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971.
Konstantinos Ganias 《Marine Biology》2008,155(3):293-301
Using previously published histological data on multiple, monthly samples of Sardina pilchardus collected in the central Aegean and Ionian Seas (September 1999–August 2000, and November 2000–February 2001), the Mediterranean
sardine was treated as a case study to investigate the biological characteristics of ephemeral spawning aggregations in multiple-spawning
clupeoids. Actively spawning (Day0) females in the Mediterranean sardine, i.e., the daily class of spawners caught a few hours prior, during, or after the spawning
act, were shown to separate spatially from late (Day1+) spawners and non-spawning females, taking with them a large proportion of conspecific males which were also in advanced
spawning condition and in better somatic condition compared to the remaining population. In addition, information from 28
stocks of multiple-spawning clupeoids from a wide range of geographic locations, belonging to 14 species and 2 families (Engraulidae
and Clupeidae), was reviewed and analyzed pertinent to the formation of ephemeral spawning aggregations. Results from the
latter analysis indicated similar patterns of spatial segregation of Day0 spawners in the reviewed clupeoid stocks as in the Mediterranean Sardine, which strongly suggested that the formation of
ephemeral spawning aggregations is a common behavioral trait among multiple-spawning clupeoids.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
972.
Madeleine Beekman Stephen J. Martin Falko Drijfhout Benjamin P. Oldroyd 《Behavioral ecology and sociobiology》2007,61(12):1847-1853
Anarchy, where honeybee workers produce males in the presence of a queen, is extremely rare in natural honeybee populations,
suggesting that there are colony-level costs associated with being anarchistic. Yet, no significant costs have yet been identified.
A possible reason for this may be that researchers have only focused on the behaviour of anarchistic workers, which have been
shown to perform worker-tasks as do wild-type workers. Possibly, therefore, costs associated with anarchy should be sought
in anarchistic queens and not workers. A potential cost could be a lower survival rate of eggs laid by anarchistic queens
perhaps because their egg-marking signal is not as clear as that of a wild-type queen. In this paper, we determined the removal
rate of eggs laid by anarchistic queens in standard worker-policing bioassays. Our results show that eggs laid by anarchistic
queens are removed at a higher rate than eggs laid by wild-type queens. This does not seem to be due to differences in hydrocarbons
found on the surface of eggs, as both egg types showed the same alkanes and alkenes in similar proportions. We postulate that
higher removal rates of queen-laid eggs due to recognition errors may be one reason that anarchy is rare in natural honeybee
populations. 相似文献
973.
Increased salinity in spawning and nursery grounds in the Savannah River estuary was cited as the primary cause of a 97% decrease
in adult striped bass (Morone saxatilis) and a concomitant 96% decrease in striped bass egg production. Restoration efforts focused on environmental remediation
and stock enhancement have resulted in restored salinity patterns and increased egg and adult abundances. However, future
water needs or harbor development may preclude further recovery by reducing freshwater inflow or increasing salinity intrusion.
To assess the effect of potential changes in the salinity regime, we developed models relating discharge, tidal phase, and
salinity to striped bass egg and early larval survival and re-cast these in a quantitative Bayesian belief network. The model
indicated that a small upstream shift (≤1.67 km) in the salinity regime would have the least impact on striped bass early
life history survival, whereas shifts >1.67 km would have progressively larger impacts, with a 8.33-km shift potentially reducing
our estimated survival probability by >28%. Such an impact could have cumulative and long-term detrimental effects on the
recovery of the Savannah River striped bass population. The available salinity data were collected during average and low
flows, so our model represents some typical and some extreme conditions during a striped bass spawning season. Our model is
a relatively simplistic, “first-order” attempt at evaluating potential effects of changes in the Savannah River estuarine
salinity regime and points to areas of concern and potential future research. 相似文献
974.
975.
976.
977.
Bioremediation process on Brazil shoreline 总被引:1,自引:0,他引:1
GOAL, SCOPE AND BACKGROUND: Bioremediation technique can be considered a promising alternative to clean oil spills using microbial processes to reduce the concentration and/or the toxicity of pollutants. To understand the importance of this work we must know that there is only little research performed to date using bioremediation techniques to clean oil spills in tropical countries. So, the main objective of this work is to analyze the behavior of a laboratory's bioremediation test using nutrients on coastal sediments. METHODS: The bioremediation process is followed through geochemical analysis during the tests. This organic material is analyzed by medium pressure liquid chromatography (MPLC), gas chromatography/flame ionization detection (GC/FID) and gas chromatography/ mass spectrometry. By microbial counting, the number of total bacteria and degrading bacteria is determined during the experiments, in order to confirm the effectiveness of the bioremediation process. The seawater obtained throughout the bioremediation process is analyzed for nutrients grade (phosphate and ammonium ions) and also for its toxicity (Microtox tests) due the presence of hydrocarbons and fertilizer. RESULTS: The results from the geochemical analyses of the oil show a relative decrease in the saturated hydrocarbon fraction that is compensated by a relative enrichment on polar compounds. It's confirmed by the fingerprint evaluation where it is possible to see a complete reduction of the normal alkanes followed by isoprenoids. Seawater analysis done by toxicity and nutrients analysis, such as microbial counting (total and degrading bacteria), confirm the fertilizer effectiveness during the bioremediation process. DISCUSSION: Results from simulating test using NPK, a low-price plant fertilizer, suggest that it's able to stimulate the degradation process. Results from medium pressure liquid chromatography (MPLC), done at two different depths (surface and subsurface), show different behavior during the biodegradation process where the later is seen to be more susceptible to microbial attack. Data from bioremediation unit shows a bigger reduction of the saturated fraction, followed by some smaller reduction of aromatic fractions, compensated by a relative increase from polar compounds (NSO). n-C17/pristane, n-C18/ fitane and pristane/fitane rates show constant values for the unity control, different from bioremediation samples which have a significant reduction, especially on subsurface areas, where a strong fall in the rates, seen to be reduced to zero over twenty days, had occurred during the first ten days. However, sample surfaces are reduced to zero in thirty days of experiments, proving that biodegradation is better on subsurfaces. Gaseous chromatography/mass spectrometry (CG/MS) analysis shows constant values to cyclic biomarker rates and aromatic compounds, suggesting that the biodegradation process is not strong enough to reduce these composites. Microbial analysis shows a reduction on heterotrophic (total bacteria) number from control unit, probably because the bacteria uses the spill oil like carbon source and energy. However, the number increases on bioremediation unit, because it uses NPK like a biostimulator. The hydrocarbonoclastic number isn't enough on the first moment, but it's detected after 30 days and quantified in all units, showing big values especially in bioremediation. Toxicity tests confirm that NPK fertilizer does not intoxicate the shoreline during the application of the bioremediation technique. Some nutrient concentration shows high values of ammonium and phosphate per bioremediation unit, reducing by the end of the experiment. CONCLUSIONS: Results reached the goal, finding a proper nutrient (NPK fertilizer) to stimulate the biodegradation process, growing bacteria responsible for reducing impact-contaminated coast ambient by oil spills. Chemical analysis of oil shows a reduction in the saturated fraction with a relative enrichment in polar composites (NSO) and the aromatic fraction from oil remaining constant. Subsurface samples show more biodegradation than surface samples, probably because the first one has higher humidity. Linear alcanes are more biodegraded than isoprenoids, confirming the biodegradation susceptibility order. Saturated cyclic biomarkers and aromatic compounds show constant behavior maybe because the nutrients or time was not enough for microorganismic attack. Fertilizer does not demonstrate any toxic effects in local biota so that it does not compromise the technique applicability and the environment is not saturated by nutrients during the simulation, especially since the coastal environment is an open system affected daily by tides. Therefore, bioremediation tests can be classified as moderate, reaching level 5 in the classification scale by Peters & Moldowan (1993). RECOMMENDATIONS AND PERSPECTIVES: The use of marine environment by the petroleum industry on exploration, production and transportation operation, transform this oil to become the most important pollutant in the oceans. Bioremediation is an important technique used to clean spilled oil impacting on shorelines, accelerating the biodegradation process by using fertilizer growing the microorganisms responsible for decontaminating the environment. We recommend confirming the efficiency of NPK nutrient used on bioremediation simulating experiments on beaches, while monitoring the chemical changes long-term. NPK fertilizer can be used to stimulate the biodegradation process on shoreline impacted by spilled oil. 相似文献
978.
Marko S. Markov 《The Environmentalist》2007,27(4):457-463
The interest toward clinical application of magnetic and electromagnetic stimulation increases worldwide. Numerous publications
discussed the possibility exogenous magnetic and electromagnetic fields to initiate effects on various biological processes,
which are of critical importance for healing of different injuries and pathologies. Today, magnetic and electromagnetic fields
are increasingly utilized for treatment of various musculoskeletal injuries and pathologies. For musculoskeletal injuries
and post-surgical, post traumatic and chronic wounds, reduction of edema is a major therapeutic factor in the acceleration
of pain and stress relief, and thus contribute to healing processes. Electromagnetic and magnetic fields appear to be unique
in their safety during clinical use. The application of this new modality will be facilitated by searching for biophysical
mechanisms of action as well as by establishing exact dosimetry of application. In that respect basic science research needs
to be developed in parallel with clinical applications. Magnetotherapy provides a non-invasive, safe, and easy method to directly
treat the site of injury, the source of pain and inflammation, and other types of injury. Unfortunately, there are many obstacles
that magnetotherapy has to overcome—both from the mainstream medicine as well as from the manufacturers and distributors of
magnetic devices. The physical principle of magnetism as well as the physiological bases for the use of magnetic field for
tissue repair are subjects of this review. 相似文献
979.
MIRIAM MIRANDA CAREL DIEPERINK PIETER GLASBERGEN 《Environment, Development and Sustainability》2007,9(1):1-19
This article analyses the application of voluntary environmental agreements (VEAs) in watershed protection in Costa Rica.
Next to an involvement of private energy firms, the Costa Rican state, and farmers, the participation of NGOs is a remarkable
feature. From an analysis of these multi-stakeholder arrangements, it is concluded that these arrangements bring benefits
to all actors involved. VEAs have been able to grow as powerful policy instruments, generating positive environmental effects.
Essential is their embedded ness in a broader set of environmental policies, especially related to forest management
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
980.
We documented valley and channel characteristics and wood loads in 19 reaches of forested headwater mountain streams in the
Bighorn National Forest of northern Wyoming. Ten of these reaches were in the Upper Tongue River watershed, which has a history
of management including timber harvest, tie floating, and road construction. Nine reaches were in the North Rock Creek watershed,
which has little history of management activities. We used these data to test hypotheses that (i) valley geometry correlates
with wood load, (ii) stream gradient correlates with wood load, and (iii) wood loads are significantly lower in managed watersheds
than in otherwise similar unmanaged watersheds. Statistical analyses of the data support the first and third hypotheses. Stream
reaches with steeper valley side slopes tend to have higher wood loads, and reaches in managed watersheds tend to have lower
wood loads than reaches in unmanaged watersheds. Results do not support the second hypothesis. Shear stress correlated more
strongly with wood load than did stream gradient, but statistical models with valley-scale variables had greater explanatory
power than statistical models with channel-scale variables. Wood loads in stream reaches within managed watersheds in the
Bighorn National Forest tend to be two to three times lower than wood loads in unmanaged watersheds. 相似文献