Experimental evolution of the coral algal endosymbiont, Cladocopium goreaui: Lessons learnt across a decade of stress experiments to enhance coral heat tolerance

Published source details Quigley K.M., Alvarez Roa C., Beltran V.H., Leggat B. & Willis B.L. (2021) Experimental evolution of the coral algal endosymbiont, Cladocopium goreaui: Lessons learnt across a decade of stress experiments to enhance coral heat tolerance. Restoration Ecology, 29, e13342.
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This study is summarised as evidence for the following.

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	Cultivate corals in an ex-situ nursery Action Link

Cultivate corals in an ex-situ nursery

A replicated, randomized, controlled study in a laboratory in Australia (Quigley et al. 2021) reported 69–96% survival of cultivated corals Acropora tenuis over 28–72 days, depending on the temperature and type of symbiont added. At 27°C, survival was lower for corals with heat tolerant symbionts (89%) than for those with natural symbionts (95%) after 28 days, but similar after 72 days (heat tolerant: 80%, natural: 87%). At 31°C or 32.5°C, survival was similar for both types of symbiont at 28 days (93–96%) and 72 days (69–82%). For two measures of growth, corals with heat tolerant symbionts had lower growth than those with natural symbionts in five of 10 comparisons across three temperatures. The study also reports results on symbiont density and performance. Symbiont cells were extracted from wild corals and a heat tolerant strain was developed over 21 generations in laboratory conditions. A mixture of natural strains was also obtained. Coral larvae were settled on aragonite plugs (1,628 plugs), and following uptake of symbionts, transferred to tanks (9 with heat tolerant symbionts, 9 with natural symbionts). Tanks were split evenly between three temperature treatments (27, 31, 32.5°C). Survival and growth were assessed after 28 and 72 days.

(Summarised by: William Morgan)