An introduction to river biodiversity, and how companies can meaningfully protect rivers throughout their operations and supply chains.
This edition of “The Just Transition Newsletter” by Palsa & Pulk was written by Krisna Baghouzian and Christine Nikander.
Why should companies protect river biodiversity?
Biodiversity is crucial to preserve a whole web of intricate interactions between species in ecosystems, which in turn ensure climate regulation,[i] food production, water purification and flood protection. With biodiversity loss, we can expect huge economic losses. This is best illustrated by the European Central Bank’s research from 2023, which shows that approximately 75% of all euro area corporate loans are strongly dependent on at least one ecosystem service.[ii]
While “covering less than 1% of the global surface area, freshwater ecosystems […] support a disproportionate number of flora and fauna”.[iii] Overall, wetlands host 40% of all species.[iv] As rivers connect different wetlands to one another, they are seen as “arteries of the landscape”.[v] In line with this, river ecosystems are also key hubs for biodiversity — with species living inside and outside of the water.
What threats are there to river biodiversity?
There are multiple threats that rivers and their vast biodiversity face. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) outlines five major drivers of biodiversity loss: “(1) changes in land and sea use; (2) direct exploitation of organisms; (3) climate change; (4) pollution and (5) invasive alien species”.[vi] Each of these drivers indirectly affect the reproductive abilities of species and directly affect factors in rivers such as water quantity (flow), quality, and how the river is connected from “source to sea”.[vii] This, in turn, affects ecological conditions in the river.
The listed drivers are exacerbated by climate change. A changing climate alters habitats through increased wildfires, extreme weather conditions, shifts in temperature and water distribution. A concrete example of climate change directly affecting river diversity is that it causes an increased irregularity of the flow of rivers and streams.[viii]
Why do barriers pose a threat to water habitats?
Change in water habitats can be seen in artificial barriers in waters, such as water-storing and hydroelectric dams. They hinder species migration in the river and alter water quality, sediment and nutrient flows. These are, notably, “environmental cues that are vital for species to complete their life cycles”.[ix] As hydropower dams are increasingly used to generate renewable electricity, it may be worth considering how “[i]mprovements to flow regulation, fishway design and sediment redistribution can mitigate these ecological impacts”. Moreover, “[f]uture research should support reforms to dam operations and design adaptations to balance renewable electricity development and biodiversity conservation through systematic basin-scale planning, long-term monitoring, adaptive management and involving multiple actors in decision-making”.[x]
Aside from aquatic species, terrestrial species also rely on rivers. River floodplains are highly concentrated with diverse habitats.[xi] For example, “gravel-bed river floodplains contain over half of [western North America’s] plant diversity”, while they cover less than 3% of the area.[xii] They are, therefore, vital to various species such as bears, birds, and microbes.[xiii] The floodplains are grounds for food and reproduction and also increase resilience to adapt to changing environments, exacerbated by climate change. Thus, the whole river channel — including floodplain and other connected waters, such as shorelines — support a diverse network of species. These are often threatened by structural modifications “such as roads, railways, and housing”,[xiv] or other engineering works such as the creation of waterways for shipping.[xv]
Unfortunately, “74% of [...] Europe’s floodplains show severe degradation”.[xvi] Due to “decades of river degradation”,[xvii] “only 40% of waterbodies presently achieve good ecological status and 17% of floodplain habitats achieve good conservation status”.[xviii] Overall, “[i]t is estimated that [global] habitat losses resulted in the decrease of 81% of monitored freshwater species populations between 1990 and 2012”.[xix] To combat the degradation of rivers, restoration work needs to account for the natural movement of the river. In this context, reintroducing “naturalized flooding regimes”[xx] and unfragmented “free-flowing rivers”[xxi] is advised.
How does increasing pollution impact rivers?
There are a variety of different industrial and other waste streams that find their way into rivers. Amongst these, particularly plastic pollution and pollution through perfluoroalkyl and polyfluoroalkyl substances (PFAS) are growing areas of concern.[xxii] Other polluters that harm aquatic life through direct discharge or runoff that flow into other bodies of water after rainfall include fertilizers, acids and toxic metals from mining, as well as medication from sewage.[xxiii]
Plastic waste harms organisms when it is ingested. Plastics — also when broken down into microplastics — disrupt the growth and reproductive ability of fish.[xxiv] Toxic waste, such as pesticides and insecticides from agricultural runoff, can furthermore interact with each other or other factors once released into the environment with unforeseen consequences. Going forward, it is therefore advised to monitor pesticides to account for unexpected risks once a chemical is released in the environment.[xxv] Environmental scientists warn that even pesticides marketed as more effective in lower doses — but that are higher in toxicity — are likely to cause higher ecological damage.[xxvi]
In line with this, the pollution of rivers, lakes, transitional and coastal waters through PFAS or so-called “forever chemicals” is increasing over time. There are around 10 000 different PFAS compounds, including the extremely persistent PFOS. The pollution of water through PFAS “can harm human health and the environment”.[xxvii] PFAS exposure also decreases the survival rate of (aquatic) species.[xxviii]
Overall, “only 29% of Europe’s waters achieved good chemical status over the 2015-2021 period”, according to a recent assessment from the European Environment Agency (EEA). A recent EEA study also “shows that most monitored rivers, transitional and coastal waters and a large part of lakes in Europe are polluted with at least one of the many extremely persistent chemical compounds that are deemed harmful for people and nature”. An analysis of data from 2022 showed that “59% of sites in rivers, 35% of sites in lakes, and 73% of sites in transitional and coastal waters [in Europe] exceeded the environmental quality standard for PFOS”.[xxix]
What does species exploitation do to river biodiversity?
The exploitation of species is another driver of biodiversity loss. For example, in Yellow River, China’s second longest river, overfishing has been identified as the main threat to fish diversity in the river basin.[xxx] To effectively protect biodiversity, the exploitation of species must firstly be managed. The Yellow River basin also shows how biodiversity loss often is a result of an interaction of multiple factors. Here, pollution from industrial activity has deteriorated water quality and the presence of non-native carp has led to the near extinction of the Yellow River carp.[xxxi]
Fishing in oceans can also affect species in rivers. A key example of this is the fishing of salmon as bycatch in the sea, before they can migrate back to their home rivers.[xxxii] It is, therefore, crucial to consider the (non-)intentional overexploitation of species across an entire hydrological system when addressing the decline of river biodiversity.
What can companies do to protect rivers?
Wetlands and riverine systems play a key role in protecting biodiversity, and they are therefore “central to any hopes of tackling the climate emergency facing our planet”.[xxxiii] Despite this, on “a global scale, 70% of rivers occur outside protected areas and only 11.1% are protected in their entirety”.[xxxiv] In practice, this means that steps need to be taken to ensure that bodies of water are (re)connected and that they are able to move freely. It also means that companies’ activities on land or connected bodies of water — such as the unintentional runoff of substances or how fishing in oceans affects species in rivers — must be considered and adequately managed.
Responsible companies aiming to contribute to positive change must take proactive steps to try and “reverse the decline of natural wetlands”.[xxxv] The Emergency Recovery Plan by Tickner et al. sets out “six priority actions to curb freshwater biodiversity loss”. The recommended actions are: “1) Accelerating implementation of environmental flows, 2) Improving water quality, 3) Protecting and restoring critical habitats, 4) Managing exploitation of freshwater species and riverine aggregates, 5) Preventing and controlling non-native species invasions, and 6) Safeguarding and restoring river connectivity”.[xxxvi]
In practice, this means that companies should ensure that water availability is managed, considering the connectivity of habitats, sediment flows, and natural movement of rivers. They should prevent chemicals from being released into the environment — or otherwise, carefully monitor these across entire hydrological systems. They should also closely monitor and manage the exploitation of species, as well as the broader effects this has on hydrological systems.[xxxvii]
The next newsletter will explore Indigenous Peoples’ rights to water. . If you want to be notified when it comes out, please subscribe to our mailing list.
About the authors
Krisna Baghouzian is a freelance sustainability consultant at Palsa & Pulk. She has a background in governance and past experience in working on sustainability at a local government with a people-centered approach. In her work, Krisna likes to take a holistic view of sustainability — by touching on different aspects of sustainability and their impact on our Earth and its inhabitants.
Christine Nikander is the founder of the environmental and social sustainability consultancy, Palsa & Pulk. She frequently speaks and writes about the environmental and human rights issues that arise through global supply chains and the energy transition. Christine studied law at the universities of Columbia (New York), Edinburgh (Scotland), and Leiden (the Netherlands). She has been writing The E-Waste Column weekly since 2022.
About Palsa & Pulk
Palsa & Pulk is an environmental and social sustainability consultancy. It provides compliance, governance, policy, and strategic advice to its clients. The consultancy’s work is mostly focused on supply chain governance, the just transition, circular economy, and human rights.
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[i] Rockstaröm et al., We need biosphere stewardship that protects carbon sinks and builds resilience (2021). https://www.pnas.org/doi/10.1073/pnas.2115218118 (20.02.2025)
[ii] European Central Bank (ECB), Occasional Paper Series No 333: Living in a world of disappearing nature: physical risk and the implications for financial stability (2023). https://www.ecb.europa.eu/pub/pdf/scpops/ecb.op333~1b97e436be.en.pdf (20.02.2025)
[iii] Anuradha Kumari and Sarika, “Riverine biodiversity and importance: Potential threat and conservational challenges”, Chapter 13 of Ecological Significance of River Ecosystems Challenges and Management Strategies (2022). https://www.sciencedirect.com/science/article/abs/pii/B9780323850452000091 (20.02.2025)
[iv] Wetlands International, Call for an ambitious Global Biodiversity Framework on World Wetlands Day 2020. https://www.wetlands.org/call-for-an-ambitious-global-biodiversity-framework-on-world-wetlands-day-2020/ (20.02.2025)
[v] Wetlands International, Rivers and Lakes. https://www.wetlands.org/our-work/rivers-and-lakes/ (20.02.2025)
[vi] Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), Media Release: Nature’s Dangerous Decline ‘Unprecedented’; Species Extinction Rates ‘Accelerating’. https://www.ipbes.net/news/Media-Release-Global-Assessment (20.02.2025)
[vii] Petersen et al., Incorporating free-flowing rivers into global biodiversity targets: Prioritization and targeted interventions to maintain ecological integrity (2022). https://onlinelibrary.wiley.com/doi/full/10.1002/aqc.3898 (20.02.2025); Harvey et al., How Hydrologic Connectivity Regulates Water Quality in River Corridors (2019). https://onlinelibrary.wiley.com/doi/10.1111/1752-1688.12691 (20.02.2025)
[viii] Gianuca et al., River flow intermittence influence biodiversity-stability relationships across spatial scales: Implications for an uncertain future (2024). https://pubmed.ncbi.nlm.nih.gov/39162046/ (20.02.2025)
[ix] Fengzhi He et al., Hydropower impacts on riverine biodiversity (2024). https://www.nature.com/articles/s43017-024-00596-0 (20.02.2025)
[x] Fengzhi He et al., Hydropower impacts on riverine biodiversity (2024). https://www.nature.com/articles/s43017-024-00596-0 (20.02.2025)
[xi] Fengzhi He et al., Hydropower impacts on riverine biodiversity (2024). https://www.nature.com/articles/s43017-024-00596-0 (20.02.2025)
[xii] Ric Hauer, Why river floodplains are key to preserving nature and biodiversity in the western US. https://theconversation.com/why-river-floodplains-are-key-to-preserving-nature-and-biodiversity-in-the-western-us-61839 (20.02.2025)
[xiii] Fengzhi He et al., Hydropower impacts on riverine biodiversity (2024). https://www.nature.com/articles/s43017-024-00596-0 (20.02.2025)
[xiv] Hauer et al., Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes (2016). https://www.science.org/doi/10.1126/sciadv.1600026 (20.02.2025)
[xv] Save Polesia, The route of E40 waterway. https://savepolesia.org/the-threat/faq/ (20.02.2025)
[xvi] Globevnik et al., ETC/ICM Report 5/2020: Preliminary assessment of river floodplain condition in Europe (2021). https://www.eionet.europa.eu/etcs/etc-icm/products/etc-icm-reports/preliminary-assessment-of-river-floodplain-condition-in-europe (20.02.2025)
[xvii] Perosa et al., A meta-analysis of the value of ecosystem services of floodplains for the Danube River Basin (2021). https://www.sciencedirect.com/science/article/abs/pii/S0048969721011293 (20.02.2025)
[xviii] European Environment Agency (EEA), Floodplains: a natural system to preserve and restore (2019). https://www.eea.europa.eu/en/analysis/publications/floodplains-a-natural-system-to-preserve-and-restore, p.5 (20.02.2025)
[xix] Petersen et al., Incorporating free-flowing rivers into global biodiversity targets: Prioritization and targeted interventions to maintain ecological integrity (2022). https://onlinelibrary.wiley.com/doi/full/10.1002/aqc.3898 (20.02.2025)
[xx] Ric Hauer, Why river floodplains are key to preserving nature and biodiversity in the western US. https://theconversation.com/why-river-floodplains-are-key-to-preserving-nature-and-biodiversity-in-the-western-us-61839 (20.02.2025)
[xxi] Petersen et al., Incorporating free-flowing rivers into global biodiversity targets: Prioritization and targeted interventions to maintain ecological integrity (2022). https://onlinelibrary.wiley.com/doi/full/10.1002/aqc.3898 (20.02.2025)
[xxii] European Environment Agency (EEA), ‘’Forever chemicals’ found above threshold levels in many water bodies in Europe. https://www.eea.europa.eu/en/newsroom/news/forever-chemicals-in-water-bodies (09.12.2024)
[xxiii] Agrani Paudel, Water Pollution: Sources, Pollutants, Types, Effects, Prevention. https://microbenotes.com/water-pollution/ (20.02.2025)
[xxiv] Wang et al., Meta-analysis of the effects of microplastic on fish: Insights into growth, survival, reproduction, oxidative stress, and gut microbiota diversity (2024). https://www.sciencedirect.com/science/article/abs/pii/S0043135424013927 (20.02.2025)
[xxv] Vijver et al., Postregistration Monitoring of Pesticides is Urgently Required to Protect Ecosystems (2017). https://scholarlypublications.universiteitleiden.nl/access/item%3A2939208/view (20.02.2025)
[xxvi] Tom Nederstigt and Martina G. Vijver, Nanotechnology promises to help farmers cut pesticide use – but could also make chemicals more toxic. https://theconversation.com/nanotechnology-promises-to-help-farmers-cut-pesticide-use-but-could-also-make-chemicals-more-toxic-223404 (20.02.2025)
[xxvii] European Environment Agency (EEA), ’Forever chemicals’ found above threshold levels in many water bodies in Europe (2024). https://www.eea.europa.eu/en/newsroom/news/forever-chemicals-in-water-bodies (20.02.2025)
[xxviii] Chambers et al., A review of per- and polyfluorinated alkyl substance impairment of reproduction (2021). https://www.frontiersin.org/journals/toxicology/articles/10.3389/ftox.2021.732436/full (22.11.2021)
[xxix] European Environment Agency (EEA), ’Forever chemicals’ found above threshold levels in many water bodies in Europe (2024). https://www.eea.europa.eu/en/newsroom/news/forever-chemicals-in-water-bodies (20.02.2025)
[xxx] Guo et al., Protect native fish in China’s Yellow River (2024). https://www.science.org/doi/10.1126/science.adn7432 (20.02.2025)
[xxxi] Guo et al., Protect native fish in China’s Yellow River (2024). https://www.science.org/doi/10.1126/science.adn7432 (20.02.2025)
[xxxii] Carla Roasch, Warming rivers and over-fishing leave native Alaskans facing 'salmon scarcity”. https://www.bbc.com/future/article/20240806-native-alaskans-facing-salmon-scarcity (20.02.2025)
[xxxiii] Wetlands International, Call for an ambitious Global Biodiversity Framework on World Wetlands Day 2020. https://www.wetlands.org/call-for-an-ambitious-global-biodiversity-framework-on-world-wetlands-day-2020/ (20.02.2025)
[xxxiv] Petersen et al., Incorporating free-flowing rivers into global biodiversity targets: Prioritization and targeted interventions to maintain ecological integrity (2022). https://onlinelibrary.wiley.com/doi/full/10.1002/aqc.3898 (20.02.2025); Abell et al., Looking Beyond the Fenceline: Assessing Protection Gaps for the World's Rivers (2017). https://conbio.onlinelibrary.wiley.com/doi/10.1111/conl.12312 (20.02.2025); Perry et al., Global Analysis of Durable Policies for Free-Flowing River Protections (2021). https://www.mdpi.com/2071-1050/13/4/2347 (20.02.2025)
[xxxv] Wetlands International, Call for an ambitious Global Biodiversity Framework on World Wetlands Day 2020. https://www.wetlands.org/call-for-an-ambitious-global-biodiversity-framework-on-world-wetlands-day-2020/ (20.02.2025)
[xxxvi] Tickner et al., Bending the Curve of Global Freshwater Biodiversity Loss: An Emergency Recovery Plan (2020). https://www.researchgate.net/publication/338344940_Bending_the_Curve_of_Global_Freshwater_Biodiversity_Loss_-_An_Emergency_Recovery_Plan (20. 02.2025)
[xxxvii] Tickner et al., Bending the Curve of Global Freshwater Biodiversity Loss: An Emergency Recovery Plan (2020). https://www.researchgate.net/publication/338344940_Bending_the_Curve_of_Global_Freshwater_Biodiversity_Loss_-_An_Emergency_Recovery_Plan (20. 02.2025); Gianuca et al., River flow intermittence influence biodiversity-stability relationships across spatial scales: Implications for an uncertain future (2024). https://pubmed.ncbi.nlm.nih.gov/39162046/ (20.02.2025)
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