Autonomous seeking and mapping coral reef biodiversity hotspots with a multimodal AUV

Coral reefs are under threat worldwide. Yet, in these often-challenging marine habitats, biologists lack the tools to quantify the spatial heterogeneity of mobile reef fauna at high resolution (<1 meter), hampering monitoring and restoration efforts. Because of the diverse species present, multiple sensor modalities are needed to characterize the biodiversity. The urgent need to expand this study across unexplored reefs worldwide compounds these challenges. To address these problems, we propose a generative model of reef observations and develop a multimodal framework for seeking and mapping hotspots of biodiversity. In a case study on a healthy Caribbean reef, our autonomous underwater vehicle used passive acoustics and visual sensing to locate a biological hotspot around a large Dendrogyra pillar coral. We used the colocated multimodal data to self-validate the hotspot's prominence, representing a technological step forward to help understand the ecological dynamics of coral reefs.