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- EcoDynamo - Ecological Dynamics Model ApplicationPublication . Pereira, António; Duarte, Pedro
- ECODOURO - Modelling the effect of freshwater reduction and pulse discharge on the water dynamics and processes of the Crestuma ReservoirPublication . Bordalo, Adriano; Duarte, Pedro; Wiebe, WilliamThis report deals with the activities carried out during the project 72 months, from March 15, 2003 to September 15, 2006 under the framework of the ECODOURO - Modelling the effect of freshwater reduction and pulse discharge on the water dynamics and processes of the Crestuma Reservoir (POCTI/MGS/45533/2002). The report includes the fieldwork, data interpretation and mathematical modeling according to the seven working packages presented in the original proposal. Data is available to the public at http://ecodouro.icbas.up.pt. The main objectives of this goal oriented research project implemented on the Crestuma Reservoir (Douro River) are: i. To evaluate the long-term effects of flow reduction on key environmental variables and processes that occur in the Crestuma Reservoir; and ii. To evaluate the effect of high frequency oscillations (freshwater pulse discharges) on the ecosystem dynamics in terms of water column stratification, water temperature and turbidity, oxygen, nutrient availability, phytoplankton biomass and primary productivity. The original requested budget was reduced by 19%, and the evaluation commission recommended the non-acquisition of a second multiprobe CTD. Thus, the entire field survey program was changed accordingly. The seasonal sampling was conducted at two anchor stations located about 500 m and 2,500 m from the Crestuma dam crest. Surveys were performed on December 2003 (Fall), February 2004 (Winter), May 2004 (Spring) and August 2004 (Summer). An un-scheduled survey was carried out at the onset of the program (May 2003), in order to gather basic data since no departure data (short term series) were available contrarily to what was though. This approach proved to be very useful and the obtained results were applied in the following surveys. Moreover, since no workable bathymetrics were available to the research team (only depth contours in chart format restricted to the navigational channel) several dedicated surveys were organized in order to generate bottom contour maps for the last 10 km of the reservoir, covering the two-field stations location. As a result, a costume-made GIS was created and data used to run the model. All technical details of both the employed models (2D-vertically resolved model and the coupled biogeochemical model), including the complete mathematical formulae, are 2 presented in Annexes I and II. The rationale for selection of the modeled parameters are presented; the field data obtained from the 4+1 surveys were used to initialize the models. It was found that the different flow time-scales might influence water dynamics, biogeochemistry and primary productivity. For example, during the day, longitudinal flows results from upstream forcing, with river water entering into the reservoir. A clear longitudinal flow profile emergeed, disturbed in some points by depth changes that forces upwelling of bottom water. During the night, in the absence of river flow, at it happens frequently in Spring through Fall, convective flow dominated, with surface cooled water sinking to the bottom and forcing the ascent of bottom water. Vertical flows may be larger than horizontal ones. On the other hand, the highest phytoplankton production was observed in May and September, when microalgae were using more efficiently the available light. Furthermore, phytoplankton efficiency decreased from morning to dawn. Considering the objectives of this project, several model simulations were carried out to analyze the effects of flow variability on water column stratification and quality (cf. – Annexe III). These simulations were carried out with the same average flow magnitude and forcing conditions, in terms of water temperature, nutrients and chlorophyll concentrations, but different flow frequencies and amplitudes. Results obtained suggest that flow variability may not have a large effect on water temperature, nutrient and chlorophyll concentration and net primary production at annual time scales. However, when the time scale under analysis is reduced to seasonal and monthly, effects of flow variability become apparent, especially during the summer period and when flow is hold constant. Constant flow implies that extreme low and high values do not occur. Under this situation of “extreme” flow regulation, it appears that the synergies between river forcing and reservoir processes tend to reduce phytoplankton biomass. Therefore, from a management point of view, it is apparent that stabilizing the flow may prevent the development of phytoplankton blooms. On the other hand, results presented and discussed in Annex IV suggest that the Crestuma reservoir has undergone some important changes over the period 1999-2005, with significant increases in nitrogen and phosphorus and a decrease in the nitrogen: phosphorus ratio i.e. the Redfield ratio. One possible change, arising from the shifts in the nitrogen: phosphorus ratio, is the apparent autumn shift towards nitrate-nitrogen limitation of phytoplankton. Apart from increasing nutrient runoff within the watershed, the 3 noticeable nutrient increase trend found in the Crestuma resevoir may also be explained by the reduction of chlorophyll as a result of the massive development of the invasive clam Corbicula sp. Thus, the Crestuma reservoir is now a predominantly heterotrophic ecosystem that is the source of water to 20% of the Portuguese population and feeds the Douro estuary with most of the water that reaches the Atlantic Ocean. As a result of this project, a full functional calibrated with dedicated data model is available. During the 72 mo of the project, three young researchers were able to work and get training in the different areas covered by the program. Due to the enormous amount of data gathered, only two research papers were published. Thus, in the near future, two papers will be submitted (as a result of Annex III and Annex IV), and two additional papers are under preparation. Part of the obtained data has being used for teaching purposes at undergraduate and Master/PhD levels by the PI and the Cemas team.
- DSS Application (Ria Formosa Lagoon)Publication . Pereira, António; Duarte, PedroThis report presents the Decision Support System (DSS) applied to the Ria Formosa lagoon using an agent-based simulation approach. The idea is to include the interests of the decision-makers and stakeholders in the ecological system simulation; these entities are modelled as intelligent agents that communicate with the simulation tool (EcoDynamo) building one multi-agent community system. The intelligent agents, each one with some goals about the simulation results of the simulated system, have perception of their environment, reason, using their knowledge and are able to change the simulated environment by using a given set of configurable actions. Two intelligent agents are being developed at the moment: one calibration agent and one aquaculture/farming agent. The former intends to optimise the fit between observed and simulated results, and the latter looks for production optimisation. The agent used to generate this report is a development tool that includes actions from both agents. This report also introduces ECOLANG, a communication language developed during the DITTY project, with the main purpose of interchanging information between the simulation application of aquatic ecosystems - EcoDynamo - and external agents. Finally, the report focuses on the integration of the Analytical Hierarchy Process (AHP), developed by the University of Siena, in the aquaculture/farming agent decision process (Siena 2005 and Siena 2006)
- Fecundity, spore recruitment and size in Gelidium sesquipedale (Gelidiales,Rhodophyta)Publication . Santos, R.; Duarte, PedroGelidium sesquipedale fecundity was quantified by counting tetrasporangial sori and cystocarps per meter squared and by estimating the number of spores contained inside them . These were obtained by regression on a size metric of reproductive structures . Tetrasporangial sori length and cystocarp thickness were the best estimators of spore number. To assess spore recruitment, 12 pottery tiles were fixed to the bottom, and the appearance of small fronds was monitored. No clear seasonal pattern of reproduction was found . Tetraspore production peaked in March 1990 with 10.4 x 106 spores m-2, whereas the carpospore peak was lower, 4.9 x 10 5 spores m-2 in July 1989. Recruitment followed tetraspore peaks . The probability of a G. sesquipedale tetraspore making the transition to a recruit was 4.7 x 10-5. Frond length was significantly related to tetrasporangial sori number, while cystocarp number was only related to frond branching order. Minimum size for reproduction was 6.9 cm for gametophytes and 5.4 cm for tetrasporophytes; very rarely were cystocarpic fronds smaller than 9 cm, while tetrasporic fronds were often longer than 15 cm . Cystocarpic fronds were significantly shorter and had more branches than tetrasporic fronds .
- Impact of Oporto Metropolitan Area carbon dioxide emissions over the adjacent coastal zonePublication . Carvalho, Rogério; Barros, Nelson; Duarte, PedroConcerns about global warming over the last years have stimulated a large number of studies regarding atmospheric and oceanic carbon dioxide (CO2) concentration and its consequences. In spite of the available data on global atmospheric CO2, there is only limited knowledge on CO2 variability at regional scales. Moreover, there is an important gap in our understanding of the contribution of high CO2 emission regions, such as metropolitan areas, to CO2 concentrations over nearby coastal areas–considered by several authors as an important CO2 sink. A possible working hypothesis is that, large littoral metropolitan areas may have a significant influence on CO2 atmospheric concentrations over those areas and exert an important influence on sea-air CO2 exchanges. Therefore, the main objective of this study is to estimate CO2 concentration at a regional scale, under the influence of Oporto Metropolitan Area (OMA) emissions as a first test of this hypothesis. To fulfil this objective, an emission database was built and used to force, together with meteorological synoptic data, a mesoscale atmospheric dispersion model. The model was used to simulate several weather scenarios and estimate CO2 concentrations along a ca. 90 km stretch of the Portuguese northern shore. The results obtained suggest that emissions from OMA have an important influence on CO2 atmospheric concentrations up to 6–12 km offshore, particularly in autumn and winter. However, this CO2 increase does not seem to have the potential to significantly affect sea-air CO2 exchanges, although this is just a preliminary conclusion that has to be tested by field work.
- The relationship between phytoplankton diversity and community function in a coastal lagoonPublication . Duarte, Pedro; Macedo, M.F.; Cancela da Fonseca, LuísThe decrease of biodiversity related to the phenomena of global climate change is stimulating the scientific community towards a better understanding of the relationships between biodiversity and ecosystem functioning. In ecosystems where marked biodiversity changes occur at seasonal time scales, it is easier to relate them with ecosystem functioning. The objective of this work is to analyse the relationship between phytoplankton diversity and primary production in St. André coastal lagoon – SW Portugal. This lagoon is artificially opened to the sea every year in early spring, exhibiting a shift from a marine dominated to a low salinity ecosystem in winter. Data on salinity, temperature, nutrients, phytoplankton species composition, chlorophyll a (Chl a) concentration and primary production were analysed over a year. Modelling studies based on production-irradiance curves were also conducted. A total of 19 taxa were identified among diatoms, dinoflagellates and euglenophyceans, the less abundant group. Lowest diversities (Shannon– Wiener index) were observed just before the opening to the sea. Results show a negative correlation (p<0.05) between diversity and chlorophyll a (Chl a) concentration (0.2–40.3 mg Chl a m-3). Higher Chl a values corresponded to periods when the community was dominated by the dinoflagellate Prorocentrum minimum (>90% of cell abundance) and production was maximal (up to 234.8 mg C m-3 h-1). Maximal photosynthetic rates (Pmax) (2.0–22.5 mg C mg Chl a-1 h-1) were higher under lower Chl a concentrations. The results of this work suggest that decreases in diversity are associated with increases in biomass and production, whereas increases correspond to opposite trends. It is suggested that these trends, contrary to those observed in terrestrial and in some benthic ecosystems, may be a result of low habitat diversity in the water column and resulting competitive pressure. The occurrence of the highest photosynthetic rates when Chl a is low, under some of the highest diversities, suggests a more efficient use of irradiance under low biomass–high diversity conditions. Results suggest that this increased efficiency is not explained by potential reductions in nutrient limitation and intraspecific competition under lower biomasses and may be a result of niche complementarity.
- Scenario Analysis in Ria Formosa with EcoDynamoPublication . Duarte, Pedro; Azevedo, Bruno; Ribeiro, Catarina; Pereira, António; Falcão, Manuela; Serpa, Dalila; Bandeira, Rui; Reia, JoãoRia Formosa is a natural park managed partly by the Portuguese end-users of the DITTY project – Ria Formosa Natural Park authority, under “Instituto para a Conservação da Natureza (ICN)”. There are many conflicting interests over the management of this important coastal area: fishing, tourism, aquaculture, salt production, harbour activities, urban development and conservation. Furthermore, several institutions, such as the Natural Park Authority, municipalities, the Portuguese Navy, just to mention a few, are involved in decision-making over several areas of the natural park. Within DITTY, several scenarios were selected among those relevant for the management of this coastal ecosystem, considering available information from the end-users, relative importance of the mentioned scenarios, modelling and time constraints.
- Avaliação da capacidade de carga para o cultivo de bivalves filtradoresPublication . Baltazar, João; Lamas, José; Vale, Nuno; Bandeira, Rui; Duarte, PedroA aquicultura de bivalves é uma actividade com uma grande importância económica em diversas regiões, pelo que deve ser dimensionada de modo correcto, para garantir a sua sustentabilidade. Nesse sentido, a determinação da capacidade de carga (CC ) dos ecossistemas costeiros para o cultivo de bivalves é um tema importante. A CC determina-se, geralmente, com recurso a modelos matemáticos. O objectivo deste trabalho é avaliar empiricamente a importância da resolução espacial desses modelos na determinação da CC . Os resultados obtidos põem em causa o desempenho de modelos com uma resolução espacial reduzida, tendentes a estimar por excesso a CC .
- Análise e verificação de um modelo ecológico para a albufeira de Crestuma-LeverPublication . Azevedo, Bruno; Duarte, Pedro; Bordalo, Adriano A.A Directiva Quadro da Água coloca uma série de desafi os novos à gestão dos recursos hídricos. Estes desafios poderão implicar a utilização de modelos matemáticos que permitam antecipar os efeitos das acções antropogénicas sobre as águas superfi ciais. Este trabalho tem como principal objectivo apresentar um modelo ecológico da barragem de Crestuma-Lever e os resultados dos primeiros testes efectuados com o mesmo. O modelo foi desenvolvido no âmbito de um dos projectos em que participa o CIIMAR e a Universidade Fernando Pessoa e espera-se que possa vir a ser utilizado como uma ferramenta útil na gestão da barragem de Crestuma-Lever.
- A model for the simulation of macroalgal population dynamics and productivityPublication . Duarte, Pedro; Ferreira, JoãoA mathematical model to simulate the population dynamics and productivity of macroalgae is described. The model calculates the biomass variation of a population divided into size-classes. Biomass variation in each class is estimated from the mass balance of carbon fixation, carbon release and demographic processes such as mortality and frond breakage. The transitions between the different classes are calculated in biomass and density units as a function of algal growth. Growth is computed from biomass variations using an allometric relationship between weight and length. Gross and net primary productivity is calculated from biomass production and losses over the period of simulation. The model allows the simulation of different harvesting strategies of commercially important species. The cutting size and harvesting period may be changed in order to optimise the calculated yields. The model was used with the agarophyte Gelidium sesquipedale (Clem.) Born. et Thur. This species was chosen because of its economic importance as a the main raw material for the agar industry. Net primary productivity calculated with it and from biomass variations over a yearly period, gave similar results. The results obtained suggest that biomass dynamics and productivity are more sensitive to the light extinction coefficient than to the initial biomass conditions for the model. Model results also suggest that biomass losses due to respiration and exudation are comparable to those resulting from mortality and frond breakage. During winter, a significant part of the simulated population has a negative net productivity. The importance of considering different parameters in the productivity light relationships in order to account for their seasonal variability is demonstrated with the model results. The model was implemented following an object oriented programming approach. The programming methodology allows a fast adaptation of the model to other species without major software development.