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1.
Macrophyte community diversity and composition respond to ecosystem conservation and local environmental factors. In this study, we developed a multidimensional diversity framework for macrophyte communities, including the taxonomic and functional alpha and beta diversity. We used the framework to explore the relationships among water level regimes and these diversity parameters in a case study of China's Baiyangdian Lake. Analysis of indicators of hydrologic alteration divided the water level from 1959 to 2019 into four regimes (dry, <6.42 m; low, 6.42–7.23 m; medium, 7.23–8.19 m; high, >8.19 m). Alpha and beta diversity were significantly higher in the medium regime than in the low and high regimes. Redundancy analysis indicated that the maximum water depth significantly affected taxonomic alpha diversity, and total nitrogen (TN) and chemical oxygen demand (COD) concentration significantly affected functional alpha diversity, respectively. Mantel tests showed that TN, Secchi depth (SD), and water depth in the high water level regime significantly increased the total beta diversity and turnover components. TN was the main factor that increased total taxonomic beta diversity. Water level regime mainly influenced interspecific relationships by changing the TN and COD concentration. The water level should be maintained between the medium and high water level regimes to promote restoration of the macrophyte community and improve ecosystem stability. The biodiversity evaluation framework would provide a deeper insight into the hydrological process management for restoration of aquatic macrophyte communities in shallow lakes. 相似文献
2.
过去40年,全球气候变暖、辐射变暗和变亮、风速减弱、气候异常波动等自然环境变化以及筑坝建闸、岸堤硬质化和调水引流等强烈人类活动势必会深刻改变太湖湖泊物理环境和过程,驱动湖泊生态系统演化.基于历史文献、档案数据以及气象水文和透明度等长期观测数据,本文系统梳理了太湖气温、水温、风速、水位和透明度等物理环境空间分布和长期变化特征,探讨了气温和风速、水位和透明度相互协同作用机制及其潜在生态环境意义.受全球变化和城市化等影响,过去40年太湖气温和水温呈现显著升高趋势,而近地面风速则表现为持续下降,湖泊增温和风速下降有利于藻类生长和蓝藻水华漂浮聚集,某种程度上增加了蓝藻水华出现频次和集聚的面积.为防洪和满足流域日益增长的水资源需求,闸坝管控和调水引流使太湖水位呈现缓慢增加趋势,而入湖污染物增加和富营养化则造成水体透明度逐渐下降,致使透明度与水位(水深)的比值明显降低,减少了湖底可利用光强,恶化水下光环境,在一定程度上驱动了太湖水生植被和草型生态系统退化.湖泊物理环境长期变化逐渐拓展了太湖藻型生境空间而压缩了草型生境空间,加剧了草型生态系统向藻型生态系统转化和增强了藻型生态系统的自我长期维持.太湖湖泊物理环境的显著变化也会部分抵消流域营养盐削减和湖体营养盐下降对藻类生物量和蓝藻水华的控制,增加了太湖蓝藻水华防控和湖泊富营养化治理的难度.这意味着未来流域控源截污需要更加严格的标准,而湖泊水位等物理环境的有效管控是应对藻华加剧和恢复草型生态系统的适应性管理策略. 相似文献
3.
Javier Cotin Manuel García-Tarrasón Carolina Sanpera Lluis Jover Xavier Ruiz 《Estuarine, Coastal and Shelf Science》2011
The Ebro catchment, the largest river basin in Spain, includes various heavily industrialized areas. Among these is the Flix site, where a chemical plant has been operating since the beginning of the 20th century. This extended operational period, together with the construction of a dam next to the factory around 1960, resulted in the accumulation of large amounts of heavily polluted sediments in the adjacent riverbed, many of which are contaminated by mercury. Pollutants from Flix are carried downstream by the Ebro River to its delta. In order to assess the transfer of mercury to the complex river estuary ecosystem, we studied the ecology of the tern community living there as these birds segregate into a range of habitats. For this purpose, first we used stable isotope analysis (SIA) (δ34S, δ13C, δ15N) of eggs to determine the trophic ecology and habitat partitioning of several tern species (Common, Sandwich, Little, Gull-Billed and Whiskered Tern) breeding sympatrically, in order to link their foraging ecology with habitat types. Next we measured mercury concentrations in eggs to monitor the input of this metal into the diverse habitats. With the exception of the Little Tern, the other terns used a restricted habitat range in the Ebro Delta, as shown by C and S isotopes; the Gull-Billed and Whiskered Tern foraged in freshwater habitats, while the Common and Sandwich Tern used marine habitats. This restricted feeding behavior of the Gull-Billed and Common Tern contrasts with previous reports in other breeding sites. The Little Tern, which showed a wide range of isotopic values, was found to be an opportunistic forager but fed mainly in saltpans, a feeding habitat not reported previously for this species in this area. We found that mercury concentrations are related to foraging habitat and diet, and are unexpectedly higher in species feeding on demersal prey in marine habitats and also higher in birds feeding in saltpans than in those feeding in freshwater habitats. The mercury concentrations found in the Little and Common Tern eggs sampled in “Punta de la Banya” may be sufficiently high to endanger breeding success. 相似文献
4.
5.
徐小怡 《广东海洋大学学报》2011,31(2)
运用钻石模型分析广东省水产品加工产业的竞争力,在此基础上结合因子分析法对广东省和其他沿海地区水产品加工产业的竞争力进行比较,研究结果显示:相对而言,广东省水产品加工产业综合竞争力水平较高,但在资源利用率、加工企业规模化发展方面处于劣势,所以要从加大财政投入、推进科技创新、实现企业规模经济以及提升产品附加值和品质等方面提升广东省水产品加工产业的竞争力。 相似文献
6.
7.
为从一种组成未知的商用复合菌中分离并筛选出优势发酵菌株,本实验采用稀释平板培养法,对菌种进行分离纯化,同时参照《真菌鉴定手册》和《常见细菌鉴定手册》,根据其形态学特征、生理生化特性,并分别结合16S r DNA和18S r DNA序列的比对分析对菌种进行鉴定。另外,本研究通过生长曲线测定,单菌种发酵试验以及多菌种混合发酵发酵试验,以游离氨基酸态氮为指标,以期筛选出发酵低值水产品制备菌肥的最佳菌株组合。结果显示,共分离得到4株菌,分别为a热带假丝酵母、b罗伦隐球菌、c枯草芽孢杆菌、d蜡样芽胞杆菌。且菌种组合acd发酵后游离氨基酸态氮的含量较对照组上升最显著,为8.276g/L。故可确定最佳发酵菌株配方为acd(热带假丝酵母+枯草芽孢杆菌+蜡样芽胞杆菌)。 相似文献
8.
Factors influencing the distribution of coastal lichens Hydropunctaria maura and Wahlenbergiella mucosa 下载免费PDF全文
Responses to abiotic and biotic stresses that potentially drive the vertical zonation of the intertidal lichens Hydropunctaria maura, an upper littoral lichen, and Wahlenbergiella mucosa, a lower littoral lichen, were investigated in field and laboratory experiments. When transplanted, both lichens exhibited an inability to survive outside their normal vertical distribution range. W. mucosa appeared to be unable to tolerate prolonged periods of desiccation following translocation from lower to upper littoral regions, whereas H. maura was unable to survive in lower littoral zones possibly owing to increased grazing pressure. The effect of desiccation in both lichens was compared using pulse amplitude modulated chlorophyll fluorescence and infra‐red gas analysis; results indicated a more hydration‐dependent nature of W. mucosa. Photosynthetic (algal) pigments and phenolic compounds were determined in both lichen thalli, and a range of additional coastal lichens occupying a natural gradient from upper to lower shore levels. Pigment composition and concentration in both lichen thalli were similar whereas levels of phenolic compounds were up to three times higher in W. mucosa than H. maura. Pigment and phenolic concentration and composition exhibited some seasonality across 13 different lichens originating from different shore levels. Phenolic concentration increased towards the lower shore, suggesting a potential anti‐herbivory function. This marks the first study of pigments and phenolics in coastal lichen communities, and prompts further investigations on the particular physiological features of marine and maritime lichens that enable them to thrive in this extreme environment. 相似文献
9.
Salinity is a vital factor that regulates leaf photosynthesis and growth of mangroves, and it frequently undergoes large seasonal and daily fluctuations creating a range of environments – oligohaline to hyperhaline. Here, we examined the hypotheses that mangroves benefit opportunistically from low salinity resulting from daily fluctuations and as such, mangroves under daily fluctuating salinity (FS) grow better than those under constant salinity (CS) conditions. We compared growth, salt accumulation, gas exchange, and chlorophyll fluorescence of leaves of mangrove Bruguiera gymnorhiza seedlings growing in freshwater (FW), CS (15 practical salinity units, PSU), and daily FS (0–30 PSU, average of 4.8 PSU) conditions. The traits of FS-treated leaves were measured in seedlings under 15 PSU. FS-treated seedlings had greater leaf biomass than those in other treatment groups. Moreover, leaf photosynthetic rate, capacity to regulate photoelectron uptake/transfer, and leaf succulence were significantly higher in FS than in CS treatment. However, leaf water-use efficiency showed the opposite trend. In addition to higher concentrations of Na+ and Cl−, FS-treated leaves accumulated more Ca2+ and K+. We concluded that daily FS can enhance water absorption, photosynthesis, and growth of leaves, as well as alter plant biomass allocation patterns, thereby positively affecting B. gymnorhiza. Mangroves that experience daily FS may increase their adaptability by reducing salt build-up and water deficits when their roots are temporally subjected to low salinity or FW and by absorbing sufficient amounts of Na+ and Cl− for osmotic adjustment when their roots are subsequently exposed to saline water. 相似文献
10.
Andrea Sanchini Sönke Szidat Wojciech Tylmann Hendrik Vogel Agnieszka Wacnik Martin Grosjean 《第四纪科学杂志》2020,35(8):1070-1080
Anthropogenic eutrophication and spreading anoxia in freshwater systems is a global concern. Little is known about anoxia in earlier historic times under weaker human impact, or under prehistoric natural conditions with different trophic, land cover and climatic regimes. We use a novel approach that combines high-resolution hyperspectral imaging with µ-XRF and HPLC-pigment data, which allows us to assess chloropigments (productivity) and bacteriopigments (anoxia) at seasonal subvarve-scale resolution. Our ~9700 cal a bp varved sediment record from NE Poland suggests that productivity increased stepwise from oligotrophic Early Holocene conditions (until ~9200 cal a bp ) to mesotrophic conditions in the Mid- and Late Holocene. Natural eutrophication was mainly a function of progressing landscape evolution with intense weathering under dense forest and warm-moist climatic conditions. Generally, anoxia increased with increasing productivity. Seasonal anoxia and some multi-decadal periods of meromixis were the common mixing patterns throughout the Holocene except for a period of persisting meromixis between ~5200 and 2000 cal a bp. Anthropogenic deforestation around 400 cal a bp resulted in substantially better lake oxygenation despite high productivity. In this small lake, aquatic productivity and lakeshore forest cover (wind shield) were more important factors controlling oxic/anoxic conditions than Holocene temperature variability. 相似文献