The community stability of Symbiodiniaceae and bacteria of different morphological corals and linkages to coral susceptibility to anthropogenic disturbance

Variously shaped corals, such as branching and massive corals, exhibit divergent environmental susceptibility properties. The susceptibility potential of these corals may be regulated by specific symbiotic Symbiodiniaceae and bacteria. In this study, we investigated seawater characteristics between the north and south zones at the Wuzhizhou Island (WZZ), sampled branching coral Acropora hyacinthus, lamellar coral Montipora informis, and massive coral (Galaxea fascicularis and Porites lutea). Physiological characteristics were measured, and amplicon sequencing was performed to Symbiodiniaceae and bacterial community structure analysis. Corals experienced severe anthropogenic disturbance, with more than 1.4-fold increase in DIN, including \({{\text{NH}}}_{4}^{+}\), \({{\text{NO}}}_{3}^{-}\), and \({{\text{NO}}}_{2}^{-}\) in the north of the WZZ Island compared to the southern region. However, massive corals (G. fascicularis and P. lutea) showed relatively less disruption in both their symbiont composition and physiological responses. Notably, M. informis displayed distinct variations, with disturbances in the northern region resulted in a decline in the density of symbiotic micro-algae associated with Cladocopium sp. C26 due to elevated concentrations of ammonium and nitrate. The four coral species hosted different symbionts within the same area. P. lutea hosted Cladocopium sp. C15 with the lowest density of symbiotic micro-algae, along with the lowest Fv/Fm and YII values compared to other corals in the southern zone. G. fascicularis exhibited high abundance of Durusdinium sp. D1 and D4, which showed strong correlation with Fv/Fm. In southern M. informis, Cladocopium sp. C26 was identified as the predominant symbiotic micro-algae that displayed a significant positive correlation with YII. The bacterial community composition and metabolism functional attribution predicted by PICRUSt differed between A. hyacinthus, M. informis, and massive corals (G. fascicularis, P. lutea). Comprehensive analysis revealed different susceptibility properties among branching, lamellar, and massive corals under anthropogenic disturbance associated with changes in Symbiodiniaceae and bacterial community.