List of Materials for Fieldwork¶
Camera Monitoring Unit
Trail camera (fully charged, batteries installed, formatted SD card)
GPS
Camera (phone camera is sufficient)
Sampling quadrat (50cm x 50cm) with markings every 10 centimetres on each side.
Fieldwork Datasheet and pen / pencil
Deployment Procedures¶
Verify that the camera is fully charged and the SD card is formatted.
Locate your sampling location in one of the two microhabitats. Take a GPS waypoint and record the waypoint number.
Place down the camera monitoring unit and start the timelapse recording.
If deploying with the quadrat, place down the quadrat below the camera monitoring unit so that it is visible. Leave the quadrat for 5 minutes.
While waiting for the 5 minutes, fill out the fieldwork datasheet. If deploying underneath the canopy, take a photo of the canopy directly above the camera monitoring unit.
After 5 minutes, retrieve the quadrat and exit the site, leaving only the camera monitoring unit.
Important Deployment Notes¶
Ensure that the camera settings are correct prior to deployment (see section on recommended trail camera settings).
Deploy in an area that has signs of crab activity such as burrows, bioturbation, etc.
Do not place the monitoring unit above thick vegetation, overgrown areas, or thick roots.
Ensure that the monitoring unit is placed on a flat and level surface in one of the two microhabitats.
The camera must NOT be submerged at any point during the high tide.
Ensure that the spot you have selected has sufficient lighting for the camera. For trail cameras, you can check this by using the live image. This will appear in black & white if lighting is insufficient - in this case, avoid that spot.
Obtain an equal number of deployments (samples) for each of the two microhabitats (canopy gap AND underneath the tree canopy).
Minimum Requirements for Cameras¶
General Requirements:
Accepts an SD card of 128GB or larger
Weatherproof (even better if it is waterproof)
Produces high resolution photos of crabs that can be used as species ID (when deployed at a height of 50cm above the ground)
Samples an area of at least 20cm x 20cm, but no larger than 100cm x 100cm when facing directly down at a height of 50cm. The sweet spot is that it samples an area of 50cm x 50cm (size of quadrat)
Timelapse Capabilities:
Minimum photo quality of 8 megapixels (approximately a resolution of 3840 x 2160 pixels); higher resolutions are even better.
Capable of taking photos at intervals ranging from every 5 seconds to 5 minutes. We suggest setting the timelapse interval to take a photo every 2 minutes.
Video Capabilities*:
Minimum resolution of 1920 x 1060 pixels.
'* Videos can be used when deployments will last around 1 hour at a time. However, this means that repeat visits and video samples are necessary to achieve monitoring objectives.
Recommended Trail Camera Settings¶
Exact options may vary per camera model. Please try to set your camera to settings as close as possible to these ones.
Capture Mode: Photo
Trigger Mode: Time Lapse
Timelapse Interval: 00:02:00 (1 photo every 2 minutes)
Loop Recording: Off
Fill Light Intensity: Auto
Monitoring Period: Off
Grid Frequency: 60 Hz
Image Size: 73M
Picture No: 1 Photo
Shutter Speed: 1/30
Ensure that you set the date and time correctly (time format: 24H)
Camera Monitoring Unit Requirements¶
To ensure consistency in monitoring, we have specifications for each camera monitoring unit that our trail cameras are mounted to. These are outlined below:
Camera is at least 50cm above the ground
A variety of materials can be used, as long as the monitoring structure is stable and strong enough to be left in the field for up to 3 months.
The camera must be facing directly downwards.
The field of view seen by the camera 20cm x 20cm and 100cm x 100cm. It does not have to be a perfect square, as long as you know the exact area.
A quadrat with markings every 10 centimetres on each side should be placed down in front of the camera for two timelapse cycles (i.e if the camera takes photos every 2 minutes, the quadrat should be left for at least 4 minutes). After this time, the quadrat can be removed. This is to aid in crab sizing and density estimates.
Further information can be found in the “Camera Monitoring Unit Specifications” section in the previous chapter.