RESUMO
El test de micronúcleos (MN) es un biomarcador de genotoxicidad no destructivo que permite detectar daño cromosómico y otras alteraciones nucleares (AN). Phrynops hilarii es un quelonio de agua dulce que habita regiones del centro-norte de Argentina. El objetivo principal fue determinar la presencia de MN y otras AN en eritrocitos de poblaciones naturales de P. hilarii comparando sus frecuencias entre tres sitios, dos antropizados y uno de control (ciudades de Diamante y Paraná) de Entre Ríos, Argentina, durante el periodo 2015-2016. Dieciocho individuos (seis por sitio de muestreo) fueron evaluados en los sitios: 1- PD: Parque Nacional Pre-Delta (control), 2- AG: Salto Ander Egg (agroecosistema) y 3- SU: Caleta Club Náutico (sistema urbano). Se extrajo sangre de la vena femoral. Las muestras se tiñeron con el método May Grünwald-Giemsa y se observaron bajo un microscopio con el objetivo de inmersión. Las frecuencias de micronúcleos (FMN) y alteraciones nucleares (FAN) se determinaron cada 1000 eritrocitos observados. Se encontró diferencia significativa (p<0,05) entre el sitio PD y los otros sitios (AG y SU), tanto para FMN (p=0,0021) como para FAN (p=0,0011). Los valores de las frecuencias más altos correspondieron al sitio AG (FMN: 3,33±0,62; FAN: 4,67±0,56). Finalmente, el biomonitoreo con P. hilarii fue útil, por lo que podría considerarse como especie bioindicadora para evaluar la calidad de los ambientes de Argentina.
The micronucleus test (MN) is a biomarker of non-destructive genotoxicity that allows chromosomal damage and other nuclear alterations (NA) to be detected. Phrynops hilarii is a freshwater chelonium that inhabits regions of central-northern Argentina. The main objective was to determine the presence of MN and other NA in erythrocytes of natural populations of P. hilarii comparing their frequencies between three sites, two anthropized and one of control (cities of Diamante and Paraná) of Entre Ríos, Argentina, during the period 2015-2016. Eighteen individuals (six per sampling site) were evaluated at the sites: 1- PD: Pre-Delta National Park (control), 2- AG: Salto Ander Egg (agroecosystem) and 3- SU: Caleta Club Náutico (urban system). Blood was obtained from the femoral vein. The samples were stained with the May Grünwald-Giemsa method and observed under a microscope with an immersion objective. Micronucleus (MNF) and nuclear alterations (NAF) frequencies were determined every 1000 erythrocytes observed. A significant difference (p<0.05) was found between the PD site and the other sites (AG and SU), both for MNF (p=0.0021) and for NAF (p=0.0011). The highest frequency values corresponded to the AG site (MNF: 3.33 ± 0.62; NAF: 4.67 ± 0.56). Finally, biomonitoring with P. hilarii was useful, so it could be considered as a bioindicator species to assess the quality of Argentina's environments.
RESUMO
Contamination of aquatic systems is a major environmental stress that can interfere with predator-prey interactions, altering prey or predator behavior differentially. We determined toxicity parameters of the fungicide trifloxystrobin (TFS) and examined its effects on predation rate, using a fish predator (Synbranchus marmoratus) and four anuran tadpole species as prey (Rhinella arenarum, Physalaemus santafecinus, Leptodactylus latrans, and Elachistocleis bicolor). TFS was not equally toxic to the four tadpole species, E. bicolor being the most sensitive species, followed by P. santafecinus, R. arenarum, and L. latrans. Predation rates were evaluated using different treatments that combined predator and prey exposed or not to this fungicide. TFS would alter the outcome of eel-tadpole interaction by reducing prey movements; thus, prey detection would decrease and therefore tadpole survival would increase. In addition, eels preyed selectively upon non-exposed tadpoles avoiding the exposed ones almost all throughout the period evaluated. Predation rate differed among prey species; such differences were not due to TFS exposure, but to interspecific differences in behavior. The mechanism that would explain TFS-induced reduction in predation rates remains unclear; however, what is clear is that sublethal TFS concentrations have the potential to alter prey behavior, thereby indirectly altering predator-prey interactions. In addition, we consider that predator-prey relationships are measurable responses of toxicant exposure and provide ecological insight into how contaminants modify predator-prey interactions.