Meeting Abstract
Ultraviolet radiation (UVR) composed of ultraviolet A (UVA: 320-400 nm) and ultraviolet B (UVB: 280-320 nm) can penetrate up to 30 m into the water column. Jellyfish are often considered robust to environmental stressors, which could explain localized increases in jellyfish blooms. To test resilience to UVR stress, this study exposed Aurelia aurita polyps to artificial UVA and UVB radiation (both isolated and combined) to determine the effects on asexual reproduction and potential mitigating mechanisms. There was no difference in reproduction between polyps exposed to isolated UVA (379.68 nm = 11.3 uWcm-2) and polyps that did not receive UVR. Polyps asexually reproduced when exposed to short term (~7-9 days) isolated UVB (305.22 nm = 8.7 uWcm-2), but long-term exposure limited reproduction and attachment. When exposed to both UVA (11.6 uWcm-2) and UVB (8.6 uWcm-2), polyps did not reproduce and experienced 100% mortality within 20 days. Furthermore, A. aurita polyps do not appear to have chemical or behavioral mechanisms to combat UVR exposure. Polyps did not contain mycosporine-like amino acids (MAAs) which absorb UVB radiation and have been found in other aquatic organisms. Polyps also did not sequester carotenoids (antioxidants) from their brine shrimp (Artemia sp.) diet. When exposed to combined UVA and UVB in the presence of a nearby UVR refuge, polyps did not migrate to the refuge. These results suggest that polyps lack mechanisms to alleviate UVR stress, so the planula larvae stage must be important for settlement away from UVR to establish the success of the polyp stage. Importantly, studies that only examine impacts of UVB potentially underestimate the full effect of UVR.
