This data was gathered to study the effects of combined environmental stressors of lowered pH and increased temperature on the adult metabolism and larval development of the Antarctic sea urchin, S. neumayeri. Specimens were cultured under the combined environmental stressors of lowered pH (-0.3 and -0.5 pH units) and increased temperature (+2 degrees C). The experiment took place over a two-year period, from June 2009, covering two full reproductive cycles of this species. The dataset is divided into adult and offspring. Data for adult S. neumayeri are given at four-monthly intervals. Values provided include oxygen consumption (umols), whole animal wet and dry mass (g), test diameter and thickness (mm), gonad wet and dry tissue mass (g), AFDM (Ash-Free Dry Mass) (g), CaCO3, and gonad index (GI%). Mean frequencies are also provided for larval development stages (%) for 25-day-old S. neumayeri offspring. These offspring are derived from larval cultures spawned after 6 and 17 months exposure to altered pH and temperature conditions. Postoral arm length measurements for the most advanced larvae is also provided as a metric of skeletal development. Two tables relating to seawater chemistry measurements are also provided. Table 1 displays mean water parameters in the adult S. neumayeri microcosm over the course of the experiment. Supplementary Table 1 gives mean seawater parameters of the S. neumayeri larval cultures derived from parents pre-exposed to low temperature and high temperature seawater controls and lowered carbonate conditions.

This dataset set describes the developmental stages and the molecular barcoding of Terebellidae larvae identified from diver-collected samples on 2021-04-22 in Ryder Bay near Rothera Research Station, Antarctic Peninsula, Antarctica. Photographs were collected at seven stages across the larval development. Development was captured from the trochophore stage where the polychaete larvae were bound in mucus to the free swimming planktonic metatrochophore to the nectochaete stage. Molecular barcoding was performed using the 18S rRNA gene at the British Antarctic Survey. Funding: This study was funded by core funding to UKRI NERC-BAS.