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191.
The number, size, and carbon and nitrogen contents of eggs in the pouches of a euphausiid crustacean, Nematoscelis difficilis
Hansen, were examined. A clear linear relationship exists between the number of eggs in the pouch and the body weight of the maternal euphausiid. The eggs are not spherical in shape, and the size of eggs is greater in larger egg masses. The carbon content of the egg masses (50.2%) is higher than that of the bodies (40.7%). The carbon: nitrogen ratio (C/N) is also higher in the egg masses than in the bodies of euphausiids. The carbon content of the eggs is equivalent to 28.4% of the body carbon, the nitrogen content to 19.2% of the body nitrogen. 相似文献
192.
Kanjana Adulyanukosol Surasak Thongsukdee Takeshi Hara Nobuaki Arai Makoto Tsuchiya 《Marine Biology》2007,151(5):1887-1891
The seagrass beds at Muk Island and Talibong Island in Thailand are important areas for dugong (Dugong dugon) feeding and reproduction. We used opportunistic observations during aerial surveys to investigate dugong mating behavior
in shallow water areas near Talibong Island on three different days. The mating pattern was categorized by five stages: (1)
following: the male followed the female, (2) approaching and stimulating: the male approached and muzzled the female, (3)
pairing: both male and female swam in parallel, ventral to ventral or dorsal to dorsal side, (4) mounting: the male copulated
with the female, and (5) separating: the male and female swam in different directions. Parental care of calves included one
observation of a cow embracing her neonatal calf by the flippers. 相似文献
193.
Susanna Reid Barry Smit Wayne Caldwell Suzanne Belliveau 《Mitigation and Adaptation Strategies for Global Change》2007,12(4):609-637
A vulnerability approach to climate change adaptation research is employed to explore prospects of agricultural adaptation
to climatic variability and change. The methodological approach focuses on the system of concern, in this case, farms in Perth
County, Ontario. Twenty-five interviews and four focus groups with farmers were used to identify climate risks on farms, and
to document farmers’ responses to conditions and risks associated with climate and weather. The information collected describes
a complex decision-making environment, with many forces both external and internal to the farm operation influencing management
decisions. Within this environment, climate and weather are consistently referred to as a significant force influencing both
farm operations and management decisions. Farmers have, however, developed a wide-range of anticipatory and reactive management
strategies to manage climate risks. While these have potential to address future climate-related risks and opportunities,
there are limits to adaptation, and an increase in the frequency of extreme events may exceed their adaptive capacities. Farmers
are also generally unaware and/or unconcerned about future climate change, which could constrain opportunities to adopt long-term
climate change adaptations. 相似文献
194.
It is desirable when drawing up a maritime traffic environmental project or a project for consolidating port and harbour facilities, that the safety of the maritime environment for shipping-traffic is assessed quantitatively, and that the rationale of a given project and the proposed safety measures are evaluated in an objective manner.In this report, the system flow and procedures to integrally assess the safety of the maritime traffic environment by systematically combining various simulation techniques are discussed first.Subsequently, the quantitative risk evaluation procedure for collisions of ships in waters with a high traffic density, among the assessment procedures above, and an outline of the shipping traffic flow simulation capable of reproducing ships′ movements, are described. In evaluating the results of simulations, a method introducing Subjective Judgement values (SJ-values) as indexes manifesting the subjective degree of danger felt by shiphandlers, is shown. The SJ-values were experimentally determined from simulator experiments using parameters representing the relation ship with other ships proceeding in the vicinity.Finally, some of the results of studies conducted for the recent construction of new LNG berths in Tokyo Bay are introduced as an example of practical safety assessment in this field. 相似文献
195.
196.
197.
Izumi Noguchi Kentaro Hayashi Masahide Aikawa Tsuyoshi Ohizumi Yukiya Minami Moritsugu Kitamura Akira Takahashi Hiroshi Tanimoto Kazuhide Matsuda Hiroshi Hara 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):67-75
Temporal trends of non-sea salt (nss-) sulfate and nitrate were analyzed from nationwide precipitation chemistry measurements
provided by the Ministry of the Environment (MOE) for the 1988–2002 fiscal years (April–March). The concentrations and deposition
of nss-sulfate were found to be decreasing, and those of nitrate were stable or slightly increasing at most sites. These deposition
trends were discussed from the viewpoint of emissions of SO2 and NOX during the period of interest. Because monitoring techniques have changed in the number of active sites, samplers, and analytical
methods during the operation period, the median of all annual depositions measured in Japan in a specific year was selected
as the annual representative. The contribution of specific emission sources was also calculated for 1990 on the basis of the
nss-sulfate and nitrate deposition in Japan obtained with a model simulation in which the model did not include volcanic emissions
from Mt. Oyama, Miyakejima Island, which began to erupt suddenly and violently in 2000. For nss-sulfate, the calculated deposition
agrees well with the intensity and trends of the median up to 1999. After 2000, a higher deposition than calculated in the
preceding years was evident, which is attributable to the volcanic SO2 from Mt. Oyama. For nitrate, both the calculated and observed depositions were slightly increasing; however, the calculation
was found to exceed the observation. 相似文献
198.
199.
Little is known about the metabolism of deep-living, benthic invertebrates, despite its importance in estimating energy flow through individuals and populations. To evaluate the effects of depth and broad taxonomic group/locomotory mode, we measured the respiration rates of 25 species of benthic decapod crustaceans and 18 species of echinoderms from the littoral zone to the deep slope of Hawaii. Specimens were collected by hand, trap, or submersible and maintained in the laboratory at temperatures close to ambient temperatures recorded at the time of collection. After acclimatization to laboratory conditions, oxygen consumption was measured for each individual in closed chambers. Overall, crustaceans had higher metabolic rates than echinoderms, and within the crustaceans, caridean shrimps had higher rates than crabs and lobsters. These differences are probably related to locomotory mode and general levels of activity. At in situ environmental temperatures, metabolic rates of deeper-living invertebrates are much lower than those of shallower living species, but this decline is explained by changes in temperature. When the data were compared with similar data sets collected off California and in the Mediterranean, Hawaiian crabs, lobsters, and echinoderms had lower metabolic rates than similar species in the other regions after adjustments for temperature were made. Some of these differences could be methodological. Regional food web models should use broad taxonomic groupings and region-specific data when possible. 相似文献
200.
The present paper reports how stand size-structure dynamics due to competition between different-sized trees affect long-term forested water balance in Japanese cool-temperate planted stands (evergreen coniferous Cryptomeria japonica and deciduous coniferous Larix kaempferi stands) using a fully coupled multi-layered meteorological surface physics—terrestrial ecosystems model. The simulation captured the well-known annual variation in leaf area index (LAI) accurately with stand age in monocultured and even-aged stands; the occurrence of maximum LAI during the early growth stage and then a gradual decline followed by a steady state after the maximum LAI. The simulations also detected a high dependency of annual evapotranspiration (AETr) on LAI with stand age that is well known by prior observational researches. In the C. japonica (shade-tolerant late-successional species) stand, the relationship between annual net primary productivity of an individual tree (NPPind) and individual tree mass (w) changed from linear to a convex curve during self-thinning, indicating that the degree of asymmetric tree competition intensified with forest stand development. The higher degree of competitive asymmetry characterized by the convex-shaped NPPind-w relationship produced greater size inequality, i.e., the formation of trees stratified by height. Under such conditions, AETr and annual transpiration (ATr) were mainly regulated by larger trees. On the other hand, the NPPind-w relationships in the L. kaempferi (shade-intolerant early-successional species) stand were linear throughout the simulated period, indicating the lower degree of competitive asymmetry. Under such conditions, the growth of intermediate-sized trees was enhanced and these trees became a dominant source of AETr (and also ATr) during self-thinning. Furthermore, the sensitivity analysis of the effects of ecophysiological parameters such as foliage profile (i.e., vertical distribution of leaf area density) of an individual tree (distribution pattern is described by the parameter η), the maximum carboxylation velocity (Vcmax0) and biomass allocation pattern of individual plant growth (μ1) on AETr, ATr and annual runoff (ARoff) showed that the temporal trends of AETr, ATr, ARoff and NPPind-w relationships were completely the same as those in the control simulations. However, the NPPind-w relationship during self-thinning indicated higher degrees of competitive asymmetry when η or Vcmax0 were greater than those in the control simulation and generated greater AETr and ATr and thus smaller ARoff. We found that more asymmetric tree competition brings about greater size inequality between different-sized trees and thus more evapotranspiration and less runoff in a forest stand. Overall, our simulation approach revealed that not only LAI dynamics but also plant competition, and thus size-structure dynamics, in a forest ecosystem are essential to long-term future projections of forested water balance. 相似文献