Zhang et al.: Ecological effects of the first dam on Yangtze main stream - 2081 - ECOLOGICAL EFFECTS OF THE FIRST DAM ON YANGTZE MAIN STREAM AND FUTURE CONSERVATION RECOMMENDATIONS: A REVIEW OF THE PAST 60 YEARS ZHANG, H.1 – LI, J. Y.1 – WU, J. M.1 – WANG, C. Y.1 – DU, H.1 – WEI, Q. W.1* – KANG, M.2* 1Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture of China; Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, Hubei Province, P. R. China (phone: +86-27-8178-0118; fax: +86-27-8178-0118) 2Department of Maritime Police and Production System / The Institute of Marine Industry, Gyeongsang National University, Cheondaegukchi-Gil 38, Tongyeong-si, Gyeongsangnam-do, 53064, South Korea (phone: +82-55-772-9187; fax: +82-55-772-9189) *Corresponding authors e-mail: [email protected]; [email protected] (Received 21st Jul 2017; accepted 27th Oct 2017) Abstract. The Gezhouba Dam was the first and lowermost dam on the major stem of the Yangtze River. Up to now, the dam has been operating for more than 35 years. The time period was a fast economic development stage in the Yangtze basin. Therefore, the entire Yangtze aquatic ecosystem has been highly affected by various anthropogenic activities. Especially, the fish population and distribution in the Yangtze River have been largely altered. This study reviews the ecological effects of the Gezhouba Dam to the Yangtze aquatic biodiversity for the past 60 years based on literatures. It was concluded that the pre-assessment of the Gezhouba Dam on Yangtze fishes in 1970s was appropriate. Blocking the migration of migratory fishes, such as Chinese sturgeon Acipenser sinensis, and the four major Chinese carps, was a critical adverse effect. Currently, the Yangtze aquatic biodiversity is facing further problems not only the existence of the Gezhouba Dam but also anthropogenic activities. Effective and practical protected measures are recommended and should be conducted urgently to rescue the Yangtze aquatic biodiversity. Keywords: ecological impact assessment, anadromous fish, movement and migration, Gezhouba Dam, Yangtze River Introduction The Yangtze River originates from the Qinghai-Tibet Plateau and connects to the west Pacific. It is the third largest river in the world with more than 6,300 km in total length and 180 km2 basin area which corresponds approximately one fifth of China mainland size (Yu and Lu, 2005). It has 437 tributaries with larger than 1,000 km2 of sub-basin area and 22 of them larger than 10,000 km2. The total area of freshwater lakes is larger than 22,000 km2. The annual run off is 960×109 m3/s. Due to the huge size, the river holds high aquatic biodiversity including about 2,000 aquatic species, thereinto there are approximate 400 fish species (Yang et al., 2007). In the world, it is the only river which holds Acipenseriformes (Chinese sturgeon Acipenser sinensis, Yangtze (Dabry’s) sturgeon A. dabryanus, and Chinese paddlefish Psephurus gladius) and Cetacea (Yangtze River dolphin Lipotes vexillifer, Finless porpoise Neophocaena phoconoides). Due to high elevation variations and abundant runoff, the Yangtze River contains rich water energy. The theoretical reserve of hydraulic resources is 2.78×108 kW, and APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 15(4):2081-2097. http://www.aloki.hu ● ISSN 1589 1623 (Print) ● ISSN 1785 0037 (Online) DOI: http://dx.doi.org/10.15666/aeer/1504_20812097 2017, ALÖKI Kft., Budapest, Hungary Zhang et al.: Ecological effects of the first dam on Yangtze main stream - 2082 - the annual power generation is 2.43×1013 kWh (Yang et al., 2007). No hydropower dam on the Yangtze main stem was built until late 1960s. In 1970, the Gezhouba Dam was begun to construct and it blocked the river stream in 1981. It was the first and up to now the lowermost dam in the Yangtze main stem. It should be mentioned that at that time, as the economic difficulties and thought that a fish passage might not have worked effectively, a fish passage was decided not to be built in the end after countrywide discussions and disputes (Chang et al., 1998). For 35 years, the Gezhouba Dam has been operating and affecting Yangtze aquatic organisms in various aspects. It is speculated that the ecological effects of the dam should have already emerged. Therefore, it should be the right time to review all relevant studies on the first and lowermost dam on the Yangtze main stream. More precisely, a comprehensive review on ecological impacts on the Yangtze aquatic biodiversity on the basis of the existence of the Gezhouba Dam is needed. In this study, we review the ecological impacts of the Gezhouba Dam and the relevant Yangtze aquatic biodiversity for the past 60 years mainly based on literature studies. Furthermore, this study is to re-evaluate whether the original decisions of the Gezhouba Dam’s effects on Yangtze aquatic organisms are appropriate, and to examine how the mitigated protection measures recommended were performed. In addition, the future conservation strategies and measures are proposed and discussed on the basis of the current status of Yangtze aquatic biodiversity and threatening factors. The Yangtze aquatic biodiversity In accordance with the first systematic investigation on Yangtze fishes conducted about 60 years ago, approximately 2,000 aquatic species have been reported in the Yangtze Basin (Table 1) (Yang et al., 2007). According to the China Red Book of Endangered Animals, the number of threatened fishes was 69 species (occupied 18.25% of the entire Chinese endangered fishes), amphibian was 69 species (47.59%), and reptile was 54 species (32.53%). All had the highest threatened ratio among the China inland water areas. In addition, 162 fish species are regarded as endemic species. Many of them are listed as important protected species both inside and outside China (Table 2). Table 1. Major aquatic organisms in the Yangtze River system (Yang et al., 2007) Category Taxon Species numbers Algae Planktonic algae 321 Attached algae >100 Aquatic vascular plant Fern 6 Dicotyledon 89 Monocotyledon 119 Zooplankton Protozoa 93 Rotifer 118 Cladows 74 Copepods 45 Zoobenthos Oral gills 73 Gastropods 56 Oligochaeta 13 Polychaeta 8 APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 15(4):2081-2097. http://www.aloki.hu ● ISSN 1589 1623 (Print) ● ISSN 1785 0037 (Online) DOI: http://dx.doi.org/10.15666/aeer/1504_20812097 2017, ALÖKI Kft., Budapest, Hungary Zhang et al.: Ecological effects of the first dam on Yangtze main stream - 2083 - Aquatic insect 60 Crustacea 7 Nekton Fish 378* Mammalia 3 Amphibian and reptile Caudata 23 Anura 122 Chelonia 18 Squamata 147 Crocodilia 1 Waterfowl 129 (Poyang lake) Total >1878** * Includes 16 subspecies. ** Not includes the waterfowl and attached algae. Table 2. Protected species in the Yangtze Basin Protection level No. Chinese name English name Latin name IUCN CITES in China Yangtze River 1 白鱀豚 Lipotes vexillifer I CR I dolphin Chinese 2 白鲟 Psephurus gladius I CR II paddlefish 3 中华鲟 Chinese sturgeon Acipenser sinensis I CR II 4 达氏鲟 Dabry's sturgeon Acipenser dabryanus I CR II 5 扬子鳄 Chinese alligator Alligator sinensis I CR I Neophocaena 6 江豚 Finless porpoise II VU I phocaenoides 7 胭脂鱼 Chinese sucker Myxocyprinus asiaticus II / / 8 金线鲃 Golden line fish Sinocyclocheilus grahami II CR / Chinese giant 9 大鲵 Andrias davidianus II CR I salamander 10 川陕哲罗鲑 Sichuan taimen Hucho bleekeri II CR / Brachymystax lenok 11 秦岭细鳞鲑 Qinling lenok II / / tsinlingensis Rough-skin 12 松江鲈 Trachidermus fasciatus II / / sculpin 13 花鳗鲡 Giant mottled eel Anguilla marmorata II LC / Note: IUCN means the International Union for Conservation of Nature, CR (Critically Endangered), VU (Vulnerable) and LC (Least concern) are Red List Categories. CITES indicates the Convention on International Trade in Endangered Species of Wild Flora and Fauna, I or II means in Appendix I or II, respectively. The Gezhouba Dam and reservoir The Gezhouba Dam was located about 1,678 river km from the Yangtze estuary (river km 0 was at the estuary, Fig. 1). The Gezhouba Dam was constructed from 1970 for 20 years, blocked in 1981, and completely finished in 1990 (Anonymous, 1993; APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 15(4):2081-2097. http://www.aloki.hu ● ISSN 1589 1623 (Print) ● ISSN 1785 0037 (Online) DOI: http://dx.doi.org/10.15666/aeer/1504_20812097 2017, ALÖKI Kft., Budapest, Hungary Zhang et al.: Ecological effects of the first dam on Yangtze main stream - 2084 - CWRC, 2002). It was the largest dam since the P. R. China constructed in 1949. The dam was 2606.5 m in length, 53.8 m in height, and 70 m in elevation. The annual flow discharge at the dam was 14,300 m3/s, and sediment content was 1.19 kg/m3. The reservoir capacity was 1.58×1010 m3, and adjustable capacity was 0.8×109 m3. The total installed capacity of the power plant was 2,715 MW. The normal water level of the reservoir was 66 m. In flooded season, the length of backwater was approximately 110 km (to Badong, Hubei Province), and in dry season, the length can be up to 180 km (to Fengjie, Chongqing Municipality). Additionally, the design of the Gezhouba Dam helped in building the Three Gorges Dam, which is the biggest dam in the world, as an anti-regulated shipping cascaded dam in 1994. Yangtze Three Gorges Dam River Reservoir Huangbohe Gezhouba Dam River Yichang city Figure 1. The Gezhouba Dam and reservoir in the Yangtze River Basin APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 15(4):2081-2097. http://www.aloki.hu ● ISSN 1589 1623 (Print) ● ISSN 1785 0037 (Online) DOI: http://dx.doi.org/10.15666/aeer/1504_20812097 2017, ALÖKI Kft., Budapest, Hungary Zhang et al.: Ecological effects of the first dam on Yangtze main stream - 2085 - Impact assessment before the dam construction Before the dam was constructed, a series of special studies on fishes and fisheries in the Yangtze Basin had been conducted (FLIHHP, 1976; YARSG, 1988; Yi et al., 1988; Chen et al., 1997).