Incorporating Structure-from-Motion (SfM) Photogrammetry into Sedimentation Monitoring

This project assessed the use of Structure-from-Motion (SfM) photogrammetry and large-area imagery (LAIs) to enhance sedimentation monitoring and coral reef habitat evaluations near Port Everglades (PEV) and Port of Miami (POM). By utilizing high-resolution LAIs and 3D models, we quantified sediment cover, benthic composition, colony-level responses, and structural complexity across reef habitats.
 

Sediment-associated habitats were prevalent in many surveyed areas, showing spatial variability among reef types. The Middle reef at PEV had significantly higher sand cover and lower sponge cover than other habitats, while hard coral cover remained low across all sites. These findings suggest that sediment exposure varies and may be concentrated in specific geomorphic settings, warranting consideration in future assessments. Although temporal changes over the sampling interval were limited, there was a notable increase in sand cover at POM in the second survey, indicating that LAIs sensitivity to detect small sediment changes.
 

Agreement between field and digital observations of sponge sediment-stress indicators was 73.2%, reinforcing the reliability of LAIs. Coral responses varied, with reduced growth probability and greater shrinkage observed in some PEV habitats, whereas POM colonies exhibited more stable patterns. These results should be interpreted with caution, given the short duration, but they highlight the potential of LAIs to reveal subtle changes at the colony level. Also, digital 3D rugosity metrics captured finer structural variation than field chain-and-tape methods, indicating that photogrammetric approaches are particularly valuable for monitoring subtle habitat complexity changes associated with sedimentation
 

SfM and LAIs present a reproducible and scalable framework that can enhance monitoring by: 1) identifying sediment “hotspots”; 2) supporting baseline and post-project monitoring; 3) providing permanent records for longitudinal analysis; and 4) integrating various metrics into a unified assessment platform. Combining these tools with existing diver-based and water-quality monitoring can improve detection of changes and inform habitat-specific management decisions for sediment-stressed reefs near ports.