Tidal influence on a fringing mangrove intertidal fish community as observed by in situ video recording: implications for studies of tidally migrating nekton

The vegetated intertidal zone has long been acknowledged as an important habitat for fish, but our understanding of the dynamics of intertidal migrations by these fish is limited. Using in situ video recordings, we examined fish movements into and out of the waterward margin of a fringing mangrove forest during spring tides at 27 haphazardly chosen sites throughout the Rookery Bay National Estuarine Research Reserve, Florida. Our results indicate that fish respond to tide stage in a species-specific manner. Based on the changes in relative abundance throughout the tide cycle, we identified 4 general intertidal migration patterns: (1) tide-level proportionate, with greatest abundance during high tide; (2) flood- and ebb-tide concentrated, with lowest abundance during high tide; (3) peak abundance at ebb and low tide; and (4) depth-limited but tidally independent. Given that the distribution of the fish within the intertidal zone was heterogeneous, we suggest that the placement of sampling gear within the intertidal zone and the timing of samples within the tide cycle can greatly influence the species composition of fish inventories.