Ocean acidification impairs the physiology of symbiotic phyllosoma larvae of the lobster Thenus australiensis and their ability to detect cues from jellyfish

Ocean acidification (OA) can alter the behaviour and physiology of marine fauna and impair their ability to interact with other species, including those in symbiotic and predatory relationships. Phyllosoma larvae of lobsters are symbionts to many invertebrates and often ride and feed on jellyfish, however OA may threaten interactions between phyllosomas and jellyfish. Here, we tested whether OA predicted for surface mid-shelf waters of Great Barrier Reef, Australia, under Delta pH = -0.1 (pH similar to 7.9) and Delta pH = -0.3 (pH similar to 7.7) relative to the present pH (similar to 8.0) (P) impaired the survival, moulting, respiration, and metabolite profiles of phyllosoma larvae of the slipper lobster Thenus australiensis, and the ability of phyllosomas to detect chemical cues of fresh jellyfish tissue. We discovered that OA was detrimental to survival of phyllosomas with only 20% survival under Delta pH = -0.3 compared to 49.2% and 45.3% in the P and Delta pH = -0.1 treatments, respectively. The numbers of phyllosomas that moulted in the P and Delta pH = -0.1 treatments were 40% and 34% higher, respectively, than those in the Delta pH = -0.3 treatment. Respiration rates varied between pH treatments, but were not consistent through time. Respiration rates in the Delta pH = -0.3 and Delta pH = -0.1 treatments were initially 40% and 22% higher, respectively, than in the P treatment on Day 2 and then rates varied to become 26% lower (Delta pH = -0.3) and 17% (Delta pH = -0.1) higher towards the end of the experiment. Larvae were attracted to jellyfish tissue in treatments P and Delta pH = -0.1 but avoided jellyfish at Delta pH = -0.3. Moreover, OA conditions under Delta pH = -0.1 and Delta pH = -0.3 levels reduced the relative abundances of 22 of the 34 metabolites detected in phyllosomas via Nuclear Magnetic Resonance (NMR) spectroscopy. Our study demonstrates that the physiology and ability to detect jellyfish tissue by phyllosomas of the lobster T. australiensis may be impaired under Delta pH = -0.3 relative to the present conditions, with potential negative consequences for adult populations of this commercially important species. (C) 2021 Elsevier B.V. All rights reserved.