【作者】 王银东；

【导师】 熊邦喜；

【作者基本信息】 华中农业大学 ， 水产养殖， 2005， 博士

【摘要】 长江中下游湖泊普遍存在富营养化、生物多样性下降和生态功能退化的现象,严重影响湖泊的可持续发展。大型底栖动物是湖泊生态系统中的重要组成部分,发挥着多种重要的生态功能。由于水生态系统环境的恶化,大型底栖动物的自然资源日益受到破坏,而我国在大型底栖动物生态学研究相对较少,水栖寡毛类和水生昆虫类遗传多样性方面的研究还未见报道。因此,有必要对湖泊大型底栖动物的生态学和遗传多样性进行研究,以查明在人类活动下大型底栖动物的结构特点,提供解决湖泊富营养化和湖泊渔业持续发展理论依据,并为大型底栖动物资源保护和系统发育的研究奠定基础。 为此,本研究对长江中游富营养化的浅水湖泊（南湖）环境现状进行了调查,查明了大型底栖动物的群落结构及环境变化对其影响,计算大型底栖动物群落的生产力,对水栖寡毛类颤蚓科动物和摇蚊幼虫的RAPD扩增条件进行优化,并分析了大型底栖动物优势种的遗传多样性,主要研究结果如下: 1、武汉南湖水体的理化性状分别为:采样点平均水深为2.31m,年均水温为17.97℃,年均SD为33.63cm,pH平均为8.25,DO含量平均为8.17mg/L,电导率均值为393.44μs/cm:水体中NH₄⁺-N平均浓度为3.603mg/L,NO₃^--N为2.072mg/L,NO₂^--N为0.155mg/L,TN为7.033mg/L;PO₄^3--P平均为0.184mg/L,TP为0.761mg/L;N∶P比平均为9.357。沉积物中TN为4.765‰,TP含量平均为0.528‰,沉积物中N∶P比平均为8.74。浮游植物共发现66种,密度和生物量分别为2.489×10⁶ind/L和7.94mg/L;浮游动物共发现56种,密度和生物量分别为26285 ind/L和3.46 mg/L。根据水体中的营养盐含量,南湖为重营养型湖泊,营养盐的几个指标均已超过Ⅴ级地表水质标准。 2、南湖大型底栖动物共发现30种,其中寡毛类10种,软体动物4种,水生昆虫14种,其它动物2种,定量采样中只发现寡毛类和水生昆虫。寡毛类的年平均密度为3381 ind/m²,变幅为1606-6134 ind/m²,生物量为9.70 g/m²,变幅为2.67-26.64g/m²,其密度的季节变化为春季>夏季>秋季>冬季,生物量的季节变化为春季>夏季>冬季>秋季。水生昆虫的年平均密度为1056 ind/m²,变幅为918-1178 ind/m²,生物更多还原

【Abstract】 Most of lakes, in the middle and later reachs of the Yangtze River basin, were faced the water eutrophicated, bio-diversity decreased and eco-function degenerated, which impaired the continuance development of laky economy severely. Macrozoobenthos is an important components of lake ecosystem and play multiple functions in aqutic ecosystem. However, the natural resources of macrozoobenthos decreased gradually for the destruction of aquatic ecosystem environment. The researches on macrozoobenthos ecology were rather less. No report of the genetic diversity of aquatic oligochaeta and insecta was found in China. It is necessary to study the ecology of macrozoobenthos and the genetic diversity of aquatic oligochaeta and insecta, because the result will help people find out the characters of macrozoobenthos community in the lake under of anthropogenic activity, and provide the theoretical basis for solving the problem of lake eutrophication and the continuous development of fisheries. The result will also benefit to the resource protection and the study of molecular phylogenetic relationship of macrozoobenthos.Therefore, the basic situation of eutrophicated shallow lake （Nanhu Lake）, in the middle reaches of the Yangtze River basin, had been investigated, the communities structure and the impaction of environmental deterioration of macrozoobenthos had been analyzed, and the secondary production of macrozoobenthos had been calculated. RAPD makers was used to detect genetic diversity of five dominant species. The main results are as following:1. The physical and chemical indices of the water were measured in Nanhu Lake. The results show: The annual average water depth, water temperature and Secchi Degree of ten sampling stations in the lake were 2.31 m, 17.97 ℃ and 33.6 cm, respectively. Mean value of pH was 8.25; the average content of DO was 8.17 mg/L; conductivity was 393.44μs/cm. The mean concentration of NH₄⁺-N, NO₃^--N, NO₂^--N and TN were 3.603 mg/L, 2.072 mg/L, 0.155 mg/L, and 7.033 mg/L, respectively. The content of PO₄^3--P and TP averaged 0.184 mg/L and 0.761 mg/L, respectively. The N:P ratio was 9.357. Sixty-six species of phytoplankton were found, and its density and biomass were 2.489 ×10⁶ ind/L and 7.94 mg/L, respectively. Fifty-six species of zooplankton were found, and its density and biomass were 26285 ind/L and 3.46 mg/L, respectively. The content of TN and TP in sediment were 4.765‰ and 0.528‰, respectively. Nanhu Lake was hypereutrophicaccording to the nutritional indices of the water.2. A total of 30 macrozoobenthos taxa were recorded in Nanhu Lake, including 10 species of oligochaeta. 4 species of molluscat 14 species of aquatic insecta, 1 species of hirudinea and 1 species of decapoda. There were only oligochaeta and insecta found in the quantitative investigation of macrozoobenthos. The abundance of oligochaeta was 3381 ind/m2 and ranged from 1606 ind/m2 to 6134 ind/m2, the biomass was 9.70 g/m2 and ranged from 2.67 g/m2 to 26.64 g/m2. The seasonal variation of abundance of oligochaeta was that in Spring > Summer > Autumn > Winter, and the biomass variation was in Spring > Summer > Winter> Autumn. The abundance of insecta was 1056 ind/m2 and ranged from 918 ind/m2 to 1178 ind/m2, and had no distinct difference among seasons. The biomass of insecta was 8.09 g/m2 and ranged from 4.68 g/m2 to 13.26 g/m2and the highest in spring. The deterioration of aquatic environment resulted in the great changes of macrozoobenthos communities structure. The chironomidae groups decreased from 15 species at 16 years ago to 9 species now. Oligochaeta was mainly composed of polluted species, and mollusca was scarce. The diversity of macrozoobenthos was rather low.3. The dominant species of macrozoobenthos was Limnodrilus hoffmeisteri, Branchiura sowerbyi, Tanypus punctipennis, Propsilocerus akamusi and Chironomus semireductus in Nanhu Lake. The distribution of former four species was congregated significantly. Five dominant species were fixed with different preservation solutions, the result show: L. hoffmeisteri, B. sowerbyi, T. punctipennis and C. semireductus were suitable fixed in 8% formaldehyde solution. P. akamusi could be preservated in 8% formaldehyde solution, or in 75% ethanol, or in 75% ethanol after fixed 24 hours in 8% formaldehyde solution, but the effect was the best in 8% formaldehyde solution.4. Annual secondary production of dominant groups of macrozoobenthos in Nanhu Lake were estimated from field data. The annual P/B coefficient and production （wet weight） of five dominant species were as follow: L hoffmeisteri, 72.691 gm^yr*1, 8.74; B. sowerbyi, 5.191 gm"2yr’\ 4.82; T. punctipennis, 6.184 gm"2yr’\ 3.77; P. akamusi, 6.184 gm^yr’1, 2.70; C. semireductus, 2.625 gm’^yr’1. The production of total macrozoobenthos was 109.718 gm^yr’^wet weight), or 20.784 gm"2yr"x （dry weight）, and the energy reserves was 110.6 Kcal m^-yr’1. The fishery production of macrozoobenthos was 6.588 g-m’^yr’1 in Nanhu Lake.5. The genomic DNA of C. semireductus and B. sowerbyi were used as template DNA to optimize the RAPD-PCR reaction conditions for chironomidae and tubificidae groups, respectively. For a 25 ^L reaction system, the optimized reaction systems ofRAPD amplification for chironomidae group were as follow: the optimal condition included 10 X Reaction Buffer 2.5 juh, 2.0 mmol/L MgCl2,0.2 mmol/L dNTPs, 1.5U Taq DNA polymerase, 30 ng template DNA, 0.2 pimolfL random primer. The optimized reaction systems of RAPD amplification for tubificidae group were: the optimal condition included 10 X Reaction Buffer 2.5 fiL, 2.5 mmol/L MgCl2,0.2 mmol/L dNTPs, 1.0U Taq DNA polymerase, 30 ng template DNA, 0.3 (xmoVh random primer. The optimal program for efficient amplification included 45 cycles of denaturation at 94 °C for 1 min （94 °C for 5 min for the first cycle）, annealing at 37 ^C for 1 minute, and extension at 72 °C for 2 minutes （10 minutes for the final cycle）, then the last products were stored at 4"C.6. Random amplified polymorphic DNA （RAPD） markers was used to detect genetic diversity of five dominant populations of macrozoobenthos. Sixteen random primers were used for the RAPD of chironomidae groups, and eighteen for tubificidae groups. The results were: the percent of amplified polymorphic bands of T. punctipennis, P. akamusi, C. semireductus, L koffmeisteri and B. sowerbyi were 41.03%, 44.0%, 41.79%, 46.01%, and 51.20%, respectively. Shannon genetic diversity of their intra-populations were 0.2570, 0.2472, 0.1943, 0.3153, and 0.3355, respectively. The intra-populations genetic similarity of them were 0.8730,0.8731,0.9066,0.8285, and 0.8310.更多还原