Respostas metabólicas e ionoregulatórias de organismos aquáticos da bacia do Rio Preto (Itanhaém/SP) ao aumento de temperatura
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2023-05-16
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Universidade Estadual Paulista (Unesp)
Resumo
O aumento de temperatura nos corpos d’água doce em decorrência de eventos climáticos pode ultrapassar o limite térmico de algumas espécies animais ectotérmicas, causando alterações metabólicas e ionorregulatórias, como nas taxas de consumo de oxigênio, excreção de nitrogênio e fluxo iônico, podendo levar os animais à morte. Além da temperatura alta, rios e riachos possuem diferentes características limnológicas, com ambientes de águas claras e pretas, que apresentam diferenças no pH e na concentração de carbono orgânico dissolvido (COD), o que também interfere no metabolismo animal. A cidade de Itanhaém tem uma rica hidrografia, com rios e riachos de águas pretas e claras, e uma fauna aquática endêmica distribuída em grande parte de seu território, como os camarões Macrobrachium potiuna e Macrobrachium acanthurus e os peixes Scleromystax macropterus, Scleromystax barbatus e Phalloceros reisi. Assim, este estudo avaliou os efeitos do aumento da temperatura da água de origem sobre as respostas metabólicas e ionoregulatórias dessas espécies, verificando a influência do tipo de água de riachos da bacia do Rio Preto (Itanhaém/SP) sobre essas respostas. O experimento foi realizado em laboratório, separadamente para cada espécie, sendo M. potiuna, S. macropterus e P. reisi em água preta e M. acanthurus, S. barbatus e P. reisi em água clara, utilizando três temperaturas de aclimatação, duas de ocorrência nas águas dos riachos (22 ºC e 26 ºC) e uma reproduzindo a situação de extremo climático do IPCC 2021 (SSP3-7,0) (30 ºC), às quais os animais foram submetidos de 4 a 7 dias. O consumo de oxigênio (metabolismo de rotina; MO2), a excreção de amônia (JAmm), o uso de proteínas e os fluxos líquidos de Na+ (JNaNet) e Cl- (JClNet) foram determinados para o tempo de exposição de 2 horas em cada condição experimental de temperatura. O MO2 de M. acanthurus e P reisi, o JAmm das espécies de camarão e de P. reisi, o uso de proteínas de M. acanthurus e S. barbatus e o JNaNet de S. macropterus apresentaram aumento, acompanhando o aumento da temperatura. As espécies de água clara M. acanthurus e P. reisi foram as mais responsivas para todos os parâmetros avaliados em função do aumento de temperatura, exceto JClNet, o qual não apresentou alterações significativas em nenhuma condição experimental. Esses resultados demonstram que os animais de água clara da bacia do Rio Preto são mais responsivos ao aumento de temperatura, se tornando mais suscetíveis às alterações de regimes térmicos causados por emergências climáticas.
The increase in temperature in freshwater bodies due to the climatic events may exceed the thermal limit of some ectothermic animal species, causing metabolic and ionoregulatory changes, such as in oxygen consumption rates, nitrogen excretion and ionic flux, which can lead to animals to death. In addition to the high temperature, rivers and streams have different limnological aspects, with clearwater and blackwater environments. These aspects causes differences in pH and dissolved organic carbon (DOC) concentration, and affects the metabolism of animals. Itanhaém city has a rich hydrography, with rivers and streams of clearwater and blackwater, and an endemic aquatic fauna distributed throughout much of its territory, such as the shrimps Macrobrachium potiuna and Macrobrachium acanthurus and the fishes Scleromystax macropterus, Scleromystax barbatus and Phalloceros reisi. This study aimed to evaluate the effects of increasing the locus water temperature on the metabolic and ionoregulatory responses of these species, verifying the influence of the type of water in the streams of the Rio Preto basin (Itanhaém/SP) on these responses. The experiment was realized in laboratory environment, separated for each species, with sampling and procedures occurring in blackwater for M. potiuna, S. macropterus e P. reisi and clearwater for M. acanthurus, S. barbatus e P. reisi, through three acclimation temperatures, two of them being regular for stream water (22 ºC and 26 ºC), and one related to an extreme climate scenario given by IPCC 2021 (SSP3-7,0) (30 ºC), to which the individuals were submitted between 4 to 7 days. After two hours of exposure, the oxygen consumption (routine metabolism; MO2), ammonia excretion (JAmm), protein use and net flux of Na+ (JNa Net) and Cl- (JCl Net) were measured for each experimental condition. The MO2 of M. Acanthurus and P reisi, the JAmm of shrimp species and P. reisi, the use of proteins of M. Acanthurus and S. barbatus and the JNa Net of S. macropterus increased along with the increases in temperature. The clearwater species M. acanthurus and P. reisi were more responsive, for all of the parameters evaluated, in higher temperatures, except for JCl Net, which did not manifest changes in any experimental condition. These results demonstrate that clearwater animals from the Rio Preto basin are more responsive to temperature increase, becoming more susceptible to thermal regimes changes caused by climatic emergencies.
The increase in temperature in freshwater bodies due to the climatic events may exceed the thermal limit of some ectothermic animal species, causing metabolic and ionoregulatory changes, such as in oxygen consumption rates, nitrogen excretion and ionic flux, which can lead to animals to death. In addition to the high temperature, rivers and streams have different limnological aspects, with clearwater and blackwater environments. These aspects causes differences in pH and dissolved organic carbon (DOC) concentration, and affects the metabolism of animals. Itanhaém city has a rich hydrography, with rivers and streams of clearwater and blackwater, and an endemic aquatic fauna distributed throughout much of its territory, such as the shrimps Macrobrachium potiuna and Macrobrachium acanthurus and the fishes Scleromystax macropterus, Scleromystax barbatus and Phalloceros reisi. This study aimed to evaluate the effects of increasing the locus water temperature on the metabolic and ionoregulatory responses of these species, verifying the influence of the type of water in the streams of the Rio Preto basin (Itanhaém/SP) on these responses. The experiment was realized in laboratory environment, separated for each species, with sampling and procedures occurring in blackwater for M. potiuna, S. macropterus e P. reisi and clearwater for M. acanthurus, S. barbatus e P. reisi, through three acclimation temperatures, two of them being regular for stream water (22 ºC and 26 ºC), and one related to an extreme climate scenario given by IPCC 2021 (SSP3-7,0) (30 ºC), to which the individuals were submitted between 4 to 7 days. After two hours of exposure, the oxygen consumption (routine metabolism; MO2), ammonia excretion (JAmm), protein use and net flux of Na+ (JNa Net) and Cl- (JCl Net) were measured for each experimental condition. The MO2 of M. Acanthurus and P reisi, the JAmm of shrimp species and P. reisi, the use of proteins of M. Acanthurus and S. barbatus and the JNa Net of S. macropterus increased along with the increases in temperature. The clearwater species M. acanthurus and P. reisi were more responsive, for all of the parameters evaluated, in higher temperatures, except for JCl Net, which did not manifest changes in any experimental condition. These results demonstrate that clearwater animals from the Rio Preto basin are more responsive to temperature increase, becoming more susceptible to thermal regimes changes caused by climatic emergencies.
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Palavras-chave
Ecossistemas costeiros, Mudanças climáticas, Temperatura, Animais aquáticos, Homeostase iônica, Metabolismo de rotina, Excreção de nitrogênio, COD