Introduction: The frequent use of pesticides is currently considered a cause of environmental pollution due to the high rate of entry of these substances into agroecosystems. This constitutes a risk ...for the species that inhabit these ecosystems, in particular anurans whose characteristics make them prone to exposure to and interaction with environmental pollutants. Objective: To report the occurrence of abnormalities in larvae of the common toad Rhinella arenarum inhabiting ponds surrounded by agroecosystems. Methods: In two consecutive springs (2015 and 2016), reproductive events of common toads were monitored in temporary pond systems in agricultural and non-agricultural areas, located near the city of La Plata (Buenos Aires, Argentina). The physicochemical parameters of the ponds were measured, and the stage of each reproductive event was recorded, such as the numbers of adult toads, amplexus and clutches. In the laboratory, the larvae were measured and photographed, their stage of development was recorded, and their morphology was examined under a stereomicroscope. Representative samples (normal and abnormal) from each pond studied were processed for histopathological analysis. Results: In the field studies carried out on a population of R. arenarum collected in an agroecosystem, a lower number of reproductive adults and clutches were observed in relation to the population of a non-agricultural pond. A total of 1 910 larvae were collected: 529 and 1 381 larvae from ponds located in non-agricultural and agricultural areas, respectively. Larvae from the agroecosystem showed two types of abnormalities: severe tail flexure and abdominal bloating. In addition, five degrees of severity could be determined in relation to abdominal bloating. Conclusions: This work reports the high frequency and severity of abnormalities observed in the early stages of R. arenarum larvae living within an agroecosystem, providing evidence of the negative impact that agricultural activities cause on aquatic ecosystems surrounded by farming areas.
Abstract Introduction: The frequent use of pesticides is currently considered a cause of environmental pollution due to the high rate of entry of these substances into agroecosystems. This ...constitutes a risk for the species that inhabit these ecosystems, in particular anurans whose characteristics make them prone to exposure to and interaction with environmental pollutants. Objective: To report the occurrence of abnormalities in larvae of the common toad Rhinella arenarum inhabiting ponds surrounded by agroecosystems. Methods: In two consecutive springs (2015 and 2016), reproductive events of common toads were monitored in temporary pond systems in agricultural and non-agricultural areas, located near the city of La Plata (Buenos Aires, Argentina). The physicochemical parameters of the ponds were measured, and the stage of each reproductive event was recorded, such as the numbers of adult toads, amplexus and clutches. In the laboratory, the larvae were measured and photographed, their stage of development was recorded, and their morphology was examined under a stereomicroscope. Representative samples (normal and abnormal) from each pond studied were processed for histopathological analysis. Results: In the field studies carried out on a population of R. arenarum collected in an agroecosystem, a lower number of reproductive adults and clutches were observed in relation to the population of a non-agricultural pond. A total of 1 910 larvae were collected: 529 and 1 381 larvae from ponds located in non-agricultural and agricultural areas, respectively. Larvae from the agroecosystem showed two types of abnormalities: severe tail flexure and abdominal bloating. In addition, five degrees of severity could be determined in relation to abdominal bloating. Conclusions: This work reports the high frequency and severity of abnormalities observed in the early stages of R. arenarum larvae living within an agroecosystem, providing evidence of the negative impact that agricultural activities cause on aquatic ecosystems surrounded by farming areas.
A combined investigation by X-ray fluorescence (XRF), Fourier Transform Infrared spectroscopy (FT-IR), Raman spectroscopy and powder X-ray Diffraction (XRD), supplemented with the Rietveld analysis, ...was conducted on sixty Spanish dinosaur bone specimens from Upper Jurassic/Lower Cretaceous to Upper Cretaceous age to investigate taphonomy and diagenetic processes. The diffraction approach assessed in all specimens the presence of fluorapatite at various levels of percentage as the mineral phase constituting the fossil bone. In addition to fluorapatite, calcite and quartz were also found as main secondary phases in many specimens. The infrared spectra of fossil bones show significant changes in the phosphate and carbonate band intensity with respect to a non-fossil bone. Conversely, the X-ray fluorescence spectra turned out to be mainly dominated by the presence of Ca, obviously accompanied by phosphorus. Simultaneously, other elements accompanying Ca, such as Fe and Sr were found at significant concentration levels.
A considerable amount of Fe and Sr ions were incorporated in the structure of fluorapatite, but when their concentration was found elevated in the fluorescence spectrum, the diffraction data revealed the presence of goethite (FeOOH) and celestite (SrSO
4) phases. While the X-ray diffraction phase analysis also revealed the presence of kaolinite, dolomite, barite and gypsum, in some fluorescence spectra further elements like Y, As, Pb, Ti, Mn, Cr, Cu, Zn were present in concentration at trace level. The introduction/substitution of new elements with the infiltration of new phases due to diagenesis is also affecting to various extent the Raman and FT-IR spectra with modification of some bands and/or the appearance of new bands. The average crystallite size of the “apatitic” constituent phase was found to vary from a minimum of ca. 183
Å to an upper level of 2107
Å. No systematic relation between apatite crystallite size and age of the dinosaur bones was found that suggests a high variability of diagenetic processes affecting the growth of bone crystallites even in the same site.
► We have used a multiple-technique approach to investigate a collection of Spanish dinosaur bone specimens to characterize the fossilization in terms of physico-chemical and mineralogical composition. ► The most frequent phases in the samples studied are mostly fluorapatite, quartz and calcite. ► The X-ray diffraction analysis also revealed the presence of kaolinite, dolomite, barite, celestite, gypsum an berlinite phases. ► The average crystallite size of the apatite-like phase varies unpredictably in the analysed specimens, inhibiting a correlation with fossil age.
