Integrated assessment of the effects posed by historical exposure to chemical contamination in natural populations of the Perez’s frog, Pelophylax perezi (Seoane, 1885)

Resumen del trabajo presentado al 6th SETAC World Congress and SETAC Europe 22nd Annual Meeting of the Society of Environmental Toxicology and Chemistry, celebrados en Berlin (Alemania) del 20 al 24 de mayo de 2012.-- et al.Most works assessing the effects that chemical contamination may pose to amphibians have been centered on laboratory assays with organisms originated from nonimpacted populations. However, amphibians may respond differently when exposed to contaminants in field or in laboratory. In addition, more holistic and integrated studies are essential to promote ecological relevance of generated knowledge. This work aimed at an interdisciplinary assessment of the effects caused by a long-tem exposure to chemical contamination on adults of Pelophylax perezi. For this, four populations were sampled: two at chemically contaminated sites and two at reference sites. Sixteen adult organisms (8 females; 8 males) were captured at each site and transported chilled to the laboratory, where were euthanized with MS222 and its morphometric parameters measured. Afterwards organisms were dissected to collect gonads, kidney, liver, muscles, spleen, lungs and bones, which were deep frozen for posterior analysis. For each organism, biomarkers of oxidative stress (catalase, glutathione S transferase, lactate dehydrogenate) and endocrine disruption (vitellogenin-VTG), metallothioneins (MT), molecular markers, histological effects and metal levels in tissues were analyzed. Chemical analysis of surface waters revealed higher values of some elements (B, Be, Ca, K, Li, Mg, Mn, Na, Sr) at the contaminated sites comparatively with the reference ones. Metal analyses in sediment, soil and tissue samples are still being processed. Significant differences in enzymatic activities and in VTG levels were detected among the four populations, but could not be associated with different levels of the metal contamination in water. Histological analysis on male gonads revealed testicular oocytes (TO) in the impacted populations (25% and 12.5%) while no TO were detected in reference populations. Differences in the mean seminiferous lobule (MSL) diameter were observed between reference and contaminated populations, and as well between the two contaminated populations. Analysis of MT and histology of spleen, liver, lungs and kidney are underway. Also, the genetic diversity within and between populations is being addressed using a combination of neutral, non-neutral, genomic and mitochondrial DNA markers. All these data will be integrated and presented in the poster.Peer reviewe