Age and sexual differences in the exploitation of two anthropogenic food resources for an opportunistic seabird

The availability of food resources has been suggested as a major factor in the substantial increase in reproductive output, survival, recruitment and, ultimately, population growth rates in most organisms. In fact, the artificial increase in food availability resulting from human activities has been suggested as a factor in the substantial increase in population size of several seabirds in recent decades. In the present study, our primary aim was to estimate the importance of the main natural prey and two alternative feeding resources, fishery discards and the invasive American crayfish Procambarus clarkii, for an opportunistic seabird, the Audouin’s gull Larus audouinii. We also assessed the influence of age and sex in the use of those three types of food. For this purpose, we compared the analyses of δ¹⁵N and δ¹³C in blood of male and female adults of known age and chicks with those in their potential prey. Our results reveal sex-related and age-related differences in the consumption of fish discards, small pelagic fish and American crayfish. Differences in the diet of males and females and also between adults and chicks could be related to different nutritional requirements. Age differences were probably related to their different foraging proficiency and the tendency of young breeders to opportunistically exploit anthropogenically derived food. This study illustrates the importance of considering the age and sex of individuals to obtain feasible dietary information and to understand how the exploitation of food of human origin could affect population growth.     

Antibiotic Resistance Due to Modern Agricultural Practices: An Ethical Perspective

The use of subtherapeutic doses of antibiotics in food-producing animals has been linked to antibiotic resistant infections in humans. Although this practice has been banned in Europe, the U.S. regulatory authorities have been slow to act. This paper discusses the regulatory hurdles and ethical dilemmas of banning this practice within the context of the risk analysis model (risk assessment, risk management, and risk communication). Specific issues include unethical use of scientific uncertainty during the risk assessment phase, the rejection of the precautionary principle leading to ineffective risk management, and the criticality of risk communication to build consensus and force action. The underlying root cause is a conflict of values (Type I ethical problem) among key stakeholders, which is examined in depth along with an ethical analysis using public health ethical values.     

Modelling the dynamic air-water-sediment coupled fluxes and occurrence of polychlorinated biphenyls in a high altitude lake

The BIODEP model in terms of atmosphere-lake interactions was developed. The model was applied to an oligotrophic, dimictic high altitude lake (Lake Redo, Pyrenees) for a range of polychlorinated biphenyl (PCB) congeners. High altitude lakes, which receive their contaminant inputs uniquely from the atmosphere through long-range atmospheric transport, provide ideal controlled environments for the study of the interactions between atmospheric depositional and water column biogeochemical processes. The BIODEP model was able to predict dissolved water concentrations and PCB accumulation in the lake sediment within a factor of 2. This shows that the BIODEP model captures the essential processes driving the sink of POPs in high altitude lakes and that POP occurrence in the lake is driven by direct atmospheric inputs with limited influence from the watershed. An important seasonal variability in water column concentrations is predicted which should have important implications in sampling strategies. Furthermore, it is shown that diffusive air-water exchange dominated the PCB dynamics in the lake, especially for the less chlorinated biphenyls.     

Occurrence and degradation of butyltins and wastewater marker compounds in sediments from Barcelona harbor, Spain

Contamination of Barcelona harbor sediments was assessed by the quantitative determination of butyltins (TBT, DBT and MBT) and surfactant intermediates, namely linear alkylbenzenes (LABs) and nonylphenols (NPs), as markers of urban and industrial wastewater contamination, respectively. Degradation indexes of TBT and LABs were calculated. Tributyltin predominated in the whole area over its degradation products, ranging from 98 to 4702 ng Sn/g. These elevated concentrations reveal a persistent historical contamination and a moderate degradation (BT(deg)). Moreover, the high LAB concentrations (1.2-53.1 microg/g) compared to the relatively low NP levels (3.8-72.0 ng/g) suggest a predominance of urban over industrial wastewater inputs, although a significant correlation (r(2) = 0.82, N = 12, P = 0.001) between LABs and NPs was found. Stormwater runoff and combined sewer overflows (CSO) were likely the most possible sources for both surfactant intermediates. The high degradation index values obtained for LABs could indicate an improvement in the wastewater management reducing its recent discharge into the Barcelona harbor area.     

Multimedia Integrated Modeling for Environmental Protection: Introduction to a Collaborative Framework

The EPA's Office of Research and Development is embarking on a long term project to develop a Multimedia Integrated Modeling System (MIMS). The system will have capabilities to represent the transport and fate of nutrients and chemical stressors over multiple spatial and temporal scales. MIMS will be designed to improve the environmental management community's ability to evaluate the impact of air and water quality and watershed management practices on stream and estuarine conditions. The system will provide a computer-based problem-solving environment for testing understanding of multimedia (atmosphere, land, water) environmental problems, such as the movement of chemicals through the hydrologic cycle, and the response of aquatic ecological systems to land-use change, with initial emphasis on the fish health endpoint. The design will attempt to combine the state-of-the-art in computer science, system design, and numerical analysis (i.e., object-oriented design, parallel processing, advanced numerical libraries including analytic elements) with the latest advancements in process level science (hydrology, atmospheric sciences, chemistry, ecology). The purpose of this paper is to introduce a vision for a MIMS and anticipate the challenges to its development.