Optimization of nitrifying biofilters for aquaculture

[ES] Los sistemas de recirculación en acuicultura (definidos como circuitos cerrados con mínimo o nulo intercambio del agua de cría) son unos sistemas de producción acuícola con mucho potencial, pero requieren conocimientos específicos de los equipos de purificación de agua. La optimización de uno de estos equipos, el biofiltro nitrificante eliminador de nitrógeno amoniacal, es el objetivo de la presente tesis. Para ello se realizó una serie de experimentos donde se evaluó el rendimiento de biofiltros nitrificantes de percolación (expresado como tasa de eliminación amoniacal pero también prestando atención a la concentración de amonio máxima y mínima en el tanque) en función de diferentes características como son la carga de amonio en el influente del biofiltro, el tipo de material filtrante, la temperatura y la carga hidráulica. La combinación de parámetros (material filtrante, carga hidráulica y temperatura) que originó el mejor rendimiento del biofiltro fue seleccionada para diseñar los biofiltros usados en un experimento de cría de doradas (Sparus aurata) (especie seleccionada puesto que su rango de temperatura óptimo es equivalente a las temperaturas que originaron una mayor tasa de eliminación de amonio) en las mismas instalaciones. Durante este experimento, se reevaluó el rendimiento del biofiltro, sujeto a la influencia de la materia orgánica. Los peces fueron alimentados con tres piensos diferentes (un control, uno formulado a base de harina de pescado y uno formulado sin harina de pescado) y el pienso fue suministrado mediante tres estrategias diferentes de alimentación (a saciedad, utilizando comederos automáticos y utilizando comederos de auto-demanda). De la primera serie de experimentos se concluyó que, de los materiales filtrantes probados, uno de ellos (MECHpro® rings) fue responsable de rendimientos muy inferiores mientras que el uso de los materiales filtrantes restantes provocó un rendimiento muy similar. También se concluyó que la temperatura tuvo un efecto muy importante, pues bajas temperaturas (entre 15 y 18 ºC) originaron rendimientos bajos para cualquier combinación restante de parámetros por inactivación de las bacterias nitrificantes, mientras que a temperaturas altas el efecto de los diferentes parámetros, como la carga hidráulica, fue más significativo. Respecto a esta última, se observó un rendimiento claramente inferior a una carga hidráulica baja (4 m3/m2 h), así como rendimientos similares para las cargas hidráulicas restantes (8 m3/m2 h y 11 m3/m2 h). Una mayor carga de amonio produjo en todos los resultados de la primera serie de experimentos un rendimiento mayor, pero también picos de concentración de amonio elevados en el agua de cría, lo cual cuestiona su conveniencia en el correcto funcionamiento de los sistemas. Las tasas de eliminación de amonio de los biofiltros nitrificantes durante su utilización para la cría de doradas fue generalmente menor que en las pruebas de determinación del efecto de diferentes configuraciones en el rendimiento de biofiltros. Esto fue atribuido a la presencia de materia orgánica, pero también a la menor carga de amonio ligada a unas excreciones de amonio total bajas. Se observó asimismo que el pienso vegetal implicó una pérdida de rendimiento y también se concluyó que una determinada estrategia de alimentación (utilización de comederos de auto-demanda) produjo rendimientos superiores respecto a las restantes estrategias, tanto en tasa de eliminación amoniacal como en concentración de amonio en agua. El valor máximo de concentración de amonio fue el más bajo de todos los experimentos realizados, incluyendo los resultados de las pruebas de evaluación del efecto los parámetros operacionales en la tasa de eliminación de amonio.[EN] Recirculating aquaculture systems (defined as closed circuits where rearing water exchange is reduced to a minimum) show a great potential for fish production but require expertise of water purification equipment. The optimization of one of those units, the nitrifying biofilter, which removes ammonia nitrogen, is the subject of the present thesis. The performance (determined as ammonia removal rate but also taking into account the maximum and minimum concentration of N-TAN in the tank water) of a determinate type of these biofilters, the trickling filter, was evaluated according to different characteristics known as process parameters, such as the biofilter influent ammonia load, filter medium type, water temperature or hydraulic loading. The combination of those process parameters that led to the best results in biofilter performance was used to design biofilters for use in a pilot-scale rearing trial of gilthead sea bream (Sparus aurata), whose optimal growth temperature range is equivalent to the temperatures which led to the highest mean ammonia removal rate. During that experiment, carried out on the same facilities as the performance trials, the performance of the biofilter was re-evaluated, now subject to the influence of organic matter. Fish were fed three different diets (a control, a formulated diet with fishmeal and a formulated diet without fishmeal) y the feed was supplied by three different feeding strategies (to satiation, using automatic feeders and using auto-demand feeders). The first batch of experiments showed that, from the filter media assessed, one of them (MECHpro® rings) was responsible of low performance in general, while the ammonia removal rates were comparable with the use of the remaining filter media. It was also concluded that the temperature had a very important effect as low temperatures (between 15 and 18ºC) led to low ammonia removal independent of every combination of the remaining process parameters due to the inactivation of nitrifying bacteria, while the effect of other process parameters, such as the hydraulic loading, was more significant at high temperatures. In regard to this parameter, an inferior efficiency was observed at a low hydraulic loading (4 m3/m2 h) compared to the remaining hydraulic loadings (8 m3/m2 h y 11 m3/m2 h), although both values led to similar efficiencies. A higher ammonia load led to greater ammonia removal rates but also to high ammonia concentration peaks in the rearing water, which questions its convenience in the system correct operation. The mean ammonia removal rate of the nitrifying biofilters during operation in the gilthead sea bream rearing trial was generally lower than in the trials regarding the effect of the combination of process parameters on biofilter performance. This was attributed to the presence of organic matter, but also to the lower ammonia load consequence of low total ammonia excretion. In addition, it was observed that the plant meal based diet led to a loss of performance and that a determinate feeding strategy (use of auto-demand feeders) led to higher biofilter performances compared to the remaining feeding strategies, both in ammonia removal rate and in N-TAN concentration in the tank water. The maximum N-TAN concentration was the lowest across every experiment, including the results of the trials regarding the effect of the combination of process parameters on biofilter performance.[CA] Els sistemes de recirculació en aqüicultura (definits com circuits tancats amb un intercanvi mínim o nul) són uns sistemes de producció aqüícola amb molt de potencial, però requerixen coneixements específics dels equips de filtració de l'aigua. La optimització d'un d'aquests equips, els biofiltres nitrificants, encarregat de la eliminació de nitrogen amoniacal, es l'objectiu de la present tesi. Per a tal funció es va elaborar una sèrie d'experiments on es va avaluar el rendiment de biofiltres nitrificants de percolació (expressat com tassa d'eliminació amoniacal però tenint en compte la concentració d'amoni màxima i mínima) en funció de diferents característiques como són la carga d'amoni en l'influent del biofiltre, el tipus de material filtrant, la temperatura i la càrrega hidràulica. La combinació de paràmetres (material filtrant, temperatura i càrrega hidràulica) que va originar el major rendiment del biofiltre fou seleccionada per a dissenyar els biofiltres a utilitzar per a l'experiment de cria de dorades (Sparus aurata) en les mateixes instal·lacions, ja què el seu rang of temperatura òptim és coincident amb les temperatures que varen original la major taxa d'eliminació d'amoni. Durant aquest experiment, es va re-avaluar el rendiment del biofiltre, subjecte a la influència de la matèria orgànica. Els peixos varen ser alimentats amb tres pinsos diferents (un control, un formulat amb farina de peix i un formulat sense farina de peix) i el pinso va ser subministrat mitjançant tres estratègies d'alimentació (a sacietat, usant comeders automàtics i usant comeders d'auto-demanda. De la primera sèrie d'experiments es va concloure que, dels materials filtrants provats, un d'ells (MECHpro® rings) fou responsable de rendiments molt inferiors, mentre que l'ús dels restants materials filtrants va produir rendiments molt similars entre ells. També es va concloure que la temperatura va tindre un efecte molt important perquè baixes temperatures (entre 15 i 18 ºC) conduïren a baixos rendiments amb independència de la combinació dels altres paràmetres, degut a la inactivació de les bactèries nitrificants. Per una altra banda, amb altes temperatures, l'efecte de paràmetres com la càrrega hidràulica sobre les tasses d'eliminació d'amoni fou més significatiu. Respecte a aquesta última, es va observar un rendiment clarament inferior a una càrrega hidràulica baixa (4 m3/m2 h) respecte a les restants càrregues hidràuliques (8 m3/m2 h y 11 m3/m2 h) que varen originar similar rendiments entre elles. Una major càrrega d'amoni va produir en tots els resultats de la primera sèrie d'experiments un rendiment major, però també pics de concentració d'amoni elevats en l'aigua de cria, la qual cosa cuestiona la seua conveniència en el correcte funcionament dels sistemes. El rendiment dels biofiltres nitrificant durant la seua utilització per a la cria de dorades fou generalment menor que en les proves de determinació dels efectes de diferents configuracions en la taxa d'eliminació d'amoni. Això fou atribuït a la presència de matèria orgànica, però també a la menor càrrega d'amoni lligada a unes excrecions d'amoni total baixes. Es va observar tanmateix que el pinso vegetal va implicar una pèrdua de rendiment i també es va concloure que una determinada estratègia d'alimentació (utilització de comeders d'auto-demanda) va produir rendiments superiors respecte a les restants estratègies, tant en taxa d'eliminació amoniacal como en concentració d'amoni en l'aigua. El valor màxim de concentració d'amoni fou el mes baix de tots els experiments realitzats, incloent els resultats de les proves d'avaluació del efecte dels paràmetres operacionals en la taxa d'eliminació d'amoni.Godoy Olmos, S. (2020). Optimization of nitrifying biofilters for aquaculture [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/148718TESI

Influence of diet and feeding strategy on the performance of nitrifying trickling filter, oxygen consumption and ammonia excretion of gilthead sea bream (Sparus aurata) raised in recirculating aquaculture systems

[EN] Gilthead sea bream (Sparus aurata) was raised in six individual recirculating aquaculture systems (RAS) whose bioflters¿ performance was analyzed. Fish were fed with three diferent diets (a control diet, a fshmeal-based diet (FM), and a plant meal-based diet (VM)) and with three diferent feeding strategies (manual feeding to apparent satiation, automatic feeding with restricted ration, and auto-demand feeding). For every combination of diet and feeding strategy, the mean oxygen consumption, ammonia excretion, and ammonia removal rate were determined. Fish fed with the VM diet consumed the most oxygen (20.06±1.80 gO2 consumed kg¿1 day¿1). There were signifcant diferences in ammonia excretion depending on the protein content and protein efciency of the diet, as well as depending on feeding strategy, which in turn afected ammonia removal rates. Fish fed by auto-demand feeders led to the highest mean ammonia removal rate (0.10 gN-TAN removed m¿2 biofltration area day¿1), while not leading to peaks of high ammonia concentration in water, which preserve fsh welfare and growth.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Research is funded by the national project ¿Design of a recirculating aquaculture system for aquaculture plants (2011¿2014),¿ by the Ministry of Science and Innovation, Spain, as well as by a grant financed by Generalitat Valenciana, IDIFEDER/2020/029, and by the project ¿Recirculating aquaculture systems¿ by Universitat Politècnica de València. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Godoy-Olmos, S.; Jauralde García, I.; Monge-Ortiz, R.; Milián Sorribes, MC.; Jover Cerda, M.; Tomas-Vidal, A.; Martínez-Llorens, S. (2022). Influence of diet and feeding strategy on the performance of nitrifying trickling filter, oxygen consumption and ammonia excretion of gilthead sea bream (Sparus aurata) raised in recirculating aquaculture systems. Aquaculture International. 30(2):581-606. https://doi.org/10.1007/s10499-021-00821-358160630

Digestive tract morphology and enzyme activities of juvenile diploid and triploid Atlantic salmon (Salmo salar) fed fishmeal-based diets with or without fish protein hydrolysates

[EN] Triploid, sterile Atlantic salmon (Salmo salar) could make a contribution to the development of the farming industry, but uncertainties about the performance and welfare of triploids have limited their adoption by farmers. In this study, we compared the ontogeny of digestive tract morphology and enzyme activities (pepsin, trypsin, chymotrypsin, alkaline phosphatase and aminopeptidase) of diploid and triploid Atlantic salmon. Fish were fed diets based on fishmeal (STD) or a mix of fishmeal and hydrolysed fish proteins (HFM) whilst being reared at low temperature from start-feeding to completion of the parr-smolt transformation. Fish weights for each ploidy and feed combination were used to calculate thermal growth coefficients (TGCs) that spanned this developmental period, and the data were used to examine possible relationships between enzyme activities and growth. At the end of the experiment, faeces were collected and analyzed to determine the apparent digestibility coefficients (ADCs) of the dietary amino acids (AAs). Digestive tract histo-morphology did not differ substantially between ploidies and generally reflected organ maturation and functionality. There were no consistent differences in proteolytic enzyme activities resulting from the inclusion of HFM in the diet, nor was there improved digestibility and AA bioavailability of the HFM feed in either diploid or triploid fish. The triploid salmon had lower ADCs than diploids for most essential and non-essential AAs in both diets (STD and HFM), but without there being any indication of lower intestinal protease activity in triploid fish. When trypsin-to-chymotrypsin activity and trypsin and alkaline phosphatase (ALP) ratios (T:C and T:ALP, respectively) were considered in combination with growth data (TGC) low T:C and T:ALP values coincided with times of reduced fish growth, and vice versa, suggesting that T:C and T:ALP may be used to predict recent growth history and possible growth potential.This work was supported by the Norwegian Research Council, Regional Research Fund-RFF-NORD -https://www. regionaleforskningsfond.no/ -(Grant no. 248028, VP at Nofima as project coordinator) and the Norwegian College of Fishery Science, University of Tromsø, (UiT) the Arctic University of Norway. The funder provided support in the form of salary for one author [VP] but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of this and other authors are articulated in the "author contributions" section. Publication charges for the article were provided by the Open Access publication fund of UiT, the Arctic University of Norway.Martínez-Llorens, S.; Peruzzi, S.; Falk-Petersen, I.; Godoy-Olmos, S.; Olav Ulleberg, L.; Tomas-Vidal, A.; Puvanendran, V.... (2021). Digestive tract morphology and enzyme activities of juvenile diploid and triploid Atlantic salmon (Salmo salar) fed fishmeal-based diets with or without fish protein hydrolysates. PLoS ONE. 16(1):1-28. https://doi.org/10.1371/journal.pone.0245216S128161Benfey, T. J. (2015). Effectiveness of triploidy as a management tool for reproductive containment of farmed fish: Atlantic salmon (Salmo salar) as a case study. Reviews in Aquaculture, 8(3), 264-282. doi:10.1111/raq.12092Lijalad, M., & Powell, M. D. (2009). Effects of lower jaw deformity on swimming performance and recovery from exhaustive exercise in triploid and diploid Atlantic salmon Salmo salar L. Aquaculture, 290(1-2), 145-154. doi:10.1016/j.aquaculture.2009.01.039Benfey, T. 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Inclusion of alternative marine by-products in aquafeeds with different levels of plant-based sources for on-growing gilthead sea bream (Sparus aurata, L.): effects on digestibility, amino acid retention, ammonia excretion and enzyme activity

[EN] The search for new sustainable aquafeeds for the species with greater economic importance, such as the gilthead sea bream in Europe, is one of the main challenges in the aquaculture sector. The present work tested fishmeal replacement by a mixture of plant meals at different levels, as well as the use of marine by-products with attractant properties and high-quality protein in high plant protein diets. In order to do that, effects on growth and biometric parameters, digestibility, amino acid retention, excreted ammonia and proteases and amylase activity were assessed, using six different diets: FM100 (100% of protein provided by fishmeal), FM50 (50% of replacement), FM25 (75% of replacement) and FM0 (100% of replacement), but also FM25+ (75% of replacement and 15% of squid and krill meal inclusion), and FM0+ (100% of replacement and 15% of squid and krill meal inclusion). In group FM0, a clear impact of dietary changes was observed on growth, survival and ammonia excretion. Amino acid retention in group FM0+ was also significantly affected, which can be explained by the limited content of certain amino acids in this diet. On the other hand, no significant differences were observed in most biometric parameters or in enzyme activity. In conclusion, complete fishmeal replacement can be achieved by using a mixture of plant-based sources, but supplementation with complementary marine ingredients can prevent detrimental effects on growth, survival, nutritional parameters and protein metabolism.This work was supported by the Vicerrectorat d'Investigacio, Innovacio i Transferencia of the Universitat Politecnica de Valencia, within the project Aquaculture feed without fishmeal (SP20120603). URLs of funder: http://www.upv.es/entidades/VIIT/info/indexnormalc.htm. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Estruch-Cucarella, G.; Tomas-Vidal, A.; El Nokrashy, AM.; Monge-Ortiz, R.; Godoy-Olmos, S.; Jover Cerda, M.; Martínez-Llorens, S. (2018). Inclusion of alternative marine by-products in aquafeeds with different levels of plant-based sources for on-growing gilthead sea bream (Sparus aurata, L.): effects on digestibility, amino acid retention, ammonia excretion and enzyme activity. Archives of Animal Nutrition. 72(4):321-329. https://doi.org/10.1080/1745039X.2018.1472408S32132972

Inclusion of alternative marine by-products in aquafeeds with different levels of plant-based sources for on-growing gilthead sea bream (<i>Sparus aurata</i>, L.): effects on digestibility, amino acid retention, ammonia excretion and enzyme activity

<p>The search for new sustainable aquafeeds for the species with greater economic importance, such as the gilthead sea bream in Europe, is one of the main challenges in the aquaculture sector. The present work tested fishmeal replacement by a mixture of plant meals at different levels, as well as the use of marine by-products with attractant properties and high-quality protein in high plant protein diets. In order to do that, effects on growth and biometric parameters, digestibility, amino acid retention, excreted ammonia and proteases and amylase activity were assessed, using six different diets: FM100 (100% of protein provided by fishmeal), FM50 (50% of replacement), FM25 (75% of replacement) and FM0 (100% of replacement), but also FM25+ (75% of replacement and 15% of squid and krill meal inclusion), and FM0+ (100% of replacement and 15% of squid and krill meal inclusion). In group FM0, a clear impact of dietary changes was observed on growth, survival and ammonia excretion. Amino acid retention in group FM0+ was also significantly affected, which can be explained by the limited content of certain amino acids in this diet. On the other hand, no significant differences were observed in most biometric parameters or in enzyme activity. In conclusion, complete fishmeal replacement can be achieved by using a mixture of plant-based sources, but supplementation with complementary marine ingredients can prevent detrimental effects on growth, survival, nutritional parameters and protein metabolism.</p

Digestive tract morphology and enzyme activities of juvenile diploid and triploid Atlantic salmon (Salmo salar) fed fishmealbased diets with or without fish protein hydrolysates

Triploid, sterile Atlantic salmon (Salmo salar) could make a contribution to the development of the farming industry, but uncertainties about the performance and welfare of triploids have limited their adoption by farmers. In this study, we compared the ontogeny of digestive tract morphology and enzyme activities (pepsin, trypsin, chymotrypsin, alkaline phosphatase and aminopeptidase) of diploid and triploid Atlantic salmon. Fish were fed diets based on fishmeal (STD) or a mix of fishmeal and hydrolysed fish proteins (HFM) whilst being reared at low temperature from start-feeding to completion of the parr-smolt transformation. Fish weights for each ploidy and feed combination were used to calculate thermal growth coefficients (TGCs) that spanned this developmental period, and the data were used to examine possible relationships between enzyme activities and growth. At the end of the experiment, faeces were collected and analyzed to determine the apparent digestibility coefficients (ADCs) of the dietary amino acids (AAs). Digestive tract histo-morphology did not differ substantially between ploidies and generally reflected organ maturation and functionality. There were no consistent differences in proteolytic enzyme activities resulting from the inclusion of HFM in the diet, nor was there improved digestibility and AA bioavailability of the HFM feed in either diploid or triploid fish. The triploid salmon had lower ADCs than diploids for most essential and non-essential AAs in both diets (STD and HFM), but without there being any indication of lower intestinal protease activity in triploid fish. When trypsin-tochymotrypsin activity and trypsin and alkaline phosphatase (ALP) ratios (T:C and T:ALP, respectively) were considered in combination with growth data (TGC) low T:C and T:ALP values coincided with times of reduced fish growth, and vice versa, suggesting that T:C and T:ALP may be used to predict recent growth history and possible growth potential