Banca de QUALIFICAÇÃO: CELIO FREIRE MARIZ JR

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE: CELIO FREIRE MARIZ JR
DATA : 31/01/2023
LOCAL: VIDEOCONFERÊNCIA
TÍTULO:

Toxicity of the oil spilled on the Brazilian coast at different stages of natural weathering to embryo-larval stages of the zebrafish Danio rerio

PALAVRAS-CHAVES:

Morphological alterations. PAH. WAF. Emulsified oil.

PÁGINAS: 20
RESUMO:

The Brazilian coast was affected by an oil spill that caused impacts on coastal aquatic ecosystems between 2019 and 2020. Toxicity based on developmental, morphological, biochemical and behavioral endpoints were measured in embryo-larval stages of Danio rerio exposed to polycyclic polycyclic aromatic hydrocarbons (PAH) in oil water accommodated fractions (WAFs) prepared from three oil samples with different levels of weathering. Masses of submerged emulsified oil as they reached Paiva Beach on October 3 rd , 2019, characterized oil mousse samples (OM). Two other samples were collected 50 days later at Ponta do Xaréu Beach, named oil in sand (OS) which was characterized by OM deposited on sand after reaching the supralittoral strip, and oil in rock (OR) characterized by OM that adhered to rocks on the shore. Significant changes in the relative concentration of parent and alkylated PAHs were verified in oil WAFs from the differentially weathered oil samples. Alkylated naphthalenes in less weathered WAF-OM represented 40.8% of total PAHs, and decreased to 15.9% and 6.2% in WAF-OS and WAF-OR, respectively, suggesting losses of alkylated 2 ring PAHs by evaporation after the emulsified oil reached the coast. Phenanthrene and alkylated phenanthrenes + anthracenes increased from 23.9% of total PAHs in WAF-OM to 43% and 46% in WAF-OS and WAF-OR, respectively. Increases in the proportion of 3, 4 and 5 ring parent and alkylated PAHs in WAF-OS and WAF-OR compared to WAF-OM were also verified. Zebrafish embryo- larval development until 96 hours post fertilization (hpf) was retarded based on global morphology score decreases after exposure to oil WAF-OM, WAF-OS and WAF-OR, with lowest effect concentrations (LOEC) of 2.2, 3.6 and 1.6 µg total PAHs L -1 , respectively. WAF-OM coast was a more potent inducer of developmental delays in zebrafish than unweathered WAFs from Oman and Merey crude oils in other studies. Decreases in heart rate on larvae exposed to WAF-OM and WAF-OS and high frequencies of heart deformities in larvae exposed to WAF-OM and WAF-OR were observed. WAF-OM was more potent to induce larval failure in swim bladder inflation with median effect concentration (EC50) of 1.62 µg total PAHs L -1 , and WAF-OM was also more potent to induce reduced swimming speeds of larvae (LOEC of 1.1 µg total PAHs L -1 ). The higher potency of WAF-OM to induce developmental delay, failure in swim bladder inflation and reduced swimming speeds was associated with higher concentrations of alkylated naphthalenes. LOECs for developmental delay, failure in yolk sac absorption, swim bladder inflation, and mouth development are within environmental PAH concentrations detected in field samples, and indicate that toxicity could be observed in the field.

MEMBROS DA BANCA:
Interno - 1732826 - GIOVANNI AMADEU PAIVA DOS SANTOS
Externa ao Programa - 1200149 - LILIA PEREIRA DE SOUZA SANTOS - nullInterna - 2581104 - MONICA LUCIA ADAM
Presidente - 1551332 - PAULO SERGIO MARTINS DE CARVALHO