Applications of unmanned aerial vehicles in intertidal reef monitoring

Abstract

Monitoring of intertidal reefs is traditionally undertaken by on-ground survey methods which have assisted in understanding these complex habitats; however, often only a small spatial footprint of the reef is observed. Recent developments in unmanned aerial vehicles (UAVs) provide new opportunities for monitoring broad scale coastal ecosystems through the ability to capture centimetre resolution imagery and topographic data not possible with conventional approaches. This study compares UAV remote sensing of intertidal reefs to traditional on-ground monitoring surveys, and investigates the role of UAV derived geomorphological variables in explaining observed intertidal algal and invertebrate assemblages. A multirotor UAV was used to capture <1 cm resolution data from intertidal reefs, with on-ground quadrat surveys of intertidal biotic data for comparison. UAV surveys provided reliable estimates of dominant canopy-forming algae, however, understorey species were obscured and often underestimated. UAV derived geomorphic variables showed elevation and distance to seaward reef edge explained 19.7% and 15.9% of the variation in algal and invertebrate assemblage structure respectively. The findings of this study demonstrate benefits of low-cost UAVs for intertidal monitoring through rapid data collection, full coverage census, identification of dominant canopy habitat and generation of geomorphic derivatives for explaining biological variation.

Cicada (&lt;i&gt;Magicicada&lt;/i&gt;) Tree Damage Detection Based on UAV Spectral and 3D Data

“…This may include not only vegetated features but any structure in which the goal is to better classify its extent or compare a location to its neighbors such as in stream riparian corridor analysis for the purpose of additional derivatives such as flow direction, accumulation, heat load index, topographic moisture index, and other geomorphic attributes [22,[48][49][50]. Compared to earlier remote sensing platforms in which only satellite or fixed wing aircraft provide spectral information, the inclusion of the structure from motion output from UAVs makes it a unique and very promising alternative to the traditional aerial imagery sources.…”

“…The main advantages of the UAV are the low cost of acquisition [19,20], possibility of frequent monitoring [21,22], adaptability to carry various sensors, as thermal, infrared and multispectral cameras or even Lidar scanners [19,[23][24][25], the high resolution obtained [19,23,26], and the development of processing software focused on the automatic reconstruction of surfaces using the UAV data [27,28]. An example of surface reconstruction has been in forest structure [29].…”

Future sea-level rise drives rocky intertidal habitat loss and benthic community change

“…Recent advances in remote sensing, digital imaging, and modern computing now provide researchers new opportunities to explore the interplay between spatial patterns and ecological processes in the rocky intertidal at spatial scales never before possible (from the millimeter to the kilometer scale) [40][41][42].…”

“…orthophotos) of the intertidal (Fig 2). The details of 3D model and orthophoto creation have been described in detail elsewhere [40][41][42]48].…”

“…Similar approaches are needed more broadly for global coastlines in order to understand how to manage and mitigate impending global change impacts [42].…”