Variability of oceanographic and meteorological conditions in the northern Alboran Sea at seasonal,inter‐annual and long‐term time scales and their influence on sardine (Sardina pilchardus Walbaum 1792) landings     

Manuel Vargas‐Yez  Ana Girldez  Pedro Torres  María Gonzlez  Maria del Carmen García‐Martínez  Francina Moya 《Fisheries Oceanography》2020,29(5):367-380

Time series of European sardine (Sardina pilchardus) landings from 1962 and environmental variables from 1978 in the northern Alboran Sea are analysed. European sardine spawns in the northern Alboran Sea from mid‐autumn to late winter at a temperature range slightly higher than the one observed in the nearby Eastern North Atlantic and the North Western Mediterranean. Individuals hatched during autumn and winter are incorporated to the fishery during the following summer and autumn producing the maximum annual landings. These landings show both a decreasing long‐term trend and a strong inter‐annual variability. Although further research is needed, the warming trend of sea surface temperature and the decrease in upwelling intensity inferred from empirical orthogonal function (EOF) analyses could have some influence on the negative trends of sardine landings. The inter‐annual variability of sardine abundance seems to be related to the wind intensity at a local scale, the second principal component of the chlorophyll concentration and the sardine abundance during the preceding year. If the inter‐annual variability is considered, a linear model including these three variables with a one‐year time lag allows to explain 79% of the sardine landings variance. If the negative linear trend is also considered, the model explains 86% of the variance. These results indicate that the body condition of spawners, linked to the food availability during the preceding year, is the main factor controlling the recruitment success. The possibility of predicting sardine landings 1 year in advance could have important implications for fishery management.  相似文献   

Nitrogen fixation capacity and nodule occupancy by Bradyrhizobium japonicum and B. elkanii strains     

M. Hungria  L. H. Boddey  M. A. Santos  M. A. T. Vargas 《Biology and Fertility of Soils》1998,27(4):393-399

 In a previous study soybean Bradyrhizobium strains, used in Brazilian studies and inoculants over the last 30 years, and strains adapted to the Brazilian Cerrados, a region frequently submitted to environmental and nutritional stresses, were analyzed for 32 morphological and physiological parameters in vivo and in vitro. A cluster analysis allowed the subdivision of these strains into species Bradyrhizobium japonicum, Bradyrhizobium elkanii and a mixed genotype. In this study, the bacteria were analyzed for nodulation, N₂ fixation capacity, nodule occupancy and the ability to increase yield. The goal was to find a relationship between the strain groups and the symbiotic performance. Two strains of Brazilian B. japonicum showed higher rates of N₂ fixation and nodule efficiency (mg of N mg^–1 of nodules) under axenic conditions. These strains also showed greater yield increases in field experiments when compared to B. elkanii strains. However, no differences were detected between B. japonicum and B. elkanii strains when comparing nodule occupancy capacity. The adapted strains belonging to the serogroup B. elkanii SEMIA 566, most clustered in a mixed genotype, were more competitive than the parental strain, and some showed a higher capacity of N₂ fixation. Some of the adapted strains, such as S-370 and S-372, have shown similar N₂ fixation rates and nodulation competitiveness to two Brazilian strains of B. japonicum. This similarity demonstrates the possibility of enhancing N₂ fixing ability, after local adaptation, even within B. elkanii species. Differences in the DNA profiles were also detected between the parental SEMIA 566 and the adapted strains by analyses with the ERIC and REP-PCR techniques. Consequently, genetic, morphological and physiological changes can be a result of adaptation of rhizobia to the soil. This variability can be used to select strains capable of increasing the contribution of N₂ fixation to soybean nutrition. Received: 28 May 1997  相似文献   

Gene expression kinetics of the yellow head virus in experimentally infected Litopenaeus vannamei     

Yenelli Cedano‐Thomas  Jorge De La Rosa‐Vélez  Jean Robert Bonami  Francisco Vargas‐Albores 《Aquaculture Research》2010,41(10):1432-1443

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Patterns of commercial fish landings in the Loreto region (Peruvian Amazon) between 1984 and 2006     

Aurea Garcia  Salvador Tello  Gladis Vargas  Fabrice Duponchelle 《Fish physiology and biochemistry》2009,35(1):53-67

Patterns of commercial fish catches over the period from 1984 to 2006 were studied in the Loreto region and in Iquitos, which is the most important town of the region and the principal fish marketplace of the Peruvian Amazon. Despite important inter-annual variations, the overall fish landings have significantly increased in the region during this period. The same three species dominated the catches during the whole period (Prochilodus nigricans, Potamorhina altamazonica and Psectrogaster amazonica), making up about 62% of the catches. However, the number of species exploited by commercial fisheries increased considerably during the 22 years of this study (from about 21 species in 1984 to over 65 in 2006), although part of the difference may be accounted for by a better identification of individual species nowadays. At the same time, the large high-valued species, such as Arapaima gigas, Colossoma macropomum and Brachyplatystoma rousseauxii, declined significantly and were replaced by smaller, short-lived and lower-valued species. Catches of the silver Arahuana (Osteoglossum bicirrhosum) also declined significantly during the studied period, strengthening recent warnings about the species’ conservation status (Moreau and Coomes, Oryx 40:152–160, 2006). The relative proportions of the trophic groups (detritivores, omnivores and piscivores) remained relatively constant over the study period, but there were significant changes in the relative abundances of the species groups. The proportion of the dominant group, the Characiformes, which averaged about 81% of the catches, increased between 1984 and 2006, whereas the proportion of the Siluriformes and Perciformes remained constant. On the other hand, the proportion of Osteoglossiformes, represented only by two well known species (Arapaima gigas and Osteoglossum bicirrhosum), declined sharply during the same period. Important differences were observed between the landings of Iquitos and the landing of the whole Loreto region, indicating that conclusions drawn from the study of the Iquitos landings cannot be extrapolated to the whole landings of the Loreto region. The most important difference was the decreasing fish landings in Iquitos, whereas the total landings increased in the Loreto region at the same time. Potential causes of this phenomenon are discussed. Decreasing fish abundance around Iquitos (because of a higher fishing pressure) and a behavioural adaptation of fishermen to better law enforcement in Iquitos are likely explanations to be further investigated.  相似文献   

Environmental Quality and Cytogenotoxic Impact of the Waters of a Stream Receiving Effluents from Tannery Industry     

Viscardi  Michelle Hoffelder  da Silveira  Luís Felipe  Vargas  Luciano Kayser  da Silva  Fernanda Rabaioli  Beneduzi  Anelise 《Water, air, and soil pollution》2020,231(6):1-16

Water, Air, & Soil Pollution - Cu-based copper nanoclusters have generated a great deal of interest based on for their fluorescent and catalytic properties. However, as heterogeneous catalysts,...  相似文献   

Replacement of fish oil with vegetable oils in diets for jundiá (Rhamdia quelen Quoy and Gaimard 1824): effects on performance and whole body fatty acid composition   总被引：1，自引：1，他引：0  

Rodrigo Javier Vargas  Silvia Maria Guimarães de Souza  Alexandre Melo Kessler  & Sueli Regina Baggio 《Aquaculture Research》2008,39(6):657-665

The jundiá (Rhamdia quelen) is a siluriform with great potential for aquaculture in South America. Fish oil is a raw material in diets for fish. However, the fisheries that provide fish oil have reached their limit of sustainability. Thus, the use of alternative sources for this ingredient is primordial. The aim of this study was to evaluate the performance and body composition of the jundiá fed with different sources of the vegetable oils. Jundiá (1.0±0.2 g) were fed for 31 days with five isonitrogenous (37%) and isoenergetic (19 kJ g^?1) diets, in which the following oils were added: 50 g kg^?1 corn oil (CO), 50 g kg^?1 fish oil (FO), 50 g kg^?1 linseed oil (LO), 33.4 g kg^?1 fish oil and 16.7 g kg^?1 linseed oil (1/3LO), 16.7 g kg^?1 fish oil and 33.4 g kg^?1 linseed oil (2/3LO). The performance did not show differences between treatments. The final fatty acid profile and n‐3/n‐6 ratio of the fish were highly influenced by the diet. Fish‐fed diets with linseed and/or fish oil showed superior n‐3/n‐6 ratios to the minimal recommended by the World Health Organization; whereas fish fed diets with corn oil showed an inferior value. Albeit in the present study the commercial size of fish was not attained, these results show a clear tendency. The desaturation/elongation capacity was evidenced, in this species, for the first time. Linseed oil can be utilized as a substitute for fish oil in diets of jundiá without affecting their performance and for producing good‐quality fish. However, more studies are necessary to confirm these results for commercial size.  相似文献