# The Biological Assessment and Rehabilitation of the World's Rivers: An Overview
## 2 Biological Assessment of Rivers
### Asia
The use of biotic indices in national ecological monitoring programmes to detect pollution began in October 2011. Benthic invertebrates have been sampled in 47 streams and 17 reservoirs and quarry lakes. Two benthic invertebrate pollution indices have been developed primarily to assess metal pollution [78; 79]. No other biological parameters (such as algae, functional indicators or fish) are measured. In China, the Ministry of Water Resources issued in 2015 the \"Guidelines for Aquatic Ecological Protection and Restoration Planning\". This requires monitoring fish, aquatic mammals, benthic invertebrates, epiphyhic algae, phytoplankton, aquatic vascular plants, waterside vegetation, beach vegetation, amphibians, reptiles, wetland birds, and rare, endangered and endemic species. The assessment indices include predictive models and multi-metric indices but the latest is more widely used in China for both diatoms and macroinvertebrates (e.g., [83; 84]). Yet, up to now China has not conducted a national river ecological survey. From 2000 until now, a total of 122 large and small Chinese rivers were assessed through national projects (e.g., National High-Tech R&D Program, National Water Pollution Control and Treatment Science and Technology Major Project, National Key Basic Research and Development Project). Between 2008 and 2020, a long-term monitoring project was undertaken and the biological indicators included: algae (number of species, algae cell density, Shannon-Weiner Diversity Index, index of biotic integrity), macroinvertebrates (total number of taxa, EPT-Ephemeroptera, Picoptera, and Trichoptera, BMWP), and fish (fish species abundance, Shannon Winer diversity, density, IBI). There are also catchment/province-wide monitoring programs, such as that in the Yangtze River (launched in 2005, by the Yangtze River Water Resources Commission), and the Yellow River. According to the latest 2020 Yangtze River Vitality Report, the water ecology of the Yangtze River is grade B-,which means unhealthy. The ecological quality in the middle and lower reaches is poor. The existing monitoring programs have shown a serious degradation of aquatic ecosystems in several important Chinese watersheds. [PERSON] et al. [85] reported that 70 and 85 endemic Chinese fish species are threatened or endangered, respectively; and the endemic Yangtze River dolphin, Chinese sturgeon and Chinese paddlefish are functionally extinct [86]. The national implementation of river and lake monitoring would boost the application of biological elements in other Chinese hydrographic basins. Yet, there is still lack of evaluation and practical cases that reflect the regional characteristics and intercalibration exercises are needed. A pilot cooperation project supported by the European Union and Peoples' Republic of China is being developed in an attempt to adapt the WFD monitoring approach and Chinese guidelines and contribute to the design of monitoring and rehabilitation plans in China with case studies in the Haihe, Taihu and Nanxi basins. In other Asian countries, several studies have also been undertaken to investigate the use of biological indicators in the quality assessment of rivers. Using benthic invertebrates, several examples come from India, including in the Kailash Mountains of Uttarakhand state [87] and Kerala region [88; 89]. Various biotic indices were tested including SIGNAL [90] and BMWP. In Thailand, the BMWP was also applied to samples from the River Ping [91]. In addition, a new biotic index (HKHbios, Hindu Kush-Himalayan biotic score) was proposed [92] for the Hindu Kush-Himalaya region that crosses 5 countries (Banglades, Bhutan, India, Nepal and Pakistan). In Vietnam a MMI was developed for the Cau river basin [93] and a similar approach was used in Iran [94]. Diatom indices such as the TDI and IPS have been tested in the Chambal River, Central India [95] and in the Kathmandu Valley streams of Nepal and India [96].