Trophic plasticity drives species-specific adaptive responses to seasonal variability in reef-building corals
摘要
While corals from high-latitude marginal reefs are hypothesized to possess enhanced stress tolerance, their acclimatization mechanisms to local environmental fluctuations, particularly seasonal light and temperature variations, remain incompletely characterized. This study investigated the trophic strategies of three coral species (Galaxea fascicularis, Pocillopora damicornis, and Acropora hyacinthus) on Luhuitou reef, a relatively high-latitude reef in China subject to pronounced seasonal shifts between rising-temperature, high-light springs and cooling-temperature, low-light autumns. We assessed trophic plasticity by integrating seasonal measurements of photosynthetic performance, energy reserve dynamics, and stable isotope signatures. Clear interspecific differences in seasonal responses were observed. By adopting a heterotrophically reliant dual assurance strategy, G. fascicularis increased both heterotrophic input and photosynthetic capacity, which together helped to counterbalance the loss in photosynthetic efficiency resulting from its elevated symbiont populations in autumn. Pocillopora damicornis relied on enhanced photosynthetic efficiency under baseline heterotrophy, optimizing light capture during low-light periods in autumn. Acropora hyacinthus maintained a mixotrophic strategy, exhibiting minimal seasonal shift and thus the lowest trophic flexibility among the studied species. These findings highlight that there is no single optimal strategy for highly variable reef systems, but rather that interspecific variation in trophic strategy is critical to community resilience under environmental change.