Fish and macroinvertebrate assemblages reveal extensive degradation of the world's rivers. Issue 2 (17th October 2022)

• Record Type: Journal Article
• Authors: Feio, Maria João; Hughes, Robert M.; Serra, Sónia R. Q.; Nichols, Susan J.; Kefford, Ben J.; Lintermans, Mark; Robinson, Wayne; Odume, Oghenekaro N.; Callisto, Marcos; Macedo, Diego R.; Harding, Jon S.; Yates, Adam G.; Monk, Wendy; Nakamura, Keigo; Mori, Terutaka; Sueyoshi, Masanao; Mercado‐Silva, Norman; Chen, Kai; Baek, Min Jeong; Bae, Yeon Jae; Tachamo‐Shah, Ram Devi; Shah, Deep Narayan; Campbell, Ian; Moya, Nabor; Arimoro, Francis O.; Keke, Unique N.; Martins, Renato T.; Alves, Carlos B. M.; Pompeu, Paulo S.; Sharma, Subodh
• Is Part Of: Global change biology. Volume 29:Issue 2(2023)
• Page Start: 355
• Page End: 374
• Publication Date: 2022-10-17
• Subjects: anthropogenic degradation -- biological assessment -- climate -- human development -- human footprint -- protected areas -- streams; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.16439
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: Rivers suffer from multiple stressors acting simultaneously on their biota, but the consequences are poorly quantified at the global scale. We evaluated the biological condition of rivers globally, including the largest proportion of countries from the Global South published to date. We gathered macroinvertebrate‐ and fish‐based assessments from 72, 275 and 37, 676 sites, respectively, from 64 study regions across six continents and 45 nations. Because assessments were based on differing methods, different systems were consolidated into a 3‐class system: Good, Impaired, or Severely Impaired, following common guidelines. The proportion of sites in each class by study area was calculated and each region was assigned a Köppen‐Geiger climate type, Human Footprint score (addressing landscape alterations), Human Development Index (HDI) score (addressing social welfare), % rivers with good ambient water quality, % protected freshwater key biodiversity areas; and % of forest area net change rate. We found that 50% of macroinvertebrate sites and 42% of fish sites were in Good condition, whereas 21% and 29% were Severely Impaired, respectively. The poorest biological conditions occurred in Arid and Equatorial climates and the best conditions occurred in Snow climates. Severely Impaired conditions were associated (Pearson correlation coefficient) with higher HDI scores, poorer physico‐chemical water quality, and lower proportions of protected freshwater areas. Good biological conditions were associated with good water quality and increased forested areas. It is essential to implement statutory bioassessment programs in Asian, African, and South American countries, and continue them in Oceania, Europe, and North America. There is a need to invest in assessments based on fish, as there is less information globally and fish were strong indicators of degradation. Our study highlights a need to increase the extent and number of protected river catchments, preserve and restore natural forested areas in the catchments, treat wastewater discharges, and improve river connectivity. Abstract : The biological condition of rivers was assessed for 64 study regions of the world, based on macroinvertebrate and fish assemblages collected at 72, 275 and 37, 676 river sites, respectively. Globally, only 50% of macroinvertebrate sites and 42% of fish sites were in Good condition, whereas 21% and 29% were Severely Impaired. In some regions less than 25% of the river sites were in Good condition and more than 50% Severely impaired. In arid climates, Severely Impaired sites reach 51% for fish. Poorer biological conditions were associated with higher Human Development Index scores, poorer physico‐chemical water quality, and lower proportions of protected freshwater areas.