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611.
Mie H. Sichlau Jørgen L. S. Hansen Thorbjørn J. Andersen Benni W. Hansen 《Marine Biology》2011,158(3):665-676
Distribution, abundance and age of diapause eggs from three species of calanoid copepods (in particular from Acartia spp. most likely Acartia tonsa, and Centropages hamatus and less numerous from Temora longicornis) were recorded in sediment profiles by enumerating hatched nauplii from incubated sediment samples. Phytoplankton pigments
and 210Pb and 137Cs analyses indicated that the sedimentation regimes were different between two southern and two northern stations of the
island Funen, Denmark. Significant variations in vertical distribution, abundance and mortality of diapause eggs were found
between the stations. Dating of the sediment cores suggested a ~70-year maximum age of viable eggs on the northernmost stations,
and ~28 year at the southernmost stations. The eggs exhibited a significantly higher mortality rate at the southernmost stations
compared with the northernmost, 0.35–0.53 year−1 vs. 0.07–0.08 year−1 with no systematic pattern among species. The differences in abundance, mortality and age of the diapause eggs are suggested
to be due to the sediment characteristics in which they are buried. 相似文献
612.
613.
Twenty years of stream restoration in Finland: little response by benthic macroinvertebrate communities 总被引:1,自引:0,他引:1
Louhi P Mykr? H Paavola R Huusko A Vehanen T M?ki-Pet?ys A Muotka T 《Ecological applications》2011,21(6):1950-1961
The primary focus of many in-stream restoration projects is to enhance habitat diversity for salmonid fishes, yet the lack of properly designed monitoring studies, particularly ones with pre-restoration data, limits any attempts to assess whether restoration has succeeded in improving salmonid habitat. Even less is known about the impacts of fisheries-related restoration on other, non-target biota. We examined how restoration aiming at the enhancement of juvenile brown trout (Salmo trutta L.) affects benthic macroinvertebrates, using two separate data sets: (1) a before-after-control-impact (BACI) design with three years before and three after restoration in differently restored and control reaches of six streams; and (2) a space-time substitution design including channelized, restored, and near-natural streams with an almost 20-year perspective on the recovery of invertebrate communities. In the BACI design, total macroinvertebrate density differed significantly from before to after restoration. Following restoration, densities decreased in all treatments, but less so in the controls than in restored sections. Taxonomic richness also decreased from before to after restoration, but this happened similarly in all treatments. In the long-term comparative study, macroinvertebrate species richness showed no difference between the channel types. Community composition differed significantly between the restored and natural streams, but not between restored and channelized streams. Overall, the in-stream restoration measures used increased stream habitat diversity but did not enhance benthic biodiversity. While many macroinvertebrates may be dispersal limited, our study sites should not have been too distant to reach within almost two decades. A key explanation for the weak responses by macroinvertebrate communities may have been historical. When Fennoscandian streams were channelized for log floating, the loss of habitat heterogeneity was only partial. Therefore, habitat may not have been limiting the macroinvertebrate communities to begin with. Stream restoration to support trout fisheries has strong public acceptance in Finland and will likely continue to increase in the near future. Therefore, more effort should be placed on assessing restoration success from a biodiversity perspective using multiple organism groups in both stream and riparian ecosystems. 相似文献
614.
A recent trend is to estimate landscape metrics using sample data and cost-efficiency is one important reason for this development.
In this study, line intersect sampling (LIS) was used as an alternative to wall-to-wall mapping for estimating Shannon’s diversity
index and edge length and density. Monte Carlo simulation was applied to study the statistical performance of the estimators.
All combinations of two sampling designs (random and systematic distribution of transects), four sample sizes, five transect
configurations (straight line, L, Y, triangle, and quadrat), two transect orientations (fixed and random), and three configuration
lengths were tested, each with a large number of simulations. Reference was 50 photos of size 1 km2, already manually delineated in vector format by photo interpreters using GIS environment. The performance was compared by
root mean square error (RMSE) and bias. The best combination for all three metrics was found to be the systematic design and
as response design the straight line configuration with random orientation of transects, with little difference between the
fixed and random orientation of transects. The rate of decrease of RMSE for increasing sample size and line length was studied
with a mixed linear model. It was found that the RMSE decreased to a larger degree with the systematic design than the random
one, especially with increasing sample size. Due to the nonlinearity in the definition of Shannon diversity estimator its
estimator has a small and negative bias, decreasing with sample size and line length. Finally, a time study was conducted,
measuring the time for registration of line intersections and their lengths on non-delineated aerial photos. The time study
showed that long sampling lines were more cost-efficient than short ones for photo-interpretation. 相似文献
615.
Yi-Huey?Chen Wei-Chun?Cheng Hon-Tsen?YuEmail author Yeong-Choy?KamEmail author 《Behavioral ecology and sociobiology》2011,65(12):2329-2339
The rhacophorid frog, Kurixalus eiffingeri, is one of only a few frog species that exhibits polyandry and paternal care of eggs. Previous studies predicted that multiple
paternity within an egg clutch could influence the degree of paternal care and reproductive strategies. We used microsatellite
DNA markers to assess the prevalence of multiple paternity within egg clutches and the relationship between male paternal
care and the percent of male’s genetic contribution to the clutch, i.e., paternal share. We conducted field observations of paternal care and collected tissues from both male frogs and tadpoles
for parentage analyses. Our results showed that at least five out of 31 egg clutches had multiple paternity. Attending males
were always the genetic fathers of some, if not all of the eggs in the clutch they guarded. All egg clutches except one were
attended by one male frog but the attending male did not necessarily sire the majority of offspring. Multiple paternity in
all cases consisted of two fathers and one mother and most likely resulted from synchronous polyandry. Paternal care effort
correlated significantly with the male’s genetic contribution to the clutch, suggesting that male frogs adjust the effort
expended in care in response to paternal share. In addition, our results suggest that externally fertilizing species with
parental care and multiple paternity may develop novel reproductive and behavioral strategies to safeguard their parental
investment and overcome sperm competition. 相似文献
616.
E. Petter Axelsson Joakim Hj?lt��n Thomas G. Whitham Riitta Julkunen-Tiitto Gilles Pilate Anders Wennstr?m 《Chemoecology》2011,21(3):161-169
Bioassays with a non-target slug (Deroceras spp.) and chemical analyses were conducted using leaf tissue from already existing genetically modified insect-resistant
aspen trees to examine whether genetic modifications to produce Bacillus thuringiensis (Bt) toxins could affect plant phytochemistry, which in turn might influence plant–herbivore interactions. Three major patterns
emerged. First, two independent modifications for Bt resistance affected the phytochemical profiles of leaves such that both
were different from the isogenic wild-type (Wt) control leaves, but also different from each other. Among the contributors
to these differences are substances with a presumed involvement in resistance, such as salicortin and soluble condensed tannins.
Second, bioassays with one Bt line suggest that the modification somehow affected innate resistance (“Innate” is used here
in opposition to the “acquired” Bt resistance) in ways such that slugs preferred Bt over Wt leaves. Third, the preference
test suggests that the innate resistance in Bt relative to Wt plants may not be uniformly expressed throughout the whole plant
and that leaf ontogeny interacts with the modification to affect resistance. This was manifested through an ontogenetic determined
increase in leaf consumption that was more than four times higher in Bt compared to Wt leaves. Our result are of principal
importance, as these indicate that genetic modifications can affect innate resistance and thus non-target herbivores in ways
that may have commercial and/or environmental consequences. The finding of a modification–ontogeny interaction effect on innate
resistance may be especially important in assessments of GM plants with a long lifespan such as trees. 相似文献
617.
Impacts of offshore wind farms on marine fauna are largely unknown. Therefore, one commonly adheres to the precautionary principle, which states that one shall take action to avoid potentially damaging impacts on marine ecosystems, even when full scientific certainty is lacking. We implement this principle by means of a statistical power analysis including spatial factors. Implementation is based on geostatistical simulations, accommodating for zero-inflation in species data. We investigate scenarios in which an impact assessment still has to be carried out. Our results show that the environmental conditions at the time of the survey is the most influential factor on power. This is followed by survey effort and species abundance in the reference situation. Spatial dependence in species numbers at local scales affects power, but its effect is smaller for the scenarios investigated. Our findings can be used to improve effectiveness of the economical investment for monitoring surveys. In addition, unnecessary extra survey effort, and related costs, can be avoided when spatial dependence in species abundance is present and no improvement on power is achieved. 相似文献
618.
Electrothermal atomic absorption spectrometry methods with Zeeman effect background correction (Z-GFAAS) for determination
of As, Sb, Se, Ag, Cd, Pb, Cu, Fe, Zn, Cr, and Ni in water and sludge samples were developed. The measurements using Z-GFAAS
and variable magnetic field at the three-field dynamic mode permit the sensitivity adaptation for higher analytical concentrations.
Calibration ranges were expanded over two orders of magnitude within one measurement run by the applying three-field dynamic
mode of this correction system. There are presented calibration data, furnace programs, modifiers, and microwave digestion
programs of the obviously monitored elements in the environmental samples. Very low detection limits (3σ criterion) were obtained.
Quality assurance was checked by the suitable CRM. The study brings simultaneous determination of the samples with different
element concentration range and different sample matrixes, as an important application information for an analyst working
in the area of the eco-analytical research. 相似文献
619.
?ehnaz ?ener Erhan Sener Remzi Karag��zel 《Environmental monitoring and assessment》2011,173(1-4):533-554
The appropriate site selection for waste disposal is one of the major problems in waste management. Also, many environmental, economical, and political considerations must be adhered to. In this study, landfill site selection is performed using the Geographic Information System (GIS), the Analytical Hierarchy Process (AHP), and the remote sensing methods for the Senirkent?CUluborlu Basin. The basin is located in the E?irdir Lake catchment area, which is one of the most important fresh water in Turkey. So, waste management must be regulated in the basin. For this aim, ten different criteria (lithology, surface water, aquifer, groundwater depth, land use, lineaments, aspect, elevation, slope, and distance to roads) are examined in relation to landfill site selection. Each criterion was identified and weighted using AHP. Then, each criterion is mapped using the GIS technique, and a suitability map is prepared by overlay analyses. The results indicate that 96.3% of the area in the basin is unsuitable; 1.6%, moderately suitable; and 2.1%, most suitable. Finally, suitable regions in the basin are determined for solid waste landfill disposal and checked in the field. The selected and investigated regions are considered to be suitable for the landfill. 相似文献
620.
Land degradation assessment by geo-spatially modeling different soil erodibility equations in a semi-arid catchment 总被引:1,自引:0,他引:1
Saygın SD Basaran M Ozcan AU Dolarslan M Timur OB Yilman FE Erpul G 《Environmental monitoring and assessment》2011,180(1-4):201-215
Land degradation by soil erosion is one of the most serious problems and environmental issues in many ecosystems of arid and semi-arid regions. Especially, the disturbed areas have greater soil detachability and transportability capacity. Evaluation of land degradation in terms of soil erodibility, by using geostatistical modeling, is vital to protect and reclaim susceptible areas. Soil erodibility, described as the ability of soils to resist erosion, can be measured either directly under natural or simulated rainfall conditions, or indirectly estimated by empirical regression models. This study compares three empirical equations used to determine the soil erodibility factor of revised universal soil loss equation prediction technology based on their geospatial performances in the semi-arid catchment of the Saraykoy II Irrigation Dam located in Cankiri, Turkey. A total of 311 geo-referenced soil samples were collected with irregular intervals from the top soil layer (0-10?cm). Geostatistical analysis was performed with the point values of each equation to determine its spatial pattern. Results showed that equations that used soil organic matter in combination with the soil particle size better agreed with the variations in land use and topography of the catchment than the one using only the particle size distribution. It is recommended that the equations which dynamically integrate soil intrinsic properties with land use, topography, and its influences on the local microclimates, could be successfully used to geospatially determine sites highly susceptible to water erosion, and therefore, to select the agricultural and bio-engineering control measures needed. 相似文献