Underwater stand-alone observatory landers as a tool for deep-sea habitat restoration monitoring

We present the development and application of an underwater stand-alone observatory lander designed specifically to moni- tor the restoration of deep-sea habitats. This low-cost, modular system combines robust usability with advanced monitoring ca- pabilities. Continuous monitoring of restoration sites enables time-lapse observation of benthic ecosystems, providing valuable insights into the recovery of seafloor habitats and fostering an understanding of ecological transitions. Initial deployments of the lander have demonstrated its utility in capturing high-resolution imagery and environmental data at restoration sites, supporting the acquisition of baseline data critical for assessing restoration efficacy. In December 2024, a coordinated deployment of three underwater observatory landers was conducted to monitor the effectiveness of passive deep-sea habitat restoration techniques in the north-western Mediterranean Sea. Strategically positioned across restoration sites, the landers can provide comprehensive spatial and temporal coverage, capturing high-resolution time- lapse imagery and environmental data of the seabed. These ob- servations focus on documenting ecological transitions within the restored habitats, enabling the identification of key indicators of recovery such as species colonization, sediment dynamics, and habitat provision.