Resumen: En un estudio comparativo en el cual se utilizó el híbrido de tilapia Oreochromis mossambicus × Oreochromis aureus cultivado en agua de mar y en agua dulce no se observaron diferencias significativas en el desempeño como crecimiento en peso e índices biológicos (e.g., conversión alimenticia y supervivencia) después de 90 días de experimentación. Se utilizó un alimento común elaborado en el laboratorio que contenía 40% de proteína cruda y 8.5°% de grasa cruda. Para la formulación del alimento, se utilizó harina de pescado y harina de subproducto de ave (50:50) como fuente de proteína. El estudio se realizó utilizando sistemas de recirculación y organismos de 25.0 ± 0.06 g y 24.70 ± 0.32 g para los tratamientos de agua de mar y agua dulce, respectivamente, con 4 repeticiones por tratamiento. Al finalizar el experimento los peces alcanzaron un peso de 161.80 ± 12.78 g y 167.60 ± 7.29 g, respectivamente. El coeficiente térmico de crecimiento fue de 0.91 y 0.89 (agua de mar vs agua dulce), y no se observaron diferencias significativas. Sin embargo, la digestibilidad aparente tanto en materia seca como por nutriente (proteína, lípidos y carbohidratos) resultó significativamente mayor para los organismos en agua de mar. La digestibilidad pudiera estar asociada a una mayor actividad enzimática en presencia de una fuerza iónica mayor. El estudio de respirometría indicó que la relación O:N fue similar entre los organismos en agua de mar y los organismos en agua dulce, con valores de 21 y 18, respectivamente. Lo anterior sugiere que esta variedad de tilapia presenta un catabolismo combinado de proteínas y lípidos como sustratos de energía. Se concluye que esta variedad de tilapia puede adaptarse y desarrollarse en un ambiente marino, lo cual puede contribuir a ampliar su forma de producción. | Abstract: In a comparative study using the hybrid tilapia Oreochromis mossambicus × Oreochromis aureus grown in seawater and freshwater, no significant differences in growth performance (weight gain) and biological indices (e.g., feed conversion efficiency and survival) was observed after 90 days of experimentation. A common feed was formulated to contain 40% crude protein and 8.5% crude fat. Fish meal and poultry by-product meal (50:50) were used as a source of protein in the formulation. The study was conducted using recirculation systems and organisms already adapted to seawater and freshwater with an initial weight of 25.0 ± 0.06 g and 24.70 ± 0.32 g, respectively (four replicates per treatment); at the end of the experiment their final weight was 161.80 ± 12.78 g and 167.60 ± 7.29 g, respectively. The thermal growth coefficient was 0.91 and 0.89 (seawater vs freshwater), and there were no significant differences; however, the apparent digestibility of dry matter as well as per nutrient (protein, lipid, and carbohydrate) was significantly higher for the organisms in the seawater treatment. The digestibility could be associated with greater enzymatic activity in the presence of higher ionic strength. The respirometric study indicated that the O:N ratios were similar for organisms reared in seawater and freshwater, with values of 21 and 18, respectively. This indicates that this strain of tilapia uses a mixture of proteins and lipids as energy substrates. We conclude that this strain of tilapia has the potential to adapt and thrive in a marine environment and that its production practices could be expanded.

O objetivo deste trabalho foi testar a sobrevivência de alevinos de jundiá a diferentes concentrações de salinidade (sal marinho comum e água do mar), pois o sal é indicado no tratamento de algumas doenças e também para reduzir o estresse durante o manuseio e transporte de peixes. Os alevinos (1,68 &plusmn; 0,87g) permaneceram de 3 a 7 dias em tanques de 1400l, com água corrente e temperatura entre 23 e 25&deg;C, sendo alimentados diariamente. Após esse período, foram colocados 50 alevinos em tanques de 250l, com circulação fechada, biofiltro e aeração constante. A concentração da água nos tanques foi de 8,0; 9,0; 9,25; 9,50 e 10,0g/l de sal marinho comum ou 10,0; 12,0 e 14,0‰ de água do mar artificial. A sobrevivência dos alevinos foi observada ao longo de 96h. Para cada grupo de testes houve um grupo controle nas mesmas condições, mas com salinidade de 0‰. Não houve mortalidade e alteração do comportamento nos grupos expostos a 8g/l sal marinho comum e a 10‰ água do mar. O grupo exposto a 9g/l sal marinho comum também não apresentou mortalidade, mas houve alteração do comportamento alimentar. O aumento da concentração de sal marinho comum ou da água do mar causou uma elevação da porcentagem de mortalidade e alteração do comportamento alimentar. Como R. quelen suportou sal marinho comum até 9g/l pelo período de 96h, o mesmo pode ser testado na prevenção ou tratamento de doenças e na redução do estresse durante o transporte.<br>The aim of this study was to analyze the survival of fingerlings of Rhamdia quelen to different concentrations of salinity (common marine salt and seawater). Salt is used in the treatment of some fish diseases and to reduce the stress of handling and transport. Fingerlings (1.68 &plusmn; 0.87g) were kept in a 1400l tank with running freshwater at 23-25&deg;C, for 3 to 7 days, being fed daily. Later groups of 50 specimens were transferred to 250l tanks with a water re-use system. The water concentration was 8.0, 9.0, 9.25, 9.5, or 10.0g/l common marine salt or 10.0, 12.0, or 14.0‰ artificial seawater. Survival was observed over a period of 96h. The control group was maintained in the same conditions, but with salinity of 0‰. There was no mortality and change of behavior in the groups exposed to 8g/l common marine salt and to 10‰ seawater. The group exposed to 9g/l common marine salt also did not show mortality, but there was an alteration of the feeding behavior. Higher concentrations of common marine salt or seawater increased mortality and provoked changes in the feeding behavior. Since R. quelen tolerated common marine salt up to 9g/l for 96h, salt can be tested to prevent or treat diseases and to reduce the stress of transport.

Es un hecho reconocido que la contaminación por metales traza representa uno de los mayores factores de riesgo para los organismos marinos costeros, los que se encuentran expuestos a ellos por efecto de las descargas de efluentes industriales y urbanos en bahías y estuarios, además muchos de estos metales participan en ciclos biológicos de diferentes organismos lo que afecta su distribución y abundancia. Paralelamente, se han realizado varios estudios para evaluar el efecto de los compuestos eliminados por actividades antropogénicas midiendo su concentración en agua, sedimentos y organismos. En este contexto, los bivalvos han sido ampliamente utilizados como indicadores de contaminación de sistemas costeros, ya que por su carácter de organismos sésiles están permanentemente expuestos a los efectos de estas sustancias, por lo que han sido utilizados como biomonitores. Considerando que Perumytilus purpuratus se encuentra distribuido ampliamente a lo largo de la zona intermareal de Bahía San Jorge, (II Región) y la existencia de varias descargas industriales y municipales provenientes de la ciudad de Antofagasta, en este trabajo se ha utilizado este mitílido como organismo monitor para evaluar los cambios en las concentraciones de metales en la columna de agua de la bahía, lo que se puede reflejar en el contenido de metales en él, en relación a la cercanía de las potenciales fuentes de metales<br>It is well known that trace metal pollution if one of major risk factors for coastal organisms who are exposed to the effects of industrial and urban discharges in bays and estuaries. In addition, it is also known that trace metals are involved in several biological cycles of different organisms, affecting their abundance and distribution. Several studies to evaluate the effects of the discharge of anthropogenic activities have been made, measuring the concentration of pollutants in water, sediments and organisms. In this context, bivalves have been used widely as index of coastal pollution processes, since they are sesile and are exposed permanently to the effect of these subtances allowing them being used as biomonitors. Considering that Perumytilus purpuratus is distributed widely along the intertidal zone of San Jorge Bay (Region II, Chile) and the presence of several industrial and urban discharges from Antofagasta City, in this paper this bivalve was used to monitoring the trace metal concentrations in bay waters which might be reflected in the trace metal content in this organism, as function to the location of metal potential sources

The Agua Amarga coastal aquifer has been the object of a succession of anthropogenic interventions over the last 90 years: (a) the operation of saltworks from 1925 to 1975; (b) the withdrawal, since 2003, of groundwater from the aquifer along the coast line; and (c) the programme of pouring seawater over the salt marsh, carried out since 2009, to recover the piezometric levels and the soil moisture conditions. For a better understanding of how these past and present human activities have affected the natural groundwater regime, and to validate certain hypotheses concerning the interpretation of experimental data on temperature depth profiles and piezometric and salinity changes, a numerical fluid flow and solute transport model was designed and applied to the period 1925–2010, using SEAWAT. This model reproduces, in a qualitative and quantitative way, the flow and transport processes that operated during this time, as well as the behaviour of the seawater wedge.

A shallow alluvial coastal aquifer in the Batinah area of Oman, with sea-water intrusion that extends several kilometres inland, has been studied experimentally, analytically and numerically. The water table is proved to have a trough caused by intensive pumping from a fresh groundwater zone and evaporation from the saline phreatic surface. Resistivity traverses perpendicular to the shoreline indicated no fresh groundwater recharge into the sea. Using an analytical Dupuit-Forchheimer model, developed for the plain part of the catchment, explicit expressions for the water table, sharp interface location and stored volume of fresh water are obtained. It is shown that by the pumping of salt water from the intruded part of the aquifer, this intrusion can be mitigated. Different catchment sizes, intensities of fresh groundwater pumping, evaporation rates, water densities, sea level, incident fresh water level in the mountains and hydraulic conductivity are considered. SUTRA code is applied to a hypothetical case of a leaky aquifer with line sinks modeling fresh water withdrawal and evaporation. The numerical code also shows that pumping of saline water can pull the dispersion zone back to the shoreline.

The aim of this study was to analyze the survival of fingerlings of Rhamdia quelen to different concentrations of salinity (common marine salt and seawater). Salt is used in the treatment of some fish diseases and to reduce the stress of handling and transport. Fingerlings (1.68 ± 0.87g) were kept in a 1400l tank with running freshwater at 23-25°C, for 3 to 7 days, being fed daily. Later groups of 50 specimens were transferred to 250l tanks with a water re-use system. The water concentration was 8.0, 9.0, 9.25, 9.5, or 10.0g/l common marine salt or 10.0, 12.0, or 14.0‰ artificial seawater. Survival was observed over a period of 96h. The control group was maintained in the same conditions, but with salinity of 0‰. There was no mortality and change of behavior in the groups exposed to 8g/l common marine salt and to 10‰ seawater. The group exposed to 9g/l common marine salt also did not show mortality, but there was an alteration of the feeding behavior. Higher concentrations of common marine salt or seawater increased mortality and provoked changes in the feeding behavior. Since R. quelen tolerated common marine salt up to 9g/l for 96h, salt can be tested to prevent or treat diseases and to reduce the stress of transport. | O objetivo deste trabalho foi testar a sobrevivência de alevinos de jundiá a diferentes concentrações de salinidade (sal marinho comum e água do mar), pois o sal é indicado no tratamento de algumas doenças e também para reduzir o estresse durante o manuseio e transporte de peixes. Os alevinos (1,68 ± 0,87g) permaneceram de 3 a 7 dias em tanques de 1400l, com água corrente e temperatura entre 23 e 25°C, sendo alimentados diariamente. Após esse período, foram colocados 50 alevinos em tanques de 250l, com circulação fechada, biofiltro e aeração constante. A concentração da água nos tanques foi de 8,0; 9,0; 9,25; 9,50 e 10,0g/l de sal marinho comum ou 10,0; 12,0 e 14,0‰ de água do mar artificial. A sobrevivência dos alevinos foi observada ao longo de 96h. Para cada grupo de testes houve um grupo controle nas mesmas condições, mas com salinidade de 0‰. Não houve mortalidade e alteração do comportamento nos grupos expostos a 8g/l sal marinho comum e a 10‰ água do mar. O grupo exposto a 9g/l sal marinho comum também não apresentou mortalidade, mas houve alteração do comportamento alimentar. O aumento da concentração de sal marinho comum ou da água do mar causou uma elevação da porcentagem de mortalidade e alteração do comportamento alimentar. Como R. quelen suportou sal marinho comum até 9g/l pelo período de 96h, o mesmo pode ser testado na prevenção ou tratamento de doenças e na redução do estresse durante o transporte.

The Agua Amarga coastal aquifer, located in the southeast of Spain (Alicante province) has suffered a significant decrease in its piezometric levels due to its use to supply water to Alicante I and II desalination plants. In order to recover its natural levels and to preserve the salt marsh of ecological interest linked to the aquifer, whose origin is related to ancient saltworks, a pilot scheme based on depositing seawater over the salt marsh surface has been carried out from December 2009 to July 2010. As a result, piezometric levels have increased by around 2 and 3 m below the salt marsh and a general decrease in groundwater salinity of between 15 and 100 g/l has been measured. A flow-transport numerical model with SEAWAT is used to assess and evaluate the seawater depositing programme.

Agua Amarga coastal aquifer in southern Spain has been the subject of chemical and physical measurements since May 2008 in order to monitor the potential effects of water withdrawal for the Alicante desalination plants on the salt marsh linked to the aquifer. Electrical conductivity contour maps and depth profiles, piezometric-head contour maps, hydrochemical analyses, isotopic characterizations and temperature depth profiles show not only the saltwater intrusion caused by water abstraction, but also the presence of a pronounced convective density-driven flow below the salt marsh; this flow was a consequence of saltwork activity in the early 1900s which generated saline groundwater contamination. The influence of a seawater recharge programme, carried out over the salt marsh in 2009–2010, on the diminishing groundwater salinity and the recovery of groundwater levels is also studied. Based on collected field data, the project provides a deeper understanding of how these successive anthropogenic interventions have modified flow and mixing processes in Agua Amarga aquifer.

Several groundwater endorheic base levels are known in different parts of the world. Some of them allow seawater encroachment into them. Two examples of such groundwater systems, at Lake Asal in the Afar Depression of East Africa and Lago Enriquillo in the Dominican Republic, have been modeled using FEFLOW. The simulated flow pattern reproduces the seawater encroachment all the way from the sea to the endorheic base level. When the water in that base level undergoes concentration to brine through evaporation, the dense brine starts to flow below the encroaching seawater body in the opposite direction toward the sea. These processes reach steady-state conditions in a relatively short time of several hundred years.

The behavior of aluminum and zinc alloys were evaluated and compared as sacrifice anodes in cathodic protection of aluminum NV-5083 hulls in seawater in Valparaíso bay. Samples of the aluminum alloy used to manufacture boat hulls and Al-Zn-In, Al-Zn-Sn, and Zn anodes were made. Electrochemical behavior was evaluated by means of polarization curves and corrosion potential as function of time. In parallel, galvanized pairs (boat hull-sacriice anode), were designed and immersed in the electrolyte for 16 days, determining the weight loss and evolution of the open circuit potential for each material. The results show that the aluminum based anodes provide the NV-5083 aluminum hull cathodic protection in seawater. However, they do not exceed the economical horizon and useful life of zinc anodes, because the aluminum based anodes present higher corrosion for the protection of a similar exposed area of aluminum | Se evalúa comparativamente el comportamiento de aleaciones de aluminio y cinc, como ánodos de sacrificio en la protección catódica de cascos de aluminio NV-5083 en agua de mar de la bahía de Valparaíso. Para ello se confeccionaron probetas de la aleación de aluminio empleado en cascos de lanchas y ánodos de Al-Zn-In, Al-Zn-Sn y Zn. Los comportamientos electroquímicos se evaluaron mediante curvas de polarización y potencial de corrosión en función del tiempo. Paralelamente, se diseñaron pares galvánicos de aleación del casco-ánodo de sacrificio, los cuales se sumergieron en el electrolito durante 16 días, determinándose la pérdida en peso y la evolución del potencial a circuito abierto de cada material. Los resultados muestran que los ánodos de base aluminio pueden proteger catódicamente el casco de aluminio NV-5083 en agua de mar, pero no logran superar el horizonte económico y de vida útil de los ánodos de cinc, debido a que presentan un mayor desgaste para la protección de igual área de aluminio