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The measurement of total fish biomass is an essential practice in the aquaculture management. The method commonly used which involves removing a sub-sample of fish from a tank, weighing it and extrapolating the result to the whole tank, carries a large error, is intense labor and causes great stress. Here, we tested a laser scanning method to estimate the total fish biomass from the total fish volume of a sole population (Solea senegalensis) in a tank. The ratio FB/FLV of fish biomass (FB), weighing the 100% of soles, versus the fish layer volume (FLV) measured by the laser scanning, is calculated. Different fish size (small and large) and stocking densities (very low, low, medium and high) were tested. To test the method in the worst conditions, in very low stocking density, fish were 3.0 g ± 1.1 (individual mean weight ± SD); but in low, medium and high stocking density fish were 234.0 g ± 84.6 (individual mean weight ± SD). The fish layer volume included the fish biomass and the interstitial water present among them, which can be estimated from the ratio FB/FLV. In medium and high rearing densities with larger fishthe ratio takes values very close to 1 (0.957 ± 0.021 and 0.967 ± 0.011) giving percentages of interstitial water lower than 5%. But in very low stocking density (0.4 kg/m2) with smaller fish (3.0 g ± 1.1), the ratioFB/FLV was much lower, giving a non-realistic percentage of interstitial water estimation. The low ratios obtained at very low stocking densities are due to the resolution of the image catching process, which is aggravated when working with small fish, since the error of a pixel from a digital image represents a larger percentage of error than with larger fish and higher stocking density. It should be noted that the coefficient of variation (CV) obtained was very low (in all cases lower than 7.2%) and decreased as the stocking density increased achieving the lowest value (1.1%) at high stocking density. The laser scanning has proven to be a, Postprint (published version)

Recirculating aquaculture systems (RAS) allow minimizing the water renewal flow rate needed in fish production by increased Nitrogen (NO3 ) and Phosphorous concentrations. Integrating seaweed production to RAS can improve its performances and reduce soluble wastes, contributing to a more sustainable production system., Postprint (published version)

Waste management in any aquacultural system, and specially in recirculating aquaculture systems (RAS), is a very important step, which aims to remove settleable and suspended solids, Postprint (published version)

The use of seaweed has increased notoriously since 1990's. Its main application is its utilization as a biofilter, since it has a great ability to capture nutrients from water, being useful in the treatment of effluents from aquaculture facilities and offering the possibility integrating its culture in recirculated systems. Moreover, they add an additional value to the aquaculture as a by-product, since it has a wide range of uses. The hydrodynamics of different models of tanks was analyzed. Two of them have a system that operates by water flow input, generating a inlet impulse force on a curved surface which keeps in suspension and in a rotational movement. This fact enhances the ability of seaweed to absorb radiation from the surface. The third model operates with an aeration system which injects an air flow from the bottom of the tank generating the same effect. The relationship between the inlet force exerted by the water inlet jet and the rotational speed of the algae biomass were taken into account, and also the relationship between the minimal forces needed to start the seaweed rotation and the amount of biomass. A comparison of the behavior of two species of Ulva, Ulva ohnoi and Ulva fasciata, having different morphologies was performed. Significant differences in the distribution of biomass in the tank were observed. Ulva ohnoi, a free laminar morphology, which was distributed more evenly using more efficiently the available radiation on the surface. Ulva fasciata was cultured for 10 weeks in an aeration tank to determine the evolution of the biomass at different parameters, and thus estimate its possible use in a recirculated system in aquaculture, since it hasn't been used in IMTA system yet., L'ús de les macroalgues a l'última dècada s'ha incrementat de manera notòria. La seva principal aplicació passa per la utilització d'aquestes com a biofiltres, que han demostrat la seva eficàcia en l'extracció de nutrients de l'aigua, convertint-se en un instrument molt important en el tractament d'efluents d'instal·lacions aqüícoles i amb la possibilitat d'integrar el seu cultiu a sistemes de recirculació. A més, ofereixen un valor afegit a la aqüicultura com a subproducte d'aquesta, ja que presenten un gran ventall d'usos. En el desenvolupament d'aquest projecte es varen analitzar les característiques hidrodinàmiques de tres models de tanc diferents. Dos d'ells, presenten un sistema que funciona mitjançant l'entrada d'un cabal d'aigua que genera una força d'impuls sobre una superfície corba i que permet mantenir en suspensió i en un moviment de rotació les macroalgues en cultiu, de manera que puguin aprofitar la radiació disponible a la superfície. El tercer model, funciona mitjançant un cabal d'aire injectat des de la part inferior del tanc que acaba generant el mateix efecte. Es van tenir en compte, per a la realització de l'anàlisi hidrodinàmic, la relació entre la força d'entrada d'aigua o aire i la velocitat de rotació; y la relació entre les forces mínimes necessàries per iniciar i mantenir en rotació la concentració de biomassa al tanc. Es va realitzar una comparació del comportament de diferents espècies de Ulva, Ulva ohnoi i Ulva fasciata, que presenten diferents morfologies. Es van observar diferencies importants en la distribució de la biomassa en el tanc. Ulva ohnoi, amb una morfologia laminar lliure, sense tal·lus, va ser la que es va distribuir de manera més uniforme, aprofitant així de manera més eficient la radiació disponible a la superfície. També es va realitzar un cultiu d'Ulva fasciata durant 10 setmanes en un tanc d'airejament per a multiplicar la seva biomassa i determinar la seva evolució davant diferents paràmetres de cultiu, podent així e, El uso de las macroalgas en las últimas décadas se ha acrecentado de una manera más que notoria. Su principal aplicación pasa por la utilización de éstas como biofiltros, que ha demostrado con creces su eficacia en la retirada de nutrientes del agua, siendo de utilidad en el tratamiento de efluentes de instalaciones acuícolas y con la posibilidad de integrar su cultivo en sistemas de recirculación. Pero además, ofrecen un valor añadido a la acuicultura como subproducto de ésta, ya que presentan un amplio abanico de usos. En el desarrollo de este proyecto se analizaron las características hidrodinámicas de tres modelos de tanques diferentes. Dos de ellos presentan un sistema que funciona mediante la entrada de un caudal de agua que genera una fuerza impulso sobre una superficie curva y que permite mantener en suspensión y en un movimiento de rotación las macroalgas en cultivo, de manera que puedan aprovechar la radiación disponible en la superficie. El tercero funciona mediante un caudal de aire inyectado desde la parte inferior del tanque generando el mismo efecto. Se tuvieron en cuenta para el análisis: la relación entre el flujo de entrada de agua o de aire y la velocidad de rotación alcanzada por la biomasa, la relación entre la potencia necesaria para iniciar y mantener en rotación las algas, y la concentración de biomasa. Se realizó una comparación del comportamiento de dos especies de Ulva, Ulva ohnoi y Ulva fasciata, que presentan diferentes morfologías. Se observaron diferencias importantes en la distribución de la biomasa en el tanque, siendo Ulva ohnoi con una morfología laminar libre, sin talo, la que se distribuyó de manera más uniforme, aprovechando de manera más eficiente la radiación disponible en la superficie. También se llevó a cabo un cultivo de Ulva fasciata durante 10 semanas en un tanque de aireación para determinar la evolución de la biomasa a diferentes parámetros de cultivo y estimar así la viabilidad de su posible utilización en sistemas de

The objective of this paper is characterize hidrodynamically a multivortex tank, with and without fish, in order to evaluate the effect of fish in the distribution and uniformity of the velocities in the tank. To conduct the study, a multivortex tank with a baffle placed between two consecutive water inlets was used. To measure the velocities, an acoustic velocimeter with a Doppler effect was used. To perform the experiment, different impulse forces, flow rates (300 l/hr and 200 l/hr for vortex) and water inlet diameters (20 mm and 13 mm) were used. This experiment was repeated for both with and without fish (sea bass) configurations. The following results were With or without Fish obtained: Velocity increases when impulse forces increase. This confirms that velocity is proportional to the square root of the impulsion forces. The uniformity of velocity increases when the inlet flow rate increases. With Fish in the tank generate turbulence through their movement, which leads to a decrease in average velocity and uniformity of velocity in the tank. For further research in this subject, one could perform variations of fish species or densities., L'objectiu del treball és caracteritzar hidrodinàmicament un tanc multivòrtex, amb i sense peixos, per tal de poder avaluar l'efecte dels peixos en la distribució de les velocitats de l'aigua al tanc i la seva uniformitat. Per realitzar l'estudi s'ha utilitzat un tanc multivòrtex amb un deflector col·locat entre dues entrades consecutives d'aigua. Per a la mesura de les velocitats s'ha emprat un velocímetre acústic d'efecte Doppler. Per efectuar els experiments es van utilitzar diferents forces d'impulsió, variant els cabals (300 i 200 l/h pe vòrtex) i diàmetres de les entrades d'aigua (20 i 13 mm). Aquests mateixos experiments s'han executat amb i sense peixos (llobarros). Els principals resultats obtinguts amb o sense peixos són: La velocitat augmenta quan augmenta la força d'impuls. En aquest estudi s'ha corroborat que les velocitats són proporcionals a l'arrel quadrada de la força d'impuls. Les uniformitats de les velocitats augmenten quan augmenta el cabal d'entrada. Amb peixos tant les velocitats mitges com la uniformitat de les velocitats disminueixen quan al tanc hi ha peixos, degut a la turbulència creada pel moviment dels mateixos peixos. Per seguir estudiant sobre la matèria és podrien realitzar variacions amb l'espècie o variar la densitat de peixos utilitzada., El objetivo del trabajo es caracterizar hidrodinámicamente un tanque multivórtice, con y sin peces, para poder evaluar el efecto de los peces en las distribuciones de las velocidades del agua al tanque y su uniformidad. Para realizar el estudio se ha utilizado un tanque multivórtice con un deflector colocado entre dos entradas consecutivas de agua. Para la medida de las velocidades se ha utilizado un velocímetro de efecto Doppler. Para elaborar los experimentos se utilizaron diferentes fuerzas de impulsión, variando los caudales (300 y 200 l/h por vórtice) y diámetros de entradas de agua (20 y 13 mm). Estos mismos experimentos se han ejecutado con y sin peces (Lubinas). Los principales resultados obtenidos tanto con cómo sin peces son: La velocidad aumenta cuando aumenta la fuerza de impulsión. En este estudio se ha comprobado que las velocidades son proporcionales a la raíz cuadrada de la fuerza de impulsión. Las uniformidades de las velocidades aumentan cuando aumenta el caudal de entrada. Con peces tanto las velocidades medias como la uniformidad de las velocidades disminuyen cuando el tanque tienen peces debido a la turbulencia generada por el movimiento de los mismos peces. Para seguir estudiando sobre la materia se podrían realizar variaciones de la especie o variar las densidades de peces utilizadas.

Quick removal of biosolids in aquaculture facilities, and specially in recirculating aquaculture systems (RAS), is one of the most important step in waste management . Sedimentation dynamics of biosolids in an aquaculture tank will determine their accumulation at the bottom of the tank ., Postprint (published version)

In sole (Solea spp.) culture, like in other flatfish culture, it is likely that a vertical gradient of dissolved oxygen (DO) occurs with the lower concentrations being at the tank bottom. This lower concentration at the tank bottom is a consequence of fish oxygen consumption and of the presence of the boundary layer. This fact generates lower DO concentrations in the near-bottom zone where soles are lying most of the time. The aim of this work was to study the hydrodynamic conditions that determine the oxygen gradient that occurs in the layer of water adjacent to flatfish.; Three flow rates were tested in a circular tank and in a rectangular or raceway tank. For each flow rate, water velocities, boundary layer thickness and Reynolds number were calculated. Results showed that the vertical gradient of dissolved oxygen diminishes when water velocity and Reynolds numbers (Re) increase. At the fish density used in this work (11.6 kg m(-2)), when Re decreased under 6000, a large increase in the DO gradient was observed. Guidelines are presented to determine in which situations, as defined by hydraulic parameters, Re >6000 is achieved and DO stratification avoided.; The present work shows that in raceways, the flow rate required to avoid DO stratification is higher than that typically needed to maintain water quality (oxygen, ammonia-nitrogen, carbon dioxide and suspended solids). In circular tanks, it can be easier to achieve velocities that are high enough to avoid stratification with low water inlet flow rates, by adjusting the area of the water entry orifices. (C) 2014 Elsevier B.V. All rights reserved., This work was funded by the Spanish Government (AGL2009-1655 and AGL2013-41868-R)., Postprint (published version)

The superior hydrodynamics of circular tanks over rectangular tanks are well known by aquaculturists; yet rectangular tanks are still widely used because of their easier handling. As a consequence, several studies have focused on the hydrodynamics of rectangular tanks, where rotating flow cells are generated by injecting water tangentially to the tank wall with the outlet placed in the center of the cell. In the present work, we evaluate the hydrodynamics in a rectangular tank with 4 rotating flow cells of 1m diameter, which is called multivortex tank. We also analyze baffle placement between two consecutive water inlets and the characteristics of the water inlet (flow rate and inlet velocity), which then allows us to determine the average velocities and the distribution uniformity of these velocities. The obtained results are compared with a circular tank having the same cell diameter and inlet configurations as the multivortex tank. Baffle placement between two consecutive water inlets in the multivortex tank helps increase the average velocity, the uniformity of velocities and the symmetry in the rotating flow cells. In configurations without baffles, the combination of low flow rate and high impulse force present the lowest symmetry. Differences between intermediate and extreme cells were observed. In all configurations tested, velocities and uniformities were higher in extreme cells than in intermediate cells. In the circular tank the average velocities achieved were higher than in the multivortex tank with the same impulse force, but the uniformity of velocities were higher in the multivortex tank. Finally, the proportionality between the average velocity and the square root of the impulse force for a specific tank geometry has been corroborated in commercial scale models., Postprint (published version)

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Los biofiltros con algas han demostrado su utilidad en el tratamiento de los efluentes de tanques de cultivo de peces y pueden ser integrados en sistemas de recirculación acuícola. La mayoría de los sistemas de cultivo de macroalgas utilizan aireación inferior para agitar y mantener las algas en suspensión, a la vez que la entrada de agua rica en nutrientes pasa a través de ellos. La turbulencia generada por la aireación también adelgaza la capa límite de las macroalgas, acelerando el flujo de intercambio de nutrientes. Se ha diseñado un nuevo tanque para lograr la rotación de la biomasa de macroalgas marinas mediante la proyección de los chorros de entrada de agua a una superficie curva colocada en la parte inferior del tanque. La biomasa de algas gira alrededor de un eje horizontal, lo que permite una exposición óptima a la luz y la formación de la turbulencia necesaria para disminuir la capa límite, sin utilizar aireación. Este diseño permite la utilización de la alta concentración de dióxido de carbono proveniente de la respiración de los peces, y un menor consumo de energía. Se analizaron las características hidrodinámicas del tanque, incluyendo: 1) la relación entre la fuerza ejercida por el chorro de entrada de agua y la velocidad de rotación alcanzada por la biomasa de algas, 2) la relación entre las fuerzas mínimas necesarias para iniciar la rotación de algas y la cantidad de la biomasa. Después de iniciarse la rotación, la velocidad alcanzada por la biomasa de algas fue proporcional a la raíz de la fuerza de impulsión. Sin embargo, cuando se sobrepasa un límite superior, se logra la velocidad de rotación máxima, y más aumentos en la fuerza de impulsión no contribuyen a aumentar la velocidad de rotación de las macroalgas. Se llevaron a cabo algunos experimentos de crecimiento con Ulva ohnoi en el diseño de tranque no aireado y en un tanque aireado similar. No se encontraron diferencias significativas al comparar los coeficientes medidos de crecimiento en am

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Descripció del recurs: 6 de març de 2014, Referències bibliogràfiques. Índex

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Peer Reviewed, Postprint (published version)

Projecte presentat al 3r Premi a la Qualitat de la Gestió Universitària, convocat pel Consell Social de la UPC, Award-winning

Conferència inagural: "La Teledetección del Siglo XXI en Agricultura: una nueva era basada en microsensores multiespectrales y vehículos aéreos no tripulados" a càrrec de Pablo Zarco-Tejada

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Evaluating flatfish activity can be a useful tool for studying fish behavior and welfare. The aim of this workwas to obtain a quantitative index for measuring flatfish activity using image analysis. Accordingly, motor activity of a sole population was recorded by digital video for three nights, bearing in mind the nocturnal lifestyle of the species. Subsequent image analysis was done by image subtraction of consecutive frames. The result was a ‘‘difference frame’’ showing the changes in the image area due to fish movement. Using these data, an image processing activity index (IPAI) was determined by measuring the percentage of area altered due to fish movement and by taking this percentage as an indicator of fish activity. Typical sole behavioral acts (take-off and surface swimming) were recorded by direct observation during the same intervals in order to calibrate the IPAI. A direct observation activity index (DOAI) was determined by weighting each kind of attitude according to its average duration. Results obtained from image analysis (IPAI) were compared with results obtained by direct observation (DOAI). A linear relationship between the two indexes was found with a correlation coefficient of r2 = 0.80 for 92% of coverage area tank and r2 = 0.90 for 210% of coverage area tank. Thus, this digital video-based index can be a highly reliable and accuratemethod for objectivelymeasuring activity levels in sole with a low consumption of labor and time. Nevertheless, the application to farm conditions would need further research and an accurate calibration for other species., Postprint (published version)

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