Highlights
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Deoxygenation enhanced the survival of the creeping polyps of Alatina alata.
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More creeping polyps settled under low pH and low dissolved O2 (DO) treatments than under normal pH and DO conditions.
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Exposure to low pH and DO did not influence the number of tentacles, mobility or movement velocity of the creeping polyps.
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The Irukandji jellyfish may persist in coastal areas with coastal deoxygenation and acidification.
Abstract
Deoxygenation and acidification co-occur in many coastal ecosystems because nutrient enrichment produces excess organic matter that intensifies aerobic respiration during decomposition, thereby depleting O2, increasing CO2 and lowering pH. Despite this link between coastal deoxygenation (CD) and acidification (CA), and evidence that both stressors pose a risk to marine fauna, few studies have examined the effects of these drivers in combination on marine animals including invertebrates. Here, we studied the individual and combined effects of CD (∼1.5 mg L−1 O2) and CA (∼7.7 pH) on the survival, number of tentacles, settlement and movement behaviours of creeping polyps of the Irukandji jellyfish, Alatina alata. Low DO increased the survival rate (17% more) of the creeping polyps. 12% more creeping polyps settled in low pH than ambient pH and 16.7% more settled in low DO than ambient DO treatment. Exposure to CA and CD did not influence the number of tentacles, mobility or movement velocity of the creeping polyps, but after 4 h exposure to the treatments, they moved approximately half as fast. Our results indicate that CD can enhance survival and settlement success, but CA does not intensify these outcomes on A. alata creeping polyps.
Boco S. R., Pitt K. A. & Melvin S. D., in press. Coastal acidification and deoxygenation enhance settlement but do not influence movement behavior of creeping polyps of the irukandji jellyfish, Alatina alata (cubozoa). Marine Environmental Research. Article (subscription required).
