Using unoccupied aerial vehicles to map and monitor changes in emergent kelp canopy after an ecological regime shift

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Date
2022-09-21
Authors
Saccomanno, Vienna R.
Bell, Tom W.
Pawlak, Camille
Stanley, Charlotte K.
Cavanaugh, Katherine C.
Hohman, Rietta
Klausmeyer, Kirk R.
Cavanaugh, Kyle
Nickels, Abby
Hewerdine, Waz
Garza, Corey
Fleener, Gary
Gleason, Mary
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DOI
10.1002/rse2.295
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Keywords
Conservation monitoring
Emergent kelp
Remote sensing
Unoccupied aerial vehicles
Abstract
Kelp forests are complex underwater habitats that form the foundation of many nearshore marine environments and provide valuable services for coastal communities. Despite their ecological and economic importance, increasingly severe stressors have resulted in declines in kelp abundance in many regions over the past few decades, including the North Coast of California, USA. Given the significant and sustained loss of kelp in this region, management intervention is likely a necessary tool to reset the ecosystem and geospatial data on kelp dynamics are needed to strategically implement restoration projects. Because canopy‐forming kelp forests are distinguishable in aerial imagery, remote sensing is an important tool for documenting changes in canopy area and abundance to meet these data needs. We used small unoccupied aerial vehicles (UAVs) to survey emergent kelp canopy in priority sites along the North Coast in 2019 and 2020 to fill a key data gap for kelp restoration practitioners working at local scales. With over 4,300 hectares surveyed between 2019 and 2020, these surveys represent the two largest marine resource‐focused UAV surveys conducted in California to our knowledge. We present remote sensing methods using UAVs and a repeatable workflow for conducting consistent surveys, creating orthomosaics, georeferencing data, classifying emergent kelp and creating kelp canopy maps that can be used to assess trends in kelp canopy dynamics over space and time. We illustrate the impacts of spatial resolution on emergent kelp canopy classification between different sensors to help practitioners decide which data stream to select when asking restoration and management questions at varying spatial scales. Our results suggest that high spatial resolution data of emergent kelp canopy from UAVs have the potential to advance strategic kelp restoration and adaptive management.Despite their ecological and economic importance, kelp forest abundance has declined in many regions around the world including the North Coast of California. Given the significant loss of kelp in this region, management intervention is likely necessary and remotely sensed data on kelp dynamics can help inform strategic restoration projects. We used unoccupied aerial vehicles (UAVs) to survey emergent kelp canopy along the North Coast in 2019 and 2020 and present remote‐sensing based kelp survey methods using UAVs. Our results suggest that high spatial resolution data on local‐scale spatiotemporal patterns of emergent kelp canopy from UAVs have the potential to advance strategic kelp restoration and adaptive management.
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© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Saccomanno, V. R., Bell, T., Pawlak, C., Stanley, C. K., Cavanaugh, K. C., Hohman, R., Klausmeyer, K. R., Cavanaugh, K., Nickels, A., Hewerdine, W., Garza, C., Fleener, G., & Gleason, M. Using unoccupied aerial vehicles to map and monitor changes in emergent kelp canopy after an ecological regime shift. Remote Sensing in Ecology and Conservation, 9(1), (2022): 62-75, https://doi.org/10.1002/rse2.295.
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Saccomanno, V. R., Bell, T., Pawlak, C., Stanley, C. K., Cavanaugh, K. C., Hohman, R., Klausmeyer, K. R., Cavanaugh, K., Nickels, A., Hewerdine, W., Garza, C., Fleener, G., & Gleason, M. (2022). Using unoccupied aerial vehicles to map and monitor changes in emergent kelp canopy after an ecological regime shift. Remote Sensing in Ecology and Conservation, 9(1), 62-75.
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