The temperature increase due to climate warming can affect the photosynthetic responses of aquatic macrophytes from tropical lotic ecosystems

Author(s)

Carriel, Orlando Aparecido ; Diagonel, Guilherme ; Boas, Lucas Kortz Vilas ; de Oliveira, Regis Campos ; Branco, Ciro Cesar Zanini

• Document type: Journal article
• Source: Tropical Ecology; v. N/A, p. 8-pg., 2023-02-07.

Abstract

Over time, the average global temperature has varied greatly, mainly due to natural phenomena. However, several anthropic activities have caused significant changes in the Earth's atmosphere, so that various greenhouse 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 (e.g., macrophytes). Using photosynthetic parameters calculated from chlorophyll a fluorescence and measurements of chlorophyll a content, we assessed the potential effects of temperature increases predicted by two future scenarios from the fifth assessment report of the Intergovernmental Panel on Climate Change (IPCC), Representative Concentration Pathway 4.5 (RCP 4.5) and Representative Concentration Pathway 8.5 (RCP 8.5), on the photosynthetic responses of five aquatic macrophytes from tropical lotic ecosystems. Our results showed a trend of a reduction in the phi PSII values associated, as a rule, with an increase in the heat dissipation values in the reaction centers of photosystem II, that is, parameter E. Such reductions in the phi PSII associated with increases in parameter E suggest that most likely, even the less severe RCP scenario, RCP 4.5, is already sufficient to negatively and significantly affect the photosynthetic responses of most aquatic macrophytes tested in this experimental study. Considering that macrophytes, alongside macroalgae and periphyton, form the basis of autotrophic food webs in tropical lotic ecosystems, our results suggest that there is a real possibility that the negative effects produced by global warming on these primary producers are propagated, as a "cascade effect", indirectly affecting higher trophic levels as well. (AU)

• FAPESP's process: 14/22952-6 - Experimental ecological studies on stream macroalgae: effects of habitat complexity, hydraulic conditions and physical disturbances and the presence of herbicides on the establishment and development of these organisms
• Grantee: Ciro Cesar Zanini Branco
• Support Opportunities: Regular Research Grants