In this study, five microalgal strains were isolated from Bahía de La Paz, Baja California Sur, Mexico and identified as Grammatophora sp., Navícula sp., Rhabdonema sp., Schizochytrium sp., and ...Nitzschia sp., and their evaluation as potential food for Artemia franciscana. The isolated strains were cultured outdoors and harvested after four days. Chaetoceros muelleri was cultured under laboratory conditions and used as control. The protein, lipid, and carbohydrate composition and the fatty acid profiles of the strains were determined by gas chromatography. To assess the effect of microalgal strains on A. franciscana, decapsulated cysts were cultured at outdoor conditions in 15 L containers. The experiment was conducted for twelve days. Samples from the five different feeding treatments were taken at the beginning and end of the experiment to assess number, size, and weight of Artemia larvae. Treatment with Rhabdonema sp. showed larvae with a lower percentage of polyunsaturated fatty acids (PUFAs) while Grammatophora sp. showed those with the greatest PUFA proportion, even more than those fed Chaetoceros muelleri (control). Larvae consuming Schizochytrium sp. had no docosahexanoic (DHA) nor eicosapentaenoic (EPA) fatty acid content. Growth and survival of A. franciscana did not show significant differences among feed treatments, except when it was fed Nitzschia sp., showing lower survival and dry weight. Treatment based on Schizochytrium sp. and Rhabdonema sp. had a greater A. franciscana size but reduced dry weight; additional tests including two or more algal species for every treatment should be carried out to determine the best yield.
•Schizochytrium sp. associated with Lactobacillus plantarum (T19 bacilli strain) can be an inoculum for starting biofloc systems for cultures of L. vannamei.•Schizochytrium sp. associated with ...Lactobacillus plantarum (T19 bacilli strain) prevents the growth of Vibrio spp. in biofloc systems for cultures of L. vannamei.•Schizochytrium sp. and Lactobacillus plantarum (T19 bacilli strain) can reduce shrimp diseases and environmental impact.
At present, the Pacific white shrimp Litopenaeus vannamei Boone, 1931, is one of the species with the greatest potential to be reared under biofloc Technology (BFT). Although BFT presents promising culture methods, some of these require improvements in efficiency by the use of native microalgae and bacteria (BFNO) as an alternative to commercial organism probiotics (BFCO). This experiment was developed using a culture system for the shrimp L. vannamei to a stocking density of 400 in./m3 for 44 days. Schizochytrium sp. and recently isolated Latobacillus plantarum (class: Bacilli), a probiotic strain (used as experimental biofloc), were incorporated to geomembrane tanks holding 28 m3 seawater to evaluate if these presented bioregulating effects influencing water quality and growth performance of L. vannamei. These microorganisms were compared with the BFCO. Results showed that both promoted bioflocs maintained optimal concentrations of total ammonium, nitrites, and nitrates for L. vannamei cultures. However, the BFCO required to be supplied every 10 days, whereas the experimental biofloc only required an initial stocking and maintenance of sodium carbonate levels >100 mg L−1 and pH > 7.5. Additionally, the load of Vibrio spp. in experimental biofloc was less than that observed for BFCO. Furthermore, the results of growth performance did not demonstrate differences between both treatments. Therefore, it is suggested that Schizochytrium sp. and the bacterial strain of L. plantarum should be used as initiator and basic constituents of the biofloc-based culture systems for L. vannamei, maintaining good water quality and avoiding periodical probiotic supplementation in cultures.
Biofloc systems in Pacific white shrimp (Penaeus vannamei) culture generate floccules that remove wastes, and hence, biofloc formation is promoted for shrimp production. This study evaluated the ...induction of biofloc formation using microalgae and probiotic bacteria in hyper-intensive Pacific white shrimp culture. The experiment was performed for six weeks in tanks (28,000 L each) stocked 350 ind m.sup.-3 and weight of 1400 + or - 30 mg. Three treatments were assessed: 1) with two diatoms: Grammatophora sp. and Navicula sp., 2) with Navicula sp., and 3) without diatoms. All treatments were added with Schizochytrium sp. and Lactobacillus fermentum TD19. The following parameters were monitored during culture: ammonium, nitrites, nitrates, environmental variables, floccules volume, microorganism presence, the bromatological composition of biofloc, and growth performance parameters of P. vannamei. Our results indicated that the three induced biofloc presented a similar volume (8.34 + or - 4.8 mL L.sup.-1) and ammonium concentration (<1.0 mg L.sup.-1). Treatment 1 generated floccules with the highest concentration of ciliates, rotifers, nematodes, lactic acid bacteria, and the lowest concentration of Vibrio spp. (1.2X10.sup.3 UFC mL.sup.-1), evidencing a significant difference in bromatological composition, with the highest protein and lipid values (28.12 + or - 0.50 and 22.44 + or - 0.80% biofloc dry weight, respectively) and the best feed conversion ratio (0.89). Based on these results, we suggest that Schizochytrium sp., L. fermentum, and two diatoms should be used to induce biofloc in a hyper-intensive culture of P. vannmaei in order to provide a supplementary nutritional intake, which can constitute an advantage to reduce commercial feed rations.
The in vitro digestibility of lipids from
Chaetoceros muelleri
that were cultured in Guillard medium (F/2) and agricultural fertilizer medium (AF/2) and performance index was examined in enzymatic ...extracts of
Litopenaeus vannamei
larvae. The highest enzymatic activity (EA) of lipases was observed in Zoea I (1.53 ± 0.14 EA/10 EU) and Mysis I (1.26 ± 0.01 EA/10 EU (EU are units of enzymatic activity)) when
C. muelleri
was grown in the F/2 medium. The highest concentration of the unsaturated fatty acids (UFAs) in
C. muelleri
was observed with F/2 medium (9.96 μg FA/10
6
cells), and the lowest was obtained with (AF/2) medium (6.68 μg FA/10
6
cells). The percentage of the total highly unsaturated fatty acids (HUFAs) in Zoea (18.23 %) and Mysis I (F/2 = 19.32 %, AF/2 = 20.25 %) larvae was similar between culture media. The performance indices (PI) of shrimp larvae (Zoea I to Mysis I) differed between culture media, with higher values of PI recorded with the F/2 medium-cultured algae (14.3 ± 1.1) with respect to the values with the AF/2 medium-cultured algae (8.0 ± 1.8). We concluded that due to the effect of the nitrogen source in AF/2 medium,
C. muelleri
cells have a lower HUFA content and
L. vannamei
larvae experience decreased lipid digestibility and performance index.
Microalgae cultures are receiving attention because of increasing biotechnological and biomedical production of active biomolecules. We evaluated various fertilizer-based culture media to scale up ...production of the marine microalga Phaeodactylum tricornutum for production of exocellular polysaccharides (EPS), soluble proteins, and cellular superoxide dismutase (SOD). The standard source of sodium nitrate was the same as that used in the synthetic f/2 culture medium and ammonium nitrate, urea, ammonium sulfate, and calcium nitrate as alternative sources of nitrogen. The maximum production of EPS was achieved in microalgae cells grown in the culture media containing 63 and 23% nitrogen from ammonium sulfate, and also in microalgae cells grown in the culture media containing 3% nitrogen from ammonium nitrate. The maximum production of cellular SOD was achieved in microalgae cells grown in the culture media containing 35 and 26% nitrogen from ammonium sulfate, and in the culture media containing 17% nitrogen from urea. The results suggest that it is possible to use a source of nitrogen, other than sodium nitrate, to scale up growth of P. tricornutum for production of EPS and SOD at reduced costs.
Se aislaron cinco cepas de microalgas de la BahÃa de La Paz, Baja California Sur, Mexico, identificadas como Grammatophora sp., Navicula sp., Rhabdonema sp., Schizochytrium sp., and Nitzschia sp., y ...su evaluación como alimento potencial para Artemia franciscana. Las cepas algales fueron aisladas, purificadas y cultivadas al exterior. Chaetoceros muelleri fue cultivada en condiciones de laboratorio y utilizada como control. El análisis bioquÃmico y el perfil de ácidos grasos correspondientes al cuarto dÃa de cultivo de las microalgas, se efectuó mediante cromatografÃa de gases. El experimento con Artemia franciscana se realizó al exterior por doce dÃas en tanques de 15 L. Se realizaron muestreos al inicio y al final del trabajo para determinar el incremento en talla, peso seco y sobrevivencia. El tratamiento con la microalga identificada como Rhabdonema sp. mostró larvas con menor porcentaje de ácidos grasos polinsaturados (PUFAs) mientras que aquellas alimentadas con Grammatophora sp. presentaron la mayor proporción, superando a las del control Chaetoceros muelleri. Con Schizothyrium sp. no presentaron los ácidos grasos docosahexanoico (DHA) y eicosapentanoico (EPA). La sobrevivencia obtenida al utilizarse las diferentes cepas no mostró diferencias significativas a excepción de la alimentación basada en Nitzschia sp. donde mostraron una sobrevivencia menor. Los tratamientos con base en Schizothyrium sp. y Rhabdonema sp. produjeron individuos de A. franciscana de mayor tamaño, pero se redujo el peso, por lo que se requieren mayores evaluaciones donde se incluyan dos o más especies de microalgas para determinar el mejor rendimiento.
In this study, five microalgal strains were isolated from Bahía de La Paz, Baja California Sur, Mexico and identified as Grammatophora sp., Navicula sp., Rhabdonema sp., Schizochytrium sp., and ...Nitzschia sp., and their evaluation as potential food for Artemia franciscana. The isolated strains were cultured outdoors and harvested after four days. Chaetoceros muelleri was cultured under laboratory conditions and used as control. The protein, lipid, and carbohydrate composition and the fatty acid profiles of the strains were determined by gas chromatography. To assess the effect of microalgal strains on A. franciscana, decapsulated cysts were cultured at outdoor conditions in 15 L containers. The experiment was conducted for twelve days. Samples from the five different feeding treatments were taken at the beginning and end of the experiment to assess number, size, and weight of Artemia larvae. Treatment with Rhabdonema sp. showed larvae with a lower percentage of polyunsaturated fatty acids (PUFAs) while Grammatophora sp. showed those with the greatest PUFA proportion, even more than those fed Chaetoceros muelleri (control). Larvae consuming Schizochytrium sp. had no docosahexanoic (DHA) nor eicosapentaenoic (EPA) fatty acid content. Growth and survival of A. franciscana did not show significant differences among feed treatments, except when it was fed Nitzschia sp., showing lower survival and dry weight. Treatment based on Schizochytrium sp. and Rhabdonema sp. had a greater A. franciscana size but reduced dry weight; additional tests including two or more algal species for every treatment should be carried out to determine the best yield.
Satellite-derived bathymetry methods over coastal areas were developed to deliver basic and useful bathymetry information. However, the process is not straightforward, the main limitation being the ...need for field data. The Self-calibrated Spectral Supervised Shallow-water Modeler (4SM) method was tested to obtain coastal bathymetry without the use of any field data. Using Landsat-8 multispectral images from 2013 to 2016, a bathymetric time series was produced. Groundtruthed depths and an alternative method, Stumpf's Band Ratio Algorithm, were used to verify the results. Retrieved (4SM) vs groundtruthed depths scored an average r² (0.90), and a low error (RMSE = 1.47 m). 4SM also showed, over the whole time series, the same average accuracy of the control method (40%). Advantages, limitations and operability under complex atmosphere and water column conditions, and high and low-albedo bottom processing capabilities of 4SM are discussed. In conclusion, the findings suggest that 4SM is as accurate as the commonly used Stumpf's method, the only difference being the independence of 4SM from previous field data, and the potential to deliver bottom spectral characteristics for further modeling. 4SM thus represents a significant advance in coastal remote sensing potential to obtain bathymetry and optical properties of the marine bottom.
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