Résumé
Prochilodus magdalenae es una especie de pez endémico de Colombia conocido por ser un importante recurso de interés comercial y para muchas comunidades relacionadas a las actividades pesqueras como actividad de sustento. No obstante, se ha observado un deterioro poblacional en ambientes naturales debido a factores tales como sobrepesca, fragmentación de ecosistemas, entre otros. Esto hace necesario caracterizar la diversidad genética de P. magdalenae en los sistemas reproductores de algunos centros piscícolas, que son usados para hacer repoblamientos en otras cuencas de Colombia y así proponer criterios técnicos y científicos que permitan el desarrollo de estrategias de manejo para la conservación de esta especie. Por lo anterior, en el año 2013 se recolectó tejido de aleta caudal de 1044 individuos en siete centros piscícolas, que fueron procesados en laboratorio y a través del uso de siete loci de microsatélites se evaluaron métricas genéticas tales como: heterocigosidad observada y esperada, número de alelos, índices de fijación, estadísticos F, agrupamiento bayesiano y AMOVA. Se encontró baja heterocigosidad observada, correlacionada con procesos de endogamia, que contrastan con los altos valores obtenidos en el índice de heterocigosidad esperada y la cantidad de alelos detectados en los sistemas de reproductores de P. magdalenae. Se detectó una moderada diferenciación genética entre centros piscícolas y se observó la existencia de tres grupos genéticos a través del agrupamiento bayesiano. Pese a la baja diversidad reportada con respecto a otras especies del mismo género, las poblaciones mantenidas en cautiverio de Bocachico tienen potencial para restaurar la diversidad de las poblaciones silvestres. Por lo que se sugiere que cada estación piscícola debe establecer lotes de reproductores por separado, en función de su información genética para que exista una congruencia entre los individuos liberados y aquellos que habitan en el medio natural.
Prochilodus magdalenae is an endemic fish species of Colombia known as an important resource of commercial interest for many communities related to fishing activities as a livelihood activity. However, population deterioration has been observed in natural environments due to factors such as overfishing, fragmentation of ecosystems, among others. This makes it necessary to characterize the genetic diversity of P. magdalenae in the productive systems of some fish farms, which are used to restocking in other basins of Colombia and, thus, to propose technical and scientific criteria that allow the development of management strategies for the conservation of this species. Therefore, in 2013, caudal fin tissue was collected from 1044 individuals in seven fish farms, which were processed in the laboratory. Through the use of seven microsatellites, genetic metrics such as: observed and expected heterozygosity, number of alleles, fixation indexes, F statistics, Bayesian grouping and AMOVA were evaluated. We observed low heterozygosity, correlated with inbreeding processes, which contrast with the high values obtained in the expected heterozygosity index and the number of alleles detected in P. magdalenae productive systems. A moderate genetic differentiation between fish centers was detected and the existence of three genetic groups was observed through the Bayesian analysis. Despite the low diversity reported regarding the others species of the same genus, populations held in Bocachico captivity have the potential to restore the diversity of wild populations. Therefore, it is suggested that each fish station should establish batches of breeders separately, based on their genetic information so that there is congruence between the released individuals and those that inhabit the natural environment.
Résumé
RESUMEN Las actividades de producción piscícola en el Lago de Tota, Boyacá aumentan las concentraciones de amonio y de nitrato, nutrientes que están acelerando los procesos de eutrofización. Entre las comunidades microbianas que regulan la entrada de nitrógeno alóctono figuran las bacterias nitrificantes y la determinación de su abundancia en los ecosistemas es una medida de bioindicación de contaminación. El objetivo del estudio fue cuantificar y caracterizar bioquímicamente las bacterias nitrificantes cultivables de la zona limnética del lago. Para medir la abundancia, se usó la técnica de número más probable (NMP). Las muestras fueron tomadas en los sectores Lago Chico y Lago Grande, en zonas limnéticas, con actividad piscícola y sin intervención. Se midieron variables físicas y químicas in situ y se determinó la concentración de nutrientes en el laboratorio. Las mayores cuantificaciones de bacterias nitrificantes, se registraron en el periodo de baja precipitación y en el área de influencia de piscicultura. El grupo de bacterias oxidantes de amonio (BOA) y oxidantes de nitritos (BON) fue menor en la zona central de lago Grande respecto a zonas de piscifactorías de Hato Laguna y El Túnel. Se obtuvieron 14 aislamientos de bacterias nitrificantes, identificando los géneros Nitrosomonas spp. y Nitrobacter spp. Los cambios en la abundancia de BOA, se relacionaron con la alcalinidad, mientras que los valores de BON, se correlacionaron con la conductividad eléctrica y el nitrógeno inorgánico disuelto. Una mayor abundancia de bacterias nitrificantes, se registró en las zonas limnéticas del lago, afectadas por la actividad piscícola, asociado al aumento de nutrientes disuelto en la columna de agua.
ABSTRACT Fish production activities in Lake Tota, Boyacá are increasing concentrations of ammonium and nitrate, nutrients that are accelerating eutrophication processes. Some of the microbial communities that regulate the entry of allochthonous nitrogen are nitrifying bacteria, and the determination of their abundance in ecosystems is a measure of pollution bioindication. The objective of the study was to quantify and biochemically characterize the cultivable nitrifying bacteria of the limnetic zone of Lake Tota. The most probable number technique (MPN) was used to measure abundance. The samples were taken in the Lago Chico and Lago Grande sectors, in limnetic areas with fish activity and without intervention. Physical and chemical variables were measured in situ and the concentration of nutrients in the laboratory was determined. The highest quantifications of nitrifying bacteria were recorded in the area of influence of fish farming. The group of ammonium oxidizing bacteria (BOA) and nitrite oxidants (BON) was smaller in the central area of Lago Grande compared to fish farms in Hato Laguna and El Túnel. 14 isolates of nitrifying bacteria were obtained, genera Nitrosomonas spp. and Nitrobacter spp. Changes in BOA abundance were related to alkalinity, while BON values correlated with electrical conductivity and dissolved inorganic nitrogen. A greater abundance of nitrifying bacteria was recorded in the lake's limnetic areas affected by fish farming activity, associated with the increase in nutrients dissolved in the water column.
Résumé
This paper presents a science metric study of parasites of fish farming in Brazil, including a significant review of the literature. The methodology used was based on researching articles in three different databases, carried out on May 2012: ISI (Institute for Scientific Information), SciELO (Scientific Electronic Library Online), and Google Academic. The number of articles on fish parasites is mounting (currently over 110), having much increased since 1995. However, the quantity is still low compared with the amount of papers on parasites of fish from natural environments. In Brazil, the farmed fish that have been studied the most are pacu, tilapia and tambaqui. Monogeneans represent the most prevalent group, followed by protozoa and crustaceans. The regions most researched were the southeast and south, making up 84% of the total literature. The main issue addressed in articles was pathology, followed by treatment and record. In conclusion, the treatment of parasitic diseases of farmed fish in Brazil is still incipient, highlighting the importance and usefulness of management practices to prevent the occurrence of health problems.
Este trabalho apresenta o estudo cienciométrico dos parasitos de peixes de cultivo do Brasil, incluindo significativa revisão da literatura. A metodologia adotada se baseou na pesquisa dos artigos feita no mês de maio de 2012 em três bancos de dados: ISI (Institute for Scientific Information), SciELO (Scientific Electronic Library Online) e Google Acadêmico. O número de artigos sobre parasitos de peixes cultivados está aumentando (autalmente mais de 110), havendo um crescimento a partir de 1995. Entretanto o número ainda é baixo se comparado ao número de artigos de parasitos de peixes de ambientes naturais. No Brasil, os peixes de cultivo mais estudados são pacu, tilápia e tambaqui. Os monogenéticos foram os grupos mais prevalente, seguido de protozoários e crustáceos. As regiões mais pesquisadass foram o sudeste e sul, perfazendo 84% da produção bibliográfica total. O principal assunto abordado nos artigos foi patologia, seguido por tratamento e registro. Conclui-se que os tratamentos das parasitoses de peixes de piscicultura no Brasil ainda são incipientes, ressaltando a importância e utilidade das boas práticas de manejo para evitar o aparecimento de problemas sanitários.