
题名: 指环虫的生态学及我国内陆水体单殖吸虫的分布特征
作者: 夏晓勤
答辩日期: 1997
导师: 沈韫芬 ; 王伟俊
专业: 水生生物学
学位: 博士
关键词: 单殖吸虫 ; 指环虫 ; 生态虫 ; 季节动态 ; 空间分布 ; 频率分布 ; 地理分布 ; 数学模型 ; 孵化
摘要: 本文报道了作者在1992-1997年期间对我国淡水鱼类寄生指环虫的生态学和内陆水体单殖吸虫分布特征的研究。研究包括环境因子对指环虫繁殖与存活时间的影响、指环虫的季节动态、种群的频率分布与空间分布特点、指环虫的种内种问关系及单殖吸虫与鳋类的关系、我国内陆水体单殖吸虫种类组成特点、单殖吸虫的宿主分布与宿主特异性、内陆水体单殖吸虫的分布区划等方面的内容。在实验室里研究了离体小鞘指环虫的产卵特点。运用方差与均数之和聚集度两个指标，并结合Lorenz曲线分析了产卵量的个体差异，发现成熟个体产卵数量的离散程度并不高。温度于产卵量有重要的影响，小鞘指环虫在14 ℃产卵最多，估计该虫在寄生状态下平均每虫每小时可产0.3卵。在孵化实验中，研究了温度、光照、宿主粘液等因子对几种单殖吸虫孵化析影响。其中温度对于孵化率与孵化速率的影响是普遍的；光照能刺激小鞘指环虫和鲢指环虫虫卵的孵化，但对河鲈锚首虫虫的孵化没有影响；宿主的粘液也能刺激纤毛幼虫的孵出。虫卵对于干燥的耐受力很弱。纤毛幼虫的寿命呈现明显的偏态分布特征，大多数纤毛幼虫在孵出后不太长的时间内死亡，而少数个体则可存活较长的时间，甚至可达13天以上。温度下降可延长小鞘指环虫纤毛幼虫的寿命，但在12-28 ℃的温度范同内鲢指环虫纤毛幼虫的寿命没有显著的差异。然而光线的刺激可大大缩短鲢指环虫纤毛幼虫的寿命。小鞘指环虫成虫的离体死亡情况（死亡的时间分布)在4 ℃和12 ℃时很相似，为同一种型式，在20 ℃和28 ℃和则又是另外一种类型。该虫在以上四种温度条件下的离体存活时间平均为157.65小时、 176.53小时、45.50小时和37.43小时有的个体在4 ℃时可在曝气自来水中存活12天以上。在15 ℃-24 ℃的水温条件下，该虫感染宿主后大约可存活1月。鲢指环虫在12 ℃、20 ℃和28 ℃时的平均离体存活时问为136.83小时、102..15小时和8.33小时。经多种概率分布拟合的对比，证明负二项分布是指环虫在宿主种群中的频率分布型式的上佳模型。建立了一种聚集度指标—聚集度。运用该指标对指环虫种群频率数据进行分析，结果表明指环虫种群聚集分布的程度随丰度的上升而下降。聚集度与感染率之问呈线性负相关关系。各种指环虫种群的季节变动情况很明显。小鞘指环虫从每年的冬季开始出现，到次年春末(四月)，感染率与丰度均发展到高峰，以后而随着水温的上升而迅速消失，到六月上旬，感染率与丰度降至零。鲢指环虫周年存在，在晚春和早夏，其种群量最大，在晚秋也有一小高峰。弯茎指环虫、葱状指环虫和托盘指环虫的丰度高峰依次出现在4月、6月和8月。在各指环虫发生的高峰，其种群聚集分布的程度最低，而平均拥挤度为最高。通过数学模型的建立与分析，可以预测指环虫在生态条件甲一的情况下很可能造成疾病的流行。指环虫的空问分布呈现了复杂的情况。小鞘指环虫在宿主最外侧的鳃片上寄生数量最多；在感染度很小时，小鞘指环虫多寄牛在鳃片的背区(最弯处)；小鞘指环虫大多寄生于鳃丝的远段(尖端)。鲢指环虫在各片鳃上的分布数量没有显著差异，它们在每片鳃上的位置主是中区与腹区，并且大多位于鳃丝的远段和中段。小鞘指环虫与鲢指环虫在各位点的寄生数量呈负相关关系。葱状指环虫在第一、二片鳃上的寄生数量差别不大，但在第三片鳃上的寄生量较少，第四片鳃上的寄生量更少。而弯茎指环虫和托盘指环虫没有表现出明显的鳃片选择性。指环虫的空间分布是微生境中理因子、个体活动能力、寄生密度、生殖策略、种间关系等诸多冈素共同作用的结果。各虫的生态位宽度均随感染度上升而扩展。根据对已有资料的整理和统计，截至1997年7月止，我国内陆水体中已发现的单殖吸虫达575种，分属9科46属，种类最多的是指环虫科、锚首虫科、双身虫科和三代虫科，而其中又以指环虫利的种类最多，占单殖吸虫总数的的62.61%。被寄生的宿主达3纲6科253种。绝大部分单殖吸虫奇生于鱼纲，寄生于两栖纲和爬行纲的单殖吸虫总共才发现9种。指环虫科和锚首虫科单殖吸虫的宿主特异性比较接近，三代虫科次之．双身虫科又次之。根据对单殖吸虫地区分布数据进行聚类分析的结果，并参照淡水鱼类的地理区划，可将我国内陆水体的单殖吸虫划分为五区：华东区、华西区、宁蒙区、怒澜区和东洋区。
英文摘要: Ecological studies on monogeneans on freshwater fishes during the period from 1992 to 1997 and the distribution feature of Monogenea in inland water of China were reported. Several aspects were covered including the effects of environmental factors on the fecundity and survival of Dactylogyrus spp., the season 1 dynamics of Dactylogyrus spp., the frequency and spatial distribution of Dactylogyrus spp. populations; the intraspecific and interspecific relationship of Dactylogyrus spp. and the relationship between monogeneans and copepods, the composition of Monogenea in inland water of China, the distribution of monogenenas on hosts and host-specificity, the distribution of monogeneans in different districts of China, and so on. The characteristics of oviposition of D. vaginulatus Zhang et Niu, 1966 was studied in laboratory. The difference of numbers of laid eggs among individuals was measured by variance to mean ratio, degree of aggregation, and Lorenz curves. It was found that the degree of dispersion among all adult individuals is not too high. Temperature may act as a key factor to the counts of eggs laid by every individual. Individuals laid more eggs at 14 ℃ than at other temperature conditions. It was assumed a single adult individual of D. vaginulatus could lay 0.3 egg in 1 hour when parasite on the host. The effects of temperature, light and host mucus on egg hatching of several species of monogeneans were investigated. Temperature showed an extensive influence on the duration of time for hatching and the hatching rate. Light was a stimulus to the egg hatching of D. vaginulatus and D. hypophthalmichthys on Hypophthalmichthys molitrix, but had no effect on the eggs of Ancyrocephlus mogurndae on Siniperca chuatsi. Mucus from hosts activated the hatching of D. vaginulatus and A. mogurndae. Eggs were vulnerable to drought. The free-swimming ciliated oncomiracidia showed a wide spectrum of life-span. In case of failing to infect host, some larvae might die within 1 hour, while a few did not lose their reaction on provoking until 13 days after hatching. Slanting distributions were observed in life-span of the larvae, and most larvae can not survive a longer period of time. The decline of temperature is helpful for elongating the life-span of D. vaginulatus larvae. However, There is no obvious variation of the life-span of D. hypophthalmichthys larvae while the water temperature variates from 12 ℃ to 28 ℃. The presence of light can shorten greatly the life-span of D. hypophthalmichthys larvae. The mortality distribution of D. vaginulatus adult on time at 4 ℃ is quite similar to that at 12 ℃, while the mortalitys at 4 ℃ and at 12 ℃ are almost the same. It seperated from host, adult worms survived about 157.65 hours, 176.53 hours, 45.50 hours and 37.43 hours at 4 ℃, 12 ℃, 20 ℃ and 28 ℃ respectively. This parasite species has a life-span about 1 month on the host at temperature ranging from 15 ℃ to 24 ℃. The adult of D. hypophthalmichthys survived about 136.83 hours, 102.15 hours and 8.33 hours in aerated tap water at 12 ℃, 20 ℃ and 28 ℃ respectively. The negative binomial distribution was proved to be an excellent model to the frequency distribution of Dactylogyrus spp. by comparing to other nine kinds of probability distributions. An index named as degree of aggregating was established to measure the level of aggregation in a population. This index indicates the level of aggregation decreases as the abundance increases. Negative linear correlation between degree of aggregation and prevalence was found in populations of D. vaginulatus and D. hypophthalmichthys. The population of Dactylogyrus spp. shows obvious seasonal dynamics. After appearing in winter; the population of D. vaginulatus increased sharply. The peak of the prevalence used to be observed in April of the following year. The populations size then decreased quickly as the temperature rose up. The prevalence fell to zero in eartly June. D. hypophthalmichthys can be found throughout the year. The prevalence and abundance reached maximum in late spring or early summer, and abundance was high also in late autumn. The abundances of D. curvicirrus, D. chenminjungae and D. montschadskyi on Culterichthys erythropterus appeared successively in April, June and August. The degree of aggregation decreased to the lowest and mean crowding increased to the highest when the abundance of Dactylogyrus spp. population reached their peaks. The mathmatical model for the development of Dactylogyrus spp. population suggests the infection of Dactylogyrus spp. might cause diseases under certain ecological conditions. The spatial distributions are quite complex. The number of D. vaginulatus on the outest gill arches was greater than other gill arches. When intensity is low, most of D. vaginulatus were located at the dorsal part of gill arches and prefered to the distal end of gill filaments. There was no significant difference of the numers of D. hypophthalmichthys located at 4 gill arches. This parasite species shows preference to the median part and the ventral part of gill arches, and the distal end and the median segment of gill filaments. too. Significant negative correlation exists between D. vaginulatus and D. hypophthalmichthys at each site. It seems that the number of D. chenminjungae decreases successively from outer gill arches to inner gill arches, except that there is no significant difference of the intensity between on the first gill arch and the second gill arch. D. curvicirrus and D. montschadskyi show no preference to gill arches. Spatial distribution patterns of parasites indicates the effects of physical and chemical factors in microhabitat, the motility of individuals, intensity, reproductive strategy, intenspecific relationship, Niche breadth extends as intensity increases. By July of 1997, 575 species of monogeneans, belonging to 9 families and 46 genera, have been discovered in inland water of China, mainly composed of Dactylogyridae (62.61%), Ancyrocephalidae (19.30%), Diplozoidae (6.26%) and Gyrodactylidae (6.78%). 253 species of hosts cover 3 classes, 6 families. Most of monogeneans parasitize on fish and the total is only 9 species on Amphibia and Reptilia. The host specificity of Dactylogyridae is similar to that of Ancyrocephalidae. Gyrodactylidae is less specific to host than Dactylogyridae and Ancyrocephalidae, but more than Diplozoidae. According to the result of cluster analyses to distribution of monogeneans and to the region division of freshwater fish, Monogenea in inland water of China can be divided into into geographical groups, they are East China Region, West China Region, Ning-Meng Region, the Lu-Lan Region and Oriental Region.
语种: 中文
内容类型: 学位论文

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