Maria Rita Passos

Biomonitoring of the genotoxic potential (micronucleus and erythrocyte nuclear abnormalities assay) of the Admiralty Bay water surrounding the Brazilian Antarctic Research Station “Comandante Ferraz,” King George Island

The micronucleus (Mn) and other kinds of erythrocyte nuclear abnormality (ENA) assays were used to assess the genotoxic potential of the seawater in front of the Brazilian Antarctic Research Station “Comandante Ferraz” (King George Island). In two consecutive summers, the fish Trematomus newnesi was exposed to the seawater in front of the fuel storage tanks and the sewage discharge outlet of the Station in laboratory bioassays and in situ caging assays. After the exposure, frequencies of ENA and Mn were scored on blood smears. Significantly higher Mn and ENA frequencies in relation to those of the controls were observed in fish exposed to both types of water, in both types of experiment. Seawater in front of the fuel tanks and sewage discharge outlet at the Station was found to induce the formation of micronuclei and other ENAs, indicators of genotoxicity. The need for further investigation and the suitability of the methods for screening mutagenic pollution in polar waters are discussed.

Photo-induced toxicity of anthracene in the Antarctic shallow water amphipod, Gondogeneia antarctica

The photo-induced toxicity of anthracene was investigated as the mortality in Antarctic shallow water amphipod, Gondogeneia antarctica, at different concentrations of anthracene and different periods of exposure to natural sunlight and artificial UVA and UVB radiations. When exposed to natural sunlight, animals contaminated in the dark and placed in clean water or in anthracene solutions showed different degrees of mortality, dose–time dependent. Effects were even more evident when these animals were exposed to artificial UVA or UVB radiations. Depuration seemed to be a slow process. The effects of UV radiation and anthracene alone and the effects of the interactions of these two stressors implied that solar radiation is an important parameter that deserves consideration in the environmental assessment of polycyclic aromatic hydrocarbons in Antarctic coastal waters. G. antarctica proved to be a good bioindicator for the phototoxicity of anthracene in Antarctic shallow waters.

Effect of body size, temperature and starvation on oxygen consumption of antarctic krill Euphausia superba

O consumo de oxigenio de rotina de krll foi avaliado como uma forma de mensurar seu metabolismo e determinar os efeitos do tamanho, da temperatura e do jejum sobre o mesmo. Nao foram detectadas diferencas significativas no consumo total do animal apos 1, 3, 5 e 7 dias de jejum. As respostas do metabolismo de krill em funcao da variacao da temperatura demonstraram a existencia de uma faixa de independencia, de O°Ca 1°C, na qual a temperatura nao exerce nenhum efeito sobre o metabolismo. De 1°C a 4°C o metabolismo aumenta rapidamente em funcao da temperatura. Houve um aumento significativo no consumo de oxigenio em funcao do peso. A equacao que relaciona o consumo com o peso umido e dada pela formula Log Qoz = 2,061 + 0,987x LogW, com r=0,86. A declividade da regressao foi menor que a unidade (b= 0.987), indicando que o consumo de oxigenio por unidade de peso e maior em animais menores. A media da taxa metabolica de 164 krill a O°Ce 733,24 J- µlO2g (peso seco)-1 h-1. A taxa metabolica e de 1129,67 J- µlO2g (peso seco)-1 h-1 para animais pequenos (13 a 19 mg de peso seco) e 636,16 J- µlO2g (peso seco)-1 h-1 para animais maiores (160 a 169 mg de peso seco). Demonstrou-se que o metabolismo do krill esta relacionado ao periodo de adaptacao e ao tipo de respirometro. Periodos prolongados de adaptacao ocasionaram efeitos adversos sobre o metabolismo. A media do consumo de oxigenio foi cerca de 3 vezes mais elevada em respirometros com agitador do que em câmaras seladas simples.