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. The expected trajectories of these restorations are still not fully characterized as they can be influenced by factors including pre-restoration state, hydrological conditions, and sediment supply. We evaluated the visiting nekton communities in intertidal creeks and on marsh platforms, the abiotic conditions and faunal communities in salt pools, and the foraging patterns of focal fishes in two salt marsh restoration projects (case studies) in Maritime Canada in 2022- 2023. These included: Aulac in the upper Bay of Fundy which was former pastureland on its 12th and 13th year of restoration, and Wallace Bay on the Northumberland Strait which was a former freshwater impoundment on its 2nd and 3rd year of restoration. Nekton community structure in creeks and on platforms and pool abiotic conditions and fauna differed between site types (i.e., restoring and reference established marshes) in both case studies. Prey composition of tomcods (Microgadus tomcod) and mummichogs (Fundulus heteroclitus) also differed between fish caught in restoring and reference sites, yet site type variations in gut fullness were only identified in platform mummichog in Wallace Bay. Our findings suggest that although nekton respond quickly to salt marsh restoration, functional differences in terms of habitat support exist after a decade of recovery. This study demonstrates the value of implementing a multifaceted approach to monitor the response of biotic communities to salt marsh restoration.