Plasma nonesterified fatty acids of marine teleost and elasmobranch fishes

The plasma nonesterified fatty acids (NEFA) of five species of temperate zone marine teleost fishes (Northwestern Atlantic), one Arctic marine teleost (Eastern Canadian Arctic), and four species of marine elasmobranchs (Northwestern Atlantic) are reported. Four fatty acids, 16:0, 18:1n9, 20:5n3 and 22:6n3, comprised 70 to 83% of total NEFA in the plasma of all temperate teleost species examined. With the sole exception of 18:1, these differed from the predominant fatty acids, 14:1, 16:1, 18:1 and 20:5n3, in the Arctic species. The predominant fatty acids in elasmobranch NEFA were 16:0, 22:6n3 and 18:1n9 in all species but saturated fatty acids (14:0, 16:0 and 18:0) accounted for 40% of all NEFA in all elasmobranchs examined. Monoenes represented a greater, and polyenes a smaller, percentage of the fatty acids in the Arctic sculpin compared to the temperate sculpin. Fatty acids of the n3 series were lower in the plasma of the Arctic sculpin compared to the temperate sculpin. Comparisons with published values for freshwater fish using the same method indicate the n3:n6 ratio is higher in the marine teleost fishes. Ratios of n3:n6 fatty acids ranged from 1.80 to 7.94 for the elasmobranchs and were on average lower than those for the marine teleosts. Total levels of NEFA for the elasmobranchs were between 193 and 399 nmol ml^-1, lower than the values reported here for teleosts but within the range reported by others for some teleost fishes.     

Anthropogenic subsidies alter stream consumer-resource stoichiometry, biodiversity, and food chains.

Urbanization is dramatically changing nutrient and organic matter regimes in streams, yet the community and ecosystem implications often remain obscure. We assessed the consequences of sewage-derived particulate organic matter (SDPOM) for invertebrate community structure and function in a headwater stream. Using stable isotope analyses, we found assimilation of organic SDPOM to double community secondary production, and stoichiometric analyses revealed SDPOM enriched in phosphorus (P) to foster putatively fast-growing, P-rich consumers in the subsidized reach. This altered consumer-resource stoichiometry impacted both community structure and nutrient fluxes through the invertebrate community. Community structure shifted toward significantly reduced diversity and evenness in the subsidized reach and consequently toward shorter food chains. Our integration of ecological stoichiometry with stable isotope analyses and food web ecology expands the previous focus of traditional ecotoxicology and ecophysiology to an ecosystem-level appreciation of pollutant ecology.     

Sources of pesticides in surface waters in Switzerland: pesticide load through waste water treatment plants--current situation and reduction potential

Concentrations of pesticides in Swiss rivers and lakes frequently exceed the Swiss quality goal of 0.1 microg/l for surface waters. In this study, concentrations of various pesticides (e.g., atrazine, diuron, mecoprop) were continuously measured in the effluents of waste water treatment plants and in two rivers during a period of four months. These measurements revealed that in the catchment of Lake Greifensee, farmers who did not perfectly comply with 'good agricultural practice' caused at least 14% of the measured agricultural herbicide load into surface waters. Pesticides, used for additional purposes in urban areas (i.e. protection of materials, conservation, etc.), entered surface waters up to 75% through waste water treatment plants.     

Immediate and unexplained fetal death during mid-trimester amniocentesis

Immediate and unexplained fetal death during mid-trimester amniocentesis for prenatal diagnosis was found to be an uncommon though real phenomenon. A survey of programmes in the United States detected 5 cases from 7524 at 4 centres. Postmortem examination was not helpful and a neurogenic mechanism is postulated. Awareness of this phenomenon and routine pre- and post-amniocentesis ultrasound monitoring may clarify the actual prevalence and etiology.     

Restoring Ecological Integrity in Highly Regulated Rivers: The Role of Baseline Data and Analytical References

The goal of restoring ecological integrity in rivers is frequently accompanied by an assumption that a comparative reference reach can be identified to represent minimally impaired conditions. However, in many regulated rivers, no credible historical, morphological or process-based reference reach exists. Resilient restoration designs should instead be framed around naturalization, using multiple analytical references derived from empirically-calibrated field- and model-based techniques to develop an integrated ecological reference condition. This requires baseline data which are rarely collected despite increasing evidence for systematic deficiencies in restoration practice. We illustrate the utility of baseline data collection in restoration planning for the highly fragmented and regulated lower Merced River, California, USA. The restoration design was developed using various baseline data surveys, monitoring, and modeling within an adaptive management framework. Baseline data assisted in transforming conceptual models of ecosystem function into specific restoration challenges, defining analytical references of the expected relationships among ecological parameters required for restoration, and specifying performance criteria for post-project monitoring and evaluation. In this way the study is an example of process-based morphological restoration designed to prompt recovery of ecosystem processes and resilience. For the Merced River, we illustrate that project-specific baseline data collection is a necessary precursor in developing performance-based restoration designs and addressing scale-related uncertainties, such as whether periodic gravel augmentation will sustain bed recovery and whether piecemeal efforts will improve ecological integrity. Given the numerous impediments to full, historical, restoration in many river systems, it seems apparent that projects of naturalization are a critical step in reducing the deleterious impacts of fragmented rivers worldwide.