As the ocean warms, the thermal tolerance of marine invertebrates is key to determining their distributional change, where acclimation to low pH may impact the thermal range of optimal development. We compared thermal tolerance of progeny from a low pH-acclimated sea urchin (Arbacia lixula) population from the CO2 vents of Ischia (Italy), and a nearby population living at ambient pH. The percentage of normally developing gastrulae and two-armed larvae were determined across 10 temperatures representing present and future temperature conditions (16-34 ˚C). Vent-acclimated sea urchins showed a greater percentage of normal development at 24 hours, with a larger optimal developmental temperature range than control sea urchins (12.3 ˚C vs 5.4 ˚C range, respectively). At 48 hours, upper lethal temperatures for 50% survival with respect to ambient temperatures were similar between control (+6.8 ˚C) and vent (+6.2 ˚C) populations. Thus, acclimation to low pH did not impact the broad thermal tolerance of A. lixula progeny. With A. lixula’s barrens forming abilities, its wide thermotolerance and its ability to acclimate to low pH, this species will continue to be an important ecological engineer in Mediterranean macroalgal ecosystems in a changing ocean.

The dataset contains percentage normal data (“Percent Normal”) for 24 hours and 48 hours (“Time (hours)”) A. lixula progeny raised under 10 different temperatures (“Temperature (celsius)”). Data for three separate male-female crosses (“Cross”), and two different populations (“Population”) are provided. Data for each individual replicate (“Replicate”) and temperature are shown. Please see methods from corresponding publication for how the data was collected and processed. Please cite the relevant paper if using the dataset.