The effect of polychaetes infestation on calcification rates and morphological changes in reef-building coral Porites lobata

Morphological plasticity in hermatypic corals is an adaptive response that helps corals withstand biotic and abiotic stressors, but also, can influence the structural complexity of coral reef habitats. The influences of biotic factors (e.g., bioerosion) on coral plasticity may threaten the skeletal structure, reducing coral's ability to compete for space and survive. The present study reports intense infestation of Chaetopterids, a tube-dwelling polychaetes in Porites lobata colonies, and evaluates their effects on coral growth and morphology by comparing skeletal features (extension rate, skeletal density, and calcification rate) before and after polychaete outbreak. The results showed significant differences in all coral skeletal features of P. lobata before and after polychaete infestation. After-infestation, coral growth decreased an average of 42% and 46% in annual extension and calcification rates, respectively. Sclerochronology analysis displayed partial mortality and stress-signature bands, which coincided with the cold 2010-2011 La Nina period, when polychaete infestation was potentially initiated. The data reveals that P. lobata coral appears capable of modifying its growth strategy (optimal plasticity), yet polychaete infestation can negatively affect coral accretion rates and weaken coral structural stability, in turn compromising their long-term contribution to coral reef habitats maintenances in the eastern tropical Pacific.

Automated summary

Morphological plasticity in hermatypic corals is an adaptive response, but the infestation of tube-dwelling polychaetes can negatively affect coral growth and structural stability.