The economic viability for the production of live baits of White Shrimp (Litopenaeus schmitti) in recirculation culture system     

Leonardo Castilho de Barros  Oscar José Sallée Barreto  Marcelo Barbosa Henriques 《Aquaculture International》2014,22(6):1925-1935

Sportfishing is a growing segment in the fishing sector, which requires the supply of marine shrimps to meet the demand for live baits; however, the extraction of white shrimp from their natural habitat results in overfishing depleting natural stocks. Intensive cultivation in water recirculation system is a worldwide trend for shrimp farming, which, in addition to increasing productivity, minimizes the impact of effluent emission on the environment, reinforcing sustainability. This study analyzed the economic viability of establishing farms for the cultivation of white shrimp (Litopenaeus schmitti) in water recirculation system to meet the market demand of sportfishing for live baits. The indicators were used: internal rate of return (IRR), net present value (NPV) and payback period (PP). The best scenario, with 90 % survival rate and unitary selling prices of US$ 0.50, showed IRR 11.74 %, NPV (10 %) US$ 1,241.88 and PP 5.71 years, demonstrating financial risk for the production of live baits in the conditions proposed in this study.  相似文献   

Root proliferation in native perennial grasses of arid Patagonia,Argentina     

Yanina A TORRES  Carlos A BUSSO  Oscar A MONTENEGRO  Leticia ITHURRART  Hugo D GIORGETT  Gustavo RODRíGUEZ  Diego BENTIVEGNA  Roberto E BREVEDAN  Osvaldo A FERNáNDEZ  María M MUJICA  Sandra S BAIONI  José ENTíO  María N FIORETTI  Guillermo TUCAT 《干旱区科学》2014,(2):195-204

Pappophorum vaginatum is the most abundant C4perennial grass desirable to livestock in rangelands of northeastern Patagonia,Argentina.We hypothesized that(1)defoliation reduce net primary productivity,and root length density and weight in the native species,and(2)root net primary productivity,and root length density and weight,are greater in P.vaginatum than in the other,less desirable,native species(i.e.,Aristida spegazzinii,A.subulata and Sporobolus cryptandrus).Plants of all species were either exposed or not to a severe defoliation twice a year during two growing seasons.Root proliferation was measured using the cylinder method.Cylindrical,iron structures,wrapped up using nylon mesh,were buried diagonally from the periphery to the center on individual plants.These structures,initially filled with soil without any organic residue,were dug up from the soil on 25April 2008,after two successive defoliations in mid-spring 2007.During the second growing season(2008–2009),cylinders were destructively harvested on 4 April 2009,after one or two defoliations in midand/or late-spring,respectively.Roots grown into the cylinders were obtained after washing the soil manually.Defoliation during two successive years did reduce the study variables only after plants of all species were defoliated twice,which supported the first hypothesis.The greater root net primary productivity,root length density and weight in P.vaginatum than in the other native species,in support of the second hypothesis,could help to explain its greater abundance in rangelands of Argentina.  相似文献   

White spot syndrome virus (WSSV) infection and immunity responses in white shrimp (Litopenaeus vannamei) exposed to sublethal levels of metals     

Selene María Abad‐Rosales  Martín Gabriel Frías‐Espericueta  Oscar Guadalupe Romero‐Bernal  Rodolfo Lozano‐Olvera  Silvia Alejandra García‐Gasca  Leobardo Montoya‐Rodríguez  Domenico Voltolina 《Aquaculture Research》2019,50(3):758-764

To determine if exposure to a sublethal mixture of metals (Cd, Cu, Fe, Mn, Pb and Zn) increases susceptibility to White spot syndrome virus (WSSV) infection, Litopenaeus vannamei juveniles were fed WSSV‐infected shrimp tissues after 21 days of exposure to the metal mixture (WS‐MM treatment). Other treatments consisted of shrimp not exposed to metals and fed infected tissues (WS), and shrimp fed healthy tissues and exposed (MM) or not exposed to metals (C). The presence of viral DNA and inclusion bodies was detected at 32 hr postinfection (hpi) in the stomach epithelium of shrimp from the WS treatment, and eight hours later in shrimp from the WS‐MM treatment, possibly because of an initial negative effect of metals in viral replication. At 40 hpi, the severity of infection represented by the histopathological index increased in both WS and WS‐MM treatments, and values were higher in WS‐MM than in WS shrimp at the end of the experiment. From 56 hpi to the end of experiment, total hemocyte counts were lower in both WS‐MM and WS treatments, and concentrations were particularly low in WS‐MM shrimp. Conversely, phenoloxidase activity was higher in the WS‐MM treatment from 32 to 56 hpi, suggesting a possible role of the prophenoloxidase (proPO) system in the antiviral defense against WSSV. The presence of heavy metals at sublethal concentrations may increase shrimp susceptibility to WSSV; this is supported by a decrease in circulating hemocytes, an increase in the humoral response, and the development of a higher number of WSSV inclusion bodies.  相似文献   

Characterization of rice storage proteins by SE-HPLC and micro z-arm mixer   总被引：2，自引：0，他引：2  

Mria Oszvald  Sndor Tmskzi  Oscar Larroque  Eszter Keresztnyi  Lszl Tams  Ferenc Bks 《Journal of Cereal Science》2008,48(1):68-76

While the effect of protein content and composition on the functional properties of wheat flour is well studied, our knowledge on the same properties of rice flour is limited. This work was conducted to study the relationship between the dough mixing properties of flour from different rice cultivars and protein content and composition. An efficient sonication-based two-step extraction procedure was applied to isolate rice flour proteins. The size-exclusion HPLC (SE-HPLC) method, originally developed for separating wheat proteins, was applied with some minor modifications in order to study the size distribution of rice flour proteins. Four fractions were distinguished on the SE-HPLC profile and were further characterized by SDS-PAGE. Fractions I–III consisted of glutelins, while fraction IV contained albumin, globulin and prolamin proteins. When rice dough was characterized on the basis of mixing parameters in a micro z-arm mixer, significant differences were observed depending on the protein composition of the flour. Statistical analysis results indicated that the functional properties of the flour from different rice cultivars were associated with the amount of polymeric proteins and their size distribution.  相似文献   

Sensory,Mechanical, and Microscopic Evaluation of Staling in Low‐Protein and Gluten‐Free Breads     

Gene J. Ahlborn  Oscar A. Pike  Suzanne B. Hendrix  William M. Hess  Clayton S. Huber 《Cereal Chemistry》2005,82(3):328-335

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The filter-feeding bivalve Mytilus chilensis capture pelagic stages of Caligus rogercresseyi: A potential controller of the sea lice fish parasites     

Jaime A. Montory  Oscar R. Chaparro  Andres Averbuj  Luis P. Salas-Yanquin  Joseline A. Büchner-Miranda  Paulina Gebauer  Juan P. Cumillaf  Edgardo Cruces 《Journal of fish diseases》2020,43(4):475-484

The copepod Caligus rogercresseyi is an ectoparasite of several salmonid species. The pumping activity of filter-feeding molluscs could reduce the abundance of copepod dispersive larval stages in the water column. In this research, nauplius II and copepodid larvae of C. rogercresseyi were exposed to filtering mussels (Mytilus chilensis) of different sizes. These mussels were able to filter both larval stages, although they were more efficient in catching nauplius II. The fact that nauplius II were ingested more efficiently could be explained by their smaller size, lower swimming velocity (escape) and longer resting times between movements, when they were exposed to the influx of water around the inhalant area of the mussels. Larger mussels were more effective filtering C. rogercresseyi larvae due to their larger inhalant area and the related water influx. Additionally, the results suggest that larvae captured by the mussels can be incorporated into pseudofaeces or ingested and then released as part of the faeces. Thus, high concentrations of M. chilensis surrounding salmon farms may act as biological barriers, reducing the density of copepod dispersive larval stages and, thus, salmon infestations.  相似文献   

Identification of a mannose‐binding lectin‐like protein recognized by the anti‐CD25 antibody in haemocytes from Cherax quadricarinatus     

Mohamed Alí Pereyra  Oscar Vivanco‐Rojas  Jos Luis Snchez‐Salgado  Juan Jose Alpuche Osorno  Concepcin Agundis  Edgar Zenteno 《Aquaculture Research》2020,51(8):3119-3128

The crustacean haemolymph contains three main cell populations; however, it is not clear which mechanisms participate in the regulation of cells related to innate immunity. This work aimed to identify potential interleukin‐like receptors that could regulate cellular responses in Cherax quadricarinatus. By histochemical analysis with murine anti‐CD25 staining (targeting the α‐chain of the IL‐2 receptor), we identified that this antibody recognizes cytoplasmic granules in semigranular and granular haemocytes. In haemocytes stimulated with phorbol myristate acetate (PMA), increased fluorescence was observed in these cytoplasmic granules, whereas staining with a human IL‐2 antibody after stimulation with 1–10 ng/ml PMA revealed no overexpression of the receptor or oxidative burst in haemocytes. Two‐dimensional Western blot analysis of haemocyte lysates showed that anti‐CD25 identified a 27.4‐kDa protein with an isoelectric point (pI) of 7.7 and a 46‐kDa protein with a pI of 6.9. De novo sequencing of these proteins identified that they had 32% homology with a mannose‐binding lectin (MBL) from Pacifastacus leniusculus. Our results indicate that a mannose‐binding lectin‐like protein could exert a protective effect that prevents damage from other activated immune responses.  相似文献   

Response of the riverine fish community to the construction and operation of a diversion hydropower plant in central Chile     

Evelyn Habit  Mark C. Belk  Oscar Parra 《水产资源保护:海洋与淡水生态系统》2007,17(1):37-49

• 1. Chilean rivers have a large potential for hydropower development, and they also contain a unique native fish fauna with a high level of endemism. Several diversion hydropower plants have recently been constructed in Chile; however, the response of fish communities to these new hydropower plant designs is not well known.
• 2. Responses of native and non‐native fish to the construction and operation of a new hydropower plant that diverts water from two rivers were quantified. The Laja River is highly regulated and manipulated with three older (40 yr) dam‐based hydropower plants and irrigation diversions located upstream from the new facility. In contrast, the Rucúe River has no other hydropower facilities and is comparatively undisturbed.
• 3. Prior to construction, the Laja River had a fish community with lower species richness compared with the Rucúe River. The fish community structure in the Laja River was dramatically altered after the new hydropower facility began operation. On the other hand, in the Rucúe River, even though abundance of fish declined, there was less of a change in the total fish community structure. The fish community in the Rucúe River exhibited greater resistance to change compared with the Laja River.
• 4. The species most affected were the introduced salmonids and an endangered native species Percilia irwini.
• 5. Although diversion hydropower designs may have less impact than traditional dam‐based hydropower facilities, results of this study indicate that diversion hydropower structures can cause large changes in the fish community.

Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Vertical movements of coastal pike (Esox lucius)—On the role of sun basking     

Oscar Nordahl  Per Koch-Schmidt  Petter Tibblin  Anders Forsman  Per Larsson 《Ecology of Freshwater Fish》2020,29(1):18-30

Knowledge of patterns and drivers of the spatiotemporal distribution of top predatory fish is key to understand ecological dynamics and to successful management. Here, we integrated field and laboratory approaches to study vertical movements of pike (Esox lucius) in relation to season, light regimes and body temperature. We tagged pike from the Baltic Sea with data storage tags during spawning migration and retrieved them during migration the following years to obtain high-resolution data from full year of movements. The results showed seasonal and diel patterns of activity and body temperature that conformed to distinct patterns of crepuscular activity and diel vertical migrations. The latter manifested as two different patterns, either a stationary phase in the surface water during day followed by night-time in deeper water or vice versa. The occurrence of these two behaviours varied among individuals and within individuals among seasons. Diel vertical migration has previously not been described for this shallow-dwelling species, but was a common and consistent behaviour among individuals in this study. We suggest that the function of the daytime surface behaviour in pike is to increase body temperature through sun basking. This thermoregulatory role of surfacing was supported by the laboratory study where individuals sought the surface layer, exposed themselves to infrared light and thereby attained body temperatures in excess of ambient water. These results support sun basking as a mechanism for heat gain and further suggest that access to sunlight in the surface layer could be an important driver of vertical migrations.  相似文献   

Soil erosion evaluation in a small basin through the use of Cs technique     

Alfonso Bujan  Oscar J. Santanatoglia  Celio Chagas  Marcelo Massobrio  Mario Castiglioni  Marta Yaez  Hugo Ciallella  Jorge Fernandez 《Soil & Tillage Research》2003,69(1-2):127-137

Soil erosion significantly affects the most productive lands in Argentina, particularly the region called “Pampa Ondulada”. Quantification of the actual rates and patterns of soil loss is necessary for designing efficient degradation control strategies. The aim of this investigation was to gather using the ¹³⁷Cs technique a reliable set of data of erosion and sedimentation rates, in order to describe the long-term erosive landscape dynamic in a 300 ha basin representative for the “Pampa Ondulada” region of Argentina. The general topography of the basin is undulated with slopes gradients between 0 and 2.5% and slope lengths up to 800 m long. The main land use consisted in annual cropping under conventional tillage.For the soil erosion study in the basin the ¹³⁷Cs technique was used, which is based on the comparison between the ¹³⁷Cs inventories surveyed with a local reference ¹³⁷Cs profile. The sampling strategy was based on a multiple transect approach.The estimated mean soil erosion rates obtained applying Mass Balance Model 2 for the studied hillslopes ranged between −11.5 and −36 t ha⁻¹ per year and fitted the low and moderate erosion classes according to FAO. These values ranged beyond the admitted tolerance. Sedimentation was observed at the lower landscape positions probably related to changes from convex to concave slopes. The application of the ¹³⁷Cs technique in the studied basin proved to be a useful and sensible tool for assessing erosion/deposition rates. In areas with low topographic gradients like the Pampa Ondulada region, the slope length appears to be an important property for predicting spatial patterns of erosion rates.  相似文献