A low-cost and adjustable methodology for surveying marine species diversity within reef passages

Abstract

Reef passages are ecologically, socio-economically and culturally important habitats in Pacific Island Countries (PICs), yet remain poorly understudied and inadequately documented. We developed and deployed an adapted, low-cost, adjustable, suspended, baited remote underwater video (suspended-BRUV) system, specifically designed to monitor marine species diversity across three reef passages around Ovalau in Fiji, in the southwest Pacific. The suspended-BRUV deployment protocol and design were guided by local ecological knowledge and expertise from local fishers. A total of 36 deployments were conducted across three barrier reef passages, yielding 31 valid videos from which 1,001 individuals representing 60 species across 18 families were identified. Individuals cross-referenced with the IUCN Red List of Threatened Species revealed that two Critically Endangered, three Endangered, four Vulnerable and one Near-Threatened species were observed, demonstrating the effectiveness of this suspended-BRUV system in documenting conservation-relevant taxa. The system’s application demonstrated a strong potential as an effective tool for improving fisher-led biodiversity monitoring, even in highly dynamic environments such as reef passages, while also supporting community engagement, knowledge sharing and informing local management and conservation efforts. This study contributes to highlighting the importance of reef passages as biodiversity hotspots and encourages the need for inclusive, contextualized monitoring of coastal ecosystems.