The dispersant Corexit 9500 and (dispersed) oil are lethal to coral endosymbionts

Tooba Varasteh; Michele S Lima; Tatiana A Silva; Maria Luíza R da Cruz; Reza Amir Ahmadi; Georgia C Atella; Marcia Attias; Jean Swings; Wanderley de Souza; Fabiano L Thompson; Cristiane C Thompson

doi:10.1016/j.marpolbul.2024.116491

The dispersant Corexit 9500 and (dispersed) oil are lethal to coral endosymbionts

Mar Pollut Bull. 2024 May 15:203:116491. doi: 10.1016/j.marpolbul.2024.116491. Online ahead of print.

Affiliations

¹ Laboratory of Microbiology, Biology Institute, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil.
² Laboratory of Celullar Ultrastructure Hertha Meyer, Biophysics Institute Carlos Chagas Filho, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil.
³ Laboratory of Lipids Biochemistry and Lipoprotein, Biochemistry Institute Leopoldo de Meis, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil.
⁴ Laboratory of Microbiology, Biology Institute, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil. Electronic address: fabianothompson1@gmail.com.
⁵ Laboratory of Microbiology, Biology Institute, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil. Electronic address: thompsoncristiane@gmail.com.

PMID: 38754321
DOI: 10.1016/j.marpolbul.2024.116491

Abstract

Endosymbionts (Symbiodiniaceae) play a vital role in the health of corals. Seawater pollution can harm these endosymbionts and dispersants used during oil spill cleanup can be extremely toxic to these organisms. Here, we examined the impact of oil and a specific dispersant, Corexit-9500, on two representative endosymbionts - Symbiodinium and Cladocopium - from the Southwestern endemic coral Mussismilia braziliensis. The survival and photosynthetic potential of the endosymbionts decreased dramatically after exposure to the dispersant and oil by ~25 % after 2 h and ~50 % after 7 days. Low concentrations of dispersant (0.005 ml/l) and dispersed oil (Polycyclic Aromatic Hydrocarbons, 1132 μg/l; Total Petroleum Hydrocarbons, 595 μg/l) proved highly toxic to both Symbiodinium and Cladocopium. These levels triggered a reduction in growth rate, cell size, and cell wall thickness. After a few hours of exposure, cellular organelles were damaged or destroyed. These acute toxic effects underline the fragile nature of coral endosymbionts.

Keywords: Cladocopium; Corexit; Lipidomics; Mussismilia braziliensis; Oil; Symbiodinium.