Isotopic discrimination of stable isotopes of nitrogen (δ15N) and carbon (δ13C) in a host-specific holocephalan tapeworm

5 pages, 2 figures, 1 tableDuring the past decade, parasites have been considered important components of their ecosystems since they can modify food-web structures and functioning. One constraint to the inclusion of parasites in food-web models is the scarcity of available information on their feeding habits and host–parasite relationships. The stable isotope approach is suggested as a useful methodology to determine the trophic position and feeding habits of parasites. However, the isotopic approach is limited by the lack of information on the isotopic discrimination (ID) values of parasites, which is pivotal to avoiding the biased interpretation of isotopic results. In the present study we aimed to provide the first ID values of δ15N and δ13C between the gyrocotylidean tapeworm Gyrocotyle urna and its definitive host, the holocephalan Chimaera monstrosa. We also test the effect of host body size (body length and body mass) and sex of the host on the ID values. Finally, we illustrate how the trophic relationships of the fish host C. monstrosa and the tapeworm G. urna could vary relative to ID values. Similar to other studies with parasites, the ID values of the parasite–host system were negative for both isotopic values of N (Δδ15N = − 3.33 ± 0.63‰) and C (Δδ13C = − 1.32 ± 0.65‰), independent of the sex and size of the host. By comparing the specific ID obtained here with ID from other studies, we illustrate the importance of using specific ID in parasite–host systems to avoid potential errors in the interpretation of the results when surrogate values from similar systems or organisms are usedJ.N. and M.C. were supported by research contracts of the Juan de la Cierva program and Ramon y Cajal (Spanish Ministry of Economy and Competitiveness), respectivelyPeer reviewe

Emerging organic contaminants in groundwater : a review of sources, fate and occurrence

Emerging organic contaminants (EOCs) detected in groundwater may have adverse effects on human health and aquatic ecosystems. This paper reviews the existing occurrence data in groundwater for a range of EOCs including pharmaceutical, personal care, ‘life-style’ and selected industrial compounds. The main sources and pathways for organic EOCs in groundwater are reviewed, with occurrence data for EOCs in groundwater included from both targeted studies and broad reconnaissance surveys. Nanogram-microgram per litre concentrations are present in groundwater for a large range of EOCs as well as metabolites and transformation products and under certain conditions may pose a threat to freshwater bodies for decades due to relatively long groundwater residence times. In the coming decades, more of these EOCs are likely to have drinking water standards, environmental quality standards and/or groundwater threshold values defined, and therefore a better understanding of the spatial and temporal variation remains a priority

Creative geographies of ceramic artists: knowledges and experiences of landscape, practices of art and skill

This paper argues for a conception of art as an embodied and creative material practice. It draws on research conducted with seven professional ceramic artists who deal with landscape in their work to explore their processes of art-making through interview and (filmed) observation. It demonstrates the distributed range of embodied and relational more-than-artistic practices which inform how landscape is encountered, known and ultimately represented. It argues that artists’ self-expression in art is based upon material, social and political knowledges which interweave in artists’ lives. By studying ceramicists’ making this paper demonstrates both the non-conscious skill and the conscious technical knowledge needed to make art. It shows chance to have a triple role in practices of making, as something to work alongside, to work against and to draw on as a creative resource. This paper both argues for and demonstrates the value of an approach to art-making that frames it as a complex of both conscious, socio-cultural, technical knowledges and non-conscious skills which together (in)form works of (ceramic) art