BIODIVERSITY MONITORING FOR AND MANAGEMENT OF FRESHWATER ECOSYSTEMS IN CHINA: A DISCUSSION AND POSITION PAPER

Due to the rapid economic growth and the continuous increase of human, ecosystem disturbances and habitat destructions, the biodiversity of freshwater ecosystems in China is rapidly declining. This issue is gradually gaining the government’s attention as its environmental policy becomes more and more equally-weighed on both “pollution prevention and control” and “ecological conservation” issues while only the former was emphasized in the past. However, some unsolved issues still exist with regard to aquatic biodiversity monitoring and management in China. For example, there are functional overlaps among governmental departments; regional ecological function divisions are not clarified; biodiversity is usually neglected or not emphasized in environmental impact assessment for construction projects; and so on. In our opinion, the following areas should be emphasied: (a) enhancing the cooperation among governmental departments; (b) setting up mechanisms to allow ecological watershed management; (c) establishing the biodiversity conservation and ecological restoration planning for local freshwater ecosystem; (d) clarifying the ecological function divisions; (e) enhancing the biodiversity monitoring and management for freshwater ecosystem in environmental impact assessment studies for industrial construction and rural development projects; (f) establishing a technical regulatory framework for related monitoring and management activities which includes an index system for monitoring and assessment; (g) studying and establishing the related biological criteria for formulating assessment standards; and (h) paying attention to aquatic vegetation, fishes, benthic macro-invertebrates and other key aquatic assemblages.

Zooplankton biodiversity monitoring in polluted freshwater ecosystems:A technical review

Freshwater ecosystems harbor a vast diversity of micro-eukaryotes(rotifers,crustaceans and protists),and such diverse taxonomic groups play important roles in ecosystem functioning and services.Unfortunately,freshwater ecosystems and biodiversity therein are threatened by many environmental stressors,particularly those derived from intensive human activities such as chemical pollution.In the past several decades,significant efforts have been devoted to halting biodiversity loss to recover services and functioning of freshwater ecosystems.Biodiversity monitoring is the first and a crucial step towards diagnosing pollution impacts on ecosystems and making conservation plans.Yet,bio-monitoring of ubiquitous micro-eukaryotes is extremely challenging,owing to many technical issues associated with micro-zooplankton such as microscopic size,fuzzy morphological features,and extremely high biodiversity.Here,we review current methods used for monitoring zooplankton biodiversity to advance management of impaired freshwater ecosystems.We discuss the development of traditional morphologybased identification methods such as scanning electron microscope(SEM)and ZOOSCAN and FlowCAM automatic systems,and DNA-based strategies such as metabarcoding and real-time quantitative PCR.In addition,we summarize advantages and disadvantages of these methods when applied for monitoring impacted ecosystems,and we propose practical DNA-based monitoring workflows for studying biological consequences of environmental pollution in freshwater ecosystems.Finally,we propose possible solutions for existing technical issues to improve accuracy and efficiency of DNA-based biodiversity monitoring.

Ecological service assessment of human-dominated freshwater ecosystem with a case study in Yangzhou Prefecture, China

Freshwater ecosystems provide a host of services to humanity. These services are now rapidly being lost, not least because of the inability of making the impacts measurable. To overcome this obstacle, assessment frameworks for freshwater ecosystem services are needed. A simple water equivalent framework to assess the ecological services provided by freshwater ecosystems was developed in this study. It translated the occupation of freshwater ecosystem services into biologically freshwater volumes and then compares this consumption to the freshwater throughput, that is, the ecological capacity available in this region. In this way, we use the example of Yangzhou Prefecture, to account the main categories of human occupation of water ecosystem services. The result showed that there is a huge gap between the consumption and the supply of freshwater ecosystem services. This must encourage local government to make land-use and water management decisions both economically rational and environmentally sound.

Effect of the Grain for Green Project on freshwater ecosystem services under drought stress

The Grain for Green Project(GGP) is an important measure for the prevention of sloping farmland and the restoration of natural vegetation.This project has been critical to the restoration of ecological environments in western China. However,the effect of the GGP on freshwater ecosystem services under extreme climates remains unclear. Thus, taking the middle and upper reaches of the Wujiang River Basin in western China as an example, this study assessed the variation of three freshwater ecosystem services(e.g., water yield, soil retention and nutrient retention) impacted by the GGP under drought stress by employing the Integrated Valuation of Ecosystem Services and Tradeoffs(In VEST) model. In addition,the trade-off/synergistic relationship between three freshwater ecosystem services was analyzed based on the Pearson correlation coefficient. As revealed from the results, the effect of the GGP on the water yield and nutrient retention under drought stress was significantly higher than that on the soil retention.With the increase in the drought degree, the variation rate of the water yield and nutrient retention impacted by the GGP increased, whereas that of the soil retention decreased. The GGP in droughts of different seasons resulted in a significant heterogeneity in the changes of three freshwater ecosystem services. The correlation coefficients between the water yield and soil retention as well as that between the water yield and the nutrient retention increased, and the correlation coefficients declined between soil and nutrient retention under different drought degrees following the GGP. Unlike for the summer drought case, there were no significant changes in the correlation coefficients between three freshwater ecosystem services in spring, autumn and winter droughts. The results suggest that the amount of farmland converted to shrubland should be regulated to reduce the trade-off intensity between freshwater ecosystem services. In addition, food security and ecological environment protection should be balanced during the implementation of the GGP, and the most concentrated distribution region of farmland-to-forest conversion will be the key area of ecological management in the future.

Which metal represents the greatest risk to freshwater ecosystem in bohai region of china?

Metals discharged from industrial effluents,agricultural wastewater,and sewage runoff by rapid urbanization are of concern as contaminants of freshwater ecosystem because of their persistence and high toxicity to aquatic organisms.This study attempted to identify which metal posed the greatest risk to freshwater ecosystem in the Bohai Region,China.The metals arsenic(As),cadmium(Cd),chromium(Cr),copper(Cu),zinc(Zn),lead(Pb),nickel(Ni),mercury(Hg),iron(Fe),and manganese(Mn)were compared against norfloxacin and gamma-hexachlorocyclohexane(lindane).By comparing the median reported environmental and ecotoxicity concentrations,it showed that Cu,Fe,Zn,Mn,and Cr were the top five metals of concern.Of these,Cu was deemed to represent the highest risk and Hg the lowest risk.The risks for all metals were higher than those for norfloxacin and lindane.Almost all the metals except Hg had water concentrations that exceeded levels where ecotoxicity effects had been recorded in the literature.A comparison with the measurements across the UK rivers suggested that all metals examined had water concentrations about 5-to 10-fold higher than the UK median values except for Cu,Fe,Cd,and Pb.The Fuyang River,a tributary of the Haihe River Basin,seemed to be the location with the highest metal concentrations.However,comparing the post-2010 period to 2000-2009,concentrations of all the metals had fallen except for Fe and Mn,so risks have decreased over the last 7 yr with the greatest improvements for Cd and Pb.While metals still pose high risks to freshwater ecosystem in this region,there is encouragement that some control measures are taken into effect.

Fairy shrimp Branchinella kugenumaensis displays sensitivity to microplastic exposure

The increasing global concern regarding plastic pollution has prompted the research into the consequences of microplastics(MPs)on aquatic ecosystems.Fairy shrimp Branchinella kugenumaensis are freshwater planktonic organisms that have existed for 250 million years.This study aimed to uncover the harmful effects of MPs,with a particular focus on their size variations(0.1,1,and 5μm),on the fairy shrimp.We focused on how MPs could significantly affect the survival and growth of fairy shrimp.Notably,larger MPs,especially those measuring 5μm,caused higher mortality rates and hindered the growth compared to smaller ones.The impact of MPs continued even subsequent to depuration in clean water.The accumulation of MPs within the intestines of fairy shrimp resulted in intestinal blockages,disrupted excretory functions,and harmed intestinal epithelial cells.Examinations at the histological,cellular,and molecular levels showed that exposure to MPs triggered necroptosis in intestinal cells,accompanied by alterations in pathways related to transcription,translation,digestion,energy metabolism,and neurological functions.Furthermore,the effects of MPs on gene expression and pathways varied based on particle size,with larger MPs having a more significant effect and causing a strong response in xenobiotic biodegradation and metabolism pathways.We suggest that the increasing severity of MPs pollution could pose a significant threat to the survival of fairy shrimp.This study provided vital insights into the complex relationship between microplastics and aquatic organisms,and highlighted the urgent need to address the potential devastating impact of plastic pollution on freshwater ecosystems.Additionally,due to their rapid growth,strong reproductive capacity,sensitivity,and ease of cultivation,fairy shrimp hold the potential candidate to serve as a model organism for studying the effects of MPs and other pollutants on freshwater ecosystems.

Stream-dwelling fungal decomposer communities along a gradient of eutrophication unraveled by 454 pyrosequencing

Microbial decomposers,especially a fungal group called aquatic hyphomycetes,play a critical role in processing plant litter in freshwaters by increasing its palatability to invertebrate shredders.Traditionally,communities of aquatic hyphomycetes have been assessed through the identification of spores,which misses non-sporulating taxa.Among new technologies,454 pyrosequencing stands out as most promising for large-scale species identification.However,very few attempts have been made to validate its effectiveness for assessing the diversity of stream-dwelling fungal communities.We attempted to gain greater insight into the diversity of aquatic fungal communities in streams exposed to various degrees of eutrophication by using the 454 pyrosequencing technology.A total of 173,889 ITS2 pyrosequencing reads with hits for fungi were obtained from the 5 investigated streams.The majority of operational taxonomic units(OTUs)belonged to Ascomycota and the identification to the genus level was achieved for 169 OTUs.Of the total,135,257 reads(ca.78%)showed close affinities to aquatic hyphomycete species.Pyrosequencing showed declining fungal diversity in the most eutrophic streams,which was congruent with a reduced diversity found through spore identification.Dominance patterns revealed by connecting representative OTUs to ITS sequences from aquatic hyphomycetes were similar to those determined by traditional spore identification techniques.However,454 pyrosequencing provided a more comprehensive view of fungal diversity;it captured almost twice as many taxa as spore counts.This study vali-dates the effectiveness of 454 pyrosequencing for surveying the diversity of stream-dwelling fungal decomposer communities.Its application may accelerate the use of these communities for monitoring the integrity of freshwaters.