River dam impacts on biogeochemical cycling


The increased use of hydropower is currently driving the greatest surge in global dam construction since the mid-20th century, meaning that most major rivers on Earth are now dammed. Dams impede the flow of essential nutrients, including carbon, phosphorus, nitrogen and silicon, along river networks, leading to enhanced nutrient transformation and elimination. Increased nutrient retention via sedimentation or gaseous elimination in dammed reservoirs influences downstream terrestrial and coastal environments. Reservoirs can also become hotspots for greenhouse gas emission, potentially impacting how ‘green’ hydropower is compared with fossil-fuel burning. In this Review, we discuss how damming changes nutrient biogeochemistry along river networks, as well as its broader environmental consequences. The influences of construction and management practices on nutrient elimination, the emission of greenhouse gases and potential remobilization of legacy nutrients are also examined. We further consider how regulating hydraulic residence time and environmental flows (or e-flows) can be used in planning and operation from dam conception to deconstruction.

Key points

  • Nutrient elimination in dam reservoirs modifies global biogeochemical cycles, with consequences to ecosystem structure and function along river networks.

  • The global importance of reservoirs as greenhouse gas sources and/or sinks remains heavily debated.

  • The reservoir hydraulic residence time can be used to develop simple relationships to predict nutrient eliminations, though small reservoirs can have large elimination efficiencies.

  • Dam-management strategies impact nutrient cycling at all phases of a dam’s life cycle, including removal.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Changes to nitrogen, phosphorus and reactive silicon fluxes along the land–ocean aquatic continuum.
Fig. 2: Elimination of nitrogen, phosphorus and silicon from reservoirs.
Fig. 3: Key nutrient processes during a reservoir life cycle.
Fig. 4: Relationships between hydraulic residence time, nutrient reactivity and elimination.
Fig. 5: Environmental flow dynamics in different flow regimes and damming scenarios.


  1. 1.

    ICOLD. Dams and the World’s Water: An Educational Book that Explains how Dams Help to Manage the World’s Water (International Commission on Large Dams, 2007).

  2. 2.

    Lehner, B. et al. High-resolution mapping of the world’s reservoirs and dams for sustainable river-flow management. Front. Ecol. Environ. 9, 494–502 (2011).

    Article  Google Scholar 

  3. 3.

    Zarfl, C., Lumsdon, A. E., Berlekamp, J., Tydecks, L. & Tockner, K. A global boom in hydropower dam construction. Aquat. Sci. 77, 161–170 (2015).

    Article  Google Scholar 

  4. 4.

    Rex, W., Foster, V., Lyon, K., Bucknall, J. & Liden, R. Supporting hydropower: an overview of the World Bank Group’s engagement. The World Bank http://documents.worldbank.org/curated/en/628221468337849536/Supporting-hydropower-an-overview-of-the-World-Bank-Groups-engagement (2014).

  5. 5.

    World Commission on Dams. Dams and Development: A New Framework for Decision-making. Report of the World Commission on Dams (Earthscan, 2000).

  6. 6.

    Yoshikawa, S., Cho, J., Yamada, H. G., Hanasaki, N. & Kanae, S. An assessment of global net irrigation water requirements from various water supply sources to sustain irrigation: rivers and reservoirs (1960–2050). Hydrol. Earth Syst. Sci. 18, 4289–4310 (2014).

    Article  Google Scholar 

  7. 7.

    REN21. Renewables 2016. Global Status Report. REN21 https://www.ren21.net/gsr-2016/ (2016).

  8. 8.

    Grill, G. et al. Mapping the world’s free-flowing rivers. Nature 569, 215–221 (2019). Quantified the changes to global river connectivity over time as the global boom in dam construction occurs.

    Article  Google Scholar 

  9. 9.

    Grill, G. et al. An index-based framework for assessing patterns and trends in river fragmentation and flow regulation by global dams at multiple scales. Environ. Res. Lett. 10, 015001 (2015).

    Article  Google Scholar 

  10. 10.

    Hermoso, V. Freshwater ecosystems could become the biggest losers of the Paris Agreement. Glob. Change Biol. 23, 3433–3436 (2017).

    Article  Google Scholar 

  11. 11.

    Grumbine, R. E. & Pandit, M. K. Threats from India’s Himalaya dams. Science 339, 36–37 (2013).

    Article  Google Scholar 

  12. 12.

    Wang, G. et al. Valuing the effects of hydropower development on watershed ecosystem services: Case studies in the Jiulong River Watershed, Fujian Province, China. Estuarine Coast. Shelf Sci. 86, 363–368 (2010).

    Article  Google Scholar 

  13. 13.

    Almeida, R. M., Barros, N., Cole, J. J., Tranvik, L. & Roland, F. Emissions from Amazonian dams. Nat. Clim. Change 3, 1005 (2013).

    Article  Google Scholar 

  14. 14.

    Kuemmerlen, M., Reichert, P., Siber, R. & Schuwirth, N. Ecological assessment of river networks: from reach to catchment scale. Sci. Total Environ. 650, 1613–1627 (2019).

    Article  Google Scholar 

  15. 15.

    Brownell Jr, R. L., Randall, R. R., Thomas, P. O., Smith, B. D. & Ryan, G. E. Dams threaten rare Mekong dolphins. Science 355, 805 (2017).

    Article  Google Scholar 

  16. 16.

    Poff, N. L. & Schmidt, J. C. How dams can go with the flow. Science 353, 1099–1100 (2016).

    Article  Google Scholar 

  17. 17.

    Poff, N. L., Olden, J. D., Merritt, D. M. & Pepin, D. M. Homogenization of regional river dynamics by dams and global biodiversity implications. Proc. Natl Acad. Sci. USA 104, 5732–5737 (2007).

    Article  Google Scholar 

  18. 18.

    Stone, R. Dam-building threatens Mekong fisheries. Science 354, 1084–1085 (2016).

    Article  Google Scholar 

  19. 19.

    Li, J. et al. Effects of damming on the biological integrity of fish assemblages in the middle Lancang-Mekong River basin. Ecol. Indic. 34, 94–102 (2013).

    Article  Google Scholar 

  20. 20.

    Ziv, G., Baran, E., Nam, S., Rodríguez-Iturbe, I. & Levin, S. A. Trading-off fish biodiversity, food security, and hydropower in the Mekong River Basin. Proc. Natl Acad. Sci. USA 109, 5609–5614 (2012).

    Article  Google Scholar 

  21. 21.

    Deemer, B. R. et al. Greenhouse gas emissions from reservoir water surfaces: a new global synthesis. BioScience 66, 949–964 (2016).

    Article  Google Scholar 

  22. 22.

    Moran, E. F., Lopez, M. C., Moore, N., Müller, N. & Hyndman, D. W. Sustainable hydropower in the 21st century. Proc. Natl Acad. Sci. USA 115, 11891–11898 (2018).

    Article  Google Scholar 

  23. 23.

    Fearnside, P. M. & Pueyo, S. Greenhouse-gas emissions from tropical dams. Nat. Clim. Change 2, 382–384 (2012).

    Article  Google Scholar 

  24. 24.

    Barros, N. et al. Carbon emission from hydroelectric reservoirs linked to reservoir age and latitude. Nat. Geosci. 4, 593–596 (2011).

    Article  Google Scholar 

  25. 25.

    Maavara, T. et al. Nitrous oxide emissions from inland waters: Are IPCC estimates too high? Glob. Change Biol. 25, 473–488 (2019).

    Article  Google Scholar 

  26. 26.

    Fearnside, P. M. Hydroelectric dams in the Brazilian Amazon as sources of ‘greenhouse’ gases. Environ. Conserv. 22, 7–19 (1995).

    Article  Google Scholar 

  27. 27.

    Kemenes, A., Forsberg, B. R. & Melack, J. M. Methane release below a tropical hydroelectric dam. Geophys. Res. Lett. https://doi.org/10.1029/2007GL029479 (2007).

  28. 28.

    Ansar, A., Flyvbjerg, B., Budzier, A. & Lunn, D. Should we build more large dams? The actual costs of hydropower megaproject development. Energy Policy 69, 43–56 (2014).

    Article  Google Scholar 

  29. 29.

    Scudder, T. The Future of Large Dams: Dealing with Social, Environmental, Institutional and Political Costs (Routledge, 2012).

  30. 30.

    Vörösmarty, C., Meybeck, M., Fekete, B. & Sharma, K. The potential impact of neo-Castorization on sediment transport by the global network of rivers. IAHS Publ. 246, 261–273 (1997).

    Google Scholar 

  31. 31.

    Vollenweider, R. A. Input-output models. Schweiz. Z. Hydrol. 37, 53–84 (1975).

    Google Scholar 

  32. 32.

    Kõiv, T., Nõges, T. & Laas, A. Phosphorus retention as a function of external loading, hydraulic turnover time, area and relative depth in 54 lakes and reservoirs. Hydrobiologia 660, 105–115 (2011).

    Article  Google Scholar 

  33. 33.

    Finlay, J. C., Small, G. E. & Sterner, R. W. Human influences on nitrogen removal in lakes. Science 342, 247–250 (2013).

    Article  Google Scholar 

  34. 34.

    Frings, P. J. et al. Lack of steady-state in the global biogeochemical Si cycle: emerging evidence from lake Si sequestration. Biogeochemistry 117, 255–277 (2014).

    Article  Google Scholar 

  35. 35.

    Lauerwald, R. et al. Natural lakes are a minor global source of N2O to the atmosphere. Glob. Biogeochem. Cycles https://doi.org/10.1029/2019GB006261 (2019).

    Article  Google Scholar 

  36. 36.

    Redfield, A. C. On the Proportions of Organic Derivatives in Sea Water and Their Relation to the Composition of Plankton James Johnstone Memorial Volume 176–192 (Univ. Press of Liverpool, 1934).

  37. 37.

    Glibert, P. M. Harmful algae at the complex nexus of eutrophication and climate change. Harmful Algae https://doi.org/10.1016/j.hal.2019.03.001 (2019).

    Article  Google Scholar 

  38. 38.

    Glibert, P. M. Ecological stoichiometry and its implications for aquatic ecosystem sustainability. Curr. Opin. Environ. Sustainability 4, 272–277 (2012).

    Article  Google Scholar 

  39. 39.

    Maavara, T. et al. Global phosphorus retention by river damming. Proc. Natl Acad. Sci. USA 112, 15603–15608 (2015).

    Article  Google Scholar 

  40. 40.

    Akbarzadeh, Z., Maavara, T., Slowinski, S. & Van Cappellen, P. Effects of damming on river nitrogen fluxes: a global analysis. Glob. Biogeochem. Cycles 33, 1339–1357 (2019).

    Article  Google Scholar 

  41. 41.

    Mayorga, E. et al. Global nutrient export from WaterSheds 2 (NEWS 2): model development and implementation. Environ. Model. Softw. 25, 837–853 (2010).

    Article  Google Scholar 

  42. 42.

    Beusen, A. H. W., Bouwman, A. F., Dürr, H. H., Dekkers, A. L. M. & Hartmann, J. Global patterns of dissolved silica export to the coastal zone: results from a spatially explicit global model. Global Biogeochem. Cycles https://doi.org/10.1029/2008GB003281 (2009).

    Article  Google Scholar 

  43. 43.

    Friedl, G. & Wüest, A. Disrupting biogeochemical cycles-consequences of damming. Aquat. Sci. 64, 55–65 (2002).

    Article  Google Scholar 

  44. 44.

    Van Cappellen, P. & Maavara, T. Rivers in the Anthropocene: global scale modifications of riverine nutrient fluxes by damming. Ecohydrol. Hydrobiol. 16, 106–111 (2016).

    Article  Google Scholar 

  45. 45.

    Vörösmarty, C. J. et al. Anthropogenic sediment retention: major global impact from registered river impoundments. Glob. Planet. Change 39, 169–190 (2003).

    Article  Google Scholar 

  46. 46.

    Hejzlar, J., Šámalová, K., Boers, P. & Kronvang, B. Modelling phosphorus retention in lakes and reservoirs. Water Air Soil. Pollut. Focus 6, 487–494 (2006).

    Article  Google Scholar 

  47. 47.

    Vörösmarty, C. J. et al. The storage and aging of continental runoff in large reservoir systems of the world. Ambio 26, 210–219 (1997).

    Google Scholar 

  48. 48.

    Paerl, H. W. et al. Controlling harmful cyanobacterial blooms in a hyper-eutrophic lake (Lake Taihu, China): the need for a dual nutrient (N & P) management strategy. Water Res. 45, 1973–1983 (2011).

    Article  Google Scholar 

  49. 49.

    North, R. L. et al. Evidence for internal phosphorus loading in a large prairie reservoir (Lake Diefenbaker, Saskatchewan). J. Gt. Lakes Res. 41, 91–99 (2015).

    Article  Google Scholar 

  50. 50.

    Donald, D. B., Parker, B. R., Davies, J.-M. & Leavitt, P. R. Nutrient sequestration in the Lake Winnipeg watershed. J. Gt. Lakes Res. 41, 630–642 (2015).

    Article  Google Scholar 

  51. 51.

    Maavara, T. et al. Reactive silicon dynamics in a large prairie reservoir (Lake Diefenbaker, Saskatchewan). J. Gt. Lakes Res. 41, 100–109 (2015).

    Article  Google Scholar 

  52. 52.

    Maranger, R., Jones, S. E. & Cotner, J. B. Stoichiometry of carbon, nitrogen, and phosphorus through the freshwater pipe. Limnol. Oceanogr. Lett. 3, 89–101 (2018). Quantified changes to nutrient ratios along the land–ocean aquatic continuum, with thorough discussion of driving mechanisms.

    Article  Google Scholar 

  53. 53.

    Brzezinski, M. A. The Si:C:N ratio of marine diatoms: interspecific variability and the effect of some environmental variables. J. Phycol. 21, 347–357 (1985).

    Article  Google Scholar 

  54. 54.

    Xu, Y., Zhang, M., Wang, L., Kong, L. & Cai, Q. Changes in water types under the regulated mode of water level in Three Gorges Reservoir, China. Quat. Int. 244, 272–279 (2011).

    Article  Google Scholar 

  55. 55.

    Huang, L., Fang, H. & Reible, D. Mathematical model for interactions and transport of phosphorus and sediment in the Three Gorges Reservoir. Water Res. 85, 393–403 (2015).

    Article  Google Scholar 

  56. 56.

    Ran, X., Yu, Z., Yao, Q., Chen, H. & Guo, H. Silica retention in the Three Gorges reservoir. Biogeochemistry 112, 209–228 (2013).

    Article  Google Scholar 

  57. 57.

    Hartmann, J., Lauerwald, R. & Moosdorf, N. A brief overview of the GLObal RIver CHemistry Database, GLORICH. Procedia Earth Planet. Sci. 10, 23–27 (2014).

    Article  Google Scholar 

  58. 58.

    Maavara, T., Dürr, H. H. & Van Cappellen, P. Worldwide retention of nutrient silicon by river damming: from sparse data set to global estimate. Glob. Biogeochem. Cycles 28, 842–855 (2014).

    Article  Google Scholar 

  59. 59.

    Egge, J. K. & Aksnes, D. L. Silicate as regulating nutrient in phytoplankton competition. Mar. Ecol. Prog. Ser. 83, 281–289 (1992).

    Article  Google Scholar 

  60. 60.

    Hall, R. I. & Smol, J. P. in The Diatoms: Applications for the Environmental and Earth Sciences (ed. Stoermer, E. F.) 128–168 (Cambridge Univ. Press, 1999).

  61. 61.

    Paerl, H. W., Valdes, L. M., Peierls, B. L., Adolf, J. E. & Harding, L. J. W. Anthropogenic and climatic influences on the eutrophication of large estuarine ecosystems. Limnol. Oceanogr. 51, 448–462 (2006).

    Article  Google Scholar 

  62. 62.

    Huisman, J. et al. Changes in turbulent mixing shift competition for light between phytoplankton species. Ecology 85, 2960–2970 (2004).

    Article  Google Scholar 

  63. 63.

    Conley, D. J. et al. Controlling eutrophication: Nitrogen and phosphorus. Science 323, 1014–1015 (2009).

    Article  Google Scholar 

  64. 64.

    Nixon, S. W. Coastal marine eutrophication: a definition, social causes, and future concerns. Ophelia 41, 199–219 (1995).

    Article  Google Scholar 

  65. 65.

    Smith, V. H., Tilman, G. D. & Nekola, J. C. Eutrophication: impacts of excess nutrient inputs on freshwater, marine, and terrestrial ecosystems. Environ. Pollut. 100, 179–196 (1999).

    Article  Google Scholar 

  66. 66.

    Justić, D., Rabalais, N. N. & Turner, R. E. Modeling the impacts of decadal changes in riverine nutrient fluxes on coastal eutrophication near the Mississippi River Delta. Ecol. Model. 152, 33–46 (2002).

    Article  Google Scholar 

  67. 67.

    Schindler, D. Evolution of phosphorus limitation in lakes. Science 195, 260–262 (1977).

    Article  Google Scholar 

  68. 68.

    Schindler, D. W. et al. Eutrophication of lakes cannot be controlled by reducing nitrogen input: results of a 37-year whole-ecosystem experiment. Proc. Natl Acad. Sci. USA 105, 11254–11258 (2008).

    Article  Google Scholar 

  69. 69.

    Howarth, R. W. & Marino, R. Nitrogen as the limiting nutrient for eutrophication in coastal marine ecosystems: evolving views over three decades. Limnol. Oceanogr. 51, 364–376 (2006).

    Article  Google Scholar 

  70. 70.

    Chaffin, J. D., Bridgeman, T. B. & Bade, D. L. Nitrogen constrains the growth of late summer cyanobacterial blooms in Lake Erie. Adv. Microbiol. 3, 16–26 (2013).

    Article  Google Scholar 

  71. 71.

    Paerl, H. W. et al. It takes two to tango: When and where dual nutrient (N & P) reductions are needed to protect lakes and downstream ecosystems. Environ. Sci. Technol. 50, 10805–10813 (2016).

    Article  Google Scholar 

  72. 72.

    Guildford, S. J. & Hecky, R. E. Total nitrogen, total phosphorus, and nutrient limitation in lakes and oceans: Is there a common relationship? Limnol. Oceanogr. 45, 1213–1223 (2000).

    Article  Google Scholar 

  73. 73.

    Nürnberg, G. K. Prediction of phosphorus release rates from total and reductant-soluble phosphorus in anoxic lake sediments. Can. J. Fish. Aquat. Sci. 45, 453–462 (1988).

    Article  Google Scholar 

  74. 74.

    Sharpley, A. et al. Phosphorus legacy: overcoming the effects of past management practices to mitigate future water quality impairment. J. Environ. Qual. 42, 1308–1326 (2013).

    Article  Google Scholar 

  75. 75.

    Maavara, T., Slowinski, S., Rezanezhad, F., Van Meter, K. & Van Cappellen, P. The role of groundwater discharge fluxes on Si:P ratios in a major tributary to Lake Erie. Sci. Total Environ. 622, 814–824 (2018).

    Article  Google Scholar 

  76. 76.

    Orihel, D. M. et al. Internal phosphorus loading in Canadian fresh waters: a critical review and data analysis. Can. J. Fish. Aquat. Sci. 74, 2005–2029 (2017).

    Article  Google Scholar 

  77. 77.

    Nixon, S. W. Replacing the Nile: are anthropogenic nutrients providing the fertility once brought to the Mediterranean by a great river? Ambio 32, 30–40 (2003).

    Article  Google Scholar 

  78. 78.

    Oczkowski, A. & Nixon, S. Increasing nutrient concentrations and the rise and fall of a coastal fishery; a review of data from the Nile Delta, Egypt. Estuar. Coast. Shelf Sci. 77, 309–319 (2008).

    Article  Google Scholar 

  79. 79.

    Turner, R. E. & Rabalais, N. N. Linking landscape and water quality in the Mississippi river basin for 200 years. Bioscience 53, 563–572 (2003).

    Article  Google Scholar 

  80. 80.

    Compton, J. et al. Variations in the global phosphorus cycle. Spec. Publ. Soc. Sediment Geol. 66, 21–33 (2000).

    Google Scholar 

  81. 81.

    Galloway, J. N. et al. Nitrogen cycles: past, present, and future. Biogeochemistry 70, 153–226 (2004).

    Article  Google Scholar 

  82. 82.

    Struyf, E. et al. Historical land use change has lowered terrestrial silica mobilization. Nat. Commun. 1, 129 (2010).

    Article  Google Scholar 

  83. 83.

    Clymans, W., Struyf, E., Govers, G., Vandevenne, F. & Conley, D. Anthropogenic impact on amorphous silica pools in temperate soils. Biogeosciences 8, 2281–2293 (2011).

    Article  Google Scholar 

  84. 84.

    Garnier, J. et al. N:P:Si nutrient export ratios and ecological consequences in coastal seas evaluated by the ICEP approach. Glob. Biogeochem. Cycles 24 https://doi.org/10.1029/2009GB003583 (2010).

    Article  Google Scholar 

  85. 85.

    Turner, R. E., Rabalais, N. N., Justic, D. & Dortch, Q. Global patterns of dissolved N, P and Si in large rivers. Biogeochemistry 64, 297–317 (2003).

    Article  Google Scholar 

  86. 86.

    Justić, D., Rabalais, N. N., Turner, R. E. & Dortch, Q. Changes in nutrient structure of river-dominated coastal waters: stoichiometric nutrient balance and its consequences. Estuarine Coast. Shelf Sci. 40, 339–356 (1995).

    Article  Google Scholar 

  87. 87.

    Billen, G. et al. in Ocean Margin Processes in Global Change Vol. 1 (eds Mantoura, R. F. C., Martin, J.-M. & Wollast, R.) 19–44 (Wiley, 1991)

  88. 88.

    Howarth, R. et al. Coupled biogeochemical cycles: eutrophication and hypoxia in temperate estuaries and coastal marine ecosystems. Front. Ecol. Environ. 9, 18–26 (2011).

    Article  Google Scholar 

  89. 89.

    Conley, D., Schelske, C. & Stoermer, E. Modification of the biogeochemical cycle of silica with eutrophication. Mar. Ecol. Prog. Ser. 101, 179–192 (1993).

    Article  Google Scholar 

  90. 90.

    Billen, G. & Garnier, J. River basin nutrient delivery to the coastal sea: Assessing its potential to sustain new production of non-siliceous algae. Mar. Chem. 106, 148–160 (2007).

    Article  Google Scholar 

  91. 91.

    Buchan, A., LeCleir, G. R., Gulvik, C. A. & González, J. M. Master recyclers: features and functions of bacteria associated with phytoplankton blooms. Nat. Rev. Microbiol. 12, 686–698 (2014).

    Article  Google Scholar 

  92. 92.

    Falkowski, P. G., Barber, R. T. & Smetacek, V. Biogeochemical controls and feedbacks on ocean primary production. Science 281, 200–206 (1998).

    Article  Google Scholar 

  93. 93.

    Tréguer, P. & Pondaven, P. Global change: Silica control of carbon dioxide. Nature 406, 358–359 (2000).

    Article  Google Scholar 

  94. 94.

    Humborg, C., Ittekkot, V., Cociasu, A. & Bodungen, B. v. Effect of Danube River dam on Black Sea biogeochemistry and ecosystem structure. Nature 386, 385–388 (1997).

    Article  Google Scholar 

  95. 95.

    Humborg, C. et al. Silicon retention in river basins: far-reaching effects on biogeochemistry and aquatic food webs in coastal marine environments. Ambio 29, 45–50 (2000).

    Article  Google Scholar 

  96. 96.

    Humborg, C. et al. Decreased silica land–sea fluxes through damming in the Baltic Sea catchment–significance of particle trapping and hydrological alterations. Biogeochemistry 77, 265–281 (2006).

    Article  Google Scholar 

  97. 97.

    Humborg, C., Smedberg, E., Medina, M. R. & Mörth, C. M. Changes in dissolved silicate loads to the Baltic Sea—The effects of lakes and reservoirs. J. Mar. Syst. 73, 223–235 (2008).

    Article  Google Scholar 

  98. 98.

    Boesch, D. F. Challenges and opportunities for science in reducing nutrient over-enrichment of coastal ecosystems. Estuaries 25, 886–900 (2002).

    Article  Google Scholar 

  99. 99.

    NRC. Clean Coastal Waters: Understanding and Reducing the Effects of Nutrient Pollution (National Academies Press, 2000).

  100. 100.

    FAO. The State of World Fisheries and Aquaculture, 2002 (United Nations Food & Agriculture Organization, 2002).

  101. 101.

    Yüksel, I. Dams and hydropower for sustainable development. Energy Sources B 4, 100–110 (2009).

    Article  Google Scholar 

  102. 102.

    Yüksel, I. Hydropower for sustainable water and energy development. Renew. Sustain. Energy Rev. 14, 462–469 (2010).

    Article  Google Scholar 

  103. 103.

    Rosa, L. P. & Schaeffer, R. Global warming potentials: the case of emissions from dams. Energy Policy 23, 149–158 (1995).

    Article  Google Scholar 

  104. 104.

    Guérin, F. et al. Methane and carbon dioxide emissions from tropical reservoirs: significance of downstream rivers. Geophys. Res. Lett. https://doi.org/10.1029/2006GL027929 (2006).

  105. 105.

    Yang, L. et al. Progress in the studies on the greenhouse gas emissions from reservoirs. Acta Ecol. Sin. 34, 204–212 (2014).

    Article  Google Scholar 

  106. 106.

    Hertwich, E. G. Addressing biogenic greenhouse gas emissions from hydropower in LCA. Environ. Sci. Technol. 47, 9604–9611 (2013).

    Article  Google Scholar 

  107. 107.

    Song, C., Gardner, K. H., Klein, S. J., Souza, S. P. & Mo, W. Cradle-to-grave greenhouse gas emissions from dams in the United States of America. Renew. Sustain. Energy Rev. 90, 945–956 (2018).

    Article  Google Scholar 

  108. 108.

    Muller, M. Hydropower dams can help mitigate the global warming impact of wetlands. Nature 566, 315–317 (2019).

    Article  Google Scholar 

  109. 109.

    Matthews, J. H. Dam development: value both wetlands and hydropower. Nature 568, 33 (2019).

    Article  Google Scholar 

  110. 110.

    Prairie, Y. T. et al. Greenhouse gas emissions from freshwater reservoirs: what does the atmosphere see? Ecosystems 21, 1058–1071 (2018). A comprehensive discussion of the uncertainties associated with predicting the net impacts of dam reservoirs on global greenhouse gas emissions.

    Article  Google Scholar 

  111. 111.

    Hu, Y. & Cheng, H. The urgency of assessing the greenhouse gas budgets of hydroelectric reservoirs in China. Nat. Clim. Change 3, 708–712 (2013).

    Article  Google Scholar 

  112. 112.

    Galy-Lacaux, C., Delmas, R., Kouadio, G., Richard, S. & Gosse, P. Long-term greenhouse gas emissions from hydroelectric reservoirs in tropical forest regions. Glob. Biogeochem. Cycles 13, 503–517 (1999).

    Article  Google Scholar 

  113. 113.

    Mendonça, R. et al. Hydroelectric carbon sequestration. Nat. Geosci. 5, 838–840 (2012).

    Article  Google Scholar 

  114. 114.

    Maavara, T., Lauerwald, R., Regnier, P. & Van Cappellen, P. Global perturbation of organic carbon cycling by river damming. Nat. Commun. 8, 15347 (2017).

    Article  Google Scholar 

  115. 115.

    Fearnside, P. M. Do hydroelectric dams mitigate global warming? The case of Brazil’s Curuá-Una Dam. Mitig. Adapt. Strateg. Glob. Change 10, 675–691 (2005).

    Article  Google Scholar 

  116. 116.

    Fearnside, P. M. Greenhouse-gas emissions from Amazonian hydroelectric reservoirs: the example of Brazil’s Tucuruí Dam as compared to fossil fuel alternatives. Environ. Conserv. 24, 64–75 (1997).

    Article  Google Scholar 

  117. 117.

    St. Louis, V. L., Kelly, C. A., Duchemin, É., Rudd, J. W. & Rosenberg, D. M. Reservoir surfaces as sources of greenhouse gases to the atmosphere: a global estimate: reservoirs are sources of greenhouse gases to the atmosphere, and their surface areas have increased to the point where they should be included in global inventories of anthropogenic emissions of greenhouse gases. BioScience 50, 766–775 (2000).

    Article  Google Scholar 

  118. 118.

    Mendonça, R. et al. Organic carbon burial in global lakes and reservoirs. Nat. Commun. 8, 1694 (2017).

    Article  Google Scholar 

  119. 119.

    Cole, J. J. et al. Plumbing the global carbon cycle: integrating inland waters into the terrestrial carbon budget. Ecosystems 10, 172–185 (2007). Landmark paper that develops the framework for including the land–ocean aquatic continuum in global carbon budgets.

    Article  Google Scholar 

  120. 120.

    Dean, W. E. & Gorham, E. Magnitude and significance of carbon burial in lakes, reservoirs, and peatlands. Geology 26, 535–538 (1998).

    Article  Google Scholar 

  121. 121.

    Mulholland, P. J. & Elwood, J. W. The role of lake and reservoir sediments as sinks in the perturbed global carbon cycle. Tellus 34, 490–499 (1982).

    Google Scholar 

  122. 122.

    Stallard, R. F. Terrestrial sedimentation and the carbon cycle: coupling weathering and erosion to carbon burial. Glob. Biogeochem. Cycles 12, 231–257 (1998).

    Article  Google Scholar 

  123. 123.

    Li, Z. et al. Carbon footprints of pre-impoundment clearance on reservoir flooded area in China’s large hydro-projects: Implications for GHG emissions reduction in the hydropower industry. J. Clean. Prod. 168, 1413–1424 (2017).

    Article  Google Scholar 

  124. 124.

    Zheng, H. et al. Spatial–temporal variations of methane emissions from the Ertan hydroelectric reservoir in southwest China. Hydrol. Process. 25, 1391–1396 (2011).

    Article  Google Scholar 

  125. 125.

    Lu, F. et al. Preliminary report on methane emissions from the Three Gorges Reservoir in the summer drainage period. J. Environ. Sci. 23, 2029–2033 (2011).

    Article  Google Scholar 

  126. 126.

    Rosa, L. P., Dos Santos, M. A., Matvienko, B., dos Santos, E. O. & Sikar, E. Greenhouse gas emissions from hydroelectric reservoirs in tropical regions. Climatic Change 66, 9–21 (2004).

    Article  Google Scholar 

  127. 127.

    Shi, W. et al. Carbon emission from cascade reservoirs: spatial heterogeneity and mechanisms. Environ. Sci. Technol. 51, 12175–12181 (2017).

    Article  Google Scholar 

  128. 128.

    Zhao, Y., Wu, B. & Zeng, Y. Spatial and temporal patterns of greenhouse gas emissions from Three Gorges Reservoir of China. Biogeosciences 10, 1219–1230 (2013).

    Article  Google Scholar 

  129. 129.

    Dos Santos, M. A., Rosa, L. P., Sikar, B., Sikar, E. & Dos Santos, E. O. Gross greenhouse gas fluxes from hydro-power reservoir compared to thermo-power plants. Energy Policy 34, 481–488 (2006).

    Article  Google Scholar 

  130. 130.

    De Faria, F. A., Jaramillo, P., Sawakuchi, H. O., Richey, J. E. & Barros, N. Estimating greenhouse gas emissions from future Amazonian hydroelectric reservoirs. Environ. Res. Lett. 10, 124019 (2015).

    Article  Google Scholar 

  131. 131.

    Garnier, J. & Billen, G. Production vs. respiration in river systems: an indicator of an “ecological status”. Sci. Total Environ. 375, 110–124 (2007).

    Article  Google Scholar 

  132. 132.

    Wang, F., Wang, Y., Zhang, J., Xu, H. & Wei, X. Human impact on the historical change of CO2 degassing flux in River Changjiang. Geochem. Trans. 8, 7 (2007).

    Article  Google Scholar 

  133. 133.

    Jones Jr, J. B., Stanley, E. H. & Mulholland, P. J. Long-term decline in carbon dioxide supersaturation in rivers across the contiguous United States. Geophys. Res. Lett. https://doi.org/10.1029/2003GL017056 (2003).

    Article  Google Scholar 

  134. 134.

    Beaulieu, J. J. et al. Nitrous oxide emission from denitrification in stream and river networks. Proc. Natl Acad. Sci. USA 108, 214–219 (2011).

    Article  Google Scholar 

  135. 135.

    Messager, M. L., Lehner, B., Grill, G., Nedeva, I. & Schmitt, O. Estimating the volume and age of water stored in global lakes using a geo-statistical approach. Nat. Commun. 7, 13603 (2016).

    Article  Google Scholar 

  136. 136.

    Giles, J. Methane quashes green credentials of hydropower. Nature 444, 524 (2006).

    Google Scholar 

  137. 137.

    Abril, G. et al. Carbon dioxide and methane emissions and the carbon budget of a 10-year old tropical reservoir (Petit Saut, French Guiana). Glob. Biogeochem. Cycles https://doi.org/10.1029/2005GB002457 (2005).

    Article  Google Scholar 

  138. 138.

    Chen, H. et al. Methane emissions from newly created marshes in the drawdown area of the Three Gorges Reservoir. J. Geophys. Res. https://doi.org/10.1029/2009JD012410 (2009).

  139. 139.

    Pacca, S. Impacts from decommissioning of hydroelectric dams: a life cycle perspective. Climatic Change 84, 281–294 (2007).

    Article  Google Scholar 

  140. 140.

    Almeida, R. M. et al. Reducing greenhouse gas emissions of Amazon hydropower with strategic dam planning. Nat. Commun. 10, 1–9 (2019).

    Article  Google Scholar 

  141. 141.

    Catalán, N., Marcé, R., Kothawala, D. N. & Tranvik, L. J. Organic carbon decomposition rates controlled by water retention time across inland waters. Nat. Geosci. 9, 501–504 (2016). Compilation of field and laboratory measurements of organic carbon decomposition shows that small water bodies with shorter hydraulic residence times have higher degradation than larger water bodies.

    Article  Google Scholar 

  142. 142.

    Cheng, F. Y. & Basu, N. B. Biogeochemical hotspots: role of small water bodies in landscape nutrient processing. Water Resour. Res. 53, 5038–5056 (2017).

    Article  Google Scholar 

  143. 143.

    Botter, G., Basu, N. B., Zanardo, S., Rao, P. S. C. & Rinaldo, A. Stochastic modeling of nutrient losses in streams: Interactions of climatic, hydrologic, and biogeochemical controls. Water Resour. Res. https://doi.org/10.1029/2009WR008758 (2010).

  144. 144.

    Lehner, B. et al. High-resolution mapping of the world’s reservoirs and dams for sustainable river-flow management. Front. Ecol. Environ. 9, 494–502 (2011).

    Article  Google Scholar 

  145. 145.

    Mulligan, M., Saenz-Cruz, L., van Soesbergen, A., Smith, V. T. & Zurita, L. Global dams database and geowiki. Version 1. http://geodata.policysupport.org/dams (2009).

  146. 146.

    Lehner, B., Verdin, K. & Jarvis, A. HydroSHEDS technical documentation, version 1.0. HydroSHEDS https://hydrosheds.cr.usgs.gov/webappcontent/HydroSHEDS_TechDoc_v10.pdf (2006).

  147. 147.

    Harrison, J. A., Frings, P. J., Beusen, A. H. W., Conley, D. J. & McCrackin, M. L. Global importance, patterns, and controls of dissolved silica retention in lakes and reservoirs. Glob. Biogeochem. Cycles https://doi.org/10.1029/2011GB004228 (2012).

    Article  Google Scholar 

  148. 148.

    Harrison, J. A. et al. The regional and global significance of nitrogen removal in lakes and reservoirs. Biogeochemistry 93, 143–157 (2009).

    Article  Google Scholar 

  149. 149.

    Downing, J. A. et al. The global abundance and size distribution of lakes, ponds, and impoundments. Limnol. Oceanogr. 51, 2388–2397 (2006).

    Article  Google Scholar 

  150. 150.

    Habets, F., Molénat, J., Carluer, N., Douez, O. & Leenhardt, D. The cumulative impacts of small reservoirs on hydrology: a review. Sci. Total Environ. 643, 850–867 (2018).

    Article  Google Scholar 

  151. 151.

    Benndorf, J. & Pütz, K. Control of eutrophication of lakes and reservoirs by means of pre-dams—I. Mode of operation and calculation of the nutrient elimination capacity. Water Res. 21, 829–838 (1987).

    Article  Google Scholar 

  152. 152.

    Pütz, K. & Benndorf, J. The importance of pre-reservoirs for the control of eutrophication of reservoirs. Water Sci. Technol. 37, 317–324 (1998).

    Article  Google Scholar 

  153. 153.

    Petts, G. E. Water allocation to protect river ecosystems. Regul. Rivers Res. Manag. 12, 353–365 (1996).

    Article  Google Scholar 

  154. 154.

    Arthington, A. H., Bunn, S. E., Poff, N. L. & Naiman, R. J. The challenge of providing environmental flow rules to sustain river ecosystems. Ecol. Appl. 16, 1311–1318 (2006).

    Article  Google Scholar 

  155. 155.

    Chen, W. & Olden, J. D. Evaluating transferability of flow–ecology relationships across space, time and taxonomy. Freshw. Biol. 63, 817–830 (2018).

    Article  Google Scholar 

  156. 156.

    Acreman, M. et al. Environmental flows for natural, hybrid, and novel riverine ecosystems in a changing world. Front. Ecol. Environ. 12, 466–473 (2014).

    Article  Google Scholar 

  157. 157.

    Tharme, R. E. A global perspective on environmental flow assessment: emerging trends in the development and application of environmental flow methodologies for rivers. River Res. Appl. 19, 397–441 (2003).

    Article  Google Scholar 

  158. 158.

    Acreman, M. Environmental flows—basics for novices. Wiley Interdiscip. Rev. Water 3, 622–628 (2016).

    Article  Google Scholar 

  159. 159.

    Gillespie, B. R., Desmet, S., Kay, P., Tillotson, M. R. & Brown, L. E. A critical analysis of regulated river ecosystem responses to managed environmental flows from reservoirs. Freshw. Biol. 60, 410–425 (2015).

    Article  Google Scholar 

  160. 160.

    Huang, Z. & Wang, L. Yangtze dams increasingly threaten the survival of the Chinese sturgeon. Curr. Biol. 28, 3640–3647.e18 (2018).

    Article  Google Scholar 

  161. 161.

    Robinson, C. T., Siebers, A. R. & Ortlepp, J. Long-term ecological responses of the River Spöl to experimental floods. Freshw. Sci. 37, 433–447 (2018).

    Article  Google Scholar 

  162. 162.

    Sertić Perić, M., Jolidon, C., Uehlinger, U. & Robinson, C. T. Long-term ecological patterns of alpine streams: an imprint of glacial legacies. Limnol. Oceanogr. 60, 992–1007 (2015).

    Article  Google Scholar 

  163. 163.

    Tennant, D. L. Instream flow regimens for fish, wildlife, recreation and related environmental resources. Fisheries 1, 6–10 (1976).

    Article  Google Scholar 

  164. 164.

    Smakhtin, V. U., Shilpakar, R. L. & Hughes, D. A. Hydrology-based assessment of environmental flows: an example from Nepal. Hydrolog. Sci. J. 51, 207–222 (2006).

    Article  Google Scholar 

  165. 165.

    Kim, S. M. & Kim, D. H. in International Conference of Agricultural Engineering (Zurich, 2014).

  166. 166.

    Rahi, K. A. & Halihan, T. Changes in the salinity of the Euphrates River system in Iraq. Regional Environ. Change 10, 27–35 (2010).

    Article  Google Scholar 

  167. 167.

    Huisman, J. et al. Cyanobacterial blooms. Nat. Rev. Microbiol. 16, 471–483 (2018).

    Article  Google Scholar 

  168. 168.

    Ashby, S. L., Myers, J. L., Laney, E., Honnell, D. & Owens, C. The effects of hydropower releases from Lake Texoma on downstream water quality. J. Freshw. Ecol. 14, 103–112 (1999).

    Article  Google Scholar 

  169. 169.

    Nürnberg, G. K. Lake responses to long-term hypolimnetic withdrawal treatments. Lake Reserv. Manag. 23, 388–409 (2007).

    Article  Google Scholar 

  170. 170.

    Sabo, J. et al. Designing river flows to improve food security futures in the lower Mekong Basin. Science 358, eaao1053 (2017).

    Article  Google Scholar 

  171. 171.

    O’Connor, J. E., Duda, J. J. & Grant, G. E. 1000 dams down and counting. Science 348, 496–497 (2015).

    Article  Google Scholar 

  172. 172.

    Pohl, M. M. Bringing down our dams: Trends in American dam removal rationales. J. Am. Water Resour. Assoc. 38, 1511–1519 (2002).

    Article  Google Scholar 

  173. 173.

    Bellmore, J. R. et al. Status and trends of dam removal research in the United States. Wiley Interdiscip. Rev. Water 4, e1164 (2017).

    Article  Google Scholar 

  174. 174.

    Stanley, E. H. & Doyle, M. W. Trading off: the ecological effects of dam removal. Front. Ecol. Environ. 1, 15–22 (2003). Comprehensive review of the broad impacts of dam removal on biogeochemical cycling and river ecosystem health.

    Article  Google Scholar 

  175. 175.

    Van Meter, K. J., Van Cappellen, P. & Basu, N. B. Legacy nitrogen may prevent achievement of water quality goals in the Gulf of Mexico. Science 360, 427–430 (2018). Modelled historical and predicted future nitrogen loads for the Mississippi River, indicating that legacy nitrogen loading from agriculture may prevent reduction of the Gulf of Mexico dead zone for decades.

    Article  Google Scholar 

  176. 176.

    Shuman, J. R. Environmental considerations for assessing dam removal alternatives for river restoration. Regul. Rivers Res. Manag. 11, 249–261 (1995).

    Article  Google Scholar 

  177. 177.

    Islam, M. S., Bonner, J. S., Fuller, C. S. & Kirkey, W. Impacts of an extreme weather-related episodic event on the Hudson river and estuary. Environ. Eng. Sci. 33, 270–282 (2016).

    Article  Google Scholar 

  178. 178.

    Chateauvert, A., Linnansaari, T., Yamazaki, G. & Curry, R. A. Environmental Considerations for Large Dam Removals (Canadian Rivers Insitute, University of New Brunswick, 2015).

  179. 179.

    Gray, L. J. & Ward, J. V. Effects of sediment releases from a reservoir on stream macroinvertebrates. Hydrobiologia 96, 177–184 (1982).

    Article  Google Scholar 

  180. 180.

    Perrin, C., Ashley, K. & Larkin, G. Effect of drawdown on ammonium and iron concentrations in a coastal mountain reservoir. Water Qual. Res. J. 35, 231–244 (2000).

    Article  Google Scholar 

  181. 181.

    Bohrerova, Z., Park, E., Halloran, K. & Lee, J. Water quality changes shortly after low-head dam removal examined with cultural and microbial source tracking methods. River Res. Appl. 33, 113–122 (2017).

    Article  Google Scholar 

  182. 182.

    Simon, A. & Darby, S. E. Process-form interactions in unstable sand-bed river channels: A numerical modeling approach. Geomorphology 21, 85–106 (1997).

    Article  Google Scholar 

  183. 183.

    Walter, R. C. & Merritts, D. J. Natural streams and the legacy of water-powered mills. Science 319, 299–304 (2008).

    Article  Google Scholar 

  184. 184.

    Stanley, E. H. & Doyle, M. W. A geomorphic perspective on nutrient retention following dam removal: Geomorphic models provide a means of predicting ecosystem responses to dam removal. BioScience 52, 693–701 (2002).

    Article  Google Scholar 

  185. 185.

    Merritts, D., Walter, R. & Rahnis, M. A. Sediment and nutrient loads from stream corridor erosion along breached millponds. Pennsylvania Department of Environmental Protection (2010).

  186. 186.

    Zhang, Q., Hirsch, R. M. & Ball, W. P. Long-term changes in sediment and nutrient delivery from Conowingo dam to Chesapeake Bay: effects of reservoir sedimentation. Environ. Sci. Technol. 50, 1877–1886 (2016).

    Article  Google Scholar 

  187. 187.

    Kiptala, J. K., Mul, M. L., Mohamed, Y. A. & van der Zaag, P. Multiobjective analysis of green-blue water uses in a highly utilized basin: case study of Pangani Basin, Africa. J. Water Resour. Plan. Manag. 144, 05018010 (2018).

    Article  Google Scholar 

  188. 188.

    Mul, M. et al. Trade-offs between ecosystem services and hydropower generation, case of the Akosombo and Kpond Dams, Ghana in International Conference on Water, Energy & Climate Change 39 (2016).

  189. 189.

    Kuby, M. J., Fagan, W. F., ReVelle, C. S. & Graf, W. L. A multiobjective optimization model for dam removal: an example trading off salmon passage with hydropower and water storage in the Willamette basin. Adv. Water Resour. 28, 845–855 (2005).

    Article  Google Scholar 

  190. 190.

    Jager, H. I., Efroymson, R. A., Opperman, J. J. & Kelly, M. R. Spatial design principles for sustainable hydropower development in river basins. Renew. Sustain. Energy Rev. 45, 808–816 (2015).

    Article  Google Scholar 

  191. 191.

    Hayes, D. S. et al. Advancing towards functional environmental flows for temperate floodplain rivers. Sci. Total Environ. 633, 1089–1104 (2018).

    Article  Google Scholar 

  192. 192.

    Yarnell, S. M. et al. Functional flows in modified riverscapes: hydrographs, habitats and opportunities. BioScience 65, 963–972 (2015).

    Article  Google Scholar 

  193. 193.

    Mannes, S. et al. Ecological effects of a long-term flood program in a flow-regulated river. J. Alpine Res. 96, 125–134 (2008).

    Google Scholar 

  194. 194.

    Bastviken, D., Tranvik, L. J., Downing, J. A., Crill, P. M. & Enrich-Prast, A. Freshwater methane emissions offset the continental carbon sink. Science 331, 50–50 (2011).

    Article  Google Scholar 

  195. 195.

    Li, S. et al. Large greenhouse gases emissions from China’s lakes and reservoirs. Water Res. 147, 13–24 (2018).

    Article  Google Scholar 

Download references


T.M. was funded through the Natural Sciences and Engineering Research Council of Canada (NSERC), award number PDF-516575-2018. Q.C. was funded through the National Natural Science Foundation of China (no. 91547206). L.B. was funded from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 765553, as part of the Euro-FLOW project.

Author information




All authors contributed to the researching of data and writing of the manuscript and to the discussion of the content. T.M., Q.C., L.B., K.V.M. and C.Z. reviewed and edited the manuscript before submission.

Corresponding authors

Correspondence to Taylor Maavara or Qiuwen Chen.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information

Nature Reviews Earth & Environment thanks Nathan Barros and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Related links

Public access to the GOOD 2 , GRanD and FHReD databases of existing and future dams and reservoirs worldwide, as well as links to external global and regional databases: http://globaldamwatch.org/



For nutrients, the net removal of nutrients or nutrient species from the water column in reservoirs via sedimentation and burial or gaseous evasion to the atmosphere.


The over-enrichment of a water body with nutrients, driving high primary production (photosynthesis) and excessive growth of algae, often resulting in harmful algal blooms or toxic cyanobacterial blooms and the development of anaerobic or anoxic conditions.


Biological reduction of nitrate (NO3) to N2 gas through a series of intermediate reaction steps that can produce nitrite (NO2), nitric oxide (NO) and nitrous oxide (N2O).

Redfield–Brzezinski ratio

An extension of the Redfield ratio (C:N:P = 106:16:1), the Redfield–Brzezinski ratio describes the average elemental molar composition of diatoms, defined as C:N:P:Si = 106:16:1:15–20.

Limiting nutrient

The nutrient that is stoichiometrically in short supply in a system, typically benchmarked in aqueous biogeochemistry using the Redfield or Redfield–Brzezinski ratios.


Primary production that derives carbon from carbon dioxide and energy from sunlight (photosynthesis) or an inorganic chemical.


The formation of methane by methanogenic microorganisms; a form of anaerobic respiration.


Describes a water body characterized by low nutrient concentrations and, thus, low primary productivity.


The biological oxidation of ammonium (NH4+) to nitrate (NO3). Produces nitrous oxide (N2O) as a by-product.

Biogeochemical reactivity

In first-order reaction kinetics, biogeochemical reactivity is represented by a rate constant (k) in units of inverse time (T−1) that is multiplied by the nutrient mass or concentration to calculate the rate or flux of a process.


Describes reactive, easily degradable, highly bioavailable chemicals.


A type of flow regulation that produces short-term, high-flow events in river discharge.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Maavara, T., Chen, Q., Van Meter, K. et al. River dam impacts on biogeochemical cycling. Nat Rev Earth Environ 1, 103–116 (2020). https://doi.org/10.1038/s43017-019-0019-0

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing