The implementation of an environmental flow regime results in ecological recovery of regulated rivers

Environmental flows are the main restoration technique used to ameliorate the ecological effects of regulation in rivers. However, their effectiveness has yet to be unanimously accepted. This study assessed the potential ecological benefits of the application of an environmental flow regime downstream of four dams and two weirs in the Upper Nepean River system, Sydney, Australia. Aquatic macroinvertebrates in three habitat types were sampled at water‐supply and low‐flow sites and unregulated sites in 1995 and 1996, prior to the environmental flows and in 2013 and 2014, approximately 13 years following the environmental flows. The macroinvertebrate assemblage structure was significantly different between regulated and reference sites and the number of taxa lower at water‐supply sites prior to the implementation of the environmental flows. Following the environmental flows, the assemblage structure became more similar to, although still significantly different from, the unregulated sites and the number of taxa was not significantly different between regulated and unregulated sites. Thirteen or approximately 30% of taxa indicative of unregulated rivers increased in frequency at regulated sites following the environmental flows. Despite potentially similar dispersal capabilities the remainder of the taxa failed to respond the new flow regimes. The mechanisms resulting in recovery of some taxa but not others remain unclear and require further investigation as the basis of future research and monitoring. Such information and knowledge would support the application of future environmental flow regimes as the primary mechanism to ameliorate the ecological effects of river regulation.     

流域视野下梯田聚落的人居环境空间特征——以元江流域为例

针对村落人居环境研究过于注重村落本体的现状,以GIS的技术方法结合实地调研,选取梯田聚落所处的元江流域及典型样本大瓦遮河子流域为研究范围,探讨流域视野下人居环境空间的宏观与微观特征。结论如下：1）哀牢山区的崎岖山脉与密集水系造就了元江流域的格局,以水平、垂直特征奠定子流域尺度中梯田聚落的人居环境基础;2）大瓦遮河子流域的人居环境以“典型山地本底、帚状水系关联”为共性,在中低山区形成“面状森林核心、村落散布周边、旱地梯田混合”的彝族聚落区,在中山区形成“面状梯田核心、村落环绕周边、带状森林围合”的哈尼族聚落区,二者差异源自不同民族适应垂直分异效应的差异化农作策略;3）流域是人居环境研究的基本单元,超越村落本体之外的流域视野对复杂地理环境中的人居环境研究具有重要价值与普遍意义。     

Contrasting responses of intertidal microphytobenthos and phytoplankton biomass and taxonomic composition to the nutrient loads in the Jiulong River Estuary

Microphytobenthos (MPB) and phytoplankton are important primary producers in the estuarial ecosystem, and their functions are critical to the ecosystem's biodiversity and environmental safety. The aim of this study was to compare the response of MPB and phytoplankton to the nutrient loads in a eutrophic estuary, which has seldom been studied. We used high‐performance liquid chromatography (HPLC) and CHEMTAX software to examine the biomass and taxonomic composition of both MPB and phytoplankton at Da‐yu Island (DYI) and Ji‐yu Island (JYI) in the Jiulong River Estuary from July 2010 to March 2012. The results showed that MPB chlorophyll a was low in the summer and high in the winter at both DYI and JYI, indicating a unimodal pattern. However, the phytoplankton chlorophyll a showed a mirrored pattern. Diatoms were the dominant class in both benthic and pelagic environments. Although redundancy analysis indicated that the effects of different environmental factors could not be easily separated, it is likely that phosphate and temperature were the most important factors regulating the seasonal patterns of MPB and phytoplankton diatoms, respectively. MPB and phytoplankton cyanobacteria was co‐limited by salinity and temperature. The high N/P ratio and low phosphate favored chlorophytes and cyanobacteria. Our study demonstrates the use of HPLC and CHEMTAX in an integrated survey of the spatial and temporal distribution patterns of MPB and phytoplankton in an estuarial ecosystem. The contrasting responses of MPB and phytoplankton to nutrient loads indicate the critical role of MPB in subtropical estuarial ecosystem function. The relationship between nutrients and MPB may indicate a significant contribution to carbon and nutrient cycling.     

Bioaccumulation of heavy metals in Channa punctatus (Bloch) in river Ramganga (U.P.), India

Ganga is the largest riverine system of India with a fragile ecosystem. Its prone to anthropogenic disturbances because of its cultural, economic and environmental values. The contamination of river Ganga by heavy metals (HM) is due to biotic (anthropogenic sources) and abiotic (pesticides, fertilizers) sources that poses a devastating health hazard to human, plant and edible fish life. The chemical analysis with the help of atomic absorption spectrometer performed on its water samples demonstrated the accumulation of heavy metals such as Arsenic (As), Lead (Pb), Cadmium (Cd), Iron (Fe), Zinc (Zn). Moreover, the spectrophotometric analysis indicated clearly the accumulation of heavy metals in order of occurrence (Fe > As > Cd > Zn > Pb) in liver and (Zn > Fe > As > Cd > Pb) in kidney of edible fish Channa punctatus. The present study has be used to sensitively monitor the extent of heavy metals pollution in the biotic aqua life of river Ramganga system and its suggested that the bioaccumulation of heavy metal in Channa punctatus has reached above permissible limits for human consumption, indicating potential health risks. Necessary biological steps should be taken to handle such food pollution and prevent the environmental risk and food chain disruption.     

CONTAMINATED LEVEL AND RISK ASSESSMENT OF PAES IN THE UPPER REACHES OF THE YANGTZE RIVER北大核心CSCD

PAEs have been proved to be one of the major organic pollutants. The present study determined the level of PAEs using surface water samples from the upper reaches of the Yangtze River. The results showed that DEHP contributed the most to PAEs pollution, followed by DBP. Risk Quotients of PAEs were used for preliminary screening, and DEHP and BBP were identified as potential risk factors with RQ of 310 and 70.7. The MOS10 of DEHP and BBP were 1.40 and 1.32×105, respectively, indicating that BBP may pose little risk to aquatic organisms. The potential risk of DEHP was further analyzed with joint probabilistic curves. Among different biological groups, fish and zoobenthos were two major groups sensitive to DEHP-induced damage under current concentrations with 99.4% and 98.3% for 5% species of each group. While among the toxicity endpoints, reproduction may be more sensitive than others. The 5% and 10% aquatic species were suffered from reproductive damages by 100% and 97.8%, respectively. Overall, our results indicated that DEHP in the surface water of the upper Yangtze River may pose potential risk to aquatic organisms, especially on their reproduction. Therefore, more concerns should be paid in species protection and environmental management. © 2019, Institute of Hydrobiology, Chinese Academy of Sciences. All rights reserved.     

RELATIONSHIPS BETWEEN REPRODUCTION ACTIVITIES OF FISHES WITH DRIFTING EGGS AND ENVIRONMENTAL FACTORS IN THE CHISHUI RIVER北大核心CSCD

The Chishui River is the only undammed first-order tributary of the upper Yangtze River Basin. It is an important part of the “National Nature Reserve for Rare and Endemic Fishes of the Upper Yangtze River”, which plays important roles in fish conservation. To determine main environmental factors that affect the breeding activities of fishes with drifting eggs in this river, investigations on fish resources of early life stages were carried out in Chishui Reach from March to July in 2015 and April to August in 2016. A total of 27 species of fish early resources, belonging to 3 orders, 7 families and 22 genera, were collected during the investigation period. Nine of these species Pseudolaubuca engraulis, Squalidus argentatus, Gobiobotia filifer, Botia superciliaris, Parabotia fasciata, Parabotia bimaculata, Leptobotia elongate, Leptobotia taeniops and Lepturichthys fimbriata laid drifting eggs in the running water. Canonical Correspondence Analysis (CCA) revealed various breeding environmental requirements for these species. Specially, B. superciliari, P. fasciata, P. bimaculata, L. elongate, L. taeniops and L. fimbriata tended to lay eggs when the water discharge was increasing, while P. engraulis and S. argentatus showed an opposite trend. Additionally, G. filifer preformed differently between 2015 and 2016. In the low flow year, their reproductive activities were positively associated with the water discharge. However, in the high flow year, no significant relation between the reproduction activities and water discharge was observed. These results strengthen our understanding of reproductive behavior of different fish species and provide valuable insights into fish conservation. © 2019, Institute of Hydrobiology, Chinese Academy of Sciences. All rights reserved.     

ASSESSING THE CONTAMINATED LEVELS AND RISK OF TYPICAL CONTAMINANTS IN THE UPPER REACHES OF THE YANGTZE RIVER北大核心CSCD

We generally reviewed the distributions and potential risks of heavy metals, polycyclic aromatic hydrocarbons (PAHs) and phthalic acid esters (PAEs) in the upper reaches of the Yangtze River based on recent studies. The distribution of heavy metals varied significantly with locations and types of mediums, and contents of some metals exceeded the limits in food. The contents of PAHs in the upper reaches of the Yangtze River were in line with those in the lower reaches. Low molecular weight PAHs were predominant in surface water, while high molecular weight PAHs were predominant in sediments, indicating low molecular PAHs may pose greater risks to aquatic ecosystems. DEHP and DBP were the predominant monomers of PAEs in surface water and sediments, and BBP and DBP ranked first and second respectively in fish bodies. The results of risk assessment also indicated that monomers such as DBP and DnBP had greater risk than DEHP. Over all, heavy metals and organic pollutants were widely distributed in the aquatic environment in the upper reaches of the Yangtze River, which may pose potential risks to the ecosystem. © 2019, Institute of Hydrobiology, Chinese Academy of Sciences. All rights reserved.     

SPATIAL DISTRIBUTION OF ZOOPLANKTON IN THE MAIN STEM OF THE MIDDLE YANGTZE RIVER北大核心CSCD

To better understand zooplankton distribution and its relationship with the physical-chemical factors in middle Yangtze River, we collected 20 zooplankton samples from segments at Yichang, Jingzhou, Yueyang, Wuhan and Hukou in October, 2016. A total of 23 species that belong to 13 families and 14 genera were identified, among which 16 species belong to Rotifera, 4 to Copepoda and 3 to Cladocera. Among the five segments, the highest number of zooplankton species was detected at Hukou (9 species), while the lowest was at Yueyang (5 species). The average density at Wuhan (10.94±5.81) ind./L was higher than that at Hukou and the other segments. Rotifers (3.41±0.21) ind./L were dominant in the zooplanktonic community, and Keratella valga, Synchacta atylata and Keratella cochlearis were the dominant species. The average density of copepods (mainly nauplius) was (0.75±0.07) ind./L. Cladocera had the lowest average density. Similarly, the zooplankton biomass at Wuhan was also higher than that at Hukou and the other three segments. Comparing with studies at other segments of Yangtze River, we detected lower zooplankton diversity in our investigation. Spearman correlations indicated that the biomass and diversity of zooplankton were significantly and positively correlated (P<0.05) to chlorophyll a. © 2019, Institute of Hydrobiology, Chinese Academy of Sciences. All rights reserved.