# The Biological Assessment and Rehabilitation of the World's Rivers: An Overview
###### Abstract  
The biological Assessment of the World's Rivers is an open question for the development of the world's lives. The world's lives are the most common and most common and most common and most common. The world's lives are the most common and most common. The world's lives are the most common and most common and most common. The world's lives are the most common and most common. * [24] School of Natural Resources and Environmental Studies, Karatina University, P.O. Box 1957, 10101 Karatina, Kenya; [EMAIL_ADDRESS]
* [25] Environment, Planning and Sustainable Development Directorate, 2601 Canberra, Australia; [EMAIL_ADDRESS]
* [26] Wetlands, Policy and Northern Water Use Branch, Commonwealth Environmental Water Office, 2601 Canberra, Australia; [EMAIL_ADDRESS]
* [27] Acadia University, Canada Creek, Wolfville, NS BOP 1V0, Canada; [EMAIL_ADDRESS]
* [28] Grupo de Investigacion en Biodiversidad, Medio Ambiente y Salud (BIOMAS), Facultad de Ingenierias y Ciencias Aplicadas, Ingenieria Ambiental, Universidad de Las Americas, Via Nayon S/N, 170503 Quito, Ecuador; [EMAIL_ADDRESS]
* [29] Department of Geography, Western University and Canadian Rivers Institute, London, ON N6A 5C2, Canada; [EMAIL_ADDRESS]
* [30] Correspondence: [EMAIL_ADDRESS]  
###### Abstract  
The biological assessment of rivers i.e., their assessment through use of aquatic assemblages, integrates the effects of multiple-stressors on these systems over time and is essential to evaluate ecosystem condition and establish recovery measures. It has been undertaken in many countries since the 1990s, but not globally. And where national or multi-national monitoring networks have gathered large amounts of data, the poor water body classifications have not necessarily resulted in the rehabilitation of rivers. Thus, here we aimed to identify major gaps in the biological assessment and rehabilitation of rivers worldwide by focusing on the best examples in Asia, Europe, Oceania, and North, Central, and South America. Our study showed that it is not possible so far to draw a world map of the ecological quality of rivers. Biological assessment of rivers and streams is only implemented officially nation-wide and regularly in the European Union, Japan, Republic of Korea, South Africa, and the USA. In Australia, Canada, China, New Zealand, and Singapore it has been implemented officially at the state/province level (in some cases using common protocols) or in major catchments or even only once at the national level to define reference conditions (Australia). In other cases, biological monitoring is driven by a specific problem, impact assessments, water licenses, or the need to rehabilitate a river or a river section (as in Brazil, South Korea, China, Canada, Japan, Australia). In some countries monitoring programs have only been explored by research teams mostly at the catchment or local level (e.g., Brazil, Mexico, Chile, China, India, Malaysia, Thailand, Vietnam) or implemented by citizen science groups (e.g., Southern Africa, Gambia, East Africa, Australia, Brazil, Canada). The existing large-extent assessments show a striking loss of biodiversity in the last 2-3 decades in Japanese and New Zealand rivers (e.g., 42% and 70% of fish species threatened or endangered, respectively). A poor condition (below Good condition) exists in 25% of South Korean rivers, half of the European water bodies, and 44% of USA rivers, while in Australia 30% of the reaches sampled were significantly impaired in 2006. Regarding river rehabilitation, the greatest implementation has occurred in North America, Australia, Northern Europe, Japan, Singapore, and the Republic of Korea. Most rehabilitation measures have been related to improving water quality and river connectivity for fish or the improvement of riparian vegetation. The limited extent of most rehabilitation measures (i.e., not considering the entire catchment) often constrains the improvement of biological condition.