【作者】 罗祖奎；

【导师】 王天厚；

【作者基本信息】 华东师范大学 ， 生态学， 2010， 博士

【摘要】 为满足不断增长的人口需求养殖业在世界范围内迅速发展,大量的养殖鱼塘被构建,与此同时,鱼塘抛荒事件也高频率发生。鱼塘抛荒的原因主要有致病微生物感染鱼而被迫停止养殖、水质化学污染、管理不当导致经济收入低下、鱼塘土地所有权与使用权纠缠不清等。对抛荒湿地研究一种比较普遍的观点认为：抛荒引起湿地物种多样性下降,或者湿地被低保护价值的物种入侵,总体而言,抛荒对物种生存环境功能的整体性不利。多种农事活动,比如：砍割、放牧、烧荒、养殖等在抛荒后的湿地中停止,而这些传统的或者低强度的农事活动相当于中度干扰,有利于湿地物种多样性,湿地物种对这些农事活动具有一定程度的依赖性。崇明东滩(N 31°25’-31°38’,E 121°50’-122°05’)位于崇明岛的东端,崇明东滩98大堤内侧的人工鱼塘从2008年5月开始被抛荒。农事活动,比如：鱼塘饲料投放、水位管理等在人工鱼塘停止养殖业后也停止,这意味着渔农对人工鱼塘的管理调节活动也停止,这可能引起这些人工鱼塘的水鸟多样性下降。而崇明岛位于“东亚-澳大利西亚”候鸟飞行路线上,是亚太地区迁徙水鸟的重要中转驿站和越冬地,被世界自然基金会(WWF)列为具有国际重要意义的生态敏感区。而且,崇明东滩自然保护区是国家级自然保护区,自2002年1月列入“拉姆萨尔国际湿地保护公约”国际重要湿地名录,由湿地公约正式指定为“国际重要湿地”。而98大堤内侧的人工鱼塘是崇明东滩自然保护区功能上的缓冲区,对该区域人工鱼塘的水鸟及其生境保护无疑具有重要的意义。食物是影响水鸟多样性和分布的重要生态因子之一,而崇明岛位于候鸟迁徙路线的中段,是途中候鸟能量补充的重要场所,对该区域水鸟食物的研究显得尤为重要。我们试图搞清楚崇明东滩98大堤内侧人工鱼塘水鸟对鱼塘抛荒的反应,以及食物(以大型底栖动物作为代表)的变化情况,我们进行了以下实验：在2007年5月-2009年5月,每间隔10-18天对人工鱼塘以及邻近的公园(作为对照区)进行一次水鸟调查,即：在人工鱼塘和公园两个样方每年的夏季分别进行了5次、其它三个季节6次的水鸟调查。同时,对鱼塘和公园两个样方两年内每个季节各进行一次大型底栖动物采集,获得大型底栖动物的数量并处理得到干重和去灰分干重。鱼塘从2008年5月开始被抛荒,为了便于描述,我们将2007年5月-2008年5月和2008年5月-2009年5月在鱼塘分别称为抛荒前和抛荒后,在公园分别称为第一时间段和第二时间段。主要的研究结果和结论如下：1).鱼塘抛荒后水鸟和大型底栖动物的多样性均显著低于抛荒前的多样性。鱼塘抛荒前和抛荒后两年内共记录到水鸟14057只,其中,12154只,即86.5%的水鸟在抛荒前被记录；1903只,即13.5%的水鸟在抛荒后被记录。以每条样线上记录到的水鸟数量为一个计数进行线性回归分析,结果显示：抛荒前水鸟数量显著高于抛荒后的数量(R=0.598,P=0.003)。鱼塘抛荒前和抛荒后共统计到60种水鸟,其中,抛荒前统计到54种,抛荒后统计到38种。以每条样线上记录到的水鸟种类数为一个计数进行线性回归分析,结果显示：抛荒前水鸟种类数显著高于抛荒后水鸟种类数(R=0.661,P=0.001)。COMDYN模型分析表明：鱼塘抛荒前水鸟种类各季节的观测数和估计值均高于抛荒后水鸟种类对应季节的观察数和估计值,水鸟种类相对丰富度为抛荒前高于抛荒后,抛荒前与抛荒后物种种类相对丰富度差异夏季最大,冬季最小。对鱼塘水鸟的调查中,有6种水鸟是仅在鱼塘抛荒后记录到的,相比而言,有22种水鸟是仅在抛荒前记录到的。抛荒前的夏、秋、冬、春季分别有4、3、6、2种鸟类在数量上显著高于抛荒后的对应季节(P<0.05)。相对比而言,抛荒后的夏、秋、冬、春季分别有0、1、3、1种鸟类在数量上显著高于抛荒前的对应季节。鱼塘抛荒前与抛荒后数量差值和种类差值最大的都是雁形目的水鸟,雁形目的水鸟数量抛荒前是抛荒后的19倍,种类抛荒前比抛荒后多10种。鱼塘食物丰富度和水位下降等可能是抛荒后水鸟多样性下降的主要原因。实际上,抛荒前比抛荒后存在一些不利于水鸟生存的人为因素。比如：抛荒前投喂饲料等人为干扰可能惊飞水鸟,投喂有机饲料造成有机质腐烂和鱼塘消毒的化学药品引起水质下降,这些都对水鸟的生存不利。但是,抛荒前水鸟多样性反而高于抛荒后水鸟多样性,这说明：水鸟已经适应了崇明东滩鱼塘的渔农养殖活动带来的干扰,甚至对规律性的人为活动具有一定的依赖性,鱼塘抛荒对水鸟多样性有明显的负面影响,对水鸟生存的环境功能整体性不利。大型底栖动物共分软体动物、甲壳动物、环节动物、昆虫幼虫和其它五个大类。将鱼塘抛荒前和抛荒后的这五个大类的大型底栖动物对应季节的密度、干重和去灰分干重三个指标分别进行对比,结果表明：软体动物、甲壳动物、环节动物、昆虫幼虫四大类的三个指标在对应季节基本上都是鱼塘抛荒前高于抛荒后,但其它大类在多个季节无显著差异。抛荒前渔农向鱼塘内不定期的抛撒大量活的螺和摇蚊幼虫等作为饲料,这些大型底栖动物在鱼塘抛荒前形成一个临时的高密度,是导致鱼塘抛荒前大型底栖动物密度显著高于抛荒后大型底栖动物密度的原因之一。另外,抛荒后的干旱,也是导致鱼塘抛荒前大型底栖动物密度显著高于抛荒后大型底栖动物密度的原因之一。2).鱼塘抛荒事件引起鱼塘和公园(对照区)水鸟重新分布鱼塘样方中,抛荒前和抛荒后水鸟多样性变化较大的是雁形目、鸻形目和鸥形目的水鸟。抛荒后雁形目和鸥形目的水鸟种类和数量呈现下降趋势,而鸻形目水鸟种类和数量有上升趋势,这与鱼塘样方的水位和食物的可获得性是相关的。在鱼塘抛荒前,高水位有利于雁形目的水鸟(主要是鸭),冬季鱼塘捕捞活动引起鸥形目水鸟临时性的聚集,但是,高水位不利于鸻鹬类的捕食。所以,即使在鱼塘抛荒后比抛荒前大型底栖动物的密度低,但抛荒后的低水位使鸻鹬类食物可获得性反而增加,导致抛荒后鸻鹬类的数量上升。公园内第一时间段和第二时间段对应季节水鸟种类相对丰富度都接近1：1。但是公园第二时间段比第一时间段冬季的水鸟数量显著增加,增加的水鸟基本是雁形目的鸟类(主要是鸭),而其它三个季节两个时间段水鸟数量差异均不显著。冬季雁形目水鸟在公园两个时间段数量都很丰富与公园一直保持高水位有关。从鱼塘和公园两个样方对比来看,不同类别的水鸟对鱼塘抛荒事件反应有很大的差别,比如：雁形目的水鸟在鱼塘表现出抛荒后种类和数量下降,而在公园第二时间段种类和数量上升；鸻形目的水鸟在鱼塘表现出抛荒后种类和数量上升,而在公园两个时间段的调查中种类和数量没有明显变化；鹈形目的水鸟仅在抛荒前的鱼塘记录到,在抛荒后的鱼塘和公园的两个时间段均未记录到。水鸟的这些反应上的差别说明：鱼塘抛荒对适应不同栖息生境的水鸟影响不同,导致不同生态习性的水鸟对鱼塘抛荒事件在生态位重新选择上有很大的差异。3).整个实验阶段,大型底栖动物的密度均是鱼塘显著高于公园抛荒前渔农向鱼塘内不定期的投喂大量活的螺和摇蚊幼虫等作为饲料,这些大型底栖动物在鱼塘抛荒前形成一个临时的高密度,是导致鱼塘抛荒前大型底栖动物的密度显著高于抛荒后的原因之一。抛荒后的干旱导致了鱼塘大型底栖动物密度显著性下降,但是,大型底栖动物的密度在鱼塘抛荒后还是显著高于公园内大型底栖动物的密度。公园大型底栖动物密度较低可能有以下原因：公园在构建时,多底栖动物和富营养的表层土被运走,深的底泥构成了河床,而且公园历史不长,导致底栖动物不丰富；另外,公园河床的沙质土也可能不利于底栖动物的繁衍。4).食物因素不是引起鱼塘抛荒早期阶段水鸟多样性下降的关键因子把鱼塘和公园的水鸟数量对比,鱼塘抛荒前、公园第一时间段、公园第二时间段三者之间水鸟数量差异不显著,但这三者的水鸟数量都显著高于鱼塘抛荒后水鸟的数量。而整个实验阶段,大型底栖动物的密度均是鱼塘显著高于公园。这说明水鸟多样性的变化与大型底栖动物分布不一致,表明食物因素不是引起鱼塘抛荒早期阶段水鸟多样性下降的关键因子,很多水鸟偏爱某一区域可能受到多种生境特点联合体的影响,单个因子很难解释湿地水鸟多样性变化的原因。水鸟对鱼塘抛荒的反应以及食物因子分析可能需要一个更长时间的研究,我们的研究是整个研究工作的一个阶段性工作,能为整个研究工作提供前期的基础数据和研究思路。更多还原

【Abstract】 Aquatic farming is developing rapidly in the world for the increasing population. A large number of aquaculture ponds are being constructed, and ponds are being frequently abandoned at the same time. The main reasons for pond abandonment include the occurrence of disease-causing microorganisms that force aquatic farming to stop, water contaminated by chemical toxic substances, bad management that leads to a low income, and the tangle of ownership and usufruct of ponds.A prevalent view to wetland abandonment is that it begets the decline of species, or abandoned sites are invaded by low value species. Generally speaking, wetland abandonment is disadvantage with the holistic function of species habitats. Various farming activities, such as cutting, grazing, firing, and aquatic farming, terminate in the abandoned sites. These farming activities are beneficial to the maintenance of species diversity in the wetland, because these traditional or low intensity farming activities play the role of intermediate disturbance. Species in the wetland are dependent of the farming activities to some extent.Chongming Dongtan (N 31°25’-31°38’,E 121°50’-122°05’) is located on the east end of Chongming Island, and the aquaculture ponds inside 98 levee of Chongming Dongtan has been abandoned since May 2008. Farming activities, such as forage casting and water management terminated with the stop of aquatic farming in the ponds, which simultaneously implies the stop of the managements and regulations to these ponds from fishing farmers. This pond abandonment event may beget the decline of waterbird diversity. Chongming Island is located in the migrant bird flyway of "East Asia-Australia", and it is the important stopover and overwintering site for migrant birds of Asia Pacific zone, and it is listed as one of the most sensitive ecological zone internationally by WWF. Furthermore, Chongming Dongtan Nature Reserve is national class nature reserve, and it was listed in the international important wetland of "Ramsar Convention" and was designated as "international important wetland". The aquaculture ponds inside 98 levee of Chongming Dongtan are the buffer area for the nature reserve. Therefore, it is undoubted that the protection to the waterbirds and their habitats of Chongming Island is of most importance.Diet is one of the most important ecological factors that affect waterbird diversity and distribution. It is of especially importance to study waterbird diet at Chongming Island, because Chongming Island is located in the middle of migrant bird flyway, and Chongming Island is the important food compensatory site for migrant bird. We tried to probe into the response of waterbird to pond abandonment in the aquaculture ponds inside 98 levees of Chongming Dongtan, and we tried to know the status of waterbird diet (macrobenthos as delegate). We conducted bird survey at 10-18 day intervals in the aquaculture ponds and adjacent park (as controlled zone) between May 2007 and May 2009, i.e. we conducted 5 surveys in summer and 6 surveys in other three seasons in the aquaculture ponds and in the park each year. At the same time, we sampled macrobenthos once each season in the aquaculture ponds and in the park in the two years, and we got the dry weight and ash free dry weight of macrobenthos. The aquaculture ponds have been abandoned since May 2008. In order to describe clearly, May 2007-May 2008 and May 2008-May 2009 were demarcated as pre-abandonment and post-abandonment in the ponds, respectively; and were demarcated as 1st time-period and 2nd time-period in the park, respectively.The results and conclusions are as follows:1). The diversities of both waterbird and macrobenthos in the ponds pre-abandonment are significantly higher than those in the ponds post-abandonment.We recorded a total of 14057 waterbird observations in the pre-and post-abandonment ponds. Of these,12154 (86.5%) waterbirds were recorded pre-abandonment and 1903 (13.5%) post-abandonment. A linear regression model showed a significant higher waterbird abundance pre-than post-abandonment in the ponds, based on the waterbird number recorded in each sample line as a count (R= 0.598, P= 0.003). We recorded a total of 60 waterbird species in the pre-and post-abandonment ponds. Of these,54 species were recorded pre-abandonment and 38 post-abandonment. A linear regression model showed a significant higher waterbird richness pre-than post-abandonment in the ponds, based on the waterbird species recorded in each sample line as a count (R= 0.661, P= 0.001). An analysis of COMDYN model showed that both the observed number of species and the estimated number of species were substantially higher pre-than post-abandonment for all seasons, and the relative species richness was obviously higher pre-than post-abandonment. The disparity in relative species richness between pre-and post-abandonment was greatest in summer and lowest in winter. Only 6 species were observed exclusively post-abandonment during our surveys. In contrast,22 species were recorded exclusively pre-abandonment. There were 4,3,6, and 2 species for summer, autumn, winter, and spring, respectively, which had significantly higher abundances pre-than post-abandonment (P< 0.05). In contrast, only 0,1,3, and 1 species had significantly higher species abundance post-than pre-abandonment. Waterbirds in taxonomic order Anseriformes varied most both in abundance and richness between pre-and post-abandonment ponds. Anseriformes was 19 times the abundance and 10 more species were found pre-vs. post-abandonment.The ecological factors, such as diet abundance and water level decline, may the main reasons that led to the reduction of waterbird diversity when the ponds were abandoned. In fact, more artificial disturbances were disadvantage with waterbird pre-than post-abandonment. These artificial disturbances, such as forage casting that may flush waterbird, and low water quality arising from rotten organic materials by casting organic forage and arising from chemical toxic substances by pond disinfection. All these activities were disadvantage with waterbird, but higher abundance and richness of waterbird were recorded pre-than post-abandonment. In brief, waterbird has adapted to the disturbance arising from aquatic farming in the ponds of Chongming Dongtan, and waterbird was even dependent of seasonal farming activities. The pond abandonment event affected negatively the waterbird diversity and was disadvantage with the holistic function of species habitats.Macrobenthos were categorized into Mollusks, Subphylurm crustaceea, Annelida, Insect larva and Others in our study. We compared density, dry weight and ash free dry weight of the forementioned five categories in corresponding seasons between pre-and post-abandonment. The results indicated that four categories, including Mollusks, Subphylurm crustaceea, Annelida and Insect larva, almost were higher pre-than post-abandonment in corresponding seasons in density, dry weight and ash free dry weight, but category Others was of no significant difference in most corresponding seasons.A large number of spiral shell and Chironomidae larva alive was casted into the aquaculture ponds aperiodically as forage by fishing farmers pre-abandonment, which formed a temporal high density of macrobenthos in the ponds pre-abandonment. This may be one of the reasons that led to density of macrobenthos significant higher pre-than post-abandonment. Furthermore, the dry period post-abandonment may also be the reason that led to density of macrobenthos significant higher pre-than post-abandonment.2). Pond abandonment event begot a new distribution of waterbird in the ponds and park (controlled zone).Variations of waterbird diversity were most obvious in taxonomic orders Anseriformes, Charadriiformes and Lariformes between pre-and post-abandonment ponds. The abundance and richness of waterbirds in Anseriformes and Lariformes declined when the ponds abandoned, but the abundance and richness of waterbirds in Charadriiformes increased. This result may correlate to water level and food available in the ponds. During pre-abandonment, the high water level were helpful to increase diversity of waterbirds in Anseriformes (mainly ducks), and fish harvesting activities begot a temporal assemblage of birds in Lariformes in winter, but high water level were disadvantage with waterbirds in Charadriiformes to prey. Therefore, there was a lower density macrobenthos post-than pre-abandonment, but there was a higher diet available in the post-abandonment ponds instead, which led to an increase of waterbirds in Charadriiformes.All the relative richness of waterbird approached to 1:1 in the corresponding seasons between 1st time-period and 2nd time-period in the park. Waterbird abundance increased significantly during 2nd time-period than during 1st time-period in the corresponding winters, but there was no significant difference in the other three seasons between the two time-periods. The increment of waterbird in the park in winter substantially consisted of waterbird in Anseriformes (mainly ducks). That waterbird in Anseriformes was abundant in the park in the two time-periods may correlate to high water level.Different waterbird responded distinctively to pond abandonment by comparing waterbirds in the ponds and waterbirds in the park. For example, abundance and richness of waterbirds in Anseriformes declined in the post-abandonment ponds, but they increased in the park during 2nd time-period. Abundance and richness of waterbirds in Charadriiformes increased in the post-abandonment ponds, but they have no obvious difference in the park between the two time-periods. Abundance and richness of waterbirds in Pelecaniformes occurred only in the pre-abandonment ponds, but they were never recorded in post-abandonment ponds and in the park during the two time-periods. The distinctive responses of waterbird indicated that pond abandonment have different impacts on waterbirds adaptive to different habitats, leading to waterbirds with ecological different habits have great disparity on pond abandonment in niche re-choice.3). Densities of macrobenthos were all higher in the ponds than in the park during the whole experimentA large number of spiral shells and chironomidae larvas alive were casted into the aquaculture ponds aperiodically as forage by fishing farmers pre-abandonment, which formed a temporal high density of macrobenthos in the ponds pre-abandonment. This may be one of the reasons that led to density of macrobenthos significant higher pre-than post-abandonment. Dry period post-abandonment led to a sharp reduction in density of macrobenthos in the ponds, but the density of macrobenthos in the post-abandonment ponds were still higher than that in the park. The reason that there was a low density of macrobenthos in the park may be as follows. Firstly, topsoil with abundant mcorbenthos and nutrition was carried away when the park was constructed in recent years, and the new riverbed was made of deep soil, which may lead to a low abundance of macrobenthos. Secondly, sandiness riverbed in the park could inhibit macrobenthos development. 4). Diet was not the key factor that begot decline of waterbird diversity in the abandoned aquaculture ponds at the early stage.There were no significant differences between the ponds pre-abandonment, the park 1st time-period and the park 2nd time-period, but they were all significantly higher than the ponds post-abandonment, when comparing waterbird abundance in the ponds and park. Variations of waterbird diversity differed completely from the distribution of macrobenthos, which indicated that diet was not the key factor that begot decline of waterbird diversity during the early stage of abandoned aquaculture pond. Habitat preference of waterbird in an area may affected by combined habitats, and such a complex variation course of waterbird diversity may be inexplicable by a single factor.Our study about waterbird responses to pond abandonment at the early stage and diet analysis may need a longer time. Our study is a phase work for the whole study about waterbird responses to pond abandonment, and we could offer the whole study with basic prophase databases and study idea.更多还原