Growth Kinetics of Nanofrustulum Shiloi Under Different Mixing Conditions in Flat-plate Photobioreactor

Abstract Diatoms are the major group of microalgae which have been utilized by the potential applications as food industries, aquatic feeds, cosmetics, biofuels, and pharmaceuticals. In this study, current approaches were made in order to determine growth rate, biomass productivity, protein, carbohydrate, lipid and fatty acid composition for Nanofrustulum shiloi cultures using both aeration and mixing conditions in flat-plate photobioreactor (PBR). Physical (the intensity of aeration, mixing, light intensity etc.) and chemical (nutritional materials) factors are affecting the growth and bioproduct contents of a diatom. Biomass and lipid productivities of N. shiloi were measured as 31.29 and 36.9622±0.0598 mg L-1 day-1 in flat-plate PBR having the combination of aeration and stirring system, respectively. A slightly higher amount of saturated fatty acids was detected in PBR having only bubbling system while the increase of mono- and poly- unsaturated fatty acids were found in PBR having the combination of aeration and stirring system. Flat-plate PBR design was also investigated for improving not only biomass but also the lipid productivity of N. shiloi.

Microbialite-like structures in Cladophora sp. (Ulvophyceae) mats from a subtropical Andean basin: ecological implications / Estructuras de tipo microbialito en Cladophora sp. (Ulvophyceae) de una cuenca andina subtropical: implicaciones ecológicas

Abstract The solubility equilibrium of calcite is influenced by physicochemical, climatic and biological factors. Annual cycles of exceptionally prolonged drought, in conjunction with naturally occurring diffuse organic pollution, generate the unique conditions for the precipitation of lithified carbonate structures (microbialites). The aim of this article is to analyze the possible implications of calcite precipitation produced in mats of Cladophora sp. in an Andean subtropical basin, considering it is the first time this phenomenon is described for the region. We collected samples from selected sites at the Lules River Basin, in four sampling dates between the years 2003 and 2004, within a monitoring work of 15 years. Samples were analyzed using an electron microscope and X-ray diffraction analysis. We found that Gomphonema sp. attached to Cladophora sp. contributes to precipitation of calcite and formation of microbialite like structures, in the studied area. This work presents an initial discussion of the discovery of microbialites-like structures attached to Cladophora sp. mats in a subtropical Andean stream and the environmental conditions that lead to their production, as well as the possible ecological implications of these microbialites.(AU)

Resumen La fase sólida de las sales de los cuerpos de agua juega un papel importante en la concentración de los elementos mayoritarios. El equilibrio de solubilidad de la calcita está influenciado por factores fisicoquímicos, climáticos y biológicos. Los ciclos anuales de sequía excepcionalmente prolongada, junto con la contaminación orgánica difusa de origen natural, generan condiciones únicas para la precipitación de estructuras de carbonato litificado (microbialitos). El objetivo de este artículo es analizar las posibles implicaciones de la precipitación de calcita producida en Cladophora sp. en una cuenca subtropical andina, considerando que es la primera vez que se describe este fenómeno para la región. Recolectamos muestras en sitios seleccionados en la Cuenca del Río Lules, en cuatro fechas de muestreo entre 2003 y 2004, en el marco de un trabajo de monitoreo de quince años. Usamos red Surber para realizar los muestreos. Las muestras de algas, una vez libres de macroinvertebrados, se secaron y pesaron. Analizamos utilizando microscopía electrónica y difracción de rayos X. Encontramos que Gomphonema sp. unido a Cladophora contribuye a la precipitación de calcita y la formación de estructuras similares a microbialitos, en el área estudiada. Este trabajo presenta una discusión inicial sobre el descubrimiento de estructuras similares a microbialitos unidas a filamentos de Cladophora sp. en una cuenca andina subtropical y las condiciones ambientales que conducen a su producción, así como las posibles implicaciones ecológicas de lo mencionado anteriormente.(AU)

Response of phytoplankton to an experimental fish culture in net cages in a subtropical reservoir / Resposta do fitoplâncton ao cultivo experimental de peixes em tanques-rede em um reservatório subtropical

Abstract This study aimed to evaluate nutrients concentration and spatial-temporal changes in phytoplankton biovolume during an experimental fish culture in net cages in a lateral arm of Salto Caxias reservoir, Brazil. Two sampling stations were placed in the affected lateral arm and other two in a cageless lateral arm. Neither abiotic variables nor phytoplankton biovolume presented significant differences between the treatments. Only temporal changes were confirmed by the analysis performed. Both lateral arms were classified as oligotrophic, reflecting low influence of the net cages. Phytoplankton growth seems to be limited by nitrogen. Biovolume values were, in general, low and five major functional groups were recognized (E, F, G, K and P). In summer higher biovolume values were observed and representatives of Chlorophyceae and Cyanobacteria belonging to the functional groups F and K, respectively, were the most important. In winter phytoplankton was mainly composed by Bacillariophyceae taxa from P group. G group was also restricted to winter and E group occurred in winter and summer. The variations recorded in phytoplankton structure appear to have been mainly influenced by seasonal changes in temperature, precipitation and nutrients availability. The effects of net cages on the abiotic variables and phytoplankton biovolume appear to have been small, probably due to the small number of net cages employed and the system dilution capacity. However, a permanent monitoring of phytoplankton is recommended, since this environment has a carrying capacity, from which the trophic state may increase.

Resumo Este estudo objetivou avaliar alterações nas variáveis abióticas e no biovolume fitoplanctônico durante o cultivo experimental de peixes em tanques-rede em um braço lateral do reservatório de Salto Caxias, Brasil. Foram selecionadas duas estações de amostragem no braço com tanques-rede e outras duas em um braço sem tanques. As variáveis abióticas e o biovolume fitoplanctônico não apresentaram diferenças significativas entre os locais estudados. Apenas mudanças temporais foram confirmadas pelas análises utilizadas. Os dois braços laterais foram classificados como oligotróficos, refletindo a baixa influência dos tanques-rede. O crescimento do fitoplâncton parece ter sido limitado principalmente por nitrogênio. Os valores de biovolume foram, em geral, baixos e cinco principais grupos funcionais foram observados (E, F, G, K e P). No verão, os maiores valores de biovolume foram observados e representantes de Chlorophyceae e Cyanobacteria dos grupos funcionais F e K, respectivamente, se destacaram. No inverno, o fitoplâncton foi composto principalmente por táxons de Bacillariophyceae do grupo P. O grupo G também foi restrito ao inverno e o grupo E ocorreu no inverno e verão. As variações registradas na estrutura do fitoplâncton parecem ter sido principalmente influenciadas pelas mudanças sazonais de temperatura, precipitação e disponibilidade de nutrientes. Os efeitos dos tanques-rede sobre as variáveis abióticas e biovolume fitoplanctônico parecem ter sido pequenos, provavelmente devido ao pequeno número de tanques utilizados e a capacidade de diluição do sistema. Entretanto, o monitoramento permanente do fitoplâncton é recomendado, uma vez que este ambiente possui uma capacidade de suporte, a partir da qual o estado trófico pode aumentar.

Crecimiento y composición bioquímica de Thalassiosira pseudonana (Thalassiosirales: Thalassiosiraceae) bajo cultivo semi-continuo en diferentes medios y niveles de irradiancias / Growth and biochemical composition of Thalassiosira pseudonana (Thalassiosirales: Thalassiosiraceae) cultivated in semicontinuous system at different culture media and irradiances

Thalassiosira pseudonana is a marine Bacillariophyta commonly used as live feed in mariculture. The growth rate and biochemical composition of microalgae are highly influenced by environmental factors such as, irradiance and nutrient availability. The aim of this study was to investigate the influence of three irradiances (60, 120 and 180μE/m².s) and two culture media (Algal and Humus) on growth and biochemical composition of this diatom. The microalga was grown semicontinuously at a daily renewal rate of fresh media of 30%, 37‰ salinity, 25±1ºC and constant aeration (200mL/min). The cell densities (cel/mL) and contents of protein, lipid, carbohydrate, chlorophyll a, total carotenoids, and fatty acids, showed significant differences (p<0.05) between treatments. During steady-state phase, the maximal cell density, and lipid and carbohydrate contents were of 4.62x10(6)cel/mL, 20.3±2.28% and 16.6±2.43%, respectively, and were achieved in Humus medium at 180μE/m².s. Moreover, highest protein contents (45.0±5.05%) and total carotenoids (0.5±0.01%) were obtained in Algal medium at 180μE/m².s. Chlorophyll a (0.93±0.04%) was higher at low irradiances in Algal medium. In both media, the fatty acids unsaturation degree was lower with increasing irradiance, being eicosapentaenoic acid, 20:5 n-3 (EPA) most represented (6.20%) in Algal medium at 60μE/m².s. This strain of T. pseudonana showed multiple physiological responses to changes in culture conditions, and may be cultivated with an alternative medium, which reduced the operating costs and allowed a high nutritional biomass production value for animals under culture.

Thalassiosira pseudonana es utilizada como alimento en acuicultura, pero su valor nutricional está influenciado por las condiciones de crecimiento. Sistemas semicontinuos, en fase de estabilización, con tres irradiancias (60, 120 y 180μE/m².s) y dos medios de cultivo (Algal y Humus) fueron las condiciones en las que se determinó el crecimiento y componentes bioquímicos de T. pseudonana. En Humus a 180μE/m².s se obtuvieron las máximas densidades celulares (entre 3.86 y 4.62x10(6)cel/mL) y mayores concentraciones de lípidos y carbohidratos, con porcentajes de 20.3±2.28 y 16.6±2.43, respectivamente. A 180μE/m².s en Algal se observaron los mayores valores de proteínas (45.0±5.05) y carotenoides totales (0.5±0.01). El contenido de clorofila a fue favorecido por baja intensidad de luz, principalmente en Algal, con máximos de 0.9±0.04%. El grado de insaturación de los ácidos grasos disminuyó por incremento de la irradiancia en ambos medios, estando mayoritariamente representados por el ácido eicosapentaenoico, 20:5 n-3 (AEP), con porcentajes máximos (6.20%) en Algal a 60μE/m².s. Los resultados muestran múltiples respuestas fisiológicas de T. pseudonana frente a cambios en las condiciones de crecimiento, las cuales pueden ser aprovechadas para mejorar su valor nutricional como alimento de organismos cultivados, utilizando medios de cultivo alternativos, que disminuyan los costos en la producción microalgal.

Epiphytic diatoms associated with red mangrove (Rhizophora mangle) prop roots in Bahía Magdalena, Baja California Sur, Mexico

The first floristic inventory of benthic diatoms is provided for the Bahia Magdalena-Bahia Almejas lagoon system. Samplings were carried out during November of 1999. The oxydized samples were mounted permanently. Eighty six diatom taxa were identified, out of which 59 are new records for the Bahia Magdalena area, and 12 taxa are new for the Baja California peninsula. Taxa recorded previously as rare in other substrata are common or abundant on the epiphytic macroalgae of mangrove prop roots. Other species are mainly epipelic forms, while 24 are commonly found as tychoplankton in the area. Certain taxa appear to be characteristic of mangrove systems in general.

Se presenta el primer inventario florístico de diatomeas bénticas para el Sistema Lagunar Bahía Magdalena-Bahía Almejas. Se hicieron muestreos en noviembre de 1999. En las muestras oxidadas y montadas permanentemente, se identificaron 86 táxones, de los cuales 59 son nuevos registros para el área de Bahía Magdalena, y 12 son nuevos para la península de Baja California. Táxones previamente registrados como escasos en otros sustratos son comunes o abundantes sobre macroalgas epífitas de raíces primarias de mangle. Otras species son principalmente formas epipélicas, mientras que 24 son constituyentes comunes del ticoplancton del área. Ciertos táxones parecen ser característicos de sistemas de manglar en general.

Variacion espacial y temporal del fitoplancton de la laguna de unare (estado Anzoategui, Venezuela) noviembre 1988 – julio 1989 / Temporal and spatial variation of phytoplankton from Unare Lagoon (Anzoátegui state Venezuela) november 1988 – july 1989

Se estudió la variación espacial y temporal del fitoplancton en la Laguna de Unare desde noviembre 1988 hasta julio 1989. Las muestras de agua superficial se fijaron con formalina (10 por ciento) neutralizada con carbonato de sodio, para determinar la abundancia microalgal según el método de Utermõhl. Se encontró un aumento progresivo de la abundancia fitoplanctónica durante el período de estudio. Los valores promedios mensuales mínimos y máximos (8,63 x 102 y 4,53 x 105 cel. ml-1) se registraron en noviembre 1988 y junio 1989, respectivamente. Las diatomeas dominaron hacia el este de la Laguna (>50 por ciento del total de individuos) favorecidas por la penetración de agua marina y continental en esta zona. El resto de la laguna estuvo dominado por cianobacterias (>80 por ciento). Se encontraron diferencias altamente significativas (Fs = 28,736, p<0,001) con relación a la distribución temporal de los principales grupos de microalgas (cianobacterias, diatomeas, euglenofitas, dinoflagelados). Al inicio del estudio se observó la mayor variabilidad con relación a los grupos fitoplanctónicos, predominando las diatomeas. Estas fueron sustituidas por las cianobacterias que dominaron el fitoplancton hasta el final del período de estudio. Es importante mantener la conexión de la laguna con las aguas adyacentes para favorecer el desarrollo del fitoplancton y por ende la productividad primaria de este cuerpo de agua, la cual sustenta el resto de las comunidades del sistema.

Spatial and temporal changes in phytoplankton from Unare Lagoon were studied from November 1988 until July 1989. Water samples were fixed with neutral formaldehyde (10 percent) to determine microalgal abundance following Utermõhl´s method. Abundance increased continuously throughout the study period. The minimum and maximum average values (8.63 X 102 and 4.53 X 105 cell. ml-1) were measured in November 1988 and June 1989, respectively. Diatoms were the dominant group on the eastern side of the lagoon (>50 percent of the total number of organisms) and were favored by continental and marine water exchange. The rest of the lagoon was dominated by cyanobacteria (>80 percent of the total number of organisms). Highly significant temporal differences (Fs = 28.736, p<0.001) with respect to the distribution of the microalgal groups (cyanobacteria, diatoms, euglenophytas and dinoflagellates) were registered. High group variability occurred at the beginning of the study period when diatoms were dominant. It is important to maintain the connection between the lagoon and the adjacent waters in order to maintain phytoplankton growth and primary productivity which sustains the rest of the communities in this water body.

The use of pigment "fingerprints" in the study of harmful algal blooms

Along the Mexican coast, harmful algae blooms (HAB) have become more frequent, and therefore, there is an urgent need to establish monitoring programs to avoid the undesired consequences of HAB in human and natural ecosystems. In this work, we analyzed the pigment signatures and the species composition from phytoplankton samples to evaluate the utility of the specific pigment "fingerprints" in HAB monitoring programs. Vertical profiles from a coastal lagoon and temporal samples of a red tide occurring in a shrimp-culture pond and in a coastal zone were taken into consideration. Between 76% and 84% of dinoflagellate and diatom cell density was explained by their specific signature variation, in both vertical and temporal samples. Only the variation of zeaxanthin and the cyanobacteria Anabaena sp. showed a poor relationship, probably from difficulties in counting other cyanobacteria present in the samples examined with the microscopic method. These results suggest that inclusion of pigment analysis in the study and monitoring programs dealing with harmful algae would be very useful

A lo largo de las costas mexicanas, los florecimientos algales nocivos (FAN) se han vuelto cada vez mas frecuentes y por lo tanto, existe una necesidad urgente de establecer programas de monitoreo para evitar las consecuencias no deseadas por su desarrollo, sobre los ecosistemas naturales y el ser humano. En este trabajo, nosotros analizamos las huellas pigmentarias y la composición de especies de diversas muestras de fitoplancton para evaluar la utilidad que pueden representar estos pigmentos específicos o "huellas pigmentarias" en programas de monitoreo de florecimientos algales nocivos. Los perfiles verticales de muestras de fitoplancton de una laguna costera y muestras de mareas rojas que ocurrieron en un estanque de cultivo de camarón y en una laguna costera, fueron considerados en este estudio. Tanto en muestras verticales como en temporales, entre el 76% y 84% de la densidad celular de dinoflagelados y diatomeas fueron explicados por la variación de su huella específica, mientras que la variación de zeaxantina y la densidad de la cianobacteria Anabaena sp. mostró una relación pobre, la cual fue debida probablemente a la dificultad en el conteo que presenta este grupo al ser analizadas mediante un microscópico invertido. Estos resultados sugieren que la inclusión del análisis de las huellas pigmentarias en los programas del estudio y monitoreo de las algas nocivas sería de gran utilidad