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Marine Ecology Progress Series

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MEPS 690:65-82 (2022)  -  DOI:

Effects of climate change and light limitation on coral recruits

Christopher A. Brunner1,2,3,*, Gerard. F. Ricardo2, Sven Uthicke2,3, Andrew P. Negri2,3, Mia O. Hoogenboom1

1College of Science and Engineering and Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811, Australia
2Australian Institute of Marine Science, Townsville, Queensland 4810, Australia
3AIMS@JCU, James Cook University, Townsville, Queensland 4811, Australia
*Corresponding author:

ABSTRACT: Climate change impacts and light attenuation from suspended sediments, due to runoff, natural resuspension or dredging, can both impede the replenishment of coral populations. Here we tested the independent and combined impacts of climate change (current temperature and dissolved CO2, and 2 future climate scenarios) and a 1 mo long light attenuation period at 5 different light levels (0.1 to 4 mol photons m-2 d-1) on early Acropora millepora recruits. Additionally, we evaluated whether the effects were age dependent by comparing responses of recruits that were 1 mo old (‘early attenuation’) vs. 2 mo old (‘late attenuation’). Recruit survival, size and Symbiodiniaceae densities increased slightly under moderate future climate conditions (current temperature +0.44°C, 692 ppm pCO2), but decreased under a more severe climate scenario (+0.94°C, 985 ppm pCO2). Light attenuation significantly decreased recruit survival, size and Symbiodiniaceae densities only for recruits exposed to the late attenuation, suggesting an increasing reliance on photosynthesis as recruits age. Under the more severe climate scenario tested, recruit survival was diminished by both climate change (≤18 ± 4% [SE] in the early attenuation) and light limitation (≤32 ± 6% in the late attenuation) compared with controls. However, there was no interaction between future climate scenarios and light attenuation, indicating that these effects were additive. This study demonstrates the potential effects of light limitation and future climate conditions on coral recruitment success and highlights the need to manage the timing of sediment-generating activities near reefs to optimise light availability for several months post settlement.

KEY WORDS: Water quality · Runoff · Sediment · Turbidity · Dredging

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Cite this article as: Brunner CA, Ricardo GF, Uthicke S, Negri AP, Hoogenboom MO (2022) Effects of climate change and light limitation on coral recruits. Mar Ecol Prog Ser 690:65-82.

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