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121.
Invasions by alien species are one of the major threats to the native environment. There are multifold attempts to counter alien species, but limited resources for mitigation or eradication programmes makes prioritisation indispensable. We used the generic impact scoring system to assess the impact of alien fish species in Europe. It prioritises species, but also offers the possibility to compare the impact of alien invasive species between different taxonomic groups. For alien fish in Europe, we compiled a list of 40 established species. By literature research, we assessed the environmental impact (through herbivory, predation, competition, disease transmission, hybridisation and ecosystem alteration) and economic impact (on agriculture, animal production, forestry, human infrastructure, human health and human social life) of each species. The goldfish/gibel complex Carassius auratus/C. gibelio scored the highest impact points, followed by the grass carp Ctenopharyngodon idella and the topmouth gudgeon Pseudorasbora parva. According to our analyses, alien fish species have the strongest impact on the environment through predation, followed by competition with native species. Besides negatively affecting animal production (mainly in aquaculture), alien fish have no pronounced economic impact. At the species level, C. auratus/C. gibelio show similar impact scores to the worst alien mammals in Europe. This study indicates that the generic impact scoring system is useful to investigate the impact of alien fish, also allowing cross‐taxa comparisons. Our results are therefore of major relevance for stakeholders and decision‐makers involved in management and eradication of alien fish species.  相似文献   
122.
比较分离自温泉、淡水及土壤的捕食线虫真菌——少孢节丛孢(Arthrobotrys oligospora)的生长特性及捕食效力。通过测定三种生境少孢节丛孢在不同温度、p H及有氧和无氧条件下的生长率及其在最适培养条件下对线虫的捕食率,得出三种生境中少孢节丛孢的最适生长温度均为30℃,分离自温泉和土壤的少孢节丛孢最适p H分别为5.5~7.0和4.5~5.5,而淡水生境少孢节丛孢对不同p H具有广泛适应性;淡水和温泉生境少孢节丛孢对无氧环境有一定的耐受性,而土壤生境少孢节丛孢在无氧环境下生长率低至1.24 cm/5 d。三种生境的少孢节丛孢捕食效力没有显著性差异。  相似文献   
123.
Invertebrate weed seed predation is an important component of weed seed loss in agricultural fields. This study investigated the role of seed imbibition on the selection and consumption of the seeds of seven common agricultural weed species by Harpalus pensylvanicus De Geer, a granivorous carabid beetle (Coleoptera: Carabidae) that is found throughout North America. The volatile organic compounds released by ambient dry and imbibed weed seeds were quantified, and Y-tube bioassays were conducted to determine if H. pensylvanicus individuals responded to volatile compounds released from weed seeds. H. pensylvanicus individuals were found to consume higher masses of seeds for each weed species examined in imbibed versus ambient dry trials (P < 0.05). Larger seeded species had the greatest increase in mass consumption between dry seed and imbibed seed trials. The seeds from the seven weed species examined released carbon dioxide and ethylene when ambient dry and imbibed, but H. pensylvanicus adults were only able to detect weed seeds through olfaction when volatile release was highest as a result of imbibition. These results demonstrate that seed imbibition is important in determining seed detection and consumption by invertebrates and may affect seed banks in agricultural fields.  相似文献   
124.
温度和猎物密度对斜纹猫蛛捕食的影响   总被引:2,自引:0,他引:2  
斜纹猫蛛(Oxyopes sertatus)是茶园和农田生态系统中重要的捕食性天敌,为明确斜纹猫蛛对果蝇类害虫的控制能力,探讨不同温度(18、20、22、24、26、28℃)以及猎物密度(20、25、30、35、40头/50 cm3)下斜纹猫蛛对果蝇的捕食作用.结果表明,在试验温度下斜纹猫蛛捕食量与温度变化关系显著相关(P<0.05),且随温度升高而增加,并且在26、28℃时捕食较多,其平均捕食量为18.7~19.3头/50 cm3;恒定温度(23±1)℃下,斜纹猫蛛捕食果蝇数量与密度变化显著相关(P<0.05),且随密度增加而增多,并且在果蝇密度为35、40头/50 cm3时捕食量较多,该情况下平均捕食量为25.3~26.3头.  相似文献   
125.
江苏侧隆螽具有个体大,食量大,活动范围广,发生早,捕食作用时间长等特点,是马尾松毛虫的有效天敌之一。1984~1986年,在室内进行了捕食者对不同虫态(龄期),马尾松毛虫的功能反应,测定了捕食者个体间的相互干扰作用及其对功能反应的影响,并建立了参数方程,能在一定程度上描述螽斯对马尾松毛虫卵,幼小幼虫及老龄幼虫的捕食作用。  相似文献   
126.
ABSTRACT:   Prey fish selection by Far Eastern catfish and largemouth bass were examined using bluegill, Japanese dace and crucian carp as food fish. In both aquaria (1.2 m × 0.45 m) and ponds (2.8 m × 1.2 m), bluegill was not preyed on by catfish and bass more than dace and crucian carp. In aquaria, there was no significant difference in the consumption of dace and crucian carp between catfish and bass, but in ponds, catfish preyed on dace and crucian carp more and less than bass, respectively. In the case that only bluegill and catfish were introduced in ponds, catfish consumed 4–15 g of bluegill per day. The introduction of catfish into ponds and lakes for the purpose of eradicating bluegill is considered appropriate for areas with few native fish species.  相似文献   
127.
This review summarizes results of an extensive series of laboratory studies on the behavioural responses of early life stages of walleye pollock, Theragra chakogramma to key environmental factors including light, temperature, gravity, turbulence, food availability and predator presence. Experiments focused on vertical distribution of egg through 0-age stages, and social interactions of age-0 juveniles. Key factors were modified either singly or in concert to determine their direct and indirect influence on fish behaviour. The observed results suggest that the behaviour of individual fish depends on the integration of a continually changing hierarchy of both intrinsic and extrinsic factors, with the relative importance of a specific factor varying with ontogeny and over time and space. The broad range of responses displayed by early life stages suggests that behaviour plays an important role in determining the consequences of environmental variability on walleye pollock populations. In general, results from our laboratory experiments are consistent with patterns observed in field studies, supporting the efficacy of using experimental behavioural research to define some of the underlying mechanisms controlling distribution and survival in the field, and eventual recruitment to adult populations.  相似文献   
128.
An investigation was conducted to evaluate the annual variation in potential predation impact (PPI) on larval and juvenile Pseudopleuronectes yokohamae by Crangon uritai in Hakodate Bay using predator-prey size relationships. Laboratory experiments were designed to estimate the favorable prey size of C. uritai through back-calculation of body length (BL) of P. yokohamae from sagittal otolith diameter observed in the stomachs of C. uritai. The most favorable prey-predator size ratio (BL of P. yokohamae-total length (TL) of C. uritai) class was 0.15–0.19, and ranged from 0.12–0.31. There was a significant positive correlation between the BL increase of P. yokohamae and the bottom water temperature in the field, such that BLs stagnated during the cold year of 1999 from April to June, and increased during the warm year of 2002. In contrast, no significant correlation was found between the TL increase of C. uritai and the bottom water temperature. Moreover, there were no significant differences in the mean TL of C. uritai between months (April–June) or years (1998–2002). Variation of PPI depended on the relationships between the growth rates of P. yokohamae and bottom water temperature. Therefore, the warm year of 2002 resulted in higher potential predation impact (PPI≥20), and it was at least 20 days shorter than that of the cold year of 1999. These results suggest that increased bottom water temperature in the nursery area was one of the most important factors for cumulative predation loss.  相似文献   
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