High-Resolution Drone Images Show That the Distribution of Mussels Depends on Microhabitat Features of Intertidal Rocky Shores

In this study, we used orthomosaics and a digital surface model (DSM) generated from drone surveys to (1) characterize the distribution of mussel (Mytilus galloprovincialis) aggregations at high resolution (centimeters), (2) evaluate role topographic features, intertidal height, slope, orientation angle in determining on two rocky shores oriented differently both sides beach French Brittany coast. We first developed tested visualization index (MVI) for mapping images. Then, analyzed shores. The results showed contrasted total mussel-occupied area between shores, with higher occupation rate clear pattern depending features shore west. Intertidal its associated immersion time, was main factor distribution. An optimum height found center range, c.a. 4.5 m above lowest astronomical tide (LAT), where individuals are under phase average 43% time. Within optimum, mussels significantly microhabitats facing south west, particularly intermediate slope angles. These demonstrate microhabitat development their final Furthermore, highlight importance mesoscale structures habitats (e.g., 100 m), which seem be responsible differences observed Our methodological approach highlights advantage using high-resolution images address ecological processes ecosystems. Indeed, imagery offers possibility assess small-scale interactions habitat conditions over wide area, is technically infeasible fieldwork approaches or by satellite remote sensing due lower resolution. Scale integration complementarity powerful correctly represent governing ecology suggest methodology monitor long-term changes sentinel sessile species.