BioChanger

The main objective of this proposal assess how changes in the general circulation of the Ria de Aveiro induce changes in hydrodynamic patterns and turn on the biogeochemistry of the lagoon, giving emphasis to the role of phytoplankton and microphytobenthos the main contributions of primary production. This project focus will be on how the tide level, changes in the frequency and intensity of meteorological origin superelevations, changes in river flow and changes in the mouth of the configuration of the Ria de Aveiro affect the hydrodynamics of the lagoon and consequently the amount of phytoplankton and the size of the intertidal areas, which will affect the distribution of microalgae, changing the primary productivity in the lagoon. Another aspect to consider is carbon fixation by phytoplankton (water column) and the microphytobenthic (intertidal zones). According to recent climate scenarios (IPCC, 2007), Southern Europe will become drier, increasing the frequency of heavy rainfall, which will increase the river flow of the rivers that flow into the estuary. Thus, erosion and charges of particulate material will increase, leading to a lowering of the light available for phytoplankton growth, affecting primary production. The rise of future sea level and changes in the mouth of the configuration of the Ria de Aveiro, produce changes in the general circulation of the lagoon, leading to changes in the dimensions of the intertidal zones, inducing changes in the patterns of stratification / mixing in the cycles of tide and the cycles hands-tide tide dead. These changes in the dimensions of the intertidal zones may also induce changes in current velocity within the lagoon, which will affect the distribution of organisms in the water column. The increase / decrease in intertidal zones affect the distribution of benthic microalgae and consequently the primary production. Currently, carbon sequestration in the intertidal zones of an estuary is a topic of great ecological importance. The intertidal areas are colonized by benthic microalgae, with carbon fixation rates in the range of 150 oC / m²ano (Serôdio and Catarino, 2000). These benthic communities are responsible for over 50% of the carbon retained by the ecosystem (Kromkamp and Underwood, 1999). This carbon fixed by microphytobenthic can be resuspended into the water column, or consumed by other organisms can migrate to the deeper layers of sediment (Middelburg et al., 2000). Thus, this proposal aims to answer the following questions: - What is the impact on the hydrodynamics of the Ria de Aveiro of future climate change and human pressures as the expansion of the port of Aveiro or dredging)? - How do these changes affect the entry of fine sediments and nutrients in the lagoon, the exchanges with the ocean and the dimensions of the intertidal areas, and thus of primary production in the lagoon? - As the primary productivity is due to the distribution of phytoplankton (water column) and microphytobenthic (sediment layer)? - What is the role of the water column and intertidal areas as carbon sinks? In order to answer these questions, this proposal follows a strong numerical component, which uses a hydrodynamic and biogeochemical model (MOHID, Leitão et al., 2005 http://www.mohid.com). Under the project, one mdelo will be developed to simulate the distribution of microphytobenthic, using a methodology similar to that followed by Matthew (2006) to capture pelagic processes. The use of numerical model will be complemented by a strong field component, whose data will be used to validate the numerical models and to better understand and characterize estuarine processes. Field data include physical variables and planktonic biomass and microphytobenthic. Primary production rates will be determined on-site by taking advantage of chlorophyll fluorescence indices for the estimation of carbon sequestration rates for phytoplankton (Kromkamp et al., 2008) and for microphytobenthic (Serôdio et al. , 2007). The river discharges of major rivers will be monitored (INAG, http://www.snirh.pt), identifying the extreme conditions of flow. The project will adopt a multidisciplinary approach, integrating areas such as hydrology, hydrodynamics and estuarine biogeochemistry and numerical modeling, taking advantage of the research team's capabilities to achieve the proposed objectives.