Otter Health Index (OHI): Methodological Toolkit

Methodological toolkit for the Otter Health Index (OHI), a low-cost bioindicator system that assesses ecological integrity of tropical estuaries using the Neotropical otter (Lontra longicaudis) as a sentinel species. This package comprises three integrated resources: (1) an explanatory video detailing the OHI framework and field application; (2) a standardized input template ("Input data for Otter Health Index.csv") for recording four core metrics scored 0–10—Spraint Frequency (relative abundance), Toxic Load (contaminants in spraints), Habitat Connectivity (ecological corridors), and Community Perception; and (3) a scoring guide ("Scoring Guide for Otter Health Index.csv") providing objective criteria across three interpretive bands: Green (10–8 points: healthy conditions), Yellow (7–5: early warning), and Red (4–0: critical degradation). The toolkit enables technicians, NGOs, municipal environmental agencies, and traditional communities to monitor estuary health without specialized laboratories, generating a composite OHI score (0–40) with color-coded interpretation for rapid decision-making. Designed for accessibility in data-scarce contexts, the OHI supports conservation planning, environmental education, and evidence-based policy across Brazil's threatened coastal ecosystems. This open-access resource forms part of Projeto Lontra's four-decade legacy (since the 1980s) of long-term otter monitoring and socio-ecological research in the Atlantic Forest and Pantanal biomes. All materials are published under CC-BY 4.0 to foster collaborative science and empower local stewardship of estuarine biodiversity. Recommended citation format for derived research: "Data collected using the Otter Health Index (OHI) methodology; see Carvalho Júnior et al., Zenodo DOI:10.5281/zenodo.XXXXXXXX."