Banca de DEFESA: BRUNA SANTANA DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : BRUNA SANTANA DA SILVA
DATE: 27/02/2026
TIME: 14:00
LOCAL: Google Meet (meet.google.com/ mwn-bbzw-qyp)
TITLE:

Temporal variations of the carbonate system and indicators of reef metabolism in the context of ocean acidification

KEY WORDS:

Carbonate; Aragonite saturation state; CO₂ fluxes; Ocean Acidification; Climate change

PAGES: 47
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Coral reefs are among the ecosystems most vulnerable to global climate change, especially to ocean acidification, which alters the carbonate system and compromises the calcification of reef organisms. The increase in CO₂ emissions intensifies its dissolution in the oceans, reducing pH and modifying fundamental biogeochemical processes. This study evaluated the carbonate system and CO₂ fluxes in the Parrachos de Rio do Fogo (RN) based on six expeditions carried out between May 2024 and May 2025, covering both dry and rainy periods. Physicochemical parameters, nutrients, and carbonate system variables were analyzed. During the rainy period, lower pH (7.862 ± 0.049) and salinity (33.743 ± 1.010) values were recorded, along with higher temperatures (30.476 ± 0.527 °C),higher nutrient concentrations, and higher dissolved CO₂ levels (18.09 ± 2.73 µmol L ¹), ⁻indicating greater continental influence and intensified respiration and decomposition oforganic matter. The highest total alkalinity values (up to 2350.70 ± 16.59 µmol kg ¹) ⁻ suggest CaCO₃ dissolution associated with the input of more acidified waters. During the dry period, lower levels of dissolved CO₂ and nutrients and a reduction in total alkalinity(2075.28 ± 31.15 µmol kg ¹) were observed, indicating greater calcification and a ⁻predominance of internal reef processes. Principal component analysis explained 70% of the environmental variability. The %NCP index (66.3%) indicated that the reef acts as a CO₂ sink during the dry period (net autotrophy) and as a source during the rainy period (net heterotrophy). During the rainy season, aragonite saturation frequently fell below theideal level for calcification ( arag < 3). The results highlight strong seasonal variation in Ωthe reef metabolism of the Parrachos de Rio do Fogo and its vulnerability to climate change and increased continental input

COMMITTEE MEMBERS:
Externa à Instituição - BARBARA RAMOS PINHEIRO
Presidente - 3257898 - Cybelle Menolli Longhini
Externa ao Programa - 3499682 - KELLY YUMI INAGAKI - null