Amphipods were collected from the Tule Red Tidal Restoration site in Suisun Marsh, CA (38.117843, -121.983199) in July 2021. Using fine mesh nylon aquarium nets, adult amphipods (>0.5 cm in length) collected from a small channel and held in water-filled coolers. 24 individuals were collected for two habitat types (under native vegetation, under Phragmites vegetation) and immediately frozen on dry ice in the field to be used as controls in the following biochemical assays (below as "Week 0"). Collection and transport to the UC Davis Center for Aquatic Biology and Aquaculture were completed in <5 hours. Amphipods were housed in closed-system aquaria manually fed by marsh water collected at the mouth of the same tidal marsh (38.133841, -121.995977). In the lab, the marsh water was held in a darkened 1500 l sump tank and continuously aerated to reduce excessive algal growth (salinity = 6.3 psu). We randomly placed 120 amphipods into each of 16 tanks (n = 1,920 total). They were acclimated in common garden conditions at 15 °C for two days before experimental conditions were imposed for a 6-week laboratory acclimation period. In a fully crossed design, we exposed four replicate tanks each to the following four combinations of light and temperature exposure: native temperature/native light, native temperature/Phragmites light, Phragmites temperature/Phragmites light, and Phragmites temperature/native light. Amphipods were fed shrimp food pellets (Sera Shrimps Natural Nature Food) ad libitum three times per week. 50% of the water volume in each tank was replaced weekly using 0.125 mm filtered water from the 1500 l sump tank. Every two weeks during the 6-week acclimation period, 16 adults were randomly selected from each tank and sorted into two groups for protein and glycogen analyses (n = 8 for each analysis). Individuals were sacrificed in dry ice and stored at -80 °C. Prior to the homogenization of tissues, the presence/absence of eggs was recorded for each amphipod selected. The total number of juvenile amphipods in each tank was counted at the time of random selection.

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