February 1st to 5th 2016
Olhão, Portugal
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Larvae of coral eating crown of thorns starfish, Acanthaster planci in a warmer-high CO2 ocean.

Scientific Exhibition
Future Oceans
Wednesday, February 3, 2016 -
18:30 to 20:00

Kamya, P. 1 Dworjanyn, S.A. 2 Byrne, M. 3

1National Marine Science Centre, Southern Cross University, Australia
2National Marine Science Center, Southern Cross University, Australia
3University of Sydney

Outbreaks of coral eating crown-of-thorns starfish (COTS),Acanthaster planci, contribute to major declines of coral reef ecosystems throughout the Indo-Pacific. Oceans are predicted to warm and decrease in pH due to increased anthropogenic CO2 production, making coral reefs susceptible to bleaching, disease and reduced calcification. While corals are expected to continue to decline under predicted ocean warming and acidification it is not known how its major predator will fare in a changing ocean. Because larval success is a key driver of population outbreaks, this study investigated the sensitivities of larval A. planci to increased temperature (2–4 °C above ambient) and acidification (0.3–0.5 pH units below ambient) in flow-through cross-factorial experiments (3 temperature X 3 pH/pCO2 levels). There was no effect of increased temperature or acidification on fertilization or very early development. Larvae reared in the optimal temperature (28 °C) were the largest across all pH treatments. Development to advanced larva was negatively affected by the high temperature treatment (30 °C) and by both experimental pH levels (pH 7.6, 7.8). Increased temperature and reduced pH had an additive negative effect on reducing larval size. The 30 °C treatment exceeded larval tolerance regardless of pH. Thus, planktonic life stages of A. planci may be negatively impacted by near-future global change. As oceans continue to warm, A. planci populations may move to higher latitudes following optimal temperature gradients. It is important to investigate later life stages, particularly the early benthic juvenile to assess prospects for A. planci populations in a changing ocean.
keywords: 
coral reefs, Crown of thorns starfish, larvae, ocean acidification, ocean warming

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