Dataset: Menidia embryo thermal tolerance

On 10 June (Exp1) and 24 June 2026 (Exp2), we caught spawning ripe Atlantic silversides (Menidia menidia) in a small nearby cove (Mumford Cove, CT), using a 33 × 2 meter (m) beachseine. The fish were transported live to the University of Connecticut's Rankin seawater lab and kept there in aerated tubs at ~21°C overnight. On 11 June (Exp1) and 25 June (Exp2) at 3 PM, we strip-spawned 28 females and 52 males (Exp1: 28 fem – 52 male; Exp2: 25 fem – 36 male) to produce ~ 15,000 embryos per experiment. Embryos were spawned onto plastic window screen (1-millimeter (mm) mesh), then screens were cut into small pieces where we counted the number of fertilized embryos (15 – 35). We did this 255 times for each experiment; 5 screens (replicates) for each of 5 exposure temperatures, 5 exposure durations, and 2 exposure time points = 5 x 5 x 5 x 2 = 250. 5 screens served as controls (no exposure). For temperature exposures, embryos were transferred from the control tank to glass aquaria equipped with temperature controllers and 800W aquarium heaters. Onset HOBO loggers were used to record temperatures at 5 minute intervals.