MARS: Programmable multipurpose auto-release system for aquatic observations

Abstract

Aquatic biodiversity assessments are often labor-intensive due to the large size of the equipment and the complex logistics of sea vessel operations. Traditional drift and drop cameras are typically tethered to the surface, causing cable and line clutter on sea vessels. At the same time, landers rely on auto-release mechanisms that use costly acoustic signals or inaccurate galvanic reactions. We introduce a reusable, novel, and low-cost Multipurpose Auto-Release System, a versatile and programmable solution for diverse payloads and applications in shallow and mesophotic waters. Building on existing drop-cam and Baited Remote Underwater Video System techniques, we enhance them with natural ballasts and an electronically controlled timed-release mechanism, which is programmed via a smartphone app using Near Field Communication. Our technique allows tetherless retrieval from small sea vessels at the sea surface. This innovation simplifies aquatic monitoring logistics by eliminating the need for surface buoys or equipment retrieval from the seabed during each deployment. Our approach also advances benthic and deep-sea marine biodiversity assessments by enabling easy systems deployment and recapture without pingers. We validated the system through 10 seawater tests, reaching depths of 278 m, accumulating 6 h of submerged data collection, and 17 d during continuous water immersion. We provide a detailed guide for building this robust, reusable, user-friendly tool for diverse aquatic monitoring assessments. Additionally, we share key lessons learned, paving the way toward more democratized, customizable, and widely accessible applications capable of reaching the deepest seas.