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71.
Evaluating the impacts of point source discharges on fish species in estuarine environments can be challenging because of
a paucity of resident species. We evaluated the biology of rock gunnel (Pholis gunnellus) at three relatively uncontaminated sites in the Bay of Fundy, along the Atlantic coast of Canada. Rock gunnel are seasonally
resident (April to November) in tide pools, but little was known about their life history in Atlantic Canada or their potential
for use for monitoring environmental quality. Fish were collected between April and November, and ranged from 2.46 g--15.2~g
in weight and 97 mm-170 mm in length, with a maximum age of 7 years. Both males and females were similar in size, and both
reached sexual maturity at a size of 5.5 g. Organ weights and condition indices of fish were stable from spring when they
returned from offshore (April to May) until late summer (August to September), but fall fish (October to November) had slightly
larger gonads, livers and condition indices. Rock gunnel may be a useful indicator to provide insight into local impacts of
point sources over a short time period. However, they do not provide adequate information on reproductive development and
performance since they are not exposed to onshore contaminants during the periods of gonadal development that have most commonly
found to be sensitive to anthropogenic stressors. 相似文献
72.
美国空气固定源排污许可证中关于监测的规定及启示 总被引:3,自引:2,他引:1
监测规定是美国空气固定源运行排污许可证中的核心内容。基于"个案管理"原则,每个运行许可证中的各个产排污单元分别执行不同的监测规定。获得"连续"的监测数据需足够判定固定源排放是否合规,且成本有效。"固定源制定和提交监测方案-管理机关审核-监测方案载入排污许可证中-依方案监测-数据处理-排污许可证守法报告-管理机关合规监测和评估"的系统化监测程序,使得固定源监测更具可操作性,监测数据更规范。建议中国排污许可证制度中建立类似的监测规定。 相似文献
73.
氙灯老化试验目前是众多汽车企业必检项目之一,汽车内外饰件用到的非金属材料有很多,如涂料、塑料、纤维织物、橡胶、皮革及装饰木纹件等等,并且形状多样,如何让氙灯试验更加准确,重复性更好,这对试验样品有严格的要求。 相似文献
74.
In many cooperatively breeding species, dominant females suppress reproduction in subordinates. Although it is commonly assumed
that aggression from dominant females plays a role in reproductive suppression, little is known about the distribution of
aggressive interactions. Here, we investigate the distribution of aggressive and submissive interactions among female meerkats
(Suricata suricatta). In this species, dominant females produce more than 80% of the litters, but older subordinates occasionally breed. Dominant
females commonly kill the pups of subordinates and usually evict older female subordinates from the group 1–3 weeks before
the birth of the dominant female's litter. The aggression frequency of the dominant female toward subordinates and the submission
frequency that each subordinate female showed to the dominant female increased as the age of the subordinate female increased
and as the birth of the dominant female's pups approached. Moreover, as birth approached, both of these behaviors intensified
more quickly between the dominant female and older subordinates than between the dominant female and younger subordinates.
The aggression frequency of the dominant female toward each subordinate female predicted whether that subordinate female was
evicted from the group; the submission frequency by each subordinate female predicted the timing of their eviction during
the pregnancy period of the dominant female. These results support the idea that conflict between dominant and subordinate
females increases with the age of subordinates and, since older subordinate females are most likely to reproduce, suggest
that dominant females may less easily control reproductive attempts by older subordinate females. 相似文献
75.
Tae Won Kim Kotaro Sakamoto Yasuhisa Henmi Jae C. Choe 《Behavioral ecology and sociobiology》2008,62(7):1139-1147
For males, courting and foraging are often behavioral alternatives, which take time and consume energy. When males have a
possibility of mating with receptive females, there may be a behavioral trade-off between courtship and feeding; the outcome
of which may be affected by male physiological condition and food availability. Although many mathematical models and empirical
studies suggest that the expression of male courtship signals are condition-dependent, decisions about courtship and mating
strategies in relation to food availability have not attracted much attention. In this study, we tested whether daily changes
in food availability affect males’ decisions about whether to court. We conducted experiments with the fiddler crab Uca lactea by providing males with additional food every other day. In food-supplemented enclosures, males did not increase courtship
activity on the days when food was supplemented. However, they built more courtship structures (semidomes) and waved more
on the days when they were not given additional food. Male size had a strong influence on the number of days the males courted.
We also tested whether the frequency of surface mating, as an alternative reproductive tactic, decreased when food was supplemented.
Contrary to our expectation, the number of males that exhibited the surface-mating tactic increased when food was supplemented
whereas the number of mate-searching females did not change. Our findings in this field study suggest that reproductive decisions
by male fiddler crabs are affected by fluctuating food availability and present body condition, and the alternative mating
tactic of this species may be more frequently used by males under good condition. 相似文献
76.
Pierre-Paul Bitton Russell D. Dawson Courtney L. Ochs 《Behavioral ecology and sociobiology》2008,62(10):1543-1550
Elaborate ornamental plumage has been associated with various measures of individual quality in many species of birds. Male
plumage characteristics, which have been relatively well studied, have been shown to reflect past reproductive investment,
as well as the potential for reproductive investment in the current breeding attempt. In contrast, the signalling functions
of female traits remain largely unexplored. In this study, we investigated the relationship between plumage attributes of
breeding adult tree swallows and past reproductive investment, current reproductive investment and social mate pairing strategy.
Both males and older females possess metallic green to metallic blue iridescent plumage on their dorsal surface, making this
a suitable species for this type of investigation. We did not find any effects of past reproductive investment and success
on the plumage attributes of returning breeders. In contrast, female plumage hue covaried with fledging success, and female
plumage brightness was positively associated with mean clutch egg mass. In addition, we found that social pairs mated assortatively
with respect to plumage brightness. We argue that since plumage characteristics vary with age in both male and female tree
swallows, plumage attributes in this species are indicative of breeding experience and may be honest signals of quality. Positive
assortative pairing could be the result of mutual mate choice or intra-sexual competition for nest sites by both males and
females. 相似文献
77.
Although assortative mating is widespread among long-lived monogamous birds, the underlying mechanisms still remain unclear
in many species. In this study, we analysed assortative mating by age and body mass in the common tern Sterna hirundo with special regard to mate choice decisions of newly paired birds. To assess whether assortative mating by age is an active
decision involving either homotypic or directional preferences or rather a passive process due to restricted availability
of potential mates, we analysed the influence of age-dependent arrival date and cohort size. Furthermore, we looked for direct
benefits in terms of reproductive success. Common terns mated assortatively by age and arrival date but not by body mass at
arrival. Assortative mating by age was age dependent and was detected mainly in younger birds, whereas birds older than 8 years
rather re-paired with younger ones. The availability of same-aged mates was restricted by cohort size and arrival date. We
found no general evidence for better reproductive performance of same-aged pairs. Instead, relative reproductive success was
related to own age and the relative age of mate: It should be advantageous for any bird to acquire an old mate; hence, assortative
mating by age seems to be beneficial only for old terns but not for young ones. Age-assortative mating in common terns occurred
by both passive and active processes, which are not mutually exclusive. Our results do not indicate a homotypic but a directional
preference and support the theory that high-quality (older/experienced) individuals tend to mate assortatively if same-aged
mates are available, which leaves low-quality (young/inexperienced) individuals to mate among themselves. 相似文献
78.
胡亚楠 《中国个体防护装备》2011,(5)
本文主要介绍了ASTM F 2669-2009《施用农药人员用防护服性能标准》的分级和检测要求、防护服材料性能要求、材料的抗渗透性指标等,并就施药人员的安全与防护以及完善防护服标准体系提出建议,以为我国广大相关领域人员了解标准和应用标准提供帮助。 相似文献
79.
贺毅 《中国个体防护装备》2011,(6):19-21
本文主要介绍了新版ISO 23269-4:2010《船舶和海洋技术-船用氧气呼吸器-第4部分:符合IMO的IBC和IGC法规要求的紧急逃生用自给式氧气呼吸器》国际标准的制定背景、内容以及基本性能试验和要求,以对我国采用该国际标准提供帮助。 相似文献
80.
Ole-Gunnar Støen Andreas Zedrosser Per Wegge Jon E. Swenson 《Behavioral ecology and sociobiology》2006,61(1):1-8
Reproductive suppression through behavioral or physiological means is common in group-living and cooperative breeding mammals, but to our knowledge it has not been shown in wild large carnivores other than those with a clear form of social organization. Brown bear (Ursus arctos) females form matrilinear assemblages with related females using a common and largely exclusive area. Behavioral reproductive suppression might develop due to a hierarchical system among females within a matrilinear assemblage or due to inbreeding avoidance, because male brown bears can overlap with their daughters. We tested whether natal dispersal influenced the age of primiparity. We predicted that emigrant females, geographically removed from maternal or paternal influence, would reproduce earlier than philopatric females. The average age of primiparity was 4.3 years in females that dispersed outside their mother’s home range (n=8) and 5.2 years in philopatric females (n=10). Only the overlap with the mother’s home range, and not body size, body mass, growth, local population density, or overlap with the father’s home range, had a significant influence on the age of primiparity. The ultimate role of reproductive suppression for brown bears is likely to avoid inbreeding or to minimize resource competition. Due to the low risk of inbreeding and frequent exposure of young females to unrelated males, we conclude that resource competition within female hierarchies causes reproductive suppression in young females. 相似文献