Potential for synergistic conservation through area-based strategies.

The ongoing biodiversity crisis has raised concerns about the effectiveness of area-based conservation (ABC) strategies for achieving positive biodiversity outcomes. In riverine ecosystems, the linear habitat structure of fishes introduces uncertainty into the synergistic conservation potential of ABC. Therefore, to assess the synergistic conservation potential of ABC for multiple groups, we used data from IUCN and RivFishTIME database up to 2020 for fishes, mammals, and birds to assess the reliability of area sampling based on species-area relationships and latitudinal dependence analyses. We built a spatial model of species richness to determine the spatial distribution of species richness and the spatial overlap of species richness within and among the 3 groups under different group combinations. We found a significant power function relationship between area and species richness; R² values ranged from 0.94 to 0.96. Species richness was unevenly distributed across groups; thus, the potential for synergistic conservation of multiple groups is not promising. Fish were outliers. The spatial overlap for fish-bird combinations (β = -0.001 to 0.02) and fish-mammal combinations (β = 0.10-0.11) were significantly lower than those for mammal-bird combinations (β = 0.20-0.27). This calls for targeted conservation planning for fishes in terrestrial ecosystems rather than considering that protected areas for mammals and birds will also protect fishes. Furthermore, the synergistic conservation potential of multitarget strategies cannot be safely extended to all groups.