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Sokolowski A Fichet D Garcia-Meunier P Radenac G Wolowicz M Blanchard G 《Chemosphere》2002,47(5):475-484
Soft tissue accumulated concentrations of nine metals (V, As, Se, Ag, Cd, Pb, Mn, Cu and Zn) were studied in two main phenotypes (1) according to external shell colour (white and pink), and (2) according to shell shape (shell with a rounded posterior end--"regular" and with an elongate posterior end and a notable flexure--"irregular") of the Baltic clam Macoma balthica from southern Baltic Sea off Poland. No differences in metal concentrations were observed between colour-based phenotypes. By contrast, "irregular" clams exhibited generally higher concentrations of all elements in their tissues than "regular" bivalves. This finding provides the first reference on a potential linkage of shell deformation with tissue metal concentrations within one entire population of clams living in the same habitat. Different ability of metal handling in the shape-based phenotypes is presumably related to different physiological capacity of the bivalves induced by the selection effect of specific environmental conditions. It is suggested that unfavourable conditions in deep waters of the Gulf of Gdansk (e.g. hypoxia/anoxia, hydrogen sulphide, elevated bioavailability of metals) induces, in a certain part of the population, morphological deformation of shell (thereby leading to irregular shape) and in parallel physiological adaptations which result in greater sensitivity to trace metals of "irregular" clams. This hypothesis however, requires further investigation with special focus on genetic divergences between phenotypes because till now we cannot exclude the co-occurrence of two types (semi-species) of clams in the Gulf: an Atlantic type and a Baltic type. Genetic analysis with a use of DALP technique revealed strong intrapopulational polymorphism but no fingerprints or intraspecific polymorphism characterising any of the phenotypes considered (both colour- and shape-based). Since eight polymorphic loci were clearly identified further studies of population genetic structure hold optimistic promise. 相似文献
125.
Matrix diffusion in saturated rocks with very low permeability is one of the major mechanisms of solute transport. Laboratory out-diffusion experiments on rock samples may provide an estimate of the bulk diffusion coefficient. However, numerous results have shown that this average parameter does not really depict the complex mechanism of diffusion as a function of the internal heterogeneity of crystalline rocks. Two-dimensional images of the porosity distribution in a granite sample were obtained by impregnation with a radioactive resin and autoradiography. Some examples based on these images and synthetic images were used to perform numerical simulations of out-diffusion using two different random walk methods. The simulated shapes of the out-diffusion curves depend on the spatial distribution of the porosity and on the pore connectivity with the border of the sample. Such relations might explain the multiple nested slopes or the convex shapes often observed on real experimental curves. 相似文献
126.
Dissolved organic matter in pore water of freshwater sediments: effects of separation procedure on quantity, quality and functionality 总被引:2,自引:0,他引:2
Pore water was separated either with or without water extraction prior to centrifugation (7600 or 20 000 × g) in order to investigate the effects of separation procedure on the amount and properties of dissolved organic matter (DOM i.e. the material passing through a 0.45-μm filter) in three freshwater sediments. On the basis of solubility in alkaline, organic matter was concluded to compose of humic substances in two (S1 and S3) and of humin (S2) in one of the sediments. DOM in the samples was quantified by total organic carbon measurement. Specific UV-absorption (SUVA) and high performance size exclusion chromatography (HPSEC) analyses were used to characterize DOM. Sorption of pyrene was used as a measure for functionality of DOM. Both water extraction and centrifugation speed were shown to affect the properties of DOM; however, the effects were sediment dependent. Water extraction increased the amount of DOM separated from the two sediments that had humic character (S1 and S3). In most cases water extraction increased SUVA and shifted the molecular size distribution of DOM towards larger sizes. The separation procedure had also an effect on the functionality of DOM. In water extracted samples of S2 and S3 the sorption of pyrene was higher than in the corresponding samples separated without water extraction, whereas in S1 similar effect was not found. Generally, centrifugation speed had smaller effects on the properties of DOM than water extraction. The fact that the effects of separation procedure on DOM depend on the sediment characteristics complicates the comparison between samples and evaluation of functionality in field conditions. 相似文献
127.
Anita Aisenberg Carmen Viera Fernando G. Costa 《Behavioral ecology and sociobiology》2007,62(1):29-35
Sexual selection theory predicts that a higher investment in offspring will turn females into the selective sex, while males
will compete for accessing and courting them. However, there are exceptions to the rule. When males present a high reproductive
investment, sex roles can reverse from typical patterns, turning males into the choosy sex, while females locate males and
initiate courtship. In many spiders, males are smaller than females, wandering in search of sedentary females and maximizing
the number of copulations. In the present study, we present findings on the sand-dwelling wolf spider, Allocosa brasiliensis, evidencing a reversal in typical courtship roles reported for the first time in spiders. Males were bigger than females.
Females located males and initiated courtship. Copulation always occurred in male burrows and took place mainly in long burrows.
Males donated their burrows to the females after copulation, closing the entrance before leaving with female cooperation from
inside. Males would provide females with a secure place for ovipositing, being exposed to predation and diminishing their
future mating possibilities until constructing a new burrow. The cost of vacating the burrow and losing the refuge in an unpredictable
habitat, such as sand dunes, would explain the courtship roles reversal in this spider species. Results turn A. brasiliensis as a promising model for discussing the determinants of sex roles and the pressures that drive their evolution and maintenance.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. 相似文献
128.
Herzke D Gabrielsen GW Evenset A Burkow IC 《Environmental pollution (Barking, Essex : 1987)》2003,121(2):293-300
The levels of polychlorinated camphenes (toxaphenes) were investigated in liver samples from 18 glaucous gulls (Larus hyperboreus) from Bj?rn?ya (74 degrees N, 19 degrees E) and four individuals from Longyearbyen (78 degrees N, 15 degrees E). Additionally brominated flame retardants (BFRs), PCBs and chlorinated pesticides were investigated in liver and intestinal contents of 15 of the glaucous gulls from Bj?rn?ya. Of the analysed BFRs only 2,2',4,4'-tetra- and 2,2',4,4',5-pentabrominated diphenylethers (PBDE 47 and 99) could be detected. The concentrations ranged between 2 and 25 ng/g ww. In addition, high resolution measurements with GC/HRMS revealed the existence of several, not quantified, PBDEs and polybrominated biphenyls (PBBs) congeners in the samples. B9-1679 and B8-1413 were the dominating toxaphenes with median concentrations of 8 and 15 ng/g ww. Concentrations of toxaphenes and PBDEs were up to 100-times lower than the concentrations of PCB and some of the pesticides. PCB and p,p/-DDE constituted 90% of the contaminants found. 相似文献
129.
Provisional physical habitat indices were developed and validatedfor Maryland Coastal and Non-Coastal Plain streams using variables (commonly called metrics) that best discriminated reference and degraded conditions based on biological, chemicaland land use data from the 1994–97 Maryland Biological Stream Survey (MBSS). These habitat indices contained variables that described structural, hydrological, vegetative and aesthetic components of stream habitat. Variables with the best discriminatory power for Coastal Plain streams were: instream habitat, velocity/depth diversity, pool/glide/eddy quality, embeddedness, maximum depth and aesthetic rating. Physical habitat variables with the best discriminatory power for Non-Coastal Plain sites were: instream habitat, velocity/depth diversity, riffle/run quality, embeddedness, number of rootwads and aesthetic rating. The overall classification efficiency forindex validation was 76% for both indices pooled over both strata. Scaled physical habitat index values (0–100) for bothstrata identified nearly twice as many good sites (31%) as very poor sites (16%). More than half the Maryland sites werein the poor to fair range (53%). 相似文献
130.
Christopher S. Jones Caroline A. Davis Chad W. Drake Keith E. Schilling Samuel H.P. Debionne Daniel W. Gilles Ibrahim Demir Larry J. Weber 《Journal of the American Water Resources Association》2018,54(2):471-486
Various techniques exist to estimate stream nitrate loads when measured concentration data are sparse. The inherent uncertainty associated with load estimation, however, makes tracking progress toward water quality goals more difficult. We used high‐frequency, in situ nitrate sensors strategically deployed across the agricultural state of Iowa to evaluate 2016 stream concentrations at 60 sites and loads at 35 sites. The generated data, collected at an average of 225 days per site, show daily average nitrate‐N yields ranging from 12 to 198 g/ha, with annual yields as high as 53 kg/ha from the intensely drained Des Moines Lobe. Thirteen of the sites that capture water from 82.5% of Iowa's area show statewide nitrate‐N loading in 2016 totaled 477 million kg, or 41% of the load delivered to the Mississippi–Atchafalaya River Basin (MARB). Considering the substantial private and public investment being made to reduce nitrate loading in many states within the MARB, networks of continuous, in situ measurement devices as described here can inform efforts to track year‐to‐year changes in nitrate load related to weather and conservation implementation. Nitrate and other data from the sensor network described in this study are made publicly available in real time through the Iowa Water Quality Information System. 相似文献