La ictiofauna como bioindicadora de la cuenca del Aº Langueyú

Objetivos: Evaluar la calidad ambiental de la cuenca del arroyo Langueyú y analizar su relación con la estructura y composición de la comunidad de peces, para poder inferir a partir de los peces la condición ambiental, y utilizar esta información como una herramienta de diagnóstico ambiental de este sistema fluvial.Área: Ciencias Biológicas, Ambiente y Salud

¿El pejerrey puede causar cambios estructurales en un ecosistema?

La laguna Del Estado se secó circunstancialmente a comienzos de la década de 1960. El aislamiento hidrológico superficial del ambiente impidió la recolonización masiva de peces. En octubre de 1997 se realizó un diagnóstico de situación a partir del cual se sembraron alevinos de pejerrey Odontesthes bonariensis a baja densidad (250 ind/ha); en la primavera del 2001 se repitió el muestreo para evaluar resultados. El trabajo tiene como objetivo comparar ambos momentos e inferir el rol del pejerrey en las modificaciones observadas en el sistema. En 1997 la costa poseía un cinturón de macrófitas sumergidas; las emergentes se distribuían en parches en toda la superficie. La transparencia del agua resultó elevada. El macrozooplancton fue escaso, con presencia de calanoideos. No se capturó pejerrey y las otras especies de peces resultaron poco numerosas. En 2001 no se observaron macrófitas sumergidas. La transparencia del agua disminuyó a la mitad. El macrozooplancton fue abundante; se capturaron dos clases de edad (2000 y 1999) de dientudo Oligosarcus jenynsi y sabalito Cyphocharax voga, especies ausentes en el muestreo previo. Las diferentes variables biológicas del pejerrey manifiestan una excelente colonización. Se establecieron las dietas de los peces para dilucidar las principales interacciones tróficas presentes. La predación del macrozooplancton por parte del pejerrey, pudo beneficiar el fitoplancton en detrimento de las macrófitas sumergidas y contribuir al pasaje de la laguna de aguas «claras» a «turbias». El elevado número de zooplanctontes puede estar influenciado por el momento de muestreo. La presencia de un ambiente despoblado potenció el restablecimiento del pejerrey. El reciente y exitoso ingreso de O. jenynsi y C. voga se facilitó por la diferente oferta ambiental. El dientudo cumple el rol de superpredador, ocupando la cima de la nueva red trófica. La adaptación del sabalito, de régimen algófago, estaría vinculada al mayor desarrollo logrado por su comunidad presa. La presencia del pejerrey habría actuado como disparador de los cambios ecosistémicos evidenciados, produciendo un efecto cascada sobre otros componentes

¿El pejerrey puede causar cambios estructurales en un ecosistema?

La laguna Del Estado se secó circunstancialmente a comienzos de la década de 1960. El aislamiento hidrológico superficial del ambiente impidió la recolonización masiva de peces. En octubre de 1997 se realizó un diagnóstico de situación a partir del cual se sembraron alevinos de pejerrey Odontesthes bonariensis a baja densidad (250 ind/ha); en la primavera del 2001 se repitió el muestreo para evaluar resultados. El trabajo tiene como objetivo comparar ambos momentos e inferir el rol del pejerrey en las modificaciones observadas en el sistema. En 1997 la costa poseía un cinturón de macrófitas sumergidas; las emergentes se distribuían en parches en toda la superficie. La transparencia del agua resultó elevada. El macrozooplancton fue escaso, con presencia de calanoideos. No se capturó pejerrey y las otras especies de peces resultaron poco numerosas. En 2001 no se observaron macrófitas sumergidas. La transparencia del agua disminuyó a la mitad. El macrozooplancton fue abundante; se capturaron dos clases de edad (2000 y 1999) de dientudo Oligosarcus jenynsi y sabalito Cyphocharax voga, especies ausentes en el muestreo previo. Las diferentes variables biológicas del pejerrey manifiestan una excelente colonización. Se establecieron las dietas de los peces para dilucidar las principales interacciones tróficas presentes. La predación del macrozooplancton por parte del pejerrey, pudo beneficiar el fitoplancton en detrimento de las macrófitas sumergidas y contribuir al pasaje de la laguna de aguas «claras» a «turbias». El elevado número de zooplanctontes puede estar influenciado por el momento de muestreo. La presencia de un ambiente despoblado potenció el restablecimiento del pejerrey. El reciente y exitoso ingreso de O. jenynsi y C. voga se facilitó por la diferente oferta ambiental. El dientudo cumple el rol de superpredador, ocupando la cima de la nueva red trófica. La adaptación del sabalito, de régimen algófago, estaría vinculada al mayor desarrollo logrado por su comunidad presa. La presencia del pejerrey habría actuado como disparador de los cambios ecosistémicos evidenciados, produciendo un efecto cascada sobre otros componentes.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

Diagnóstico ictiológico de la laguna La Peregrina, partido de Gral. Pueyrredón, para su incorporación al circuito productivo

During the last decades lagunas were massively incorporated to the circuit of sport fishing, as a reaction to quality and quantity increase of the demand for this activity’s practice. «Domino effect» was the main responsible for opening of this fishermen helped by attracting economic yields. Laguna La Peregrina is a typical case. From the human point of view, the pejerrey Odontesthes bonarienses has not been taken advantage of as there have been very few extractions. To use the environment with profitable purposes, a diagnosis of fishing resources was made in order to schedule a plan for taking advantage thereof. Samplings were made in autumn 2003. Information from the physicchemical and biological aspects was obtained with emphasis on ichthyocenosis. Density was low related to scarce density of phytoplankton, dominated by cyanophytas. Zooplankton was abundant. Fish diversity was low with pejerrey predominance, whose catch per unit effort (cpue) was very high, and specimen had excellent bearing and condition. Specimens greater than 300 mm Lstd were zooplanktophagous, the rest of the status were from other communities.It was highlighted size distribution, gonadal activity, alevins capture, decompensate relation of sexes, greater length average of females and disorder in scales. The raised hypotheses allude to a sampling error, different growth for each sex, thermo dependence sexual regulation, and presence of a estrogenic substances in the aquatic environment. Processed diagnosis showed that plankton chain constitutes the base of the main trophodynamics relations of the system. Phytoplankton was intensely grassing by zooplankton, which, in trophic terms, maintains ichthyocenosis dominated by the pejerrey, whose demographic parameters and condition are totally favorable to establish a sport fisheries. Previously, water quality analysis must be performed to explain potential presence of polluting agents of agricultural origin.During the last decades lagunas were massively incorporated to the circuit of sport fishing, as a reaction to quality and quantity increase of the demand for this activity’s practice. «Domino effect» was the main responsible for opening of this fishermen helped by attracting economic yields. Laguna La Peregrina is a typical case. From the human point of view, the pejerrey Odontesthes bonarienses has not been taken advantage of as there have been very few extractions. To use the environment with profitable purposes, a diagnosis of fishing resources was made in order to schedule a plan for taking advantage thereof. Samplings were made in autumn 2003. Information from the physicchemical and biological aspects was obtained with emphasis on ichthyocenosis. Density was low related to scarce density of phytoplankton, dominated by cyanophytas. Zooplankton was abundant. Fish diversity was low with pejerrey predominance, whose catch per unit effort (cpue) was very high, and specimen had excellent bearing and condition. Specimens greater than 300 mm Lstd were zooplanktophagous, the rest of the status were from other communities. It was highlighted size distribution, gonadal activity, alevins capture, decompensate relation of sexes, greater length average of females and disorder in scales. The raised hypotheses allude to a sampling error, different growth for each sex, thermo dependence sexual regulation, and presence of a estrogenic substances in the aquatic environment. Processed diagnosis showed that plankton chain constitutes the base of the main trophodynamics relations of the system. Phytoplankton was intensely grassing by zooplankton, which, in trophic terms, maintains ichthyocenosis dominated by the pejerrey, whose demographic parameters and condition are totally favorable to establish a sport fisheries. Previously, water quality analysis must be performed to explain potential presence of polluting agents of agricultural origin

Estudio limnológico de Laguna Blanca Chica (Olavarría, provincia de Buenos Aires) durante un período de sequía

The aquatic ecosystems of the Pampean plains usually have highly variable dynamics which affects the abundance of fish resources. We analyzed Blanca Chica shallow lake located in the central region of the province of Buenos Aires. It has neither tributaries nor effluents. It hosts sport fishing, water sports without engine, and its surroundings are used for recreation. Here we report the effects of drought in the structure and functioning of the shallow lake, with emphasis on the fish community. Limnological and ichthyologic analyses were carried out in 2007, 2008, 2011 (year characterized by extreme regional dry period) and 2014. In 2007 the phytoplankton was dominated by Botryococcus braunii. Pejerrey (Odontesthes bonariensis) was dominant in the fish samples, but showing an important decrease in numbers and biomass. Catch per unit effort (CPUE) was low and showed poor fish quality with high taeniasis. In 2008, zooplankton improved both in quality and quantity and became the basis of pejerrey`s diet, which effectively increased its abundance and its biomass, with fish in the 1- and 2-year class. In 2011 the conductivity, chlorophyll-a, chlorides, sodium, ammonium and sulfates were one order of magnitude above historical values. The extreme limnological conditions and notorious area reduction triggered a total absence of fish. The 2014 campaign showed that the shallow lake level had increased from 1,5 to 2 m. However, no fish were detected; the absence may be explained by the lake’s isolation and natural massive mortality occurred.Facultad de Ciencias Naturales y Muse

¿El pejerrey puede causar cambios estructurales en un ecosistema?

La laguna Del Estado se secó circunstancialmente a comienzos de la década de 1960. El aislamiento hidrológico superficial del ambiente impidió la recolonización masiva de peces. En octubre de 1997 se realizó un diagnóstico de situación a partir del cual se sembraron alevinos de pejerrey Odontesthes bonariensis a baja densidad (250 ind/ha); en la primavera del 2001 se repitió el muestreo para evaluar resultados. El trabajo tiene como objetivo comparar ambos momentos e inferir el rol del pejerrey en las modificaciones observadas en el sistema. En 1997 la costa poseía un cinturón de macrófitas sumergidas; las emergentes se distribuían en parches en toda la superficie. La transparencia del agua resultó elevada. El macrozooplancton fue escaso, con presencia de calanoideos. No se capturó pejerrey y las otras especies de peces resultaron poco numerosas. En 2001 no se observaron macrófitas sumergidas. La transparencia del agua disminuyó a la mitad. El macrozooplancton fue abundante; se capturaron dos clases de edad (2000 y 1999) de dientudo Oligosarcus jenynsi y sabalito Cyphocharax voga, especies ausentes en el muestreo previo. Las diferentes variables biológicas del pejerrey manifiestan una excelente colonización. Se establecieron las dietas de los peces para dilucidar las principales interacciones tróficas presentes. La predación del macrozooplancton por parte del pejerrey, pudo beneficiar el fitoplancton en detrimento de las macrófitas sumergidas y contribuir al pasaje de la laguna de aguas «claras» a «turbias». El elevado número de zooplanctontes puede estar influenciado por el momento de muestreo. La presencia de un ambiente despoblado potenció el restablecimiento del pejerrey. El reciente y exitoso ingreso de O. jenynsi y C. voga se facilitó por la diferente oferta ambiental. El dientudo cumple el rol de superpredador, ocupando la cima de la nueva red trófica. La adaptación del sabalito, de régimen algófago, estaría vinculada al mayor desarrollo logrado por su comunidad presa. La presencia del pejerrey habría actuado como disparador de los cambios ecosistémicos evidenciados, produciendo un efecto cascada sobre otros componentes.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

Diagnóstico limnológico pesquero de 6 lagunas del partido de Puán

The territory of Puán County encompasses 133 shallow lakes, which resources are barely used. Technical knowledge of the shallow lakes is limited, hence the management policy currently being applied is generic. The aim of this paper is to make a primary proposal for the strategic use of the fisheries, supported by an expeditious diagnostic of various environments. Each shallow lake exhibits particular characteristics. The CPUE ranges from 0 to very abundant. In general, the rate of exploitation is low, producing an excellent yield and high quality fish resources. The trophic chain is short, with relevant zooplankton size and density, sustaining an abundant pejerrey Odontesthes bonariensis population. The services offered to the anglers in the shores are few or nonexistent. Tourism development is scarce in spite of the strong potential. Weaknesses and strengths are analyzed considering different parameters and situations. The use of resources through sport fishing is proposed, targeting on high-income fishermen looking for high quality pejerrey catch in a near pristine shallow lake and enjoying privacy. Such a fisherman demands quality and professionalism in the services received, as well as personal or exclusive attention by providers. On the other hand, those shallow lakes not selected for a sport fishing circuit, can be managed by the local government allowing the catch of pejerrey, controlling the correct use of gill nets, creating more jobs, and also providing fish to the town’s popular kitchens feeding the needy. The potential emergent problems contemplated in the execution of the project are listed and compared to the current situation.The territory of Puán County encompasses 133 shallow lakes, which resources are barely used. Technical knowledge of the shallow lakes is limited, hence the management policy currently being applied is generic. The aim of this paper is to make a primary proposal for the strategic use of the fisheries, supported by an expeditious diagnostic of various environments. Each shallow lake exhibits particular characteristics. The CPUE ranges from 0 to very abundant. In general, the rate of exploitation is low, producing an excellent yield and high quality fish resources. The trophic chain is short, with relevant zooplankton size and density, sustaining an abundant pejerrey Odontesthes bonariensis population. The services offered to the anglers in the shores are few or nonexistent. Tourism development is scarce in spite of the strong potential. Weaknesses and strengths are analyzed considering different parameters and situations. The use of resources through sport fishing is proposed, targeting on high-income fishermen looking for high quality pejerrey catch in a near pristine shallow lake and enjoying privacy. Such a fisherman demands quality and professionalism in the services received, as well as personal or exclusive attention by providers. On the other hand, those shallow lakes not selected for a sport fishing circuit, can be managed by the local government allowing the catch of pejerrey, controlling the correct use of gill nets, creating more jobs, and also providing fish to the town’s popular kitchens feeding the needy. The potential emergent problems contemplated in the execution of the project are listed and compared to the current situation

Diagnóstico ictiológico de la laguna La Peregrina, partido de Gral. Pueyrredón, para su incorporación al circuito productivo

During the last decades lagunas were massively incorporated to the circuit of sport fishing, as a reaction to quality and quantity increase of the demand for this activity’s practice. «Domino effect» was the main responsible for opening of this fishermen helped by attracting economic yields. Laguna La Peregrina is a typical case. From the human point of view, the pejerrey Odontesthes bonarienses has not been taken advantage of as there have been very few extractions. To use the environment with profitable purposes, a diagnosis of fishing resources was made in order to schedule a plan for taking advantage thereof. Samplings were made in autumn 2003. Information from the physicchemical and biological aspects was obtained with emphasis on ichthyocenosis. Density was low related to scarce density of phytoplankton, dominated by cyanophytas. Zooplankton was abundant. Fish diversity was low with pejerrey predominance, whose catch per unit effort (cpue) was very high, and specimen had excellent bearing and condition. Specimens greater than 300 mm Lstd were zooplanktophagous, the rest of the status were from other communities.It was highlighted size distribution, gonadal activity, alevins capture, decompensate relation of sexes, greater length average of females and disorder in scales. The raised hypotheses allude to a sampling error, different growth for each sex, thermo dependence sexual regulation, and presence of a estrogenic substances in the aquatic environment. Processed diagnosis showed that plankton chain constitutes the base of the main trophodynamics relations of the system. Phytoplankton was intensely grassing by zooplankton, which, in trophic terms, maintains ichthyocenosis dominated by the pejerrey, whose demographic parameters and condition are totally favorable to establish a sport fisheries. Previously, water quality analysis must be performed to explain potential presence of polluting agents of agricultural origin.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

Diagnóstico limnológico pesquero de 6 lagunas del partido de Puán : Propuesta de pautas de gestión del recurso

The territory of Puán County encompasses 133 shallow lakes, which resources are barely used. Technical knowledge of the shallow lakes is limited, hence the management policy currently being applied is generic. The aim of this paper is to make a primary proposal for the strategic use of the fisheries, supported by an expeditious diagnostic of various environments. Each shallow lake exhibits particular characteristics. The CPUE ranges from 0 to very abundant. In general, the rate of exploitation is low, producing an excellent yield and high quality fish resources. The trophic chain is short, with relevant zooplankton size and density, sustaining an abundant pejerrey Odontesthes bonariensis population. The services offered to the anglers in the shores are few or nonexistent. Tourism development is scarce in spite of the strong potential. Weaknesses and strengths are analyzed considering different parameters and situations. The use of resources through sport fishing is proposed, targeting on high-income fishermen looking for high quality pejerrey catch in a near pristine shallow lake and enjoying privacy. Such a fisherman demands quality and professionalism in the services received, as well as personal or exclusive attention by providers. On the other hand, those shallow lakes not selected for a sport fishing circuit, can be managed by the local government allowing the catch of pejerrey, controlling the correct use of gill nets, creating more jobs, and also providing fish to the town’s popular kitchens feeding the needy. The potential emergent problems contemplated in the execution of the project are listed and compared to the current situation.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

Diagnóstico limnológico pesquero de 6 lagunas del partido de Puán : Propuesta de pautas de gestión del recurso

The territory of Puán County encompasses 133 shallow lakes, which resources are barely used. Technical knowledge of the shallow lakes is limited, hence the management policy currently being applied is generic. The aim of this paper is to make a primary proposal for the strategic use of the fisheries, supported by an expeditious diagnostic of various environments. Each shallow lake exhibits particular characteristics. The CPUE ranges from 0 to very abundant. In general, the rate of exploitation is low, producing an excellent yield and high quality fish resources. The trophic chain is short, with relevant zooplankton size and density, sustaining an abundant pejerrey Odontesthes bonariensis population. The services offered to the anglers in the shores are few or nonexistent. Tourism development is scarce in spite of the strong potential. Weaknesses and strengths are analyzed considering different parameters and situations. The use of resources through sport fishing is proposed, targeting on high-income fishermen looking for high quality pejerrey catch in a near pristine shallow lake and enjoying privacy. Such a fisherman demands quality and professionalism in the services received, as well as personal or exclusive attention by providers. On the other hand, those shallow lakes not selected for a sport fishing circuit, can be managed by the local government allowing the catch of pejerrey, controlling the correct use of gill nets, creating more jobs, and also providing fish to the town’s popular kitchens feeding the needy. The potential emergent problems contemplated in the execution of the project are listed and compared to the current situation.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA