Lengths were measured of calcareous skeletal rods, body length and stomach area. Growth and morphometrics of sea urchin larvae cultured at control pCO2 (400 µatm) vs. elevated pCO2 (900 µatm). Results are from larvae collected on days 11, 13, 15, and 17 (postfertilization) of trial 1.
Larval Culture of Sea Urchins: Adult urchins were collected from seven populations from Central Oregon to Southern California, spanning 1,200 km of the S. purpuratus species range, and were shipped to Bodega Marine Laboratory (see SI Text for complete experimental details). Adults were spawned in the laboratory, and for each population gametes were mixed from 10 females and 10 males. Fertilized embryos were cultured under present-day global-mean pCO2 (partial pressure of CO2∼400 µatm) and a fossil-fuel intensive projection (∼900 µatm) (48). After 24 h, hatched blastulae were transferred to four replicate jars per population and CO2 level, and were maintained at 14 °C in jars with oscillating paddles (SI Text). Seawater was exchanged and sampled for pH and alkalinity, and larvae were fed and sampled every other day during 50-d trials, from 3 d postfertilization to metamorphosis.
Related Reference:
Pespeni, M.H., E. Sanford, B. Gaylord, T. M. Hill, J. D. Hosfelt, H. Jaris, M. LaVigne, E. A. Lenz, A. D. Russell, M. K. Young, S. R. Palumbi. 2013. Evolutionary change during experimental ocean acidification. Proceedings National Academy of Sciences 110 (17): 6937-6942.
Pespeni supporting information with detailed methods: http://www.pnas.org/content/suppl/2013/04/04/1220673110.DCSupplemental/pnas.201220673SI.pdf#nameddest=STXT