Connection over creation: hydrological connectivity drives post-restoration community assembly in coastal ponds

Abstract

Evaluations of wetland restoration have often focussed on the role that dispersal, environmental filters and/or spatial features play in new habitats. Success has generally been measured by comparing new habitats with reference sites. However, in coastal ponds, hydrological connectivity can determine environmental constraints as it can influence salinity, nutrient concentration, and connectivity strength. Based on these premises, we expect that hydrological connectivity should be a stronger determinant of community assembly following restoration. To test this hypothesis, we took advantage of a restoration project carried out in La Pletera salt marsh (NE Iberian Peninsula) and compared the effects of hydrological connectivity and pond age on community composition and functioning after restoration. Macroinvertebrate communities of 13 ponds (10 new and 3 old) were surveyed in 2016, 2017 and 2022. We analysed community changes over time by comparing nestedness, modularity, diversity, and similarity indices between pond categories and based on taxonomic and biological trait data. Our results showed that hydrological connectivity shaped two distinct communities. These findings underscore the central role of hydrology in community dynamics and highlight the importance of integrating hydrological connectivity into restoration strategies for coastal ponds