城市河湖生态系统健康评价——以北京市“六海”为例

健康的城市河湖才能发挥生态环境功能,体现景观和人文价值。城市河湖健康评价是城市河湖科学管理和生态恢复的前提和基础。对城市河湖生态系统健康概念和内涵进行了探讨,建立了评价指标体系和评价模型。以北京“六海”为例,对各子湖的健康状况进行比较评价。结果表明,中海和南海处于不健康向临界转化的状态,其余4个湖均处于不健康状态;水环境质量、水生态系统结构和功能以及水滨空间结构是影响“六海”健康水平的制约因素;除南海外,各湖的健康程度都处于很差的级别。中海和南海的整体生态环境好于其余4湖,对健康和临界状态的隶属度之和接近0.6,可恢复程度处于中等水平;其余4湖对健康和临界状态的隶属度之和均小于0.3,恢复困难。对“六海”的生态恢复和科学管理提出建议:①控制点源、面源污染,改善入湖和湖水水质;②改善“六海”的水文条件;③恢复水生态系统结构和水滨空间。     

Non-native freshwater fishes in Norway: history, consequences and perspectives

At present, there are 43 self-sustaining fish species in Norwegian fresh waters, 11 (26%) of which are non-native, representing four families (Salmonidae, Cyprinidae, Centrarchidae and Ictaluridae). Human-mediated fish introductions probably began in the 15th century with common carp Cyprinus carpio, but most have occurred between the late 1800s and late 1900s. The number of known established populations varies from one (goldfish Carassius auratus ) to nearly 250 (tench Tinca tinca ). Dispersal risk is also highest with tench, which is being spread by anglers for its appeal as a trophy fish. Intentional introductions to improve amenity angling have been part of fisheries management programmes ( e.g. brook trout Salvelinus fontinalis ), so this appears to be an increasingly common introduction vector despite the prohibition under legislation of introducing any species of non-native fishes. Some introduced species, such as brook trout, have declined in abundance and number of populations as the quality of acidified waters has been restored, being replaced by native brown trout Salmo trutta . Further range expansion by some species ( e.g. common carp, goldfish and pumpkinseed Lepomis gibbosus ) is probably restricted by current climatic conditions.     

Sedimentation in fluvial and lacustrine environments

Sedimentation in rivers is dominated by a complex set of physical processes, associated with the unidirectional flow of water. Variations in these processes give rise to different fluvial channel types, whose character can commonly be recognised in the ancient record. Chemical and biological processes are comparatively unimportant in fluvial sedimentation. In contrast, physical, chemical or biological processes can each dominate sedimentation in lakes. Physical (clastic) deposition dominates in high-latitude and mountain lakes (in which chemical and biological activity are low), and in lakes with high relief of the drainage basin and lake floor. Its variety reflects a range of processes influenced by river inflow, wave and current action, thermal and density effects. Economic benefits from the study of lake and river sedimentation include both resource and environmental aspects. An example is given of a mercury pollution study in a fluvial ecosystem. It shows that return to background levels can take place within a relatively short interval after cessation of pollutant input.     

Health Effects of Toxin-Producing Cyanobacteria: “The CyanoHABs”

Increasingly, harmful algal blooms (HABs) are being reported worldwide due to several factors, primarily eutrophication, climate change and more scientific monitoring. All but cyanobacteria toxin poisonings (CTPs) are mainly a marine occurrence. CTPs occur in fresh (lakes, ponds, rivers and reservoirs) and brackish (seas, estuaries, and lakes) waters throughout the world. Organisms responsible include an estimated 40 genera but the main ones are Anabaena, Aphanizomenon, Cylindrospermopsis, Lyngbya, Microcystis, Nostoc, and Oscillatoria (Planktothrix). Cyanobacteria toxins (cyanotoxins) include cytotoxins and biotoxins with biotoxins being responsible for acute lethal, acute, chronic and sub-chronic poisonings of wild/domestic animals and humans. The biotoxins include the neurotoxins; ana-toxin-a, anatoxin-a(s) and saxitoxins plus the hepatotoxins; microcystins, nodularins and cylindrospermopsins. Confirmations of human deaths from cyanotoxins are limited to exposure through renal dialysis at a haemodialysis center in Caruaru, Brazil, in 1996. A major effort to compile all available information on toxic cyanobacteria including issues of human health, safe water practices, management, prevention and remediation have been published by the World Health Organization. This paper will review our current understanding of CTP's including their risk to human health.     

Production of microcystins in calcareous Mediterranean streams: The Alharabe River,Segura River basin in south-east Spain

The development of epilithic cyanobacteria communities in a Mediterranean calcareous stream in the province of Murcia (SE Spain) was studied during the course of one year in an attempt to clarify the environmental variables that influence the production of microcystins. The predominant cyanobacteria were species of Rivularia, which formed conspicuous colonies throughout the year. Seasonally, other species were abundant: Schizothrix fasciculata, Tolypothrix distorta and Phormidium splendidum. All the species collected produced microcystins to a varying degree (up to five varieties), while the benthic community as a whole produced concentrations as high as 20.45 mg m⁻². At the same time, the presence of microcystins dissolved in water was confirmed. Among environmental variables, air temperature and silicate content were positively and strongly correlated with total microcystins, while nitrite, nitrate, orthophosphate, calcium and flow were negatively correlated with them. Dissolved microcystins were negatively correlated with microcystin LR, P.A.R. and total phosphorus and positively with rainfall. The production of microcystin YR seems to be regulated by different factors from those regulating the other main varieties (microcystin LR and microcystin RR). The data obtained indicate that all the tested benthic cyanobacteria produced microcystins in this shallow calcareous stream, which may contribute to their predominance in the prevailing conditions. The accumulation of microcystins in mucilaginous colonies of other groups of algae poses new questions concerning the possible ecological function of these compounds and needs further study.     

A battery operated incubator for in situ primary productivity studies in small lakes and rivers

A portable, immersible incubator to measure the primary productivity of phytoplankton is described. Battery operated, inexpensive, it is designed to overcome the problem of changes in natural illumination. Tested over three years, using the ¹⁴C-technique, it is now successfully used in research work on South Wales rivers. This incubator is not submersible.     

Biological observations on freshwater systems adjacent to the coast of Sierra Leone

The Waange-Sewa basin with its extensive floodplains forms the major part of the Sherbro estuary. It is identified as one of the foremost areas for agriculture and fisheries in the southern part of Sierra Leone. Preliminary analysis on basic physico-chemistry and fish fauna of the rivers and lakes within the Waange-Sewa basin were made for the dry season and rainy season of 1983. Physico-chemical variables were used to estimate potential fish production for its river, floodplains, and lakes.     

Determination of available phosphorus for phytoplankton populations in lakes and rivers of southeastern Norway

A biotest method with diluted phytoplankton populations was used to determine external concentrations of available phosphorus in water samples with high concentrations of inorganic seston from River Rømua. RP (total molybdate reactive P measured on unfiltered samples) was approximately the P fraction available for Synedra cf. acus, Asterionella formosa and Oscillatoria agardhii. In filtered samples RP_F was the available concentration of P.The ratio RP:RP_F may give valuable information on the ratio between total available P (including available P in seston) and available P in filtered water. Different filter types may give different RP: RP_F ratios. The ratio RP:RP_F was often high during spring and autumn in River Rømua and the lakes studied. During the period June–September RP:RP_F 1 in most of the lakes and periodically in River Rømua.     

Environmental variability in the reactivity of freshwater dissolved organic carbon to UV-B

Reductions in the global stratospheric ozone layer arethought to be increasing the amount of ultraviolet B (UV-B) radiationreaching the planets surface and may be affecting the chemistry ofdissolved organic carbon (DOC) in surface waters. We studied theabundance of chromophores in DOC collected in four different aquaticenvironments in southwestern Nova Scotia using ¹³C nuclearmagnetic resonance (¹³C NMR) spectroscopy. We showed a clearseasonal pattern in the distribution of structural carbon related tolight-sensitive chromophores. There seemed to be little variation in theUV-B related chemical structure of DOC between lakes and streams, thoughwater from a bog pool showed large differences from the other samples. Thesepatterns of potential UV-B reactivity tend to be dampened however, byvariations in DOC concentrations which also occur seasonally.     

转基因植物环境监测进展

近20年来,转基因植物的商业化应用规模越来越大,而转基因生物安全问题依然是转基因植物产业进一步发展的最主要制约因素。转基因植物在商业化应用之前虽然预先进行了风险评估,但是,包括环境监测在内的风险管理措施是确保转基因植物安全应用的必要手段。在转基因作物大规模应用近20年之后,其在靶标生物抗性、对生物多样性的影响、基因漂移、在生态系统中的长期存留等方面产生的环境风险已经渐渐显现出来,表明风险评估无法为转基因植物应用提供足够的安全保障,还必须通过开展系统而长期的环境监测,明确转基因植物在生产应用后的实际环境影响。联合国环境规划署和欧盟等已经制定了转基因植物环境监测的法规和技术指南,一些国家实施了系统的转基因植物环境监测。对转基因植物所产生的环境风险以及环境监测应包括的内容进行了综述。     

Changes in quality of Finnish inland waters revealed by grouping analysis

Grouping analysis offers a fresh approach to monitoring the quality of inland water bodies. In this study it has been applied to certain parameters from a network of stations on lake deeps. General trends were sought by examining the distribution of the means for 1971–1977 among five classes created by grouping the means for 1965–1970. Marked changes in water quality are seen to have taken place, mainly in lakes whose condition was almost natural (loss of purity). These changes are indicated by differences in the distributions of the values for conductivity, alkalinity, total nitrogen and oxygen. The results suggest an increase in the importance of loading from non-point sources.     

New classification of natural breeding habitats for Neotropical anophelines in the Yanomami Indian Reserve,Amazon Region,Brazil and a new larval sampling methodology

Here we present the first in a series of articles about the ecology of immaturestages of anophelines in the Brazilian Yanomami area. We propose a new larval habitatclassification and a new larval sampling methodology. We also report some preliminaryresults illustrating the applicability of the methodology based on data collected inthe Brazilian Amazon rainforest in a longitudinal study of two remote Yanomamicommunities, Parafuri and Toototobi. In these areas, we mapped and classified 112natural breeding habitats located in low-order river systems based on theirassociation with river flood pulses, seasonality and exposure to sun. Ourclassification rendered seven types of larval habitats: lakes associated with theriver, which are subdivided into oxbow lakes and nonoxbow lakes, flooded areasassociated with the river, flooded areas not associated with the river, rainfallpools, small forest streams, medium forest streams and rivers. The methodology forlarval sampling was based on the accurate quantification of the effective breedingarea, taking into account the area of the perimeter and subtypes of microenvironmentspresent per larval habitat type using a laser range finder and a small portableinflatable boat. The new classification and new sampling methodology proposed hereinmay be useful in vector control programs.     

Possibilities and limitations of sediment traps to measure sedimentation and resuspension

Settling flux of particulate matter measured by sediment traps in shallow and turbulent waters considerably exceeds settling flux calculated from mass balances. Theoretical consideration on sinking distance and particle settling leads to the conclusion that traps overtrap particles in even moderately turbulent waters. The disappearance of turbulent diffusion and bottom shear stress within the traps causes the high rates of trapping, whereas their presence in natural water bodies hampers sedimentation.The use of sediment traps may be restricted to the identification of rapidly sinking particles, measurement of sinking velocities of well defined types of particles, and estimation of resuspension.     

The use of fish in ecological assessments

Abstract Fish provide powerful tools for assessing aquatic environments. Three attributes are especially significant: the sensitivity of fish to most forms of human disturbance, their usefulness at all levels of biological organization and the favourable benefit-to-cost ratio offish assessment programmes. Fish can be used as indicators over wide temporal and spatial ranges. Because they cover all trophic levels of consumer ecology, fish can effectively integrate the whole range of ecological processes in waterways. Fish have been used in many different roles for assessing river health and monitoring responses to remedial management. Three of these applications appear to have particular value for management of Australian rivers: (i) automated systems monitoring fish ventilation can provide sensitive, broad-spectrum and continuous sensing of water quality to protect receiving waters or water-supply intakes; (ii) programmes collecting routine data on commercial or recreational fisheries can be designed and analysed so as to isolate confounding effects due to fishery-specific factors and, hence, used to detect and monitor environmental change on large scales; (iii) the Index of Biotic Integrity (IBI) can be modified to suit Australian conditions and fish communities to meet the important need for a predictive model of aquatic environmental quality. The IBI is a quantitative biological tool with a strong ecological foundation that integrates attributes from several levels of ecosystem organization. Examples of the use of IBI elsewhere suggest its robustness, flexibility and sensitivity can cope effectively with the low diversity of the Australian fish fauna and the dominance of ecological generalists. A provisional structure is suggested for a test of the IBI in four riverine regions of New South Wales.     

Predicting diatom communities at the genus level for the rapid biological assessment of rivers

1. Diatoms were sampled in the spring of 1994 and the autumn of 1995 at 137 pristine or near-pristine reference sites on large and small streams at various altitudes in eastern New South Wales and Victoria. Scrapings were taken from five firm substrata across a range of microhabitat conditions at each site on each occasion. For each substratum, 100 valves were identified to genus level. 2. Multivariate statistical models were constructed to predict the probability of occurrence of each genus at a given site under near-pristine conditions on the basis of physical features of the site that are not affected by human activity. Model predictions were compared with the flora observed at the reference sites and at 55 test sites affected by varying degrees of human disturbance. 3. Test sites were characterized more by the presence of genera not predicted by the model than by the absence of predicted genera. The degree of departure from model predictions was related mainly to increasing alkalinity, electrical conductivity, hardness and pH of river water. We therefore conclude that the main effect of human activity on the composition of diatom communities in the rivers of coastal south-eastern Australia has been to increase genus richness through enrichment with alkaline salts. 4. The models did not perform as well as similar models applied to river macroinvertebrates at the family level, perhaps because of greater temporal variability in diatom communities and differences in the environmental variables to which diatoms and macroinvertebrates respond. Means of improving the current models are discussed.