贡嘎山亚高山森林生态系统草地亚系统小叶黄芪群落C循环研究

对贡嘎山亚高山森林生态系统草地亚系统冰川退缩9年迹地形成的小叶黄芪群落C循环进行了研究.根据植物固定的有机碳量、土壤有机碳储量和土壤CO2呼吸量,结合群落区域大气温度与土壤CO2排放关系, 研究得出贡嘎山亚高山森林生态草地亚系统小叶黄芪群落C循环周期为88年,是CO2循环的库.     

草地生态系统丛枝菌根真菌多样性研究进展

在描述丛枝菌根真菌在草地生态系统中的功能和作用的基础上,阐述了丛枝菌根真菌的多样性及影响其多样性的因素。指出丛枝菌根真菌是草地生态系统中不可忽视的组成部分,在草原退化植被的恢复重建中起重要作用。为草地生态恢复以及资源合理开发利用提供参考。     

甘南亚高山草甸弃耕演替过程中的物种多样性与生产力变化模式及相互关系研究

物种多样性与生产力之间的关系一直是生态学领域的研究热点。本研究通过采用空间代替时间的方法,对甘南亚高山草甸退耕时间为5,9,14,19,30年以及顶极群落样地的物种多样性、地上生物量进行调查、分析,探讨亚高山草甸弃耕地演替过程中物种多样性、生产力的变化规律及其相关关系,结果表明,1)弃耕地演替过程中,随着演替时间的推移,植物物种多样性先升后降,呈单峰曲线;2)在演替的前期生产力迅速提高,在第19年时达到最高的183.77g/m²,之后,生产力基本保持稳定;3)在演替过程中物种多样性与生产力呈正相关关系,在顶极群落中物种多样性与生产力之间无明显的相关关系;4)演替过程中群落中物种-多度分布模式由生态位优先占领型逐渐转变为对数-正态分布。     

Simulation analysis of the population dynamics of the mite, Psoroptes ovis, infesting sheep.

The pattern of population growth of the ectoparasitic mite, Psoroptes ovis (Acari: Psoroptidae), on its ovine host is considered through the development of a Leslie matrix-based, simulation model. The model is parameterised using experimental data in conjunction with reanalysis of published data. The model shows that on sheep P. ovis populations grow at a rate of approximately 11% per day and the population doubles every 6.3 days. Additional rates of adult mortality, in excess of 50% per day, need to be imposed to prevent population growth. The predictions of the model are tested by comparison of the expected numbers of mites with the numbers recorded in lesions either on naturally infested sheep where the date of infestation can be estimated or on one artificially infested animal, where the initial number of mites and date of infestation are known precisely. In both cases the observed number of mites in lesions relate closely to the numbers expected from the simulations. The model simulations do not support the concept of a 'lag' phase as distinct from the 'growth' phase in the changing pattern of mite abundance on an infested sheep and suggests that the observed pattern of growth is a natural function of an exponential increase in numbers. The development of such models and their use in explaining the demographic processes which drive mite population dynamics are discussed.     

Parasites in cultured and feral fish.

Parasites, causing little apparent damage in feral fish populations, may become causative agents of diseases of great importance in farmed fish, leading to pathological changes, decrease of fitness or reduction of the market value of fish. Despite considerable progress in fish parasitology in the last decades, major gaps still exist in the knowledge of taxonomy, biology, epizootiology and control of fish parasites, including such 'evergreens' as the ciliate Ichthyophthirius multifiliis, a causative agent of white spot disease, or proliferative kidney disease (PKD), one of the most economically damaging diseases in the rainbow trout industry which causative agent remain enigmatic. Besides long-recognized parasites, other potentially severe pathogens have appeared quite recently such as amphizoic amoebae, causative agents of amoebic gill disease (AGD), the monogenean Gyrodactylus salaris which has destroyed salmon populations in Norway, or sea lice, in particular Lepeophtheirus salmonis that endanger marine salmonids in some areas. Recent spreading of some parasites throughout the world (e.g. the cestode Bothriocephalus acheilognathi) has been facilitated through insufficient veterinary control during import of fish. Control of many important parasitic diseases is still far from being satisfactory and further research is needed. Use of chemotherapy has limitations and new effective, but environmentally safe drugs should be developed. A very promising area of future research seems to be studies on immunity in parasitic infections, use of molecular technology in diagnostics and development of new vaccines against the most pathogenic parasites.     

青藏高原高寒草甸生态系统土壤有机碳动态模拟研究

利用高寒草甸区植被、土壤和气候等资料,借助Century模型研究了青藏高原高寒草甸生态系统土壤有机碳的动态。以2003年7月-2005年7月逐月气象观测资料为输入变量,模拟了自然条件下高寒矮嵩草草甸0～20cm土壤微生物呼吸CO₂-C通量季节变化。模拟值与观测值进行的回归分析显示,二者具有较好的一致性(R²=0.89,P＜0.05)。土壤有机碳动态模拟表明:1)自然条件下高寒草甸土壤有机碳在经历了一个快速积累过程后,积累速率逐渐趋于缓和,最终达到并接近稳定状态。稳定状态下0～20cm土壤总有机碳库约7597.50～7694.10gC/m²。其中活性、缓性和惰性土壤有机碳组分占土壤总有机碳储量的2.80%,58.50%和38.70%。2)过去45年(1960-2005)高寒草甸土壤有机碳呈振幅较为稳定的波动变化,但这种变化主要是土壤有机碳各组分波动变化的结果。气候波动对土壤有机碳影响主要与温度变化引起的惰性土壤有机碳库的变化有关,二者呈显著负相关(r=-0.548,P＜0.01)。降水量对土壤有机碳及有机碳各组分的影响不显著。     

Parasites of free-ranging small canids and felids in the Bolivian Chaco.

Parasite surveys of free-ranging wildlife provide important information for monitoring population health. Between March 2001 and March 2003, we sampled 10 ocelots (Leopardus pardalis), eight Geoffroy's cats (Oncifelis geoffroyi), a jaguarundi (Herpailurus yaguarondi), five pampas foxes (Pseudalopex gymnocercus), and three crab-eating foxes (Cerdocyon thous) at three sites in the Bolivian Chaco. The objective of the study was to survey the parasite fauna of these carnivores and compare prevalence of parasites among the sites. The parasite community of these carnivores was diverse, with representatives from eight genera of nematodes, two families of cestodes, two protozoan species, and six arthropod species. Fecal parasites identified from 12 of the 13 felids and five of the six canids examined included Aelurostrongylus abstrusus, Ancylostoma tubaeforme, Uncinaria sp., Crenosoma sp., Toxocara cati, Spirurida, Capillaria aerophila, Spirometra sp., Taeniidae, and Cystoisospora sp. Four tick species, Amblyomma parvum, A. tigrinum, A. ovale, and A. cajennense, and two flea species, Pulex irritans and Delostichus phyllotis, were identified. Two crab-eating foxes had serologic evidence of heartworm disease (HWD). Antibodies against Toxoplasma gondii were found in 15 of 26 animals. Although HWD was found only in canids inside the national park, parasite prevalence did not appear to differ among sites, and no evidence was found of parasite spillover from domestic to wild carnivores.     

Parasites of Horses and Dogs in N.S.W

Abstract of paper read before the Veterinary Section of the Australasian Association for the Advancement of Science, Adelaide, August , 1924.     

Parasites of South African wildlife. XII. Helminths of Nyala, Tragelaphus angasii, in Natal.

The helminths of 77 nyala, Tragelaphus angasii, from 4 game reserves in Natal, were collected, counted and identified. Ten nematode species and 4 nematode genera, a trematode species and paramphistomes, and 2 cestode genera were recovered from the antelope. Of these, a Cooperia rotundispiculum race, Gaigeria pachyscelis, a Gongylonema sp., Haemonchus vegliai, Impalaia tuberculata, an Oesophagostomum sp., a Setaria sp., Trichostrongylus deflexus, Trichostrongylus falculatus, the larval stage of a Taenia sp., a Thysaniezia sp. and Schistosoma mattheei are new parasite records for this host. Individual nematode helminth burdens varied from 3 to 13 493 and the total mean nematode burden was 700. The mean burdens of nyala from Mkuzi were the largest and those from animals from the Umfolozi Game Reserve and the False Bay Park the smallest. Ostertagia harrisi was the most prevalent nematode, and it was also the most numerous in nyala from Umfolozi, Mkuzi and False Bay. A race of Cooperia rotundispiculum was the most numerous in nyala from Ndumu. No clear-cut trends in the seasonal abundance could be discerned for any of the worm species recovered in this study.     

Parasites of South African wildlife. IX. Helminths of kudu, Tragelaphus strepsiceros, in the eastern Cape Province

The helminths of 25 kudu, Tragelaphus strepsiceros, from 3 localities in the eastern Cape Province were collected, counted and identified. The majority of kudu harboured no worms, and the burdens of those infected were small. A race of Cooperia rotundispiculum, a Dictyocaulus sp., a Haemonchus sp., Nematodirus helvetianus and Ostertagia ostertagi were recovered. Two parasites, Nematodirus helvetianus and Ostertagia ostertagi can be added to the list of helminth parasites of kudu in South Africa.     

Serosurvey for Toxoplasma gondii in arctic foxes and possible sources of infection in the high Arctic of Svalbard

Samples (blood or tissue fluid) from 594 arctic foxes (Alopex lagopus), 390 Svalbard reindeer (Rangifer tarandus platyrhynchus), 361 sibling voles (Microtus rossiaemeridionalis), 17 walruses (Odobenus rosmarus), 149 barnacle geese (Branta leucopsis), 58 kittiwakes (Rissa tridactyla), and 27 glaucous gulls (Larus hyperboreus) from Svalbard and nearby waters were assayed for antibodies against Toxoplasma gondii using a direct agglutination test. The proportion of seropositive animals was 43% in arctic foxes, 7% in barnacle geese, and 6% (1 of 17) in walruses. There were no seropositive Svalbard reindeer, sibling voles, glaucous gulls, or kittiwakes. The prevalence in the arctic fox was relatively high compared to previous reports from canid populations. There are no wild felids in Svalbard and domestic cats are prohibited, and the absence of antibodies against T. gondii among the herbivorous Svalbard reindeer and voles indicates that transmission of the parasite by oocysts is not likely to be an important mechanism in the Svalbard ecosystem. Our results suggest that migratory birds, such as the barnacle goose, may be the most important vectors bringing the parasite to Svalbard. In addition to transmission through infected prey and carrion, the age-seroprevalence profile in the fox population suggests that their infection levels are enhanced by vertical transmission.     

Parasites of South African wildlife. IV. Helminths of kudu, Tragelaphus strepsiceros, in the Kruger National Park

During ongoing surveys of parasites of wild animals in the Kruger National Park, a total of 96 kudu. Tragelaphus strepsiceros, were culled in the southern part of the park at monthly intervals from April 1981 to March 1983. A single kudu was shot in the same area in November 1983. Two more kudu were obtained from Pafuri in the northern part of the Park during October 1981 and another from near Satara in the central part of the Park during October 1982. The helminths of all the kudu were collected and 2 trematode, 4 cestode and 18 nematode species recovered. Amongst the helminths recovered, Agriostomum gorgonis, Cooperia fuelleborni, Cooperia hungi, Cooperia yoshidai, Impalaia tuberculata, a Parabronema sp., a Setaria sp., Strongyloides papillosus, Trichostrongylus falculatus, Schistosoma mattheei, an Avitellina sp., Moniezia benedeni, and Echinococcus sp. larvae appear to be new records for kudu. Haemonchus vegliai, which has been considered a rare nematode, was present in many animals. An amended list of the parasites of kudu is included, and the seasonal abundance of the major nematode species discussed and graphically illustrated.     

Parasites of South African wildlife. VII. Helminths of suni, Neotragus moschatus, in Natal

The helminths of 4 suni, Neotragus moschatus, from the Tembe National Elephant Park, KwaZulu, Natal, were collected, counted and identified. Cooperia hungi, a race of Cooperia rotundispiculum, Haemonchus vegliai, Setaria cornuta, a Skrjabinema sp., Strongyloides papillosus, Trichostrongylus anomalus and Trichostrongylus deflexus are new parasite records for suni in Africa. Megacooperia woodfordi was recovered for the first time from South African antelope.     

Parasites of South African wildlife. VIII. Helminth and arthropod parasites of warthogs, Phacochoerus aethiopicus, in the eastern Transvaal

Helminth and arthropod parasites were collected from 41 warthogs, Phacochoerus aethiopicus, in the Hoedspruit Nature Reserve, eastern Transvaal. This reserve consists of a military base, which is a restricted area and is surrounded by a reserve, which is open to the public. Eleven nematode species, 1 or 2 cestode species and the larvae of 2 cestode species were recovered from the animals in the reserve, and 8 nematode species and 1 or 2 cestode species were recovered from those in the military base. Oesophagostomum spp. were generally most abundant in warthogs in the reserve during the cooler months of the year, while Probstmayria vivipara also occurred in peak numbers during the cooler months, with an additional peak in October and November 1988 in warthogs in the reserve and the base, respectively. No pattern of seasonal abundance could be determined for the other helminth species. The warthogs also harboured 8 ixodid and 1 argasid tick species, 3 flea species and 1 louse species. Adult and immature Haematopinus phacochoeri were most numerous during August and September, and the largest numbers of adult Rhipicephalus simus were present from December to April.     

Parasitic forms of a myxosporean in the kidney of the arctic lamprey, Lampetra japonica: an ultrastructural study

We found frequent and unique parasitism by an unidentified myxosporean in the kidney of the arctic lamprey, Lampetra japonica, living in Japan. Trophozoites (pseudoplasmodia with or without sporoblasts) existed predominantly in the lumina of proximal urinary tubules, but were rarely found in any other regions of the kidney. Since no mature spores were produced in the trophozoites, exact identification of the species was impossible. Two parasitic forms were recognized in proximal urinary tubules: one adhering to the epithelial cells of renal tubules, and the other free-floating in the lumina of tubules. Ultrastructurally, the attaching trophozoites developed microvilli-like projections towards the apical surface of epithelial cells and vigorously interdigitated with microvilli of the brush border. In contrast, the whole surface of the floating trophozoite was smooth without any cell projections. The developed projections in the former type of trophozoite may contribute to their firm attachment to the epithelial cells and/or to absorption of nutrients via the epithelial cells. Against the myxosporean infection, the lamprey as the host exhibited a local immune reaction by disposition of numerous lymphocytes and macrophages into the epithelium of urinary tubules.