Structure of wetland-breeding anuran assemblages from the southern section of the Paraná river, Argentina

Knowledge of anuran reproduction is necessary to understand the organization of their communities and is a first step in developing management strategies in order to conserve amphibian diversity. We studied the reproduction of anuran species in a wetland reserve – Pre-Delta National Park (PDNP) – on the southern section of the Paraná river in the mideastof Argentina, examining its structure at temporal and spatial levels. We also analysed the influence of environmental factors on breeding activities at habitat and landscape levels. Six waterbodies in the PDNP were monitored from September 2005 to March 2006. Five habitat variables (maximum pond width and length, maximum depth, shore vegetation and presence of predators) and three landscape variables (monthly air temperature, river level and rainfall) were recorded every month and analysed through multivariate analysis. Principal coordinate analysis (PCoA) indicated the existence of four breeding periods. The most frequent breeding call location was the edge of a pond (56.8%), over floating and marsh plants. The presence of tadpole predators and pond width were the main habitat variables that influenced breeding activities. In addition, the number of species with calling males per month was positively correlated with the level of the river which supplies water to ponds. Breeding anuran species co-occurred less often than expected by chance, and exhibited breeding segregation at temporal and spatial scales. The diverse evidence regarding temporal and spatial breeding activities demonstrates the importance of segregation for anuran reproduction in the area studied. We suggest that the nature of breeding interactions can be affected by habitat preference and reproductive strategy, as well as by abiotic (e.g. pond width), biotic (e.g. predators) and landscape (e.g. hydrological variation) variables.Fil: Sanchez, Laura Cecilia. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; ArgentinaFil: Peltzer, Paola. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Escuela Superior de Sanidad; ArgentinaFil: Lajmanovich, Rafael Carlos. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Escuela Superior de Sanidad; Argentin

Feeding habits of Physalaemus biligonigerus (Anura, Leptodactylidae) from soybean field of Córdoba Province, Argentina

Detailed investigation of feeding habits in anurans may help us to understand the ecological significance of them in a particular habitat. In this sense, diet composition of anuran living inside soybean field is scarce. We examined the diet of Physalaemus biligonigerus in soybean field of Córdoba Province, Argentina. A total of 27 frogs (n = 14 females and n = 13 males) were analyzed to assess gastrointestinal contents. Indeed, snout vent length, body mass and sexes were also recorded. A total of 418 prey items was found, being Pheidole sp. (Hymenoptera, Formicidae) and Armadillium vulgare (Crustacea, Isopoda) the most important preys. The diet composition of frog was compared with prey relative abundance in soybean field, estimated by pitfall traps. There were no significant correlation (ô = 0.48, p > 0.05). Selectivity analysis showed positive values for Formicidae and Isoptera. Thus, Isopoda was consumed in the same proportion as occurrence in the environment. No significant differences were detected between females and males diet composition. Finally, we suggest that P. biligonigerus should be considered as potential biocontrol agents of noxious arthropods in soybean field.Fil: Attademo, Andres Maximiliano. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Peltzer, Paola. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lajmanovich, Rafael Carlos. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Inhibition and recovery of cholinesterases in Odontophrynus americanus tadpoles exposed to fenitrothion

We determined the levels of brain acetylcholinesterase (AChE) and tail butyrylcholinesterase (BChE) activities in tadpoles of Odontophrynus americanus exposed to a commercial formulation of fenitrothion. The mean brain AChE activities in the controls tadpoles varied from 6.91 to 6.39 µmol min-1 mg-1 protein, whereas tail BChE activities ranged among 0.26 to 0.17 µmol min-1 mg-1 protein; the two sub- lethal concentrations of fenitrothion assayed produced AChE and BChE inhibition (p < 0.01). Brain AChE recovered a substantial level of activity with a maximum of 93.2%; after the transference of tadpoles to a free-pesticide solution, whereas tail BChE recovery showed a smaller increase (39%) in the activity at 168 hr after to transference to clear water. According with our results, we suggest that tadpole’s tail BChE presents higher sensibility than brain AChE.Fil: Lajmanovich, Rafael Carlos. Universidad Nacional del Litoral; ArgentinaFil: Attademo, Andres Maximiliano. Universidad Nacional del Litoral; ArgentinaFil: Peltzer, Paola. Universidad Nacional del Litoral; ArgentinaFil: Junges, Celina Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; Argentin

Acute Toxicity and Sublethal Effects Caused by a Commercial Herbicide Formulated with 2,4-D on Physalaemus albonotatus Tadpoles

The aim of this study was to evaluate the acute and chronic effects caused by exposure to the 2,4 dichlorophenoxyacetic acid (2,4-D)-based commercial herbicide Amina Zamba® on Physalaemus albonotatus tadpoles from Gosner stage 25. The lethal concentration (LC50) was determined after exposure to different concentrations of Amina Zamba® (350 to 2400 mg/L) at 96 h. Sublethal effects were evaluated after chronic exposure to four fractions of the LC50 96h obtained (12.5, 25, 50, and 75% of LC50 96h ) and a control. The biological responses analyzed included survival, growth and development, morphological abnormalities, and histological changes in the liver. The LC50 values of Amina Zamba® at 48, 72, and 96 h were 1040.2, 754.2, and 350 mg/L, respectively. The chronic exposure to the herbicide altered the survival of exposed tadpoles and caused several morphological abnormalities and liver histological alterations, mainly at the highest concentrations tested. Oral disc malformations and intestinal abnormalities were the most frequent abnormalities in all treated tadpoles. Histological alterations observed in the liver structure included hepatocyte vacuolization, enlargement of sinusoids, dilation of blood vessels, and a significant increase in the number of melanomacrophages in tadpoles exposed to 25, 50, and 75% LC50 96h with respect to control (P < 0.05). Furthermore, the treated tadpoles showed an accelerated development rate, reaching Gosner stages 38 and 42 before controls. These results demonstrate that the chronic exposure to this commercial formulation affects the survival, accelerates metamorphosis, and induces morphological abnormalities and liver damage in P. albonotatus tadpoles.Fil: Curi, Lucila Marilén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias. Laboratorio de Ecotoxicologia; ArgentinaFil: Peltzer, Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias. Laboratorio de Ecotoxicologia; ArgentinaFil: Sandoval, María Teresa. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas, Naturales y Agrimensura. Departamento de Biología; ArgentinaFil: Lajmanovich, Rafael Carlos. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias. Laboratorio de Ecotoxicologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentin

Albinism in larvae of the Chacoan frog <i>Leptodactylus chaquensis</i> (Anura, Leptodactylidae) from an urban lake from Argentina

We report complete albinism in Leptodactylus chaquensis (Cei, 1950; Amphibia, Anura) larvae. Two foam nests were collected from an urban lake and maintained in outdoor tanks during metamorphosis. Different proportions of albino larvae and metamorphs occurred. This is the first observation of several larvae of L. chaquensis with albinisms from an urban lake with continuous artificial and natural luminosity.Asociación Herpetológica Argentina (AHA

Albinism in larvae of the Chacoan frog <i>Leptodactylus chaquensis</i> (Anura, Leptodactylidae) from an urban lake from Argentina

We report complete albinism in Leptodactylus chaquensis (Cei, 1950; Amphibia, Anura) larvae. Two foam nests were collected from an urban lake and maintained in outdoor tanks during metamorphosis. Different proportions of albino larvae and metamorphs occurred. This is the first observation of several larvae of L. chaquensis with albinisms from an urban lake with continuous artificial and natural luminosity.Asociación Herpetológica Argentina (AHA

Efecto del ruído del tráfico en la vocalización de machos de Scinax nasicus (Amphibia, Anura)

El aumento de los sonidos de origen antropogénico, como los ruidos del tráfico, contribuyen a la contaminación acústica, que produce un efecto nocivo en el canto de los vertebrados. Comparamos la vocalización de machos de Scinax nasicus (Cope, 1862) en ambientes naturales (como referencia o control, Sitio A) y sitios afectados por ruidos de tráfico (Sitio B). La estructura de la vocalización se registró y amplificó en sonogramas (software Raven Pro 1.5). Se midieron siete variables de su vocalización: duración (s), número de notas, número de pulsos por nota, frecuencia máxima, mínima y dominante (kHz) y amplitud (dB). Además, en cada sitio se midió el ruido de fondo (frecuencia fundamental, la F0 y amplitud, dB). La amplitud del ruido de fondo alcanzó valores más altos (68.02 dB) en el Sitio B, en el Sitio A fue menor (34.81 dB). Por lo tanto, el F0 en el Sitio A fue de 6.28 kHz y en el Sitio B fue de 4.15 kHz. Las vocalizaciones de esta rana en el ambiente con ruido de tráfico (Sitio B) se caracterizaron por menor duración (s) y número de pulsos por nota, mayor amplitud (dB) y frecuencias máximas y dominantes más altas (kHz), baja frecuencia mínima en comparación con el ambiente control (Sitio A). Nuestro estudio resaltó que los machos de S. nasicus cambian su estructura vocal en estanques de ruido de tráfico, principalmente por “ajuste” vocal de sus frecuencias y amplitud para contrarrestar el efecto de enmascaramiento del ruido. Finalmente, el monitoreo acústico de anuros en ambientes ruidosos debe considerar el solapamiento espacial, temporal y espectral entre ruido acústico específico y el comportamiento de la especie.Increased anthropogenic-made sounds such as traffic noises contribute to acoustic pollution, which produces deleterious effect on songvertebrates. We compared the advertisement call of Scinax nasicus (Cope, 1862) males in natural (as a reference or control, Site A) and Sites affected by traffic noises (Site B). Call structure was recorded and it was amplified in sonograms (software Raven Pro 1.5). Seven variables were measured on its advertisement call: duration (s), number of notes, number of pulses per note, maximum and minimum frequency (kHz), dominant frequency (kHz) and amplitude (dB). In addition, at each Site the background noise (the fundamental frequency, F0 and amplitude, dB) was measured. The amplitude of background noise reached higher values (68.02 dB) in Site B, while in Site A was lower (34.81 dB). Thus, the F0 in Site A was 6.28 kHz and in Site B it was 4.15 kHz. Frog call in noisy environment (Site B) were characterized by lesser duration (s) and number of pulses per note, higher maximum and dominant frequencies (kHz), lower minimum frequencies, and amplitude (dB) when compared with control environment (Site A). Our study highlights, that S. nasicus males shift their vocal structure in traffic noisy ponds, mainly by vocal “adjust” of their frequencies and amplitude to counteract masking effect. Finally, acoustic monitoring of anurans on noise environments should be considering the spatial, temporal and spectral overlap between noise and species-specific acoustic behaviour.Fil: Leon, Evelina Jesica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Peltzer, Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Laboratorio de Saneamiento Ambiental. Cátedra de Ecotoxicología; ArgentinaFil: Lorenzón, Rodrigo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Lajmanovich, Rafael Carlos. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Laboratorio de Saneamiento Ambiental. Cátedra de Ecotoxicología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Beltzer, Adolfo Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentin

Blood biomarkers of common toad Rhinella arenarum following chlorpyrifos dermal exposure

Chlorpyrifos (CPF) is a broad spectrum pesticide commonly used for insect control, has great affinity for lipids and is thus a potential for bioaccumulation in aquatic organisms. The aim of this study was to evaluate the toxicity of CPF using the common toad Rhinella arenarum via dermal uptake in plastic bucket to simulate their natural exposition in ponds. R. arenarum toads were exposed individually to solutions containing a nominal concentration of a commercial formulation of CPF insecticide (5 and 10 mg/L). Different enzyme biomarkers (BChE: butyrylcholinesterase, CbE: carboxylesterase, and CAT: catalase) were measured in blood tissue after exposition. The capacity of pyridine-2-aldoxime methochloride (2-PAM) to reverse OP-inhibited plasma BChE and the ratio of heterophils and lymphocytes (H/L) as hematological indicators of stress were also determined. The normal values of plasma B-sterases (BChE and CbE) were highly inhibited (until ≈ 70%) in toads 48 h after exposure to CPF. The results indicate that 2-PAM produced BChE reactivation as well. The activity of CAT was also inducted for dermal exposure at more than double of that in the control toads (CPF; 5 mg/L). H/L ratios did not reveal a significantly increased stress. The study suggests that CPF via dermal uptake induced neurotoxicity and oxidative stress in the common toad R. areanum. Thus, some blood biomarkers employed in our study (i.e. BChE, CbE, 2-PAM, and CAT) might be used as predictors in health and ecological risk assessment of amphibian populations exposed to CPF.Fil: Lajmanovich, Rafael Carlos. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Laboratorio de Saneamiento Ambiental. Cátedra de Ecotoxicología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Peltzer, Paola Mariela. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Laboratorio de Saneamiento Ambiental. Cátedra de Ecotoxicología; ArgentinaFil: Attademo, Andres Maximiliano. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Laboratorio de Saneamiento Ambiental. Cátedra de Ecotoxicología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Colussi, Carlina Leila. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Laboratorio de Saneamiento Ambiental. Cátedra de Ecotoxicología; ArgentinaFil: Martinuzzi, Candela Soledad. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Laboratorio de Saneamiento Ambiental. Cátedra de Ecotoxicología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentin

Reproductive activity of anurans in a dominant agricultural landscape from central-eastern Argentina

Agriculture can modify natural systems through habitat loss and fragmentation, as well as through the effect of agrochemicals on biological traits such as reproduction. We studied anuran diversity and reproduction of assemblages from 3 sites with different degrees of agricultural activities (an agroecosystem, a transitional area, and a natural forest) located in Entre Ríos province (Argentina). We conducted several field surveys during 2 soybeancropping periods from November 2006 to April 2008. A total of 23 anuran species were identified. Richness, evenness and diversity differed among sites. No range-abundance models were statistically adequate to describe the distribution of abundances within the agroecosystem, whereas the anuran species from the other 2 sites fitted the normal logarithmic model. The location and substrates used for nuptial calling in ponds, as well as the reproductive periods of anuran species varied among sites. These findings might respond to a combination of factors, such as anuran composition, species abundances, availability of reproductive microhabitats, and variation of microclimatic characteristics among sites, the agroecosystem being the most different anuran reproductive community. Finally, our results suggest that agricultural land use have adverse effects on the reproduction of anurans in central-eastern Argentina.La agricultura puede modificar los sistemas naturales mediante la fragmentación y pérdida de hábitat, como también debido al efecto de los agroquímicos sobre rasgos biológicos tales como la reproducción. Se estudió la diversidad y la reproducción en 3 comunidades de anuros provenientes de sitios con distintos grados de actividad agrícola (un agroecosistema, una área de transición y un bosque natural) de la provincia de Entre Ríos (Argentina). Se realizaron inspecciones a campo durante 2 periodos entre la siembra y la cosecha de soja, desde noviembre de 2006 hasta abril de 2008. Se identificaron 23 especies de anuros. La riqueza, la equitatividad y la diversidad difirieron entre sitios. La distribución de abundancias dentro del agroecosistema no se ajustó a ningún modelo rango-abundancia. La ubicación y los sustratos utilizados para vocalizar por las especies como también sus periodos reproductivos variaron entre sitios. Estos resultados podrían responder a una combinación de factores tales como composición de anuros, abundancia de las especies, disponibilidad de microhabitats reproductivos y variaciones microclimáticas entre sitios, siendo el agroecosistema la comunidad reproductiva más diferente. Finalmente, se sugiere que el uso de la tierra para la agricultura tendría efectos adversos sobre la reproducción de los anuros en el centro-este de Argentina.Fil: Sanchez, Laura Cecilia. Universidad Nacional del Litoral. Facultad de Bioquimica y Ciencias Biologicas. Escuela Superior de Sanidad; Argentina;Fil: Peltzer, Paola. Universidad Nacional del Litoral. Facultad de Bioquimica y Ciencias Biologicas. Laboratorio de Saneamiento Ambiental; Argentina;Fil: Lajmanovich, Rafael Carlos. Universidad Nacional del Litoral. Facultad de Bioquimica y Ciencias Biologicas. Escuela Superior de Sanidad; Argentina;Fil: Manzano, Adriana Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico y Transferencia de Tecnologia A la Producción; Argentina;Fil: Junges, Celina Maria. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Laboratorio de Saneamiento Ambiental; Argentina;Fil: Attademo, Andres Maximiliano. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Laboratorio de Saneamiento Ambiental. Cátedra de Ecotoxicologia; Argentina