Which species will proliferate? Hong Kong as a coral acclimatization experiment for climate change

Abstract

While many species of corals within the Indo-Pacific region may not survive the onslaught of anthropogenic factors from climate change and urbanization, some few may have the capacity to acclimate or adapt to subtropical climates and coastal development. This study documents the thermal and photosynthetic performances of five species of symbiotic corals occurring across a gradient of increasing distribution within the Hong Kong SAR. We found that coral species exhibiting more restricted ranges such as Acropora digitifera and Galaxea fascicularis both exhibit heightened productivity and photosynthetic capacity when temperatures are below 25°C and ambient light is less than 150µmol m -2 s -1 . Conversely, we found that species found in abundance throughout Hong Kong such as Porites lobata and Oulastrea crispata show no signs of a thermal maximum for their productivity or photosynthetic capacity. We present this as evidence that these species have completely acclimated to a habitat which undergoes huge seasonal temperature fluctuations.