Enhancing rotifer Brachionus calyciflorus population growth with commercial probiotics

The effect of a commercial probiotic (NanoCrusta, Altacrusta, Mexico City, Mexico) on the growth performance of Brachionus calyciflorus Pallas, 1766, was evaluated. In a first approach, probiotics were supplied in four densities (2.0 × 10³, 1.1 × 10⁵, 2.1 × 10⁵ and 2.1 × 10⁶ cells/ml), alone and in combination with Chlorella vulgaris (1 × 10⁶ cells/ml). The test rotifer did not grow on the probiotic alone. However, when probiotics + C. vulgaris were added, the maximum densities (D_max; ind/ml) and population growth rates (r) observed were higher. In the second experiment, probiotics were supplied at five higher densities (2.1 × 10⁶, 4.2 × 10⁶, 8.5 × 10⁶, 1.7 × 10⁷ and 3.4 × 10⁷ cells/ml) with C. vulgaris and a control treatment with only C. vulgaris (probiotic‐free). Treatments supplied with probiotics between 2.1 × 10⁶ and 1.7 × 10⁷ cells/ml showed significantly higher D_max and r than the control treatment. The results showed a positive effect of probiotic bacteria when supplied with C. vulgaris. The best outcome showed a D_max 2.16 times and an r 1.63 times higher than the density of the control treatment. Growth rates were higher in the treatments with probiotics compared to the control. We conclude that application of NanoCrusta is feasible to improve B. calyciflorus production, but the effects need to be tested in larger scales.     

Evidence of clandestine harvest and failure of conservation policies for Argopecten purpuratus in the Rinconada Marine Reserve (Chile)

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Histological alterations in gills of shrimp Litopenaeus vannamei in low‐salinity waters under different stocking densities: Potential relationship with nitrogen compounds

Two experimental modules with different stocking densities (M1 = 70 and M2 = 120 shrimp /m²) were examined weekly over a culture cycle in tanks with low‐salinity water (1.9 g/L) and zero water exchange. Results showed survival rates of 87.7 and 11.9% in M1 and M2, respectively. Water temperature, pH, dissolved oxygen, electrical conductivity and chlorophyll a were not significantly (p > .05) different between modules. In contrast, the concentrations of nitrogen compounds were significantly (p < .05) different between modules, except nitrite‐N (M2 were 2.31 ± 1.38 mg/L N‐TAN, 0.18 ± 0.49 mg/L N‐NO₂^? and 6.83 ± 6.52 mg/L N‐NO₃^?; in M1: 0.97 ± 0.73 mg/L N‐TAN, 0.05 ± 0.21 mg/L N‐NO₂^? and 0.63 ± 0.70 mg/L N‐NO₃^?). When waters of both modules reached higher levels of ammonia and nitrite, histological alterations were observed in gills. The histological alterations index (HAI) was higher in M2 (5‐112) than in M1 (2‐22).     

Diet trials on tehuelche scallop Aequipecten tehuelchus (d'Orb) larvae

Laboratory spawned one week old veliger larvaeof the tehuelche scallop, Aequipectentehuelchus (D'Orb., 1846), were reared topedivelger stage under three different dietaryregimes in order to determine the best algalcombination under standard hatchery conditions.Veligers were cultured at mean densities of 2.7larvae/ml. Larval growth and survival wereassessed on larvae fed the following dietarytreatments: (1) Isochrysis galbana(T-Iso)+ Chaetoceros calcitrans, (2)Pavlova lutheri + C calcitrans, and (3)P. lutheri + I. galbana T-Iso +Ch. calcitrans. The highest growth rateswere detected on larvae fed diets includingP. lutheri.     

Histological effects on the kidney,spleen, and liver of Nile tilapia Oreochromis niloticus fed different concentrations of probiotic Lactobacillus plantarum

Tropical Animal Health and Production - The aims of this study were to evaluate the inclusion of different concentrations of Lactobacillus plantarum in Nile tilapia diet and to verify histological...     

Heat treatments and expansin gene expression in strawberry fruit

Heat treatments have been applied in fruit postharvest technology for insect disinfestations, decay control, ripening delay and modification of fruit responses to other stresses. Heat treatment affects several aspects of fruit ripening, such as ethylene production and cell wall degradation probably through changes in gene expression and protein synthesis. In this paper, strawberries (Fragaria × ananassa Duch., cv Camarosa) at 50–75% red stage of ripening were heat-treated at 45 °C during 3 h in an air oven and then stored at 20 °C for 0, 4, 18, 24 and 48 h. Fruit firmness was determined and the expression of a set of expansin genes (FaEXP1, FaEXP2, FaEXP4, FaEXP5 and FaEXP6) was analyzed. The firmness of treated fruit was higher than that of control fruit 24 h after treatment, though the differences disappeared after 48 h at 20 °C. The analysis by northern-blot indicated that heat treatments affected differently the expression of expansin genes. The expression of FaEXP1, FaEXP2 and FaEXP6 was lower in treated fruit during the following 24 h post-treatment. The lower expression of these expansin genes could contribute to delay softening after heat treatment.     

Modeling exurban development near Washington, DC, USA: comparison of a pattern-based model and a spatially-explicit econometric model

The development of private rural lands can significantly fragment landscapes, with potentially negative consequences on ecosystem services. Models of land-use trends beyond the urban fringe are therefore useful for developing policy to manage these environmental effects. However, land-use change models have been primarily applied in urban environments, and it is unclear whether they can adequately predict exurban growth. This study compared the ability of two urban growth models to project exurban development in north-central Virginia and western Maryland over a 24-year period. Pattern-based urban growth models (such as SLEUTH) are widely used, but largely mimic patterns that emerge from historic conditions rather than allowing landowner decision-making to project change. In contrast, spatially-explicit econometric models (such as the complementary log?Clog hazard assessed in this study) model landowner choices as profit-maximizing behavior subject to market and regulatory constraints. We evaluated the two raster-based models by comparing model predictions to observed exurban conversion at pixel and county scales. The SLEUTH model was more successful at matching the total amount of new growth at the county scale than it was at the pixel scale, suggesting its most appropriate use in exurban areas is as a blunt instrument to forewarn potential coarse-scale losses of natural resources. The econometric model performed significantly better than SLEUTH at both scales, although it was not completely successful in fulfilling its promise of projecting changes that were sensitive to policy. The lack of significance of some policy variables may have resulted from insufficient variation in drivers over our study area or time period, but also suggests that drivers of land use change in exurban environments may differ from those identified for urban areas.     

Effects of Pre-Stratification Storage Conditions on Black Walnut Seed Post-Stratification Germination Capacity

The objective of this work was to quantify changes in the germination capacity of Juglans nigra seeds following storage and then artificial stratification. Seeds were stored at 5 and –20 °C under 5% and 14% internal moisture content (IMC) for 0, 8, 10, and 12 months under conditions with oxygen or under vacuum. Germination percentage (GP) was affected by storage temperature, IMC, and storage period. Seeds stored with 5% IMC succeeded in germinating regardless of the temperature. Seeds stored with 14% IMC did not germinate (–20 °C) or germinated during storage (5 °C). The GP was reduced with the time of storage in seeds at –20 °C and 5% IMC and this effect was avoided in storage under vacuum. In conclusion, the germination capacity of black walnut seeds did not change for up to 12 months at low above-zero temperature and low IMC (5 °C, 5% IMC), being the most cost-effective alternative for long-term storage of black walnut seeds in commercial nurseries. Vacuum storage avoided the decrease of around 50% in average germination capacity of seeds stored for a year at –20 °C.