Respostas fisiológicas e metabólicas do tambaqui (Colossoma macropomum, Cuvier 1818) às alterações climáticas previstas pelos diferentes cenários do IPCC para o ano de 2100

Abstract

Tambaqui (Colossoma macropomum) is a well adapted fish, since it survives natural environmental adversities of Amazon ambient. However, we still need to understand the possible effects of climate changes over this species. There is a straight relationship between temperature and this species distribution in it’s natural habitat. Several fish were acclimated in four distinct temperatures (25º, 28º, 31º e 34ºC) during 14 days, following by a linear increase or decrease in temperature, until reaching the sublethal temperatures. The temperature tolerance polygon was determined with a total area of 266,71ºC2. Results show that tambaqui has lower thermal plasticity in comparison with temperate species. The experiment’s related to 30 days exposure to IPCC climate change scenarios for 2100, resulted in hematological changes for tambaqui after 30 days. Hematocrit showed to be significantly different (p<0,05) after 30 days, suggesting that the exposure to the different scenarios caused stress in these fish. Muscle LDH activity showed to be significantly different (p<0,05) after 30 days of exposure to light, medium and extreme scenarios, in comparison to initial time. LDH ratio indicates inhibition of LDH in muscle and heart tissue. LDH kinetic results in heart muscle LDH resulted in no significant differences during the experiment, reassuring its thermostability. On the other hand, the Km of skeletal muscle LDH showed, for animals exposed after 30 days to the scenarios, to be variable (p<0,05). The present study concludes that high temperatures with high CO2 concentrations induce metabolic stress on tambaqui.