Cresswell AKRyan NMHeyward AJSmith ANHColquhoun JCase MBirt MJChinkin MWyatt MRadford BCostello PGilmour JPToonen R2024-01-042024-07-252021-04-142024-01-042024-07-252021Cresswell AK, Ryan NM, Heyward AJ, Smith ANH, Colquhoun J, Case M, Birt MJ, Chinkin M, Wyatt M, Radford B, Costello P, Gilmour JP. (2021). A quantitative comparison of towed-camera and diver-camera transects for monitoring coral reefs.. PeerJ. 9. (pp. e11090-).2167-8359https://mro.massey.ac.nz/handle/10179/70861Novel tools and methods for monitoring marine environments can improve efficiency but must not compromise long-term data records. Quantitative comparisons between new and existing methods are therefore required to assess their compatibility for monitoring. Monitoring of shallow water coral reefs is typically conducted using diver-based collection of benthic images along transects. Diverless systems for obtaining underwater images (e.g. towed-cameras, remotely operated vehicles, autonomous underwater vehicles) are increasingly used for mapping coral reefs. Of these imaging platforms, towed-cameras offer a practical, low cost and efficient method for surveys but their utility for repeated measures in monitoring studies has not been tested. We quantitatively compare a towed-camera approach to repeated surveys of shallow water coral reef benthic assemblages on fixed transects, relative to benchmark data from diver photo-transects. Differences in the percent cover detected by the two methods was partly explained by differences in the morphology of benthic groups. The reef habitat and physical descriptors of the site-slope, depth and structural complexity-also influenced the comparability of data, with differences between the tow-camera and the diver data increasing with structural complexity and slope. Differences between the methods decreased when a greater number of images were collected per tow-camera transect. We attribute lower image quality (variable perspective, exposure and focal distance) and lower spatial accuracy and precision of the towed-camera transects as the key reasons for differences in the data from the two methods and suggest changes to the sampling design to improve the application of tow-cameras to monitoring.(c) 2021 The Author/sCC BY 4.0https://www.creativecommons.org/licenses/by/4.0/BenthicCoral reef monitoringImage analysisMappingMethodologyMethods comparisonTechnologyTowed videoJournal article10.7717/peerj.110902167-8359journal-articlee11090-https://www.ncbi.nlm.nih.gov/pubmed/33954031ARTN e1109011090