Efeito das variações de temperatura relacionadas às mudanças climáticas globais sobre as respostas fotossintéticas de macrófitas aquáticas de ecossistemas lóticos tropicais.
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Data
2018-03-05
Autores
Carriel, Orlando Aparecido
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Universidade Estadual Paulista (Unesp)
Resumo
Ao longo do tempo a temperatura média global teve grandes variações, devido principalmente à fenômenos naturais. Porém, a partir da revolução industrial diversas atividades antrópicas vêm causando uma significativa alteração na atmosfera terrestre, de modo que diversos gases, especialmente CO2, têm aumentado a sua concentração atmosférica e, como consequência, produzido elevação na temperatura do planeta. Essas mudanças climáticas, particularmente o aquecimento global, podem afetar os organismos de ambientes aquáticos continentais, incluindo os produtores primários (p.ex., macrófitas). Utilizando o método de evolução do oxigênio dissolvido (técnica dos frascos claros e escuros), a técnica da fluorescência da clorofila a e a técnica da concentração de clorofila a, avaliou-se o efeito do aumento de temperatura potencialmente produzido pelo aquecimento global, previsto em dois cenários futuros do Painel Intergovernamental de Mudanças Climáticas (IPCC), RCP 4.5 e RCP 8.5, sobre as respostas fotossintéticas de macrófitas aquáticas de ecossistemas lóticos tropicais. As temperaturas de controle foram determinadas, para as estações de inverno e verão, a partir da temperatura média de riachos da região onde as amostras de macrófitas foram coletadas e as temperaturas experimentais calculadas adicionando-se os aumentos previstos pelos cenários testados do IPCC. A resposta à simulação dos cenários do IPCC ocorreu de modo espécie-específico. Sendo que para a maioria das espécies investigadas não foram registrados efeitos negativos ou significativos sobre a fotossíntese, com algumas espécies demonstrando inclusive um aumento na produtividade primaria nos cenários experimentais do IPCC em relação ao controle.
Over time, the average global temperature had great variations, mainly due to natural phenomena. However, since the industrial revolution several anthropic activities have caused a significant change in the Earth's atmosphere, so that various gases, especially CO2, have increased their atmospheric concentration and, consequently, produced an increase in the planet's temperature. These climatic changes, particularly global warming, can affect organisms in continental aquatic environments, including primary producers (eg, macrophytes). Using the method of evolution of dissolved oxygen (light and dark jars technique), chlorophyll a fluorescence technique and chlorophyll a concentration technique, the effect of the temperature increase potentially produced by global warming, predicted in two scenarios future of the Intergovernmental Panel on Climate Change (IPCC), RCP 4.5 and RCP 8.5, on the photosynthetic responses of aquatic macrophytes from tropical lotic ecosystems. Control temperatures were determined for the winter and summer seasons from the average stream temperature of the region where the macrophyte samples were collected and the experimental temperatures calculated by adding the predicted increases in the IPCC tested scenarios. The response to the simulation of the IPCC scenarios occurred in a species-specific manner. For most of the species investigated, there were no negative or significant effects on photosynthesis, with some species even showing an increase in primary productivity in the experimental scenarios of the IPCC in relation to the control.
Over time, the average global temperature had great variations, mainly due to natural phenomena. However, since the industrial revolution several anthropic activities have caused a significant change in the Earth's atmosphere, so that various gases, especially CO2, have increased their atmospheric concentration and, consequently, produced an increase in the planet's temperature. These climatic changes, particularly global warming, can affect organisms in continental aquatic environments, including primary producers (eg, macrophytes). Using the method of evolution of dissolved oxygen (light and dark jars technique), chlorophyll a fluorescence technique and chlorophyll a concentration technique, the effect of the temperature increase potentially produced by global warming, predicted in two scenarios future of the Intergovernmental Panel on Climate Change (IPCC), RCP 4.5 and RCP 8.5, on the photosynthetic responses of aquatic macrophytes from tropical lotic ecosystems. Control temperatures were determined for the winter and summer seasons from the average stream temperature of the region where the macrophyte samples were collected and the experimental temperatures calculated by adding the predicted increases in the IPCC tested scenarios. The response to the simulation of the IPCC scenarios occurred in a species-specific manner. For most of the species investigated, there were no negative or significant effects on photosynthesis, with some species even showing an increase in primary productivity in the experimental scenarios of the IPCC in relation to the control.
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Palavras-chave
Mudanças climáticas, Temperatura, Fotossíntese, Macrófitas, Climate change, Temperature, Photosynthesis, Macrophytes