AFSC/RACE/SAP/Foy: The effects of ocean acidification on ovigerous Tanner crab size, calcium, and magnesium content. : Kodiak Island, Alaska.

To study the effects of ocean acidification we conducted laboratory experiments with adult ovigerous females of the economically important southern Tanner crab, Chionoecetes bairdi.
Ovigerous females were reared in one of 3 treatments: control (ambient pH ~8.1), pH 7.8, and pH 7.5 for 2 years. The adult female sizes used for the experiments ranged from 87 to 112 mm
among the three treatments. Throughout the experiment , pH and temperature were measured daily in each of the 3 treatments. The mean daily temperature was 5.0 C, varied seasonally from
a low of ~1 C in January 2012 to a high of ~ 9C in August 2011, and did not vary between treatments. pH remained significantly different among the treatments. Brooding duration for each
female was defined as beginning the day of egg extrusion in 2012 and ended when larval hatching began in 2013. Mean brood duration ranged from 340 to 366 days. Magnesium and calcium content
were determined at the end of the experiment from a portion of exoskeleton. Magnesium did not differ with pH treatment but the ratio of magnesium to calcium did differ among treatments.