Major Chinese Carps Research Articles

Multi-scale variability of hydrothermal regime based on wavelet analysis - The middle reaches of the Yangtze River, China

Water temperature is a major driver of riverine ecosystems and has an extremely significant impact on them. Understanding the multi-scale water temperature dynamics in a river basin is critical to analyze the water temperature status of rivers. In this study, the intra-annual and inter-annual time series of water temperature (WT) at Yichang station in the middle reaches of the Yangtze River over the past 62 years was analyzed using complex Morlet wavelet functions to reveal the complex structure of water temperature variation at multiple time scales. The ecological impact of water temperature changes on the reproduction of the “Four Major Chinese Carp” under the influence of the Three Gorges Dam (TGD). The results showed that the water temperature at Yichang Station has a multi-level time scale structure, with an increasing trend at the inter-annual scale from 1956 to 2017, but different variations at the seasonal scale, and the water temperature cycles at both the inter-annual and seasonal scales have time scale variations of about 8–14 years and 4–7 years, with obvious characteristics of WT variation stages. The inter-annual and summer scales will have low WT in 2017–2022 and high WT in 2023–2027, while the other seasonal scales will have high WT in the next few years, either in the short or medium term. The correlation between air temperature and WT is the most significant among the three drivers of air temperature, flow and rainfall, and the correlation between WT and the air temperature is the most significant in winter scale under the influence of the Three Gorges Dam construction. Since the completion of TGD in 2003, the summer drainage temperature has decreased and the breeding period of the “Four Major Chinese Carp” has been shortened by 30–40 days compared to that before the construction of TGD. The results of this study can be used as a basis for further exploration of the formation mechanism of river water temperature and provide a scientific basis for river ecological protection.

Assessment of Environmental Flow Requirements for Four Major Chinese Carps in the Lower Reaches of the Jinsha River, Southwest China

An appropriate environmental flow (AEF) is one of the necessary conditions for fish spawning. The operation of cascade reservoirs in the lower reaches of the Jinsha River has changed the discharge process downstream, which in turn has directly affected the spawning habitat of fishes. Determining how to quantitatively evaluate the impact of different outflows from Xiangjiaba Reservoir on the spawning habitat of four major Chinese carp species in the downstream area is a key problem that must be solved immediately. The Yibin River section was selected as the study area, and the velocity and water depth were measured. A physical habitat simulation model (PHABSIM) was used to analyze the main hydrodynamic conditions that affect the spawning of the four major Chinese carp species and to quantify the weighted usable area (WUA) for the fishes based on different outflows from Xiangjiaba Reservoir. Hydrodynamic suitability curves for the four major Chinese carp species were established based on observed data from 2012 to 2020, and a two-dimensional hydrodynamic model was developed using a triangular grid to obtain the hydrodynamic distribution characteristics of the fish habitat. Then, the AEF range was obtained based on the outflow-WUA relationship. The results showed that the velocity during the spawning period was 0.6–1.3 m/s, the most appropriate velocity was 0.9–1.0 m/s, the water depth range was 3.0–18.0 m, and the most appropriate water depth was 9.0–12.0 m. Additionally, the AEF range was 2,000–4,500 m3/s, and the optimal AEF was, m3/s. The research results provide a scientific basis for the ecological operation of cascade reservoirs in the lower reaches of the Jinsha River.

Impact of dam construction on the spawning grounds of the four major Chinese carps in the Three Gorges Reservoir

The construction of dams has tremendously altered the water flow and environmental conditions of natural rivers, severely affecting the habitat and reproduction activities of aquatic organisms. In this study, we constructed a reproduction suitability model for the four major Chinese carps (FMCCs) in the upper reaches of the Yangtze River and related this to a one-dimensional hydrodynamic model of the Three Gorges Reservoir (TGR). Stochastic flood modelling was used to simulate a series of river floods before and after construction of the Three Gorges Dam (TGD). The simulated floods were used as the input boundaries of the hydrodynamic model to then simulate complex flow conditions in the upper reaches of the Yangtze River before and after dam construction, so as to simulate the spatial distribution and changes in the spawning grounds of the FMCCs. We found that the reproduction suitability for the FMCCs in the TGR decreased during the post-dam period, and most of the spawning grounds moved to the river reach above Zhongxian. The FMCCs were found to initially have a total of nine spawning grounds, but during the post-dam period there were six spawning grounds likely in the 60-km stretch of Zhutuo–Jiangjin section and in the 255-km stretch of Banan–Zhongxian section. By setting four different water levels in front of the dam (corresponding to no-dam, low-dam, middle-dam, and high-dam scenarios), we examined the effects of dam sizes on the spatial distribution of the FMCCs’ spawning grounds. The results showed that the area of affected spawning grounds positively correlated with the dam’s size, with high-dam scenario (corresponding to the construction of the TGD) being especially impactful through a net loss of spawning grounds extending 101 km upstream from the dam. The results of this study offer scientific guidance for the ecological regulation of the TGR.

Swimming ability of fifteen target fish from eight hydropower stations in China

近几年我国水电站过鱼设施设计已将过鱼对象游泳能力作为重要参考. 以我国8个水电站主要过鱼对象为研究目标，在野外实验设施条件下测试了15种鱼(四大家鱼组、裂腹鱼组和鳅组)的感应流速和爆发游泳速度. 采用多元线性回归法分别分析了各组鱼体长及水温对游泳能力的影响，并构建了优化的游泳能力预测模型. 结果表明，四大家鱼组、裂腹鱼组和鳅组的感应流速和爆发游速皆与体长呈负相关，感应流速与水温也皆呈负相关关系. 水温升高使四大家鱼组和裂腹鱼组的爆发游速能力增强，而水温对鳅组鱼的爆发游速影响不大，可能与鳅科鱼类特殊的腹部吸附行为有关. 利用绘制的鱼感应水流和爆发未疲劳的数量百分比的生存曲线进行上行及下行过鱼设施流速设计. 结果表明：当鱼感应水流的数量百分比为90 % 时，四大家鱼、裂腹鱼和鳅组幼鱼感应流速分别为3.00、1.67和3.22 BL/s，裂腹鱼和鳅组成鱼感应流速分别为1.27和2.09 BL/s；当鱼爆发未疲劳的数量百分比为90 % 时，四大家鱼、裂腹鱼和鳅组幼鱼爆发游泳速度分别为8.13、9.27和9.61 BL/s，裂腹鱼和鳅组成鱼爆发游泳速度分别为7.64和7.77 BL/s. 当以裂腹鱼或鳅成鱼为主要过鱼对象时，上行过鱼设施内流速范围建议为1.27~7.64和2.09~7.77 BL/s. 当以四大家鱼、裂腹鱼或鳅幼鱼为主要过鱼对象时，下行过鱼设施入口流速建议小于8.13、9.27和9.61 BL/s. 本研究结果可为我国水电站主要过鱼对象的过鱼设施设计提供参考依据.;In recent years, the design of fish passage has taken the swimming capacity of target fish as an important criterion. Fifteen fish species from eight hydropower stations in China, including the four major Chinese carp, Schizothorax and Cobitidae, were selected as target species. Swimming capability was assessed by measuring induced flow velocity (U_ind) and burst swimming speed (U_burst) under identical test conditions. The relationship between U_ind (or U_burst), water temperature (T) and body length (BL) was assessed using multiple linear regression models and the optimal prediction model of swimming capability was constructed. U_ind and U_burst were negatively related to body length, while temperature effect between U_ind and U_burst varied between the three target fish species: U_ind was negatively related to temperature; U_burst was increased with the temperature for the four major Chinese carp and Schizothorax, while the temperature had little effect on U_burst of Cobitidae, which may be related to the special abdominal adsorption behavior of this fish. The percentage of fish either induced to swim (U_ind) or that were not exhausted (U_burst) was plot using survival curves, which was used to set fish passage design criteria. The result showed that 90 % of fish induced to swim were 3.00 BL/s for juvenile four major Chinese carp, 1.67 and 1.27 BL/s for juvenile and adult Schizothorax, 3.22 and 2.09 BL/s for juvenile and adult Cobitidae, respectively. The 90 % of fish were not exhausted were 8.13 BL/s for juvenile four major Chinese carp, 9.27 and 7.64 BL/s for juvenile and adult Schizothorax, 9.61 and 7.77 BL/s for juvenile and adult Cobitidae, respectively. The recommended pool velocity range of fish passage for upper migration was 1.27-7.64 BL/s for adult Schizothorax and 2.09-7.77 BL/s for adult Cobitidae, respectively. The inlet velocity of fish passage for downstream migration was recommended to be less than 8.13, 9.27 and 9.61 BL/s for juvenile four major Chinese carp, juvenile Schizothorax and juvenile Cobitidae, respectively. The results are helpful for the design of fish passage for the main target fish of hydropower stations in China.

鄱阳湖水利枢纽工程建设对草鱼江湖洄游潜在的影响

鄱阳湖是长江四大家鱼索饵、育肥的重要场所, 近年来鄱阳湖出现了枯水季水位严重降低、枯水期延长、湿地面积缩小的现象。为解决鄱阳湖水资源、水文、水生态等问题, 建议在鄱阳湖入江水道兴建控制闸水利枢纽。然而, 拟建的水利枢纽工程将打破鄱阳湖与长江的天然连通性, 可能会对四大鱼类洄游过程产生影响。通过构建二维和三维水动力模型, 分析鄱阳湖水利枢纽建设后入江水道与枢纽洄游通道的水动力学特征, 结合实验和文献获得的草鱼幼鱼和成鱼游泳能力参数, 阐明了枢纽建设对草鱼洄游的影响。结果表明: 在设计调度模式下, 草鱼幼鱼入湖期间, 湖口段适宜通过天数达到83.74%以上, 说明湖口及入江水道的水动力条件对洄游的影响较小, 同时, 枢纽工程处在过鱼高峰期仍能保持较高的过闸效率; 草鱼成鱼出湖期间, 丰、平水年闸前水动力条件对洄游的影响较小, 仅在枯水年闸前流速几乎静止, 草鱼适宜出湖天数偏低。在该调度模式下, 水利枢纽建设运行后鄱阳湖整体水动力条件能够满足草鱼洄游需求。目前设计的鱼道在高、低水位时期均出现局部流速过大的现象, 不满足过鱼条件。从四大家鱼江湖洄游的角度为鄱阳湖水利枢纽工程设计和运行提供科学参考。;Poyang Lake serves as the main feeding and fattening venue for the four major Chinese carps. In recent years, Poyang Lake has experienced a severe drop in water level during the dry season, prolonged dry season, and reduced wetland area. To tackle the problem of water resources, hydrology and water ecology in Poyang Lake, it is suggested to build a hydro-junction project which is proposed to be located at the channel connecting the Poyang Lake and the Yangtze River. Yet the to-be-built Poyang Lake Hydro-junction Project would impede the natural connection between Poyang Lake and the Yangtze River. The migration passage of the four major Chinese carps may be affected. To study the potential impact of the prospective hydro-junction project on the migration of grass carp, analysis was conducted on the hydrodynamic characteristics of the migration channel after the construction of Poyang Lake Hydro-junction Project using two-dimensional and three-dimensional hydraulic models. The swimming ability of grass carp was determined through experiment and literature review. According to the study results, more than 83.74% of the days suitable for fish passage at the entrance to the lake. The hydrodynamic conditions at the entrance and the channel into the Yangtze River had an insignificant impact on the fish migration at the time when the juvenile grass carps entered the lake. Meanwhile, the gate chamber of hydro-junction project could still maintain a high passing efficiency during the peak period of fish migration. While under the designed scheduling mode, the hydrodynamic conditions in front of the hydraulic construction had little effect on fish migration in the years of wet and normal, but the days that were favorable for the fish departure from the lake decreased in dry years caused by almost static velocity in front of the hydraulic construction when the adult grass carps left the lake. The overall hydrodynamic conditions of Poyang Lake could meet the needs of the grass carp migration during the operation period of the Poyang Lake Hydro-junction Project. However, the current design of the fishway of the Poyang Lake Hydro-junction Project suffered the excessive flow velocity in some parts during high and low water level period, which dissatisfied the required passage conditions based on fish swimming ability under the existing scheduling mode. This study was expected to provide a scientific reference for the design and operation of the Poyang Lake Hydro-junction Project from the perspective of river-lake migration of the four major Chinese carps.

Comprehensive analysis and application of Chinese Cyprinidae swimming ability

该研究利用学术论文数据库筛选出中国鲤科鱼类游泳能力相关论文115篇，并用Origin软件进行了数据统计分析，旨在归纳和分析中国鲤科鱼类游泳能力并建立估算方法，可为正处于规划阶段和可行性研究阶段的过鱼设施流速设计提供依据.结果表明：（1）鱼类游泳速度与鱼体长度具有显著的非线性相关关系，据此建立了一系列幂函数经验公式，可为游泳能力和过鱼设施研究及设计提供依据.（2）依据所得到的经验公式和协方差分析可知，喜流水型鲤科鱼类的游泳能力>广适型>喜静水型.根据该研究得到的经验公式并结合行业规范和文献资料，对正处于规划阶段和可行性研究阶段过鱼设施流速设计的建议如下：西南地区以裂腹鱼成鱼为主要过鱼对象的过鱼设施进鱼口吸引流速范围为0.61~0.76 m/s，通道内最高流速阈值为1.28 m/s；长江中下游以四大家鱼成鱼为主要过鱼对象的进鱼口吸引流速范围为0.76~0.93 m/s，通道内最高流速阈值为1.49 m/s，以四大家鱼幼鱼为主要过鱼对象的进鱼口吸引流速范围为0.42~0.62 m/s，通道内最高流速阈值可为0.82 m/s.;In order to provide an estimation method and basis for the fish swimming ability and for the flow velocity design of fish passing facilities in the planning stage and feasibility stage, by searching the papers related to the swimming ability of Chinese Cyprinidae from the internationally recognized academic paper network database, we selected 115 and then compared them with the critical swimming speed, burst speed and total length as describing indexes by using software Origin 9.0. Results indicated:(1) The relationship between fish swimming speed and fish length is allometric rather than isometric. It is recommended that the power function can be used to fit the correlation between fish swimming speed and total length. (2) Based on the empirical formula and the covariance analysis, swimming ability of rheophilic Cyprinidae > swimming ability of semi-rheophilic Cyprinidae > swimming ability of limnophilic Cyprinidae. According to the Design code for fish passage facilities in hydropower projects in China, Guideline for fishway in water conservancy in China and literature references about fish passage facility design, as well as the empirical formula in this study, the flows for fish passing facilities in the planning and feasibility stages in southwest China and the middle and lower reaches of the Yangtze River were recommended as follows. In the southwest China, the attraction flow velocity range of the fish passing facility entrance with adult Schizothoracinae fishes as the target species is 0.61-0.76 m/s, and the maximum velocity of the passage and pool is 1.28 m/s. In the middle and lower reaches of the Yangtze River, the attraction flow velocity range of the fish passing facility entrance with adult four major Chinese carps as the target species is 0.76-0.93 m/s, and the maximum velocity of the passage and pool is 1.49 m/s. The attraction flow velocity range of the fish passing facility entrance with juvenile four major Chinese carps as the target species is 0.42-0.62 m/s, and the maximum velocity of the passage and pool is 0.82 m/s.

Join tecological operation optimal strategy of control and re-regulation reservoirs: A case study of Three Gorges-Gezhouba cascade reservoirs

全球主要河流已成为受梯级水库控制的人工调节系统.河流鱼类作为淡水生态系统的重要组成部分，在人类对河流水能资源开发利用的进程中，面临着种群退化、多样性丧失的巨大胁迫.水库生态调度是在鱼类关键生命期人为营造满足鱼类需求的水文水动力条件，减缓水库不利生态影响的一种生态环保措施.然而，在生态调度的实践过程中，受水库不同运行方式影响，下游水流条件在局部时段存在与鱼类需求相悖的情况，有进一步提升空间.本文选择了当前世界上规模最大的三峡水电站和其下游的葛洲坝水电站为案例，建立了梯级水库联合调度模型，模拟分析了梯级水库协同运行改善下游河道鱼类繁殖条件的可行性，并探讨了优化调整策略.结果表明，目前三峡、葛洲坝梯级水库生态调度的运行方式，大多数情况下仅通过葛洲坝水库小时尺度的精细调度，就可实现下游四大家鱼产卵繁殖所需的小时尺度连续涨水目标，并可一定程度提升发电出力，达到生态与经济共赢的良好成效.研究结果表明葛洲坝水库有能力在生态调度的特定时期内充分运用反调节库容调节三峡日出库流量过程，可为梯级水库生态调度的优化实践提供积极参考.;The major rivers across the world have become artificial regulation systems controlled by cascade reservoirs. River fish, as an important part of freshwater ecosystems, are under threat of population degradation and biodiversity loss in the process of development and utilization of river water energy resources. The ecological operation of the reservoir is eco-environmental protection to alleviate the negative impact on ecosystems, which artificially creates hydrological and hydrodynamic conditions to meet the requirement of fish during key life periods. However, based on ecological operation practical experience, there are circumstances where downstream flow conditions are inconsistent with the fish requirement in local periods affected by different operation conditions of reservoirs. That means the ecological operation still needs improvement. This paper takes the Three Gorges Dam, the world's largest power station, and the downstream Gezhouba Dam, as a case study, builds a joint operation model of cascade reservoirs, simulates and analyzes the feasibility of the cascade reservoirs to improve the spawning conditions of fish in the downstream river reaches under joint operation and discusses the optimal strategy. In most cases, the target of continuous flow rising for hourly timescale can be accomplished only by the hourly exquisite operation of Gezhouba reservoir, which is required for the four major Chinese carps spawning downstream of Gezhouba Dam. What's more, the hydropower generation output can be improved to a certain extent, thus achieving win-win progress of ecology and economics. The results of this paper show that Gezhouba reservoir can adjust the daily discharge process of the Three Gorges Reservoir by the re-regulation during a specific period of ecological operation, which may function as a useful reference for the optimization practice of ecological operation of cascade reservoirs.

Impact and prospects of water conservation on fish habitat and advances of ecobiology operation in Yangtze River, China: A review

Yangtze River, the longest river in Asia, provides 40 percent of freshwater in China and plays an important role in ecological biodiversity. However, this ecosystem has been deteriorated by the continuously construction of reservoirs and hydropower stations. Many investigations have been carried for the biodiversity, hydrological indicators, and species distribution along Yangtze River caused by dam construction. As a result, the ecological operation has been gradually applied to mitigate the negative effects of water conservancy projects. In order to well know recent advances in the study of fish habitat in the Yangtze River Basin, 424 original papers published from 2000 to 2020 using bibliometrics were compiled in this research to analyze the developing trends including topics, data, and research status. The results of literature statistics showed that the related research fields on the effects of the reservoir on hydrological indicators mainly focused on negative impact caused by hydrological changes, water temperature effect, and sediment variation. In the studies on the habitats of fish, the four major Chinese carps and Chinese sturgeon were the main objects of concern, in which multi-objective joint operation, cascade reservoir operation, and model coupling have been widely adapted.

Quantitative assessment of ecological operation effects based on flood pulses and ecology-economic coupling model: a case study of Three Gorges Reservoir, China

Abstract Flood pulses are closely related to river ecosystem health. Reservoirs bring many benefits to flood control, power generation, shipping etc., but their attenuation effects on runoff flood pulses should not be ignored. Ecological operation can effectively reduce some negative ecological impacts brought by the reservoir. However, the inability to quantitatively assess ecological effects hinders the promotion of ecological operation in reservoir management. To solve this problem, we proposed 11 flood pulse indicators (FPI), a random simulation method and an ecology-economy coupling model in this study. In addition, we used four major Chinese carps as indicator species and the Three Gorges Reservoir as a case study to test the role of flood pulses in improving the ecological operation effects of the reservoir from the fish protection perspective. The results show that: (1) FPI can be controlled by the reservoir and reflect the flood pulse characteristics of runoff. (2) Random simulation method guides managers to optimize the discharge and formulate eco-friendly operation schemes. (3) Ecology-economy coupling model helps managers analyze the relationship between ecological operation effects and economic benefits. A comprehensive assessment can improve the acceptance of ecological operation, which is conducive to the sustainable development of river ecosystem.

Fuzzy Representation of Environmental Flow in Multi-Objective Risk Analysis of Reservoir Operation

In the context of worldwide water shortage, environmental flow is the key to alleviating the negative environmental impact of reservoir operation. In reality, there exists a range for the stream flow suitable for the survival and reproduction of aquatic organisms. However, most of current studies set it to a fixed value, which leads to unreasonable resource allocations. In this study, we proposed a fuzzy representation of environmental flow by using the fuzzy theory and the ecological hydraulic radius. Furthermore, we used the Three Gorges-Gezhouba cascade reservoirs as a study case and Four Major Chinese Carps as indicator species. In addition, a multi-objective operation optimization model was established, which was solved by the Evolver Palisade software. Finally, a multi-objective risk analysis method was proposed based on the design reliability and risk rate of various benefit operations. The results show that: (1) Based on the environmental flow membership function, flow ranges suitable for the aquatic organism survival and reproduction at specific locations can be determined to guide reservoir discharge. (2) Taking environmental flow membership as an optimization objective rather than a constraint is conducive to formulating environmentally friendly reservoir operation schemes and making more rational use of water resources. (3) The multi-objective risk analysis can avoid the one-sidedness of single-objective risk analysis and provide more basis for reservoir management. Ecological demands have long been a factor considered when formulating reservoir operation schemes. Therefore, following the environmentally friendly operation scheme is helpful to protect the environment and maximize the overall benefits of reservoirs.

Swimming capability of target fish from eight hydropower stations in China relative to fishway design

The four major Chinese carp (MC), Schizothorax fish species (SF), and Cobitidae fish species (CF) are the most important target fish species in China. The swimming behaviour study of three target fish groups is the key to Chinese fishway designs. The 20 min critical swimming speed (Ucrit-20 min) and endurance of the target fish species in relation to body length, swimming speed, and water temperature were estimated using multiple linear regression. The results indicated that both fish body length and water temperature had a significant effect on swimming capability. Performance comparisons indicated that SF were remarkably strong swimmer. CF possess slightly greater swimming capability than MC. The entrance velocity of the upstream fishway should be greater than Ucrit-20 min, but less than maximum swimming speed to make the flow out of the fishway noticeable. The maximum swimming distance could be estimated using endurance model at flow velocity of 1.2 m·s–1. For the downstream-migrating juvenile fish, it was suggested that the flow velocity of turbine intake should be less than maximum sustained speed avoiding entering turbine.

Application of environmental DNA technology in natural reproduction of the four major Chinese carps in Yichang section of Yangtzi River, China

We explored the sample collection and DNA extraction method of environmental DNA (eDNA) technique. Droplet digital PCR (ddPCR) was used to detect the eDNA concentration of the four major Chinese carps in different water layers and different cross-sections of Yichang section of Yangtze River trunk stream. We analyzed the relationship between eDNA concentration and density of egg and fry, and explored the feasibility of using eDNA technique to monitor the natural reproduction of the four major Chinese carps. Compared with the results from traditional survey methods, the eDNA concentration of the four major Chinese carps was extremely significantly correlated with egg and fry density. The maximum concentration was consistent with the peak occurrence time of egg and fry, suggesting that eDNA technique could predict the fishcrowd behavior for spawning. The investigation of cross-section eDNA concentration during two consecutive years suggested that the range of fish spawning ground was 4.5 km upstream to 1 km downstream of Yuyangxi. The predicted spawning ground was located within the range estimated by traditional methods from the lower part of Carmine Dam to Honghua Tuo. Our results indicate that eDNA technique, as a new ecological investigation method, could more accurately determine the distribution of fish with a certain population size, and thus with a good application prospect.

Relationship between Upstream Swimming Behaviors of Juvenile Grass Carp and Characteristic Hydraulic Conditions of a Vertical Slot Fishway

The successful fish upstream movement through a dam/gate is closely associated with the hydraulic conditions of a fishway. To improve the passage efficiency, this study investigated the upstream swimming behaviors of juvenile grass carp, a representative fish of four major Chinese carps, under characteristic hydraulic conditions of a designed vertical slot fishway model. The impacts of different discharges and baffle lead angles on the successful movement of test fish were analyzed, and the selection of the movement trajectory was studied through overlay of their upstream swimming trajectories on the water flow field resulting from numerical modeling. We found that under the same discharge, the percentage of successful test fish movement with a lead angle of 45° was higher than 60° and 30°. Within a fixed lead angle, the higher the discharge, the lower the percentage of successful movement. During upstream movement, the test fish had a preferred water velocity of 0.01–0.45 m/s in the pool, and avoided areas where the turbulence kinetic energy (TKE) was greater than 0.012 m2/s2. These results provide a basis for the hydraulic design of vertical slot fishways and a reference for studying swimming behaviors of other fish species.

Combining paleolimnological proxies to understand the long-term social-ecological interactions: A case study in the Erhai basin, Southwest China

Understanding social-ecological interactions is a major research priority for sustainable management. However, the scarcity in multi-decadal records represents a big gap in information that hinders the development of above research. In this paper, we propose a framework to explore the long-term dynamic mechanisms between social and ecological systems, and present a case study in the Erhai basin, southwest China. Using paleolimnological proxies to reconstruct the long-term trends of ecological changes, the social-ecological system (SES) framework links the variations of ecosystem services (ESs) and ecosystem functions with social policies. According to the results of the Erhai basin, there were increasing social demands and wanted provisioning ESs but degraded ecosystem functions over the last 70 years. Typically, the introduction of four major Chinese carps since the 1950s, the construction of hydropower stations on the Xi'er river since the 1970s, and the development of tourism since the 1990s, have been implemented to meet the social demands for wanted fish provisioning, hydroelectricity provisioning, and culture services respectively. Although there were temporary benefits in above desired services, improper strategies have gradually impaired the functions of native fish diversity, hydrodynamic forces, and nutrient cycling. Degraded ecosystem functions threatened the sustainable provision of wanted ESs, which motivated the implementation of subsequent social policies, such as the fishing ban after the 1950s, water level control after the 1970s and restoration projects after the 1990s. By rounds of renewed social drivers/policies, the social system and ecosystem in the Erhai basin are tightly connected in the form of a feedback loop in the SES, rendering dynamic changes in wanted ESs. The current social-ecological trap in the Erhai basin emphasizes the significance of SES framework and advantages of a paleolimnological approach in revealing the long-term SES dynamics, which can help tailor proper management measures in the future.

汉江四大家鱼产卵生态水文因子分析研究

汉江四大家鱼产卵生态水文因子分析研究

Relationship between environmental variables and egg abundance of the four major Chinese carps, downstream of the Three Gorges Reservoir

AbstractReservoir “eco‐operation” is an ecological flow regulation measure, such as mimicking a flood process to stimulate fish spawning. Since 2011, the Three Gorges Reservoir (TGR) eco‐operation trials have been carried out to facilitate the spawning of the four major Chinese carps (FMCC) below the Gezhouba Dam. Until now, the response of FMCC spawning to new hydrologic conditions is seldom documented. Using ecological monitoring data from 2012 to 2017, this study analyses annual variations in environmental factors and FMCC spawning, and the correlations between them. During the date of FMCC egg occurrence, there was no significant difference both in annual mean water temperature (TEM) and water transparency (TRA) among years, while there was significant difference in annual mean river flow. The annual egg abundance of FMCC ranged from 135 to 610 million, with an average of 286 million. The peak spawning of FMCC occurred 3 to 5 times annually, while the scattered spawning occurred about 2 to 3 times. Classification and Regression Trees and Random Forests were used to model the daily egg abundance of FMCC. Daily flow (FLO) and flow increase multiple (FIM) were determined as the most important factors for FMCC spawning. The models predicted daily egg abundance of FMCC in the Shashi section could reach to 3.16 × 107 ind. for FLO exceeding 10,000 m3/s and FIM below 49.12. The results might be helpful to deeply understand the role of flood peak process on fish spawning and the optimization of TGR eco‐operation on FMCC spawning.

Advancements towards selective barrier passage by automatic species identification: applications of deep convolutional neural networks on images of dewatered fish

Abstract Invasive species negatively affect enterprises such as fisheries, agriculture, and international trade. In the Laurentian Great Lakes Basin, threats include invasive sea lamprey (Petromyzon marinus) and the four major Chinese carps. Barriers have proven to be an effective mechanism for managing invasive species but are detrimental in that they also limit the migration of desirable, native species. Fish passage technologies that selectively pass desirable species while blocking undesirable species are needed. Key to an automated selective barrier passage system is a high precision fish classifier to assign fish to be passed or blocked. Presented is an evaluation of two classifiers developed using images of partially dewatered fish captured from a commercial, high-speed camera array. For a lamprey vs. non-lamprey classification task, an ensemble prediction approach achieved near perfect accuracy on both a validation and test dataset. For a species classification task for 13 species found in the Great Lakes region, an ensemble prediction approach achieved accuracies of 96% and 97% on a validation and test dataset, respectively. Both prediction approaches were based on deep convolutional neural networks constructed using transfer learning and image augmentation. The study provides an important proof-of-concept for the viability in fully automated, selective fish passage systems.

Development of a revised method for indicators of hydrologic alteration for analyzing the cumulative impacts of cascading reservoirs on flow regime

Abstract. The impacts of reservoirs, especially multiple reservoirs, on the flow regimes and ecosystems of rivers have received increasing attention. The most widely used metrics to quantify the characteristics of flow regime alterations are the indicators of hydrologic alteration (IHAs) which include 33 parameters. Due to the difference in the degree of alteration and the intercorrelation among IHA parameters, the conventional method of evaluating IHA parameters that assigns the same weight to each indicator is obviously inadequate. A revised IHA method is proposed by utilizing the projection pursuit (PP) and real-coded accelerated genetic algorithm (RAGA). Data reliability is analyzed by using the length of record (LOR) method. The projection values reflecting the comprehensive characteristics of the evaluation parameters are calculated. Based on these methods, a scientific and reliable evaluation of the cumulative impacts of cascading reservoirs on the flow regime was made by examining the Jinsha River. The results showed that with the increase in the number of reservoirs, the alteration degrees of IHA parameters gradually increased in groups 1, 2, 3 and 4 but decreased in group 5 (each group addresses the magnitude, timing, frequency, duration and rate of change in turn), and the flow duration curves showed a declining trend at the high-flow part and an increasing trend at the low-flow part. The flow regime alteration of the outlet section was more stable than before. This change had a negative impact on downstream fish reproduction and ecological protection. An attempt at ecological regulation was made to simulate the natural rising process of water, and four major Chinese carps have a positive response to the flood peak process caused by manual regulation.

Effect of lipid on surimi gelation properties of the three major Chinese carp.

Gel properties are important in determining the quality of surimi. In addition to myofibrillar proteins, lipids play an important role in the formation of surimi gel. Phospholipids (PL) are amphoteric lipids that cannot be removed through rinsing. Paradoxically, the addition of PL increases or decreases gel strength. This research aimed to investigate the effects of specific lipids on the gelation properties of surimi from three different carp. The hardness, chewiness, and gel strength of bighead carp (Aristichthys nobilis: BC) surimi were higher, and the total lipid content was lower when compared with grass carp (Ctenopharyngodon idellus: GC) and silver carp (Hypophthalmichthys molitrix: SC) surimi. Bighead carp surimi had lower levels of phosphatidylethanolamine (PE), phosphatidylinositols (PI), and phosphatidylcholine (PC), and higher phosphatidylserine (PS) and sphingomyelin (SM) content. The gelation properties of surimi increased with increasing concentrations of SM and PS. Furthermore, increased levels of saturated fatty acids (SFAs) and decreased levels of polyunsaturated fatty acids (PUFAs) increased gelation properties. Finally, higher hydrophobic interactions and more disulfide bonds were shown to increase gel network structure stability, resulting in improving gel strength in BC surimi. The textural characteristics and gel strength of surimi were dependent on the PL content, including total lipid levels and the types of fatty acids. This may account for previous conflicting reports on PL effects on gel strength. This study provides insight into how the texture of surimi can be improved and provides a starting point for further research. © 2020 Society of Chemical Industry.

Determining the limiting water level of early flood season by combining multiobjective optimization scheduling and copula joint distribution function: A case study of three gorges reservoir

During the early flood season of the Yangtze River, which encompasses the spawning season of four major Chinese carps, reservoirs tend to remain at a low limiting water level in case of large floods. However, a low limiting water level, which is the initial water level of the spawning season, decreases the reservoir volume, causing insufficient outflow for downstream fish spawning. Therefore, the Limiting Water Level of Early Flood Season (LWLEFS) must be optimized to achieve a comprehensive benefit considering fish spawning, apart from hydropower generation and flood control. Using the Three Gorges Reservoir (TGR) as a case study, this study aims to combine multiobjective optimization scheduling using the non-dominated sorting genetic algorithm and the copula joint distribution function, and propose an optimizing framework to determine the LWLEFS. The optimizing framework is as follows: first, multiple inflow time series during the spawning season are randomly simulated based on historical hydrological wavelet analysis, to support optimization scheduling. Next, considering three objectives, i.e., hydropower generation, flood control, and fish spawning, multiobjective optimization scheduling is conducted, and the optimal individual for each inflow time series is obtained at different LWLEFSs. Subsequently, the copula joint distribution function of the three objectives is established, and the Probabilities Achieving the Established Objective Values (PAEOVs) are calculated. Additionally, the relationships between different LWLEFSs and PAEOVs are obtained, and the LWLEFS that leads to the maximum PAEOV is identified. For the TGR, the optimal LWLEFSs are 154, 149, 148, 147, and 145 m for extremely dry, generally dry, normal, generally wet, and extremely wet hydrological conditions, respectively. The optimizing framework can be extended to other reservoirs with local targets, and it offers technical support for ecological and environmental management. Plain language summaryThe fish in Yangtze River, China often spawns during June 15th to July 20th, which is located in the early flood season. In these days, the basin reservoir such as Three Gorges Reservoir always keeps a low water level for flood control. However, under the low operation water level, the reservoir volume is small and cannot release adequate water for the downstream fish spawning. The above water level needs be changed considering downstream fish spawning. Therefore, we have analyzed the multi objectives of reservoir operation, including hydropower generation, flood control and fish spawning. And we propose an optimizing framework to determine the operation water level based on their trade-off relationship. The optimizing framework is practical for ecological and environmental management, and can be applied for other reservoirs with different operation targets.