Animal Movement Modeling

dBSea supports modeling marine animal movement and sound exposure. This feature is useful for environmental impact assessments where understanding how animals may respond to underwater noise is important, and where given TTS or PTS thresholds must be met.

Overview

dBSea provides two approaches to animal movement modeling:

• Simple fleeing model - A straightforward model where animals move directly away from sound sources when levels exceed a threshold
• 3MB integration - Integration with the 3MB (Marine Mammal Movement and Behavior) model for more complex behavioral simulation

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Simple Fleeing Model

The simple fleeing model provides a quick way to estimate animal displacement without configuring complex behavioral parameters.

How It Works

1. Animals are placed at specified starting locations
2. At each time step, the sound level at each animal’s position is calculated
3. If the level exceeds the fleeing threshold, the animal moves directly away from the loudest source
4. Movement continues until levels drop below the threshold or the simulation ends

Setup

To configure a simple fleeing simulation:

1. Go to the Animal Movement settings
2. Select Simple fleeing model
3. Configure the parameters:
   • Fleeing threshold (dB) - Sound level that triggers fleeing behavior
   • Swimming speed (m/s) - Speed at which animals move when fleeing
   • Starting positions - Initial locations of animals (can be imported from CSV)
   • Simulation duration - Total time to simulate
4. Click Run to start the simulation

Output

The simple fleeing model produces:

• Movement tracks showing animal positions over time
• Final displacement distances from starting positions
• Cumulative sound exposure (SEL) for each animal
• Maximum SPL experienced

The simple fleeing model tends to produce conservative (higher) displacement estimates since it assumes animals flee directly away from sources.

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3MB Integration

For more sophisticated behavioral modeling, dBSea integrates with 3MB (Marine Mammal Movement and Behavior), an external model framework developed for marine mammal exposure assessment.

How the Integration Works

dBSea provides the acoustic environment to 3MB:

1. Configure and solve your acoustic model in dBSea
2. Export the sound field data for use by 3MB
3. 3MB runs its behavioral simulation using the exported acoustic data
4. Import 3MB results back into dBSea for visualization and analysis

What dBSea Provides to 3MB

• Calculated sound levels across the model domain
• Time-varying fields for moving source scenarios
• Frequency-weighted levels (e.g., M-weighting for marine mammals)

Viewing 3MB Results in dBSea

After running a 3MB simulation, import the results into dBSea to:

• Overlay animal tracks on the acoustic model
• Visualize exposure levels along movement paths
• Export combined results for reporting

For detailed information on configuring and running 3MB simulations, refer to the 3MB documentation: https://oalib.hlsresearch.com/Sound%20and%20Marine%20Mammals/3MB%20HTML.htm

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Choosing a Model

Use Case	Recommended Model
Quick screening assessment	Simple fleeing
Conservative displacement estimates	Simple fleeing
Detailed behavioral analysis	3MB
Regulatory submissions requiring behavioral modeling	3MB

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Probe to Source Back-Calculation

The probe to source back-calculation function is useful for animal exposure work:

1. Place a probe at a location of interest
2. Specify a target received level (e.g., a regulatory threshold)
3. Calculate the source level required to produce that level at the probe

This helps determine source levels that would result in specific exposure levels at animal locations.