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201.
From sexually mature female fish of 32 different species muscle tissues and eggs were collected at four sites in the Magdalena and Meta rivers in Colombia. In most of the fishes, organochlorine residues were found both in the muscle tissues and in the eggs. On a fat basis, the level of SDDT and PCBs in the muscle tissues ranged from 55–10 700 and 5–5610 ng/g lipid weight, respectively. The concentration of these compounds in the fish eggs were generally lower than those in the tissues. The levels of the residues in the fish were highest in the middle and lower part of the Magdalena River, indicating a contamination of the whole fish community. The results show that this river, especially its lower part after merging with the River Bogotá, is heavily influenced by anthropogenic persistent compounds. The pollution of lakes, dams, rivers and coastal areas with sewage, pesticides and industrial wastes is one of the most pressing environmental problems in Colombia. Since there are no statistics or other material that permit a diagnosis of the problem and its magnitude, it is urgent to carry out such investigations to identify sources and take appropriate measures. The responsibility for the use and control of industrial and agricultural chemicals is today shared among many regional corporations. We suggest the establishment of an authority at high technical and govermental level that can initiate monitoring and coordinate actions to alleviate the present situation. 相似文献
202.
Terje Laskemoen Tomas Albrecht Andrea Bonisoli-Alquati Jaroslav Cepak Florentino de Lope Ignacio G. Hermosell Lars Erik Johannessen Oddmund Kleven Alfonso Marzal Timothy A. Mousseau Anders P. Møller Raleigh J. Robertson Geir Rudolfsen Nicola Saino Yoni Vortman Jan T. Lifjeld 《Behavioral ecology and sociobiology》2013,67(2):301-309
Spermatozoa vary greatly in size and shape among species across the animal kingdom. Postcopulatory sexual selection is thought to be the major evolutionary force driving this diversity. In contrast, less is known about how sperm size varies among populations of the same species. Here, we investigate geographic variation in sperm size in barn swallows Hirundo rustica, a socially monogamous passerine with a wide Holarctic breeding distribution. We included samples from seven populations and three subspecies: five populations of ssp. rustica in Europe (Czech, Italy, Norway, Spain, and Ukraine), one population of ssp. transitiva in Israel, and one population of ssp. erythrogaster in Canada. All sperm traits (head length, midpiece length, tail length, and total length) varied significantly among populations. The variation among the European rustica populations was much lower than the differences among subspecies, indicating that sperm traits reflect phylogenetic distance. We also performed a test of the relationship between the coefficient of between-male variation in total sperm length and extrapair paternity levels across different populations within a species. Recent studies have found a strong negative relationship between sperm size variation and extrapair paternity among species. Here, we show a similar negative relationship among six barn swallow populations, which suggests that the variance in male sperm length in a population is shaped by the strength of stabilizing postcopulatory sexual selection. 相似文献
203.
J?rgen?I.?JohnssonEmail author Anders?Rydeborg L.?Fredrik?Sundstr?m 《Behavioral ecology and sociobiology》2004,56(4):388-392
In an experiment on territorial brown trout (Salmo trutta), we addressed the novel hypothesis that protective cover increases the value of a territory in relation to the perceived level of predation risk. We predicted that territory holders should invest more resources defending territories with cover than territories without cover, and that defence should increase as predation risk increases. First, trout were allowed to establish ownership in territories with or without overhead cover. Second, predation risk was manipulated by simulating aerial predator attacks in half of the territories of each type, whereupon the preference for cover was estimated. Third, owners of the four types of territories were staged in dyadic contests against size-matched intruders. Territory owners showed a preference for cover, which increased further after simulated predator attacks. In subsequent contests, conflicts over territories with cover were settled faster than conflicts over territories without cover, which may suggest that the value of cover increases the motivational asymmetry between owner and intruder. Consistent with our hypothesis, owners of territories with cover were much more aggressive if they had been subjected to predator attacks the day before the conflict. These results suggest that territory owners are able to estimate the value of protective cover in response to variation in the level of predation risk in the habitat.Communicated by J. Krause 相似文献
204.
Memory for the spatial layout of the everyday physical environment: Factors affecting rate of acquisition 总被引:1,自引:0,他引:1
Tommy Grling Anders Bk Erik Lindberg Tomas Nilsson 《Journal of environmental psychology》1981,1(4):263-277
That a memory representation of the spatial layout of a large-scale environment may be acquired very fast was shown in two experiments in which subjects (48 undergraduates and high-school students) were taken on tours through a residential area with which they were unfamiliar. Memory for the path traversed was almost perfect after the first trial, as indicated by almost perfect recall of the order in which a number of designated landmarks had been passed. Memory for the locations of the same landmarks appeared to reach an asymptotic level after the second of three trials. The memory representation of the locations were however not perfectly accurate, thus the asymptotic level might have been an acquisition plateau. The rate of acquisition was slightly faster for subjects driven in a car slowly through the area than for those who walked the same path. Men tended to improve slightly faster than women if they were driven by car but there were no other sex differences. Finally, the acquired memory representation appeared to be resistant to forgetting. Re-learning after a one-week retention interval was faster and rate of learning was not negatively affected whether the trials were massed or distributed with one week in between. The results are discussed in terms of hypotheses concerning the order in which different types of information about spatial layouts (landmarks, paths, and locations) are acquired. The bearing of the results on the question of why memory representations of the spatial layout are often found to be distorted is also discussed. 相似文献
205.
Anders E af W?hlberg 《International journal of occupational safety and ergonomics》2006,12(3):281-296
A study was undertaken to investigate whether driver celeration (overall mean speed change) behavior can predict traffic accident involvement. Also, to test whether acceleration, deceleration or the combined celeration measure was the better predictor. Bus driver celeration behavior was measured repeatedly in real traffic, driving en route, and correlated with accidents for which the drivers were deemed at least partly responsible. Correlations around .20 were found in several samples between celeration behavior and culpable accidents for a 2-year period. The results show that although celeration behavior is only semi-stable over time, it predicts with some accuracy individual accident involvement over 2 years. The predictive power of acceleration and deceleration was slightly lower than the combined measure, in accordance with theory. The correlations found were strong enough to warrant the use of celeration behavior as a predictive variable for transportation companies in their safety work. 相似文献
206.
Andersson P Byegård J Tullborg EL Doe T Hermanson J Winberg A 《Journal of contaminant hydrology》2004,70(3-4):271-297
Experiments were conducted at the Asp? Hard Rock Laboratory in order to improve the understanding of radionuclide retention properties of fractured crystalline bedrock in the 10-100 m scale (TRUE Block Scale Project, jointly funded by ANDRA, ENRESA, Nirex, JNC, Posiva and SKB). A series of tracer experiments were performed using sorbing tracers in three different flow paths. The different flow paths had Euclidian lengths of 14, 17 and 33 m, respectively, and one to three water conducting structures. Four tests were performed using different cocktails made up of radioactive sorbing tracers (22,24Na+, 42K+, 47Ca2+, 85Sr2+, 83,86Rb+, 131,133Ba2+ and 134,137Cs+). For each tracer injection, the breakthrough of sorbing tracers was compared to the breakthrough of a conservative tracer, 82Br-, 131I-, HTO and 186ReO4-, respectively. In the two longer flow paths, no breakthrough of 83Rb+ and 137Cs+ was observed after 8 months of pumping. Selected tracer tests were subject to basic modelling in which a one-dimensional (1D) advection-dispersion model, including surface sorption, and an unlimited matrix diffusion were used for the interpretation of the results. The results of the modelling indicated that there is a slightly higher mass transfer into a highly porous material in the block-scale experiment compared with in situ experiments performed over shorter distances and significantly higher than what would have been expected from laboratory data obtained from studies of the interactions in nonaltered intact rock. 相似文献
207.
Soler JJ Peralta-Sánchez JM Flensted-Jensen E Martín-Platero AM Møller AP 《Die Naturwissenschaften》2011,98(9):807-813
Fitness benefits associated with the development of a costly immune system would include not only self-protection against
pathogenic microorganisms but also protection of host offspring if it reduces the probability and the rate of vertical transmission
of microorganisms. This possibility predicts a negative relationship between probabilities of vertical transmission of symbionts
and level of immune response that we here explore inter-specifically. We estimated eggshell bacterial loads by culturing heterotrophic
bacteria, Enterococcus, Staphylococcus and Enterobacteriaceae on the eggshells of 29 species of birds as a proxy of vertical transmission of bacteria from mother to offspring. For this
pool of species, we also estimated innate immune response (natural antibody and complement (lysis)) of adults, which constitute
the main defence against bacterial infection. Multivariate general linear models revealed the predicted negative association
between natural antibodies and density of bacteria on the eggshell of 19 species of birds for which we sampled the eggs in
more than one nest. Univariate analyses revealed significant associations for heterotrophic bacteria and for Enterobacteriaceae, a group of bacteria that includes important pathogens of avian embryos. Therefore, these results suggest a possible trans-generational
benefit of developing a strong immune system by reducing vertical transmission of pathogens. 相似文献
208.
Differences in Long-term Medical Consequences Depending on Impact Direction Involving Passenger Cars
Helena Stigson Markus Gustafsson Cecilia Sunnevång Maria Krafft Anders Kullgren 《Traffic injury prevention》2015,16(4):S133-S139
Objective: There is limited knowledge of the long-term medical consequences for occupants injured in car crashes in various impact directions. Thus, the objective was to evaluate whether injuries leading to permanent medical impairment differ depending on impact direction.Methods: In total, 36,743 injured occupants in car crashes that occurred between 1995 and 2011 were included. All initial injuries (n = 61,440) were classified according to the Abbreviated Injury Scale (AIS) 2005. Injured car occupants were followed for at least 3 years to assess permanent medical impairment. The data were divided into different groups according to impact direction and levels of permanent impairment. The risk of permanent medical impairment was established for different body regions and injury severity levels, according to AIS.Results: It was found that almost 12% of all car occupants sustained a permanent medical impairment. Given an injury, car occupants involved in rollover crashes had the highest overall risk to sustain a permanent medical impairment. Half of the head injuries leading to long-term consequences occurred in frontal impacts. Far-side occupants had almost the same risk as near-side occupants. Occupants who sustained a permanent medical impairment from cervical spine injuries had similar risk in all impact directions (13%) except from rollover (17%). However, these injuries occurred more often in rear crashes. Most of the injuries leading to long-term consequences were classified as minor injuries by AIS for all impact directions.Conclusions: Studying crash data from a perspective of medical impairment is important to identify injuries that might not be prioritized only considering the AIS but might lead to lower quality of life for the occupant and also costs for society. These results can be used for road transport system strategies and for making priority decisions in vehicle design. 相似文献
209.
Eugene E. Ezebilo Mattias Boman Leif Mattsson Anders Lindhagen Werner Mbongo 《Journal of Environmental Planning and Management》2015,58(2):283-296
In Sweden there is a strong tradition of using nature areas for outdoor recreation. This paper reports on a study which explored preferences and willingness to pay for outdoor recreation close to home (≤100 km away from home and ≤24 hours stay at a recreation site) using the contingent valuation method. The data originated from a mail survey that involved Swedish residents who were randomly selected from a national register. An ordinary least squares regression model was used to account for factors influencing willingness to pay. The results showed that approximately 50% of the respondents used nature areas close to their home for recreation and their average frequency of visits to these areas was 74 times annually. Areas dominated by forests were the most preferred, followed by water. The respondents were willing to pay approximately 7200 SEK (US$1080) annually. Their willingness to pay was influenced by factors such as type of nature area, distance to and time spent at the recreation site and income. The results provide one input to the land use planning process by considering the demand for nature-based outdoor recreation close to home. 相似文献
210.
Lasse Marohn Enno Prigge Karsten Zumholz Andreas Klügel Heike Anders Reinhold Hanel 《Marine Biology》2009,156(5):927-933
Otolith microchemistry is widely used as a tool to track individual migration pathways of diadromous fish under the assumption
that the elemental composition of fish otoliths is directly influenced by the physicochemical properties of the surrounding
water. Nevertheless, several endogenous factors are reported to affect element incorporation into fish otoliths and might
lead to misinterpretations of migration studies. This study experimentally examined the influence of eight different diets
on the microchemical composition of European eel (Anguilla anguilla) otoliths using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Seven natural prey types and one
artificial diet were fed during 8 weeks in freshwater circuits. Results show for the first time that food has no significant
influence on the incorporation of Na, Sr, Ba, Mg, Mn, Cu and Y into European eel otoliths. This indicates that the incorporation
of elements usually chosen for migration studies is not affected by diet and that individual feeding behaviour of A. anguilla will not lead to any misinterpretation of migration pathways. 相似文献