Banca de QUALIFICAÇÃO: HENRIQUE DOUGLAS DOS SANTOS BORBUREMA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : HENRIQUE DOUGLAS DOS SANTOS BORBUREMA
DATE: 24/05/2021
TIME: 14:00
LOCAL: Sala Virtual - Google Meet
TITLE:

EFFECTS OF GLOBAL CHANGE SCENARIOS ON THE PHYSIOLOGY OF ECOTYPES OF Bostrychia (RHODOPHYTA) FROM GENETICALLY DIVERGENT POPULATIONS

KEY WORDS:

 antioxidant activity ; carbohydrates ; estuaries ; growth ; mangroves ; ocean acidification  ; ocean warming ; pigmen content  ; proteins ; sea level rise

PAGES: 128
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Increasing greenhouse gas concentrations into the Earth’s atmosphere (mainly CO₂) have been causing global change. Environmental shifts are expected in estuarine ecosystem due to global change. Macroalgae in these ecosystems are primary producers which can mitigate global change by the CO₂ uptake toward photosynthesis, since they are tolerant to the environmental changes. So, we analyzed several physiological responses of B. montagnei and B. calliptera from two mangroves in Brazilian biogeographic realms (Tropical Atlantic -TA, and Temperate South America - TSA) after being cultivated in a bioreactor system at three fluctuating pH (7.2 ± 0.1, 7.6 ± 0.2 and 8.0 ± 0.2), being two decreased pH by CO₂ increment into the seawater (article I); and under increased temperature and salinity (article II). The established temperatures followed climatic models and the salinities were according to recorded salinities in the algal collection sites. Algae from both localities increased their productivity (growth as a proxy) in treatments of decreased and fluctuating pH. Overall, physiological responses of the algae were not negatively affected by decreased pH. Algae from TA had highest growth at 27 ºC and 15 PSU, and algae from TSA at 24 ºC and 15 PSU. Algae from TSA decreased their growth under increasing temperature and salinity. 34 ºC was a lethal temperature for algae from TA, whereas 29 and 31 ºC at 35 PSU were lethal for B. calliptera from TSA. Overall, increased salinity decreased effective quantum yield and relative electron transport rate in algal photosynthesis. Our results demonstrated that B. montagnei and B. calliptera mainly biosynthesize proteins, carbohydrates and antioxidant compounds to tolerate detrimental temperatures and salinities, and that their pigment content is adjusted for an efficient light-harvesting. Our study indicates that the analyzed algae are relevant for blue carbon in mangroves, contributing to mitigate global change, as they increased their productivity under increased availability of CO₂ (article I). We also demonstrated that ocean warming and increased salinity in the estuaries, because of sea level rise and displacement of the salt wedge, can be detrimental for the analyzed algae, compromising their ecological functions in mangroves (article II). We found still that the macroalgal populations are genetically and phenotypically divergent by molecular (DNA barcode COI-5P) and physiological data (article III).

BANKING MEMBERS:
Presidente - 1279472 - ELIANE MARINHO SORIANO
Interna - 2412921 - JULIANA DEO DIAS
Externo ao Programa - 363.178.178-47 - EDSON APARECIDO VIEIRA FILHO - UFRN