Verteilungskoeffizienten chlorierter Kohlenwasserstoffe zwischen Muskulatur und Leber bei Fischen

Measured partition coefficients (KL_M/L) related to lipid-concentrations between the muscle (C_ML) and liver (C_LL) tissue of two fish species (Abramis brama, Zoarces viviparus) exhibit nominal values of unity according the relationship KL_M/L=C_ML/C_LL=1 for persistent compounds such as highly chlorinated PCB and values above one for degradable compounds for example chlorinated cyclohexanes or DDT. The corresponding theory is presented. The relationship holds for samples for single fish as well as for pooled samples.     

Mating expenditures reduced via female sex pheromone modulation in the primitively eusocial halictine bee, Lasioglossum (Evylaeus) malachurum (Hymenoptera: Halictidae)

The present paper reports on behavioral experiments and gas chromatographic analysis of chemical communication in the mating biology of the primitively eusocial sweat bee Lasioglossum (Evylaeus) malachurum. In a dual-choice experiment, a female made odorless was significantly less attractive than an untreated one. Attraction in L. (Evylaeus) malachurum is therefore mediated by a female-produced sex pheromone. Further bioassays showed that unmated gynes are more attractive to males than mated ones. Males are able to differentiate between the two groups of females as little as 3 h after mating. Biotests with different samples obtained from attractive gynes showed surface extracts to be most attractive. Behavioral tests with synthetic copies of the compounds identified as cuticular constituents of virgin gynes were highly attractive to males; the volatile bouquets consisting of n-alkanes, n-alkenes and iso- pentenyl esters of unsaturated fatty acids were the most attractive samples. Isopentenyl esters of unsaturated fatty acids were the key compounds in inducing male inspections as well as stimulating pounces and copulatory attempts. Virgin and nesting gynes differed clearly in the relative and absolute amounts of the volatiles on the cuticle. The total amount of volatiles was significantly higher in virgin gynes and decreased in breeding queens. Hydrocarbons were the dominant group of compounds in both groups of females. The relative amounts of the wax-type ester, hexadecyl oleate, iso- pentenyl esters, and a hitherto unidentified steroid were higher in attractive virgin gynes, while the relative proportions of hydrocarbons and lactones dominated in nesting queens. The site of sex pheromone production in attractive young L. (Evylaeus) malachurum gynes remains unknown. Head glands or Dufour's gland secretions may be involved. Another possible source of the `active principle' found among the cuticular lipids could be glandular cells of the epidermis. The significance of modulation of female sex pheromone composition is discussed in terms of a reduction in mating expenditures. Received: 30 April 1998 / Accepted after revision: 24 July 1998     

Completely disjunct mitochondrial DNA haplotype distribution without a phylogeographic break in a planktonic developing gastropod

Planktonic developing organisms are generally assumed to be good dispersers showing little genetic structuring in neutral markers. At first glance, this also applies to the planktonic developing periwinkle Tectarius striatus, an endemic gastropod from Macaronesia (i.e. Azores, Madeira, Canary Islands and Cape Verde Islands), where the only sign of genetic structuring hitherto is provided by a non-significant allozyme/RAPD heterogeneity between the Cape Verde Islands and the other archipelagos. However, partial sequences of the mitochondrial cytochrome b and cytochrome oxidase I genes now show that the Cape Verde Islands and the three other archipelagos have no haplotypes in common, whereas the latter three do share several haplotypes. Nevertheless, this highly disjunct haplotype distribution does not entail a phylogeographic break separating the haplotypes of both areas in two reciprocally monophyletic groups. This remarkable geographic and phylogenetic structuring may be explained by assuming that T. striatus colonized the Macaronesian archipelagos in periods when sea levels were lower (and/or volcanic activity was higher), so that seamounts peaked above sea level and could act as stepping-stones. Yet, after the last glacial period seamounts submerged, thus preventing further stepping-stones mediated dispersal of T. striatus between the Cape Verde Islands and the other archipelagos, while not affecting dispersal among the latter because of their closer proximity and connectivity. Hence, these contrasting patterns of neutral genetic variation in T. striatus show that genetic structuring in planktonic developing species may be far more complex than is usually assumed.     

Regional patterns of heavy metal exposure and contamination in the fish fauna of the Kharaa River basin (Mongolia)

Regional Environmental Change - Past and present gold mining operations scattered throughout the Kharaa River basin, Mongolia, have been identified as a major source of heavy metal and metalloid...     

Commercial phenoxyacetic herbicides control heavy metal uptake by wheat in a divergent way than pure active substances alone

Background

Impact of two widely used commercial herbicides, i.e. Aminopielik D 450 SL and Chwastox 300 SL, on the uptake and translocation of selected heavy metals in wheat plants Triticum aestivum L. cultivated in the laboratory pot experiments was investigated. Mineral-humus, loamy sand soil representative for the central part of Poland was applied. Bioavailable, exchangeable and total forms of Cd, Co, Cu, Zn, Pb, and Mn were determined. Transfer coefficients, translocation, and bioaccumulation factors illustrating metal migration in the plant were investigated.

Results

Administration of commercial herbicides significantly altered heavy metals uptake by wheat in a way distinctively different than that observed for the parent chemically pure synthetic auxins, i.e. 2,4-D and MCPA. In particular, Aminopielik D 450 SL and Chwastox 300 SL prompted heavy metals accumulation in roots as indicated by their high transfer coefficients. Further transport to above ground part of the plant was limited and element dependent.

Conclusions

This work clearly shows that commercial herbicide formulations may act in a distinctively different way than pure active ingredients alone.

     

Effects of Habitat Size and Patch Isolation on Reproductive Success of the Serpentine Morning Glory

Abstract: We examined the effects of habitat area and patch isolation on reproductive success in serpentine morning glory ( Calystegia collina [Convolvulaceae]), a primarily self-incompatible clonal plant endemic to serpentine outcrops in northern California's coast ranges. Within a 4000-km ² region, we compared the reproductive success of C. collina on 16 small (<5 ha) and 7 large ( >300 ha) outcrops. Flower and fruit production were significantly higher on large serpentine outcrops than on small outcrops. Fruit production also was positively correlated with the soil's ratio of calcium to magnesium. Successful pollination was positively affected by flower density and the number of other flowering patches within 100 m of a C. collina patch. The number of nearby flowering patches was considerably higher on large than on small outcrops. Flowers on large outcrops did not receive significantly more bee visitors than flowers on small outcrops, suggesting that pollination success is related to the quality rather than the quantity of pollen deposited. Fruit production by plants on both small and large outcrops was enhanced by the experimental addition of pollen from other patches, but not by the addition of pollen from the same patch. These findings demonstrate that the size of habitat may have strong effects on the reproductive success of locally endemic plants by enhancing opportunities for successful sexual reproduction. They also warn against the presumption that naturally patchy plant species are invulnerable to the effects of habitat fragmentation.     

Persistent toxic substances in soils and waters along an altitudinal gradient in the Laja River Basin, Central Southern Chile

In this study the levels and distribution of some persistent toxic substances (PTS) were investigated in soils, superficial water, and snow along an altitudinal gradient in the Laja River Basin (South Central Chile). The principal objective was to establish the basin's contamination status. The working hypothesis was that PTS levels and distribution in the basin are dependent on the degree of anthropogenic intervention. Fifteen PAHs, seven PCBs congeners, and three organochlorine pesticides were studied in superficial soil and water samples obtained along the altitudinal gradient and from a coastal reference station (Lleu-Lleu River). Soil samples were extracted using accelerated solvent extraction with acetone/cyclohexane (1:1) for PAHs and organochlorine compounds. Contaminants were extracted from water and snow samples by liquid-liquid extraction (LLE). PAH and organochlorine compound quantification was carried out by HPLC with fluorescence detection and GC-MS, respectively. PCBs in soils presented four different profiles in the altitudinal gradient, mainly determined by their chlorination degree; these profiles were not observed for the chlorinated pesticides. In general, the detected levels for the analyzed compounds were low for soils when compared with soil data from other remote areas of the world. Higher summation operator PAHs levels in soils were found in the station located at 227 masl (4243 ng g-1 TOC), in a forestry area and near a timber industry, where detected levels were up to eight times higher than the other sampling sites. In general, PAH levels and distribution seems to be dependent on local conditions. No pesticides were detected in surface waters. However, congeners of PCBs were detected in almost all sampling stations with the highest levels being found in Laja Lake waters, where 1.1 ng/l were observed. This concentration is two times higher than values reported for polluted lakes in the Northern Hemisphere. The presence of organochlorine compound in snow sampled at the highest elevation point of the basin is indicative of the transport and atmospheric deposition phenomena of alpha-HCH, gamma-HCH and PCB 52, with values being similar to the levels reported in Canadian snow samples. We conclude that environmental PTS substance levels are in general relatively low, although PAHs may be of concern in some areas of the basin.