by prey as a cue to avoid encountering predators when foraging for food. These behavioral cues can be powerful enough to control prey populations and indirectly protect primary producers. Here, we evaluated the effects of cues associated with predation on the purple urchin Heliocidaris crassispina and examined effects of hunger state and season, using time-lapse photography. A series of laboratory and in situ manipulative experiments were conducted to determine patterns of foraging behavior and behavioral modifications. We showed that starved urchins were less sensitive to predation cues compared to normally fed urchins. Field experiments indicated that 70% of fed urchins fled when exposed to a predation cue (presence of a dead urchin) whereas starved urchins remained regardless of the cue, supporting results from the laboratory using dead urchin and algal cues. Sea urchin activity and feeding rates were lower in winter-spring than in summer-autumn. Results suggest that hunger state has a large influence over the behavioral response of sea urchins, while also being affected by season due to metabolic control. In general, starvation appears to override predator avoidance behaviors, which exposes prey species to higher risks of predation.

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Feeding rates of abyssal scavenging amphipods (Eurythenes gryllus) determined in situ by time-lapse photography

Deep Sea Research Part A Oceanographic Research Papers ◽

10.1016/0198-0149(85)90090-1 ◽

1985 ◽

Vol 32 (4) ◽

pp. 443-450 ◽

Cited By ~ 33

Author(s):

B.T. Hargrave

Keyword(s):

Time Lapse ◽

Feeding Rates ◽

Time Lapse Photography

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Freezing or death feigning? Beetles selected for long death-feigning duration showed other tactics against different predators

10.22541/au.163406331.16479813/v1 ◽

2021 ◽

Author(s):

Masaya Asakura ◽

Kentarou Matsumura ◽

Ryo Ishihara ◽

Takahisa Miyatake

Keyword(s):

Prey Density ◽

Prey Species ◽

Antipredator Behavior ◽

Freezing Behavior ◽

Starvation Period ◽

Feeding Rates ◽

Death Feigning ◽

Avoidance Behaviors ◽

Long Duration ◽

Independent Behaviors

Prey evolve anti-predator strategies against multiple enemies in nature. We examined how a prey species adopts different predation avoidance tactics against pursuit or sit-and-wait predators. As prey, we used two strains of Tribolium beetles artificially selected for short or long duration of death feigning. The results showed that, as prey, the short strains displayed the same behavior, escaping, against the two types of predators. On the other hand, death feigning is known to be effective for evading a jumping spider in the case of the long strains, while the present study showed that the long strain beetles used freezing behavior against a sit-and-wait type predator A. venator in this study. The short strain beetles were more easily orientated by predators and suffered a higher rate of predation than the long strains. The time to predation was also shorter in the short strains compared to the long strains. When the predator was starved, even the long strains were preyed upon when the predator was orientated toward the prey, suggesting the starvation period, i.e., prey density, is an important factor for antipredator behavior. Traditionally, death feigning has been thought to be the last resort in a series of anti-predator avoidance behaviors. However, our results showed that freezing and death feigning were not parts of a series of behavior, but independent behaviors against different predators, at least for these beetles. The results also suggest that the differences in feeding rates between the strains could be explained by differences in activity among the strains.

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Subglacial hydrology at Rink Isbræ, West Greenland inferred from sediment plume appearance

Annals of Glaciology ◽

10.1017/aog.2016.1 ◽

2016 ◽

Vol 57 (72) ◽

pp. 118-127 ◽

Cited By ~ 13

Author(s):

Kristin M. Schild ◽

Robert L. Hawley ◽

Blaine F. Morriss

Keyword(s):

Time Lapse ◽

Short Term ◽

Velocity Change ◽

Tidewater Glaciers ◽

West Greenland ◽

Meltwater Runoff ◽

Subglacial Meltwater ◽

Time Lapse Photography ◽

Frontal Ablation

ABSTRACTMarine-terminating outlet glaciers discharge most of the Greenland ice sheet's mass through frontal ablation and meltwater runoff. While calving can be estimated by in situ and remote sensing observations, submarine melting and subglacial meltwater transport are more challenging to quantify. Here we investigate the subglacial hydrology of Rink Isbræ, a fast-flowing West Greenland tidewater glacier, using time-lapse photography, modeled runoff estimates and daily satellite imagery from 2007 to 2011. We find that sediment plumes appear episodically at four distinct locations across the terminus, and last between 2 h and 17 d. This suggests short-term variability in discharge and the existence of persistent pathways. The seasonal onset of sediment plumes occurs before supraglacial lake drainages, shortly after the onset of runoff, and only after the wintertime ice mélange has begun disintegrating. Plumes were also visible after the cessation of runoff (23 ± 5 d), which is indicative of subglacial storage. The lack of either a seasonal velocity change or a correspondence between meltwater availability and plume occurrence suggests that the subglacial system persists in a state of inefficient drainage. Subglacial hydrology at tidewater glaciers is of critical importance in understanding dynamics at the ice front.

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Enhanced drag of a sphere settling in a stratified fluid at small Reynolds numbers

Journal of Fluid Mechanics ◽

10.1017/s0022112009007332 ◽

2009 ◽

Vol 632 ◽

pp. 49-68 ◽

Cited By ~ 53

Author(s):

KING YEUNG YICK ◽

CARLOS R. TORRES ◽

THOMAS PEACOCK ◽

ROMAN STOCKER

Keyword(s):

Time Lapse ◽

Reynolds Numbers ◽

Stratified Fluid ◽

Buoyancy Frequency ◽

Aquatic Environments ◽

Fluid Viscosity ◽

Vertical Fluxes ◽

Small Reynolds Numbers ◽

Density Interfaces ◽

Time Lapse Photography

We present a combined experimental and numerical investigation of a sphere settling in a linearly stratified fluid at small Reynolds numbers. Using time-lapse photography and numerical modelling, we observed and quantified an increase in drag due to stratification. For a salt stratification, the normalized added drag coefficient scales as Ri0.51, where Ri = a3N2/(νU) is the viscous Richardson number, a the particle radius, U its speed, ν the kinematic fluid viscosity and N the buoyancy frequency. Microscale synthetic schlieren revealed that a settling sphere draws lighter fluid downwards, resulting in a density wake extending tens of particle radii. Analysis of the flow and density fields shows that the added drag results from the buoyancy of the fluid in a region of size (ν/N)1/2 surrounding the sphere, while the bulk of the wake does not influence drag. A scaling argument is provided to rationalize the observations. The enhanced drag can increase settling times in natural aquatic environments, affecting retention of particles at density interfaces and vertical fluxes of organic matter.

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Experimental study of the formation of the bulboventricular loop in the chick

Development ◽

10.1242/dev.27.3.623 ◽

1972 ◽

Vol 27 (3) ◽

pp. 623-637

Author(s):

Alfredo Castro-Quezada ◽

Bernardo Nadal-Ginard ◽

María V. de la Cruz

Keyword(s):

Electron Microscope ◽

Time Lapse ◽

Mirror Image ◽

Heart Tube ◽

Removal Experiments ◽

Atrioventricular Groove ◽

The Right ◽

Time Lapse Photography ◽

Made In

The formation of the normal bulboventricular loop (convex to the right) and the inverted loop (convex to the left) produced by the Lepori technique in chick embryos was studied. The development of the loops was recorded by means of diagrams, photographs and microscopic time-lapse photography. Electron-microscope studies were also made. The normal loop was studied by means of labelling and removal experiments on the heart tube. The results demonstrated that the fusion of both cardiac primordia is made in stage 9 — in the mid-line of the embryo and that the first asymmetry of the heart tube appears in stage 10. The truncus region developed in situ directed towards the right after the fusion of both cardiac primordia, and in this region the electron-microscope study demonstrated a gradient of caudo-cephalic differentiation. In stage 10 the left caudal groove is the prospective interventricular groove, but the right caudal groove is not the right atrioventricular groove as had been stated by others. The asymmetric incorporation of both primordia begins in stage 11 —, when the curvature of the loop is already developing. In the removal experiments it was evident that the different portions of the cardiac tube in situ are orientated in space independently of the whole of the loop. The formation of the experimentally inverted loop is a mirror-image of the normal loop and appears to be originated through mechanic traction of the cardiac tube by the left splachnopleure and not by a faster displacement of the right cardiac primordia.

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Homing behaviour by destructive crown-of-thorns starfish is triggered by local availability of coral prey

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.1341 ◽

2020 ◽

Vol 287 (1938) ◽

pp. 20201341

Author(s):

S. D. Ling ◽

Z.-L. Cowan ◽

J. Boada ◽

E. B. Flukes ◽

M. S. Pratchett

Keyword(s):

Time Lapse ◽

Directional Movement ◽

The Pacific ◽

Population Outbreaks ◽

Population Outbreak ◽

And Diffusion ◽

Daily Displacement ◽

Logistic Modelling ◽

Time Lapse Photography

Corallivorous crown-of-thorns starfishes ( Acanthaster spp.) can decimate coral assemblages on Indo-Pacific coral reefs during population outbreaks. While initial drivers of population irruptions leading to outbreaks remain largely unknown, subsequent dispersal of outbreaks appears coincident with depletion of coral prey. Here, we used in situ time-lapse photography to characterize movement of the Pacific crown-of-thorns starfish ( Acanthaster cf. solaris ) in the northern and southern Great Barrier Reef in 2015, during the fourth recorded population outbreak of the starfish, but prior to widespread coral bleaching. Daily tracking of 58 individuals over a total of 1117 h revealed all starfish to move a minimum of 0.52 m, with around half of all tracked starfish showing negligible daily displacement (less than 1 m day −1 ), ranging up to a maximum of 19 m day −1 . Movement was primarily nocturnal and daily displacement varied spatially with variation in local availability of Acropora spp., which is the preferred coral prey. Two distinct behavioural modes emerged: (i) homing movement, whereby tracked paths (as tested against a random-walk-model) involved short displacement distances following distinct ‘outward' movement to Acropora prey (typically displaying ‘feeding scars') and ‘homebound' movement to nearby shelter; versus (ii) roaming movement, whereby individuals showed directional movement beyond initial tracking positions without return. Logistic modelling revealed more than half of all tracked starfish demonstrated homing when local abundance (percentage cover) of preferred Acropora coral prey was greater than 33%. Our results reveal facultative homing by Acanthaster with the prey-dependent behavioural switch to roaming forays providing a mechanism explaining localized aggregations and diffusion of these population irruptions as prey is locally depleted.

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