La biodiversidad acuática en Argentina: problemáticas y desafíos

La República Argentina posee gran variedad de ecosistemas acuáticos continentales y marinos lo que conlleva a una importante riqueza de especies acuáticas. Sin embargo, en las últimas décadas los ecosistemas acuáticos y la biota asociada a los mismos han sido impactados por diversas problemáticas como la contaminación, la sobreexplotación de especies, la presencia de especies invasoras, la alteración en los corredores de desplazamiento de la biota acuática y los cambios asociados a la variabilidad climática, entre otras. Estas problemáticas influyen sobre las interrelaciones tróficas de los ecosistemas, la pérdida de hábitats, los cambios en la calidad del agua y los usos y servicios ecológicos que brindan estos ambientes a las poblaciones locales. En este trabajo se presentan algunos ejemplos de las problemáticas que afectan la biodiversidad acuática en Argentina en las últimas décadas, se analizan los nuevos desafíos que se presentan en esta temática y se proponen líneas de acción tendientes a realizar un manejo sustentable de la biodiversidad acuática.Argentina has a wide variety of continental and marine aquatic ecosystems and a high aquatic biodiversity. However, in recent decades aquatic ecosystems and biota associated with them, have been influenced by several problems such as pollution, overfishing, invasive species, alteration in the ecological corridors of aquatic biota and changes associated with climate variability, among others. These issues influence trophic relationships of ecosystems, habitat loss, changes in water quality and uses of ecological services that provide these environments to the local populations. This paper presents some examples of the problems that affect aquatic biodiversity in Argentina; new challenges on this subject are analyzed and lines of action aiming at sustainable management of aquatic biodiversity are proposed.Fil: Volpedo, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones En Produccion Animal; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; Argentin

Environmental changes on freshwater fish communities in South America in the last five decades: a case study in northeast Argentina.

Environmental changes together with other stressors, such as habitat destruction, may cause widespread extinctions, decrease in biodiversity and disrupt natural communities, resulting in novel species assemblages. South America has a large diversity of freshwater fishes with complex evolutionary histories, mainly due to the presence of a wide variety of aquatic environments. Argentina has experienced an increase in rainfall in the last five decades leading to important climatic and hydrological changes. These changes caused the displacement of the isohyets towards the west. This study reports changes in the composition of freshwater fishes in northeast Argentina during the last five decades, and investigated a causal relationship between the variation in fish assemblages and climate change.The changes in the distribution and composition of fish communities between 1962 and 2010 were analyzed in 22 stations. These stations were agrouped in relation to the ichthyogeographic provinces: Great Rivers province (GRp) and Pampean province (Pp). The correlation between rainfall in relation to the number total species from each of the studied provinces showed a significant positive correlation in Pp and not correlation in GRp. The annual mean river discharge and the number of total species from each ecoregion showed a significant positive correlation in GRp, and not correlation in Pp. The results of this study strongly suggest that the rainfall variations and river discharges observed in northeast Argentina induced changes in the composition of fish assemblages that lead to the redistribution of fish species among ichthyogeographic provinces

Use of otolith strontium:calcium ratio as indicator of seasonal displacements of the silverside (Odontesthes bonariensis) in a freshwater-marine environment

Strontium:calcium ratios were measured in sagittal otoliths of silverside (Odontesthes bonariensis) from a freshwater-marine environment (Paraná River Delta and River de la Plata River, South America) in order to understand its seasonal movements. Conductivity was recorded and the water Sr:Ca ratio was determined by ICP-OES (sites: Paraná River Delta, Concepción del Uruguay, Punta Indio, Samborombón Bay and Punta Rasa, Argentina, and Fray Bentos, Uruguay). A calibration curve of water Sr:Ca ratio vs. otolith Sr:Ca ratio from 4 isolated lentic water bodies was made to predict the water Sr:Ca ratio of the places of silverside displacements in the lower section of the Plata Basin during summer (lotic water bodies). Otolith Sr:Ca ratio of silversides from the Paraná River Delta was associated with the conductivity of water at the locations where the sample was collected (lotic water bodies). The water Sr:Ca ratio increased with increasing conductivity along a latitudinal (north-south) gradient in the lower section of the Plata Basin, with a rapid increment in the outer section of the Río de la Plata River. According to this association and the obtained results in the calibration curve, the silverfish were displacements were in zones where conductivity was 7.45 (mS cm-1), corresponding to the water Sr:Ca ratio in the outer section of the Río de la Plata River (1.92 mmol mol-1). The high values of otolith Sr:Ca ratio found for some fish may indicate that during summer they moved from estuarine waters where salinity increases gradually to the Argentinian Sea.Fil: Avigliano, Esteban. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Produccion Animal; ArgentinaFil: Volpedo, Alejandra. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Produccion Animal; Argentin

Ecomorphological patterns of the sagitta in fish on the continental shelf off Argentine

Morphology and morphometry of the sagittae otolith were studied in fish associated with different substrates. The shape, margins and rostrum of three groups of otoliths from several species were analyzed: group 1 (fish associated with soft substrates, N = 10 species), group 2 (fish associated with hard substrates, N = 10 species) and group 3 (pelagic fish, not associated with the bottom, N = 6 species). E and R indexes were calculated for each species. The value of E = maximum width of the sagitta (WO)/maximum length of the sagitta (LO)%, expresses the relative tendency in the shape otolith (from circular to elongate). The value of R = length of the rostrum (LR)/LO%, expresses the percentage in the total length of the otolith that corresponds to the rostrum. The sagittae of group 1 were circular or polygonal with rounded borders. The rostrum can be absent or poorly developed. The sagittae shape of group 2 was elongated, with ornamented borders and a rostrum. The sagittae of group 3 possessed a prominent rostrum, a deep V-shaped cisure and ornamented borders. Statistical analysis showed no significant differences in the E index of groups 1 and 2, while R values of the three groups were significantly different. These results were compared with 80 other species, belonging to 12 families, from the publisher literature. E and R values could be used to characterize the sagittae of the marine fish and could be considered a useful tool for fish ecology studies.Fil: Volpedo, Alejandra. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Echeverría, Dinorah Diana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Vertebrados; Argentin

¿El otolito de pejerrey (Odontesthes bonariensis), refleja el estrés ambiental?

It has been proven that otoliths reflect morphology, morphometry and chemical composition of the environment that fish frequent. However, it has not been established if extreme environmental changes can be reflected by such structure. In this study, we analyze the morphology and morphometry of otolith sagitta of silverside (Odontesthes bonariensis) living in a setting that shows important environmental changes as Chasicó lake in Buenos Aires province (38°37.380’S- 63°4.735’W). We compared physicochemical parameters of water (pH, conductivity, ion concentration Ca2+, Mg2+ y Cl- ) measured in the lake in 2010 with bibliographic data of 1999, 2003 and 2004 and different morphometric variables of silverside otoliths captured in 1998 and in 2010. The ion concentration of Ca2+, Mg2+ y Cl- increased between 11% and 90% in the period 1999-2010; the lake reduced its surface 20% in conjunction with a decrease in precipitations. We observed alterations in the distinctive morphological otolith pattern in about 18% of the individuals sampled, like irregular edges and perforations. We found a smaller width-length relation of the otolith for the year 2010 thus, indicating a decrease in its circularity. These morphological variations could be provoked by alterations in calcium carbonate deposition related to an increase in salinity and conductivity due to reduction in the surface of the lake. In conclusion, this study would indicate that morphology and morphometry of otoliths reflect environmental stress.Fil: Avigliano, Esteban. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tombari, A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Volpedo, Alejandra. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentin

Silversides (Odontesthes bonariensis) reside within freshwater and estuarine habitats, not marine environments

Otolith core-to-edge Sr:Ca ratio was determined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to analyze the salinity-habitat migration history of the silverside, Odontesthes bonariensis, within the Uruguay River (freshwater) and Río de la Plata Estuary (estuarine water) (Plata Basin, South America). Regular core-to-edge oscillations in Sr:Ca suggest that the silverside makes annual migrations between freshwater (1 PSU) habitats, with no evidence of marine incursion or non-migratory individuals. Empirical equations that represent the relationship between conductivity/salinity and otolith Sr:Ca ratio were used to identify where in an otolith an individual transitioned between freshwater and brackish habitats. In most specimens, the first migration between habitats likely occurred within the first year of life. Average numbers of changes between stable Sr:Ca signatures (sites with different salinities) determined by Change-Point analysis were similar from Uruguay River (8.9 ± 3.7) and Río de la Plata Estuary (7.5 ± 2.5) for comparable age fish (p < 0.05), suggesting that habitat use is similar in both collection sites.Fil: Avigliano, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; ArgentinaFil: Miller, Nathan. University of Texas at Austin; Estados UnidosFil: Volpedo, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; Argentin

Variaciones espacio-temporales e intraespecíficas en la morfología y morfometría de otolitos de Odontesthes bonariensis (Atheriniformes, Atherinopsidae)

The morphological and morphometric features of fish otoliths are species–specific. Moreover, some species are known to show intraspecific variations. These could be due to different environmental conditions, but this possibility has scarcely been explored. For the first time, spatio–temporal and intraspecific variations in the shape and size of the otolith of the South American silverside Odontesthes bonariensis (Valenciennes, 1835) are reported. For commercial purposes, this species was introduced from the Chascomús Shallow Lake (Argentina) into other environments with different characteristics. The otoliths used in this study belong to silversides sampled in 2006 from the Chascomús Shallow Lake (Argentina), and in 2006 from the Titicaca Lake (Bolivia) and the Kasumigaura Lake (Japan). Otoliths collected in 1980 from the Chascomús Shallow Lake were also included in the analysis. The species identity of some specimens was subsequently confirmed by molecular techniques. Results of multivariate analyses indicated that there were significant differences in otolith morphology and morphometry among the silverside populations studied, probably related to the environmental conditions where silversides developed.Las características morfológicas y morfométricas de los otolitos de los peces son especies–específicas. Por otra parte, algunas especies son conocidas por presentar variaciones intraespecíficas. Esto podría ser debido a diferentes condiciones ambientales, pero esta posibilidad ha sido poco explorada. Por primera vez, se reportan variaciones espacio– temporales e intraespecíficas en la forma y el tamaño del otolito del pejerrey Odontesthes bonariensis (Valenciennes, 1835) de América del Sur. Para fines comerciales, esta especie fue introducida desde la laguna de Chascomús (Argentina) en otros ambientes con características diferentes. Los otolitos utilizados en este estudio provienen de pejerreyes muestreados en 1999 en la laguna de Chascomús (Argentina), y en 2006 en el lago Titicaca (Bolivia) y el Lago Kasumigaura (Japón). Otolitos colectados en 1980 en la laguna de Chascomús también se incluyeron en el análisis. La identidad de las especies de algunos ejemplares fue confirmada posteriormente por técnicas moleculares. Los resultados de los análisis multivariados indicaron que existen diferencias estadísticamente significativas en la morfología y la morfometría del otolito entre las poblaciones de pejerrey estudiadas, probablemente relacionada con las condiciones ambientales donde pejerreyes se desarrollaron.Fil: Tombari, Andrea D.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Velez, David. Universidad de Chile; ChileFil: Volpedo, Alejandra. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Histopathological changes in liver and gills of Odontesthes bonariensis inhabiting a lake with high concentrations of arsenic and fluoride (Chasicó Lake, Buenos Aires Province)

Water bodies in the Chaco-Pampean plain contain arsenic (As) and fluoride (F-) occurring naturally. Chasicó Lake, located in the southwest of Buenos Aires Province, has high concentrations of both elements (As, 0.05-0.41 mg/L; F-, 6.74-8.54 mg/L). Fish can be considered as indicators of environmental pollution. The aim of this study was to analyze whether the presence of high concentrations of As and F- found in the liver and gills of Odonthestes bonariensis could be associated to histological changes found in these tissues. Fish were sampled from different locations of the lake. Tissue samples (liver and gills) were subdivided and subjected to an acid digestion to determine As and to an alkaline digestion to determine F-. Morphological changes were assessed using routine histological techniques. As concentrations in the liver were higher than in the gills, while the gills showed higher F- concentrations. The histological examination of the liver and gills showed alterations that could correspond to the effects of the high As and F- concentrations found in these tissues. The toxicity of these elements is due to oxidative stress. Silverside is one commercially relevant fish in Buenos Aires and a key species in the food chain in the region. Therefore, further histopathological studies are relevant to guarantee this fish’s health and safety for human consumption.Fil: Puntoriero, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; ArgentinaFil: Fernandez Cirelli, Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; ArgentinaFil: Volpedo, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; Argentin

Risk for rural population in areas with high arsenic water content

El arsénico (As) es un tóxico natural presente en aguas subterráneas y superficiales. En este trabajo se estimó el riesgo por ingesta de agua subterránea con elevadas concentraciones de As para pobladores rurales bonaerenses. Además se consideró una fuente adicional de exposición a la presencia de As en tejidos blandos del pejerrey (Odontesthes bonariensis), que es la especie nativa de mayor importancia comercial. La concentración de As se determinó por espectroscopía de emisión atómica por plasma de acoplamiento inductivo (ICP-OES). En las muestras de agua subterránea las concentraciones se hallaron en el rango de < 10-170 µg/l, mientras que en músculos de peces estuvo comprendida entre 0,29-8,41 µg/g y en hígado entre 0,24-8,98 µg/g (en peso seco). El hidroarsenicismo crónico regional endémico Argentino (HACREA), enfermedad que se origina por el consumo de cantidades variables de As en un largo período de tiempo, genera diferentes afecciones de piel. El riesgo estimado por ingesta de agua subterránea en todas las localidades estudiadas superó el valor aceptado de riesgo individual máximo (10-5), según la Agencia de Protección Ambiental de los Estados Unidos (USEPA). Los niveles de As hallados en tejidos de peces, sugieren que existiría transferencia de este elemento desde el agua a los distintos órganos, que podría resultar perjudicial para el consumo humano.Arsenic (As) is a natural toxic present in groundwater and surface water. This study estimated the risk of ingestion of high As concentrations present in groundwater for a rural population in Buenos Aires Province. The presence of As in soft tissues of silverside (Odontesthes bonariensis) was also considered as an additional source of As exposure, which is the native species of major commercial importance. Arsenic concentration was determined by inductively coupled plasma atomic emission spectroscopy (ICP-OES). In water samples As concentrations were found in the range of < 10-170 µg/l, in fish muscle the concentration range was between 0,29 to 8,41 µg/g, and in liver between 0,24 to 8,98 µg/g, of dry weight. The endemic regional chronic hydroarsenicism Argentino (ERCHA), a disease caused by consumption of varying As concentrations during a long time, generates different skin pathologies. The risk estimated for groundwater intake in this rural population at all sites studied exceeded the accepted value of maximum individual risk (10-5), according to United States Environmental Protection Agency (USEPA). As concentration in fish tissues, could be shown transference of this element to different organs, being harmful for human consumption.Fil: Puntoriero, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones En Produccion Animal; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; ArgentinaFil: Volpedo, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones En Produccion Animal; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; ArgentinaFil: Fernandez Cirelli, Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones En Produccion Animal; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; Argentin

Length-weight and length-length relationship for three marine fish species of commercial importance from southwestern Atlantic Ocean coast

Length-weight (LWR) and length-length (LLR) relationships were described for three marinefish  species  Odontesthes  argentinensis  (Valenciennes,  1835),  Urophycis  brasiliensis  (Kaup,  1858)  andBrevoortia aurea (Spix & Agassiz, 1829) from the southwestern Atlantic Ocean coast, among sampling sites between 36 and 38°S. These species have commercial importance in fisheries. Latitudinal change in LWR could suggest the existence of different subpopulations throughout their distribution ranges. A total of 2,167 specimens were collected between August 2015 and October 2018 using lift nets (mostly 10 mm mesh size) and fishing rods 100-200 m offshore. Both relationships were highly significant (P 0.94). The latitudinal trend of a and b parameters of LWR showed different patterns for each species. This study provides a new maximum length for B. aurea and describes thevariation of the regression parameters. New length-length relationships of these species were reported.Fil: Biolé, Fernanda Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; ArgentinaFil: Volpedo, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; ArgentinaFil: Thompson, Gustavo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; Argentin