Wetland protection enhances the taxonomic and functional diversity of aquatic insects and modifies community assembly processes

Protected areas are considered an effective approach for conserving biodiversity. However, our understanding of their effects on aquatic organisms in wetlands remains limited, particularly for invertebrates. This study aims to address this gap by evaluating the effects of protected areas on aquatic insect biodiversity at local and regional scales. Our results revealed significant differences in aquatic insect assemblages between protected and impaired wetlands. Protected wetlands exhibited significantly higher species and functional richness than impaired wetlands at local scale, while impaired wetlands have higher beta diversity than protected wetlands. In protected wetlands, replacement contributed more than richness differences to both taxonomic and trait-based beta diversity. In impaired wetlands, replacement and richness differences contributed similarly to taxonomic-based beta diversity, but trait-based beta diversity was primarily driven by richness differences. Spatiotemporal variables played a crucial role in shaping aquatic insect assemblages in both protected and impaired wetlands. The null model suggested that aquatic insect assemblages in protected wetlands were mainly driven by dispersal limitation, whereas those in impaired wetlands were more shaped by environmental filtering. Wetland protection enhances the taxonomic and functional diversity of aquatic insects locally and alters community assembly at the regional scale. Our study emphasizes the need to consider different aspects of biodiversity and spatial scales when evaluating the effectiveness of wetland conservation. We highlight the importance of improving landscape connectivity between protected areas to enhance conservation outcomes and mitigate biodiversity loss in regions heavily modified by humans.