Very high resolution mapping of coral reef state using airborne bathymetric LiDAR surface-intensity and drone imagery

Abstract

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Underwater photogrammetry reveals new links between coral reefscape traits and fishes that ensure key functions

“…Emerging technologies such as LIDAR and airborne imagery (Asner et al, 2020; Collin et al, 2018; Wedding et al, 2019), three‐dimensional (3D) scanning (Reichert et al, 2016), or photogrammetry (Burns et al, 2015; Lange & Perry, 2020) can help fill these gaps. For example, they allow the computation of ecological and physical descriptors of benthic assemblages at multiple spatial scales, including descriptors not easily assessed through visual surveys.…”

Spatial covariation in nutrient enrichment and fishing of herbivores in an oceanic coral reef ecosystem

“…We mapped the inner edge of the reef crest, the shore line and openings to each of the 11 passes on Moorea based on LiDAR‐based digital elevation maps produced from an airborne LiDAR campaign conducted in 2015 (Collin et al, 2018 ). Furthermore, we created a spatial habitat layer that classified areas of the lagoon 3 m or shallower into three habitats: fringing reef, mid‐lagoon, and back reef.…”

“…The relative distance to shore was calculated as the distance to the nearest point on the shore as a fraction of the total distance from the shore to the reef crest passing through that point, such that locations on the shore have a value of 0 and locations at the reef crest have a value of 1. Finally, depth for any location within lagoons was assigned based on LiDAR data (Collin et al, 2018 ), averaged within each 25 × 25 m grid cell.…”

Drones address an observational blind spot for biological oceanography

“…Drones can be equipped with a range of sensors – often passive remote sensing using optical and thermal wavelengths, but occasionally active remote‐sensing systems (such as LiDAR) for water column profiling and bathymetric mapping (Collin et al . 2018). Although limited, samplers for marine aerosols, water quality, and passive acoustic monitoring have also been deployed (Corrigan et al .…”

“…Drones can be rapidly deployed and recovered by hand from both large ships and small boats in response to dynamic features without substantial delay to other ship operations (Figure 4), and can be quickly integrated into a diverse set of sampling regimes across polar, temperate, and tropical marine environments (Johnston 2019). Drones can be equipped with a range of sensors -often passive remote sensing using optical and thermal wavelengths, but occasionally active remote-sensing systems (such as LiDAR) for water column profiling and bathymetric mapping (Collin et al 2018). Although limited, samplers for marine aerosols, water quality, and passive acoustic monitoring have also been deployed (Corrigan et al 2008;Lloyd et al 2017;Terada et al 2018).…”