Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Larval feeding studies of both ornamental and consumable fish species are important for formulating successful management, and culture strategies for conservation purposes. In the present study, we evaluated prey selectivity for the tropical gar Atractosteus tropicus in the larval stage (first 8 weeks) using the zooplankton Artemia fransiscana, Daphnia pulex and Moina macrocopa as prey following the hypothesis that prey selection of the fish species is related not only to prey species preferences but to the difference in prey densities present in the environment. Functional responses were tested at prey densities of 0.2, 0.5, 1.0, 2.0, 4.0 and 8.0 ind. mL-1 and analyzed using Manly’s α. For prey selectivity, we used the three zooplankton species at three different densities. In these two experiments the fish larvae were allowed to feed for 45 min. To quantify feeding behavior (encounters, attacks, captures, ingestions, rejections) we used a density of 1 ind. mL-1 using each prey species based on 10 minutes of direct observation. Our results showed a functional response Type II for A. tropicus preying mostly on A. franciscana and M. macrocopa. The Manly’s α index showed that M. macrocopa and A. franciscana are the most preys selected. The values for encounters for the three prey species were relatively constant during the eight weeks. Encounter values for the cladocerans were low in comparison to A. franciscana; however, high success in capture and ingestion was observed for all prey species used. Our results from the functional response experiments supports the hypothesis that A. tropicus is an active predator presenting a functional response of a carnivorous fish and the shift in prey selection suggests that even at low prey availability, A. tropicus is able to manipulate and feed on zooplankton of wide range in size. Also, according to our results, we suggest the use of a mix of A. franciscana and M. macrocopa to feed A. tropicus in culture systems in concentrations ≈ 2 ind. mL-1 during the first 3 weeks of age and then shift to M. macrocopa from the 4 week. Our results, in conjunction with studies on the survivorship of the juveniles would aid in conservation efforts and improve the production of gars in aquaculture.

Valeriana L. genus is represented in Venezuela by 16 species, 9 of these are endemic of Venezuelan Andes growing in high mountains at 2800 masl. In this investigation, four species were analyzed in order to determine the main secondary metabolites and antimicrobial activity of extracts obtained from aerial parts of Valeriana parviflora, V. rosaliana, V. triplinervis and V. phylicoides. Alkaloids, flavonoids, tannins, sterols, triterpenoids and saponins were qualitatively observed in all methanolic extracts tested. The color intensity or a precipitate formation was used as analytical response to these tests. Antimicrobial activity was evaluated against Gram positive, Gram negative bacterial strains and yeast, using disc diffusion method. N-hexane extracts of V. triplinervis and V. rosaliana showed the highest efficiency against Staphylococcus aureus, exhibiting inhibition zones of 16 mm and 15 mm; MIC (Minimal Inhibition Concentration) values were observed at 116 mg/mL and 150 mg/mL, respectively. Dichloromethane and methanolic extracts of V. triplinervis and methanolic extract of V. rosaliana showed a rather moderate activity (MIC between 200 to 316 mg/ml) but a very weak antibacterial activity was observed in V. phylicoides and V. parviflora extracts (MIC > 420 mg/mL). None of the extracts assayed in this investigation showed any activity against Candida albicans and Candida krusei. Statistical analysis showed no significant differences on the different polarity extracts assayed with respect to antimicrobial activity against S. aureus (P > 0.10), however it was observed significant differences between the Valeriana species analyzed (P < 0.10) in relation to the minimal inhibitory concentration (MIC). 

The sea anemone Condylactis gigantea is an ecologically important member of the benthic community in coral reefs of the tropical Atlantic, and displays two morphotypes with respect to the color in their tentacular tips: the green tip morphotype and the pink/purple tip morphotype. Although some molecular and ecological differences have been found between these morphotypes, no other morphological distinctions have been reported, and currently both are still considered a single taxonomic species. In the present study, we perform an exploration on the variability in the size of cnidae between these two morphotypes and performed statistical analyses to compare the 10 categories of cnidae from specimens hosted in the Cnidarian Collection of Gulf of Mexico and Mexican Caribbean, of the Universidad Nacional Autónoma de México, which were previously collected in several coral reefs localities of the Yucatán Peninsula. Results reveal no significant variation in cnidae size between the two morphotypes, but significant variations were found within each morphotype. In addition, we update the composition of the cnidom of C. gigantea, and the utility of the size of cnidae to distinguish between morphotypes or closely related species is discussed.

Amazonian fish assemblages are typically high in species diversity and trophic complexity. Stable isotopes are valuable tools to describe the trophic structure of such assemblages, providing useful information for conservation and ecological management. This study aimed at estimating the relative contribution of the different basal carbon sources to the diet of primary consumer fishes (herbivores and detritivores), and determining the trophic position (TP) of the dominant fishes from each trophic guild (herbivores, detritivores, invertivores and piscivores). For this purpose we analyzed stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) in potential food sources, and muscle tissue of fishes in five oxbow lakes located in the floodplain of River Ichilo, Bolivia. Terrestrial plants and C3 aquatic macrophytes were the major carbon source contributing to the diet of herbivorous fishes, whereas particulate organic matter (POM) contributed more to the diet of detritivore fishes. In general, C4 aquatic macrophytes contributed little to the diet of herbivores and detritivores. However, we found a relatively high contribution of C4 macrophytes (28 %) to the diet of the herbivores Mylossoma duriventre and Schizodon fasciatus. We found a good agreement between our estimated TP values and the trophic group assigned based on diet composition from literature. The herbivore M. duriventre was at the bottom of the food web, being the baseline organism (TP = 2). The remaining primary consumers (herbivores and algivore/detritivores) exhibited relatively high TP values (2.3 - 2.9), probably due to their opportunistic feeding behavior. Omnivore/invertivore species studied displayed TP values near the 3.0 value expected for secondary consumers. Piscivore fishes were at the top TP, with TP values varying from 3.3 (Serrasalmus spilopleura and Serrasalmus rhombeus) to 3.8 (Pseudoplatystoma fasciatum). The fact that detritivore fishes, the most abundant food source for piscivores, occupy relatively high TPs determines that food chains in these particular Amazonian floodplains are longer than previously thought.

Having been a relatively modest partner in the Penibetica mining boom of 19th century that was based on lead ores and small scale production, mining in the Sierra de Lujar was, during a large part of the second half of 20th, a matter of one of the leading companies in the field as Peñarroya. Regarding this last phase, this paper focuses on company «management» of labour, related to its production strategies in specific geological conditions and socioeconomic context. In interaction with this, analysis also looks at workers answers and emphasizes about the dynamic of reciprocal adaptations which is revealed by the evolution of working conditions, its changes and continuities. Better times for miners came quite late and were short-lived. Case study extends to the very recent past historian’s reflection on the role of mining industry in contemporaneous Spain «development».

Marble extraction has been carried out constantly in Almería since the first centuries of our era till nowadays. In the 1980s a radical change regarding its extraction, processing and marketing took place. It was then when the marble industrial district emerged and was characterised with a great dynamism. This chapter analyzes the generation process of the industrial district as well as its evolutionary dynamics. Previous features of a mining agglomeration are described. It is shown how the setting up of the industrial district took place and the latest version of its configuration is depicted with the presence of a local multinational (Cosentino). This case study confirms how mining activities can evolve into the dynamics of an industrial district; it also shows the components which give the industrial district a great resilience.

This article analyses the contribution of the State to the expansion of wine cooperatives in Spain over the course of the twentieth and the early years of the twenty-first centuries. We examine the legislation that created the institutional framework for their development, and the role of the State in providing both financial and technical assistance. We show that the State’s contribution was critical to differences not just in the rate of their expansion but also in their distribution throughout the main winegrowing regions of Spain. Finally, we assess the consequences of State intervention on their overall performance, highlighting a lack of involvement as the main reason for the slow development of wine cooperatives in the early period, but also the dangers of excessive State intervention later.

During the Francoist period, many representatives of the French political and economic milieu underlined the big differences that, in their view, separated Catalonia from the rest of Spain. Did these perceptions have real consequences in the field of economic relations? We are particularly interested in testing if France had more intense or somehow specific relations —in the spheres of technology, investment, trade, tourism and migration— with Catalonia than with Spain as a whole. We examine also if the French agents used the same strategies towards Madrid and Barcelona, if they shared trading and financial partners and if the Catalan demands for autonomy affected the French attitude. In attempting to answer these questions, we will base on a great geographical and sectoral variety of sources.

ter the discovery of the existence of phosphate in Western Sahara by the geologist Manuel Alía Medina in the year 1945, Spain ordered the National Company of Mining Investigation (Enadimsa) to carry through the investigation and exploitation of the phosphate mining area of Western Sahara with the purpose of providing phospated fertilizers to the national industry. In this job my objective is to analyze the evolution of this first stage of the investigation and taking the mineral deposit into account through the study of the documents of both companies appointed by the INI: Enadimsa and the National Company of Mining of the Sahara S.A (Enminsa). In this paper, I hold that the lack of a clear policy defined by the state and the lack of finance, delayed the exploitation of this mineral deposit until the late years of Franco’s regime.

The longevity of family businesses is one of the most significant questions in this research from the point of view of knowing the risks and factors that contribute to their long-term survival. We highlight the role of family cohesion as a facilitator of such longevity. Cohesion enables succession, because when problems arise those family businesses and business families that are cohesive are more likely to survive in the long term. The research focuses on SMEs, where the relationship between family and business is more relevant than in large family corporations. In this paper, we illustrate the role of cohesion or its absence in the evolution of a family business – Persán – and how periods of family unity are typically accompanied by phases of business growth and success, as well as how conflict among owning families can slow businesses to a crawl and even lead them to bankruptcy.