Complex Tidal Marsh Dynamics Structure Fish Foraging Patterns in the San Francisco Estuary

Abstract Mechanisms driving the consumption and transport of tidal marsh nutrients energy by fishes are key interest in San Francisco Estuary, CA, USA. By combining multiple data sources (gill-net catches, gut contents, channel morphology, tides), we modeled spatial temporal patterns fish abundance fullness across a elevation gradient. Channel depth, microhabitat, tide were important predictors fullness. Species, feeding guild, season also to but not fullness, suggesting that was more related physical constraints shallow water than prey availability. Multiple guilds overlapped space time at interaction hotspots subtidal habitat near entrance. In contrast, use intertidal channels variable indicated tradeoffs between foraging predation. Gut content analysis revealed moderate-to-high for all models predicted high reaches during flooding, after which fed intensively throughout marsh. While mysids, amphipods, detritus common among guilds, variation apparent. Overall, complex hydrogeomorphology land-water exchange residence may diversify enhance benthic pelagic food web pathways invertebrates. Furthermore, these findings substantiate notion dynamic marshes this system can support robust secondary production, trophic transfer estuarine mosaic.