Dataset: Snail larvae in turbulence and waves

Name: Processed data from Particle Imaging Velocimetry (PIV) observations of Tritia trivittata and Tritia obsoleta behavior in various flow tanks
Published: 2018-07-12
Keywords: acceleration, flow sensing, larval transport, wave climates, veligers, biota, oceans

Cite This Dataset

DOI:10.1575/1912/bco-dmo.739873

Spatial Extent: N:40.479535 E:-74.437189 S:40.479535 W:-74.437189

Temporal Extent: 2012-06-21 - 2014-07-10

Project:

Relative Influence of Turbulence and Waves on Larval Behavior (Turbulence and Larval Behavior)

Principal Investigator:

Heidi L. Fuchs (Rutgers University)

Co-Principal Investigator:

Adam J. Christman (Rutgers University)

Gregory P. Gerbi (Skidmore College)

Elias J. Hunter (Rutgers University)

Contact:

Heidi L. Fuchs (Rutgers University)

BCO-DMO Data Manager:

Shannon Rauch (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2018-07-12

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Processed data from Particle Imaging Velocimetry (PIV) observations of Tritia trivittata and Tritia obsoleta behavior in various flow tanks

Abstract:

Dispersing marine larvae can alter their physical transport by swimming vertically or sinking in response to environmental signals. However, it remains unknown whether any signals could enable larvae to navigate over large scales. We tested whether flow-induced larval behaviors vary with adults' physical environments using congeneric snail larvae from the wavy continental shelf (Tritia trivittata) and from turbulent inlets (Tritia obsoleta). This dataset includes observations of larvae in turbulence, in rotating flows dominated by vorticity or strain rates, and in rectilinear wave oscillations. Larval and water motion were observed using near-infrared particle image velocimetry (IR PIV), and analyses identified threshold signals causing larvae to change their direction or magnitude of propulsive force. The two species reacted similarly to turbulence but differently to waves, and their transport patterns would diverge in wavy, offshore regions. Wave-induced behaviors provide evidence that larvae may detect waves as both motions and sounds useful in navigation.

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Archival Copy

Version Date	Archive	Persistent Identifier (PID)	Date PID Issued
2018-07-12	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.1575/1912/bco-dmo.739873	2018-07-13

Description

These data are published in:
Fuchs, H.L., Gerbi, G.P, Hunter, E.J., & Christman, A.J. (2018, in press). Waves cue distinct behaviors and differentiate transport of congeneric snail larvae from sheltered versus wavy habitats. Proceedings of the National Academy of Sciences. doi: 10.1073/pnas.1804558115

The dataset includes processed data from Particle Imaging Velocimetry (PIV) observations of Tritia trivittata and Tritia obsoleta. For each experiment, replicates are pooled, and instantaneous observations from larval trajectories are condensed into tabular format. Data were collected from 21 June, 2012 to 10 July, 2014 at Rutgers' Department of Marine and Coastal Sciences.

Methods & Sampling

Larvae were observed in grid-stirred turbulence and in three devices producing simpler flows dominated by strain, vorticity, or acceleration. The three simpler flow devices were operated either vertically or horizontally. In each device, multiple forcing frequencies were used so that larvae experienced a broad range of physical signals with intensities representative of most ocean regions.

In each device, larvae were gently added along with 105 cells mL-1 algae (~18 μm preserved Thalassiosira weissflogii; Reed Mariculture) used as flow tracers. Movements of larvae and flow were measured simultaneously using 2-dimensional (2D), infrared particle-image velocimetry (PIV). The PIV system consisted of a 4 megapixel CCD camera (FlowSense, Dantec Dynamics) with a 100 mm lens (Tokina) and a pulsed diode laser (NanoPower 4W or 7W, 808 nm) with a ~2 mm beam width. Image sizes and locations varied among flow tanks (Fig. S1, Fuchs et al. 2018). After an initial 10-20 min acclimation period, larvae were observed in still water for 5 min, and then four or five flow treatments were applied in random order with ≥10 min of no oscillation between successive treatments. Each treatment included a 10 min spin-up period for the flow to become stationary (statistically invariant in time) followed by 5—20 min of recording.

Data Processing Description

Data were processed using DynamicStudio (v.4.10, Dantec) and Matlab (2011b through 2016b, Mathworks). Fluid and larvae move in different directions, so we first separated the PIV images of particles and larvae using techniques for 2-phase flow. Fluid velocities were computed from the particle images with larvae masked out, and larval translational velocities were calculated from larval trajectories. Fluid motion and larval translation differ due to swimming or sinking movement relative to flow outside the larval boundary layer. In the vertical (z) dimension, wb=wo-wf, where wb is the instantaneous behavioral velocity, wf is the instantaneous flow velocity, and wo is the instantaneous translational (observed) velocity of an individual larva. The horizontal behavioral velocities were computed similarly for ub in the x dimension. Trajectories had mean durations of ~2 s in the weakest flow conditions down to ~0.1 s in the strongest flow conditions and were too short to analyze behavioral changes over time.

We used the PIV data to analyze larval swimming mechanics as a response to the instantaneous flow environments around individual larvae (Fuchs et al. 2013, 2015a, 2015b). The relevant hydrodynamic signals are the dissipation rate ε, strain rate γ, horizontal component of vorticity ξ, and fluid acceleration α. We calculated 2D approximations of these signals from fluid velocities and their gradients, interpolated in space and time to the larval observations.

Approximations for ε varied among flow tanks (Fuchs et al. 2013, 2015b). We also calculated the instantaneous fluid forces on individual larvae. The product of larval mass and acceleration is balanced by a vector sum of forces, including gravity, buoyancy, drag, Basset history forces, fluid acceleration, and the force that larvae exert to propel themselves (see Appendix of Fuchs et al. 2015b). Assuming larvae to be spherical, we computed all terms except propulsive force from measured velocities, larval size, and density (Fuchs et al. 2013), then solved the force balance equation for the propulsive force vector Fv, which indicates the magnitude and Cartesian direction of larval swimming effort. The propulsion direction was corrected to larval coordinates by estimating the vorticity-induced larval tilt angle ϕ (Fuchs 2013), and larvae were classified as "swimming" or "sinking/diving" if their propulsive force was directed upward (velum direction) or downward (shell direction), respectively, relative to the body axis.

Data Files

File
PIV_snail_larvae.csv (Comma Separated Values (.csv), 61.56 MB) MD5:b17b9ea3986996aebc3575d5ed7fa54f Primary data file for dataset ID 739790

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1060622

Deployments

None available yet

Instruments

Particle Image Velocimetry (PIV) system

Supplied Name: near-infrared (IR) particle image velocimeter (IR PIV)

Supplied Description:

Larval behavior and flow were observed simultaneously using near-infrared (IR) particle image velocimeter (IR PIV). The PIV system consisted of a 4 megapixel CCD camera (FlowSense, Dantec Dynamics) with a 100 mm lens (Tokina) and a pulsed diode laser (NanoPower 4W or 7W, 808 nm) with a ~2 mm beam width.

Instrument Type

Generic Name: Particle Image Velocimetry (PIV) system

Generic Description:

Measures 2D velocity flow fields, usually by scanning particles with a laser beam and capturing images of the illuminated particles.

Parameters

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
x	x	centimeters (cm)	no_bcodmo_term
z	y	centimeters (cm)	no_bcodmo_term
uf	uf	centimeters per second (cm/s)	no_bcodmo_term
wf	wf	centimeters per second (cm/s)	no_bcodmo_term
ub	ub	centimeters per second (cm/s)	no_bcodmo_term
wb	wb	centimeters per second (cm/s)	no_bcodmo_term
acceleration	acceleration at larval location	meters per second (m s^-2)	no_bcodmo_term
dissipation_rate	Dissipation rate at larval location	m^2 s^-3	no_bcodmo_term
larval_propulsive_force	Larval propulsive force magnitude	N	no_bcodmo_term
larval_axial_rotation_ang	Larval axial rotation angle	radians	no_bcodmo_term
propulsion_direction	Propulsion direction relative to larval axis	radians	no_bcodmo_term
horizontal_comp_of_vorticity	horizontal component of vorticity at larval location	s^-1	no_bcodmo_term
strain_rate	strain rate at larval location	s^-1	no_bcodmo_term
file_name	Original name of csv file	unitless	file_name
larval_stage	Larval stage: Precomp = precompetent larvae; Comp = competent larvae	unitless	stage
species	Name of species: T_trivittata = Tritia trivittata; T_obsoleta = Tritia obsoleta	unitless	species
flow_tank	Type of flow tank: turb = grid-stirred turbulence tank; couette = Couette device; rotate = rotating cylinder; accel = shaker flask	unitless	tank
direction	Direction (axis of rotation for Couette device and rotating cylinder, direction of oscillation for shaker flask): H = horizontal; V: vertical	unitless	no_bcodmo_term