The study examines the effectiveness of marine protected areas (MPAs) in conserving marine biodiversity, focusing on the five key features that enhance their conservation outcomes: no-take zones, well-enforced regulations, old age (>10 years), large size (>100 km²), and isolation by deep water or sand. The research, conducted by a team of scientists from the University of Tasmania and other institutions, analyzed data from 87 MPAs worldwide. Key findings include: 1. **Conservation Benefits**: MPAs with all five key features showed significantly higher fish biomass and species richness compared to fished areas. Effective MPAs had twice as many large fish species and five times more large fish biomass, and 14 times more shark biomass. 2. **Socio-Economic and Biological Factors**: Various socio-economic and biological factors influence the effectiveness of MPAs, including human population density, phosphate concentration, and environmental conditions. 3. **Isolation**: Isolation by deep water or sand was particularly influential, with MPAs that were isolated showing significantly higher biomass and species richness. 4. **MPA Design and Management**: The study emphasizes the need for better MPA design, durable management, and compliance to ensure that MPAs achieve their desired conservation value. Only 10% of the MPAs studied had all five key features, indicating that many are not ecologically effective. 5. **Global Impact**: The study provides a global assessment of the magnitude of fishing impacts on reef communities, showing that fishing has reduced fish biomass by about two-thirds from historical baselines. 6. **Future Conservation**: The authors argue that expanding the network of effective MPAs and improving fisheries management practices are crucial for safeguarding marine biodiversity and preventing further extinctions of large-bodied species. The research highlights the importance of comprehensive and well-managed MPAs in achieving effective marine conservation.The study examines the effectiveness of marine protected areas (MPAs) in conserving marine biodiversity, focusing on the five key features that enhance their conservation outcomes: no-take zones, well-enforced regulations, old age (>10 years), large size (>100 km²), and isolation by deep water or sand. The research, conducted by a team of scientists from the University of Tasmania and other institutions, analyzed data from 87 MPAs worldwide. Key findings include: 1. **Conservation Benefits**: MPAs with all five key features showed significantly higher fish biomass and species richness compared to fished areas. Effective MPAs had twice as many large fish species and five times more large fish biomass, and 14 times more shark biomass. 2. **Socio-Economic and Biological Factors**: Various socio-economic and biological factors influence the effectiveness of MPAs, including human population density, phosphate concentration, and environmental conditions. 3. **Isolation**: Isolation by deep water or sand was particularly influential, with MPAs that were isolated showing significantly higher biomass and species richness. 4. **MPA Design and Management**: The study emphasizes the need for better MPA design, durable management, and compliance to ensure that MPAs achieve their desired conservation value. Only 10% of the MPAs studied had all five key features, indicating that many are not ecologically effective. 5. **Global Impact**: The study provides a global assessment of the magnitude of fishing impacts on reef communities, showing that fishing has reduced fish biomass by about two-thirds from historical baselines. 6. **Future Conservation**: The authors argue that expanding the network of effective MPAs and improving fisheries management practices are crucial for safeguarding marine biodiversity and preventing further extinctions of large-bodied species. The research highlights the importance of comprehensive and well-managed MPAs in achieving effective marine conservation.