Physiological niches of cryptic coral species (Pocillopora spp.) in Moorea, French Polynesia
摘要
Coral species that cannot be reliably delineated in the field based on morphological characteristics are being increasingly detected using genetic approaches, but analyses of their functional biology have not kept pace with the rate at which they are being discovered. We genetically identified cryptic species of Pocillopora in Moorea French Polynesia (–17.481N, –149.8360W) and tested for differences in their physiological niches using two separate experiments conducted in April/May of 2022 and 2023. For corals from 12-m depth on the fore reef, the growth rates of P. meandrina were unaffected by temperature (26.1 vs 28.8 °C) but for P. tuahiniensis, growth rates were elevated at 28.8 °C versus 26.1 °C. In both species, growth rates increased with greater quantities of light (photon flux density [PFD] from 198–793 µmol photons m−2 s−1). Dark respiration exhibited a hump-shaped relationship with light at 26.1 °C but gradually increased with light at 28.8 °C. Net photosynthesis declined with light at both temperatures. For P. verrucosa from 2–3 m depth in the back reef, growth rates were unaffected by increasing temperature (25.2–30.9 °C) and light (131–1,156 µmol photons m−2 s−1), but the maximum photochemical efficiency of open reaction centers in photosystem II (Fv/Fm) declined with elevated temperature and high light. These morphologically similar species therefore are physiologically unequal, giving rise to the potential for portfolio effects within the Pocillopora spp. coral community to facilitate beneficial responses to changing conditions.