Banca de QUALIFICAÇÃO: WILDNA FERNANDES DO NASCIMENTO

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : WILDNA FERNANDES DO NASCIMENTO
DATE: 18/03/2023
TIME: 14:00
LOCAL: Departamento de Oceanografia e Limnologia
TITLE:

Mass coral bleaching in shallow reefs of Northeast Brazil following a major heatwave

KEY WORDS:

Climate changes; Marine Heatwave; coral bleaching.

PAGES: 29
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Marine heatwaves are becoming more frequent and intense and are considered one of the major causes of reef degradation. Coral reefs in Southwestern Atlantic have suffered less thermal-stress events compared to the Indo-Pacific and Caribbean, but this scenario has changed in the last decade as the region has been hit by some bleaching events. In 2020, the Brazilian northeast was affected by one of the biggest marine heatwaves in recent years, causing a bleaching never seen before in the region reached 16.86°C-weeks, the highest value since records began in 1985. We monitor the health of corals throughout this event, in the reefs of Rio do Fogo - RN. We want to understand whether the impacts caused by the heat wave vary between coral species and are influenced by morphological attributes such as colony size. We assessed coral health using the Coral Watch Coral Health Chart through photos along 5 transects. We evaluated the health of the stony corals Agaricia agaricites, Favia gravida, Porites astreoides, Siderastrea stellata and the zoanthids Palythoa caribaeorum, Palythoa grandiflora, Palythoa variabilis and Zoanthus sociatus. We observed that the stony corals showed a high level of bleaching when the heat wave was at its highest (April and May) and the species P. astreoides and S. stellata were able to recover their healthy color in about two months. The  opposite was observed for A. agaricites and F. gravida, which presented coverage losses of 100% and 90% respectively. In the case of zoanthids, the species remained stable. We observed that small colonies (< 5cm²) of S. stellata (dominant coral) showed greater sensitivity to the heat event, bleaching before larger colonies. In the period when the heat wave was most severe, more than 85% of the number of colonies of all classes showed signs of bleaching, with a decline in this value after the fall in DHW. Thus, coral species should remain stable after bleaching events,  lthough less abundant species have not recovered, which can cause loss of coral diversity, threatening the coral fauna that is highly endemic in these areas. 

COMMITTEE MEMBERS:
Externa à Instituição - BARBARA RAMOS PINHEIRO - UFAL
Presidente - 2319234 - GUILHERME ORTIGARA LONGO
Interna - 2412921 - JULIANA DEO DIAS