Topographic heterogeneity influences fish use of an experimentally restored tidal marsh.

Ecological theory predicts that incorporating habitat heterogeneity into restoration sites should enhance diversity and key functions, yet research is limited on how topographic heterogeneity affects higher trophic levels. Our large (8-ha) southern California restoration experiment tested effects of tidal creek networks and pools on trophic structure of salt marsh habitat and high-tide use by two regionally dominant fish species, California killifish (Fundulus parvipinnis) and longjaw mudsucker (Gillichthys mirabilis). We expected tidal creeks to function as "conduits" that would enhance connectivity between subtidal and intertidal habitat and pools to serve as microhabitat "oases" for fishes. Pools did provide abundant invertebrate prey and were a preferred microhabitat for F. parvipinnis, even when the entire marsh was inundated (catch rates were 61% higher in pools). However, G. mirabilis showed no preference for pools. At a larger scale, effects of tidal creek networks were also mixed. Areas containing creeks had 12% higher catch rates of G. mirabilis, but lower catch rates and feeding rates of F. parvipinnis. Collectively, the results indicate that restoring multiple forms of heterogeneity is required to provide opportunities for multiple target consumers.