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11.
Josafat J Ojeda-Ramírez Jorge Iván Cáceres-Puig José M Mazón-Suástegui & Pedro E Saucedo 《Aquaculture Research》2008,39(1):18-23
Three Pavlova species were evaluated for their nutritional value as diets for growth and survival of the Cortez oyster Crassostrea corteziensis spat during late‐nursery cultivation at a hatchery. Microalgae were provided as monospecific diets (Pavlova salina, P. sp. C50 and P. sp. C53) and in binary combinations of diets 1+2, 1+3 and 2+3 at 80–90 × 103 cells mL?1 for 21 days. Juveniles experienced high survival rates and grew well with all dietary treatments, but binary diets yielded greater survival and growth of spat. From the three binary treatments, Diet 6 (P. sp. C50 and P. sp. C53) promoted significantly (P<0.001) fastest growth of juveniles in shell height (0.19 mm day?1), shell length (0.14 mm day?1), total wet weight (0.04 g day?1) and dry weight of meat biomass (0.024 g day?1). For all shell dimensions, the lowest growth rates occurred with Diets 2 (P. sp. C56 alone) and 3 (P. sp. C50 alone). These results highlight the importance of testing microalgal diets for bivalve spat rather than just relying on published nutritional values. 相似文献
12.
This investigation examined the effects of live prey availability on growth and survival of Sepia officinalis. Two independent experiments, comprising two feed rations each, were performed, using adequate prey size. In the first experiment, cuttlefish hatchlings were fed live mysids, Paramysis nouvelli [(feed ratio I (fr I)], at 15% body weight per day (bw day?1) (fr I15) and 30% bw day?1 (fr I30). In the second experiment, juvenile cuttlefish were fed live Atlantic ditch shrimp, Paleomonetes varians (fr II), under the same experimental design. In both experiments, the final mean weight, feeding rate and instantaneous growth rate were higher when animals were fed feed ratio fr II15 and fr II30 (30% bw day?1). The results indicate that prey availability influenced weight gain, irrespective of the prey used, during the first 2 months of cuttlefish life cycle. This effect seems to be more noticeable when a certain limit of prey is achieved. For cuttlefish fed fr II, the optimal prey density is thought to be under 2.5 g prey L?1 (i.e. 14 shrimp L?1). Results indicate that cuttlefish can withstand prey densities up to 120 mysids L?1 for cuttlefish up to 3 weeks old and 19 shrimps L?1 for cuttlefish up to 6 weeks old. 相似文献
13.
Ella Vázquez‐Domínguez Andrea Bolongaro‐Crevenna Adolfo Sánchez Carlos Rosas 《Aquaculture Research》2008,40(1):91-102
As a function of the water quality provided by square, circular and oval experimental ponds, the growth, survival and oxygen requirements in epibenthic postlarvae of Farfantepenaeus aztecus were analysed in relation to their routine metabolism and apparent heat increment. Temperature, oxygen concentration, pH and salinity were measured daily in two experimental ponds of each shape. The postlarvae oxygen consumption during two 24‐h cycles, their growth, physiological condition and survival and the productivity in the ponds were estimated. Low values of pH, oxygen concentration and phytobenthos productivity, and reduced postlarvae relative growth and survival were observed in the square ponds. We suggest that the latter results from a deficient water circulation related to the effect of the pond's shape on dissolved oxygen levels and, consequently, on growth and survival. The postlarvae routine metabolism, including feeding, varied between 1.91 and 2.25 mg O2 h?1 g?1 wet weight, whereas the minimum oxygen concentration needed in the ponds is approximately 4.25 mg O2 L?1. These conditions were achieved in the oval ponds concurrent with higher survival and growth values, in which individuals distributed randomly, for which we suggest that oval‐shaped ponds could be the most adequate for the culture of this and other penaeid species. 相似文献
14.
This investigation compared the effects of using two binders of no nutritional value, lignosol and agar, and the binding method,
microbinding and microcoating, on the growth of juvenile Atlantic ditch shrimp, Palaemonetes varians, and rockpool prawn, Palaemon elegans. Shrimp were fed one basal diet which varied solely in binder type and method of inclusion (Diet A, with lignosol added by
microbinding, Diet B, with agar added by microbinding, and Diet C with lignosol added by microcoating) for a period of 45 days.
At the end of the experiment significant differences in the final wet weight were found between shrimps fed Diet A and Diet
C and between shrimps fed Diet B and Diet C (P < 0.001), but no significant differences were found between Diet A and Diet B (P > 0.05). These results were verified for both species. Significant differences were found between the linear regression slopes
of the three tested diets for P. varians (F
3,411 = 3.41; P < 0.04), and for P. elegans (F
3,431 = 10.51; P < 0.0003). Palaemon elegans grew faster than P. varians and at the end of the experiment significant differences were found between the final wet weight of the two species (F
3,842 = 48.17, P < 0.0001). The growth parameters analysed, weight gain (WG), thermal-unit growth coefficient (TGC), and food conversion rate
(FCR) were always higher for P. elegans. Results indicate that use of either lignosol or agar, added to the diet by microbinding, is advisable. 相似文献
15.
Pedro Domingues Ana Ferreira Lorenzo Marquez José P. Andrade Nelda López Carlos Rosas 《Aquaculture International》2008,16(3):215-229
The effects of feeding three natural frozen diets, grass shrimp (Palaemonetes sp.), crayfish (Procambarus clarkii) and fish (Sardina pilchardus) and two semi-humid artificial diets (based on fish powder) to mature cuttlefish, Sepia officinalis, were analysed. Growth and feeding rates (GR and FR, % BW day−1), food conversions (FC, %), and total protein and lipid composition of the diets were determined. Digestive gland to body
weight ratio and absorption efficiency were calculated for each diet. Cuttlefish fed shrimp and crayfish grew larger (1.5
and 1.1% BW day−1, respectively) compared to the other diets. Shrimp promoted the highest FC, followed by crayfish, and sardine. The highest
FR was obtained for cuttlefish fed crayfish (8.4% BW day−1). Although both artificial diets were accepted, none produced growth. A positive correlation (r = 0.96) between cuttlefish ingestion rate and digestive gland weight was obtained. Some cannibalism occurred among cuttlefish
fed the artificial diets during the last week of the experiment. According to the results obtained, P. clarkii could be used as an alternative prey to shrimp for rearing adult mature (>50 g) S. officinalis. 相似文献
16.
Ricardo Rocha Milou Groenenberg Paulo E. D. Bobrowiec Mar Cabeza Jorge M. Palmeirim Christoph F. J. Meyer 《Landscape Ecology》2017,32(1):31-45
Context
Habitat loss, fragmentation and degradation are widespread drivers of biodiversity decline. Understanding how habitat quality interacts with landscape context, and how they jointly affect species in human-modified landscapes, is of great importance for informing conservation and management.Objectives
We used a whole-ecosystem manipulation experiment in the Brazilian Amazon to investigate the relative roles of local and landscape attributes in affecting bat assemblages at an interior-edge-matrix disturbance gradient.Methods
We surveyed bats in 39 sites, comprising continuous forest (CF), fragments, forest edges and intervening secondary regrowth. For each site, we assessed vegetation structure (local-scale variable) and, for five focal scales, quantified habitat amount and four landscape configuration metrics.Results
Smaller fragments, edges and regrowth sites had fewer species and higher levels of dominance than CF. Regardless of the landscape scale analysed, species richness and evenness were mostly related to the amount of forest cover. Vegetation structure and configurational metrics were important predictors of abundance, whereby the magnitude and direction of response to configurational metrics were scale-dependent. Responses were ensemble-specific with local-scale vegetation structure being more important for frugivorous than for gleaning animalivorous bats.Conclusions
Our study indicates that scale-sensitive measures of landscape structure are needed for a more comprehensive understanding of the effects of fragmentation on tropical biota. Although forest fragments and regrowth habitats can be of conservation significance for tropical bats our results further emphasize that primary forest is of irreplaceable value, underlining that their conservation can only be achieved by the preservation of large expanses of pristine habitat.17.
Ahlem Zrig Jorge F. S. Ferreira Foued Hamouda Taieb Tounekti Samy Selim Soad Al Jaouni 《Arid Land Research and Management》2019,33(3):297-320
Salinity reduces plant biomass and may lead to death when severe. To cope with the negative effects of this stress, plant species present specific physiological or biochemical responses. In this work, we hypothesized that spraying salt-stressed thyme leaves with K+ and Ca2+ could mitigate the negative effects of salinity on plant growth and metabolism. To test this hypothesis, we grew thyme plants under salinity stress for two and four weeks before applying foliar sprays. Also, to test the effect of stress relief, treated plants were allowed two weeks of recovery after four weeks of salt stress. In general, after two and four weeks of salinity stress, the leaf fresh weight of thyme plants was reduced by 31 and 43%, respectively. Salinity also decreased the relative water content, water, and osmotic potentials and led to ion imbalances and nutrient deficiencies. Salinity altered concentration of some essential oils, but leaf antioxidant contents remained fairly stable, except for a significant increase for plants under NaCl?+?KCl two weeks after treatment. Our results indicated that stressed plants accumulated significantly more soluble sugars and amino acids in comparison with the control. Foliar sprays with KCl and CaCl2 reversed the negative effects of salinity on plant biomass and induced the accumulations of compatible solutes. Moreover, concentrations of some essential oils and gallic acid increased in sprayed plants, but these effects were dependent on the type and duration of the treatment. Overall, spraying leaves with K+ and Ca2+ was able to mitigate salinity stress in Thymus vulgaris even during the recovery period. 相似文献
18.
San-José Miriam Arroyo-Rodríguez Víctor Jordano Pedro Meave Jorge A. Martínez-Ramos Miguel 《Landscape Ecology》2019,34(5):1069-1080
Landscape Ecology - Landscape structure can affect seed dispersal, but the spatial scale at which such effect is maximized (scale of effect, SoE) is unknown. We assessed patterns and predictors of... 相似文献
19.
Intensive tillage for annual crop production may be affecting soil health and quality. However, tillage intensity effects on biological activities of volcanic-derived soils have not been systematically investigated. We evaluated the effects of three different tillage practices on some biological activities of an Ultisol from southern Chile during the third year of a wheat–lupin–wheat crop sequence. Treatments were: no tillage with stubble burning (NTB), no tillage without stubble burning (NT) and conventional tillage with disk-harrowing and stubble burning (CT). Biological activities were evaluated in winter and summer at 0–200 mm and at three soil depths (0–50, 50–100 and 100–200 mm) in winter. Total organic C and N were significantly higher under no-tillage systems than CT. In general, NT increased C and N of microbial biomass in comparison with CT, especially in winter. Microbial biomass C was closely associated with microbial biomass N (r = 0.986, P < 0.05); acid phosphomonoesterase (r = 0.999, P < 0.05); β-glucosidase (r = 0.978, P < 0.05), and others. Changes in biological activities occurred mainly in the upper soil layer (0–50 mm depth) in spite of the short duration of the experiment. Biological activities could be used as practical biological indicators to apply the more appropriate management systems for increasing soil sustainability or productivity. 相似文献
20.
Do Carmo Barbosa Mendes De Vasconcelos M Bennett RN Rosa EA Ferreira Cardoso JV 《Journal of agricultural and food chemistry》2007,55(9):3508-3516
Chestnut (Castanea sativa) is an important basic food in rural diets and a major starch crop used in a similar way to potatoes. Chestnuts are a fundamental economic resource in the "chestnut regions" not only for the fruit but also for the chestnut wood. Chestnuts have become increasingly important with respect to human health, for example, as an alternative gluten-free flour source. Chestnuts are also a rich source of other beneficial compounds, but there have been few studies on the composition during processing. In this study, we analyzed the chemical composition of three Portuguese cultivars at different stages of industrial processing. The chestnut cultivars were Longal, Judia, and Martaínha. All three cultivars had high moisture contents but were low in ash, crude fat, and crude protein contents, with high starch and low fiber contents. The free amino acid contents, including various essential amino acids, varied depending on the cultivar. All three cultivars also had a significant content of polyphenolics with gallic acid; ellagic acid was predominant among hydrolyzable and condensed tannins. Many of these compounds are known to exert significant positive effects on human health. The one-way analysis of variance for fresh chestnut shows significant differences among the three cultivars for most of the studied parameters. The same statistical analysis applied to each one of the two cultivars (Judia and Longal) sampled for the four processing steps analyzed indicates a significant effect of this factor in practically all of the constituents. On the other hand, the two-way analysis of variance shows that, besides the residual, the processing step and the interaction cultivar x processing step were the factors that more contributed for the total variation observed in the constituents analyzed, while the contribution of cultivar was much less significant. 相似文献