Integrating nekton communities, salt pool dynamics, and fish foraging patterns to assess salt marsh restoration success in Maritime Canada

Salt marsh restoration aims to recover areas and ecological functions that have been impacted by human activities. We evaluated different structural and functional metrics to assess the response of nekton to salt marsh restoration in two distinct case studies in Maritime Canada in 2022-2023. We compared the visiting nekton communities in intertidal creeks and on marsh platforms, the abiotic conditions and small-bodied faunal communities in salt pools, and the foraging patterns of two fishes between reference and restoring marshes. In both case studies, similar nekton species were observed between reference and restoring marshes; however, nekton communities differed by site type (14-52% of the variation). Pools in restoring marshes were providing basic nekton functions but had yet to offer the enhanced habitat support as those in reference marshes. Gut fullness was similar in tomcods (Microgadus tomcod) and mummichogs (Fundulus heteroclitus) between site types suggesting that restoring marshes were fulfilling foraging function for these species despite site type differences (11-44% of the variation) in prey composition being detected. Although the nekton community structure and functions in restoring marshes did not mirror those in references marshes, our findings highlight the value of restoring salt marshes in terms of nekton habitat. This study also demonstrates the advantages of implementing a multifaceted approach to understand the response of biotic communities to salt marsh restoration.