This paper deals with wind-induced flows in a semi-enclosed water body in a microtidal environment that is subject to various wind-wave and river discharge conditions. The resulting currents are analyzed using numerical models supplemented by (and calibrated with) field observations. The emphasis is on the driving efficiency of wind fields in generating steady currents as a function of wind velocity and direction. The circulation generated is analyzed for the actual case of Cullera Bay and for a theoretical case in which the cape (limiting barrier) has been “removed” from the computational domain. The results obtained as a part of the EU research project ECOSUD, allow the barrier effect exerted by the cape to be partially quantified. The river plume dimensions and direction of spread are clearly influenced by the cape barrier. On a more local scale, the effluent discharge from the outfall was also found to be influenced by the two Júcar River jetties. Based on these results, a “retention” index that partly characterizes water quality in the bay is defined. This type of index is also a scientifically based indicator that supports more sustainable management of water quality in coastal bays of this type.

Cullera Bay is an example of a multi-source polluted coastal environment. The water quality in the bay is highly affected by pressure from major agricultural and industrial activities in the river basin. Fresh water is taken from the river and later returned, loaded with pesticides and fertilizers. Partially treated wastewater from riverbank towns and industries is discharged into the lower reaches of the river. This mechanism contributes to river pollution. The dramatic increase in Cullera's population during the summer tourist season and the limited capacity of the local water treatment plant also make it difficult to dispose of domestic wastewater, some of which is discharged untreated into the river or directly into the sea through a marine outfall. This freshwater input from the Júcar River and the marine outfall produces a highly polluted estuarine plume in the coastal region (with significant salinity gradients and complex spatial patterns), which is highly influenced by the hydrodynamics of the bay. Because of the discharge from the Júcar River, the sewage from the marine outfall and the particular geomorphological features of Cullera Bay, this plume may play a significant role in defining and supporting different aspects of the socioeconomic environment in neighboring areas, especially those related to water quality. However, the mean water quality in the bay does not depend only on the surface circulation pattern but also on the overall marine circulation in the water body, where the local bathymetry has more relative influence. Therefore, it is important to have the tools and capabilities needed to monitor and characterize the actual pollutant dispersion drivers (wind and hydrodynamics) to assess their influence at local and regional levels. This paper presents the characterization of the wind field and circulation pattern in Cullera Bay using data acquired during seven field campaigns. The analysis shows that there is strong seasonal behavior in the wind field, ranging from daily breeze patterns to persistent offshore winds. Although the wind field varies greatly throughout the year, the overall pattern mainly consists of daily breezes. However, the hydrodynamic field has proved to be very complex and, with a few exceptions, poorly correlated with the wind-field pattern. This poor correlation may be due to a nonhomogeneous wind field in Cullera Bay caused by a nearby mountainous barrier. Despite the complexity of the hydrodynamic field in each campaign, the overall analysis of the nearshore current pattern shows a strong “boundary condition” influence that mainly follows the isobaths rather than the wind field. The influence of the topography on the wind and currents may have significant implications for quantifying the relative importance of pollutant sources that harm the quality of the water in Cullera Bay.

Water quality plays a very important role in the ecological balance and economic development of coastal and estuarine areas. However, these areas have been progressively degraded in recent decades due to different factors, including an increase in nutrient and pollutant loads introduced into the system, which may cause eutrophication problems. This paper analyzes the water quality of one such area, Cullera Bay, located on the Spanish Mediterranean coast. This study focuses on the main sources and sinks of pollutant substances and the relationship between the distribution of these substances within the bay and local meteorological and oceanographic conditions. Two main sources of nutrients and pollutants were identified: the discharges of the Júcar River and the marine outfall, although other secondary sources are also present. The river discharge varies greatly depending on the season. The freshwater it carries is very rich in nutrients due to the presence of fertilizers and pesticides from its agricultural use. The domestic wastewater discharged through the marine outfall is occasionally untreated, particularly in the summer, when the tourist population increases and the capacity of the water treatment plant is exceeded. This study is based on data recorded during nine field campaigns carried out in the area in 2002 and 2003 and numerical simulations of hydrodynamics and pollutant dispersion. By analyzing the field data and the numerical simulation results, wind is identified as the main driving factor in the bay because the other possible driving factors either have negligible effects (tide), affect only a very localized area (waves, usual river discharges) or are infrequent (storm surges, river floods).

The Júcar River, characterized by a very irregular freshwater flow, discharges into the Spanish Mediterranean coastal waters. However, the flow at its mouth is usually insignificant due to the overexploitation of upstream water. Under normal conditions, the final stretch of the river (downstream from the Cullera weir) is nurtured only by water released from the weir and small discharges from lateral irrigation channels. During periods of heavy rain, however, a significant amount of water flows through the Cullera weir. An analysis of data acquired during several field campaigns in Cullera Bay clearly reveals a zonal distribution of nutrients and chlorophyll-a within the bay: a southern area of continental influence, located near the mouth of the Júcar River; a region affected by karst filtrations and minor freshwater inputs, located to the north of the bay around Cullera Cape; and a third zone in between, characterized by higher salinities. Spatial salinity distribution is indicative of the spatial distribution of some of the nutrients discharged by the river, particularly nitrite, nitrate, orthosilicic acid and total phosphorus (TP), since it has been shown that their behavior is inverse to that of salinity. However, neither soluble reactive phosphorus (SRP) nor ammonium, which are mainly affected by biological activity, show this type of behavior. Five different conditions/scenarios were identified during the overall sampling period based on the time-series analysis of wind parameters, rainfall, freshwater flow, salt-wedge thickness at the measuring station on the river, and by comparing the average surface salinity at the sea stations with the values obtained at the coastal stations.

The Júcar River flows into Cullera Bay in the western Mediterranean Sea (Valencia, Spain). The river flow is over-exploited and usually has no significant discharge at the mouth, except during very rainy periods. As part of the ECOSUD project, nine sampling campaigns were carried out (June 2002–July 2003) at different stations and depths in the Júcar Estuary and Cullera Bay. This paper presents the nutrient analyses of two campaigns (summer and spring) with different weather conditions (without and with freshwater flow respectively). The results show that the freshwater layer of the river was higher in the spring campaign (April) than in the summer campaign (July), which resulted in a more evident freshwater influence at the marine stations near the river mouth. As expected, there was a general downward trend in the dissolved nutrient concentrations with lower river flow (lower continental influence). However, the variations observed were not always linear. With some exceptions, nutrient concentrations generally increased. Ammonium, SRP and orthosilicic acid increased due to the senescence, death and subsequent mineralization of freshwater organisms as salinity increased. Nitrate and nitrite also increased somewhat due to the nitrification of the ammonium. However, nitrite showed some losses in summer conditions (July) related to the different speeds of the two nitrification steps.

Mangueira Bay is located south of Patos Lagoon. It receives poorly treated official and clandestine household and industrial effluents from the city of Rio Grande. This study analyzes parameters that characterize the water quality of Mangueira Bay at various sites influenced by effluent discharge from different activities carried out in the surrounding area. These data are also useful for water-quality models. Water was sampled under various salinity conditions in October 2002 (spring), June 2003 (winter), December 2003 (summer) and April 2004 (fall). Because sewage discharge is relatively constant, water contamination is highly dependent on the association between industrial activity and hydrodynamics. The simultaneous combination of nitrogenous and phosphatic nutrient inputs causes serious eutrophication problems and an excessive increase in vegetal biomass in Mangueira Bay. An assessment of bacteria, greases and oils indicates that the water contamination near the city of Rio Grande comes not only from domestic sources but also from wastewater from fish plants and a local petroleum refinery. In order for Mangueira Bay to meet the requirements based on its water classification under federal law and enforced by environmental agencies, the discharge of clandestine domestic and industrial effluents with no or insufficient treatment must be avoided because the survival of artisanal fishing and natural species depends on the proper preservation of this complex aquatic environment.

This paper presents the results of phytoplankton counts carried out with epifluorescence at five sampling stations: two in the Júcar River Estuary and the other three in the region of freshwater influence of the Júcar River. From June 2002 to July 2003, nine sampling campaigns were carried out as a part of the EU's ECOSUD project. Two of these campaigns (the 2nd and 8th) were selected for analysis. These sampling campaigns represent two different conditions: in the 2nd campaign the discharge of the Júcar River was almost null, while in the 8th campaign it was significantly higher.

Along the salinity gradient, as the influence of fresh water and nutrient loads decreases, a decrease in the population density of eukaryotic phytoplankton was observed. Typical freshwater phytoplankton groups (colonial cyanobacteria and chlorophyceae) clearly decrease in density and percentage as salinity increases. In general, picocyanobacteria exhibit the opposite behavior. The behavior pattern of groups with species adapted to fresh water and seawater is less clear. The density of these groups (diatoms and prymnesiophytes) is highest in the salt-wedge area due to nutrient accumulation. However, the densities are generally higher at the freshwater stations than in the marine environment. The vertical distribution at the estuarine stations shows clear density maximums in the interface area, which seems to have two causes: the retention of senescent phytoplankton affected by saline shock in this quiescent area and the growth of phytoplankton that exploit the accumulated nutrients.

Mangueira Bay is located in southern Brazil (between 30° and 32° south latitude). It is a significant regional resource that lends itself to activities such as tourism, fishing, and fish and shellfish breeding. Studies performed by Rio Grande University (FURG) have demonstrated that, due to its natural conditions, Mangueira Bay is an area of shelter and feeding for the local biota. As a result, the possibility of implementing intensive shrimp breeding has been analyzed. It is therefore important to study the hydrodynamics, water quality and sediments of this water body. This paper describes the spatial and temporal distribution of heavy metals in sediments during monitoring campaigns carried out in October 2002 and June 2003 as a part of the “Estuaries and Coastal Areas. Basis and Tools for a More Sustainable Development” (ECOSUD) project. The distribution of metals in the bed was estimated as well as the potential for resuspension due to the waves caused by typical storm conditions similar to those measured in the May 2003 campaign. This sediment resuspension in the seabed can repollute the water column. Classic expressions were used to estimate the wind-induced water waves, the resuspension rate and the concentration of suspended material. The results show differences in spatial distribution between the two campaigns, but in both cases the south of Mangueira Bay was found to be the proper area for aquaculture. Furthermore, in all of the sediment samples analyzed, the different metals were present in concentrations under the limits stipulated by the Canadian Environmental Quality Guidelines of the Canadian Environmental Protection Agency (CEPA). The calculation of sediment resuspension demonstrated that conditions favor shrimp breeding along the southwest coast under typical winds from the west, especially in the southern part of Mangueira Bay.

This study identifies the most abundant and significant species—from an ecological point of view—in the soft bottom of Cullera Bay (Spain) in order to study the seasonal (summer–winter) variations in the local communities of polychaete annelids and bivalve mollusks. This paper presents the results of the analysis of samples taken during two field campaigns (July 2002 and February 2003) of a series of five campaigns carried out in 2002 and 2003. For these field observations, twelve sampling stations were set up in the bay along three transects. At these stations, macrobenthos was collected using a Ponar grab. Only polychaete annelids and bivalve mollusks were selected from the samples since they made up most of the benthic abundance and biomass respectively. Undisturbed sediment samples were also taken at the same stations to evaluate the influence of environmental factors on these benthic communities. The granulometry, organic matter content, total nitrogen and total phosphorous of these samples were studied. Seasonal-abundance diagrams were obtained for the most abundant groups of species (bivalves and polychaetes) in order to study the macrobenthic fauna associated with the various soft-bottom facies of Cullera Bay and their seasonal patterns. The results show that both polychaetes and bivalves reached their highest total density values in the summer. The assemblages were dominated by Donax trunculus, Donax semistriatus, Spisula subtruncata, Dispio uncinata, Prionospio caspersi and Scoletoma impatiens, whereas the most abundant species were Donax semistriatus, Spisula subtruncata, Dispio uncinata and Prionospio caspersi in the summer and Donax trunculus and Scoletoma impatiens in the winter.

Freshwater plumes in continental and shelf seas are common, relevant features of the coastal environment and its management. In order to analyze and predict the overall shape and scale of freshwater plumes, the well-known hydrodynamic model COHERENS was used to perform several simulations of river-plume evolution. The area considered in this study has an idealized straight coastline with longitudinally uniform bathymetry and a constant bottom slope. In this domain, constant river discharge is assumed with an outflow rate ranging from that of typical mean conditions for small-scale Mediterranean rivers (e.g., Júcar) to that of larger-scale ones (e.g., Ebro). A simplified version of the underlying mesoscale circulation is considered and the effects of wind-forcing on the evolution of the freshwater plume are taken into account by considering different wind scenarios. This study describes the physical characteristics and associated dynamics of a river plume as a function of the river-flow magnitude for a Mediterranean-type receiving water body. The results of numerical simulations allow us to assess the relative importance of different factors (e.g., river-flow rate, wind parameters, etc.) on the overall dynamics and physical characteristics of the freshwater plume (including both alongshore and across-shore length scales).

Mangueira Bay is a semi-enclosed system that is very important to the communities living around the city of Rio Grande. It is influenced by multiple and conflicting human impacts. This embayment is connected to Patos Lagoon Estuary through a narrow inlet and its dynamics seem to be related to the dynamics of the estuarine area. This study aims to investigate the mechanisms that control the dynamics of Mangueira Bay under the predominant forcing conditions and evaluate the influence of baroclinic estuarine circulation on the dynamics of the area.

The TELEMAC-2D model was used to carry out two- and three-dimensional simulations of Patos Lagoon Estuary. The modeling results indicate that the dynamics of Mangueira Bay are directly related to the dynamics of the main access channel, which are controlled by a combination of remote and local wind effects. A time lag occurs between the excursion of salt in Mangueira Bay and the excursion of salt in the main channel, with salinity penetrating in the embayment when winds from the SW become weaker. Marked horizontal stratification is present throughout the embayment, with salinity gradients changing direction as a function of ebb and flood currents. The area where the embayment connects to the main channel presents higher salinity variability and vertical stratification, while the inner limits are less affected by the dynamics of the channel.

This paper presents a two-dimensional hydrodynamic model of Patos Lagoon carried out within the framework of ECOSUD (Estuaries and Coastal Areas. Basis and Tools for a More Sustainable Development), a research project financed by the European Community. This lagoon is located in the southern Brazilian state of Rio Grande do Sul, between the cities of Rio Grande and Porto Alegre. It is approximately 250 km long, runs parallel to the coast and has an area of 10,360 km². The estuarine area is 60 km long. It receives major tributaries, which bring pollutants from farms and industry and also from waste from nearby cities like Pelotas and Rio Grande. Due to the importance of this resource and the problems presented for economic and recreational activities, numerical studies must be carried out to characterize the hydrodynamic behavior of various potentially productive areas such as Mangueira Bay. This hydrodynamic characterization complements water-quality studies in this area, and both act as inputs for aquaculture and water-resources planning. Different simulations were carried out with a two-dimensional model, RMA-2 (USACE), under a combination of several forcing agents during specific periods. These simulations were calibrated and validated with the available data.

This paper presents the results of satellite-image digital processing. The area of study covered Patos Lagoon (southern Brazil). Suspended matter distribution was used as conservative traces. Circulation patterns and their changes over time were also characterized. The process involved fitting an empirical relation function between digital intensity values for selected bands of the spectra (optical properties) and the values measured in situ corresponding to the satellite data. The 1999 and 2001 field campaigns involved measurements of suspended matter, water surface temperature and wind direction and velocity inside the lagoon. The lagoon covers nearly 10,360 km². It is 250 km long along its NE-SW axis and 40 km wide. We applied algorithms widely used in remote sensing in our methodology. First, we generated maps of the spatial distribution of selected parameters. After that, we extracted the boundaries to define areas with constant reflectivity associated with the isoconcentration of suspended matter and zones of equal temperature (isothermal). We evaluated images with different hydrologic time series, including high, medium and low discharges from tributaries. This allowed us to identify the plumes of rivers, their size and changes over time, and the general circulation of different water masses inside Patos Lagoon.

Over the last ten years, catches of the pink shrimp Farfantepenaeus paulensis by artisanal fishermen in the Patos Lagoon Estuary (southern Brazil) have been decreasing. This has created economic and social problems for approximately 3500 families, who rely on this activity as their main source of income. In an attempt to solve these problems, the Mariculture Laboratory of the University of Rio Grande (FURG) has developed a technological package for the pen culture of this species in the estuarine area. This culture system requires low investment, is easy to manage and allows fishermen to continue their normal activities. This study evaluates the influences that this culture may have on the macrobenthic communities surrounding the enclosures. The experiment was carried out around a 0.3 ha pen placed in the estuarine area adjacent to Marinheiros Island (Rio Grande county). This area has a central channel over 5 meters deep and shallow areas less than 1.5 meters deep near the shore, where the pen was installed. Two linear transects were carried out in opposite directions parallel to the shoreline, starting from the edge of the pen. Monthly water and sediment samples were collected 5, 15, 30 and 100 m from the pen to evaluate oxygen consumption, chlorophyll-a, total phosphorus and total nitrogen concentrations. Characterization of the macrobenthic community revealed the presence of Laeonereis acuta, Nephtys fluviatilis, Neanthes sp., Kalliapseudes schubartii, Callinectes sapidus, Erodona mactroides, Heleobia australis, Heteromastus similis and isopods. Significant differences in the diversity and abundance of the species were detected between the samples, especially at the closest point to the pen, where more H. similis specimens were found. No significant differences in oxygen consumption, total nitrogen or total phosphorus concentrations were found between the sampled points. These results demonstrate that this kind of culture system does not influence water quality in the surrounding area. The higher abundance of H. similis near the pen (1 m) demonstrated a very limited impact on the macrobenthic community. Organic matter accumulation zones created by the presence of the pen might favor the presence of H. similis, which is a deposit feeder. This result could become more significant if the culture conditions are intensified or more pens are installed.

In recent years, aquaculture has been growing all over the world. In the estuarine region of Patos Lagoon (southern Brazil), small pilot shrimp farms are being developed by the Mariculture Laboratory at the FURG. Despite its current growth, environmental information on the appropriate places for its development and expansion is lacking, making it a high-risk activity. In this study, GIS tools are used to identify the most appropriate aquatic sites for small shrimp farms and present a methodological approach for the spatial planning of aquaculture in the Patos Lagoon Estuary. The main criteria taken into account are accessibility, proximity of fishing villages, distance from pollution sources, salinity, bathymetry and legal constraints. An integrated analysis of these parameters using spatial analysis techniques is carried out. This powerful method brings together a variety of data for decision-making in aquaculture. The result is a continuous surface ranging from the least suitable to the most suitable places for shrimp farming. This information will be useful in the decision-making process for guiding aquaculture planning and informing stakeholders in order to appropriately develop and manage the coast in this area.

Developing countries in the technological transition period seek fast economic growth and give environmental issues lower priority. This is one of the causes of environmental degradation in coastal zones. The Patos Lagoon Estuary, located along the southern coast of Brazil, has accumulated environmental liabilities over the last 30 years due to socioeconomic activities in the city of Rio Grande. These liabilities are particularly conspicuous in the shallow estuarine embayments, which are considered vital habitats due to their high productivity and significance as nurseries (shelter and feeding) for the local biota. Since the 1970s, these habitats have suffered various stressors from uncontrolled urban and industrial expansion, which are responsible for landfills at the estuary shores and the enrichment of the water with nutrients and metals from the disposal of effluents. In the medium to long term, these problems tend to be aggravated by existing projects and policies of industrial and port expansion. One of the most productive environments in this estuary is Mangueira Bay, an oval semi-enclosed bay located south of the city with an area of 23 km² and a depth mostly below 1.5 m. This embayment is currently a focus of land/water use conflicts involving several social actors, including fishermen, socially excluded people, high-class housing users, public institutions, industries and the general population. In this context, finding a solution that is appropriate and compatible with all social demands on the environmental goods and services provided by the estuary is a difficult task. The process must begin with a technical diagnosis that is extensive and detailed enough to include social, economic and environmental issues. This paper describes the use conflicts of Mangueira Bay and suggests guidelines for a collective management plan.

The analysis of the environmental and social impact of alternative management policies for coastal ecosystems requires, with increased urgency, a process of socioeconomic appraisal (or valuation) to obtain specific quantitative performance indicators to design effective management interventions. This paper proposes an integrated, ecosystem-based, functional, dynamic, anthropogenic approach to studying and analyzing the various factors, activities and processes that take place in the use and exploitation of coastal zones. This approach is applied to two sites (the Jucar River Estuary in Spain and the Patos Lagoon in Brazil) using a quantitative model that gathers and integrates the diverse range of interactions and functional relationships that shape and determine the ecosystem's performance (i.e. biological, environmental, economic, technological and social aspects) through an objective function. A net socioeconomic benefit function is postulated as the objective function to be optimized (maximized) over time, subject to the various constraints imposed by the legal and institutional framework, economic environment, resources, ecosystem dynamics and other factors. In both cases, four alternative management scenarios are considered.

The results show that improvements in water quality result in increased regional benefits in sectors that depend on water quality levels. In these cases, the marginal cost of cleaning up 1 m³ of water is lower than the marginal benefits obtained from 1 m³ of purified water. Therefore, the operation of water treatment plants improves the socioeconomic benefits to both regions by improving water quality (which in turn improves social welfare).