Genotype-specific growth of hard clams (genus Mercenaria) in a hybrid zone: variation among habitats

Shell growth rate is an important component of fitness in bivalve molluscs. Using the parameter computed from the von Bertalanffy growth equation, we quantitatively compared rates of annual shell grwoth among the hard clams Mercenaria mercenaria, M. campechiensis, and their hybrids sampled from a variety of habitats in the Indian River lagoon, Florida, USA, a zone of species overlap and natural hybridization. Our results indicate that the classical paradigm describing hard clam growth, in which growth rate is fastest in M. campechiensis, intermediate in hybrids, and slowest in M. mercenaria is not supported in the Indian River lagoon. Instead, M. campechiensis has a growth advantage in deep-water habitats in the northern section of our study area. In the central and southern sections of our study area, hybrids have a growth advantage over M. mercenaria in shallow-water habitats, but M. mercenaria has a growth advantage over hybrids in deep-water habitats. In all other sampled habitats, either growth rate among genotype classes is equal, or M. mercenaria has a growth advantage. This complex relationship between genotype and habitat-specific growth provides a mechanism for selection to act on hard clams in the Indian River.     

Development of new dunes in the Dutch Delta: nature compensation and ‘building with nature’

A new dune area was constructed by beach and foreshore nourishments along the Delfland Coast in the southwestern Netherlands. The new area is intended to be a compensation for losses of existing high quality dunes in nearby areas, due to the use/construction of Maasvlakte 2, the new harbour extension of Rotterdam opening in 2013. The target habitats for compensation include dry grey dunes and moist dune valley grassland. Due to the habitat type, the nourished material had to have a special character. The nourishment was carried out according to a special design and initial development of the new area had to follow certain pathways. In order to meet the compensation requirements in time. Careful monitoring is done to assess whether development of the new habitat is taking place in the direction of the desired target habitats. This paper reports on the construction of the new area and on the first years of development and monitoring. The monitoring mainly concerns development of the abiotic landscape elements, geomorphology, groundwater and soils. The lessons learned from this area are discussed in the light of the development of other recent young nature areas in the sandy Dutch delta coast. This gives new insights for coastal management in general in the context of building with nature.     

The synthetic pyrethroid isomers II. Biological activity

Abstract

Pure optical isomers of phenothrin, permethin and cypermethrin were synthesised and tested on a wide spectrum of insects (Blattella germanica, Leptinotarsa decemlineata, Tribolium confusum, Oncopeltus fasciatus, Musca domestica, Aedes aegypti). Our results suggest that in the structurally related series phenothrin, permethrin and cypermethrin the chemical modifications had only a small influence on intrinsic activity of the compounds at the target site. The activity of piperonylbutoxide synergised 1Rtrans phenothrin and 1Rcis permethrin (LD₅₀=1.2 ng/fly in both cases) is in a similar range to the most active 1RcisS cypermethrin isomer alone or with PB (LD₅₀=0.9 and 0.4 ng/fly, respectively). Some cypermethrin isomers considered previously to be totally inactive show significant activity depending on the tested insect species. The 1ReisR and 1RtransR isomers proved to be as active as the most potent isomers on mosquito. A similarly unexpected result was that in the case of mosquito all four trans isomers were significantly more active than the corresponding eis isomers.

The superiority of the (S)‐α configuration over (R)‐α was found. It does not result from a higher intrinsic activity at the target site, but rather from the enhanced metabolic resistance of (S)‐α‐esters to ester cleavage as confirmed by Synergist studies. The activity of the two most potent stereoisomers, 1ReisS and 1RtransS, could not be elevated by quinalphos, while the inactive 1ScisR and 1StransR isomers showed significant activity with the esterase inhibitor quinalphos administered sublethally.

In contrast with the antagonism between (S)‐ and (R)‐α‐epimers of cypermethrin reported earlier a considerable synergism was observed between 1RtransS and 1StransR enantiomer pair on flour beetle and housefly in tarsal contact tests.

The results with stereoisomers and their mixtures were utilised in the development of two new products, Chinmix (beta‐cypermetrhin) and Transmix (theta‐cypermetrhin).     

Novel evidence for natural formation of dioxins in ball clay

Elevated concentrations of dioxins in ancient ball clay from the Mississippi Embayment suggest natural formation of dioxins in the environment. Evidence for such natural formation in ball clay derives from unique congener profiles in undisturbed ancient clay deposits and from the lack of other anthropogenic contaminants. Here we present novel evidence of natural formation of dioxins based on congener-specific carbon isotopic analysis of octachlorodibenzo-p-dioxin (OCDD) in ball clays from the USA and Japan. The analyses were performed using a combination of double-column high performance liquid chromatography clean-up and two-dimensional gas chromatography-isotope ratio mass spectrometry. Elevated concentrations of OCDD found in ball clays from the USA and Japan were isotopically distinguished from the anthropogenic source materials (fly ash and pentachlorophenol) and environmental samples (sediment and soil). The isotopic signatures and the occurrence of OCDD in ancient ball clays deposited in the Tertiary Era provide evidence for the in situ formation of dioxins.     

Potentially Allergenic Airborne Particles in the Vicinity of a Yeast and Penicillin Production Plant

Potential health risks of exposure to emissions of a yeast and penicillin production plant were investigated by measuring viable particles and protein contents of particles in ambient air. The results showed a clear decrease of the downwind number of yeast colonyforming units with increasing distance from the source. Upwind the number of yeast colony-forming units was zero. Identification showed that nearly all yeast were of the species Saccharomlces cerevisiae. Such a trend could not be found for the total number of colony-forming units (yeasts, molds, and bacteria) although the upwind concentration was slightly lower than the downwind concentration. The downwind protein concentration was significantly elevated compared to the upwind concentration.     

Daily Mortality and Air Pollution in the Netherlands

ABSTRACT

We studied the association of daily mortality with short-term variations in the ambient concentrations of major gaseous pollutants and PM in the Netherlands. The magnitude of the association in the four major urban areas was compared with that in the remainder of the country. Daily cause-specific mortality counts, air quality, temperature, relative humidity, and influenza data were obtained from 1986 to 1994. The relationship between daily mortality and air pollution was modeled using Poisson regression analysis. We adjusted for potential confounding due to long-term and seasonal trends, influenza epidemics, ambient temperature and relative humidity, day of the week, and holidays, using generalized additive models.

Influenza episodes were associated with increased mortality up to 3 weeks later. Daily mortality was significantly associated with the concentration of all air pollutants. An increase in the PM₁₀ concentration by 100 u.g/m³ was associated with a relative risk (RR) of 1.02 for total mortality. The largest RRs were found for pneumonia deaths. Ozone had the most consistent, independent association with mortality. Particulate air pollution (e.g., PM₁₀, black smoke [BS]) was not more consistently associated with mortality than were the gaseous pollutants SO₂ and NO₂. Aerosol SO₄ ^-2, NO₃ ^-, and BS were more consistently associated with total mortality than was PM₁₀. The RRs for all pollutants were substantially larger in the summer months than in the winter months. The RR of total mortality for PM₁₀ was 1.10 for the summer and 1.03 for the winter. There was no consistent difference between RRs in the four major urban areas and the more rural areas.     

Predicting applicants' job pursuit behavior from their selection expectations: the mediating role of the theory of planned behavior

Applicants' pretest expectations about the forthcoming selection procedure may serve as a key factor in applicants' decision‐making. The current study examined the validity of the theory of planned behavior (TPB) as an explanatory mechanism of the relationship between pretest selection expectations (warmth/respect, chance to demonstrate potential, difficulty of faking, unbiased assessment, feedback) and job pursuit behavior. Data were collected at two points in time, using a sample of applicants for the military. Selection expectations, job pursuit attitude, subjective norm, and controllability were significantly related to job pursuit intention. Job pursuit attitude mediated the relationship between selection expectations and job pursuit intention. Subjective norm and time lag were the only significant predictors of job pursuit behavior. Practical implications, strengths and limitations, as well as directions for further research are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Tissue-specific accumulation and lactational transfer of polychlorinated biphenyls, chlorinated pesticides, and brominated flame retardants in hooded seals (Cistophora cristata) from the Gulf of St. Lawrence: applications for monitoring

Accumulation and mother-pup transfer of halogenated organic contaminants was studied in hooded seal tissues from eastern Canada. Blubber polychlorinated biphenyl (PCB) and total pesticide concentrations were relatively high, possibly due to their high trophic level and demersal feeding habits. Blood plasma showed the lowest contaminant concentrations compared to blubber and liver, possibly due to a lower affinity of these compounds to lipoproteins in blood plasma. Total contaminant body burden correlated well with blubber, liver, and milk contaminants, but not with blood plasma contaminants, indicating that blood plasma might be less suitable to monitor contaminants in hooded seals. Lactational transfer favored less lipophilic contaminants and was associated with relatively high blood plasma PCB and polybrominated diphenyl ether concentrations in females. Despite lactational transfer, females did not show significantly lower blubber contaminant concentrations or burdens than males. This might be caused by their low blubber, and thus contaminant, loss during lactation compared to other species.     

Ah Receptor Agonists in UV-exposed Toluene Solutions of Decabromodiphenyl Ether (decaBDE) and in Soils Contaminated with Polybrominated Diphenyl Ethers (PBDEs) (9 pp)

Goal, Scope and Background The use of polybrominated diphenyl ethers (PBDEs) as flame retardants increases the risk for emissions of other brominated compounds, such as polybrominated dibenzodioxins (PBDDs) and dibenzofurans (PBDFs). The large homology in structure of PBDD/Fs and mechanism of toxic action, i.e. the capacity to activate the Ah receptor (AhR) pathway, compared to their well-studied chlorinated analogues, justifies a raised concern to study the environmental levels and fate of these compounds. Decabromodiphenyl ether (decaBDE) is the most widely used PBDE today. Studies on photolytic debromination of decaBDE in organic solvents have shown debromination of decaBDE, as well as formation of PBDFs. However, little is known about the transformation mechanisms and there are only scarce data on photoproducts and PBDE transformation in environmentally relevant matrices. In this study, mechanism-specific dioxin bioassays were used to study photolytic formation of AhR agonists in toluene solutions of decaBDE. In addition, the influence of irradiation time and UV-light wavelength on the formation was studied. PBDE congener patterns and presence of PBDD/Fs were analysed. Further, AhR agonists were analysed in agricultural soils contaminated with PBDEs. Soils were also exposed to UV-light to study changes in AhR agonist levels. Methods Toluene solutions of decaBDE were irradiated using three different spectra of UV-light, simulating UV-A (320-400 nm), UV-AB (280-400 nm), and UV-ABC (250-400 nm). Additionally, decaBDE solutions were exposed to narrow wavelength intervals (10 nm bandwidth) with the central wavelengths 280, 290, 300, 310, 320, 330, 340, 350, 360 nm. AhR agonists in decaBDE solutions were analysed with two different bioassays, the chick embryo liver-cell assay for dioxins (Celcad) and the dioxin responsive, chemically activated luciferase expression assay (DR-Calux). Also, the decaBDE solutions were analysed with LRGC-LRMS to obtain PBDE congener patterns for breakdown of decaBDE, and with HRGC-HRMS, for presence of PBDD/Fs. Four soils were exposed to UV-AB light, under both dry and moist conditions. Levels of AhR agonists in soil extract fractions, before and after UV-exposure, were analysed with the DR-Calux. Results and Discussion Significant levels of photoproducts able to activate the AhR pathway, up to 31 ng bio-TEQ/ml, were formed in UV-exposed decaBDE solutions. The transformation yield of decaBDE into AhR agonists was estimated to be at the 0.1%-level, on a molar basis. The net formation was highly dependent on wavelength, with the sample irradiated at 330 nm showing the highest level of dioxin-like activity. No activity was detected in controls. PBDE analysis confirmed decaBDE degradation and a clear time-dependent pattern for debromination of PBDE congeners. AhR agonist effect in the recalcitrant fractions of the soils corresponded to the levels of chemically derived TEQs, based only on chlorinated dioxin-like compounds in an earlier study. It was concluded that no significant levels of other AhR agonists, e.g. PBDFs, were accumulated in the soil. UV-light caused changes in AhR-mediated activity in the more polar and less persistent fractions of the soils, but it is not known which compounds are responsible for this. Recommendations and Perspective . The laboratory experiments in this study show that high levels of AhR agonists can be formed as photoproducts of decaBDE and it is important to elucidate if and under which conditions this might occur in nature. However, soil analysis indicates that photoproducts of PBDE do not contribute to the accumulated levels of persistent dioxin-like compounds in agricultural soil. Still, more data is needed to fully estimate the environmental importance of PBDE photolysis and occurrence of its photoproducts in other environmental compartments. Analysis with dioxin bioassays enabled us to gather information about photoproducts formed from decaBDE even though the exact identities of these compounds were not known. Conclusion Bioassays are valuable for studying environmental transformation processes like this, where chemical analysis and subsequent toxicological evaluation requires available standard compounds and information on toxicological potency. The use of bioassays allows a rapid evaluation of toxicological relevance.