Browsing by Author "Ferreira, J."
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- Analysis of coastal and offshore aquaculture: application of the FARM model to multiple systems and shellfish speciesPublication . Ferreira, J.; Sequeira, A.; Hawkins, A.; Newton, Alice; Nickell, T.; Pastres, R.; Forte, J.; Bodoy, A.; Bricker, S.The Farm Aquaculture Resource Management (FARM) model has been applied to several shellfish species and aquaculture types. The performance of the FARM model, developed to simulate potential harvest, key financial data, and water quality impacts at the farm-scale, was tested in five systems in the European Union: Loch Creran, Scotland (Pacific oyster), Pertuis Breton, France (blue mussel), Bay of Piran, Slovenia (Mediterranean mussel), Chioggia, Italy (Mediterranean mussel) and Ria Formosa, Portugal (Manila clam). These systems range from open coasts to estuaries, and are used for shellfish aquaculture by means of different cultivation techniques (e.g. oyster bottom culture in Loch Creran and mussel longlines and poles in Pertuis Breton). The drivers for the FARM model were supplied by measured data, outputs of system-scale models or a combination of both. The results (given in total fresh weight) generally show good agreement with reported annual production (shown in brackets) at each farm: simulated production of 134 tons of Pacific oyster in Loch Creran (150 tons, −10%), 2691 tons of blue mussel in Pertuis Breton (2304 tons, +17%), 314 tons of Mediterranean mussel in the Bay of Piran (200 tons, +57%), 545 tons of Mediterranean mussel in Chioggia (660 tons, −17%) and 119 tons of Manila clam in Ria Formosa (104 tons, +15%). The nitrogen mass balance for each farm was also determined with the FARM model. The net removal of nitrogen (N) by the farms was estimated to correspond to 1206 population equivalents per year (PEQ y−1) in Loch Creran, 93503 PEQ y−1 in Pertuis Breton, 9196 PEQ y−1 in the Bay of Piran, 97916 PEQ y−1 in Chioggia and 8613 PEQ y−1 in Ria Formosa. The aggregate income due to both the shellfish sale and substitution value of landbased fertilizer reduction or nutrient treatmentwas estimated to be about 700 k€ y−1 in Loch Creran, 30,706 k€ y−1 in Pertuis Breton, 3000 k€ y−1 in the Bay of Piran, 30,000 k€ y−1 in Chioggia, and 5000 k€ y−1in Ria Formosa. Outputs of FARM may be used to analyse the farm production potential and profit maximization according to seeding densities and/or spatial distribution. Results of a marginal analysis for all the study sites were determined. As an example, profit maximization in Loch Creranwas obtained with 97 tons of seed, resulting in a total production of 440 tons (profit of 2100 k€ for a culture period of about 2 years). FARM additionally integrates the well-known ASSETS model, for assessment of farm-related eutrophication impacts. The assessment results for the five study sites show that water quality is either maintained or improved in all farms under standard conditions of culture practice. FARM results may be used by farmers to analyse farm production potential and by managers for environmental assessment of farm-relatedwater quality impacts,whether positive or negative. It is a useful tool for all stakeholders for the valuation of nitrogen credits, which may be traded as part of an integrated catchment management plan. The FARM results were scaled up to determine a net value of 11–17 billion € y−1 of ecosystem goods and services, provided by shellfish culture towards reducing eutrophication in the coastal waters of the European Union. These numbers highlight the role that extractive organic aquaculture plays in integrated coastal zone and nutrient emissions management.
- Eutrophication and some European waters of restricted exchangePublication . Teet, Paul; Gilpin, Linda; Erlandsson, Carina; Larsson, Ulf; Kratzer, Susanne; Fouillandf, Eric; Janzen, Carol; Lee, Jae-Young; Grenz, Christian; Newton, Alice; Ferreira, J.; Fernandes, Teresa; Serge, ScoryRegions of Restricted Exchange (RREs) are an important feature of the European coastline. They are historically preferred sites for human settlement and aquaculture and their ecosystems, and consequent human use, may be at risk from eutrophication. The OAERRE project (EVK3-CT1999-0002 concerns ‘Oceanographic Applications to Eutrophication in Regions of Restricted Exchange’. It began in July 2000, and studies six sites. Four of these sites are fjords: Kongsfjorden (west coast of Spitzbergen); Gullmaren (Skagerrak coast of Sweden); Himmerfj.arden (Baltic coast of Sweden); and the Firth of Clyde (west coast of Scotland). Two are bays sheltered by sand bars: Golfe de Fos (French Mediterranean); and Ria Formosa (Portuguese Algarve). Together they exemplify a range of hydrographic and enrichment conditions. The project aims to understand the physical, biogeochemical and biological processes, and their interactions, that determine the trophic status of these coastal marine RRE through the development of simple screening models to define, predict and assess eutrophication. This paper introduces the sites and describes the component parts of a basic screening model and its application to each site using historical data. The model forms the starting point for the OAERRE project and views an RRE as a well-mixed box, exchanging with the sea at a daily rate E determined by physical processes, and converting nutrient to phytoplankton chlorophyll at a fixed yield q: It thus uses nutrient levels to estimate maximum biomass; these preliminary results are discussed in relation to objective criteria used to assess trophic status. The influence of factors such as grazing and vertical mixing on key parameters in the screening model are further studied using simulations of a complex‘research’ model for the Firth of Clyde. The future development of screening models in general and within OAERRE in particular is discussed. In addition, the paper looks ahead with a broad discussion of progress in the scientific understanding of eutrophication and the legal and socioeconomic issues that need to be taken into account in managing the trophic status of RREs.
- Evaluation of eutrophication in the Ria Formosa coastal lagoon, PortugalPublication . Newton, Alice; Icely, John; Falcão, Manuela; Nobre, A.; Nunes, J.; Ferreira, J.; Vale, C.The Ria Formosa is a shallow mesotidal lagoon on the south coast of Portugal, with natural biogeochemical cycles essentially regulated by tidal exchanges at the seawater boundaries and at the sediment interface. Existing data on nutrients in the water column and the sediment, together with chlorophyll a and oxygen saturation in the water column,compared using different models for assessing eutrophication. The European Environmental Agency criteria are based on the comparison of nutrient concentrations which indicate that the situation in the Ria Formosa is ‘‘poor’’ to ‘‘bad’’. In contrast, the United States Estuarine Eutrophication Assessment is based on symptoms, including high chlorophyll a and low oxygen saturation, which indicate that the Ria Formosa is near pristine. Despite these contradictions, a preliminary assessment by Driving forces, Pressures, State, Impact, Reponses(DPSIR) of eutrophication demonstrate the potential for episodic eutrophic conditions from treated and untreated domestic effluent as well as from non-point source agricultural run off. Sediments are also an important source of nutrients in the lagoon, but their contribution to potential eutrophic conditions is unknown.
- Management of coastal eutrophication: integration of field data, ecosystem-scale simulations and screening modelsPublication . Nobre, A.; Ferreira, J.; Newton, Alice; Simas, T.; Icely, John; Neves, R.A hybrid approach for eutrophication assessment in estuarine and coastal ecosystems is presented. The ASSETS screening model (http://www.eutro.org) classifies eutrophication status into five classes: High (better), Good, Moderate, Poor and Bad (worse). This model was applied to a dataset from a shallow coastal barrier island system in southwest Europe (Ria Formosa), with a resulting score of Good. A detailed dynamic model was developed for this ecosystem, and the outputs were used to drive the screening model. Four scenarios were run on the research model: pristine, standard (simulates present loading), half and double the current nutrient loading. The Ria Formosa has a short water residence time and eutrophication symptoms are not apparent in the water column. However, benthic symptoms are expressed as excessive macroalgal growth and strong dissolved oxygen fluctuations in the tide pools. The standard simulation results showed an ASSETS grade identical to the field data application. The application of the screening model to the other scenario outputs showed the responsiveness of ASSETS to changes in pressure, state and response, scoring a grade of High under pristine conditions, Good for half the standard scenario and Moderate for double the present loadings. The use of this hybrid approach allows managers to test the outcome of measures against a set of well-defined metrics for the evaluation of state. It additionally provides a way of testing and improving the pressure component of ASSETS. Sensitivity analysis revealed that sub-sampling the output of the research model at a monthly scale, typical for the acquisition of field data, may significantly affect the outcome of the screening model, by overlooking extreme events such as occasional night-time anoxia in tide pools.
- A methodology for defining homogeneous water bodies in estuaries e application to the transitional systems of the EU Water Framework DirectivePublication . Ferreira, J.; Nobre, A.; Simas, T.; Silva, M.; Newton, Alice; Bricker, S.; Wolff, W.; Stacey, A.; Sequeira, A.A methodology is developed and tested for division of estuarine and coastal systems into water bodies for monitoring and management purposes. This division is often implicit in the choice of sampling stations and in pollution abatement measures applied to different locations e it is now an explicit requirement of European Union Directive 2000/60/EC (Water Framework Directive) and recommended by United States Agencies such as EPA and NOAA. The approach considers both natural characteristics and the human dimension, by means of a stepwise methodology, which considers, on the one hand, morphology and salinity distribution, and, on the other, appropriate indicators of pressure and state. In the present application, nitrogen and phosphorus loading was used as the pressure component and chlorophyll a and dissolved oxygen as indicators of state. The criteria for system division were defined based on (1) an adimensional shape factor and salinity classes for the natural component; and (2) a normalised pressure index and (ASSETS) eutrophication symptom classes for the human dimension. Water quality databases and GIS were used to develop spatial distributions for the various components, and the results were aggregated into a final water body division, using tidal excursion as a ‘‘common sense’’ test. The methodology was applied to three well-studied systems in Portugal, a tubular estuary (Mondego), a wide lagunal estuary (Sado) and a coastal barrier island system (Ria Formosa). Although a final definition of water bodies will usually be a policy decision, this type of approach for the division of coastal systems into management units scientifically informs the decision-making process.
- Optimized exploitation of aquifers: application to the Querenca-Silves aquifer systemPublication . Ferreira, J.; Cunha, M. C.; Vieira, J.; Monteiro, José Paulo; Brebbia, C. A.; Popov, V.A great deal of optimization models have been developed to support aquifer planning and management with the goal of arriving at the best decisions in relation to the number and siting of infrastructures to be built and how to operate them. A mixed-integer multi-objective linear model has been taken from the literature to define the best decision for the development of the aquifer of Querenca-Silves (Portugal). It identifies efficient solutions for the location and design of pumping stations and their catchment area to supply a given number of demand centers, without disregarding the effect of groundwater management on the piezometric surface of aquifers and the many facets of groundwater management. The multi-objective model includes two objectives: (1) the minimization of aggregate water elevation height, and (2) the minimization of aggregate water transport length, weighted by the flows conveyed from the facilities to the centers. The effect of groundwater extraction on the piezometric surface of the aquifer is modelled with a response matrix method, with the establishment of maximum drawdown to prevent over-exploitation.
- Population genetics of Zostera noltii along the west Iberian coast: Consequences of small population size, habitat discontinuity and near-shore currentsPublication . Diekmann, O. E.; Coyer, J. A.; Ferreira, J.; Olsen, J. L.; Stam, W. T.; Pearson, G. A.; Serrão, EsterThe effects of oceanographic patterns on marine genetic biodiversity along the SW Iberian Peninsula are poorly understood. We addressed the question of whether gene flow in this region depends solely on geographic distance between isolated patches of suitable habitat or if there are superimposed effects correlated with other factors such as current patterns. Zostera noltii, the dwarf eelgrass, is the keystone habitat-structuring seagrass species on intertidal mudflats along the Iberian west coast. We used 9 microsatellite loci to analyze population genetic diversity and differentiation for all existing 8 populations from NW Spain (Ria de Vigo) to SW Spain (Puerto Real, Cadiz). Populations are highly genetically differentiated as shown by high significant FST,Wright’s fixation index, (0.08 to 0.26) values. A neighbor-joining tree based on Reynold’s distances computed from allele frequencies revealed a split between northern and southern populations (bootstrap support of 84%). This pattern of differentiation can be explained by (1) ocean surface current patterns present during Z. noltii’s reproductive season which cause a dispersal barrier between the northern and southern populations of this region, (2) habitat isolation, due to large geographic distances between suitable habitats, preventing frequent gene flow, and (3) small effective population sizes, causing high drift and thus faster differentiation rates.