Predicting the unexpected: using a qualitative model of a New Zealand dryland ecosystem to anticipate pest management outcomes

Pest management is expensive and there is often uncertainty about the benefits for the resources being protected. There can also be unintended consequences for other parts of the ecosystem, especially in complex food webs. In making decisions managers generally have to rely on qualitative information collected in a piecemeal fashion. A method to assist decision making is a qualitative modelling approach using fuzzy cognitive maps, a directed graphical model related to neural networks that can take account of interactions between pests and conservation assets in complex food webs. Using all available information on relationships between native and exotic resources and consumers, we generated hypotheses about potential consequences of single‐species and multi‐species pest control on the long‐term equilibrium abundances of other biotic components of an ecosystem. We applied the model to a dryland ecosystem in New Zealand because we had good information on its trophic structure, but the information on the strength of species interactions was imprecise. Our model suggested that pest control is unlikely to significantly boost native invertebrates and lizards in this ecosystem, suggesting that other forms of management may be required for these groups. Most of the pest control regimes tested resulted in greater abundances of at least one other pest species, which could potentially lead to other management problems. Some of the predictions were unexpected, such as more birds resulting from possum and mouse control. We also modelled the effects of an increase in invasive rabbits, which led to unexpected declines of stoats, weasels, mice and possums. These unexpected outcomes resulted from complex indirect pathways in the food web. Fuzzy cognitive maps allow rapid construction of prototype models of complex food webs using a wide range of data and expert opinion. Their utility lies in providing direction for future monitoring efforts and generating hypotheses that can be tested with field experiments.     

Grazing by the intertidal fish Anoplarchus purpurescens upon a distasteful polychaete worm

Synopsis Cirratulid worms are common inhabitants of the central California rocky intertidal zone and appear to offer a potentially rich source of food for intertidal fishes. However, analyses of stomach contents revealed that they do not appear in the diets of the commonest intertidal fishes. Apparently only one species, the eel blenny Anoplarchus purpurescens, feeds on cirratulids in significant amounts.Feeding experiments employing local intertidal fishes showed that the common intertidal cirratulid, Cirriformia luxuriosa, is distasteful to most of the fishes. Only two species ate its tentacles, and only A. purpurescens consistently ate large quantities. We propose that C. luxuriosa possesses a predation-deterring chemical similar to that reported in C. spirabrancha, although A. purpurescens apparently has been able to circumvent this anti-predator mechanism.The ability of A. purpurescens to eat Cirriformia tentacles allows it to tap a seemingly little-used food source, and thus may decrease competition between A. purpurescens and other intertidal fishes. This feeding relationship also represents a possible example of coevolution between a predator and its prey.     

Trophic Structure of One Deep-sea Benthic Fish Community in the Eastern Canadian Arctic: Application of Food, Parasites and Multivariate Analysis

Synopsis As new arctic marine fisheries develop there is need for a comprehensive ecosystem approach to long-term management. This approach recognizes the importance of community interactions such as food web structure and trophic patterns. We determined whether hierarchical clustering (guild formation) is an effective method of trophic evaluation in deep-sea Artic fish communities using stomach content and parasite data with size class, and evaluated the application of endohelminth communities (parasite species transmitted in the food) as indicators of trophic status. Cluster analysis using food group abundance with size class of fish revealed the presence of 11 guilds within the community, however the same analysis using parasite data showed little correlation between food and parasites. Redundancy analysis (RDA) within the 11 guilds also revealed no significant correlations between food group and parasite abundance suggesting that this type of ordination is not suited for environments containing mainly generalist feeders. RDA of individual taxa without a priori guild designation found that taxa in benthic deep-sea communities are defined by their ability to exploit prey species in more than one habitat zone. Benthic fish species were significantly correlated with benthic food groups and parasites that utilize benthic intermediate hosts whereas benthopelagic–pelagic species fed on a higher diversity of prey species and were infected by a larger number of non-host specific parasites. Eigenanalysis and Monte Carlo results showed that parasites and food groups are highly correlated, indicating that parasite community analysis is an effective tool for predicting feeding strategies in Arctic marine environments. It also suggests that in most cases endoparasite infections alone could be used for trophic evaluation in the absence of stomach content data.     

北京城市化进程中家庭食物碳消费动态

不可持续的家庭消费是造成全球环境问题的主要原因,食物碳消费研究是促进可持续家庭消费的重要内容。基于政府宏观统计数据,分析北京城市化进程中城市家庭食物碳消费的变化趋势和影响因素。结果表明,与1979年相比,1999年北京城市家庭人均及户均食物消费量分别减少了15.2%和38.6%,而食物碳消费总量增加了28.5%,食物碳消费结构由“以粮食为主”转变成“以粮食和肉类为主”。城市化进程中,以1993年为界,家庭食物人均及户均碳消费量均由明显减少趋势转变为明显增长趋势,变化的主要原因由“食物消费结构变化引起的人均谷物类碳消费量的减少”转变为“人均食物消费量增加引起的人均肉类碳消费量的增加”。北京城市家庭已基本完成食物消费结构的转变,人均食物消费量仍继续增加。GDP指数是影响人均食物碳消费量的主要经济因素,经济的继续增长可能带来人均食物碳消费量的增加,北京城市家庭食物碳消费尚未达到稳定状态。     

东方田鼠种群扩散及活动对外部因子的反应格局

在野外围栏条件下,采用2×2×2析因实验,测定外部因子食物、捕食,以及同域分布物种黑线姬鼠的种间竞争对东方田鼠扩散和活动距离的独立作用及其交互作用的效应。研究结果表明,在所有的扩散个体中,幼体扩散的比例为71.0%。雄体扩散的比例为80.5%。东方田鼠扩散的趋势与其种群密度及补充量的变动一致。食物对扩散具有显著独立作用;捕食对扩散的作用接近显著;种间竞争对扩散的直接效应不显著;食物、捕食与种间竞争交互作用对扩散的效应亦不显著。在诱捕期内雄性的长距离活动比例及其诱捕期间长距离活动比例均显著大于诱捕期内雌性及其诱捕期间的长距离活动比例。不同处理种群间,仅雄体在诱捕期间的长距离活动比例具有显著差异;食物对雄体的长距离活动具有直接和间接(通过密度)的效应;而预防捕食者和竞争物种对不同处理种群雄体的长距离活动则无一致的效应。     

The food web in the lower part of the Seine estuary: a synthesis of existing knowledge

The Seine estuary illustrates the alterations to estuaries due to human activities heavy releases of pollutants of various origins and significant morphological changes beginning in the middle of the 19th century. The intertidal mudflat surface has been seriously reduced (< 30km²) since the channels of the Seine River came under management. While the role of the Seine estuary in the dynamics of the eastern English Channel ecosystem is recognized as important, the biological characteristics of the estuary remained relatively unknown until the 1990s. Biological diversity was progressively impoverished from the polyhaline zone to the oligohaline zone. In spite of a heavily contaminated environment, the macrobenthic and planktonic fauna of the Seine estuary remains similar to those of other northeastern Atlantic estuaries. The fauna exhibit clear contrasts between areas with very high abundance and others with very low abundance. The pelagic fauna, especially the copepod Eurytemora affinisand the shrimp Palaemon longirostris, are more abundant in the Seine estuary than in other estuaries. Diversified and abundant, Abra alba-Pectinaria koreni and Macoma balthica benthic communities occur, respectively, in the outer and inner parts of the estuary. In subtidal flats, benthic fauna is especially poor in terms of specific richness, abundance and biomass. Paradoxically, considering the high abundance of prey, fish are particularly scarce. Two food webs have been identified. In the oligohaline zone, where turbidity is maximum, the food web is exclusively planktonic, due to dredging that prevented benthic fauna from settling. In the polyhaline zone, fish populations that feed particularly on benthic fauna benefit from low turbidity and high oxygen concentrations. So, in spite of heavy organic and metallic contamination and human activities, the Seine estuary remains a highly productive ecosystem, which provides a nursery for marine fish and feeding grounds for migratory birds. A global management plan appears to be necessary in order to guarantee that the Seine estuary continues to function as it currently does.     

Mycobacterium avium Subspecies Paratuberculosis in the Inflamed Gut Tissues of Patients with Crohn’s Disease in China and its Potential Relationship to the Consumption of Cow’s Milk: A Preliminary Study

Summary Mycobacterium avium subspecies paratuberculosis infection in domestic livestock is widespread in many countries throughout the world. Studies in Europe and the USA show that M. avium subspecies paratuberculosis can be cultured from retail pasteurized cow’s milk and that these organisms are being transmitted to humans by this route. Most people with chronic inflammation of the intestine of the Crohn’s disease type are infected with these chronic enteric pathogens. The production and consumption of cow’s milk has increased in China and so also has the incidence of Crohn’s disease. The present preliminary investigation was carried out to determine whether M. avium subspecies paratuberculosis is present in the intestinal tissues of Chinese patients with Crohn’s disease who have never left China. Archival paraffin-embedded surgical pathology blocks from patients having surgery for Crohn’s disease (CD) or for cancer (nIBD) in China were studied. M. avium subspecies paratuberculosis was detected by nested IS900 PCR with Southern blotting and amplicon sequencing. The intestinal tissues of 9 of 13 (69.2%) CD patients and 2 of 14 (14.3%) nIBD patients were IS900 PCR positive (P = 0.0063; odds ratio = 13.5). These initial studies suggest that people in China are exposed to M. avium subspecies paratuberculosis and that as in other countries, the infection is significantly associated with Crohn’s disease. M. avium subspecies paratuberculosis in dairy herds and retail milk in China needs to be investigated.     

铅色水蛇Enhydris plumbea(Boie, 1827) 的生物学初探(蛇亚目:游蛇科:仰鼻蛇亚科)

根据野外观察和解剖标本, 本文报道蛇亚目、游蛇科、水游蛇亚科中国南方常见优势种铅色水蛇的生物学研究初步结果.1.长度112号雄蛇全长范围286 ～466 mm,151号雌蛇全长范围306～504 mm.海南陵水103号雄蛇最大全长358+54=412 mm,137号雌蛇最大全长443+61=504 mm.2.鳞片的变异根据299号标本观察,数量恒定无变异的鳞片有吻鳞(1), 鼻间鳞 (1), 前额鳞 (2), 额鳞 (1), 顶鳞 (2), 鼻鳞 (每侧1), 颊鳞 (每侧1), 眶上鳞(每侧1), 前颞鳞 (每侧1), 颏鳞 (1), 颔片 (2 对), 背鳞 (19-19-17 行), 肛前鳞 (完整);根据鳞片有变异的67号标本观察, 可出现变异鳞片的变异范围及其频率眶前鳞1(1→2,4.5%),眶后鳞2(2→1,3.0%),后颞鳞2(2→1,1.5%),上唇鳞3-2-3(3-1-4,0.75%),下唇鳞10(9,0.75%;11,2.25%);腹鳞与尾下鳞则绝对有变异腹鳞雄性112号变异幅度124～136 (平均 128.2), 雌性151号变异幅度123～132 (平均 126.1),尾下鳞雄性107号变异幅度36～41 (平均 39.7)对,雌性149号变异幅度31～36 (平均 33.7)对.3.两代之间变异的消失和出现两例母蛇的右侧眶前鳞均变异为2,她们的全部仔蛇21号均正常为1;一例母蛇的下唇鳞为正常的10枚,而她的仔蛇6号中有两号分别有一侧或两侧变异为9.4.垂直分布范围沿海低地到海拔985 m.5.栖息环境各种水域,以静水水域为主,在海南陵水县吊罗山大里乡以灌水后的稻田为主,极少数发现在静水水域或流动缓慢的灌溉渠内.6.摄食和食性每年4月开始摄食,6月为摄食高峰,9月停止;食物以小形蛙类和蝌蚪为主,其次为小鱼.7.繁殖习性二级性征主要反映在雄性尾的比例较长,尾下鳞的数目相应较多;二级性比(出生时的性比)接近11,三级性比在居群较大的情况下也约为11,而在居群较小的情况下统计约为0.51;雌性性成熟期(以开始产仔为依据)全长都在350 mm以上;解剖28号孕雌得知输卵管卵数3～12(平均6.3)枚;卵在母体内发育进程解剖41号成熟雌性得知4月卵尚未发育,5月及6月处于发育中或晚期、产仔或已产出,7月基本都已产毕;统计两窝21仔得知初产出仔蛇全长127～139 mm,母蛇体长大者其仔蛇亦较长;统计同窝9仔得知初生仔蛇重量2.4～2.5 g,平均2.47 g.本文是作者早期未发表的工作,现整理供对蛇类有兴趣的青年同行参考.本研究所用全部标本(包括3号雌蛇及其刚产出的仔蛇) 均保存在中国科学院成都生物研究所两栖爬行动物标本馆.     

Energy Metabolic Profile of Mice after Chronic Activation of Central NPY Y1, Y2, or Y5 Receptors**

Objective: Neuropeptide Y (NPY), a 36‐amino acid peptide with orexigenic properties, is expressed abundantly in the central nervous system and binds to several NPY receptor subtypes. This study examines the roles of the NPY Y1, Y2, and Y5 receptor(s) in energy homeostasis. Research Methods and Procedures: We administered intracerebroventricular NPY (3 μg/d) or selective peptide agonists for the Y1, Y2, and Y5 receptor subtypes to C57Bl/6 mice for 6 days by mini‐osmotic pumps to assess the role of each receptor subtype in NPY‐induced obesity. Energy expenditure (EE) and respiratory quotient (RQ) were studied using indirect calorimetry. Adiposity was measured by DXA scanning and fat pad dissection. Insulin sensitivity was tested by whole‐blood glucose measurement after an insulin challenge. Results: Central administration of the selective Y1 agonist, Y5 agonist, or NPY for 6 days in mice significantly increased body weight, adiposity, and RQ, with significant hyperphagia in the Y5 agonist‐ and NPY‐treated groups but not in the Y1 agonist‐treated group. The NPY, Y1, or Y5 agonist‐treated mice had little change in total EE during ad libitum and pair‐feeding conditions. Conversely, selective activation of the Y2 receptor reduced feeding and resulted in a significant, but transient, weight loss. Discussion: Central activation of both Y1 and Y5 receptors increases RQ and adiposity, whereas only Y5 receptor activation reduces energy expended per energy ingested. Selective activation of Y2 autoreceptors leads to hypophagia and transient weight loss, with little effect on total EE. Our study indicates that all three NPY receptor subtypes may play a role in regulating energy homeostasis in mice.     

Scaling up keystone effects from simple to complex ecological networks

Predicting the consequences of species loss requires extending our traditional understanding of simpler dynamic systems of few interacting species to the more complex ecological networks found in natural ecosystems. Especially important is the scaling up of our limited understanding of how and under what conditions loss of ‘keystone’ species causes large declines of many other species. Here we explore how these keystone effects vary among simulations progressively scaled up from simple to more complex systems. Simpler simulations of four to seven interacting species suggest that species up to four links away can strongly alter keystone effects and make the consequences of keystone loss potentially indeterminate in more realistically complex communities. Instead of indeterminacy, we find that more complex networks of up to 32 species generally buffer distant influences such that variation in keystone effects is well predicted by surprisingly local ‘top‐down’, ‘bottom‐up’, and ‘horizontal‘ constraints acting within two links of the keystone subsystem. These results demonstrate that: (1) strong suppression of the competitive dominant by the keystone may only weakly affect subordinate competitors; (2) the community context of the target species determines whether strong keystone effects are realized; (3) simple, measurable, and local attributes of complex communities may explain much of the empirically observed variation in keystone effects; and (4) increasing network complexity per se does not inherently make the prediction of strong keystone effects more complicated.