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Due to the increasing number of ecosystem invasions with the introduction of exogenous species via ballast water, the International Maritime Organization adopted the Ballast Water Convention (BWMC). The BWMC establishes standards for the concentration of viable organisms in a ballast water discharge. Ultraviolet (UV) irradiation is commonly used for treating ballast water; however, regrowth after UV irradiation and other drawbacks have been reported. In this study, improvement in UV treatment with the addition of hydrogen peroxide or peroxymonosulfate salt was investigated using the microalgae Tetraselmis suecica as the target organism. Results reported that each of these reagents added in a concentration of 10 ppm reduced the concentration of initial cells by more than 96%, increased the UV inactivation rate, and enabled reaching greater level of inactivation with the treatment. These improvements imply a reduction of the UV doses required for a consistent compliance with the BWMC standards.

Tetraselmis suecica was cultivated in a semi-continuously operated tubular photobioreactor fed on aquaculture wastewater (AW) testing two hydraulic retention times (HRT): 10 and 7 days (RUN_1 and RUN_2, respectively). The integrated mechanistic model BIO_ALGAE was validated with experimental data in order to simulate the biomass production and nutrient uptake of T. suecica. Moreover, AW was used as substitute synthetic cultivation medium to test the production of lipids, proteins, and carbohydrates in the microalgal biomass. Preliminary photo-respirometric tests were carried out on the AW suspension containing microalgae and bacteria. Dissolved Inorganic Nitrogen (DIN) and Dissolved Inorganic Phosphorus (DIP) were analyzed for the two RUNs, and no significant difference was highlighted (p > 0.05). On the contrary, the productivity of the Total suspended solids (TSS) was significantly higher (p < 0.05) for RUN_1 (900 mg TSS/L) than for RUN_2 (550 mg TSS/L). The analysis of the biochemical composition of biomass has demonstrated a higher content of proteins than of lipids and carbohydrates for the two RUNs. BIO_ALGAE model was validated by comparing simulated results to experimental data. The model was able to reproduce the pattern of these experimental data quite well, for both nutrient uptake and biomass production. The simulated curve follows the same pattern as the experimental data for both RUNs. The wavelike trend indicates the good accuracy of the simulated curves to reproduce the microalgae growth and nutrient uptake that occurring during daytime and at night. With this study, BIO_ALGAE Model was demonstrated to be useful to simulate bioremediation and microalgae production in aquaculture wastewater in a semi-continuous system with different environmental factors. The photo-respirometric outputs were compared with the process rates affecting dissolved oxygen dynamics computed by the mathematical model., The authors would like to thank the Italian Ministry of University and Research (MIUR) and Fondazione Cariplo, for funding part of this research (“Vademecum” and “Il polo delle microalghe” projects) and Dr. Nadia Margariti for her valuable help in laboratory., Peer Reviewed, Postprint (author's final draft)

Tetraselmis suecica was cultivated in a semi-continuously operated tubular photobioreactor fed on aquaculture wastewater (AW) testing two hydraulic retention times (HRT): 10 and 7 days (RUN_1 and RUN_2, respectively). The integrated mechanistic model BIO_ALGAE was validated with experimental data in order to simulate the biomass production and nutrient uptake of T. suecica. Moreover, AW was used as substitute synthetic cultivation medium to test the production of lipids, proteins, and carbohydrates in the microalgal biomass. Preliminary photo-respirometric tests were carried out on the AW suspension containing microalgae and bacteria. Dissolved Inorganic Nitrogen (DIN) and Dissolved Inorganic Phosphorus (DIP) were analyzed for the two RUNs, and no significant difference was highlighted (p > 0.05). On the contrary, the productivity of the Total suspended solids (TSS) was significantly higher (p < 0.05) for RUN_1 (900 mg TSS/L) than for RUN_2 (550 mg TSS/L). The analysis of the biochemical composition of biomass has demonstrated a higher content of proteins than of lipids and carbohydrates for the two RUNs. BIO_ALGAE model was validated by comparing simulated results to experimental data. The model was able to reproduce the pattern of these experimental data quite well, for both nutrient uptake and biomass production. The simulated curve follows the same pattern as the experimental data for both RUNs. The wavelike trend indicates the good accuracy of the simulated curves to reproduce the microalgae growth and nutrient uptake that occurring during daytime and at night. With this study, BIO_ALGAE Model was demonstrated to be useful to simulate bioremediation and microalgae production in aquaculture wastewater in a semi-continuous system with different environmental factors. The photo-respirometric outputs were compared with the process rates affecting dissolved oxygen dynamics computed by the mathematical model.

Meeting the recent biological standards established by the Ballast Water Management Convention requires the application of ballast water treatment systems; ultraviolet irradiation is a frequently used option. However, organisms can repair the damage caused by ultraviolet irradiation primarily with photo-repair mechanisms that are dependent on the availability of light. The objective of this study is to quantify the impact of dark storage following ultraviolet irradiation on the viability of the microalgae Tetraselmis suecica. Results showed that one day of dark storage after ultraviolet irradiation enhanced the inactivation rate by 50% with respect to the absence of dark storage and increased up to the 84% with five days of dark storage. These results are consistent with photorepair, mostly in the first two days, prevented in the dark. The dose required to inactivate a determined ratio of organisms was correlated with the length of the dark post-treatment according to an inverse proportional function. This correlation may help to optimize the operation of ultraviolet ballast water treatment systems. Further, the results show that growth assays can detect organisms that are capable of repair after treatment with UV.

[Resumen] Debido a la creciente presencia de microcontaminantes emergentes en el medio marino, ha surgido la necesidad de estudiar la potencial toxicidad de estos compuestos sobre organismos acuáticos como las microalgas, utilizadas como indicadores de la contaminación debido a su papel fundamental como productores primarios. En este trabajo se propone una aproximación metodológica basada en el análisis citómico, para caracterizar las alteraciones producidas por distintos compuestos pertenecientes a las principales clases de fármacos y productos de cuidado e higiene personal, en la microalga marina Tetraselmis suecica, y establecer marcadores específicos de contaminación que sean sensibles y de respuesta rápida. Esta microalga verde es de crecimiento rápido, fácil de cultivar en laboratorio y muy utilizada en acuicultura como cultivo auxiliar. Todos los contaminantes emergentes ensayados, los antibióticos cloranfenicol, florfenicol y oxitetraciclina, el fármaco omeprazol, el filtro solar benzofenona‐3, el conservante triclosán y la fragancia tonalide, provocaron alteraciones fisiológicas en T. suecica. La autoflurescencia celular, la actividad esterasa y el potencial de membrana citoplasmático, han sido los parámetros más sensibles, mostrando alteraciones significativas en las células transcurridas sólo 24 h de exposición a los contaminantes, antes de poder detectar cambios en el crecimiento o viabilidad celular de los cultivos., [Resumo] Debido á crecente presenza de microcontaminantes emerxentes no medio mariño, xurdiu a necesidade de estudar a potencial toxicidade destes compostos sobre organismos acuáticos como as microalgas, utilizadas como indicadores da contaminación debido ao seu papel fundamental como produtores primarios. Neste traballo proponse unha aproximación metodolóxica baseada na análise citómica, para caracterizar as alteracións producidas por distintos compostos pertencentes ás principais clases de fármacos e produtos de coidado e hixiene persoal, na microalga mariña Tetraselmis suecica, e establecer marcadores específicos de contaminación que sexan sensibles e de resposta rápida. Esta microalga verde é de crecemento rápido, fácil de cultivar en laboratorio e moi utilizada en acuicultura como cultivo auxiliar. Todos os contaminantes emerxentes ensaiados, os antibióticos cloranfenicol, florfenicol e oxitetraciclina, o fármaco omeprazol, o filtro solar benzofenona‐3, o conservante triclosán e a fragrancia tonalide, provocaron alteracións fisiolóxicas en T. suecica. A autoflurescencia celular, a actividade esterasa e o potencial de membrana citoplasmático, foron os parámetros máis sensibles, mostrando alteracións significativas nas células transcorridas só 24 h de exposición aos contaminantes, antes de poder detectar cambios no crecemento ou viabilidade celular dos cultivos., [Abstract] Due to the growing presence of emerging micropollutants in the marine environment, the need to study the potential toxicity of these compounds on aquatic organisms such as microalgae has arisen. These microorganisms are used as indicators of pollution due to their fundamental role as primary producers. This study suggest a methodological approach based on the cytometric analysis, to characterize the alterations produced by different compounds belonging to the main classes of pharmaceuticals and personal care products, on the marine microalga Tetraselmis suecica, and to establish sensitive and fast specific markers of pollution. This green microalga is fast‐growing, easy to culture in the laboratory and widely used in aquaculture as auxiliary culture. All the assayed emerging pollutants, the antibiotics chloramphenicol, florphenicol and oxytetracycline, the pharmaceutical omeprazole, the ultraviolet filter benzophenone‐3, the disinfectant triclosan and the fragrance tonalide, caused physiological alterations in T. suecica. Cell autofluorescence, esterase activity and cytoplasmic membrane potential were the most sensitive parameters, showing significant alterations in the cells after only 24 h of exposure to the pollutants, before being able to detect changes in cell growth or viability of the cultures.

Actualmente, la larvicultura marina depende del uso de presas vivas enriquecidas como Artemia para cubrir totalmente los requerimientos nutricionales de las primeras fases de desarrollo de las especies marinas acuícolas. El enriquecimiento, que consiste en poner en contacto a los individuos con un compuesto rico en ácidos grasos esenciales altamente insaturados (HUFAs), presenta una eficiencia limitada debido a la autooxidación de éstos por parte de Artemia. En este estudio, en primer lugar, se compararon Tetraselmis suecica e Isochrysis galbana para determinar la concentración óptima de microalgas como alimento durante el cultivo de A. franciscana (AF) hasta los 6 días de edad, mediante el crecimiento, supervivencia y comportamiento alimenticio, evaluado con la tasa de filtración e ingestión, en función de la concentración de microalgas en el medio. En segundo lugar, se analizó el efecto beneficioso o protector del uso de un antioxidante rico en polifenoles durante el enriquecimiento de metanauplios de AF de 3 días de edad, mediante la evaluación de la actividad CAT y la peroxidación lipídica como biomarcadores de estrés oxidativo. Los resultados demostraron que los metanauplios de AF crecen más cuando se utiliza T. suecica como alimento, y la talla a los 3 y 6 días de edad aumenta con la concentración de microalgas. Por otra parte, los resultados de los metanauplios enriquecidos con LC60 junto con un antioxidante presentaron menor actividad CAT, lo que sugiere que este uso combinado tiene un efecto protector frente al estrés oxidativo ocasionado durante el enriquecimiento con sustancias prooxidantes ricas en HUFAs

[Resumen] Debido a la creciente presencia de microcontaminantes emergentes en el medio marino, ha surgido la necesidad de estudiar la potencial toxicidad de estos compuestos sobre organismos acuáticos como las microalgas, utilizadas como indicadores de la contaminación debido a su papel fundamental como productores primarios. En este trabajo se propone una aproximación metodológica basada en el análisis citómico, para caracterizar las alteraciones producidas por distintos compuestos pertenecientes a las principales clases de fármacos y productos de cuidado e higiene personal, en la microalga marina Tetraselmis suecica, y establecer marcadores específicos de contaminación que sean sensibles y de respuesta rápida. Esta microalga verde es de crecimiento rápido, fácil de cultivar en laboratorio y muy utilizada en acuicultura como cultivo auxiliar. Todos los contaminantes emergentes ensayados, los antibióticos cloranfenicol, florfenicol y oxitetraciclina, el fármaco omeprazol, el filtro solar benzofenona‐3, el conservante triclosán y la fragancia tonalide, provocaron alteraciones fisiológicas en T. suecica. La autoflurescencia celular, la actividad esterasa y el potencial de membrana citoplasmático, han sido los parámetros más sensibles, mostrando alteraciones significativas en las células transcurridas sólo 24 h de exposición a los contaminantes, antes de poder detectar cambios en el crecimiento o viabilidad celular de los cultivos., [Resumo] Debido á crecente presenza de microcontaminantes emerxentes no medio mariño, xurdiu a necesidade de estudar a potencial toxicidade destes compostos sobre organismos acuáticos como as microalgas, utilizadas como indicadores da contaminación debido ao seu papel fundamental como produtores primarios. Neste traballo proponse unha aproximación metodolóxica baseada na análise citómica, para caracterizar as alteracións producidas por distintos compostos pertencentes ás principais clases de fármacos e produtos de coidado e hixiene persoal, na microalga mariña Tetraselmis suecica, e establecer marcadores específicos de contaminación que sexan sensibles e de resposta rápida. Esta microalga verde é de crecemento rápido, fácil de cultivar en laboratorio e moi utilizada en acuicultura como cultivo auxiliar. Todos os contaminantes emerxentes ensaiados, os antibióticos cloranfenicol, florfenicol e oxitetraciclina, o fármaco omeprazol, o filtro solar benzofenona‐3, o conservante triclosán e a fragrancia tonalide, provocaron alteracións fisiolóxicas en T. suecica. A autoflurescencia celular, a actividade esterasa e o potencial de membrana citoplasmático, foron os parámetros máis sensibles, mostrando alteracións significativas nas células transcorridas só 24 h de exposición aos contaminantes, antes de poder detectar cambios no crecemento ou viabilidade celular dos cultivos., [Abstract] Due to the growing presence of emerging micropollutants in the marine environment, the need to study the potential toxicity of these compounds on aquatic organisms such as microalgae has arisen. These microorganisms are used as indicators of pollution due to their fundamental role as primary producers. This study suggest a methodological approach based on the cytometric analysis, to characterize the alterations produced by different compounds belonging to the main classes of pharmaceuticals and personal care products, on the marine microalga Tetraselmis suecica, and to establish sensitive and fast specific markers of pollution. This green microalga is fast‐growing, easy to culture in the laboratory and widely used in aquaculture as auxiliary culture. All the assayed emerging pollutants, the antibiotics chloramphenicol, florphenicol and oxytetracycline, the pharmaceutical omeprazole, the ultraviolet filter benzophenone‐3, the disinfectant triclosan and the fragrance tonalide, caused physiological alterations in T. suecica. Cell autofluorescence, esterase activity and cytoplasmic membrane potential were the most sensitive parameters, showing significant alterations in the cells after only 24 h of exposure to the pollutants, before being able to detect changes in cell growth or viability of the cultures.

[Resumen]: En los últimos años, el desarrollo de nuevos y más sensibles métodos analíticos ha permitido alertar de la presencia de contaminantes emergentes en aguas. Su impacto lleva a cabo cambios en la composición de individuos de la comunidad acuática, cambios en los organismos dominantes de un hábitat y empobrecimiento de especies. Muchos de estos contaminantes son disruptores endocrinos, como el bisfenol A (BPA). Las microalgas juegan un papel fundamental para el equilibrio del ecosistema acuático y son un buen indicador de toxicidad del medio. En el presente trabajo se estudia el posible efecto tóxico que ejerce el bisfenol A en Tetraselmis suecica. Se realizaron cultivos de esta microalga a diferentes concentraciones de BPA (3, 4, 5 y 6 mg l-1) durante 72 h y a dos temperaturas (18 y 22 ºC) respectivamente. Además se determinó el contenido celular de pigmentos (clorofila a y b y carotenoides). El crecimiento celular y la cantidad de pigmentos muestran diferencias en los cultivos expuestos a BPA y también varían dependiendo de las temperaturas en las que se cultive. Por esto, se puede determinar que T.suecica es sensible a la toxicidad del BPA y el aumento de temperatura influye negativamente. Debido a los parámetros analizados se deduce que T. suecica sería un buen indicador de calidad ambiental., [Resumo]: Nos últimos anos, o desenrolo de novos e máis sensibles métodos analíticos permitiu alertar da presenza de contaminantes emerxentes nas augas. O seu impacto leva a cabo cambios na composición dos individuos da comunidade acuática, cambios nos organismos dominantes dun hábitat e empobrecemento de especies. Moitos de istes contaminantes son disruptores endocrinos, como o bisfenol A (BPA). As microalgas xogan un papel fundamental para o equilibrio do ecosistema acuático e son un bo indicador de toxicidade do medio. No presente traballo estudiase o posible efecto toxico que exerce o bisfenol A en Tetraselmis suecica. Realizaronse cultivos desta microalga a diferentes concentracións de BPA (3, 4, 5 y 6 mg l-1) durante 72 h e a duas temperaturas (18 e 5 22 ºC) respectivamente. Ademáis, determinouse o contido celular e de pigmentos (clorofila a y b y carotenoides). O crecemento celular e a cantidade de pigmentos mostran diferencias nos cultivos expostos o BPA e tamén varían dependendo das temperaturas nas que se cultive. Por iso, pódese determinar que T. suecica é sensible a toxicidade do BPA e o aumento da temperatura influe negativamente. Debido os parámetros analizados dedúcese que T.suecica é bo indicador de calidade ambiental., [Abstract]: In recent years, the development of new and more sensitive analytical methods has made it possible to alert the presence of emerging contaminants in water. Their impact has caused changes in the composition of individuals in the aquatic community, changes in the dominant organisms of a habitat and impoverishment of species. Many of these pollutants are endocrine disrupters, such as Bisphenol A (BPA). Microalgae play a fundamental role in the equilibrium of the aquatic ecosystem and are a good indicator of medium toxicity. In this paper we study the possible toxic effect exerted by bisphenol A in Tetraselmis suecica. Cultives of these microalgae were carried out at different concentrations of BPA (3, 4, 5 and 6 mg L-1) during 72 h and at two temperatures (18 and 22 º C) respectively. In addition, the cellular content of pigments (chlorophyll a and b and carotenoids) was determined. Cell growth and the amount of pigments show differences in crops exposed to BPA and also vary depending on the temperatures in which they are cultivated. Therefore, it can be determined that T. suecica is sensitive to the toxicity of BPA and that increase in temperature influences negatively. Due to the analyzed parameters, the fact that T. suecica would be a good indicator of environmental quality.

[Resumen] Los contaminantes emergentes, entre los que se encuentran los productos de higiene personal, suponen un riesgo ambiental en los ecosistemas acuáticos, debido al potente efecto negativo que pueden provocar sobre la biota allí presente, sobre todo en las microalgas por ser los principales productores primarios en estos ambientes, con la consecuente importancia que ello supone en la cadena trófica. En el caso concreto del triclosán, su presencia ya se ha detectado en ecosistemas acuáticos de todo el mundo, incluyendo Galicia. Por otra parte, la emisión de gases de efecto invernadero hacia la atmósfera está provocando un aumento de la temperatura media del planeta. Este aumento de la temperatura, debido al cambio climático, puede ocasionar alteraciones en las actividades metabólicas normales de los organismos. En el presente trabajo, se analiza el efecto negativo del triclosán y del aumento de la temperatura en la microalga marina Tetraselmis suecica a través del estudio del crecimiento, contenido en pigmentos, actividad celular y peroxidación lipídica de la misma. La exposición a triclosán durante un período de 72 horas provocó un descenso significativo (p < 0,05) del crecimiento, del contenido de pigmentos y de la actividad celular, sin embargo, sólo se obtuvieron diferencias significativas a las 24 horas en la peroxidación lipídica. En cuanto a la temperatura, se obtuvieron diferencias significativas (p < 0,05) para el contenido de pigmentos, tanto de clorofila a como de carotenos, mostrando además interacción significativa (p < 0,05) entre el aumento de la temperatura y la presencia de triclosán., [Resumo] Os contaminantes emerxentes, entre os que se encontran os produtos de hixiene persoal, supoñen un risco ambiental nos ecosistemas acuáticos, debido ao potente efecto negativo que poden provocar sobre a biota alí presente, sobre todo nas microalgas por ser os principais produtores primarios nestos ambientes, coa consecuente importancia que eso supón na cadea trófica. No caso concreto do triclosán, xa se teñen detectado cantidades de dito contaminante nos ecosistemas acuáticos de todo o mundo, incluíndo Galicia. Por outra banda, a emisión de gases de efecto invernadeiro hacia a atmosfera está provocando un aumento da temperatura media do planeta. Este aumento da temperatura, debido ao cambio climático, pode ocasionar alteracións nas actividades metabólicas normais dos organismos. No presente traballo, analízase o efecto negativo do triclosán e dun aumento da temperatura na microalga mariña Tetraselmis suecica a través do estudo do crecemento, contido en pigmentos, actividade celular e peroxidación lipídica da mesma. A exposición de triclosán durante un periodo de 72 horas provocou un descenso significativo (p < 0,05) do crecemento, do contido de pigmentos e da actividade celular, porén, non se obtiveron diferencias significativas en canto a peroxidación lipídica. En canto a temperatura, obtivéronse datos significativos (p < 0,05) para o contido de pigmentos e actividade celular, mostrando ademáis interacción significativa (p < 0,05) entre o aumento de temperatura e a presenza de triclosán., [Abstract] Emerging pollutants, including personal care products, pose an environmental risk in aquatic ecosystems, due to the potent negative effect they can cause on the biota present there, especially in microalgae as the main primary producers in these environments, with the consequent importance that this supposes in the trophic chain. In the specific case of triclosan, its presence has already been detected in aquatic ecosystems around the world, also in Galicia. On the other hand, the emission of greenhouse gases towards the atmosphere is causing an increase of the average temperature of the planet. This increase in temperature, due to climate change, can cause alterations in the normal metabolic activities of organisms. In the present work, the negative effect of triclosan and temperature increase on the Tetraselmis suecica marine microalga are analyzed through the study of growth, pigment content, cellular activity and lipid peroxidation. Exposure to triclosan over a period of 72 hours resulted in a significant (p < 0.05) decrease in growth, pigment content and cellular activity, however, only significant differences were obtained at 24 hours in lipid peroxidation. As regards temperature, significant differences (p <0.05) were obtained for the content of pigments, both chlorophyll a and carotene, showing a significant interaction (p < 0.05) between the increase in temperature and presence of triclosan.

In the present study, the nutritional value of Tetraselmis suecica and Tisochrysis lutea (previously known as Isochrysis aff galbana T-ISO strain) freeze-dried biomass for feeding Sparus aurata fry was evaluated. A total of 25,500 fry (3.7 mg body weight) were fed for 55 days on diets containing 5 and 10%(w/w) Tetraselmis or Tisochrysis, as well as on a microalgae-free diet. Fish fed 5 % Tetraselmis showed higher growth performance, nutrient utilization, and survival values than fish fed Tisochrysis. The use of microalgae significantly decreased the body lipid content in fry fed the highest microalgae level. Fry fed Tisochrysis-supplemented diets increased the DHA content in muscle, and consequently the EPA/DHA ratio decreased significantly, whatever dietary level considered. In general, digestive protease activities were not adversely affected by dietary microalgae inclusion, although slight variations were observed during fish development. Microalgae utilization causes a positive effect on intestinal mucosa ultrastructure owing to an increase of total enterocyte absorption surface that was observed in fish fed microalgae-supplemented diets. Cluster analysis of data separated clearly fish fed Tisochrysis-supplemented diets from the rest of experimental groups. This study confirms that Tetraselmis freeze-dried biomass can be used as dietary ingredient in started feeds for S. aurata fry, although an inclusion level of 5 % is recommended.

[Resumen] En el medioambiente se produce la entrada de metales pesados no esenciales como el plomo. Lo que podría tener un impacto negativo en la comunidad microalgal, de quien depende la mayor parte de la producción primaria de los ecosistemas acuáticos. En el presente trabajo se estudió el efecto tóxico del plomo sobre la microalga marina Tetraselmis suecica, donde los cultivos se expusieron a concentraciones de 1 ; 5 ; 10 ; 15 y 30 mg L-1 de Plomo durante 96 h y se analizaron los parámetros de crecimiento, contenido celular de pigmentos (clorofila a, clorofila b y carotenos) y producción de fitoquelatinas. Los resultados obtenidos mostraron que el plomo presenta efectos nocivos significativos (p<0,05) en todos los parámetros de crecimiento y producción de pigmentos, y un efecto estimulatorio en la producción de fitoquelatinas, como mecanismo de defensa., [Resumo] No medioámbiente producese a entrada de metais pesados como o chumbo, onde bioacumulaciónse. Isto podería ter un impacto negativo sobre a comunidade de microalgal, da cal depende a maior parte da produción primaria dos ecosistemas acuáticos. No presente traballo, estudase o efecto tóxico do chumbo na microalga mariña Tetraselmis suecica, que a concentracións de 1 ; 5; 10; 15 e 30 mg L-1 de chumbo durante 96 h e foron analizados os parámetros de crecemento, o contido da celular de pigmentos (clorofila a, clorofila b e carotenos) e produción de fitoquelatinas. Os resultados mostraron que o chumbo presentan efectos adversos significativos (p <0,05) nos parámetros de crecemento e produción de pigmento, e presentan un efecto estimulador sobre a produción de fitoquelatinas, como un mecanismo de defensa., [Abstract] In the environment the entrance of heavy metals such as lead, where bioaccumulate occurs. This could have a negative impact on the microalgal community, which oversees most of the primary production of aquatic ecosystems. In this study, we study the toxic effect of lead on marine microalgae Tetraselmis suecica. The crops of Tetraselmis suecica were exposed to concentrations of 1 ; 5 ; 10; 15 and 30 mg L-1 for 96 h Lead. Were analyzed growth parameters, the content of cellular pigment (chlorophyll a, chlorophyll b and carotenes) and phytochelatins production. The results showed that the lead does present significant adverse effects (p <0.05) in all parameters of growth and content of cellular pigment, and stimulatory effect on the production of phytochelatins, as a defense mechanism.

[Resumen]El uso de fertilizantes agrícolas es una preocupación creciente debido a su efecto potencial en microalgas, productores primarios de los ecosistemas acuáticos, esenciales para el mantenimiento del equilibrio de oxígeno, así como para el reciclaje de nutrientes. En este trabajo se emplearon diferentes concentraciones de los fertilizantes agrícolas comerciales Abono Soluble en Agua ONE y Abono Azul Universal NovaTec para el cultivo de la microalga marina Tetraselmis suecica y la microalga dulceacuícola Chlorella vulgaris y se compararon con un medio sin nutrientes y medios de cultivo convencionales. Las concentraciones de fertilizante testadas proporcionaron unas tasas de crecimiento y contenido en proteínas y pigmentos fotosintéticos significativamente mayores que el medio sin nutrientes, próximas a las obtenidas con el medio de cultivo de referencia y a veces, superiores, variando en función del fertilizante y microalga empleados. Los resultados obtenidos han determinado que con el uso de los fertilizantes es posible mejorar el rendimiento de la producción de las microalgas pero para ello es necesario conocer los requerimientos nutritivos de las especies estudiadas, ya que los parámetros óptimos para el crecimiento de las microalgas, así como los rangos tolerados dependen de cada especie., [Abstract] The use of agricultural fertilizers is a growing concern due to their potential effect on microalgae, because they are primary producers of aquatic ecosystems and essential for the maintenance of oxygen balance and the recycling of nutrients. In this work different concentrations of commercial agricultural fertilizer Abono Soluble en Agua ONE and Abono Azul Universal NovaTec were used for the cultivation of the marine microalgae Tetraselmis suecica and the freshwater microalgae Chlorella vulgaris and they were compared with a medium without nutrients and with conventional culture media. Growth rates and protein and photosynthetic pigments content were higher in the cultures with the fertilizer concentrations tested than in the medium without nutrients, and close or even higher than those obtained with the conventional culture media, varying according to the fertilizer and microalgae used. According to the results obtained, the use of fertilizers can improve the yield in the production of microalgae but a better knowledge of the nutritional requirements of each species needed since the optimal growth parameters and tolerance ranges depend on the species.

[EN] Bread is a food with high consumption in the Spanish population. Demand of different varieties of it is increasing, moreover it has to provide extra health nutritional benefits. For this reason this paper aims to the formulation, preparation and subsequent rating of 4 breads made from 4 sourdough which were incorporated 1.5% of 4 different species of microalgae to each of them: Isochrysis galbana, Tetraselmis suecica, Scenedesmus almeriensis and Nannochloropsis gaditana. Microalgae have very large amounts of beneficial compounds to health that they cannot find in other foods of plant origin. Many species have been adopted in the legislation of Novel Foods, which was revalued and offer as an alternative to its use as biofuel or feed. Results of color, viscosity and microbiological analysis for the sourdough, and color, texture and sensory for bread show that the sourdough has a different coloration than normal bread and higher viscosities. In addition, lactic acid bacteria responsible for fermentation have more growth than normal bread. The breads baked from these sourdoughs have similar values in the basic properties of regular bread quality, except for the color, which differs significantly. When the bread was evaluated sensory, they show a possible acceptation in the market, and all of them were highly valued, [ES] El objetivo de presente trabajo es evaluar el efecto de la incorporación de una masa de levadura madre con microalgas al pan. El proyecto pretende desarrollarse en el marco de iniciativas del sector público-privado, teniendo como objetivo estudiar los efectos sobre la masa panaria de la incorporción de microalgas. Evaluar la variación que se produce en las propiedades fisicoquímicas y organolépticas del pan siguiendo un proceso de elaboración artesanal. Para ello se cuanta con el asesoramiento del maestro panadero Jesús Machí que aportará su experiencia en los procesos productivos.

[EN] Bread is a food with high consumption in the Spanish population. Demand of different varieties of it is increasing, moreover it has to provide extra health nutritional benefits. For this reason this paper aims to the formulation, preparation and subsequent rating of 4 breads made from 4 sourdough which were incorporated 1.5% of 4 different species of microalgae to each of them: Isochrysis galbana, Tetraselmis suecica, Scenedesmus almeriensis and Nannochloropsis gaditana. Microalgae have very large amounts of beneficial compounds to health that they cannot find in other foods of plant origin. Many species have been adopted in the legislation of Novel Foods, which was revalued and offer as an alternative to its use as biofuel or feed. Results of color, viscosity and microbiological analysis for the sourdough, and color, texture and sensory for bread show that the sourdough has a different coloration than normal bread and higher viscosities. In addition, lactic acid bacteria responsible for fermentation have more growth than normal bread. The breads baked from these sourdoughs have similar values in the basic properties of regular bread quality, except for the color, which differs significantly. When the bread was evaluated sensory, they show a possible acceptation in the market, and all of them were highly valued, [ES] El objetivo de presente trabajo es evaluar el efecto de la incorporación de una masa de levadura madre con microalgas al pan. El proyecto pretende desarrollarse en el marco de iniciativas del sector público-privado, teniendo como objetivo estudiar los efectos sobre la masa panaria de la incorporción de microalgas. Evaluar la variación que se produce en las propiedades fisicoquímicas y organolépticas del pan siguiendo un proceso de elaboración artesanal. Para ello se cuanta con el asesoramiento del maestro panadero Jesús Machí que aportará su experiencia en los procesos productivos.

[EN] Bread is a food with high consumption in the Spanish population. Demand of different varieties of it is increasing, moreover it has to provide extra health nutritional benefits. For this reason this paper aims to the formulation, preparation and subsequent rating of 4 breads made from 4 sourdough which were incorporated 1.5% of 4 different species of microalgae to each of them: Isochrysis galbana, Tetraselmis suecica, Scenedesmus almeriensis and Nannochloropsis gaditana. Microalgae have very large amounts of beneficial compounds to health that they cannot find in other foods of plant origin. Many species have been adopted in the legislation of Novel Foods, which was revalued and offer as an alternative to its use as biofuel or feed. Results of color, viscosity and microbiological analysis for the sourdough, and color, texture and sensory for bread show that the sourdough has a different coloration than normal bread and higher viscosities. In addition, lactic acid bacteria responsible for fermentation have more growth than normal bread. The breads baked from these sourdoughs have similar values in the basic properties of regular bread quality, except for the color, which differs significantly. When the bread was evaluated sensory, they show a possible acceptation in the market, and all of them were highly valued, [ES] El objetivo de presente trabajo es evaluar el efecto de la incorporación de una masa de levadura madre con microalgas al pan. El proyecto pretende desarrollarse en el marco de iniciativas del sector público-privado, teniendo como objetivo estudiar los efectos sobre la masa panaria de la incorporción de microalgas. Evaluar la variación que se produce en las propiedades fisicoquímicas y organolépticas del pan siguiendo un proceso de elaboración artesanal. Para ello se cuanta con el asesoramiento del maestro panadero Jesús Machí que aportará su experiencia en los procesos productivos.

[EN] Bread is a food with high consumption in the Spanish population. Demand of different varieties of it is increasing, moreover it has to provide extra health nutritional benefits. For this reason this paper aims to the formulation, preparation and subsequent rating of 4 breads made from 4 sourdough which were incorporated 1.5% of 4 different species of microalgae to each of them: Isochrysis galbana, Tetraselmis suecica, Scenedesmus almeriensis and Nannochloropsis gaditana. Microalgae have very large amounts of beneficial compounds to health that they cannot find in other foods of plant origin. Many species have been adopted in the legislation of Novel Foods, which was revalued and offer as an alternative to its use as biofuel or feed. Results of color, viscosity and microbiological analysis for the sourdough, and color, texture and sensory for bread show that the sourdough has a different coloration than normal bread and higher viscosities. In addition, lactic acid bacteria responsible for fermentation have more growth than normal bread. The breads baked from these sourdoughs have similar values in the basic properties of regular bread quality, except for the color, which differs significantly. When the bread was evaluated sensory, they show a possible acceptation in the market, and all of them were highly valued, [ES] El objetivo de presente trabajo es evaluar el efecto de la incorporación de una masa de levadura madre con microalgas al pan. El proyecto pretende desarrollarse en el marco de iniciativas del sector público-privado, teniendo como objetivo estudiar los efectos sobre la masa panaria de la incorporción de microalgas. Evaluar la variación que se produce en las propiedades fisicoquímicas y organolépticas del pan siguiendo un proceso de elaboración artesanal. Para ello se cuanta con el asesoramiento del maestro panadero Jesús Machí que aportará su experiencia en los procesos productivos.

[Resumen] El uso generalizado de filtros solares en productos de cuidado personal, incluyendo los protectores solares y los cosméticos, o como aditivos industriales, ha planteado preocupaciones sobre el posible efecto que pueden presentar sobre los organismos vivos. Esto hace que sea importante la realización de estudios para determinar la ecotoxicidad de estos compuestos. En este trabajo se evalúa el efecto del Octocrileno (OC) y de la combinación de este con la Benzofenona-3 (BP-3), otro filtro solar muy utilizado, sobre la microalga marina Tetraselmis suecica. Se realizaron análisis del crecimiento celular, de la cantidad de pigmentos celulares y de la actividad celular en un ensayo que duró 144h en total. El OC no presenta alteraciones en el crecimiento celular ni en la concentración de pigmentos de la microalga en concentraciones entre 2,5 y 5 mg·L-1, mientras que la BP-3 sí que inhibe el crecimiento celular y reduce la cantidad de carotenoides. La combinación de los dos filtros solares no provoca cambios en el crecimiento celular pero sí aumenta la concentración celular de carotenoides. La actividad, medida mediante la hidrólisis de FDA, es el método que muestra resultados más relevantes. La BP-3, como era de esperar, redujo la actividad en gran medida (3,72 ± 0,31pg de fluoresceína·célula-1·h-1) con respecto al control (17,96 ± 0,75pg de fluoresceína·célula-1·h-1). El OC también presenta un efecto reductor de la actividad celular (9,04 ± 1,05pg de fluoresceína·célula-1·h-1). Este valor es muy próximo al obtenido por la mezcla de OC y BP-3 (8,95 ± 0,20pg de fluoresceína·célula-1·h-1), lo que indica que no existe un efecto sinérgico ni antagonista de los dos filtros solares sobre la actividad de T. suecica., [Abstract] The widespread use of UV filters in personal care products, including sunscreens and cosmetics, or as industrial additives, has raised concerns about the possible impact that they may have on living organisms. This makes important the need for more studies to determine the ecotoxicity of these compounds. In this work the effect of Octocrylene (OC) and the combination of this with the Benzophenone-3 (BP-3), another widely used sunscreen, is evaluated on marine microalgae Tetraselmis suecica. Analysis of cell growth, the amount of cell pigments and cellular activity were performed in a test that lasted 144 hours in total. The OC doesn't cause alterations in cell growth nor microalgal pigment amount in concentrations between 2.5 to 5 mg·L-1, whereas BP-3 inhibits cell growth and reduces the amount of carotenoids. The combination of the two UV filters don't cause changes in cell growth but it increase the cellular concentration of carotenoids. The activity measured by the hydrolysis of FDA, is the method that shows more relevant results. As expected the BP-3 largely reduced cell activity (3.72 ± 0.31pg fluorescein · cell -1· h-1) compared to the control (17.96 ± 0.75pg fluorescein · cell -1· h-1). The OC also has a reducing effect on cell activity (9.04 ± 1.05pg fluorescein · cell -1· h-1). This value is very close to that obtained by the mixture of BP-3 and OC (8.95 ± 0.20pg fluorescein · cell -1· h-1), indicating that there isn't a synergistic or antagonist effect the two UV filters on the activity of T. suecica.

[Resumen] Los microcontaminantes emergentes como el bisfenol A son objeto de estudio en la actualidad por el escaso conocimiento que se posee de éstos al pasar de inadvertida su presencia en el medio ambiente y las consecuencias de la misma. El bisfenol A, empleado industrialmente en numerosos sectores está presente en los ecosistemas acuáticos, vulnerables a la exposición de diferentes productos químicos que afectan de forma directa o indirecta a la biota residente en el medio, como las microalgas que constituyen parte del fitoplancton, base la cadena alimenticia y responsables de más del 50% de la productividad fotosintética primaria en la Tierra. En este trabajo se estudió el posible efecto tóxico del microcontaminante emergente bisfenol A sobre la microalga marina Tetraselmis suecica, una especie importante en el sector de la acuicultura. Los cultivos de T. suecica se expusieron a concentraciones de 0,01 ; 0,5 y 1 mg l-1 de BPA durante 72 h y se analizaron los parámetros de crecimiento, contenido celular de pigmentos (clorofila a y clorofila b) y actividad celular frente a un control en ausencia de BPA. Todos los parámetros analizados han mostrado diferencias significativas entre al menos dos de los cultivos expuestos a diferentes concentraciones de bisfenol A, con lo que podemos determinar que el contaminante ejerce un efecto tóxico sobre el metabolismo de T. suecica y que ésta podría emplearse como indicadora de estrés ambiental por su alta sensibilidad a los parámetros analizados., [Resumo] Os microcontaminantes emerxentes como o bisfenol A son obxeto de estudio na actualidade polo escaso coñecemento que se posee deles ao pasar de inadvertida a sua presenza no medio ambiente e as consecuencias da mesma. O bisfenol A, empleado industrialmente en numerosos sectores está presente nos ecosistemas acuáticos, vulnerables á exposición de diferentes productos químicos que afectan de forma directa ou indirecta á biota residente no medio, como as microalgas que constitúen parte do fitoplancton, base da cadena alimenticia e responsables de más do 50% da productividade fotosintética primaria na terra. Neste traballo estudouse o posible efecto tóxico do microcontaminante emerxente bisfenol A sobre a microalga mariña Tetraselmis suecica, importante no sector dea acuicultura. Os cultivos de T. suecica expuxéronse a concentracións de 0,01 ; 0,5 e 1 mg l-1 de BPA durante 72 h e analizáronse os parámetros de crecemento, contido celular de pigmentos (clorofila a e clorofila b) e actividade celular frente a un control en ausencia de BPA. Todos os parámetros analizados mostraron diferenzas significativas entre polo menos dous dos cultivos expostos a diferentes ! ! 3 concentracións de bisfenol A, co que podemos determinar que o bisfenol A exerce un efecto tóxico sobre o metabolismo de T. suecica e que ésta podería empregarse como indicador de estrés ambiental pola sua alta sensibilidade aos parámetros analizados., [Abstract] The emerging micropollutants such as Bisphenol A are nowadays object of study due to the limited knowledge we have about them because of its unnoticed presence and consequences in the environment. Bisphenol A is industrially used in numerous sectors and it is present in the aquatic ecosystems, which are vulnerable to be exposure to diverse chemical products that affect, on a direct or indirect way, the living biota in the environment (as the microalgae that constitute part of the phytoplankton, which is the basis of the food chain and responsible for more tan 50% of the production of primary photosynthesis on Earth). In this work, it has been studied microalga Tetraselmis suecica, an important species in the aquaculture sector. The crops of Tetraselmis suecica were exposed to concentrations of 0,01; 0,5 and 1 mg l-1 of BPA trough 72 hours and the parameters of growth, the content of cellular pigment (clorophyll a and clorophyll b) and cellular activity were analysed facing a control between at least two of the exposed crops to the different concentrations of Bisphenol A, with which we can determine that the contaminant exerts a toxic effect on the metabolism of Tetraselmis suecica and that it could be use as a indicator of environmental stress due to the high sensitbility to the analyzed parameters.

As fossil fuel prices increase and environmental concerns gain prominence, the development of alternative fuels from biomass has become more important. Biodiesel produced from microalgae is becoming an attractive alternative to share the role of petroleum. Currently it appears that the production of microalgal biodiesel is not economically viable in current environment because it costs more than conventional fuels. Therefore, a new concept is introduced in this article as an option to reduce the total production cost of microalgal biodiesel. The integration of biodiesel production system with methane production via anaerobic digestion is proved in improving the economics and sustainability of overall biodiesel stages. Anaerobic digestion of microalgae produces methane and further be converted to generate electricity. The generated electricity can surrogate the consumption of energy that require in microalgal cultivation, dewatering, extraction and transesterification process. From theoretical calculations, the electricity generated from methane is able to power all of the biodiesel production stages and will substantially reduce the cost of biodiesel production (33% reduction). The carbon emissions of biodiesel production systems are also reduced by approximately 75% when utilizing biogas electricity compared to when the electricity is otherwise purchased from the Victorian grid. The overall findings from this study indicate that the approach of digesting microalgal waste to produce biogas will make the production of biodiesel from algae more viable by reducing the overall cost of production per unit of biodiesel and hence enable biodiesel to be more competitive with existing fuels.

The growth of Tetraselmis suecica was evaluated. The experiment was realized using the Response Surface Methodology (RSM) with Central Composite Rotational Design (CCRD) with two factors, pH and sanguaza/seawater concentration in the range of 7 - 9 and 2 - 5 % (v/v), respectively. The culture media were stirred by bubbling air constantly (0.07 L/s) and continuously illuminated with 40 W of fluorescent light in glass containers of 1.5 L capacity at a temperature of 22.5 ± 2.1 °C. Using the Gompertz mathematical model was determined that from an 8.0 of pH and a ratio of 3.5% of sanguaza/seawater, the Tetraselmis suecica achieves maximum growth. An 8.71 of pH and a ratio of 4.56% of sanguaza/seawater allow the Tetraselmis suecica maximum growth (logN/N0) of 0.659, with a 12.3% of prediction error by applying a mathematical model of 2nd order. According to the study, the values obtained in sanguaza/seawater as a culture medium outperformed the traditionally used culture medium (Guillard F/2 with seawater). The results demonstrate the potential use of the sanguaza/seawater medium in scalable studies on pilot scale production of Tetraselmis suecica, with a view to the production of biodiesel

The growth of Tetraselmis suecica was evaluated. The experiment was realized using the Response Surface Methodology (RSM) with Central Composite Rotational Design (CCRD) with two factors, pH and sanguaza/seawater concentration in the range of 7 - 9 and 2 - 5 % (v/v), respectively. The culture media were stirred by bubbling air constantly (0.07 L/s) and continuously illuminated with 40 W of fluorescent light in glass containers of 1.5 L capacity at a temperature of 22.5 ± 2.1 °C. Using the Gompertz mathematical model was determined that from an 8.0 of pH and a ratio of 3.5% of sanguaza/seawater, the Tetraselmis suecica achieves maximum growth. An 8.71 of pH and a ratio of 4.56% of sanguaza/seawater allow the Tetraselmis suecica maximum growth (logN/N0) of 0.659, with a 12.3% of prediction error by applying a mathematical model of 2nd order. According to the study, the values obtained in sanguaza/seawater as a culture medium outperformed the traditionally used culture medium (Guillard F/2 with seawater). The results demonstrate the potential use of the sanguaza/seawater medium in scalable studies on pilot scale production of Tetraselmis suecica, with a view to the production of biodiesel

[Abstract]The present work reports the use of living cells of the marine microalga Tetraselmis suecica for the biosorption of cadmium ions. For a better understanding of the biosorption characteristics, three fractions of removed cadmium (total, bioadsorbed and intracellular) were measured in the cells after 24 and 72 h of exposure to different initial cadmium concentrations (0.6–45 mg L−1). Both the Langmuir and Freundlich models were suitable for describing the sorption of cadmium ions by this microalga. The maximum sorption capacity was estimated to be 40.22 mg Cd g−1 after 72 h using the Langmuir sorption model. In the lower cadmium concentrations, metal removed intracellularly was higher than that removed on the microalgal cell surface. Therefore, the intracellular fraction contributed more to the total removed cadmium than the fraction bioadsorbed to the cellular surface. The results showed that the cadmium removal capacity using living biomass could be much more effective than with non-living biomass due to the intracellular bioaccumulation. According to the microorganism selected and its tolerance to the toxic effect of the metal, the cadmium content in the intracellular fraction can become very significant, just like it happened with Tetraselmis.

Background: Conventional biodiesel production relies on trans-esterification of lipids extracted from vegetable crops. However, the use of valuable vegetable food stocks as raw material for biodiesel production makes it an unfeasibly expensive process. Used cooking oil is a finite resource and requires extra downstream processing, which affects the amount of biodiesel that can be produced and the economics of the process. Lipids extracted from microalgae are considered an alternative raw material for biodiesel production. This is primarily due to the fast growth rate of these species in a simple aquaculture environment. However, the dilute nature of microalgae culture puts a huge economic burden on the dewatering process especially on an industrial scale. This current study explores the performance and economic viability of chemical flocculation and tangential flow filtration (TFF) for the dewatering of Tetraselmis suecicamicroalgae culture. Results: Results show that TFF concentrates the microalgae feedstock up to 148 times by consuming 2.06 kWh m-3 of energy while flocculation consumes 14.81 kWhm-3 to concentrate the microalgae up to 357 times. Economic evaluation demonstrates that even though TFF has higher initial capital investment than polymer flocculation, the payback period for TFF at the upper extreme ofmicroalgae revenue is ∼1.5 years while that of flocculation is ∼3 years. Conclusion: These results illustrate that improved dewatering levels can be achieved more economically by employing TFF. The performances of these two techniques are also compared with other dewatering techniques.

The quality and the productivity of microalgal cultures depend on different physicochemical factors like salinity, pH, nutrient and trace element (including trace metals) concentration in the culture medium. During this doctoral study, the bioavailability of four metals for microalgae was tested in coastal seawater and several salt groundwaters. The bioavailability of a metal depends on its own total concentration as well as that of ligands in the medium, and on the relative affinity of each ligand towards the given metal. After a comparative study of the quality of algae grown in coastal seawater and salt groundwaters, the complexation capacities of these media were studied to allow a better understanding of the observed variations of metal bioaccumualtion in the produced microalgae. An experimental study with a new artificial medium (DAM) developed during our work allowed to put forward some hypotheses regarding the interspecific variations of metal bioaccumulation., La qualité et la production d'une culture de microalgues sont dépendantes de différents facteurs physico-chimiques : salinité, pH, concentration en nutriments majeurs et en oligoéléments dont les métaux traces dans le milieu de culture. Dans ce travail de doctorat, la biodisponibilité de quatre métaux pour des microalgues est étudiée dans les eaux marine côtière et souterraine salée. La biodisponibilité d'un métal est dépendante de sa concentration totale et de celle des ligands présents dans le milieu ainsi que de l'affinité respective de ces ligands pour le métal. Suite à l'étude comparative de la qualité des algues produites, les capacités de complexation des eaux souterraines salées et l'eau de mer côtière ont été étudiées afin de mieux comprendre les variations de bioaccumulation des métaux par les microalgues. Une approche expérimentale sur le milieu artificiel DAM élaboré dans ce travail a permis de formuler des hypothèses sur les variations interspécifiques de la bioaccumulation des métaux.

The quality and the productivity of microalgal cultures depend on different physicochemical factors like salinity, pH, nutrient and trace element (including trace metals) concentration in the culture medium. During this doctoral study, the bioavailability of four metals for microalgae was tested in coastal seawater and several salt groundwaters. The bioavailability of a metal depends on its own total concentration as well as that of ligands in the medium, and on the relative affinity of each ligand towards the given metal. After a comparative study of the quality of algae grown in coastal seawater and salt groundwaters, the complexation capacities of these media were studied to allow a better understanding of the observed variations of metal bioaccumualtion in the produced microalgae. An experimental study with a new artificial medium (DAM) developed during our work allowed to put forward some hypotheses regarding the interspecific variations of metal bioaccumulation., La qualité et la production d'une culture de microalgues sont dépendantes de différents facteurs physico-chimiques : salinité, pH, concentration en nutriments majeurs et en oligoéléments dont les métaux traces dans le milieu de culture. Dans ce travail de doctorat, la biodisponibilité de quatre métaux pour des microalgues est étudiée dans les eaux marine côtière et souterraine salée. La biodisponibilité d'un métal est dépendante de sa concentration totale et de celle des ligands présents dans le milieu ainsi que de l'affinité respective de ces ligands pour le métal. Suite à l'étude comparative de la qualité des algues produites, les capacités de complexation des eaux souterraines salées et l'eau de mer côtière ont été étudiées afin de mieux comprendre les variations de bioaccumulation des métaux par les microalgues. Une approche expérimentale sur le milieu artificiel DAM élaboré dans ce travail a permis de formuler des hypothèses sur les variations interspécifiques de la bioaccumulation des métaux.

The quality and the productivity of microalgal cultures depend on different physicochemical factors like salinity, pH, nutrient and trace element (including trace metals) concentration in the culture medium. During this doctoral study, the bioavailability of four metals for microalgae was tested in coastal seawater and several salt groundwaters. The bioavailability of a metal depends on its own total concentration as well as that of ligands in the medium, and on the relative affinity of each ligand towards the given metal. After a comparative study of the quality of algae grown in coastal seawater and salt groundwaters, the complexation capacities of these media were studied to allow a better understanding of the observed variations of metal bioaccumualtion in the produced microalgae. An experimental study with a new artificial medium (DAM) developed during our work allowed to put forward some hypotheses regarding the interspecific variations of metal bioaccumulation., La qualité et la production d'une culture de microalgues sont dépendantes de différents facteurs physico-chimiques : salinité, pH, concentration en nutriments majeurs et en oligoéléments dont les métaux traces dans le milieu de culture. Dans ce travail de doctorat, la biodisponibilité de quatre métaux pour des microalgues est étudiée dans les eaux marine côtière et souterraine salée. La biodisponibilité d'un métal est dépendante de sa concentration totale et de celle des ligands présents dans le milieu ainsi que de l'affinité respective de ces ligands pour le métal. Suite à l'étude comparative de la qualité des algues produites, les capacités de complexation des eaux souterraines salées et l'eau de mer côtière ont été étudiées afin de mieux comprendre les variations de bioaccumulation des métaux par les microalgues. Une approche expérimentale sur le milieu artificiel DAM élaboré dans ce travail a permis de formuler des hypothèses sur les variations interspécifiques de la bioaccumulation des métaux.

The quality and the productivity of microalgal cultures depend on different physicochemical factors like salinity, pH, nutrient and trace element (including trace metals) concentration in the culture medium. During this doctoral study, the bioavailability of four metals for microalgae was tested in coastal seawater and several salt groundwaters. The bioavailability of a metal depends on its own total concentration as well as that of ligands in the medium, and on the relative affinity of each ligand towards the given metal. After a comparative study of the quality of algae grown in coastal seawater and salt groundwaters, the complexation capacities of these media were studied to allow a better understanding of the observed variations of metal bioaccumualtion in the produced microalgae. An experimental study with a new artificial medium (DAM) developed during our work allowed to put forward some hypotheses regarding the interspecific variations of metal bioaccumulation., La qualité et la production d'une culture de microalgues sont dépendantes de différents facteurs physico-chimiques : salinité, pH, concentration en nutriments majeurs et en oligoéléments dont les métaux traces dans le milieu de culture. Dans ce travail de doctorat, la biodisponibilité de quatre métaux pour des microalgues est étudiée dans les eaux marine côtière et souterraine salée. La biodisponibilité d'un métal est dépendante de sa concentration totale et de celle des ligands présents dans le milieu ainsi que de l'affinité respective de ces ligands pour le métal. Suite à l'étude comparative de la qualité des algues produites, les capacités de complexation des eaux souterraines salées et l'eau de mer côtière ont été étudiées afin de mieux comprendre les variations de bioaccumulation des métaux par les microalgues. Une approche expérimentale sur le milieu artificiel DAM élaboré dans ce travail a permis de formuler des hypothèses sur les variations interspécifiques de la bioaccumulation des métaux.

The quality and the productivity of microalgal cultures depend on different physicochemical factors like salinity, pH, nutrient and trace element (including trace metals) concentration in the culture medium. During this doctoral study, the bioavailability of four metals for microalgae was tested in coastal seawater and several salt groundwaters. The bioavailability of a metal depends on its own total concentration as well as that of ligands in the medium, and on the relative affinity of each ligand towards the given metal. After a comparative study of the quality of algae grown in coastal seawater and salt groundwaters, the complexation capacities of these media were studied to allow a better understanding of the observed variations of metal bioaccumualtion in the produced microalgae. An experimental study with a new artificial medium (DAM) developed during our work allowed to put forward some hypotheses regarding the interspecific variations of metal bioaccumulation., La qualité et la production d'une culture de microalgues sont dépendantes de différents facteurs physico-chimiques : salinité, pH, concentration en nutriments majeurs et en oligoéléments dont les métaux traces dans le milieu de culture. Dans ce travail de doctorat, la biodisponibilité de quatre métaux pour des microalgues est étudiée dans les eaux marine côtière et souterraine salée. La biodisponibilité d'un métal est dépendante de sa concentration totale et de celle des ligands présents dans le milieu ainsi que de l'affinité respective de ces ligands pour le métal. Suite à l'étude comparative de la qualité des algues produites, les capacités de complexation des eaux souterraines salées et l'eau de mer côtière ont été étudiées afin de mieux comprendre les variations de bioaccumulation des métaux par les microalgues. Une approche expérimentale sur le milieu artificiel DAM élaboré dans ce travail a permis de formuler des hypothèses sur les variations interspécifiques de la bioaccumulation des métaux.

In an attempt to provide cost-effective alternatives to live microalgae and to simplify hatchery-nursery procedures, concentrated microalgae appear to be very promising. Due to its high preservation ability, Prasinophytes appear to be good candidates for such alternative diets. Nevertheless, in a previous study the utilization of Tetraselmis suecica was only conceivable for old Crassostrea gigas larvae. In the present work its nutritional quality has been accordingly searched on ]apanese oyster's juveniles. Whatever the assemblages and condition, fresh or preserved microalgae, T. suecica did not allow an adequate postlarval development in C. gigas., L'utilisation de microalgues concentrées et conservées est une des voies envisagées pour améliorer les procédures en écloserie-nurserie de mollusques et en diminuer les coûts de production. Comme elles présentent de bonnes aptitudes à la conservation, les Prasinophycées s'avèrent de bons candidats potentiels. Au cours d'une précédente étude il a été démontré que l'utilisation de Tetraselmis suecica n'était envisageable que chez des larves âgées de Crassostrea gigas. Dans le présent travail, la valeur alimentaire de cette algue fraîche et conservée a donc été recherchée sur des juvéniles de l'huître japonaise. Quel que soit l'assemblage considéré et quelle que soit sa forme, fraîche ou conservée, T. suecica ne permet pas un développement postlarvaire satisfaisant chez C. gigas.

In an attempt to provide cost-effective alternatives to live microalgae and to simplify hatchery-nursery procedures, concentrated microalgae appear to be very promising. Due to its high preservation ability, Prasinophytes appear to be good candidates for such alternative diets. Nevertheless, in a previous study the utilization of Tetraselmis suecica was only conceivable for old Crassostrea gigas larvae. In the present work its nutritional quality has been accordingly searched on ]apanese oyster's juveniles. Whatever the assemblages and condition, fresh or preserved microalgae, T. suecica did not allow an adequate postlarval development in C. gigas., L'utilisation de microalgues concentrées et conservées est une des voies envisagées pour améliorer les procédures en écloserie-nurserie de mollusques et en diminuer les coûts de production. Comme elles présentent de bonnes aptitudes à la conservation, les Prasinophycées s'avèrent de bons candidats potentiels. Au cours d'une précédente étude il a été démontré que l'utilisation de Tetraselmis suecica n'était envisageable que chez des larves âgées de Crassostrea gigas. Dans le présent travail, la valeur alimentaire de cette algue fraîche et conservée a donc été recherchée sur des juvéniles de l'huître japonaise. Quel que soit l'assemblage considéré et quelle que soit sa forme, fraîche ou conservée, T. suecica ne permet pas un développement postlarvaire satisfaisant chez C. gigas.

In an attempt to provide cost-effective alternatives to live microalgae and to simplify hatchery-nursery procedures, concentrated microalgae appear to be very promising. Due to its high preservation ability, Prasinophytes appear to be good candidates for such alternative diets. Nevertheless, in a previous study the utilization of Tetraselmis suecica was only conceivable for old Crassostrea gigas larvae. In the present work its nutritional quality has been accordingly searched on ]apanese oyster's juveniles. Whatever the assemblages and condition, fresh or preserved microalgae, T. suecica did not allow an adequate postlarval development in C. gigas., L'utilisation de microalgues concentrées et conservées est une des voies envisagées pour améliorer les procédures en écloserie-nurserie de mollusques et en diminuer les coûts de production. Comme elles présentent de bonnes aptitudes à la conservation, les Prasinophycées s'avèrent de bons candidats potentiels. Au cours d'une précédente étude il a été démontré que l'utilisation de Tetraselmis suecica n'était envisageable que chez des larves âgées de Crassostrea gigas. Dans le présent travail, la valeur alimentaire de cette algue fraîche et conservée a donc été recherchée sur des juvéniles de l'huître japonaise. Quel que soit l'assemblage considéré et quelle que soit sa forme, fraîche ou conservée, T. suecica ne permet pas un développement postlarvaire satisfaisant chez C. gigas.

In an attempt to provide cost-effective alternatives to live microalgae and to simplify hatchery-nursery procedures, concentrated microalgae appear to be very promising. Due to its high preservation ability, Prasinophytes appear to be good candidates for such alternative diets. Nevertheless, in a previous study the utilization of Tetraselmis suecica was only conceivable for old Crassostrea gigas larvae. In the present work its nutritional quality has been accordingly searched on ]apanese oyster's juveniles. Whatever the assemblages and condition, fresh or preserved microalgae, T. suecica did not allow an adequate postlarval development in C. gigas., L'utilisation de microalgues concentrées et conservées est une des voies envisagées pour améliorer les procédures en écloserie-nurserie de mollusques et en diminuer les coûts de production. Comme elles présentent de bonnes aptitudes à la conservation, les Prasinophycées s'avèrent de bons candidats potentiels. Au cours d'une précédente étude il a été démontré que l'utilisation de Tetraselmis suecica n'était envisageable que chez des larves âgées de Crassostrea gigas. Dans le présent travail, la valeur alimentaire de cette algue fraîche et conservée a donc été recherchée sur des juvéniles de l'huître japonaise. Quel que soit l'assemblage considéré et quelle que soit sa forme, fraîche ou conservée, T. suecica ne permet pas un développement postlarvaire satisfaisant chez C. gigas.

In an attempt to provide cost-effective alternatives to live microalgae and to simplify hatchery-nursery procedures, concentrated microalgae appear to be very promising. Due to its high preservation ability, Prasinophytes appear to be good candidates for such alternative diets. Nevertheless, in a previous study the utilization of Tetraselmis suecica was only conceivable for old Crassostrea gigas larvae. In the present work its nutritional quality has been accordingly searched on ]apanese oyster's juveniles. Whatever the assemblages and condition, fresh or preserved microalgae, T. suecica did not allow an adequate postlarval development in C. gigas., L'utilisation de microalgues concentrées et conservées est une des voies envisagées pour améliorer les procédures en écloserie-nurserie de mollusques et en diminuer les coûts de production. Comme elles présentent de bonnes aptitudes à la conservation, les Prasinophycées s'avèrent de bons candidats potentiels. Au cours d'une précédente étude il a été démontré que l'utilisation de Tetraselmis suecica n'était envisageable que chez des larves âgées de Crassostrea gigas. Dans le présent travail, la valeur alimentaire de cette algue fraîche et conservée a donc été recherchée sur des juvéniles de l'huître japonaise. Quel que soit l'assemblage considéré et quelle que soit sa forme, fraîche ou conservée, T. suecica ne permet pas un développement postlarvaire satisfaisant chez C. gigas.

[Abstract] Cadmium removal by living cells of the marine microalga Tetraselmis suecica was tested in cultures exposed to different cadmium concentrations (0.6, 3, 6, 15, 30 and 45 mg/l). The EC50 for growth was 7.9 mg Cd/l after six days of exposure. The cadmium removed was proportional to the concentration of this metal in the medium and it was dependent on the time of exposure; cultures with higher cadmium concentration removed a higher amount of this metal. In cultures exposed to 0.6 mg/l, T. suecica cells removed 98.1% of added cadmium with 0.392x10-6ug Cd/cell, whereas in cultures with 45 mg/l only 7.7% was removed with 16.052x10-6ug Cd/cell. The highest amount of cadmium removed per liter of culture was observed in cultures exposed to 6 mg/l, with 3.577 mg/l of cadmium. After six days of incubation, the higher proportion of cadmium was bioaccumulated intracellularly in all cultures except in 45 mg/l cultures, the percentage of intracellular cadmium being always more than 50%. The highest percentage of bioadsorbed cadmium (60.1%) was found in cells of cultures with the highest cadmium concentration (45 mg/l). Furthermore, a relation between intracellular cadmium and the concentration of sulfhydryl groups was observed.

The nutritive value of the marine microalgaeTetraselmis suecica, Isochrysis galbana, Dunaliella tertiolecta and Chlorella stigmatophora was studied in diets given to rats. Biological assays were carried out in order to determine the Protein Efficiency Ratio (PER) and the Food Conversion Efficiency (FCE). Each dried microalga was fed to weaning Wistar albino rats as the sole protein source at a protein level of 12%. Control rats were given diets containing 12 % casein. Food consumption was similar in all groups. PER values obtained were 1.14 with T. suecica diet, 1.13 with I. galbana diet, 2.07 with D. tertiolecta diet and 1.13 with C. stigmatophora diet (casein, 2.50). FCE values followed a similar pattern. The data showed that the marine microalga D. tertiolecta is a source of protein of good quality. Its PER is quite high, compared to vegetable and cereal proteins, and compares favourably with other microbial protein sources, such as yeasts or different freshwater microalgae. Haematological tests showed no significant differences among the groups in haemoglobin levels, red and white blood cell counts, differential count and mean corpuscular volume. Different blood parameters were also determined and a significant decrease in triglycerides levels appeared with all the microalgal diets, whereas a significant decrease in cholesterol appeared in D. tertiolecta and C. stigmatophora diets.

The effects of three organic compounds were tested on one of the most used marine micro-algae in the aquaculture of molluscs and crustaceans, Tetraselmis suecica. Studies were made in axenic conditions with yeast extract, peptone and glucose added to the culture medium, each alone, in combinations of two or all together. Medium without any organic compound was used for the control. Cultures containing yeast extract grew best, reaching maximum cell density of 3.79 × 106 and 3.84 × 106 cells ml−1. The organic carbon source affected the biochemical composition. The components most affected were the carbohydrates, with values between 6.5 pg cell−1 in control cultures and 48.5 pg cell−1 in glucose cultures. Protein content ranged between 27.5 pg cell−1 in control cultures and 88.6 pg cell−1in yeast + glucose + peptone cultures. The lipid content changed little. Maximum protein yields were reached in cultures with yeast + glucose and with yeast - glucose - peptone, with values of 24.6 and 28.2 mg 1−1 d−1, respectively. These values are 22 and 25 times those in control cultures. A maximum carbohydrate yield of 7.9 mg carbohydrate per litre per day was obtained in yeast + glucose + peptone cultures, 27 times that in the control cultures. The maximum lipid yield was obtained with yeast + glucose + peptone and yeast + glucose. Maximum energy values were 308 kcal 1− in yeast extract - glucose - peptone cultures and 279 kcal 1−1 in yeast extract + glucose cultures. Gross energy values in control cultures were 24.5 kcal 1−1, but peptone cultures presented the minimum energy value, 22 kcal 1−1. The yeast extract: glucose ratio in the culture medium was optimized. A ratio 2:1 produced the best yields in cells, protein, carbohydrate and gross energy.

[Résumé] Croissance et composition biochimique de la microalgue TetrasellIIis sllecica dans des cultures mixotrophiques avec différents sucres et aminoacides. Trois sucres, fructose, saccharose et manose et trois acides aminés (alanyne, lysine et méthyonine) ont été testés comme stimulants potentiels de la croissance chez la microalgue Tetraselmis suecica. Celle-ci est cultivée en absence de bactéries et a une intensité de lumière de 850 lux. La croissance et la composition biochimique chez T. suecica sont affectées par les substrats organiques testés. Le fructose stimule la croissance mais les autres sucres et l'alanyne sont sans effet. La lysine et la méthyonine réduisent la croissance par rapport aux cultures servant de contrôle. La composition biochimique cellulaire dépend de la nature du substrat organique testé mais elle varie à peine en fonction de la concentration. Les cultures enrichies en sucres présentent les protéines cellulaires les plus abondantes, tandis que pour les cultures enrichies en acides aminés, les lipides sont plus abondants., [Abstract] Growth and biochemical composition of the marine microalga TetrasellIIis sllecica in mixotrophic cultures witf7 different sugars and amino acids. Three sugars (fructose, sucrose and mannose) and three amino acids (alanine, lysine, and methionine) have been tested as potential growth factors for the marine microalgae Tetraselmis suecica, in axenic cultures, at 850 lux light intensity. The organic compounds assayed affected the growth and biochemical composition of T. suecica. Growth stimulation was achieved only in cultures added with fru ctose, whereas growth was not affected in the cultures with the remaining sugars and alanine. Growth was inhibited in the cultures added with lysine and methionine. Biochemical cellular composition was affected by the nature of the organic compound added, but not by the concentration used. Proteins were the main cellular constituent in the cultures carried out with sugars, while in those with amino acids the main cellular fraction was lipids.

The use of the commercial nutrient Algal-1 was studied in mass cultures of the marine microalgaeTetraselmis suecica, Dunaliella tertiolecta, Isochrysis galbana and Phaeodactylum tricornutum, in comparison with the use of media such as ES-Provasoli, and Walne medium. Maximum cell concentrations were always found in Algal-1 cultures and these values were always significantly higher than those obtained in the remaining media. The cellular density obtained in Algal-1 cultures was between 59% and 79% higher than that obtained in the traditional culture media used for T. suecica, between 70% and 109% for D. tertiolecta, between 33% and 60% for I. galbana and between 63% and 105% for P. tricornutum. The culture medium used affected the chemical composition of microalgal cells. Protein is the major cellular component for all the sepcies assayed and with all the media proved. Maximum values of protein/cell were obtained in Algal-1 cultures, except for P. tricornutum, whereas maximum values of reserve products (carbohydrates and lipids) never occurred in Algal-1 cultures, except for T. suecica. Differences in the protein content were higher than those found in the other cellular constituents. Maximum values of protein, lipids and carbohydrates per liter of culture always occurred in Algal-1 cultures, with significant differences in the values obtained in the remaining cultures. Maximum protein concentration (mg/liter) obtained in Algal-1 cultures was between 155% and 334% higher than that obtained in the remaining media for T. suecica, between 75% and 194% for D. tertiolecta, between 75% and 195% for I. galbana and between 93% and 225% for P. tricornutum. Daily protein yields (mg liter/day) also occurred in Algal-1 cultures. Ratios between protein values per liter of culture reached in each traditional medium and those reached in Algal-1 show values between 0•2 and 0•6 for protein content; therefore, Algal-1 cultures produced between 2 and 5 times more protein than the remain

The different growth stages of three marine unicellular algae used in aquaculture, Isochrysis galbana, Chaetoceros calcitrans forma pumilum and tetraselmis suecica have been studied for 50 days under controlled culture conditions using a particle meter. At the same time, the size spectrum of the cells has been determined using a C 1000 scanner. The exponential growth stage is 11 days in the first two species, and 13 in the last one. Chaetoceros calcitrans forma pumilum is the smallest with an average size of 3.5 µm. Its cellular volume is constant. The average size of Isochrysis galbana is 4.5 µm. An increase of the cellular volume is observed through its stationary stage. The modal size of Tetraselmis suecica is 8 µm. Again, an increase in the cellular volume is observed during its stationary stage., Les différentes phases de croissance de trois algues unicellulaires marines utilisées en aquaculture, Isochrysis galbana, Chaetoceros calcitrans forma pumilum et tetraselmis suecica ont été étudiées pendant 50 jours au moyen d'un compteur de particules sous des conditions de cultures contrôlées. Parallèlement, le spectre de taille des cellules a été déterminé avec analyseur C 1000. La phase exponentielle de croissance est de 11 jours chez les deux premières espèces, de 13 chez la dernière . Chaetoceros calcitrans forma pumilum est la pus petite avec une taille :moyenne de 3. 5 µm. Son volume cellulaire est constant. La taille moyenne d' Isochrysis galbana est de 4. 5 µm. Une augmentation du volume cellulaire est observée en phase stationnaire. La taille modale de Tetraselmis suecica est de 8µm. Là encore, une augmentation du volume cellulaire apparaît en phase stationnaire

The growth of post-larval P. serratus has been studied until the appearance of secondary sexual characters, in order to eliminate the influence of sex ratio on the mean wt. The influence of temp on intermolt period and number of molts was observed in male and female kept individually. Different sorts of food of natural origin have been tested. The rearing of post-larval lots metamorphosed at different times of the yr showed that the growth of P. serratus is conditioned not only by the temp, but also by the season. The food conversion ratio was defined in relation to the sex and age of the prawns. Shelters allowed the author to obtain a ratio of survival which varied post-larvae per square meter. The sex ratio established from several breedings as soon as the sexual secondary characters, appeared, did not show, on an average, a predominance of male or female. The rearing of 800 post larvae in a tank of 1500 1 heated at 20{degree}C, during 20 months, showed that at the age of 7 months, the prawns hardly reached a commercial wt. The activity of female was essentially the intensive breeding of P. serratus does not seem of commercial interest now. It seems more advisable to carry out extensive breeding in lagoons along the coast during the period of highest growth between April and Nov.

The different growth stages of three marine unicellular algae used in aquaculture, Isochrysis galbana, Chaetoceros calcitrans forma pumilum and tetraselmis suecica have been studied for 50 days under controlled culture conditions using a particle meter. At the same time, the size spectrum of the cells has been determined using a C 1000 scanner. The exponential growth stage is 11 days in the first two species, and 13 in the last one. Chaetoceros calcitrans forma pumilum is the smallest with an average size of 3.5 µm. Its cellular volume is constant. The average size of Isochrysis galbana is 4.5 µm. An increase of the cellular volume is observed through its stationary stage. The modal size of Tetraselmis suecica is 8 µm. Again, an increase in the cellular volume is observed during its stationary stage., Les différentes phases de croissance de trois algues unicellulaires marines utilisées en aquaculture, Isochrysis galbana, Chaetoceros calcitrans forma pumilum et tetraselmis suecica ont été étudiées pendant 50 jours au moyen d'un compteur de particules sous des conditions de cultures contrôlées. Parallèlement, le spectre de taille des cellules a été déterminé avec analyseur C 1000. La phase exponentielle de croissance est de 11 jours chez les deux premières espèces, de 13 chez la dernière . Chaetoceros calcitrans forma pumilum est la pus petite avec une taille :moyenne de 3. 5 µm. Son volume cellulaire est constant. La taille moyenne d' Isochrysis galbana est de 4. 5 µm. Une augmentation du volume cellulaire est observée en phase stationnaire. La taille modale de Tetraselmis suecica est de 8µm. Là encore, une augmentation du volume cellulaire apparaît en phase stationnaire

The growth of post-larval P. serratus has been studied until the appearance of secondary sexual characters, in order to eliminate the influence of sex ratio on the mean wt. The influence of temp on intermolt period and number of molts was observed in male and female kept individually. Different sorts of food of natural origin have been tested. The rearing of post-larval lots metamorphosed at different times of the yr showed that the growth of P. serratus is conditioned not only by the temp, but also by the season. The food conversion ratio was defined in relation to the sex and age of the prawns. Shelters allowed the author to obtain a ratio of survival which varied post-larvae per square meter. The sex ratio established from several breedings as soon as the sexual secondary characters, appeared, did not show, on an average, a predominance of male or female. The rearing of 800 post larvae in a tank of 1500 1 heated at 20{degree}C, during 20 months, showed that at the age of 7 months, the prawns hardly reached a commercial wt. The activity of female was essentially the intensive breeding of P. serratus does not seem of commercial interest now. It seems more advisable to carry out extensive breeding in lagoons along the coast during the period of highest growth between April and Nov.

The different growth stages of three marine unicellular algae used in aquaculture, Isochrysis galbana, Chaetoceros calcitrans forma pumilum and tetraselmis suecica have been studied for 50 days under controlled culture conditions using a particle meter. At the same time, the size spectrum of the cells has been determined using a C 1000 scanner. The exponential growth stage is 11 days in the first two species, and 13 in the last one. Chaetoceros calcitrans forma pumilum is the smallest with an average size of 3.5 µm. Its cellular volume is constant. The average size of Isochrysis galbana is 4.5 µm. An increase of the cellular volume is observed through its stationary stage. The modal size of Tetraselmis suecica is 8 µm. Again, an increase in the cellular volume is observed during its stationary stage., Les différentes phases de croissance de trois algues unicellulaires marines utilisées en aquaculture, Isochrysis galbana, Chaetoceros calcitrans forma pumilum et tetraselmis suecica ont été étudiées pendant 50 jours au moyen d'un compteur de particules sous des conditions de cultures contrôlées. Parallèlement, le spectre de taille des cellules a été déterminé avec analyseur C 1000. La phase exponentielle de croissance est de 11 jours chez les deux premières espèces, de 13 chez la dernière . Chaetoceros calcitrans forma pumilum est la pus petite avec une taille :moyenne de 3. 5 µm. Son volume cellulaire est constant. La taille moyenne d' Isochrysis galbana est de 4. 5 µm. Une augmentation du volume cellulaire est observée en phase stationnaire. La taille modale de Tetraselmis suecica est de 8µm. Là encore, une augmentation du volume cellulaire apparaît en phase stationnaire

The growth of post-larval P. serratus has been studied until the appearance of secondary sexual characters, in order to eliminate the influence of sex ratio on the mean wt. The influence of temp on intermolt period and number of molts was observed in male and female kept individually. Different sorts of food of natural origin have been tested. The rearing of post-larval lots metamorphosed at different times of the yr showed that the growth of P. serratus is conditioned not only by the temp, but also by the season. The food conversion ratio was defined in relation to the sex and age of the prawns. Shelters allowed the author to obtain a ratio of survival which varied post-larvae per square meter. The sex ratio established from several breedings as soon as the sexual secondary characters, appeared, did not show, on an average, a predominance of male or female. The rearing of 800 post larvae in a tank of 1500 1 heated at 20{degree}C, during 20 months, showed that at the age of 7 months, the prawns hardly reached a commercial wt. The activity of female was essentially the intensive breeding of P. serratus does not seem of commercial interest now. It seems more advisable to carry out extensive breeding in lagoons along the coast during the period of highest growth between April and Nov.

The different growth stages of three marine unicellular algae used in aquaculture, Isochrysis galbana, Chaetoceros calcitrans forma pumilum and tetraselmis suecica have been studied for 50 days under controlled culture conditions using a particle meter. At the same time, the size spectrum of the cells has been determined using a C 1000 scanner. The exponential growth stage is 11 days in the first two species, and 13 in the last one. Chaetoceros calcitrans forma pumilum is the smallest with an average size of 3.5 µm. Its cellular volume is constant. The average size of Isochrysis galbana is 4.5 µm. An increase of the cellular volume is observed through its stationary stage. The modal size of Tetraselmis suecica is 8 µm. Again, an increase in the cellular volume is observed during its stationary stage., Les différentes phases de croissance de trois algues unicellulaires marines utilisées en aquaculture, Isochrysis galbana, Chaetoceros calcitrans forma pumilum et tetraselmis suecica ont été étudiées pendant 50 jours au moyen d'un compteur de particules sous des conditions de cultures contrôlées. Parallèlement, le spectre de taille des cellules a été déterminé avec analyseur C 1000. La phase exponentielle de croissance est de 11 jours chez les deux premières espèces, de 13 chez la dernière . Chaetoceros calcitrans forma pumilum est la pus petite avec une taille :moyenne de 3. 5 µm. Son volume cellulaire est constant. La taille moyenne d' Isochrysis galbana est de 4. 5 µm. Une augmentation du volume cellulaire est observée en phase stationnaire. La taille modale de Tetraselmis suecica est de 8µm. Là encore, une augmentation du volume cellulaire apparaît en phase stationnaire

The growth of post-larval P. serratus has been studied until the appearance of secondary sexual characters, in order to eliminate the influence of sex ratio on the mean wt. The influence of temp on intermolt period and number of molts was observed in male and female kept individually. Different sorts of food of natural origin have been tested. The rearing of post-larval lots metamorphosed at different times of the yr showed that the growth of P. serratus is conditioned not only by the temp, but also by the season. The food conversion ratio was defined in relation to the sex and age of the prawns. Shelters allowed the author to obtain a ratio of survival which varied post-larvae per square meter. The sex ratio established from several breedings as soon as the sexual secondary characters, appeared, did not show, on an average, a predominance of male or female. The rearing of 800 post larvae in a tank of 1500 1 heated at 20{degree}C, during 20 months, showed that at the age of 7 months, the prawns hardly reached a commercial wt. The activity of female was essentially the intensive breeding of P. serratus does not seem of commercial interest now. It seems more advisable to carry out extensive breeding in lagoons along the coast during the period of highest growth between April and Nov.

The marine microalga Tetraselmis suecica is known for its ability to tolerate a wide range of salt concentrations. Cultures were grown under 48 different nutrient concentration-salinity conditions, ranging from 2 to 64 mM NaNO3 and from 0 to 35‰ S. Salinity was more important for the growth rate of the microalgae when it was related to the nutrient concentration in the culture medium. Optimal growth conditions were between 25 and 35‰ salinity and nutrient concentrations of 2, 4 and 8 mM of NaNO3, resulting in 0.55 doublings/day and a maximum cellular density of 1.3 × 106 cells/ml. Variations in salinity and in nutrient concentration had a greater effect on the final biomass than on the growth velocity. The total protein of the culture and protein per cell increased when the salinity increased for a given nutrient concentration. The total protein of the cultures decreased when the nutrient concentration increased for a given salinity. Protein per cell decreased with increasing salinity up to 20‰ but from this point of the process was reversed. The nitrate-protein transformation rate increased with the salinity and decreased with increasing nutrient concentrations. The maximum rate was 64%.

The incorporation of powdered marine microalgae in fish diets can substitute, at least in part, for the addition of minerals to the diet. In diets for freshwater fishes, the incorporation of 33% of powdered marine microalgae can supply some of the mineral element requirements. The incorporation of microalgal powder in diets for marine fishes appears more effective, since lower percentages are needed to cover the mineral requirements. Most mineral needs of turbot can be covered with low percentages of marine microalgal powder in the diet: 3.8% of Tetraselmis suecica, 5.7% of Isochrysis galbana, 3.57% of Dunaliella tertiolecta and 3.9% of Chlorella stigmatophora. Mn and Co must, however, be added. Thus, incorporation of small amounts of marine microalgae in diets can replace a mineral mixture.

[Abstract] The marine microalgae Tetraselmis suecica, Isochrysis galbana, Dunaliella tertiolecta and Chlorella stigmatophora are good biological sources of single cell protein (SCP). Protein content accounts for 39.12%–54.20% of the dry matter, D. tertiolecta having the highest. Lysine values are between 3.67 and 4.52 g/100 g of protein, and thus are higher than those for freshwater species. The total nucleic acid content is less than 7% of the dry matter; this value is definitely lower than that for yeasts or bacteria, commonly used as SCP sources. Amino acid profiles of the four species are very similar and comparable to the FAO reference protein, buth with a low content of methionine and cystine and a high content of lysine. The MEAA indices are between 81 and 84.98, without significant differences among the four species. Marine microalgae can be used as a potential SCP source.

[Abstract] Low hydrocarbon concentrations stimulated the growth of Tetraselmis suecica, whereas higher concentrations (200 ppm) inhibited growth. The content of chlorophyll a in this microalga was affected in a similar way. Crude oil had the most marked effects. Dispersant SEAKLIN-101-NT and mixtures of oil and SEAKLIN-101-NT did not show selective toxicity for the microalga, although inhibitory effects could be observed at high concentrations.