Caring about the future

BioChangeR: Biogeochemical Processes induced by Climate and Anthropogenic Circulation Changes - The Case Study of Ria de Aveiro (Portugal)
Coordinator - Nuno Alexandre Firmino Vaz
Programme - PTDC/AAC-AMB/121191/2010
Execution dates - 2012-05-01 - 2015-09-30 (41 Months)
Funding Entity - Fundação para a Ciência e a Tecnologia
Funding for CESAM - 108103 €
Total Funding - 130967 €
Proponent Institution - Universidade de Aveiro
Participating Institutions
Instituto Superior Técnico (IST)/ Marine Environment and Technology Center (MARETEC)

Project Description

The main goal of this proposal is the integrated study of an estuarine system (Ria de Aveiro, Portugal) in terms of its hydro-biogeochemical evolution induced by anthropogenic and climate changes, with special emphasis on the role of phytoplankton and microphytobenthos as the main contributors to ecosystem-level primary production. The project will focus on how climate change factors (sea level rise, the change in storm surge occurrence and amplitude, and changes in the freshwater inflow) and anthropogenic factors (the ongoing changes in the configuration of the Ria de Aveiro inlet (including the extension of the northern jetty and dredging of the inlet channel)), will affect the lagoon circulation. In response, changes in the available amount of phytoplankton and in the dimensions of the intertidal areas will be induced, which, consequently, will affect the distribution of benthic microalgae, altering the global ecosystem-level primary productivity. The important arrest of carbon performed by phytoplankton and benthic microalgae communities at the intertidal areas of Ria de Aveiro will also be accessed for all the scenarios under research. According to recent climate change scenarios (IPCC, 2007), southern Europe will become dryer despite the increase in the frequency of the winter torrential rain events, that will rise the freshwater discharge into estuarine regions. Erosion processes and material loads are expected to increase, leading to an aggravation of light-limiting conditions to phytoplankton growth and consequently to primary production. Sea level rise, more frequent storm surge events and ongoing changes in the Ria de Aveiro inlet configuration will affect the lagoon circulation, leading to changes in tidal circulation and in present stratification/mixing patterns during ebb-flood, spring-neap and longer time scales. Changes in dry/wet areas will induce variations of the current patterns, ultimately it will also produce changes in the distribution of biological organisms in the pelagic layer. Moreover, changes in the intertidal areas dimensions are expected, affecting microphytobenthos distribution and, consequently, primary production. Presently, the arrest of carbon by the intertidal areas of an estuary is a research issue of great ecological relevancy. Estuaries are important carbon sources/sinks for the coastal ocean, affecting the coastal food webs and changing the global carbon budgets. Intertidal areas are colonized by benthic microalgae communities capable of carbon rates fixation of the order of 150 gC/m²year (Serôdio and Catarino, 2000). These microphytobenthos may be responsible by more than 50% of the carbon retained by the ecosystem (Kromkamp and Underwood, 1999). This retained carbon may be resuspended into the water column, consumed by other organisms, or it can be buried in deeper layers of the bottom sediment (Middelburg et al., 2000). The project is designed to answer the following questions: - What will be the impact in the Ria de Aveiro hydrodynamics of the foreseen climate changes and anthropogenic pressures (ongoing harbor expansion) scenarios? - How do these changes affect loads of fine sediments and nutrients, ocean-lagoon exchange and intertidal areas dimensions and consequently primary production distribution inside the lagoon? - How much of the primary production is due to phytoplankton (pelagic layer) and to microphytobenthos (benthic layer) distribution? - What is the role of the pelagic layer and intertidal areas as micro-algal carbon sink? The current proposal follows a strong numerical approach using state-of-the-art numerical hydro and biogeochemical marine models (Mohid, Leitão et al., 2005, A model to simulate microphytobenthos will be developed in the frame of this proposal following the approach recently developed by Mateus (2006). The numerical modelling methodology will be complemented by in-situ data collection and by analysis of available and collected data that will be used to validate the numerical models and to understand and characterize the estuarine processes. Field data will cover basic physical variables, phytoplankton and microphytobenthos biomass and primary productivity. Primary productivity rates will be determined in situ, taking advantage of recent developments on the use of in vivo chlorophyll fluorescence indices for the instantaneous and non-destructive estimation of carbon fixation rates, both for phytoplankton (Kromkamp et al. 2008) as well as for microphytobenthos (Serôdio et al. 2007). The project will adopt a multidisciplinary perspective by integrating methodologies of hydrology, estuarine hydrodynamics and biogeochemistry, and numerical modeling, taking advantage of the integrated approach and multiple expertise of the research team to achieve the proposed goals.

CESAM members on this project
João Miguel Dias

Research fellow
João Serôdio

Research fellow
Research Fellow
Silja Frankenbach

CESAM Funding: UIDP/50017/2020 + UIDB/50017/2020 + LA/P/0094/2020


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