Sulfated Polysaccharides from Chaetoceros muelleri: Macromolecular Characteristics and Bioactive Properties.

In the present study, a culture of Chaetoceros muelleri, a cosmopolitan planktonic diatom microalga present in the Sea of Cortez, was established under controlled laboratory conditions. A sulfated polysaccharide (CMSP) extraction was carried out from the biomass obtained, resulting in a yield of 2.2% (w/w of dry biomass). The CMSP sample was analyzed by Fourier transform infrared spectroscopy, showing bands ranging from 3405 to 590 cm-1 and a sulfate substitution degree of 0.10. Scanning electron microscopy with elemental analysis revealed that the CMSP particles are irregularly shaped with non-acute angles and contain sulfur. High-performance liquid chromatography coupled to a dynamic light-scattering detector yielded molecular weight (Mw), polydispersity index (PDI), intrinsic viscosity [η], and hydrodynamic radius (Rh) values of 4.13 kDa, 2.0, 4.68 mL/g, and 1.3 nm, respectively, for the CMSP. This polysaccharide did not present cytotoxicity in CCD-841 colon cells. The antioxidant activity and the glycemic index of the CMSP were 23% and 49, respectively, which gives this molecule an added value by keeping low glycemic levels and exerting antioxidant activity simultaneously.

Biofilm-forming capacity of two benthic microalgae, Navicula incerta and Navicula sp., on three substrates (Naviculales: Naviculaceae)

Benthic microalgae have the natural capacity to adhere to a diversity of fixed submerged substrates to form biofilms, which have important roles not only in natural ecosystems, but also in aquaculture systems. An experimental investigation was performed to assess the biofilm-forming capacity of two microalgae (Navicula incerta and Navicula sp.) on three different substrates (plastic net, fabric, and wood) under controlled temperature and light conditions. The substrates were arranged on curtains suspended from a wood stick, into plastic aquariums (45 L in capacity) filled with filtered marine water enriched with F/2 medium. The trial was carried out until the exponential growing phase of the microalgae was reached. After that, the incorporated biomass was gravimetrically calculated, and its biochemical composition was determined by standard methods. The greatest amount of incorporated dry matter was observed for Navicula sp. on fabric and the lowest was observed for wood. The highest number of cells associated with the biofilm was obtained for Navicula sp. on the plastic net (1.24 x 109 cells/m2), while the lowest was recorded for Navicula sp. on the wood (1.43 x 108 cells/m2). Significant differences in organic matter were found among the substrates, with the highest values for N. incerta on the fabric (3.22 g/m2) and the lowest for Navicula sp. on the wood (0.02 g/m2). The best biochemical profiles among the formed biofilms were observed for N. incerta on the plastic net and Navicula sp. on the fabric. The plastic net was considered the best substrate because of the stability of the biofilm and the easiness of harvesting the biomass.

Las microalgas bentónicas tienen la capacidad natural de adherirse a diversos sustratos fijos sumergidos para formar biopelículas, las cuales tienen roles importantes no solo en ecosistemas naturales sino también en sistemas de producción acuícolas. Se llevó a cabo una investigación experimental para evaluar la capacidad formadora de biopelículas de dos microalgas bentónicas (Navicula incerta y Navicula sp.) en tres diferentes sustratos (malla plástica, tela y madera), bajo condiciones controladas de temperatura y luz. Los sustratos fueron arreglados a manera de cortinas suspendidas de un tubo de PVC dentro de acuarios de plástico (45 L de capacidad) con agua marina enriquecida con el medio F/2. El experimento se llevó hasta que la fase de crecimiento exponencial de la microalga fue alcanzada. Posteriormente la biomasa incorporada fue calculada gravimétricamente, y su composición bioquímica fue determinada por métodos estándar. La mayor cantidad de materia seca se observó para N. incerta en el sustrato de tela y la menor se encontró en el de madera. El mayor número de células asociadas a la biopelícula fue registrado para Navicula sp. en malla plástica (1.24 x 109 cel/m2), mientras que el menor se encontró para Navicula sp. en madera (1.43 x 108 cels/m2). Diferencias significativas en cuanto a materia orgánica se encontraron entre los sustratos y las especies, con valores más altos para N. incerta en tela (3.22 g/m2) y más bajos para Navicula sp. en madera (0.02 ± 0.05 g/m2). Los mejores perfiles bioquímicos para las biopelículas correspondieron a las formadas por N. incerta sobre malla plástica y Navicula sp. sobre tela. La red de plástico se consideró el mejor sustrato debido a la estabilidad de la biopelícula y la facilidad para cosechar la biomasa.

Effects of a co-culture of marine algae and shrimp (Litopenaeus vannamei) on the growth, survival and immune response of shrimp infected with Vibrio parahaemolyticus and white spot virus (WSSV).

In aquaculture, fighting infectious diseases is a necessity. This study measured the immuno-stimulating effect of live macroalgae consumption on Litopenaeus vannamei against Vibrio parahaemolyticus and WSSV infection in two independent bioassays. Shrimps and macroalgae were cultivated in a co-culture with two species of macroalgae separately (Gracilaria vermiculophylla and Dictyota dichotoma), and later, shrimp were infected with V. parahaemolyticus. In another bioassay, shrimp and macroalgae (G. vermiculophylla, D. dichotoma and Ulva lactuca) were grown and subsequently infected with WSSV. For both bioassays, survival after 120 h was determined, the total hemocyte count (TCH) was measured and the activity of superoxide dismutase (SOD) and catalase (CAT) in tissue were measured. The results indicate that the use of macroalgae in co-culture with L. vannamei provides a nutritional benefit that achieves higher growth than the control organisms, as well as improvements of the ammonium concentration and immune response after infection with V. parahaemolyticus and WSSV. A better immune response was obtained in organisms cultured with macroalgae in both bioassays at a ratio of 1.6-1.9 for organisms infected with bacteria and 1.4 to 1.6 times for organisms infected with the virus. In turn, the enzymatic activity of SOD and CAT were higher in the treated organisms relative to the controls in both experiments.

From microbes to fish the next revolution in food production.

Increasing global population and the consequent increase in demand for food are not a new story. Agroindustrial activities such as livestock help meet this demand. Aquaculture arose decades ago and revolutionized the agroindustrial activity as a significant food generator. However, like livestock, aquaculture is based on finite resources and has been accused of being unsustainable. Abandoning aquaculture is not an option considering the food, foreign exchange, and employment it generates, and therefore must be reinvented. Among the many alternatives suggested to make aquaculture more sustainable, microorganisms have been highlighted as a direct food source for cultured fish and crustaceans, a strategy that promises to revolutionize aquaculture by eliminating waste. Considering waste, as part of a cycle, it can increase stock densities and reduce emissions of contaminants and operational costs.

Navicula sp. Sulfated Polysaccharide Gels Induced by Fe(III): Rheology and Microstructure.

A sulfated polysaccharide extracted from Navicula sp. presented a yield of 4.4 (% w/w dry biomass basis). Analysis of the polysaccharide using gas chromatography showed that this polysaccharide contained glucose (29%), galactose (21%), rhamnose (10%), xylose (5%) and mannose (4%). This polysaccharide presented an average molecular weight of 107 kDa. Scanning electron microscopy (SEM) micrographs showed that the lyophilized Navicula sp. polysaccharide is an amorphous solid with particles of irregular shapes and sharp angles. The polysaccharide at 1% (w/v) solution in water formed gels in the presence of 0.4% (w/v) FeCl3, showing elastic and viscous moduli of 1 and 0.7 Pa, respectively. SEM analysis performed on the lyophilized gel showed a compact pore structure, with a pore size of approximately 150 nm. Very few studies on the gelation of sulfated polysaccharides using trivalent ions exist in the literature, and, to the best of our knowledge, this study is the first to describe the gelation of sulfated polysaccharides extracted from Navicula sp.

Effects of methanolic macroalgae extracts from Caulerpa sertularioides and Ulva lactuca on Litopenaeus vannamei survival in the presence of Vibrio bacteria.

Macroalgae are potentially excellent sources of highly bioactive secondary metabolites that are useful for the development of new functional ingredients. This study was conducted to determine whether methanolic extracts from Caulerpa sertularioides and Ulva lactuca macroalgae might be possible alternatives for the prevention of shrimp vibriosis, which is caused by Vibrio parahaemolyticus and Vibrio alginolyticus. Macroalgae extracts prepared with methanol as the solvent were evaluated for antibacterial activity with the microplate method. The extracts' effects on the mortality of juvenile Litopenaeus vannamei were evaluated at doses of 150 and 300 mg L(-1). Two independent assays for V. parahaemolyticus and V. alginolyticus were performed. The methanolic extract of C. sertularioides exhibited activity against V. parahaemolyticus and V. alginolyticus, and it had minimal inhibitory concentrations of <1000 and < 1500 µg mL(-1), respectively. L. vannamei mortality in the presence of both The methanolic extract of C. sertularioides exhibited activity against V. parahaemolyticus and V. alginolyticus, and it had minimal inhibitory concentrations of <1000 and <1500 µg mL(-1), respectively. and V. alginolyticus bacteria significantly decreased after treatment with 300 mg L(-1) C. sertularioides methanolic extract.

Enhancing Ecoefficiency in Shrimp Farming through Interconnected Ponds.

The future development of shrimp farming needs to improve its ecoefficiency. The purpose of this study was to evaluate water quality, flows, and nitrogen balance and production parameters on a farm with interconnected pond design to improve the efficiency of the semi-intensive culture of Litopenaeus vannamei ponds. The study was conducted in 21 commercial culture ponds during 180 days at densities of 30-35 ind m(-2) and daily water exchange <2%. Our study provides evidence that by interconnecting ponds nutrient recycling is favored by promoting the growth of primary producers of the pond as chlorophyll a. Based on the mass balance and flow of nutrients this culture system reduces the flow of solid, particulate organic matter, and nitrogen compounds to the environment and significantly increases the efficiency of water (5 to 6.5 m(3) kg(-1) cycle(-1)), when compared with traditional culture systems. With this culture system it is possible to recover up to 34% of the total nitrogen entering the system, with production in excess of 4,000 kg ha(-1) shrimp. We believe that the production system with interconnected ponds is a technically feasible model to improve ecoefficiency production of shrimp farming.

Bio-filtration capacity, oxygen consumption and ammonium excretion of Dosinia ponderosa and Chione gnidia (Veneroida: Veneridae) from areas impacted and non-impacted by shrimp aquaculture effluents.

Mollusks are some of the most important, abundant and diverse organisms inhabiting not only aquatic ecosystems, but also terrestrial environments. Recently, they have been used for bioremediation of aquaculture effluents; nevertheless, for that purpose it is necessary to analyze the capacity of a particular species. In this context, an experimental investigation was developed to evaluate the performance of two bivalves C. gnidia and D. ponderosa, collected from areas with or without shrimp aquaculture effluents. For this, the filtration capacity (as clearance rate) as well as the oxygen consumption and ammonia excretion rates were measured following standard methods. The clearance rate was significantly higher for D. ponderosa from impacted areas, when com- pared to C. gnidia, from both areas. Contrarily, the oxygen consumption was greater for C. gnidia from impacted areas compared to D. ponderosa from both areas. The same tendency was observed for the ammonia excretion with the highest rates observed for C. gnidia from impacted areas, whereas no differences were observed among D. ponderosa from both areas. The results suggest that both species developed different strategies to thrive and survive under the impacted conditions; D. ponderosa improved its filtration efficiency, while C. gnidia modified its oxygen consumption and ammonia excretion. We concluded that both species, and particularly D. ponderosa, can be used for bioremediation purposes.

Bio-filtration capacity, oxygen consumption and ammonium excretion of Dosinia ponderosa and Chione gnidia (Veneroida: Veneridae) from areas impacted and non-impacted by shrimp aquaculture effluents / Bio-filtración, consumo de oxígeno y excreción amoniacal de Dosinia ponderosa y Chione gnidia (veneroida: veneridae), en áreas impactadas y no impactadas por efluentes de granjas camaroneras

Mollusks are some of the most important, abundant and diverse organisms inhabiting not only aquatic ecosystems, but also terrestrial environments. Recently, they have been used for bioremediation of aquaculture effluents; nevertheless, for that purpose it is necessary to analyze the capacity of a particular species. In this context, an experimental investigation was developed to evaluate the performance of two bivalves C. gnidia and D. ponderosa, collected from areas with or without shrimp aquaculture effluents. For this, the filtration capacity (as clearance rate) as well as the oxygen consumption and ammonia excretion rates were measured following standard methods. The clearance rate was significantly higher for D. ponderosa from impacted areas, when com- pared to C. gnidia, from both areas. Contrarily, the oxygen consumption was greater for C. gnidia from impacted areas compared to D. ponderosa from both areas. The same tendency was observed for the ammonia excretion with the highest rates observed for C. gnidia from impacted areas, whereas no differences were observed among D. ponderosa from both areas. The results suggest that both species developed different strategies to thrive and survive under the impacted conditions; D. ponderosa improved its filtration efficiency, while C. gnidia modified its oxygen consumption and ammonia excretion. We concluded that both species, and particularly D. ponderosa, can be used for bioremediation purposes.

Los moluscos son algunos de los organismos más importantes, abundantes y diversos que habitan no solo ecosistemas acuáticos sino también terrestres. Recientemente ellos han sido utilizados para la biorremediación de efluentes acuícolas; para este propósito, es necesario conocer la capacidad de especies particulares que funcionan como biorremediadores. En este contexto, se evaluó la eficiencia de filtración (medida como tasa de clarificación), así como las tasas de consumo de oxígeno y excreción amoniacal en los bivalvos D. pon- derosa y C. gnidia recolectados en áreas impactadas y no impactadas por efluentes de granjas camaroneras. La tasa de clarificación fue mayor para D. ponderosa procedente de áreas impactadas, comparada con la de C. fluctifraga en las dos áreas de recolecta. Contrariamente, la tasa de consumo de oxígeno fue superior en C. gnidia en las áreas impactadas al compararla con organismos de áreas no impactadas y con D. ponderosa de las dos áreas de recolecta. La tasa de excreción amoniacal siguió una tendencia similar con valores más altos para C. gnidia en áreas impactadas, mientras que no se observaron diferencias para D. ponderosa entre las áreas de recolecta. Los resultados sugieren que ambas especies desarrollan diferentes estrategias para adaptarse y sobrevivir bajo condiciones de impacto; D. ponderosa mejora su eficiencia de filtración y C. gnidia modifica su consumo de oxígeno y excreción amoniacal. Se concluye que ambas especies, pero sobre todo D. ponderosa pueden ser utilizadas con propósitos de biorremediación.

Effluents of shrimp farms and its influence on the coastal ecosystems of Bahía de Kino, Mexico.

The impact on coastal ecosystems of suspended solids, organic matter, and bacteria in shrimp farm effluents is presented. Sites around Bahía de Kino were selected for comparative evaluation. Effluent entering Bahia Kino (1) enters Laguna La Cruz (2). A control site (3) was outside the influence of effluents. Water quality samples were collected every two weeks during the shrimp culture period. Our data show that the material load in shrimp farm effluents changes biogeochemical processes and aquatic health of the coastal ecosystem. Specifically, the suspended solids, particulate organic matter, chlorophyll a, viable heterotrophic bacteria, and Vibrio-like bacteria in the bay and lagoon were two- to three-fold higher than the control site. This can be mitigated by improvements in the management of aquaculture systems.

Filtration and clearance rates of Anadara grandis juveniles (Pelecypoda, Arcidae) with different temperatures and suspended matter concentrations

The mangrove cockle Anadara grandis (Broderip and Sowerby, 1829) is a potential candidate for aquaculture and for bioremediation of aquaculture effluents in the tropical and subtropical coastal areas of the eastern Pacific Ocean. Laboratory-produced spat are available, but there is no information on their responses to the range of environmental conditions to which they might be subject during the growth cycle. The aim of this study was to evaluate the filtration and clearance rates ofA. grandis spat (shell length 9.50+/-0.37 mm) with a food concentration (7.5 mgxl(-1)) at four different temperatures (22, 25, 28 and 31 degrees C, with pH=7.5+/-0.2 and O2 concentration of 6.4+/-0.5 mgxl(-1); experiment one); and with a temperature (25 degrees C) and five concentrations of suspended matter (from 7.5 to 29 mgxl(-1) and pH and O2 values of 7.9+/-0.2 and 6.8+/-0.4 mgxl(-1); experiment two). Filtration and clearance rates were highest at 25 degrees C and significantly different (p<.05) from those obtained at 22, 28 and 31 degrees C; the clearance rates had the same tendency but the differences were not significant (p>.05). In the second experiment filtration increased according to the amount of food available, but there were no significant differences (p>.05) between 7.5 and 11 mgxl(-1) and from 22.4 to 29 mgxl(-1). The trend was similar for clearance, and in this case significant differences were found (p<.05) between 7.5, 22.4 and 29 mgxl(-1). Filtration at 31 degrees C was close to 80% at the optimum temperature of 25 degrees C, which indicates that A. grandis is a good candidate for tropical aquaculture. Clearance increased with high concentrations of suspended solids, but the production of biodeposits could be a source of environmental concern. Therefore, the possibility of using this species for bioremediation of aquaculture effluents should be studied with larger specimens and at higher seston concentrations.

La almeja Anadara grandis (Broderip and Sowerby, 1829) es un candidato potencial para la acuicultura y la biorremediación de efluentes acuícolas en las áreas costeras tropicales y subtropicales del océano Pacífico oriental. Se dispone de semilla producida en laboratorio, sin embargo no hay información sobre sus respuestas a los intervalos de las condiciones ambientales a las cuales puede estar sujeta durante el periodo de crecimiento. El objetivo de este estudio fue evaluar las tasas de filtración y de clarificación de semilla de A. grandis (largo de la concha= 9.50±0.37 mm) con una concentración de alimento (7.5 mg∙l-1) y cuatro diferentes temperaturas (22, 25, 28 y 31 °C con pH= 7.5±0.2, concentración de O2 de 6.4±0.5 mg∙l-1; experimento uno); y con una temperatura (25 °C) y cinco concentraciones de material suspendido (de 7.5 a 29 mg∙l-1 y niveles de pH y O2 de 7.9±0.2 y 6.8±0.4 mg∙l-1, experimento dos). Las tasas de filtración y de clarificación fueron máximas a 25 °C y significativamente diferentes (p<.05) de las obtenidas a 22, 28 y 31 ºC; la tasa de clarificación presentó la misma tendencia, pero las diferencias no fueron significativas (p>.05). En el segundo experimento, se registró un incremento de la filtración, de acuerdo a la concentración de alimento, pero sin diferencias significativas (p>.05) en los intervalos 7.5 a 11 mg·l-1 y 22.4 a 29 mg·l-1. La clarificación mostró la misma tendencia y en este caso se encontraron diferencias significativas (p<.05) entre 7.5, 22.4 y 29 mg·l-1. La cantidad de sólidos ingeridos a 31 °C representó más del 80% de la filtración a 25 °C, que indica que A. grandis es un buen candidato para la acuicultura tropical. Con altas concentraciones de sólidos la clarificación aumentó, pero se notó una producción de pseudoheces que pudieran ser fuente de problemas ambientales, por lo cual se sugiere que la posibilidad de utilizar esta especie para la biorremediación de efluentes debería ser investigada con...

Filtration and clearance rates of Anadara grandis juveniles (Pelecypoda, Arcidae) with different temperatures and suspended matter concentrations.

The mangrove cockle Anadara grandis (Broderip and Sowerby, 1829) is a potential candidate for aquaculture and for bioremediation of aquaculture effluents in the tropical and subtropical coastal areas of the eastern Pacific Ocean. Laboratory-produced spat are available, but there is no information on their responses to the range of environmental conditions to which they might be subject during the growth cycle. The aim of this study was to evaluate the filtration and clearance rates ofA. grandis spat (shell length 9.50+/-0.37 mm) with a food concentration (7.5 mgxl(-1)) at four different temperatures (22, 25, 28 and 31 degrees C, with pH=7.5+/-0.2 and O2 concentration of 6.4+/-0.5 mgxl(-1); experiment one); and with a temperature (25 degrees C) and five concentrations of suspended matter (from 7.5 to 29 mgxl(-1) and pH and O2 values of 7.9+/-0.2 and 6.8+/-0.4 mgxl(-1); experiment two). Filtration and clearance rates were highest at 25 degrees C and significantly different (p<.05) from those obtained at 22, 28 and 31 degrees C; the clearance rates had the same tendency but the differences were not significant (p>.05). In the second experiment filtration increased according to the amount of food available, but there were no significant differences (p>.05) between 7.5 and 11 mgxl(-1) and from 22.4 to 29 mgxl(-1). The trend was similar for clearance, and in this case significant differences were found (p<.05) between 7.5, 22.4 and 29 mgxl(-1). Filtration at 31 degrees C was close to 80% at the optimum temperature of 25 degrees C, which indicates that A. grandis is a good candidate for tropical aquaculture. Clearance increased with high concentrations of suspended solids, but the production of biodeposits could be a source of environmental concern. Therefore, the possibility of using this species for bioremediation of aquaculture effluents should be studied with larger specimens and at higher seston concentrations.