Número 24

Biología Acuática | Número 24: IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (EMEAP). Trabajos completos

2020-06-11T20:04:15Z

Edicion de revista Biología Acuática; no. 24 Edición que contiene todos los trabajos presentados en el IV EMEAP (La Plata, 2008).

Metabolismo de productores de un arroyo pampeano

2021-03-24T19:21:06Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 Low current velocities, high nutrient levels, the lack of riparian forest vegetation, and the development of dense and rich macrophyte communities characterize many Pampean streams. The objective of this study was to describe the most important sources of production and respiration in different communities of a pampean stream, and to compare the energetic support of the trophic web in streams of other places. Production and respiration estimations were carried out using clear and opaque acrylic chambers in the same reach of the stream, in two opportunities in summer and one opportunity in winter. The results indicated that the macrophyte community is the most important one in capturing and transforming light energy, although the epiphyton and phytobenthos communities support many herbivorous and are the bottom of the trophic web at this stream. Therefore, the gross production is higher than many others are streams but no the food offer to grazers.

Algas epífitas indicadoras de calidad del agua en arroyos vinculados a la Laguna de los Padres

2019-12-17T18:39:36Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 Diatoms constitute a useful tool to evaluate the trophic status of aquatic systems, as they answer quickly to environmental changes. They have been used in water quality researches since the beginning of the 20th century, but only few reports are available from Argentina. In the present paper, several biological descriptors have been employed to evaluate the water quality of the influent and effluent streams from Los Padres Lagoon (Los Padres and La Tapera creeks, respectively), including Descy Index (DI) and Pampean Diatoms Index (PDI). In each creek, ten stems of the «giant bulrush» (Schoenoplectus californicus) were randomly collected and the main physical and chemical parameters were recorded in situ. In the laboratory, periphyton was removed and algae taxa were identified and counted. A total of 107 periphytic taxa were identified (83 at the inflow and 101 at the outflow). Diatoms constituted the richest and the most abundant group in both creeks. DI and PDI indices showed a higher eutrophic level in the influent, possibly due to the input of an important quantity of agricultural polluents of the surrounding lands and to the strong impact of birds. Species composition, diversity and equitability were the only biological descriptors suitable to assess the water quality in the present study.

Micobiota parásita de ambientes acuáticos de la provincia de Buenos Aires

2019-04-05T12:16:22Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 Zoosporic fungi (Chytridiomycota, Hyphochytridiomycota and Peronosporomycota) include organisms that occur as saprotrophs on vegetable debris or as parasites of invertebrates, plants, algae and of other zoosporic fungi. Water samples and floating organic matter were collected during a 2005-2006 survey at Las Cañas stream and Villa Elisa channel (Reserva Natural Selva Marginal Punta Lara, Pdo. de Ensenada, Bs. As.), and samples were processed with the baiting technique. Six taxa of parasitic zoosporic fungi were recovered: Olpidium sp. (Braun) Rabenhorst, Chytridium sp. Braun and Rhizophydium carpophyllum (Chytridiomycota), Rhizidiomyces apophysatus and R. hirsutus (Hyphochytridiomycota), Olpidiopsis pythii (Butler) Karling and Dictyuchus sp. Leitgeb, (Peronosporomycota). Olpidiopsis pythii is the first record for Argentina and South America.

Análisis de las interacciones tróficas en microcosmos: estudio preliminar

2020-09-11T17:03:44Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 The aim of the study was to analyze the effect of planktivorous fish on the trophic interactions between a palatable algae and a filter feeding (Daphnia spinulata). A lab experiment was performed using microcosms of 2 l. Three treatments were carried out: with fishes (P), with cladocerans (C), with fishes and cladocerans (CP) and a control (A). They were inoculated with 200 ml of Scenedesmus acutus. The experiment lasted 5 days and samples were taken every 8 hours. Microcosms were kept at a 16:8 hours of light:dark cycle with constant temperature and with a non limiting level of nutrients (P and N) for algal development. pH values were constant. Turbidity was used as an indirect means of algal biomass ( r = 0.95; p < 0.05). The clearing effect of D. spinulata was more marked at the end of the experiment, with turbidity dropping down in the treatment without fish (C), and showing significant differences when compared with treatments (P) and (A). Differences in turbidity between (P) and (A) showed a possible recycling of nutrients by the fish. Algal palatability was also evident, because cladoceran populations were tripled in density. In (CP), predation by fish was observed resulting in the absence of Daphnia spinulata at the end of the experiment. In experiments with algal mono specific culture, turbidity could be used as an indirect means of algal biomass because, since its register is immediate, it can be measured repeatedly causing minimal disturbance.

Humedales construidos: una alternativa para el manejo de la polución

2019-04-05T12:16:13Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 Municipal wastewaters and urban and agricultural runoffs are important factors of natural waters pollution in Buenos Aires province. The use of constructed wetlands for wastewaters treatment is now a proven and accepted low cost technology, able to improve the quality of great volumes of water. They are used in a wide range of sizes, until 15.000 ha treating 75.000 m3.d-1. The analysis of 159 case studies, ranging from 0.2 to 500 Ha used for wastewater treatment or maturation, conclude that loads of 0.7 – 5 cm. d-1; areas of 2 – 14 ha.1000m-3.d-1 or 5 – 35 m2. pe-1, can improve water quality to almost that of the natural waters of the region. The range width refers to the previous treatment. The use of these recommended loads do not affect wetland’s community structure but improve its capacity to hold wild life and biodiversity. In Buenos Aires province there are many examples of polluted water bodies close to natural wetlands potentially useful to avoid those damages. A few cases are analizad.

Dinámica de formas inorgánicas de nitrógeno en suelos inundados de la cuenca del Río Salado: experiencia «in situ»

2019-12-17T18:41:58Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 In lowland river basins with agricultural activities and periodically flood events, the exchange of materials and organisms between waterlogged soil and river are significant. One century conversion of natural systems to agriculture in the Argentine Pampas has resulted in significant changes of ecological properties of the valuable freshwater ecosystems of its region. For this reason it becomes essential to know soil basin responses to flood events and its reciprocal effects on the river. The aim of this paper was to determine the nitrate (NO3 -) and ammonium (NH4 +) dynamics on soil flooded waters with different land-use and topographic position, since the flood to the dry condition. «In situ» experiences were carried out on soils from Salado River basin (Valdés, 25 de Mayo). The treatments (4x3) were made according to: land-use (agricultural ‘a’ and cattle-agricultural ‘m’) and topographic position (ridge ‘L’ and middle ridge ‘ML’). NO3 - and NH4 +, chlorophyll ‘a’ and dissolved oxygen were measured in water. According to water time permanence on each site (calculated taking into account the slope in each site) five sample times were programmed: daily in L and fortnightly in ML. In all cases NO3 - values were higher than NH4 +. Water NO3 - and NH4 + concentrations were similar in ‘a’ and ‘m’ in both topographies. According to the topography and time of water permanence, NO3 - mean values were higher for L (five days), while the opposite occurred for NH4 +. Both ions dynamics showed differences according to topography and water time permanence, but not according to land-use. These results suggested that in flooded events of lowland river basins with farming land use, the nitrogen dynamic and its transport from the soil to the flooding water have significant importance and have a direct influence on phytoplankton biomass development. The NO3 - and NH4 + dynamics were different according to water time permanence over the soil: when the flood event was for long time, the system seem to have enough time to adapt to the new conditions, and so denitrification and nitrification processes are possible; but, when the flood event is short, time is not enough for the system to adapt, and thus, nitrification and denitrification processes does not seem to occur. Considering that some authors assumed soil basin agriculture as the former responsible for the increasing nutrient concentration in the river, these results suggest that because crop-pasture, cattle lands are important in this respect and should be considered from now on.

Nutrientes y clorofila-a durante el período de inundación 2001-2002 en la Laguna Chascomús (Argentina)

2019-04-05T12:16:02Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (EMEAP) (La Plata, 2008); Biología Acuática; no. 24 Total phosphorus, total nitrogen and chlorophyll-a concentrations were determined weekly in a pelagic zone in Chascomús Pond between April 2001 and September 2002. Two flood periods took part with 8 metres over sea level (IGM) during this time (June- January 2002 and April-June 2002), where in both of them two maximum peaks with about 9 meters were registered. As a consequence a diminution of the salinity to one third of the mean value of 1,57 g.l-1 was observed, because of the dilution promoted by rainwater which was higher in a 40% of the mean 600 mm of the latest five years. Nevertheless, this fact had not occurred with total phosphorus, mean 0,48 mg.l-1, referring to 0,48 mg.l-1 obtained in 1999-2000, while total nitrogen, mean 1,45 mg N.l-1, was nearly in the same order in relation to a previous value of 1,56 mg N.l-1 (1983-1984) and chlorophyll-a, mean 198,2 μg.l-1, showed a significant increment taking into account the concentration of 89,1 μg.l-1 determined during 1999-2002. These results indicate that because of flood events a supply of nutrients reaches the pond coming from wastes of the city (30000 inhabitants), as well as from the effluent of the treatment plant. Normally, the latter go to Girado stream and finally are received by Adela Pond in direction to Salado River, but the inversion of the flux makes these wastes reach Chascomús Pond during flood periods.

Producción intensiva de juveniles de pejerrey (Odontesthes bonariensis)

2019-04-05T12:15:51Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 The objective of this work is to produce Odontesthes bonariensis juveniles in an intensive system. The experience lasted 196 days and during this, survival, growth, and production were studied. The first 16 days 29.000 hatched larvae were kept outdoors in two circular tanks of 2.000 liters each. They were fed with zooplankton, Artemia and artificial food. The total number of individuals obtained was 23.000, these were transferred to 100 m2 pond previously fertilized where they were reared during 180 days. The initial density was of 230 ind/m2 with a total average length of 15,03mm (±0,60 standard deviation) and average weight of 0,024 g.(±0,0041 standard deviation). The juveniles were fed 4 times a day with artificial food. Samples were taken in order to calculate length and weight growth, at the end of experiment survival and production were calculated. The final number of juveniles obtained was 16.503 with a final average length of 110,28mm. (±17,88 standard deviation) and average weight of 11,28g(±6,07standard deviation). The food conversion rate was 1,31. Survival rate was 71,75 %. The final production was 19.418,3 Kilogram/hectare after 180 days of rearing. These results show that massive production of juveniles is possible. The high density used, the final weight reached and the high percentages of survival allowed the biggest pejerrey juvenile production in Argentina after 196 days of rearing.

Nuevos datos sobre Hypostomus commersoni (Siluriformes: loricariidae) anómalo en la Laguna Chascomús (Buenos Aires, Argentina)

2019-04-05T12:15:48Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 An anomalous specimen of Hypostomus commersoni was captured in «laguna» Chascomús, in August, 2005. This specimen presents a shortening of the craneal region with reduction of the dorsal – lateral plates of the head, reflecting a marked loss of the symmetry. The rest of the body does not show evident modifications.

Lerneosis en peces silvestres y cultivados del centro de Argentina

2021-03-24T19:13:10Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (EMEAP) (La Plata, 2008); Biología Acuática; no. 24 The genus Lernaea (Crustacea) comprises ectoparasitic copepods with worldwide distribution. Lernaea causes damage in the skin of fishes and facilitate secondary infections. In the present work, several outbreaks of lernaeosis in the central region of Argentina, the ichthyofauna involved and their main epidemiological features were assessed. In 41 cases from 1993 to 2006, 14 species from five provinces were affected. The fishes were either cultured or wild and ornamental or edible. The parasite was determined as Lernaea cyprinacea L. 1758. The intensity of infection was correlated with water temperature (rs= 0.71, P< 0.05). The prevalence was variable with maximum between 80.9 to 100% in Oligosarcus jenynsii and Cyprinus carpio, respectively. Odontesthes bonariensis, one of the most important continental fishing species in Argentina, was the most affected in the wild group (53.6% of the total outbreaks). However, the intensity of infection was low to median (≤ 7 parasites per host) in this species. In three situations analized, there were no significat differences in body condition of O. bonariensis between parasited and non-parasited (P> 0.05). Among the ornamental species, Carassius auratus had the most prevalence. In several outbreaks, L. cyprinacea was a part of a multiaetiological complex causing fish mortalities.

Aspectos ecológicos de las lagunas pampeanas y su posible influencia sobre las pesquerías del pejerrey: el caso de laguna El Coraje

2019-04-05T20:05:12Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 El Coraje shallow lake is an arheic and semi permanent environment, located in SE of the Province of Buenos Aires, mainly dedicated to sport fishing. Precipitation cycles, alternating above and bellow the average, cause frequent changes in its area, currently highly reduced. The aim of this paper is to characterize the fish community of El Coraje shallow lake, and to determine the possible causes and consequences of the massive mortality inferred. A limnological and ichtiological sampling was made during April 2006, when the drought was extreme. Chemical analyses evidence ion concentration, including nutrients (total phosphorous = 1,454 ppm). Turbidity was high (Secchi disk = 14 - 18 cm) as well as chlorophyll- a (318 mg/m3). A bloom of Nodularia was observed, responsible for a scent similar to gamexane. Macrozooplanckton was abundant. The operations with trawl net became difficult due to the excess of accumulated sediment. Using the gill net, only pejerrey (Odontesthes bonariensis) could be found, and in a bad sanitary state. However, the k factor and relative weight didn’t show any link to recent affectations (except for a higher length). Specimens presented haemorrhages in eyes and body. All of them had their eyes affected of diverse way and degree, in some cases with total absence of the ocular globe. Metacercaries of Trematode in high numerosity were observed in brain. Fins presented different morphologic alterations, with loss of ratios, adjudged to bacterial diseases. A prevalence of Cestode and Nematode in high density was observed in the digestive tube. Moreover, in average 76 % of the tube was empty. Hence, there are many environmental variables (bacteria, ion concentration, phytoplankton blooms, etc.) that add up to affect the fish community and generate stress, causing fish mortality.

Dinámica de la biomasa poblacional para evaluar el uso de los indicadores de la perfomance de crecimiento en el pejerrey Odontesthes bonariensis

2019-04-05T20:05:07Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 The description of fish population demographic can be carried out with the estimate of key parameters: asymptotic length and weight (L∞ and W∞ ), growth constant (K), initial number of each cohort at times zero (N0) and mortality coefficient (Z). If the base information was obtained from samples taken with fishing gears with similar efficiencies, it would be possible to evaluate the population’s historical changes or to carry out comparisons among populations of different water body. Both situations are difficult to approach. Performance indices more used were presented like a simple tool of growth parameters integration with the purpose of facilitating the comparison. In this paper, the parameter T (maximum biomass time or age) and its standardization for the silverside is presented. This index may be used as tool to evaluate how far or close a population is regarding the standard values of growth and survival. So, it can be combining with performance indices in order to accepting the differences when T is next to the standard values for this species and to reject them when it moves away from T standard values.

¿Existen migraciones verticales en el zooplancton de la Laguna de Los Padres?

2019-04-05T20:05:04Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 Diel vertical migration is a widely studied phenomenon occurring specially in marine and well stratified continental systems. The aim of this work was to study the spatial distribution of zooplankters in a «pampasic» shallow lake and to look for the existence of vertical migration. During summer 2002, replicated samples were taken during two 24 hintervals in the pelagic zone, using the 12 L Schindler-Patalas trap. Twenty-nine taxa were registered, corresponding 23 to Rotifera, 4 to Cladocera and 2 to Copepoda. The three groups considered in this work were generally located deeper when the water transparency was the highest. Maximum and minimum depths of residence were registered during light and dark hours, respectively. This probably indicates that changes in light could induce zooplankton movements. Although the vertical pattern observed in zooplankton populations from Los Padres Lake was similar to that of stratified lakes, with an ascending movement of individuals at dusk and a descending movement at dawn, it was not as pronounced as in deeper lakes. In order to obtain an explanation of the observed pattern, future work should deal with the description of spatial and temporal changes in abundance and availability of the resources.

Fitoplancton de una laguna pampásica (San Miguel del Monte, Buenos Aires, Argentina): variación espacio-temporal de los grupos funcionales

2020-09-11T16:56:35Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 Phytoplankton assemblages were analyzed taking into account the functional groups in a shallow lake connected to the lower basin of Salado River. Samples were obtained monthly (9/1997-8/1998), from the affluent (E1), San Miguel del Monte lake (E2) and the connection with Las Perdices lake (E3). Species with biovolume higher than 0.5 mm 3 .l-1 and contributing to 5-73 % of total biovolume were selected. Moderate eutrophy favored the development of filamentous cyanobacteria (S1 and S2 functional groups), unicellular flagellates (Y and X2) and nitrogen fixed cyanobacteria (H and H1). Colonial cyanobacteria (X1 and K) coexisted with filamentous cyanobacteria in coincidence with high phosphorus values. Biovolume of unicellular flagellates increased in relation to the input of nutrients from Salado River. At E3, filamentous cyanobacteria (S1, S2, H1 and H) were dominant and species of Y and X1 groups were co-dominant. At E1, colonial cyanobacteria (M), typical from eutrophic lakes with high organic matter, were found in high densities. Phytoplankton functional classification introduced by Reynolds gives an invaluable information and represents a good complement to understand the ecological characteristics of the algae and the phytoplankton dynamics in San Miguel del Monte Lake».

Contenido clorofílico del epifiton sobre Scirpus californicus en la laguna La Rosita (partido de Castelli)

2019-04-05T20:04:50Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 La Rosita shallow lake is located in the south of Castelli city. With a surface area of 162 ha, 80% of the lake is covered by stands of californian bulrush. With the aim of studying dynamics of periphyton growth on this substrate, epiphytic chlorophyll content was analyzed in stands of Scirpus californicus located in shallow and deep zones, presenting differential development of floating and submerged macrophytes. Replicated samples of epiphyton were obtained monthly, during an annual period, by scrapping the total submerged area of bulrush axes in three sites of the shallow lake. Axe density was quantified in random fields and floating and submerged macrophyte cover percentages were estimated. Pigment extraction was performed according to Lorenzen (1967) and calculation of chlorophyll a concentration was carried out following Varela (1981). At the same time, water physic and chemical variables were measured. Evident spatial and temporal differences were found regarding epiphyton dynamics at the sampling points. At shallow sites (average depth 0,67 m), the maximum value of chlorophyll a concentration was 6,5 mg/m2, while at deep points (average depth 1,02 m) this variable only attained a maxima of 0,38 mg/m2. The factors that may have affected the chlorophyll content of periphyton were water column depth, submerged macrophyte cover (mainly Ceratophyllum demersum) and the age and growth period of californian bulrush. Floating macrophyte cover (principally Ricciocarpus sp.) may have affected too, no sufficient evidence could be gathered.

Variación estacional del fitoplancton en la cuenca inferior del Río Salado (provincia de Buenos Aires)

2019-12-17T18:48:01Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 The main aim of this survey was to analyze seasonal variations in phytoplankton composition, relating its behaviour to temperature and conductivity, at El Destino (ED) sampling site in the Salado river lower-basin. A total of 28 phytoplankton samples were taken twice a week from 9/3 to 20/7/2004 and were analysed according to Utermöhl method. In total, 145 algae taxa were identified, although rare species were discarded in order to avoid statistical misinterpretation. Correlation coefficients and autocorrelation analyses (Q-Ljung-Box statistic) were performed in order to establish seasonal patterns of species abundance. Significant autocorrelations (p <0.05) were observed between phytoplankton species and temperature-conductivity patterns, thus illustrating their seasonal behaviour. Moreover, taxa were grouped according to their occurrence during different water temperature periods: (1) a ‘summer’ group, included 41 species that were well represented during warm-waters (>22ºC) like Planctonema lauterbornii, Chondrocystis dermochroa, Geminella interrupta, Chrooccocus spp., Merismopedia spp., among others; (2) a ‘winter’ group, which included 10 species whose highest densities were reached during the cold-waters period (<12ºC) for e.g. Binuclearia sp, Nitzschia fruticosa, Schroederia indica, Microcystis firma; (3) a ‘transitional’ group, of only 4 species with abundance peaks during ‘intermediate’ conditions (15.5ºC average) with Closteriopsis acicularis and Nodularia spumigena being the most remarkable; and (4) an ‘indifferent’ group, with 29 species of random behaviour whose autocorrelations remain within confidence limits, like Thorakochloris nygaardii, Pseudoanabaena limnetica, Monoraphidium giffithii, Scenedesmus linearis, etc. An evident seasonal succession was detected, having species substitution from summer warm-stagnant adapted species to cold-waters favoured ones, hence indicating different successional stages.

Efectos de un hidrocarburo aromático policíclico (ß naftoflavona) sobre biomarcadores de efecto en Corydoras paleatus en condiciones de campo y laboratorio

2019-04-05T20:04:43Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 Polycyclic aromatic hydrocarbons (PAHs) are important anthropogenic sources of aquatic contamination. In this study, hepatic biomarker responses of Corydoras paleatus injected with one sublethal dose of a PAH (ß-naftoflavona, BNF) were assessed under laboratory and field conditions. Glutathion-S-transferase (GST) and catalase (CAT) hepatic activities, liver protein content (PC), condition factor (CF) and liver somatic index (LSI) were determined. Two bioassays were performed during winter time: laboratory (la) and field (ca). Fish were injected with 50 mg BNF/kg body weight dissolved in corn oil (ß-la y ßca); control fish received corn oil (C-la y C-ca). There were no differences between controls or in BNF injected fish in the assessed parameters. BNF provoked a tendency of increase in CAT and GST activities and lower values of CP; on the other hand, no differences were observed in the FC and IHS. In BNF field exposed fish (ß-ca) CAT activity was significantly stimulated vs. both field and laboratory controls; GST differences were detected both between ß-ca and ß-la and their respective controls. BNF exposure induced adverse effects principally in the enzymatic biomarkers of C. paleatus and those effects were modulated by the environmental conditions.

Evaluación preliminar del riesgo sanitario por agroquímicos en aguas del arroyo Azul, provincia de Buenos Aires

2021-03-24T18:24:26Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 Health risk analyses (HRA) indicate whether, and to which extent of severity, a given chemical substance may constitute a threat for health, e.g., the accidental ingestion of water during recreational use with direct contact. Objectives of this paper are to estimate the risk from an accidental ingestion of water carrying agrichemicals (á y ä HCH, Aldrine, ã – Chlordane, Glyphosate, and Imazethapyr) while bathing in the Azul River bathing resort by making use of HRA, and to discuss the potential use of such a tool for water resources management. It is based on the USEPA model, and, with the exception of the concentration of the substance in water, all other variables (ingestion rate, weight of individuals, frequency and duration of the exposition) are treated probabilistically and fit a recreational scenario with direct contact. The aggregated risk is estimated with an additive model of the particular risk of each substance. Results show that the risk, non carcinogenetic effects, may be disregarded because its value is always less than 1 (Aldrine is the principal contributor). Regarding the carcinogenetic effects, although the value is slightly greater than the limiting value of 10-5, the conservative approach of this study makes it to be minimized (its principal contributor is á –HCH). The Buenos Aires Province does not count with regulations referred to the quality of natural waters used for bathing. For that reason, the HRA stand out as an option for decision-makers given the absence of alternative management strategies.

Los humedales pampeanos como herramientas para preservar las lagunas

2019-04-05T12:17:03Z

Articulo IV Congreso de Ecología y Manejo de Ecosistemas Acuáticos Pampeanos (La Plata, 2008); Biología Acuática; no. 24 Wetlands are ecosystems with known potential for particulate material retention. Many water bodies develop near shore wetlands or reed belts supported by external natural o artificial incomes from the drainage basin. The influent slows down and the particulate material sediments and is mineralized avoiding a damage to the water body. In a study done in a reed belt of Las Perdices pond, which receives municipal wastewaters from San Miguel del Monte city, it was concluded that in a surface of 2 – 3 Ha, the influent organic matter could be mineralized, the dissolved oxygen recovered and the inorganic nitrogen and soluble phosphorus concentrations reduced, under certain conditions. Knowing the involved process it is possible to design «tailored ecosystems» that can improve water quality and avoid environmental damage.