The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

Coral reefs are biodiverse ecosystems and highly sensitive to various stressors. Under these pressures, many habitat-forming species, including corals, anemones, and sponges, have undergone significant changes such as bleaching, mortality and phase shift. These changes may trigger cascading effects through symbiotic interactions, leading to shifts in their partners. It remains unclear whether habitat-forming species will amplify or buffer climate change impacts on their symbiotic partners. In this study, we focused on two typical macro-symbiotic relationships in coral reefs: coral-coral crab and anemone-clownfish. Our goal was to explore whether various habitat-forming species will produce different outcomes in predicting present as well as future species distribution. To address this, we constructed two types of models: abiotic-only and abiotic-plus-biotic for crabs and clownfish, separately. These models encompassed 30 obligate symbiotic interactions between six coral species and 10 crab species, as well as 58 interactions between 10 sea anemone species and 21 clownfish species. Our results revealed that the loss of habitat for crabs and anemones was concentrated in the Central Indo-Pacific, with corals showing greater sensitivity to climate change and experiencing larger range losses compared to anemones. In the future, the distribution ranges of coral crabs and clownfish were projected to contract further when symbiotic relationships were taken into account. In particular, coral hosts tend to amplify the negative impacts of climate change on their symbiotic species, while anemone hosts buffer these effects. Moreover, as the complexity of symbiotic relationships (host numbers for each symbiont) increases, the habitat ranges of symbiotic species tend to be more stable in response to climate change. In summary, we emphasize the importance of considering host specificity and the complexity of symbiotic relationships when predicting species distribution. We hope this approach will offer valuable insights for the future conservation of marine life.

species distribution models, symbiotic relationship, cascading effects, coral reefs, climate change, sea anemone