Efeitos dos metais na fisiologia de crustáceos e moluscos de interesse econômico
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Data
2022-12-14
Autores
Costa, Juliana Rodrigues
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Universidade Estadual Paulista (Unesp)
Resumo
O cádmio (Cd) é um metal não essencial para os organismos. Ele está presente em baterias e pilhas recarregáveis e o seu descarte inadequado tem aumentado a concentração deste poluente nos ambientes costeiros. Embora os metais possam alterar a homeostase dos animais e causar uma redistribuição da energia que seria canalizada para as diferentes funções fisiológicas, pouco se sabe sobre o balanço energético de espécies expostas à poluentes. Portanto, nosso objetivo foi avaliar os efeitos do cádmio na fisiologia de Litopenaeus vannamei, o camarão marinho mais cultivado no mundo. Os animais foram expostos durante 30 dias à água contendo 0,1mg/L de cádmio; os animais controles foram mantidos em água sem adição de cádmio. Foi escolhida uma concentração de cádmio que realmente ocorre em águas poluídas na natureza. Quantificamos a energia ingerida diariamente e canalizada para crescimento e metabolismo ou perdida na excreção nitrogenada, exúvia e fezes. Também foi avaliado o tipo de substrato energético oxidado pelos animais, o índice hepatossomático e a osmolalidade da hemolinfa. O metabolismo foi avaliado por meio do consumo de oxigênio de animais mantidos em câmaras respirométricas fechadas e a excreção de amônia por colorimetria. Os conteúdos energéticos foram detectados em bomba adiabática. Os efeitos do metal foram avaliados pelo teste T seguido pelo SNK. Houve mortalidade (30%) apenas em L. vannamei exposto ao cádmio. Animais expostos ao cádmio canalizaram mais energia para o crescimento (33% da energia ingerida) do que os animais controles (20%). A maior parte da energia ingerida foi canalizada para o metabolismo (cerca de 40%) em ambos os tratamentos. Cerca de 30% da energia ingerida foi canalizada para as demais funções como defecação, excreção nitrogenada e muda. O tipo de substrato energético oxidado (uma mistura de proteínas e lipídeos), índice hepatossomático (cerca de 6,6) e osmolalidade da hemolinfa (cerca de 705 mOsm/Kg água) não sofreram alterações em função da exposição ao metal. Concluímos que a exposição crônica a cádmio causa hormese e altera aspectos da fisiologia de L. vannamei, inclusive o balanço energético. Nesta espécie a hormese está relacionada ao rápido crescimento, uma resposta adaptativa visto que animais maiores podem ser mais eficientes na evitação da predação e as fêmeas podem acomodar um maior número de ovos em seus pleópodos. No entanto, o crescimento dos artrópodes é dependente da troca do exoesqueleto e os animais apresentaram uma alta taxa de mortalidade na pós muda. Além disso, não se sabe se os animais que tiveram uma elevada taxa de crescimento durante os 30 dias de exposição ao cádmio sofrerão efeitos a longo prazo decorrentes de tal exposição. Visto que os animais foram expostos a uma concentração de cádmio que realmente é encontrada no meio ambiente, o presente trabalho mostra que este é um metal que pode afetar biologia da espécie e a aquicultura deste importante camarão marinho.
Cadmium (Cd) is a non-essential metal for organisms. he is present in batteries and rechargeable batteries and their inappropriate disposal has increased the concentration of this pollutant in coastal environments. although the metals may alter the homeostasis of the animals and cause a redistribution of energy that would be channeled to the different physiological functions, little is know about the energy balance of species exposed to pollutants. Therefore, our objective was to evaluate the effects of cadmium on the physiology of Litopenaeus vannamei, the most cultivated marine shrimp in the world. The animals were exposed for 30 days to water containing 0.1mg/L of cadmium; the animals controls were kept in water without addition of cadmium. one was chosen concentration of cadmium that actually occurs in polluted waters in nature. We quantify the energy ingested daily and channeled towards growth and metabolism or lost in nitrogen excretion, exuvia and feces. It was also evaluated the type of energetic substrate oxidized by the animals, the hepatosomatic and hemolymph osmolality. Metabolism was assessed by through the oxygen consumption of animals kept in respirometric chambers closed and ammonia excretion by colorimetry. The energetic contents were detected in adiabatic pump. The effects of the metal were evaluated by the T test followed by the SNK. There was mortality (30%) only in L. vannamei exposed to cadmium. Animals exposed to cadmium channeled more energy for growth (33% of energy intake) than animals controls (20%). Most of the ingested energy was channeled to the metabolism (about 40%) in both treatments. About 30% of ingested energy was channeled to other functions such as defecation, nitrogenous excretion and moulting. The type of oxidized energy substrate (a mixture of proteins and lipids), hepatosomatic index (about 6.6) and hemolymph osmolality (about 705 mOsm/Kg water) did not suffer changes due to exposure to the metal. We conclude that the exposure chronic cadmium causes hormesis and alters aspects of the physiology of L. vannamei, including energy balance. In this species, hormesis is related to the rapid growth, an adaptive response as larger animals can be more efficient in avoiding predation and females can accommodate a greater number of eggs in their pleopods. However, the growth of arthropods is dependent on exoskeleton exchange and the animals showed a high post-molt mortality rate. Furthermore, it is not known whether the animals that had a high growth rate during the 30 days of exposure to cadmium will suffer long-term effects from such exhibition. Since the animals were exposed to a concentration of cadmium that is actually found in the environment, the present work shows that this is a metal that can affect the biology of the species and the aquaculture of this important marine shrimp.
Cadmium (Cd) is a non-essential metal for organisms. he is present in batteries and rechargeable batteries and their inappropriate disposal has increased the concentration of this pollutant in coastal environments. although the metals may alter the homeostasis of the animals and cause a redistribution of energy that would be channeled to the different physiological functions, little is know about the energy balance of species exposed to pollutants. Therefore, our objective was to evaluate the effects of cadmium on the physiology of Litopenaeus vannamei, the most cultivated marine shrimp in the world. The animals were exposed for 30 days to water containing 0.1mg/L of cadmium; the animals controls were kept in water without addition of cadmium. one was chosen concentration of cadmium that actually occurs in polluted waters in nature. We quantify the energy ingested daily and channeled towards growth and metabolism or lost in nitrogen excretion, exuvia and feces. It was also evaluated the type of energetic substrate oxidized by the animals, the hepatosomatic and hemolymph osmolality. Metabolism was assessed by through the oxygen consumption of animals kept in respirometric chambers closed and ammonia excretion by colorimetry. The energetic contents were detected in adiabatic pump. The effects of the metal were evaluated by the T test followed by the SNK. There was mortality (30%) only in L. vannamei exposed to cadmium. Animals exposed to cadmium channeled more energy for growth (33% of energy intake) than animals controls (20%). Most of the ingested energy was channeled to the metabolism (about 40%) in both treatments. About 30% of ingested energy was channeled to other functions such as defecation, nitrogenous excretion and moulting. The type of oxidized energy substrate (a mixture of proteins and lipids), hepatosomatic index (about 6.6) and hemolymph osmolality (about 705 mOsm/Kg water) did not suffer changes due to exposure to the metal. We conclude that the exposure chronic cadmium causes hormesis and alters aspects of the physiology of L. vannamei, including energy balance. In this species, hormesis is related to the rapid growth, an adaptive response as larger animals can be more efficient in avoiding predation and females can accommodate a greater number of eggs in their pleopods. However, the growth of arthropods is dependent on exoskeleton exchange and the animals showed a high post-molt mortality rate. Furthermore, it is not known whether the animals that had a high growth rate during the 30 days of exposure to cadmium will suffer long-term effects from such exhibition. Since the animals were exposed to a concentration of cadmium that is actually found in the environment, the present work shows that this is a metal that can affect the biology of the species and the aquaculture of this important marine shrimp.
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Fisiologia, Crustáceos, Moluscos, Ecotoxicologia