Applying environmental DNA approaches to inform marine biodiversity conservation: The case of the Ocean Twilight Zone

Effective governance of the global ocean under accelerating environmental and social changes depends on sufficient scientific knowledge that unravels the complexity of dynamic marine ecosystems. In the case of the vast and remote ocean twilight zone (OTZ), management is particularly challenged by the lack of data. Traditional biodiversity monitoring methods are unable to scale efficiently or effectively to address these knowledge gaps and new technologies are needed to inform policy. Environmental DNA (eDNA) has quickly gained traction in recent years as an enabling technology for marine conservation that will play a transformative role in OTZ biodiversity conservation and high seas governance in general. Through a comprehensive review of science and policy literature and an analysis of existing global marine biodiversity data, we discuss the importance of biodiversity conservation in the OTZ, review existing knowledge gaps, and summarize recent developments in eDNA and OTZ biodiversity research. We identify the key components of an eDNA framework that are needed for OTZ biodiversity monitoring and discuss policy implications relevant to the recent Biodiversity Beyond National Jurisdiction (BBNJ) Agreement. We show that an integrated science-policy approach based on transdisciplinary eDNA research is essential for achieving sustainability in the OTZ and the 30x30 target for conserving ocean biodiversity.