Ten-year fishing ban and river ecosystem restoration in the Yangtze River

<p>Biodiversity is the immune system of river ecological health. Restoration and improvement of urban river biodiversity and return of life to river are the main goals and important tasks of river ecosystem restoration. Taking Wuyuan River located in Xiuying District, Haikou city as the research object, based on the ecological environment and biodiversity background before river restoration, the design technology and practice of Wuyuan River ecosystem restoration were discussed, and four strategies of ecological restoration were put forward: 1) River ecological restoration—Three-dimensional ecological space reconstruction. 2) Riparian ecological restoration—Flexible ecological riparian design. 3) River-wetland synergy—River-wetland complex construction. 4) Multi-functional habitat restoration—Life landscape river reconstruction. Based on the goal of biodiversity improvement, the innovative path and mode of urban river ecosystem restoration were explored from the perspective of life landscape river restoration. Finally, the biodiversity of Wuyuan River after restoration was evaluated. The results showed that the habitat types of Wuyuan River after restoration were diverse, the habitat quality was good, and the improvement effect of biodiversity was obvious. The practice of ecological restoration shows that urban river ecological restoration aimed at the improvement of biodiversity is more conducive to the overall protection of urban river ecosystem and the optimization and improvement of river landscape quality.</p>

Environmental flow (e-flow) is the water demand of one given ecosystem, which can become the flow regulation target for protection and restoration of river or estuarine ecosystems. In this study, an e-flow assessment based on the flow-ecological health index (EHI) relation model was conducted to improve ecosystem health of the Yangtze River Estuary (YRE). Monitoring data of hydrology, biology, and water environment in the last decades were used for the model establishment. For the description of the YRE ecosystem, an EHI system was developed by cumulative frequency distribution curves and adaption of national standards. After preprocessing original flow values into proportional flow values, the generalized additive model and Monte Carlo random sampling were used for the establishment of the flow-EHI relation model. From the model calculation, the e-flow assessment results were that, in proportional flow values, the suitable flow range was 1.05-1.35, and the optimum flow range was 1.15-1.25 (flows in Yangtze River Datong Station). For flow regulation in two crucial periods, flows of 42,630-65,545 m3/s or over 14,675 m3/s are needed for the suitable flow of YRE in summer (June-August) or January, respectively. An adaptive management framework of ecological health-based estuarine e-flow assessment for YRE was contrived due to the limitation of current established model when facing the extreme drought in summer, 2022. The methodology and framework in this study are expected to provide valuable management and data support for the sustainable development of estuarine ecosystems and to bring inspiration for further studies at even continental or global levels.

<em>Abstract</em>.—The Yangtze River is the largest river in China, with a drainage area encompassing a land area of 1.8 × 10<sup>6</sup> km<sup>2</sup>. The river main stem flows approximately 6,300 km from west to east through 11 provinces, eventually emptying into the East China Sea. The total basin area of the Yangtze River provides more than 40% of China’s gross domestic product, sustains nearly 500 million people, and plays a vital role in the overall socioeconomic development of China. Because of longitudinal differences in geomorphology, the Yangtze River is often divided into upper, middle, and lower reaches for the purposes of study and description. In general, the Yangtze River basin has a warm climate and abundant rainfall. The subtropical monsoon climate accounts for 70–80% of its annual rainfall, which produces predictable annual flood events during summers of each year. The Yangtze River ecosystem also has diverse aquatic habitats that support high biodiversity. The Yangtze River main stem contains more than 3,000 tributaries and approximately 4,000 lakes that provide important habitats for thousands of aquatic species, which include 378 fish species. Yet, the ecological communities of the Yangtze River have been dramatically impacted in recent decades due to high degrees of anthropogenic activities associated with the economic development of China. Significant biodiversity declines occurring throughout the basin have been largely attributed to hydropower dam construction, overexploitation of major fisheries, water pollution, and habitat fragmentation. In addition, widespread disconnection of the Yangtze River main stem from its floodplain lakes, lake reclamation projects, invasions by exotic species, and other serious ecological problems threaten the survival of the remaining aquatic resources in the basin. To offset the adverse effects of these threats, a number of nature reserves have been established. Additionally, protection and restoration measures, including spring fishing closures, artificial population enhancement strategies, and complete habitat restoration projects, have been implemented throughout the basin. Although these projects have yielded some encouraging results to date, they are still considered inadequate. It is recommended that an integrated strategy that includes cross-functional communication mechanisms, more comprehensive monitoring, ecological rehabilitation, and government legislation is still needed. This will insure that utilization and development in the Yangtze River ecosystem are sustainable and balanced with conservation and ecological needs.

A multifunctional synergy development evaluation model of the impact of the cascade reservoir construction sequence on basins

ABSTRACTEfforts at the restoration of river ecosystems are needed not only in local habitats but are also important in terrestrial regions. Large-scale assessment of human activities can be useful in integrated watershed management. In this study, we modified the Ecological Risk Index (ERI) by considering the spatial distribution of human activities in China's Haihe River Basin (HRB). The stressor factors of human activities included population, impervious surface, cattle, agricultural land use, industry, fertilizers, pesticides, water conservation facilities, and roads. A total of 423 assessment units in the HRB were created by combining watershed and administrative boundaries to analyze the spatial distribution of human activities. Two index options, the ERI (including all stressors) and the ERI-D (excluding reservoirs and sluices), were examined for different management objectives. All the stressors and both ecological risk indices (ERI and ERI-D) were ranked in four levels: low, moderate, high, and very high. Our study demonstrated that the ERI and ERI-D can provide an overview of the spatial pattern of human stressors related to river ecosystems across a large geographic region. The approach developed in this study is useful for prioritizing management actions in targeted areas.

Current knowledge about the nature and the degree of support for ecosystem restoration among residents is limited because of a lack of understanding of public attitudes and perceptions toward natural resources. Public perceptions are critical in designing and implementing any ecosystem restoration program. This study explores the relationship between public attitudes and ecosystem restoration, with a specific focus on identifying the role of place attachment in public attitudes. Using the Buriganga River of Dhaka City as a case study, the relationship between residents’ attitude towards river ecosystem restoration and the effects of various domains of place attachment on their willingness to engage in its protection and restoration are examined. This study has found that residents’ attitudes toward ecosystem restoration do vary with regard to particular measures of proximity to resources, their length of residence in the area and their depth of experience with the place. The findings of this study are useful for targeting education and awareness programs, setting priorities and in shaping policies for restoring degraded waterways.

Understanding socio-ecological characteristics associated with rivers and their catchments, and using that understanding to effectively manage and restore river ecosystems, is an increasingly complex challenge. While great strides have been made in the last half century in understanding rivers as ecological systems, human exploitation of river water and riparian zones have frustrated river management to the point that many native species are imperiled or have become extinct, invasive species are rampant, water and sediment quality are in significant decline, environmental flows are neglected, and economic pressures are placing unprecedented demands on remaining resources. At the same time, there are societal expectations that river resources be restored or rehabilitated1 to functional states, even while climate change, population growth, flow diversion, and the proliferation of chemicals impose additional burdens in ways that are not adequately understood. Therein lies one of the great challenges of this century. Can river systems be realistically restored or rehabilitated and, if so, what are the approaches and scales that have a chance of being successful? The 2013 E. Baldi lecture addresses these questions by examining 2 examples of river restoration: identifying socio-ecological attributes from those examples that have been successful as well as aspects needing improvement, and presenting principles for improving river restoration in highly complex situations. The principles are designed to enhance resilience and promote adaptive capacity within social–ecological systems—systems that continue to evolve.

Quantifying effects of hydrological and water quality disturbances on fish with food-web modeling

The river corridor is literally a spatial passage that runs along the riverbanks. The corridor’s width varies significantly depending on its intended function, land-use designation, and the associated ecological and socio-economic benefits. In this study, the river corridor is defined in terms of its role in sustaining the river ecosystem, particularly as a water source and in preserving the integrity of its hydrological substance. The primary objective of this study is to examine both the conceptual framework and the practical implementation of river corridors in promoting environmental sustainability, using the Citarum River in Indonesia as a case study. The research area covers the entire stretch of the Citarum River, from its upstream origin (km 0) to the Citarum River, Indonesia. Key parameters analyzed include river morphology, land use patterns, geospatial technology applications in land-use monitoring, anthropogenic activities, and the physical condition of the river from the thalweg (deepest channel) extending 1 km laterally on both the left and right banks. Data were collected through an integrative approach combining literature review, field observation, photographic documentation, and in-depth interviews with local residents living along the river corridor over the past two years. The study identifies both conceptual insights and implementation cases of the river corridor framework within the study period. These findings lead to the formulation of evidence-based recommendations rooted in nature-based solutions aimed at ensuring the sustainable management and restoration of river ecosystems.

Subtropical rivers in developing countries often lack adequate monitoring, which makes it difficult to comprehensively determine their water quality when faced with different anthropic impacts. There are no proper protocols in the regulations to incorporate indicators and adapt them to different biogeographic regions, limiting the potential success of conservation and restoration of river ecosystems. This study proposes implementing macroinvertebrates as bioindicators of water quality in river ecosystems, and modifying the calibration of the widely used Biomonitoring Working Party (BMWP) index for its adaptation in a subtropical river. The Duero River, Mexico, was used as an example in this study. Data were explored with multivariate statistics, and the water quality and habitat values were averaged to obtain the families’ bioindication values and the index categories. The BMWP adequately described a deterioration gradient from the origin to the river mouth (from fair to extremely polluted), with some intermediate recovery points related to the presence of springs. Its performance was compared with other biological indices and exhibited a positive relationship with all of them. In addition, how BMWP changed over time was analyzed by examining previous samples, and highlighted increased river deterioration over time. A calibrated BMWP will allow for long-term monitoring at a low cost.

Continuing degradation of river ecosystems and environmental disruption are widespread in Chinese metropolitan areas. The study on the residents’ preference for river ecosystem restoration is an essential part of assessing the environmental benefit and cost for policies implementation. A contingent valuation method is applied to estimate the public demand for urban river restoration in Hangzhou and Nanjing of the Yangtze River Delta, China. By employing an interval model, it was estimated the average individual’s willingness to pay (WTP) for urban river restoration is about 42.4 Yuan for two cities, 52.4 Yuan in Hangzhou and 35.7 Yuan in Nanjing respectively with total sample size of 1,518. It is also found that elders and households that have child or pets are willing to pay a higher amount, while households registered in locally and residents living a longer time around the river are willing to pay less. Although the public’s preferences represented differences in regions since a gap exists in natural endowments, social environment, and the relationship between people action and river (or water), the analysis indicated that some factors influencing the WTP in those two cities are similar. The results suggested that there is strong public demand for environmental improvement on urban rivers.

Understanding public support for ecosystem restoration is critical to its successful implementation because the sustainability of sound resource management is rooted in stakeholders’ support. The contingent valuation method was used to measure participants’ willingness to contribute, both in the form of money and time, to the restoration of an impaired river ecosystem. Data for this research was collected from the adult population of Dhaka City, located in the dying Buriganga River catchment. A study on the hypothetical restoration of this vulnerable urban river in Bangladesh showed that this new approach to framing the valuation questions generated greater contribution from the community. This approach was found suitable in the developing country setting where many of the participants’ ‘disposable income’ did not reflect their real earnings as the labour market was not fully monetized. This research finds strong support among residents for, and willingness to participate in, the restoration of the impaired ecosystem. The results from the logistic regression lend support to the hypothesis that a significant relationship exists between residents’ willingness to participate in restoration and their socio-demographic and perceptional characteristics. The information generated from this study will be helpful for better understanding the planning and implementation of ecosystem restoration strategies.

In The Netherlands, an integrated policy concerning the restoration of river ecosystems has been developed by the National Government. For these rehabilitation projects, TNO was asked by the Dutch government to investigate the environmental problems these project will face during realization. To reach this goal, a PC meta-information system called MIMIKRI has been developed. An example for the nature rehabilitation project “Gelderse Poort”, one of the priority projects along the Dutch rivers Rhine and Waal (Walloon) will be given.

Environmental aspects of the restoration of river ecosystems in The Netherlands

<em>Abstract</em>.—Two species of cetaceans are endemic to the Yangtze River, the baiji or Yangtze River dolphin <em>Lipotes vexillifer </em>and the Yangtze finless porpoise <em>Neophocaena asiaeorientalis asiaeorientalis</em>. Over the past several decades, both species have suffered dramatic declines in abundance and concomitant reductions in the extent of their geographic ranges. In 2006, the baiji was presumed to be extinct when an extensive survey of the Yangtze River failed to find any evidence of its continued existence. Data from that same survey further indicated that the population size of the Yangtze finless porpoises had decreased from 2,700 in 1991 to approximately 1,800 individuals by 2006. Results of a more recent population survey of the Yangtze River conducted in 2012 revealed that this rapid decline has continued, with only approximately 1,000 Yangtze finless porpoises remaining across their former range. The population viability of both species is threatened primarily by overfishing and illegal fishing of their prey, heavy boating traffic, sand dredging, construction projects in or near the water, and pollution throughout the Yangtze River ecosystem. In an attempt to protect these species, several conservation strategies, including in situ conservation (i.e., on-site conservation), ex situ conservation (i.e., off-site conservation), and captive breeding programs have been implemented. In this review, we examine the effectiveness of these conservation strategies over the past three decades and synthesize these findings to make recommendations for the future protection of the Yangtze finless porpoise.