Detection of feeding behaviour in common carp Cyprinus carpio by using an acceleration data logger to identify mandibular movement

Miniaturized acceleration data loggers were attached to the lower mandible of common carp Cyprinus carpio to remotely identify feeding behaviour. Whether the acceleration signal could distinguish the quantity and quality of food was also investigated. The frequency and amplitude of the lower mandible stroke, calculated from surging acceleration determined by continuous wavelet transformation, significantly increased during the feeding period compared to that during the non-feeding period. These characteristic movement patterns were maintained for mean ±s.e. 187·3 ± 38·2 s when the fish were fed a single item of food and for mean ±s.e. 419·3 ± 28·6 s when they consumed multiple items. The dominant cycle and amplitude calculated according to feeding event duration, however, did not differ significantly between the two types of diets the fish consumed. Surging acceleration could detect mean ±s.e. 89·8 ± 13·5% of feeding events, although the false detection rate was mean ±s.e. 25·9 ± 10·9%. The results indicate that the mandible acceleration measurement method could be utilized to detect and record the feeding events in fishes that use a suction feeding mode similar to C. carpio.     

入侵种西花蓟马与其它昆虫的种间竞争

西花蓟马Frankliniella occidentalis作为一种重要的入侵害虫,在全球范围的入侵过程中,为获取更多资源以建立自己的种群,势必会和处于同一营养级的昆虫发生种间竞争。本文对近年来有关西花蓟马与其它种蓟马、粉虱及叶螨等昆虫种间竞争的研究进行了综述,分析了温度、CO 2、寄主植物、农药和天敌等主要因素在竞争取代中的作用,并对今后的研究方向以及种间竞争的研究方法进行了讨论,以期为揭示西花蓟马在我国的种群动态和变化规律奠定基础。     

Population ecology, vertical migration and feeding of the Ponto-Caspian invader Hemimysis anomala in a gravel-pit lake connected to the River Rhine

1. The Ponto‐Caspian invader, Hemimysis anomala, was recently found in large numbers in a gravel‐pit lake connected to the Lower Rhine. Mysids were sampled with Perspex traps between September 2002 and April 2003 to study the population dynamics, vertical migration and feeding. 2. The abundance (as catch per unit effort, CPUE) of H. anomala declined from 270 individuals (ind.) trap^?1 (4 h)^?1 in December to below 4 ind. trap^?1 (4 h)^?1 in April. Average lengths ranged from 4.9 mm in autumn to 9.9 mm in March. The length–weight relationship of virgin females changed throughout the sampling period, from a size‐corrected wet weight of 5.1 mg in September to 16.6 mg in April for a female of 7.8 mm. 3. Successive monthly samples taken over 24 h revealed that H. anomala preferred the surface at twilight and night. During dawn the mysids migrated to the middle and bottom layers and were hardly found during day. Diel vertical migration clearly depends on the proximate factor light. 4. Stomach analyses revealed that larger H. anomala preferred zooplankton, whereas small individuals fed more on phytoplankton. The seasonal comparison showed an increasing percentage of zooplankton with increasing length. The proportion of zooplankton in the stomachs of large H. anomala individuals was highest during night and lowest during day. 5. The results suggest that H. anomala may become an important link between primary/secondary production and higher trophic levels in the food web of its new environments at the Lower Rhine.     

Potential food resources available to malleefowl Leipoa ocellata in marginal mallee lands during drought

Abstract Prime mallee lands that once supported high densities of malleefowl, Leipoa ocellata in New South Wales have been extensively cleared for agriculture. Malleefowl are now restricted largely to more and habitat. Given the added competition from introduced herbivores, there is concern that these marginal habitats may not contain sufficient food resources to support viable populations of malleefowl, particularly in times of drought. An opportunistic feeding strategy and omnivorous diet enable malleefowl to exploit a diverse array of food items. Vegetative and invertebrate food resources available to malleefowl in marginal mallee lands were monitored over a period of 1 year during drought. Food resources were varied, transient and patchily distributed. Composition and abundance fluctuated considerably, but potential food was never entirely absent. Despite the prevailing drought, food was obtainable throughout the year provided malleefowl adapted to the fluctuating availability of each of the various potential food resources. Reduced food resources in marginal habitat is not implicated as a major factor in the demise of the malleefowl. Food was most abundant between August and November, inclusive, due largely to the abundance of herbs, the diverse supply of buds, flowers and fruit on perennial shrubs, and the sporadic proliferation of cockroaches. Food availability was least, and therefore most critical, during February, March and June. The most favourable time of the year, in terms of available food resources, for the release of captive-bred individuals was during spring, around September.     

生物入侵对鸟类的生态影响

生物入侵是全球生物多样性面临的最主要威胁之一, 入侵种在改变入侵地环境的同时也使当地的生物受到极大影响。鸟类在生态系统中处于较高的营养级, 生态系统中任何一个环节的变化都可能对鸟类造成一定的影响。本文回顾了哺乳动物、鸟类、无脊椎动物和植物等不同生物类群的入侵对本地鸟类生态影响方面的研究进展。外来生物对鸟类的影响主要表现在以下几方面: (1)外来哺乳动物对成鸟、幼鸟或鸟卵的捕食作用; (2)外来鸟类与本地鸟类竞争栖息地和食物资源, 与当地的近缘种杂交而造成基因流失; (3)外来无脊椎动物改变本地鸟类的栖息环境和食物状况, 甚至直接捕食本地鸟类; (4)外来植物入侵改变入侵地的植物群落组成和结构, 造成本地鸟类的栖息地丧失或破碎化, 并通过改变入侵地生态系统的食物链结构而对高营养级的鸟类产生影响。最后, 作者还提出了该领域有待解决的问题和今后可能的研究方向。     

A novel interference behaviour: invasive wasps remove ants from resources and drop them from a height

This study reports a novel form of interference behaviour between the invasive wasp Vespula vulgaris and the New Zealand native ant Prolasius advenus. By videotaping interactions at bait stations, we found that wasps commonly remove ant competitors from food resources by picking up the workers in their mandibles, flying backward and dropping them unharmed some distance from the food. Both the frequency and the efficiency of the wasp behaviour significantly increased with the abundance of ant competitors. Ant removals were the most common interference events initiated by wasps when ants were numerous, while intraspecific conflicts among wasps were prominent when few ants were present. The 'ant-dropping' behaviour emphasizes how asymmetry in body sizes between competitors can lead to a pronounced form of interference, related to asymmetric locomotion modes.     

Feeding performance of Lake Victoria rock cichlids: testing predictions from morphology

Cichlid fishes that seem specialized phenotypically to exploit certain resources often act as generalists in the field. It is attempted to resolve this paradox by measuring feeding performance. There are two ways of feeding, namely suction feeding and biting, that set conflicitng demands on the anatomy. Rock-dwelling cichlids of the genus Neochromis are specialized biters, feeding largely on filamentous algae and benthic organisms. Pundamilia nyererei is one of the most specialized suction feeders among rock cichlids, its diet being zooplankton and insect larvae. A morphological analysis showed that the three Neochromis species are better adapted anatomically to biting than P. nyererei , while P. nyererei is better adapted to suction feeding. Feeding performance was tested on algal substitute and Chaoborus larvae, representing filamentous algae and zooplankton, respectively. As expected the Neochromis species fed most efficiently on algal substitute, N. rufocaudalis and N. omnicaeruleus taking per bite 2.6 times as much as P. nyererei , and N. greenwoodi 1.7 times. Unexpectedly, the species examined were all well able to collect Chaoborus. P. nyererei collected only 1.2 times as many larvae per suction act as the Neochromis species. Analysis of the stomach contents showed that P. nyererei punctured, or lacerated, the larvae with the pharyngeal jaws, while the Neochromis species swallowed them mostly intact. Thus, feeding on Chaoborus , P. nyererei may be optimizing energy gain and not intake rate.     

不同类型人类活动干扰对河岸带外来植物群落的影响——以北京永定河为例

强烈的人类活动对自然生境的扰动促进了外来植物侵入河岸带,但不同类型的人类活动干扰对外来植物的影响有所不同。按照不同人类活动干扰类型设置了山峡段、平原段和城市段,通过比较河段间河岸带外来植物群落特征的差异,探讨不同人类活动干扰类型对河岸带外来植物群落的影响。结果表明:(1)永定河河岸带共有维管束植物27科72属101种,外来植物13科28属29种。外来种比例高达28.7%,其中82.4%的国外外来种来自美洲和亚洲。(2)不同河段间的外来植物群落的物种构成和优势度呈现出显著性差异。外来种比例由山峡段的20.9%,上升至平原段和城市段的30.2%和25.5%;而优势度由12.1%,分别上升至13.4%和17.5%。(3)不同河段间的外来植物群落生活型结构有显著性差异。多年生草本植物在山峡段比例最高,达到66.7%,在平原段和城市段较低,分别为46.2%和30.8%;而一年生草本植物在城市段比例最高,达到69.2%,在平原段和山峡段较低,分别为53.8%和33.3%。(4)平原段属于农业干扰类型,其河岸带外来植物主要以农业类杂草为主,如禾本科的假稻(Leersia japonica)和菊科的钻叶紫菀(Aster subulatu);城市段是城市干扰类型,外来植物中入侵种比例和优势度较高,典型入侵种为反枝苋(Amaranthus retroflexus)和牛筋草(Eleusine indica)等。北京永定河不同河段河岸带外来植物的种类构成特点,反映了河岸带外来植物受快速城市化、农业活动等不同人类活动干扰的影响呈逐渐扩大的趋势。