Ecologia e Fisiologia - Pôsteres - 28/11/2023 - 15:30 h às 16:30 h

Coral and octocoral bleaching is characterized by the breakdown of the symbiotic relationship between animal host and endosymbiont photosynthetic microalgae. This phenomenon is mainly related to thermal stress conditions that increases reactive oxygen species production by the photosynthetic machinery. Under the context of climate change, an increase of ocean temperature up to 4.5 °C by 2100 could lead to bleaching and death of several coral reefs. In a moderate predictive scenario, we aim here to characterize coral and octocoral metabolic physiology in order to test whether high temperature triggers molecular damage and antioxidant capacity. Colonies (5 ≤ N ≤ 6) of the octocorals Plexaurella grandiflora and Neospongodes atlantica, and of the corals Madracis decactis and Tubastraea coccinea were submitted to a moderate predictive scenario of global warming (+3.5 °C), as well as kept in a control scenario (26°C), for 14 days, in an open system. For the present moment, the oxidative status was evaluated via total antioxidant capacity (TAC) and lipid peroxidation (LPO). The effects of ‘temperature’ and 'species' were assessed using two-way analysis of variance (ANOVA), followed by multiple comparisons test (SNK) if necessary. In summary, system temperature remained stable under both conditions (control: 26.0 ± 0.4°C; treatment: 29.4 ± 0.3°C). Heat treatment showed no effect on LPO and TAC levels, however 'species' affected such metrics. Tubastraea coccinea, an azooxanthellate species, showed the highest levels of TAC and lowest levels of LPO in both control and treatment conditions, whereas M. decactis showed the highest LPO levels, and was the only species with visual bleaching. Thus, exposure to high temperature did not affect the oxidative status in the representatives here evaluated, however the interspecific variability was significant between coral and octocoral species. We highlight here T. coccinea, an invasive species, with high physiological tolerance to thermal stress.