Amphipods (Gammarus sp.) were observed and collected from the Tule Red Tidal Restoration Site in Suisun Marsh (38.117843, -121.983199) in January-December 2021. All observations and collections were conducted in <20 cm of brackish water in secondary tidal channels on the restoration site within 0.25 miles of the provided GPS coordinates. All amphipods were collected under California Scientific Collecting Permit No. S-201970002-20281-001. Monthly field observations and captures were done at 5m intervals over eight semi-permanent 20 m transects established in paired Phragmites and native plant canopies in the same area of the marsh, where 0m indicated the edge of a tidal channel. We measured pelagic invertebrate biodiversity by capturing discrete water pools (~60 g water) using a turkey baster. The water samples were sieved using a 0.125 mm filter and rinsed with deionized water before preservation in a rose bengal-dyed 70% ethanol solution. We also measured benthic invertebrate biodiversity with a sediment mud core (5 cm diameter and 10 cm depth). The benthic samples were sieved and washed using a 0.5 mm filter and rinsed with deionized water before preservation in a rose bengal-dyed 70% ethanol solution. Preserved samples were sorted, counted, and photographed under a dissecting microscope. Counts per sample were normalized to the weight of the original sample.

Funding:* Community function under Phragmites invasion in Suisun Marsh (https://www.seacrlab.com/), Award: Delta Stewardship Council DSF R/SF-107