Invasive Tunicate Occurrence and Cover in Bay of Fundy Drift Transects

386 high-resolution still images and segmented video transects document the occurrence and percent cover of the invasive colonial tunicate Didemnum vexillum in the western Bay of Fundy. The survey found D. vexillum in 44% of the sampled area at depths from 34 to 118 meters, deeper than previous global reports. Data was collected via drift-camera transects in the Head Harbour/West Isles Archipelago Ecologically and Biologically Significant Area.

Use Cases

• Train computer vision models to detect D. vexillum colonies in high-resolution still images and video segments.
• Analyze the relationship between D. vexillum percent cover categories (>50%, 26-50%, 6-25%, ≤5%) and transect depth or location.
• Model the invasive species' distribution using frequency of occurrence classifications (common, occasional, rare) from video segments.
• Estimate the total area sampled by multiplying the standardized field of view (FOV) by the distance travelled in each video segment.

Strengths

• Dataset includes 386 high-resolution still images with categorized percent cover estimates.
• Documents D. vexillum presence in 44% of the sampled area, providing a clear invasion metric.
• Records observations at depths from 34 to 118m, extending known depth range for this species.

Limitations

• Sample size is limited to seven drift-camera transects within a single ~113 km2 area.
• Video segments deemed unusable due to turbidity or camera height were removed, potentially biasing coverage estimates.
• Percent cover and frequency classifications are categorical estimates, not continuous measurements.

Provenance

Source

Fisheries and Oceans Canada.

Collection Method

Optical imagery benthic survey using drift-camera transects, with data derived from high-resolution still images and segmented HD video.

Freshness

Data last updated in March 2026.

Geography

Head Harbour/West Isles Archipelago/The Passages Ecologically and Biologically Significant Area in the western Bay of Fundy, New Brunswick, Canada.