Agriculture practices have been widely proposed as the major cause of amphibian population decline. However, the majority of these results have been based on laboratory experiments. The present study was conducted to test the repercussion of wetland sediment provenance on amphibian larval development. Bufo bufo larvae were used in two different treatments in an outdoor experiment, the first one using sediment from one wetland surrounded by intensive agricultural practices, and the second using sediment with no record of agrochemical uses. A negative effect was observed in the agricultural treatment, from subcellular to individual level. The results showed that the sediment from agricultural practices watershed generates a reduction in survival. Furthermore, individuals that developed under this treatment showed a lower total length and a delay in the time necessary to complete metamorphosis; these features are connected with recruitment success. In the same way, biochemical analysis showed high values of lipid peroxidation in metamorphs developing in sediments from an agricultural area. Finally, the results obtained highlight the importance of considering the sediments, not only the water, as origin treatment, allowing us to understand the consequences on amphibian populations that inhabit areas affected by intensive agriculture.
The most heavily glacierized tropical range in the world – the Peruvian Cordillera Blanca-has been losing ice since the end of the Little Ice Age(LIA). In this study, the decline of the Churup glacier(9°28'18 " S; 77°25'02" W) and associated processes were documented employing multi-proxy approach including the analysis of remotely sensed images(1948-2016), the Schmidt hammer rock test and lichenometric dating. It is shown that Churup glacier has lost the vast majority of its estimated LIA extent(1.05 ± 0.1 km~2; 45.0×10~6-57.4×10~6 m~3). The rate of glacier retreat is documented to vary in space(SE, SW and NW-facing slopes) and time, with the peak between 1986 and 1995. With an area of 0.045 km~2 in 2016, it is expected that the complete deglaciation of the Churup valley is inevitable in the near future. Recently(post-LIA) exposed bedrock surfaces have shown higher R-values(54.2-66.4, AVG 63.3, STDEV 2.9) compared to pre-LIA exposed surfaces(46.1-59.3, AVG 50.1, STDEV 4.9), confirming the links to the duration of rock weathering. The Lichenometric dating is applied to recently exposed areas and elevations above 4800 m a.s.l., revealing only limited reliability and agreement with the age of deglaciation estimated from remotely-sensed images in such an environment. 相似文献
The purpose of this research was to investigate the relationship between soil biota such as microbial activity, soil fauna(e.g., earthworms and enchytraeids), and soil physical and chemical properties. The study area was located in Pieniny National Park(PNP) in the Carpathian Mountains in southern Poland. Soil samples were collected from six forest monitoring areas of PNP from two soil layers(at 0–15 cm and 15–30 cm down, respectively). The investigated soils were classified to eutric cambisols and had silt or silt loam soil texture. Upon analysis, soil aggregate stability index was connected with other physical, chemical, and biological soil properties.It was noted that the stability index of 3 mm to 5 mm soil aggregates influenced pH and dissolved organic carbon. The stability index of 2 mm to 3 mm soil aggregates was positively correlated with dissolved organic carbon, soil moisture, microbial biomass carbon, total organic carbon, total nitrogen, and enchytraeid density, and negatively correlated with bulk density, particle density, porosity, and permanent wilting point. The stability index of 1 mm to 2 mm soil aggregates was positively correlated with total nitrogen, enchytraeid and earthworm density and negatively correlated with particle density, porosity, and permanent wilting point. The study has shown what factors create a stable soil structure in the forest soils of PNP. 相似文献
The study reports photometric and spectroscopic observations of two recently recognized contact binary systems.Both systems show total eclipses and analysis of the light curves indicates both have very low mass ratios of less than 0.3. We derive absolute parameters from color and distance based calibrations and show that, although both have low mass ratios, they are likely to be in a stable orbit and unlikely to merge. In other respects, both systems have characteristics similar to other contact... 相似文献
<正>A new fossil chironomid,Tanytarsus serafini,found in Baltic amber is described and illustrated based on adult males.The new species and similar extant species of the genus Tanytarsus van der Wulp are compared. Due to several distinct characters of wing,legs and hypopygium,a new species group for Tanytarsus serafini is proposed,and its diagnostic features are evaluated. 相似文献
<正>Fossil water scavenger beetles(Coleoptera:Hydrophilidae)of the latest Oligocene Rott Formation are revised,based on the examination of the type specimens,as well as numerous additional material from Statz(Los Angeles)and Kastenholz(Bonn)collections.Seven hydrophilid species are recognized,five of which are reliably attributed to the following genera:Berosus morticinus(von Heyden and von Heyden,1866),Paracymus excitatus (von Heyden and von Heyden,1866),Paracymus sp.,Hydrobiomorpha fraterna(von Heyden,1859),and Hydrophilus rottensis(Statz,1939).Coccinella? protogaeae Germar 1837 is attributed to the subtribe Hydrophilina, and Cymbiodyta? austera Statz 1939 to the subfamily Hydrophilinae.Hydrous ebeninus Statz 1939 and Paracymus excitatus(form 3)are excluded from the Hydrophiloidea.Berosus capitatus Statz 1939 is synonymized with Berosus morticinus,and Hydrous neptunus von Heyden and von Heyden 1866 with Hydrobiomorpha fraterna.Lectotypes of Philydrus morticinus von Heyden and von Heyden 1866 and Hydrous ebeninus Statz 1939 are designated.The significance of the hydrophilid fossils for paleoecological reconstructions of the former Rott Lake is briefly discussed. 相似文献