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09/02/2010
The negative effects of pollution on amphibians are especially high when animals are additionally stressed by other environmental factors such as water salinity. The combined effect of a common fertilizer, ammonium nitrate and water salinity was tested on embryos of two Pelophylax perezi populations from ponds with different salinity concentrations. Embryos exposed to the fertilizer were up to 17% smaller than controls. Survival rates of embryos exposed to a single stressor were always below 10%. The exposure to both stressors concurrently increased mortality rate of embryos from freshwater. The fertilizer was lethal only when individuals were stressed by the salinity, not having lethal effects on embryos naturally adapted to saline environments. These results underscore the importance of testing multiple stressors when analyzing amphibian sensitivity to environmental pollution. More info: Ortiz-Santaliestra (2010). Adaptation to osmotic stress provides protection against ammonium nitrate in Pelophylax perezi embryos. Environm Pollution 158: 934–940. Doi:10.1016/j.envpol.2009.09.011
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05/02/2010
Although micro-organisms represent a majority and play pivotal roles in community development and function, the study of the factors influencing the assembly of microbial communities has lagged behind. The mechanisms accounting for the low species richness of yeast communities inhabiting the nectar of the bumble-bee-pollinated Helleborus foetidus were investigated. Results show that nectar filtering leads to species-poor, phylogenetically clustered yeast communities that are a predictable subset of pollinator-borne inocula. Such strong habitat filtering is probably due to H. foetidus nectar representing a harsh environment for most yeasts, where only a few phylogenetically related nectar specialists physiologically endowed to tolerate a combination of high osmotic pressure and fungicidal compounds are able to develop. More info: Herrera et al (2010). Inhospitable sweetness: nectar filtering of pollinator-borne inocula leads to impoverished, phylogenetically clustered yeast communities. Proc. R. Soc. B (2010) 277, 747–754 doi:10.1098/rspb.2009.1485
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03/02/2010
Geolocators were used to investigate the effect of extra mass on the pelagic behavior of Cory’s Shearwaters (Calonectris diomedea). The extra mass increased the duration of the birds’ trips and decreased their foraging efficiency and mass gained at sea. These indirect effects may be related to foraging traits: weighted birds showed a greater search effort than control birds, traveled greater distances, covered a greater foraging area, and increased the maximum foraging range. Furthermore, the time spent on the sea surface at night was greater for weighted than for control groups. These results underline the need to quantify the effects of monitoring equipment commonly used to study the pelagic behavior of seabirds. Geolocators can be used to obtain control data on foraging-trip movements and activity patterns. More info: Passos et al (2010) Effects of Extra Mass on the Pelagic Behavior of a Seabird. The Auk 127:100-107. DOI: 10.1525/auk.2009.09036
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