Although anthropogenic inﬂuences such as global warming, overﬁshing, and eutrophication may contribute to jellyﬁsh blooms, little is known about the effects of ocean acidiﬁcation on jellyﬁsh. Most medusae form statoliths of calcium sulfate hemihydrate that are components of their balance organs (statocysts). This study was designed to test the effects of pH (7.9, within the average current range, 7.5, expected by 2100, and 7.2, expected by 2300) combined with two temperatures (9 and 15°C) on asexual reproduction and statolith formation of the moon jellyﬁsh, Aurelia labiata. Polyp survival was 100% after 122 d in seawater in all six temperature and pH combinations. Because few polyps at 9°C strobilated, and temperature effects on budding were consistent with published results, we did not analyze data from those three treatments further. At 15°C, there were no signiﬁcant effects of pH on the numbers of ephyrae or buds produced per polyp or on the numbers of statoliths per statocyst; however, statolith size was signiﬁcantly smaller in ephyrae released from polyps reared at low pH. Our results indicate that A. labiata polyps are quite tolerant of low pH, surviving and reproducing asexually even at the lowest tested pH; however, the effects of small statoliths on ephyra ﬁtness are unknown. Future research on the behavior of ephyrae with small statoliths would further our understanding of how ocean acidiﬁcation may affect jellyﬁsh survival in nature.
Winans, A. K. & Purcell, J. E., 2010. Effects of pH on asexual reproduction and statolith formation of the scyphozoan, Aurelia labiata . Hydrobiologia 645:39–52. Article (subscription required).