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We examined parasite populations and communities in the Mediterranean sentinel fish species, Mullus barbatus, sampled at a small-scale PCB gradient at the shelf sediments off Catalonian coasts of the Western Mediterranean. A recurrent feature at both the population and community level was the differentiation of the samples along the increasing PCB levels simultaneously registered in the sediments. Both directly transmitted ectoparasites and endoparasites with complex life-cycles transmitted via food chains exhibited a decrease in abundance with the increase in PCB levels. Parasite numerical responses translated into significant differences in infracommunity structure with decreasing predictability associated with increasing PCB levels. The abundance of two species, the specialist Opecoeloides furcatus and the generalist nematode Hysterothylacium fabri, contributed substantially to the observed dissimilarity between infracommunity samples along the gradient. The observed parasite responses to moderate levels of pollution were simultaneously validated by both chemical monitoring and effect biomarkers.  相似文献   
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A common practice in archaeomagnetic studies in many laboratories is the impregnation of the material with water glass (siliceous gel) in order to achieve better consolidation before cutting. The purpose of this study is to establish if and how the presence of water glass in the burnt clay material affects its magnetic properties during heating. We describe experiments designed to monitor the alterations in isothermal remanence and magnetic susceptibility for two sets of specimens - non-impregnated and impregnated with water glass. Our results show that water glass can cause considerable changes in magnetic susceptibility, but the remanent magnetization is not influenced significantly.  相似文献   
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Environmental pollution affects parasite populations and communities, both directly and through effects on intermediate and final hosts. In this work, we present a comparative study on the structure and composition of metazoan parasite communities in the bogue, Boops boops, from two localities (Galician coast, Spain) affected by the Prestige oil-spill (POS). We focus on the distribution of both individual parasite species and larger functional groupings by using both univariate and multivariate analyses. Our results indicate directional trends in community composition that might be related to the Prestige oil-spill disturbance of the natural coastal communities off Galicia. Endoparasite communities in B. boops reflected a notable change in the composition and abundance of the benthic fauna in the localities studied post-spill probably due to organic enrichment after the POS.  相似文献   
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