Tidal water exchange drives fish and crustacean abundances in salt marshes

Coastal salt marshes provide important habitat for fishes and crustaceans, including species of commercial value that feed or take refuge in the marsh. Yet population abundances vary considerably between sites, often without clear explanation. We hypothesised faunal abundance mean size would be positively related to 2 physical properties govern marsh accessibility water-dependent species, as has been found on southeastern coast USA: (1) volume water exchanged by tidal flooding, which gives access marsh, (2) edge amount, length water-vegetation borderline per unit area where can feed. Digital terrain models information were used select 5 Wales, UK, differed amount exchange (52°N, 4°W). Fishes crustaceans sampled using baited traps, fyke nets seine nets. In total, 15 caught, commercially valuable brown shrimp, European eel sea bass. volume, but not boosted fish crustacean abundances. Crab bass sizes both negatively affected exchange, while shrimp unaffected. Our findings show how mechanisms drive geographical regions. Feasibly, fisheries associations with hydrogeomorphology might operate differently well.