Ocean acidification: direct and indirect effects on the growth of Cyanea capillata and Chrysaora hysoscella polyps

• Main Authors: Algueró-Muñiz, Maria, Lesniowski, Thomas, Malzahn, Arne M., Boersma, Maarten
• Format: Conference Object
• Language: unknown
• Published: 2013
• Subjects: Ocean acidification
• Online Access: https://epic.awi.de/id/eprint/35357/; https://epic.awi.de/id/eprint/35357/1/IJBS2013malguero.pdf; https://hdl.handle.net/10013/epic.43350; https://hdl.handle.net/10013/epic.43350.d001

Ocean acidification (OA) is one of the major threats to our global oceans. It may affect biota directly by decreases in pH, as well as indirectly via trophic pathways. Obviously, most of the OA research has focused on calcifying organisms, but recently also other organisms have come under investigation. One of the prominent exceptions is gelatinous zooplankton, where very few published reports exist on the impact of OA. Hence, we set out to investigate the direct and indirect effects of OA (through CO2 induced changes in food quality) on the growth of polyps of two scyphozoans. Adult Cyanea capillata and Chrysaora hysoscella were harvested from the field, left to release larvae in the laboratory, and these left to settle and develop into polyps. Polyps were exposed to two different CO2 environments (200 and 800 ppm) and two food qualities which differed in their elemental composition. Subsequently, growth over an experimental period of 27 days was measured. We observed no significant differences between the two CO2 levels, whereas there was a clear impact of food quality on polyp’s growth. At least for this life stage, indirect effects of OA are more important than direct pH effects. Other life stages, especially those building statoliths may be more vulnerable, but the literature indicates that this is also not the case under realistic CO2 scenarios. Future research will have to incorporate all life stages to generate a comprehensive understanding of direct and indirect effects of OA on the gelatinous zooplankton.