Global warming effects on the trophic structure and ecosystem functioning in tank-bromeliads

Abstract

Even though studies about the effect of climate change on biodiversity have increased over the past 10 years, few studies to date have investigated empirically the effect of global warming on the ecosystem and trophic structure of aquatic environments, especially in neotropical environments. In this study, will be investigated the effect of global warming (expected within the climate change scenario in Brazil for the next 100 years) combined with the effect of predator diversity on community structure (richness and composition of species and functional groups) and the aquatic ecosystem functions (productivity, decomposition and nutrient cycling) in fitotelmatas from tank-bromeliads. The heating system will consist of heaters and thermostats with temperature control systems and digital monitoring. The heating will be composed of three temperature levels: i) average projected for 2040 (increase to 2°C), ii ) 2100 (4°C increase) and iii ) control (current temperature). Predation possesses three levels combined orthogonally with heating treatments: 1) high diversity (three species of predators), 2) low diversity (only one species of predator) and 3) no predator (control). Thus, each block will consist of nine treatments randomly distributed, and the experiment consists of five blocks. This study will be conducted in the Restinga of the Serra do Mar State Park, Picinguaba, Ubatuba - SP. The main issues are: i) How the increase in temperature affects the structure and trophic composition of the community (e.g., abundance and biomass within functional trophic groups, predator-prey ratio)? ii) Does the temperature increase affect the productivity rate of decomposition of waste nitrogen stream and fitotelmatas? iii) Does the heating decreases the average size of aquatic organisms by altering the trophic structure (e.g., predator-prey ratio) and ecosystem responses? iv) Does the effect of temperature increases and the trophic ecosystem functioning structure are minimized in the presence of predators? v) Are the communities with greater diversity of top predators less affected by climate change? It is expected that, for example, the warming causes changes in trophic structure and aquatic ecosystem functions, primarily affecting organisms of higher trophic levels. Thus, there would be a change in the dynamics of trophic networks controlled by top-down relationships, increasing the detritivorous effect. However, in situations with higher diversity of predators may be a minor impact of warming and more prey removing. It is therefore likely that there is greater cascading effect decreasing rates of decomposition and nutrient cycling