Newly metamorphosed <Emphasis Type="Italic">Elysia clarki</Emphasis> juveniles feed on and sequester chloroplasts from algal species different from those utilized by adult slugs

The adult, sacoglossan sea slug, Elysia clarki (Pierce et al. in Molluscan Res 26, 2006), sequesters functional chloroplasts in cells of the digestive diverticula from four species of macroalgae in the order Bryopsidales (Penicillus capitatus, Penicillus lamourouxii, Halimeda incrassata, and Halimeda monile). Feeding experiments were conducted in December, 2003, using individuals raised in the laboratory from egg masses laid by E. clarki adults which had been collected from Grassy Key, Florida, USA, and 29 species of macroalgae collected from the Florida Keys, Tampa Bay, Tarpon Springs, Florida, or Woods Hole, Massachusetts or obtained from the Culture Collection of Algae at the University of Texas at Austin, Texas. For the first 14-day post-metamorphosis, juveniles ate only the thin filamentous species, Bryopsis plumosa or Derbesia tenuissima. Transmission electron microscopy showed that the chloroplasts from both algae were sequestered intracellularly in juvenile slugs. Individuals offered any other macroalga, including the four species fed on by adults, did not feed on or incorporate any chloroplasts, and soon died. Juveniles switched from B. plumosa to P. capitatus at a length of ∼ 1.0 cm, and fixed for microscopy 14 days later had intact intracellular chloroplasts from both algae. Nucleotide sequences of the chloroplast gene, rbcL, from DNA extracted from E. clarki, collected from Vaca Key, Florida, were aligned with 22 other available macroalgal rbcL sequences indicating that these E. clarki adults had fed on three species of algae in the Bryopsidales including Bryopsis pennata, and TEM results partially confirmed this conclusion.     

Using the expert model PERPEST to translate measured and predicted pesticide exposure data into ecological risks

An important topic in the registration of pesticides and the interpretation of monitoring data is the estimation of the consequences of a certain concentration of a pesticide for the ecology of aquatic ecosystems. Solving these problems requires predictions of the expected response of the ecosystem to chemical stress. Up until now, a dominant approach to come up with such a prediction is the use of simulation models or safety factors. The disadvantage of the use of safety factors is a crude method that does not provide any insight into the concentration–response relationships at the ecosystem level. On the other hand, simulation models also have serious drawbacks like that they are often very complex, lack transparency, their implementation is expensive and there may be a compilation of errors, due to uncertainties in parameters and processes. In this paper, we present the expert model prediction of the ecological risks of pesticides (PERPEST) that overcomes these problems. It predicts the effects of a given concentration of a pesticide based on the outcome of already performed experiments using experimental ecosystems. This has the great advantage that the outcome is more realistic. The paper especially discusses how this model can be used to translate measured and predicted concentrations of pesticides into ecological risks, by taking data on measured and predicted concentrations of atrazine as an example. It is argued that this model can be of great use to evaluate the outcome of chemical monitoring programmes (e.g. performed in the light of the Water Framework Directive) and can even be used to evaluate the effects of mixtures.     

Aquatic fate assessment of the polycyclic musk fragrance HHCB. Scenario and variability analysis in accordance with the EU risk assessment guidelines

By means of the environmental fate and distribution models laid down in the Technical Guidance Documents (TGD) and implemented in the European Union System for the Evaluation of Substances (EUSES) environmental concentrations of the polycyclic musk fragrance HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta-[g]-2- benzopyrane; trade name: e.g. Galaxolide) were calculated for the aquatic environment under consideration of various scenarios. The results were then compared to monitoring data from the region of North Rhine-Westphalia (River Ruhr). An uncertainty analysis was carried out to determine sensitive parameters, to integrate environmental variability and to confirm the model's calculations. The standard scenario of EUSES overestimates the measured concentrations, which confirms the conservative nature of the calculations. The regional-specific scenarios lead to lower deviations from the measured values than the standard scenario. Deviations range from one to two orders of magnitude in the effluent of sewage treatment plants; they amount to one order of magnitude for surface water concentrations on a local scale and conform to monitoring data on a regional scale. The use of measured bioconcentration factors for fish instead of estimated ones reduces deviations remarkably. The investigation reveals that unrealistic worst-case calculations of HHCB can at best be ameliorated by the application of more realistic emission rates and measured bioconcentration factors. The use of regional-specific parameters also diminishes the deviations of the calculations from the measured concentrations.     

Inter- and intra-species variation in acute zinc tolerance of field-collected cladoceran populations

Acute zinc toxicity was assessed for 10 freshwater cladoceran species collected in six different ecosystems across Europe and for two standard laboratory-reared species (Daphnia magna and Ceriodaphnia dubia). The collected organisms belonged to five different genera: Daphnia (subgenus Daphnia and Ctenodaphnia), Ceriodaphnia, Simocephalus, Acroperus and Chydorus. The 48-h EC50 of the field-collected organisms tested in standard laboratory water ranged from 375+/-141 to 4314+/-1513 microg Znl(-1). The laboratory clone of D. magna was less sensitive than the majority of the field-collected species, while our laboratory Ceriodaphnia dubia was the second most sensitive. Considerable inter-species variation was found within the genus of Ceriodaphnia (factor 6) and within the genus Daphnia (factor 8). Among the different (sub)genera tested, Chydorus and Ctenodaphnia were significantly more tolerant than the others (up to a factor 3 difference). A significant positive relationship (r2=0.67, p<0.05) between the mean cladoceran 48-h EC50 and the ambient zinc concentration of the different aquatic systems was demonstrated, suggesting a role of acclimation and/or adaptation. No significant correlation between the acute zinc tolerance and the length of the organisms was found.     

Synthesis of Harvard Environmental Protection Agency (EPA) Center studies on traffic-related particulate pollution and cardiovascular outcomes in the Greater Boston Area

The association between particulate pollution and cardiovascular morbidity and mortality is well established. While the cardiovascular effects of nationally regulated criteria pollutants (e.g., fine particulate matter [PM_2.5] and nitrogen dioxide) have been well documented, there are fewer studies on particulate pollutants that are more specific for traffic, such as black carbon (BC) and particle number (PN). In this paper, we synthesized studies conducted in the Greater Boston Area on cardiovascular health effects of traffic exposure, specifically defined by BC or PN exposure or proximity to major roadways. Large cohort studies demonstrate that exposure to traffic-related particles adversely affect cardiac autonomic function, increase systemic cytokine-mediated inflammation and pro-thrombotic activity, and elevate the risk of hypertension and ischemic stroke. Key patterns emerged when directly comparing studies with overlapping exposure metrics and population cohorts. Most notably, cardiovascular risk estimates of PN and BC exposures were larger in magnitude or more often statistically significant compared to those of PM_2.5 exposures. Across multiple exposure metrics (e.g., short-term vs. long-term; observed vs. modeled) and different population cohorts (e.g., elderly, individuals with co-morbidities, young healthy individuals), there is compelling evidence that BC and PN represent traffic-related particles that are especially harmful to cardiovascular health. Further research is needed to validate these findings in other geographic locations, characterize exposure errors associated with using monitored and modeled traffic pollutant levels, and elucidate pathophysiological mechanisms underlying the cardiovascular effects of traffic-related particulate pollutants.

Implications: Traffic emissions are an important source of particles harmful to cardiovascular health. Traffic-related particles, specifically BC and PN, adversely affect cardiac autonomic function, increase systemic inflammation and thrombotic activity, elevate BP, and increase the risk of ischemic stroke. There is evidence that BC and PN are associated with greater cardiovascular risk compared to PM_2.5. Further research is needed to elucidate other health effects of traffic-related particles and assess the feasibility of regulating BC and PN or their regional and local sources.     

UV Fourier transform measurements of tropospheric O3, NO2, SO2, benzene, and toluene.

Using the differential optical absorption spectroscopy (DOAS) technique and a Fourier transform spectrometer, NO2, SO2, O3, benzene. and toluene were measured during three measurement campaigns held in Brussels in 1995, 1996, and 1997. The O3 concentrations could be explained as the results of the local photochemistry and the dynamical properties of the mixing layer. NO2 concentrations were anti-correlated to the O3 concentrations, as expected. SO2 also showed a pronounced dependence on car traffic. Average benzene and toluene concentrations were, respectively 1.7 ppb and between 4.4 and 6.6 pbb, but high values of toluene up to 98.8 ppb were observed. SO2 concentrations and to a lesser extent, those of NO2 and 03, were dependent on the wind direction. Ozone in Brussels has been found to be influenced by the meteorological conditions prevailing in central Europe. Comparisons with other measurements have shown that 03 and SO2 data are in general in good agreement, but our NO2 concentrations seem to be generally higher.     

Reproduction study of toxaphene in the rat

The purpose of the present study was to investigate in rats the reproductive effects of toxaphene, an insecticidal mixture which has been identified as a pollutant in the Great Lakes ecosystem. Groups of 30 female and 15 male weanling rats were given toxaphene in the diets at 0, 4.0, 20, 100 or 500 ppm in a 1 generation 2 litter reproduction study. Toxaphene treatment at the levels studied had no effects on the litter size, pup weight, fertility, or gestation and survival indices. Toxic effects in the parental rats included depressed weight gain, elevated serum cholesterol, and increased liver and kidney weight and hepatic microsomal enzyme activities. Most of these effects were associated only with 500 ppm toxaphene treatment. Treatment-related histological changes in the liver, thyroid and kidney of adult rats were observed at levels as low as 20 ppm. Based on the data presented, the no observable adverse effect dose of toxaphene was considered to be 4.0 ppm in the diet (0.29-0.38 mg/kg b.w./day depending on the amount of dietary intake).     

Copper regulation and homeostasis of Daphnia magna and Pseudokirchneriella subcapitata: influence of acclimation

This study aimed to evaluate (1) the capacity of the green alga Pseudokirchneriella subcapitata and the waterflea Daphnia magna to regulate copper when exposed to environmentally realistic copper concentrations and (2) the influence of multi-generation acclimation to these copper concentrations on copper bioaccumulation and homeostasis. Based on bioconcentration factors, active copper regulation was observed in algae up to 5 microg Cu L(-1) and in daphnids up to 35 mug Cu L(-1). Constant body copper concentrations (13+/-4 microg Cu g DW(-1)) were observed in algae exposed to 1 through 5 microg Cu L(-1) and in daphnids exposed to 1 through 12 microg Cu L(-1). At higher exposure concentrations, there was an increase in internal body copper concentration, while no increase was observed in bioconcentration factors, suggesting the presence of a storage mechanism. At copper concentrations of 100 microg Cu L(-1) (P. subcapitata) and 150 microg Cu L(-1) (D. magna), the significant increases observed in body copper concentrations and in bioconcentration factors may be related to a failure of this regulation mechanism. For both organisms, internal body copper concentrations lower than 13 microg Cu g DW(-1) may result in copper deficiency. For P. subcapitata acclimated to 0.5 and 100 microg Cu L(-1), body copper concentrations ranged (mean+/-standard deviation) between 5+/-2 microg Cu g DW(-1) and 1300+/-197 microg Cu g DW(-1), respectively. For D. magna, this value ranged between 9+/-2 microg Cu g DW(-1) and 175+/-17 microg Cu g DW(-1) for daphnids acclimated to 0.5 and 150 microg Cu L(-1). Multi-generation acclimation to copper concentrations >or =12 microg Cu L(-1) resulted in a decrease (up to 40%) in body copper concentrations for both organisms compared to the body copper concentration of the first generation. It can be concluded that there is an indication that P. subcapitata and D. magna can regulate their whole body copper concentration to maintain copper homeostasis within their optimal copper range and acclimation enhances these mechanisms.     

Some political aspects of pollution control

In this paper some principles of optimal control theory are applied to an examination of the possible differences that political and economic decisions making may have in the area of pollution control. The main points are that (1) Pollution Control Boards (PCB's) may behave as though they place weights on control and benefit functions that differ from market determined weights, (2) divergencies between political and market weights impose welfar; losses, and (3) given that PCB's may be succeeded by another board the current PCB may adapt its behavior to counteract or enforce the expected future behavior of the new PCB.