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Despite their limited spatial extent, freshwater ecosystems host remarkable biodiversity, including one third of all vertebrate species. This biodiversity is declining dramatically: globally, wetlands are vanishing three times faster than forests, and freshwater vertebrate populations have fallen more than twice as steeply as terrestrial or marine populations. Threats to freshwater biodiversity are well documented but co-ordinated action to reverse the decline is lacking. We present an Emergency Recovery Plan to “bend the curve” of freshwater biodiversity loss. Priority actions include: 1) accelerating implementation of environmental flows; 2) improving water quality; 3) protecting and restoring critical habitats; 4) managing exploitation of freshwater ecosystem resources, especially species and riverine aggregates; 5) preventing and controlling non-native species invasions; and 6) safeguarding and restoring river connectivity. We recommend adjustments to targets and indicators for the Convention on Biological Diversity and the Sustainable Development Goals, and roles for national and international state and non-state actors. *** This paper has been accepted for publication in BioScience. A link to the BioScience version will follow in due course ***
Forum XXXX XXXX / Vol. XX No. X BioScience 1
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Bending the Curve of Global
Freshwater Biodiversity Loss:
An Emergency Recovery Plan
Despite their limited spatial extent, freshwater ecosystems host remarkable biodiversity, including one-third of all vertebrate species. This
biodiversity is declining dramatically: Globally, wetlands are vanishing three times faster than forests, and freshwater vertebrate populations have
fallen more than twice as steeply as terrestrial or marine populations. Threats to freshwater biodiversity are well documented but coordinated
action to reverse the decline is lacking. We present an Emergency Recovery Plan to bend the curve of freshwater biodiversity loss. Priority actions
include accelerating implementation of environmental flows; improving water quality; protecting and restoring critical habitats; managing the
exploitation of freshwater ecosystem resources, especially species and riverine aggregates; preventing and controlling nonnative species invasions;
and safeguarding and restoring river connectivity. We recommend adjustments to targets and indicators for the Convention on Biological
Diversity and the Sustainable Development Goals and roles for national and international state and nonstate actors.
Keywords: river restoration, wetlands, freshwater conservation, Sustainable Development Goals, Convention on Biological Diversity
Humans have caused widespread planetary change,
ushering in a new geological era, the Anthropocene
(a term first coined in the 1980s by Eugene F. Stoermer, a
freshwater biologist). Among many consequences, biodiver-
sity has declined to the extent that we are witnessing a sixth
mass extinction (Ceballos et al. 2017). Recent discourse
has emphasised the triple challenge of bending the curve
of biodiversity loss (Mace etal. 2018) while also reducing
climate change risks and improving lives for a growing
human population. In 2020, governments will review inter-
national agreements relevant to this challenge, including
the Convention on Biological Diversity (CBD) and the
Sustainable Development Goals (SDGs). There is a brief
window of opportunity now to set out recommendations
that can inform these agreements and guide future policy
Nowhere is the biodiversity crisis more acute than in
freshwater ecosystems. Rivers, lakes, and inland wetlands
(such as deltas, peatlands, swamps, fens, and springs) are
home to an extraordinary diversity of life. Covering less
than 1% of Earths surface, these habitats host approximately
one-third of vertebrate species and 10% of all species
(Strayer and Dudgeon 2010), including an estimated 70 spe-
cies of freshwater-adapted mammals, 5700 dragonflies, 250
turtles (Balian etal. 2008), 700 birds (IUCN 2019), 17,800
fishes (Fricke etal. 2019), and 1600 crabs (Neil Cumberlidge,
Northern Michigan University, 4th June 2019). The levels of
endemism among freshwater species are remarkably high.
For instance, of the fish species assessed for the freshwater
ecoregions of the world, over half were confined to a single
ecoregion (Abell etal. 2008).
Freshwater ecosystems also provide services to billions
of people, including impoverished and vulnerable com-
munities (Lynch etal. 2016). However, the management of
freshwater ecosystems worldwide has frequently prioritized
a narrow range of services for macroeconomic benefit at
the expense of habitats, flora and fauna, and the diverse
benefits they provide to communities. Consequently, the
current rate of wetland loss is three times that of forest loss
(Gardner and Finlayson 2018), and populations of freshwa-
ter vertebrate species have fallen at more than twice the rate
of land or ocean vertebrates (Grooten and Almond 2018).
2 BioScience XXXX XXXX / Vol. XX No. X
Of the 29,500 freshwater dependent species so far assessed
for the IUCN Red List, 27% are threatened with extinction.
Among these, an estimated 62% of turtle species, 47% of
gastropods, 42% of mammals, 33% of amphibians, 30%
of decapod crustaceans (crabs, crayfish, and shrimps),
28% of fishes, and 20% of birds are at risk (figure 1; IUCN
2019). Populations of freshwater megafauna, defined as
animals that reach a body mass of 30 kilograms, declined
by 88% from 1970 to 2012, with the highest declines in
the Indomalaya and Palearctic realms (−99% and −97%,
respectively; He etal. 2019).
The causes of these declines have been comprehen-
sively synthesised (e.g., Dudgeon etal. 2006, Reid et al.
2019), but no global framework exists to guide policy
responses commensurate with the scale and urgency of the
situation, and actions to safeguard freshwater biodiversity
have been “grossly inadequate” (Harrison et al. 2018).
Recommendations to address immediate threats to and
underlying drivers of global biodiversity loss have focused
mainly on terrestrial ecosystems, such as forests and grass-
lands (e.g., Kok etal. 2018) or have emphasised particu-
lar conservation strategies, such as enhancing protected
area coverage and condition (e.g., Dinerstein etal. 2019,
Visconti etal. 2019). Although they are valuable, these
proposals have either assumed, simplistically, that mea-
sures designed to improve land management will inevita-
bly benefit freshwater ecosystems, or they have neglected
to consider freshwater biodiversity at all. Anthropogenic
threats distinct to freshwater ecosystems, especially those
linked to hydrological regimes and loss of connectiv-
ity, have been insufficiently considered in international
conservation agreements and conventional conservation
strategies, impeding investment in appropriate policy and
management measures and contributing inadvertently to
the disproportionately high losses of
freshwater species and habitats.
In this article, we present an
Emergency Recovery Plan to reverse
the rapid worldwide decline in fresh-
water biodiversity. This plan extends
the concept of species recovery plans
established in legislation such as the
US Endangered Species Act 1973 and
the Australian Environment Protection
and Biodiversity Conservation Act
1999. Given the speed and extent of
collapse in freshwater biodiversity,
parallels can be drawn with postdisas-
ter recovery situations, and we have
deliberately used the word emergency
to convey the urgency with which con-
servationists, water managers, stake-
holders, and policymakers must act to
avoid further deterioration of habitats
and to promote recovery of biodiver-
sity. The plan is novel in this concep-
tual foundation, in its focus on solutions (rather than
documentation of threats) and in its explicit recommen-
dations for international agreements, especially the CBD
and the SDGs.
The Emergency Recovery Plan: Priorities for action
The plan is structured around six priority actions
(figure 2). Five of these focus on the major causes of
freshwater biodiversity loss described by Dudgeon and
colleagues (2006): flow alteration, pollution, habitat deg-
radation and loss, overexploitation of species, and inva-
sive nonnative species (INNs). In the priority action on
overexploitation we have considered exploitation of abi-
otic substrates, such as sand and gravel, alongside biota,
reflecting rising concerns about the damage to freshwater
ecosystems caused by rapid expansion of riverine aggre-
gate mining (UNEP 2019). We have also defined a sixth
priority action on connectivity because of the distinct
and pervasive role of dams and other infrastructure in
fragmenting freshwater ecosystems and disrupting move-
ments of water, species, sediments, and nutrients (Grill
etal. 2019). Just as threats to freshwater biodiversity loss
often act synergistically (Craig etal. 2017), so these prior-
ity actions should be considered and planned coherently
for maximum efficiency and impact. Measures to address
one cause of biodiversity loss can, in many contexts, help
address other causes too.
Given the scale of the crisis, the plan must be ambitious.
But it must also be technically feasible and pragmatic in
political and socioeconomic terms. As we outline in box 1,
each priority action has already been implemented success-
fully in one or more situations across the globe, providing
proof of concept and lessons that can inform how to scale
up efforts.
Figure 1. Proportions of freshwater taxa threatened with extinction. Source:
IUCN (2019).
Forum XXXX XXXX / Vol. XX No. X BioScience 3
Below, for each priority action, we briefly review the prob-
lem, potential policy and management solutions, and the
current implementation status of these solutions.
Action 1: Accelerate implementation of environmental flows. Water
management for power generation, for flood risk reduction,
or to store and deliver water for agricultural, industrial, or
domestic uses changes the quantity, timing, and variability
of water flows and levels. In doing so, it directly alters the
physical availability of freshwater habitats, their ambient
conditions, connectivity between habitats, and ecosystem
processes such as sediment flow. These alterations, in turn,
affect functional links between hydrological regimes and the
life histories of freshwater species (Bunn and Arthington
2002) and therefore contribute substantially to losses of
freshwater biodiversity. Climate change exacerbates flow
alteration in many situations (Döll and Bunn 2014).
Maintaining or restoring ecologically important attributes
of hydrological regimes improves biodiversity outcomes
(Poff etal. 1997, Bunn and Arthington 2002, Olden etal.
2014). The science and practice of environmental flow
assessment enables identification and quantification of these
attributes. A sophisticated methodological toolbox now
exists for developing environmental flow scenarios and rec-
ommendations in a wide range of water resource manage-
ment contexts, from minimally altered to heavily managed
freshwater ecosystems (Acreman etal. 2014, Poff etal. 2017).
Many environmental flow assessment tools consider desired
socioeconomic and cultural objectives alongside biodiver-
sity goals, aiding incorporation of recommendations into
river basin plans, water allocation regimes, and design
and operation of water infrastructure. The 2018 Brisbane
Declaration and Global Action Agenda on Environmental
Flows set out 35 recommendations to accelerate implemen-
tation (Arthington etal. 2018).
Environmental flows have been incorporated into poli-
cies in many jurisdictions (Le Quesne et al. 2010). As
long ago as 1968, the United States passed the Wild and
Scenic Rivers Act (1968), which mandates the conservation
of rivers of oustanding natural, cultural and recreational
value, including through maintenance of their free-flowing
character. More recently, the European Union has recom-
mended the inclusion of environmental flows in river basin
management plans required by the EU Water Framework
Directive (European Commission 2015), the nine Nile
Basin countries have agreed a common environmental flow
assessment strategy (NBI 2016), and China has integrated
environmental flows into environmental impact assessment
laws (Chen and Wu 2019). Examples of environmental flow
implementation have been documented from diverse con-
texts (Harwood etal. 2017), but these are currently isolated
successes. Human demands for water will increase in some
Figure 2. The Emergency Recovery Plan for freshwater biodiversity: Six priority actions for global action to bend the curve
of freshwater biodiversity loss that should be reflected in the post-2020 biodiversity framework. Threats to freshwater
biodiversity are often synergistic so coherent planning of interacting priority actions to address such threats is necessary.
4 BioScience XXXX XXXX / Vol. XX No. X
Box 1. Examples of implementation of priority actions in the emergency recovery plan for Freshwater Biodiversity.
Box 1. Examples of implementation of priority actions in the Emergency Recovery Plan for Freshwater Biodiversity.
Accelerate implementation of environmental ows
River basin planning. Environmental flows have been incorporated into water legislation in South Africa and implemented through legally
mandated catchment management agencies—for example, on the Crocodile River.
Water allocation. Mexico’s Water Reserves initiative sets sustainable water allocation limits for 189 rivers across the country, taking account
of environmental flows.
Infrastructure design and operation. Environmental flows to benefit downstream fisheries are now part of the operational regime of the
Three Gorges Dam, China.
Improve water quality to sustain aquatic life
Waste water treatment. The EU Urban Waste Water Treatment Directive has led to widespread reduction in sewage pollution.
Regulation of polluting industries. In Singapore, a large-scale project was launched in the 1970s to clean up the Singapore River and restore
aquatic life, including through removal and relocation of pollution from pig and duck farms and from industry while encouraging business
and residential development along the waterfront.
Market instruments. Around Lake Taupo, New Zealand, catchment scale nitrogen caps combined with farm-based permits and trading and
establishment of a trust fund to help reduce costs of nitrogen-reducing practices for farmers, has helped to tackle persistent diffuse pollution
problems linked to pastoral agriculture.
Improved agricultural practices. Better management practices on cotton and sugarcane farms in India and Pakistan, encouraged by market-
based initiatives such as the Better Cotton Initiative and Bonsucro, have led to reductions in pesticides and fertilizers reaching watercourses.
Nature-based solutions. In China, restoration efforts for floodplain lakes along the central Yangtze River have resulted in improvements in
lake water quality with consequent enhancement of fisheries and floodplain biodiversity.
Protect and restore critical habitats
Protected areas. Among many examples of successful protected area designation and management, the gazettement by the government of
Colombia of the entire 825,000 hectares Bita River basin (a subbasin of the Orinoco) as a Ramsar site is a rare example of a free-flowing river
and its entire basin being protected through an international designation.
Land-use planning or markets for ecosystem services. The New York City Watershed Agreement has stimulated improved land use planning
and management to protect and restore ecosystem processes in the Castkills–Delaware watersheds, safeguarding urban water supplies in a
cost-effective way in the process.
Habitat restoration. Approximately 60,000 hectares of floodplain wetlands have been restored along the lower Danube River as a result of an
international agreement signed by ministers from Bulgaria, Romania, Moldova, and Ukraine.
Manage exploitation of freshwater species and riverine aggregates
Science-based fisheries management. In Malawi, the Ecosystem Approach to Fisheries management has been enshrined in legislation since
the 1990s, with implementation efforts incorporating comanagement with fishery communities, a focus on sustainable harvest of high value
Chambo (Oreochromis lidole) and breeding or nursery sanctuaries for commercial species.
Community fisheries management. A community protection and resource management program within oxbow lakes on the Juruá River
within the Western Brazilian Amazon resulted in a thirtyfold increase in Arapaima, Arapaima gigas.
Bycatch reduction. A combination of closures and modified traps have been demonstrated to minimize platypus bycatch within commercial
eel and carp fisheries in New South Wales, Australia.
Reducing aggregates demand. Germany recycles 87% of its waste aggregates, and in India nontoxic municipal waste is used as an aggregates
substitute in road building.
Improved regulation of riverine aggregate extraction. In the United Kingdom, an effective regulatory regime to determine the acceptability
(or otherwise) of riverine aggregate extraction has been complemented by the aggregates levy, a tax placed on sales of primary aggregates in the
United Kingdom (sand, gravels and crushed rock), which has funded research to develop understanding and improve practices to minimize
environmental effects of extraction.
Prevent and control nonnative species invasions in freshwater habitats
Identification and control of introduction pathways. Prevention of nonnative carp species invasions in the Great Lakes (United States and Canada)
has successfully used a combination of scientific risk assessments, prohibition of live fish transport, and an electrical barrier.
Control and eradication of established invasive nonnative species. The spread of invasive nonnative weeds such as Mimosa pigra was limited
because of management measures implemented within the Kakadu National Park, Australia, at a cost of AUS$500,000 per year. Management
measures were found to avoid an increase in Mimosa pigra coverage compared with areas that were not managed.
Safeguard and restore freshwater connectivity
System-scale infrastructure planning. A strategic environmental assessment for hydropower planning has been undertaken in Myanmar that
has recommended keeping the main stems of the Irrawaddy and Salween rivers free flowing.
Dam reoperation and removal. On the Penobscot River, in the United States, reoperation and removal of dams affecting 1500 kilometers of
river resulted in increased populations of migratory fish species while maintaining electricity generation capacity.
Levee repositioning. The Room for the Rivers program in the Netherlands has stimulated large-scale levee removal and restoration of lateral con-
nectivity along the Rhine to enhance flood storage and conveyance while also providing expanded and enhanced habitat for freshwater biodiversity.
Forum XXXX XXXX / Vol. XX No. X BioScience 5
regions, making implementation more challenging (Palazzo
et al. 2019). The transboundary characteristics of many
freshwater ecosystems further complicate implementation
(Brown and King 2013). Even so, improved water alloca-
tion planning (Speed et al. 2013) and wiser agricultural
water use (Linstead 2018) can create opportunities for prog-
ress. Shifting agricultural production to less water-stressed
regions could also help (Pastor etal. 2019).
Action 2. Improve water quality to sustain aquatic life. Pollution
impacts on freshwater biodiversity can be profound and can
reflect direct toxicity or disruption to ecosystem processes.
Pollution types include but are not limited to nutrients from
sewage, fertilizers, or animal wastes; synthetic chemicals,
such as pesticides, herbicides, heavy metals, persistent
organic pollutants, and a wide range of other hazardous
substances from agriculture and industry; pharmaceuticals
and their metabolites from human and agricultural use;
plastics across a wide size spectrum; sediments mobilized
by agriculture, forestry, and mining operations; salinization
caused by sea water incursion or overirrigation; and heat
from industrial and power sector effluents (Reid etal. 2019).
Policy and management options include improved waste-
water treatment or reuse, regulation of polluting industries,
market instruments that reflect downstream pollution costs,
improved agricultural practices, and nature-based solutions
such as floodplain wetland restoration or riparian buffer
zones (WWAP 2017).
Globally, 80% of sewage enters surface waters without
adequate treatment and in Latin America, Africa, and Asia,
approximately 15% of river lengths are severely polluted
organically (UNEP 2016, WWAP 2017). Improved waste-
water treatment should therefore be a priority for many
countries. The Clean Water Act (1972) in the United States,
and the European Union’s Urban Wastewater Treatment
Directive (1991) have helped to slow and, in some cases,
reverse point–source pollution in those jurisdictions
(Vaughan and Ormerod 2012). Nonpoint–source pollution
from agriculture remains a problem across many regions
(OECD 2017). Better farm management, often in com-
bination with market mechanisms, can reduce pollution
loads while maintaining agricultural yields (Wu and Ma
2015) but is not yet mainstream agricultural practice. In
the European Union, for instance, agricultural pollution is
a major reason for failure to attain “good ecological status”
as required by the Water Framework Directive (European
Environment Agency 2018). Improved water quality moni-
toring is required in many contexts, using existing guidelines
(e.g., UN Environment 2017). Evidence is urgently needed
on the sources, pathways, and impacts of some pollutants,
including microplastics and pharmaceuticals, to inform
policy and management (Reid etal. 2019).
Action 3. Protect and restore critical habitats. An estimated 30%
of natural freshwater ecosystems have disappeared since
1970, and 87% of inland wetlands since 1700 (Davidson
2014, Dixon etal. 2016). Causes include land conversion to
agriculture and reduced hydrological connectivity after dam
and levee construction (Junk etal. 2013; the impacts of dams
and levees on freshwater ecosystem connectivity is discussed
in priority action 6 below). Climate change can alter wetland
distribution and extent (Acreman etal. 2019) and affect the
frequency and intensity of flood events, which then affects
fluvial geomorphological processes and habitat structure
(Death etal. 2015). Changes in terrestrial habitat manage-
ment caused by forestry, intensive agriculture, mining, road
construction, and urbanization have exacerbated pollution,
sediment fluxes, and extreme flows, affecting freshwater
habitats downstream (Dudgeon etal. 2006).
A variety of interventions can mitigate the impacts on
freshwater biodiversity from prior degradation and reduce
future risks. These include community conservation of
habitats for flagship, keystone, or culturally important spe-
cies; formal protected area designations; land-use planning
(often linked with markets for ecosystem services); and
habitat restoration programs (UN Water 2018). Strategic
basin-scale planning of conservation and restoration invest-
ments can help to identify synergies and resolve trade-offs
between biodiversity goals and other priorities. In doing so,
it can increase social and political support for conservation
and restoration and ensure that freshwater biodiversity and
ecosystem services outcomes are more effective and resilient
to future conditions (Speed etal. 2016). Systematic freshwa-
ter conservation planning tools, which combine stakeholder
engagement with algorithm-based spatial assessment taking
specific account of hydrological factors, can aid prioritiza-
tion of freshwater habitats for efficient conservation and
restoration investments (Reis etal. 2019).
Many freshwater ecosystems are ostensibly protected by
international or national designations. For instance, the
Ramsar Convention on wetlands now has 168 contracting
parties worldwide who have designated 2186 Ramsar sites,
covering 2.1 million square kilometers. However, formal
protection has been inconsistently effective, and there is
scope for wider application of lessons from successful
protection efforts, such as the involvement of local com-
munities in protected area management (Acreman et al.
2019). A lack of effective basin-scale planning and failure to
address exogenous threats have also limited the biodiversity
benefits of protection (Reis etal. 2017). The management
of terrestrial-focused protected areas often fails to consider
associated freshwater ecosystems and sometimes permits
activities detrimental to their health, such as the building
of dams. Protected area designations that are specifically
focused on limiting threats distinct to freshwater ecosys-
tems are relatively uncommon globally, but the US Wild
and Scenic Rivers Act, Norway’s National Salmon Rivers
designations, and Mexico’s Water Reserve policy have been
used to maintain free-flowing rivers. The implementation
of similar policies will be important for protecting healthy
rivers in regions undergoing expansion of infrastructure
construction (Moir etal. 2016).
6 BioScience XXXX XXXX / Vol. XX No. X
River basin planning is enshrined widely in policies,
including in places such as China, the European Union, and
Brazil. Some countries, such as Uganda, have developed spe-
cific national wetland policies. Others, such as South Africa,
have incorporated wetland conservation into agriculture,
water, or other sectoral policies. While recognizing that
nature-based solutions to water management challenges are
not a panacea, the UN has recommended greater investment
in them as potentially cost-effective substitutes for or aug-
mentations to conventional built infrastructure (UN Water
2018). The UN Framework Convention on Climate Change
(UNFCCC) also encourages consideration of nature-based
solutions within Nationally Determined Contributions, and
there is scope for these solutions to provide cobenefits in
terms of climate mitigation, freshwater biodiversity recov-
ery, and socioeconomic resilience. Nevertheless, large-scale
implementation of nature-based solutions is in its infancy.
Action 4. Manage exploitation of freshwater species and riverine
aggregates. The exploitation of living organisms and mineral
substrates affects freshwater biodiversity directly through
removal of individuals and their habitats and indirectly
through alterations to freshwater ecosystem processes. A wide
range of freshwater taxa are exploited, including plants, inver-
tebrates (such as crabs and crayfish), fish, amphibians (such
as frogs), reptiles (including turtles and their eggs), water-
birds (including geese and ducks), and mammals (including
river dolphins and otters). Policy frameworks to guide such
harvests are often insufficient, and enforcement is also poor,
making sustainable management difficult (Cooke etal. 2016).
Bycatch is a further threat, such as of river dolphins that are
accidentally caught in gill nets (Iriarte and Marmontel 2013).
The extraction of riverine substrates, especially sand and
gravel for use in construction, is increasing rapidly (UNEP
2019). Research into biodiversity impacts is sparse, but its
effects can include direct destruction of instream and riparian
flora and fauna, as well as changes to fluvial geomorphologi-
cal regimes with associated effects on downstream habitats
(Koehnken and Rintoul 2018). (The abstraction of water
resources from freshwater habitats is discussed above in rela-
tion to action 1, on implementing environmental flows.)
The 2016 Rome Declaration, convened by the Food and
Agriculture Organization of the United Nations, describes
the steps needed for sustainable freshwater fisheries,
including improved biological assessments, science-based
management, and the development of a global freshwater
fisheries action plan (Taylor and Bartley 2016). Bycatch can
be reduced by exploiting temporal and spatial differences
between target species and bycatch distributions. Mandatory
bycatch reporting can also help (Cairns etal. 2013), as can
technology, such as provision of air spaces to increase sur-
vival rates of animals accidentally caught in nets (Grant etal.
2004). Solutions to riverine sand and gravel extraction can
include reducing demand for construction materials (such as
through avoiding overdesign in buildings) and substituting
recycled materials for new concrete, supported by improved
supply chain standards (UNEP 2019). Sustainable manage-
ment of aggregate extraction rates, locations, and methods
can be informed by analysis of geomorphological processes,
and extraction can be focused on river reaches where natural
accumulations of sand and gravel can accommodate removal
without harming ecosystem structure and function.
Currently, lack of data and science-based management
is a major concern for both freshwater fisheries (Bartley
etal. 2015) and riverine aggregate extraction (UNEP 2019).
The implementation of robust legal frameworks is also
rare. However, there have been promising developments
in fisheries policy since the Rome Declaration. These
include improved planning processes in some countries
(such as Cambodia) and the development of international
standards for biological assessment (Bonar et al. 2017).
Successful community-based fisheries management, lead-
ing to biodiversity benefits, has been documented from
Thailand (Koning 2018) and Brazil (Campos-Silva and Peres
2016). Riverine aggregate extraction has been brought under
improved regulatory control across parts of Europe but else-
where, and especially in Asia, it is rapidly expanding and is
often unregulated or illegal (Koehnken and Rintoul 2018).
Action 5. Prevent and control nonnative species invasions in fresh-
water habitats. Freshwater habitats are especially susceptible
to INNS (Strayer 2010). The impacts of INNS on freshwater
biodiversity range from behavioral shifts of native spe-
cies to complete restructuring of food webs and extirpa-
tion of entire faunas (Gallardo etal. 2016). The economic
costs are also significant, reaching billions of dollars in the
United States alone (Pimentel etal. 2005). However, because
of insufficient information, public awareness, and policy
frameworks, the effects of INNS are consistently underesti-
mated (Early etal. 2016).
Preventing introduction of INNS is the best approach
to limiting impacts. Efforts have been focused on identi-
fying major introduction pathways, such as trade in live
organisms, ballast-water transfers from ships, releases of
unwanted animals from aquariums, and aquaculture and
horticulture escapes. Once they are established, control and
eradication of INNS is normally possible only with consid-
erable investments in physical removal, chemical treatment,
or biological control. Climate change and globalization
increase the risk that species currently inhabiting a limited
geographic range or nonnative species that have to date
only had moderate ecological or economic impacts might
become more problematic. New strategies will be needed
to prevent invasion and control the impacts of such species
(Rahel and Olden 2008).
In a few instances, countries have taken steps to identify
and prioritize INNS for action. In the United States, inva-
sive species advisory councils bring together regulators,
researchers, and stakeholders to address research, policy,
and management needs related to INNS (Lodge etal. 2006).
For example, efforts are continuing to prevent nonnative
carp species from invading the Laurentian Great Lakes using
Forum XXXX XXXX / Vol. XX No. X BioScience 7
scientific risk assessments, laws prohibiting transportation
of live fish, and an innovative electrical barrier. Public or
commercial hunts and harvests have been encouraged to
eradicate established INNS from freshwater ecosystems,
such as in the removal of nutria (Myocastor coypus) from the
United Kingdom (Pasko etal. 2014). Although policies and
strategies often target specific INNS (Early etal. 2016), the
European Union recently adopted a regulation (2016/1141),
which requires member states to prevent, control, or eradi-
cate a suite of INNS, including several freshwater plant and
animal species.
Action 6. Safeguard and restore freshwater connectivity. The flows
of water, nutrients, and sediment through freshwater eco-
systems are important processes regulating biodiversity.
Many species depend on periodic connectivity between
upstream and downstream river reaches or between river
channels and floodplain habitats for their migration and
reproduction (McIntyre etal. 2016). Dams and weirs frag-
ment longitudinal (upstream to downstream) connectivity
and, through flow alterations, also affect lateral (river to
floodplain), vertical (surface to groundwater), and temporal
(season to season) connectivity. Engineered levees and other
flood management structures separate rivers from their
floodplains. Grill and colleagues (2019) measured connec-
tivity in river systems globally and found that only one-third
of the world’s very long rivers remain free flowing. Higher-
resolution local data reveals that, in some regions, fragmen-
tation rates are considerably higher (e.g., Jones etal. 2019).
Coherent planning for energy and water, including stra-
tegic siting of new infrastructure, can balance connectivity
maintenance with hydropower generation or water storage
(Opperman et al. 2019a). This can be achieved through
system- or basin-scale planning and strategic environ-
mental assessment processes that consider how potential
infrastructure portfolios deliver against multiple river man-
agement objectives. Individual dams can be designed and
operated to improve passage of sediment, nutrients, and
biota, although, to date, such interventions have had limited
efficacy (Noonan etal. 2012). Targeted removal of obsolete
dams can restore longitudinal connectivity in degraded
ecosystems. Removal or repositioning of levees can improve
lateral connectivity while enhancing water storage or con-
veyance on floodplains as part of flood risk management
strategies (Sayers etal. 2014).
Dams and levees continue to be built worldwide, often in
the absence of adequate planning processes. One study iden-
tified approximately 3700 new hydropower dams worldwide
at varying stages of the planning process (Zarfl etal. 2015).
Climate impacts (such as increased flood frequency or
intensity) can lead to increased pressure to build infrastruc-
ture in river basins, including dams and levees. Case studies
of improved system-scale water infrastructure planning are
emerging though. In Myanmar, a strategic environmental
assessment identified tributaries where new hydropower
dams would incur lower environmental and social risks
compared to other siting options and recommended keep-
ing the main stem Irrawaddy and Salween rivers free flow-
ing to maintain migratory fish populations and sediment
delivery to deltas (ICEM 2018). Some river- specific protec-
tion mechanisms described under priority action 3, such
as the United States’ Wild and Scenic Rivers Act, contain
provisions to safeguard connectivity. On the Penobscot
River, in the United States, a system-scale approach led
to the removal of two dams and refurbishment of others,
resulting in increased populations of migratory fish species
(Hogg etal. 2015). Dam removal has gathered pace in recent
years with more than 1600 barriers removed in the United
States alone (American Rivers 2019). On rivers such as the
Mississippi, the Rhine, and the Yangtze, floodplains have
been reconnected with rivers through levee repositioning
and reoperation of sluice gates as part of flood management
system upgrades (Opperman etal. 2017, Sayers etal. 2014).
Using the Emergency Recovery Plan to set global
targets and indicators for freshwater biodiversity
If these priority actions are to be progressed widely and
rapidly, a coordinated international effort will be needed
to transform underlying socioeconomic drivers of fresh-
water biodiversity declines, stemming from food, energy,
industrial and infrastructure sectors, and economic plan-
ning paradigms and to promote protection and recovery
of freshwater biodiversity through improved and better
integrated conservation practice and water resource man-
agement. International agreements can facilitate this coor-
dination, galvanize national policy development, and guide
investments by state and nonstate actors. As governments
and other stakeholders consider a post-2020 framework
for biodiversity and sustainable development, what targets
and indicators can be embedded within international agree-
ments to help bend the curve of freshwater biodiversity loss?
We have prioritised 13 existing or potential targets and
indicators within the CBD and SDGs that would substan-
tially advance implementation of the Emergency Recovery
Plan (table 1a, b). The recommendations focus on CBD
and the SDGs as these international agreements are due to
be reviewed or revised in 2020. Other agreements will also
have an important role to play, including those that specifi-
cally address freshwater conservation challenges, such as the
Ramsar Convention and those primarily focused on other
issues such as the UNFCCC, implementation of which
could accelerate nature-based climate solutions that might
also promote freshwater biodiversity recovery. Improved
coordination and mutual reinforcement between all such
agreements will be necessary (Bunn 2016). Involving fresh-
water ecosystem and biodiversity experts in discussions on
targets and indicators for these global agreements will also
be essential.
Several of our recommendations suggest maintaining
existing elements of these agreements that are already
aligned to the plan. For instance, although it does not spe-
cifically mention freshwater biodiversity, CBD Aichi target
8 BioScience XXXX XXXX / Vol. XX No. X
Table 1a. Advancing the Emergency Recovery Plan for freshwater biodiversity through international agreements:
Recommendations for global targets and indicators to be incorporated into the Convention on Biological Diversity.
Existing target Recommendation, including whether to maintain, amend
or devise new targets or indicators
Alignment with Emergency Recovery Plan
CBD Aichi target 5:
Habitat loss
Amend: Explicitly emphasize freshwater ecosystems, alongside
forests; use connectivity status index (Grill etal. 2019) and an
indicator of wetland extent for indicators.
Priority action 3: Protect and restore critical habitats
Priority action 6: Safeguard and restore freshwater
CBD Aichi target 6:
Fisheries management
Amend and new: Explicitly reference inland fisheries; add new
indicators and align with SDG 14.4 (see recommendations
Priority action 4: Manage exploitation of species
and riverine aggregates
CBD Aichi target 8:
Pollution reduction
Amend: Expand text and indicators to explicitly focus on the
full range of pollution, including emerging contaminants such
as pharmaceuticals and plastics, to emphasise addressing
pollution at source rather than through end-of-pipe fixes, and
to emphasise the need to retrofit waste water treatment where
necessary; include freshwater eutrophication alongside coastal
eutrophication in indicators.
Priority action 2: Improve water quality
CBD target 9: Invasive
Maintain and amend: Existing target is aligned with Emergency
Recovery Plan; amend wording and indicators to reflect the
vulnerability and sensitivity of freshwater ecosystems to
Priority action 5: Control invasive species
CBD target 11:
Protected areas
Amend and new: Define a distinct subtarget for proportion of
inland waters under protection by 2030. Add new indicator of
length (in kilometers) of riverine habitat that is protected and
connected, including riparian habitats, headwater streams, etc.
Use Connectivity Status Index (Grill etal. 2019) as an indicator
to track connectivity for freshwater species.
Priority action 3: Protect and restore critical habitats
Priority action 6: Safeguard and restore freshwater
CBD target 14:
Ecosystem services
Amend: Revise wording to emphasize the full range of services
that freshwater ecosystems provide, rather than only mentioning
water supply, and to emphasize the need to balance ecosystem
service provision with maintenance or restoration of ecosystem
structure and processes.
Priority action 1: Accelerate implementation of
environmental flows
Priority action 3: Protect and restore critical habitats
Priority action 4: Manage exploitation of species
and riverine aggregates
Priority action 6: Safeguard and restore freshwater
No current target New: Define new targets, relevant to CBD strategic goal B
(Reduce direct pressures on biodiversity), for maintaining
natural flows and restoring environmental flows, and managing
extraction of riverine aggregates; align these targets with,
respectively, SDG 6.4 and SDG 9.4 (see below).
Priority action 1: Accelerate implementation of
environmental flows
Note: For simplicity and ease of reference, we have followed the existing architecture of CBD Aichi targets. If governments agree to restructure
these targets and indicators in 2020, it will be important that the recommendations in the present article are integrated appropriately into the
new architecture.
9 on invasive species is well aligned to priority action 5.
Similarly, SDG 6 (“Clean water and sanitation”) already sets
out a target for improving water quality (SDG 6.3) that links
directly with priority action 2. In principle, SDG 6.4, on
sustainable water withdrawals, is aligned with priority action
1 from the plan on implementing environmental flows,
although there is scope within this target to improve assess-
ment of environmental flow implementation and to encour-
age use of an explicit indicator of progress (FAO 2019).
A second category includes recommendations for amend-
ing or extending existing targets or indicators such that they
align more strongly with the plan. For example, CBD Aichi
target 11 and SDG 15.1 both aim to increase the extent of
habitats that are conserved, restored or sustainably managed,
and both specifically reference “inland waters.” However,
these targets, and their associated indicators, are currently
described in terms of the area of ecosystems to be protected.
Much freshwater biodiversity is found in linear river systems
and associated headwater, riparian, and floodplain habitats.
A global target and associated indicator for freshwater bio-
diversity conservation and restoration would therefore be
better framed in terms of length of riverine (and associated
riparian and wetland) habitat protected and sustainably
managed. This target should also acknowledge the need
to protect or sustainably manage a wide range of different
freshwater habitat types including—for instance, headwa-
ter streams, ponds, and other small wetland habitats that
are important for biodiversity (Biggs etal. 2017). Another
example of an existing target that should be extended is SDG
6.6 (protecting and restoring water-related ecosystems),
which is due to expire in 2020. Extending this target to 2030
will increase coherence with other targets and encourage
continued action.
A third group of recommendations concerns the need for
new targets or indicators to fill major gaps. Currently, there is
no recognition of alterations in water flows and levels within
the CBD Aichi targets. This is a significant shortcoming,
so a new target on safeguarding natural flow regimes and
implementing environmental flows is needed. Extraction of
riverine sand and gravel is another notable omission from
both CBD and SDG targets and indicators. We recommend
inclusion within SDG 9.4 (sustainable infrastructure) of an
Forum XXXX XXXX / Vol. XX No. X BioScience 9
indicator on the proportion of construction materials that
are made from sustainably sourced aggregates and cross-
referencing to a new CBD target. This target should also
include explicit reference to the role of nature-based solu-
tions as potential alternatives to engineered infrastructure.
Freshwater fisheries too are poorly served by current targets
and indicators. SDG 14 includes targets for regulation of
overfishing (SDG 14.4), but this goal only covers marine
fisheries even though wild caught freshwater fish provide
critical protein for hundreds of millions of people (Funge-
Smith 2018). Therefore, we recommend addition of a spe-
cific indicator on freshwater fisheries and reframing of this
target to cover all aquatic habitats.
From international agreements to implementation:
Roles for national and international actors and the
research community
Bending the curve for freshwater biodiversity ultimately
hinges on the extent to which effective policy and manage-
ment interventions, as illustrated in box 1, can be repli-
cated or adapted worldwide. International agreements can
stimulate such replication, as we have discussed. However,
national and local state and nonstate actors must play
the central roles in defining context-specific portfolios
of measures that address synergistic threats to freshwater
biodiversity. Transparent decision-making, coherent target
setting and planning processes, and the use of appropriate
regulatory and financial mechanisms will all be necessary to
underpin development and implementation of measures. A
systemic approach to stakeholder engagement and dialogue
will be needed, involving multiple stakeholders and a broad
range of skills and disciplines to ensure a coherent approach
to policy and planning for freshwater ecosystem manage-
ment (Tickner et al. 2017). Active involvement of and
leadership by those most affected by management of fresh-
water habitats and biodiversity will be essential, including
local communities, women, young people, and indigenous
groups. The presence of “policy entrepreneurs” (Huitema
etal. 2011) or “champions” (O’Keeffe 2018), who recognize
opportunities for restoration and galvanize coordinated
action, can accelerate progress. Depending on the context,
these roles can be played by politicians, business leaders,
community representatives, nongovernmental organization
(NGO) experts, media personalities, or schoolchildren. To
nurture future champions, educators will need to reflect
the challenges facing freshwater (and other) biodiversity in
school curricula, and universities should incorporate train-
ing on strategy, communications, and stakeholder engage-
ment into technical degree programs on conservation, water
resource management, and related disciplines.
The mitigation hierarchy—which is focused sequentially
on avoiding, minimizing, restoring, and, finally, offset-
ting impacts of economic development on ecosystems and
biodiversity—might be a useful tool as these actors develop
context-specific portfolios of measures (Arlidge etal. 2018).
In many contexts, a high priority for freshwater biodiversity
conservation should be the avoidance of in situ or exog-
enous threats, such as dams, that would adversely affect
Table 1b. Advancing the Emergency Recovery Plan for freshwater biodiversity through international agreements:
Recommendations for global targets and indicators to be incorporated into the Sustainable Development Goals.
SDG 6.3: Water quality Maintain: Existing target and indicators are aligned with
Emergency Recovery Plan, as long as the definition of “ambient
water quality” in indicator 6.3.2 incorporates the full range of
pollution, and its sources, affecting freshwater ecosystems.
Priority action 2: Improve water quality
SDG 6.4: Sustainable
water withdrawals
Maintain and new: Existing target is aligned with Emergency
Recovery Plan. A new indicator is needed on the proportion of
water bodies with environmental flows implemented.
Priority action 1: Accelerate implementation of
environmental flows
SDG 6.6: Water-related
Amend: Extend target timeline to 2030 to encourage continued
effort; improve indicator 6.6.1 so that it tracks the extent of
only natural inland water ecosystems, i.e., excluding artificial
water bodies such as reservoirs; strengthen links with SDG 15
by explicit cross-reference to indicator 15.1.2 (proportion of
important sites for terrestrial and freshwater biodiversity that
are covered by protected areas).
Priority action 3: Protect and restore critical habitats
SDG 9.4: Sustainable
Amend and new: Incorporate an emphasis on green
infrastructure or nature-based solutions alongside engineered
infrastructure. Include new indicator of sustainability of sand
and gravel sources used in concrete for construction
Priority action 3: Protect and restore critical habitats
Priority action 4: Manage exploitation of species
and riverine aggregates
Priority action 6: Safeguard and restore freshwater
SDG 14.4: Overfishing Amend and new: Extend target to cover all aquatic ecosystems,
not just marine. Extend timeline to 2030 to encourage
continued effort; include new indicator(s) to track the status of
inland fisheries—for example, proportion of fish stocks within
biologically sustainable levels within inland waters.
Priority action 4: Manage exploitation of species
and riverine aggregates
SDG 15.1: Terrestrial
and inland freshwater
Amend: Strengthen links with SDG 6 by explicit cross-reference
to indicators 6.3.2 (water quality), SDG 6.4.2 (water stress) and
6.6.1 (extent of water-related ecosystems, amended as above).
Priority action 1: Accelerate implementation of
environmental flows
Priority action 3: Protect and restore critical habitats
Note: For simplicity and ease of reference, we have followed the existing architecture of SDGs. If governments agree to restructure these targets
and indicators in 2020, it will be important that the recommendations in the present article are integrated appropriately into the new architecture.
10 BioScience XXXX XXXX / Vol. XX No. X
the few remaining freshwater ecosystems that are largely
unaffected by human development, such as free-flowing
rivers (Grill etal. 2019). Where threats already exist or are
unavoidable, minimizing their impacts will be the next pri-
ority. For instance, ensuring that new dams are sited such
that their impacts on biodiversity hotspots or basin-scale
connectivity are minimized and designed and operated to
facilitate environmental flows will be essential. For eco-
systems that are already degraded, it will be important to
harness “hot moments” (Jay O’Keeffe, Rhodes University,
1 December 2018), such as environmental disasters or
shifting political priorities, that can trigger ecosystem res-
toration opportunities such as dam removal or pollution
reduction (Speed et al. 2016). Although controversial and
open to misapplication (Simonds etal. 2019), offsetting of
the impacts of development might improve the prospects
for biodiversity conservation beyond status quo efforts in
some situations, for instance through removal of existing or
impending threats to one freshwater ecosystem as compen-
sation for infrastructure development on another within the
same jurisdiction.
Multilateral organizations, international NGOs and
the private sector can contribute by supporting local and
national actors to establish appropriate enabling condi-
tions, including improved ecosystem governance, enhanced
options assessments, more sustainable finance flows, capac-
ity building for water resource and wetland managers, and
better monitoring tools (Harwood etal. 2018). For example,
the International Finance Corporation, a multilateral insti-
tution, funded a strategic environmental assessment in
which options were compared for hydropower develop-
ment in Myanmar, as was described above. In Mexico,
the World Wildlife Fund, an international NGO, worked
closely with government agencies to develop the science
that underpinned water allocations for hundreds of rivers
through environmental water reserves (Barrios etal. 2015,
Opperman etal. 2019b). And the private sector, in the form
of multinational textile companies and retailers, played an
important role in the establishment of the Better Cotton
Initiative (
html), which has promoted improved farming practices
in cotton-growing countries such as Pakistan, helping to
reduce use of polluting pesticides and fertilizers (Zulfiqar
and Bopal 2016).
The research community also has an important role to
play. To support international targets and to help govern-
ments and others to gauge the extent to which action is
leading to recovery of freshwater ecosystems, an improved
suite of indicators of global freshwater biodiversity status
is urgently needed. These indicators should be relevant
(i.e., they should provide information salient to each of
the six actions in the plan), repeatable and affordable,
scientifically robust and statistically comparable, scalable
(e.g., to countries or river basins, as well as to the globe),
and sufficiently sensitive to show the impacts of different
policy measures. Research on indicators can build on and
strengthen existing efforts, including the Living Planet
Index (McRae et al. 2017), the Red List Index (Butchart
et al. 2007), the Wetland Extent Trends index (Darrah
et al. 2019), and the Connectivity Status Index for rivers
(Grill etal. 2019). Priorities include more comprehensive,
higher-resolution data on river flows and water levels,
water infrastructure, water quality, and exploitation and
extraction of freshwater species and materials, drawing on
in situ and remote sensing technologies. There remain sub-
stantial gaps in data on freshwater taxa (e.g., approximately
30% of freshwater mollusk species and 40% of decapod
crustaceans are currently classified as data deficient) and
for some freshwater ecosystems (e.g., many of those in
sub-Saharan Africa). Modeling studies are also needed to
aid design of conservation and restoration portfolios by
identifying potential trade-offs and synergies among, for
example, land management, water resources, climate, and
freshwater biodiversity outcomes (Davis etal. 2015, Byers
etal. 2018) and by exploring the relative costs and benefits
of different driver-focused and ecosystem management
The Intergovernmental Science-Policy Platform on
Biodiversity and Ecosystem Services, whose remit includes
evidence assessment and policy advice to inform interna-
tional agreements, can support the Emergency Recovery
Plan by highlighting the need for improved monitoring of
freshwater biodiversity, synthesizing data and encouraging
appropriate government responses to monitoring results,
including, potentially, through a global thematic assess-
ment of freshwater biodiversity (Doug Beard, 17 July 2019).
The Intergovernmental Panel on Climate Change can also
contribute by comprehensively reviewing the scientific evi-
dence of the likely biodiversity implications of interactions
between climate change, water resources, and freshwater
ecosystems. Given the opportunity, the freshwater science
and biodiversity research community can play an important
role by engaging with such assessments and by providing
data and expertise.
The Emergency Recovery Plan presented in this article is
rooted in practical experience across developed and emerg-
ing economies; all the actions we highlight have already been
implemented somewhere in the world. The challenge now is
to transition from ad hoc freshwater conservation and resto-
ration successes to a strategic approach that achieves results
at a far larger scale.
Conservation and restoration measures will only be
effective at this scale if they are based on an understand-
ing of the processes that underpin freshwater ecosystems
and biodiversity and the distinct threats to them, such
as flow modification and connectivity loss. Simplistically
regarding freshwater habitats as a subset of forests or grass-
lands obscures those distinct threats and precludes effective
action. Conversely, carefully designed portfolios of conser-
vation and restoration actions addressing the most critical
Forum XXXX XXXX / Vol. XX No. X BioScience 11
direct threats and drivers can lead to rapid improvements in
the condition of freshwater ecosystems.
The development of a post-2020 global biodiversity
framework provides a once in a generation opportunity
to promote such improvements at scale and to avoid the
irreversible losses of species and habitats that would arise
from continuation of business-as-usual approaches to con-
servation, water resource management, and policy. Given
the dramatic declines in freshwater biodiversity, which far
exceed those observed in terrestrial or marine ecosystems,
policymakers must ensure that the priority actions we have
defined are central to the post-2020 framework. The recom-
mendations we have provided for adjustments to relevant
targets and indicators should guide their decisions. Those
in the conservation science and practitioner communities
who influence policymakers have an important role to play
in conveying this message.
Bending the curve of biodiversity loss will be a long-term
process. For the flora and fauna in our rivers, lakes, and
inland wetlands, adoption of an improved set of targets and
indicators in 2020, and investment in their implementation
in the coming decade, are urgent and critical first steps to
The workshop from which this article emerged was funded
by WWF-UK. The authors are grateful for helpful comments
on drafts of the manuscript from Jackie King, Joakim Harlin,
Hanna Plotnykova, Wada Yoshihide, and Amanda Palazzo.
We also thanks three anonymous reviewers for helpful com-
ments on a draft of the manuscript.
References cited
Abell R, Thieme ML, Revenga C, Bryer M, Kottelat M, Bogutskaya N, Coad
B, Mandrak N, Balderas SC, Bussing W. 2008. Freshwater ecoregions of
the world: A new map of biogeographic units for freshwater biodiversity
conservation. BioScience 58: 403–414.
Acreman, M., Hughes, K., Arthington, A., Tickner, D, Dueñas, M. 2019.
Protected areas and freshwater biodiversity: A novel systematic review
distils eight lessons for effective conservation. Conservation Letters
Acreman M, Arthington AH, Colloff MJ, Couch C, Crossman ND, Dyer F,
Overton I, Pollino CA, Stewardson MJ, Young W. 2014. Environmental
flows for natural, hybrid, and novel riverine ecosystems in a changing
world. Frontiers in Ecology and the Environment 12: 466–473.
American Rivers. 2019. American Rivers Dam Removal Database, version
6. Figshare.
Arlidge WN, Bull JW, Addison PF, Burgass MJ, Gianuca D, Gorham TM,
Jacob C, Shumway N, Sinclair SP, Watson JE. 2018. A global mitigation
hierarchy for nature conservation. BioScience 68: 336–347.
Arthington AH, et al. 2018. The Brisbane Declaration and global action
agenda on environmental flows (2018). Frontiers in Environmental
Science 6: 45.
Balian E, Lévèque C, Segers H. 2008. Freshwater Animal Diversity
Assessment, vol. 595. Springer.
Barrios E, Salinas Rodríguez SA, Martínez A, López Pérez M, Villón
Bracamonte, RA, Rosales Ángeles F. 2015. National Water Reserves
Program in Mexico: Experiences with Environmental Flows and
the Allocation of Water for the Environment. Inter-American
Development Bank.
Bartley D, De Graaf G, ValboJørgensen J, Marmulla G. 2015. Inland
capture fisheries: Status and data issues. Fisheries Management and
Ecology 22: 71–77.
Biggs J, Von Fumetti S, Kelly Quinn M. 2017. The importance of small
waterbodies for biodiversity and ecosystem services: Implications for
policy makers. Hydrobiologia 793: 3–39.
Bonar SA, MercadoSilva N, Hubert WA, Beard Jr TD, Dave G, Kubečka J,
Graeb BD, Lester NP, Porath M, Winfield IJ. 2017. Standard methods for
sampling freshwater fishes: Opportunities for international collabora-
tion. Fisheries 42: 150–156.
Brown C, King J. 2013. Environmental flows in shared watercourses: Review
of assessment methods and relevance in the transboundary setting.
Pages 107–123 in Earle A, Jägerskog A, Öjendal J, eds. Transboundary
Water Management. Earthscan.
Bunn SE. 2016. Grand challenge for the future of freshwater ecosystems.
Frontiers in Environmental Science 4: 21.
Bunn SE, Arthington AH. 2002. Basic principles and ecological conse-
quences of altered flow regimes for aquatic biodiversity. Environmental
Management 30: 492–507.
Butchart SH, Akçakaya HR, Chanson J, Baillie JE, Collen B, Quader S,
Turner WR, Amin R, Stuart SN, Hilton-Taylor C. 2007. Improvements
to the red list index. PLOS ONE 2 (art. e140).
Byers E, Gidden M, Leclère D, Balkovic J, Burek P, Ebi K, Greve P, Grey
D, Havlik P, Hillers A. 2018. Global exposure and vulnerability to
multi-sector development and climate change hotspots. Environmental
Research Letters 13: 055012.
Cairns NA, Stoot LJ, Blouin-Demers G, Cooke SJ. 2013. Refinement of
bycatch reduction devices to exclude freshwater turtles from commer-
cial fishing nets. Endangered Species Research 22: 251–261.
Campos-Silva JV, Peres CA. 2016. Community-based management induces
rapid recovery of a high-value tropical freshwater fishery. Scientific
Reports 6: 34745.
Ceballos G, Ehrlich PR, Dirzo R. 2017. Biological annihilation via the
ongoing sixth mass extinction signaled by vertebrate population losses
and declines. Proceedings of the National Academy of Sciences 114:
Chen A, Wu M. 2019. Managing for sustainability: The development of
environmental flows implementation in China. Water 11: 433.
Cooke SJ, Allison EH, Beard TD, Arlinghaus R, Arthington AH, Bartley
DM, Cowx IG, Fuentevilla C, Leonard NJ, Lorenzen K. 2016. On the
sustainability of inland fisheries: Finding a future for the forgotten.
Ambio 45: 753–764.
Craig LS, Olden JD, Arthington AH, Entrekin S, Hawkins CP, Kelly JJ,
Kennedy TA, Maitland BM, Rosi EJ, Roy AH. 2017. Meeting the chal-
lenge of interacting threats in freshwater ecosystems: A call to scientists
and managers. Elementa: Science of the Anthropocene 5: 72.
Darrah, SE, Shennan-Farpón, Y, Loh, J, Davidson, NC, Finlayson, CM,
Gardner, RC, and Walpole, MJ. 2019. Improvements to the wetland
extent trends (WET) index as a tool for monitoring natural and human-
made wetlands. Ecological Indicators 99: 294–298.
Davidson NC. 2014. How much wetland has the world lost? Long-term and
recent trends in global wetland area. Marine and Freshwater Research
65: 934–941.
Davis J, O’Grady AP, Dale A, Arthington AH, Gell PA, Driver PD, Bond
N, Casanova M, Finlayson M, Watts RJ. 2015. When trends intersect:
The challenge of protecting freshwater ecosystems under multiple land
use and hydrological intensification scenarios. Science of The Total
Environment 534: 65–78.
Death RG, Fuller IC, Macklin MG. 2015. Resetting the river template: The
potential for climaterelated extreme floods to transform river geomor-
phology and ecology. Freshwater Biology 60: 2477–2496.
Dinerstein E, Vynne C, Sala E, Joshi A, Fernando S, Lovejoy T, Mayorga
J, Olson D, Asner G, Baillie J. 2019. A global deal for nature: Guiding
principles, milestones, and targets. Science Advances 5: eaaw2869.
Dixon M, Loh J, Davidson N, Beltrame C, Freeman R, Walpole M. 2016.
Tracking global change in ecosystem area: The wetland extent trends
index. Biological Conservation 193: 27–35.
12 BioScience XXXX XXXX / Vol. XX No. X
Döll P, Bunn SE. 2014. Cross-chapter box on the impact of climate change
on freshwater ecosystems due to altered river flow regimes. Pages
143–146 in Field CB, et al., eds. Climate Change Impacts, Adaptation,
and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of
Working Group II to the Fifth Assessment Report of the Intergovernmental
Panel on Climate Change. Cambridge University Press.
Dudgeon D, etal. 2006. Freshwater biodiversity: Importance, threats, sta-
tus and conservation challenges. Biological Reviews of the Cambridge
Philosophical Society 81: 163–182.
Early R, Bradley BA, Dukes JS, Lawler JJ, Olden JD, Blumenthal DM,
Gonzalez P, Grosholz ED, Ibañez I, Miller LP. 2016. Global threats from
invasive alien species in the twenty-first century and national response
capacities. Nature Communications 7: 12485.
European Commission. 2015. Ecological Flows in the Implementation of
the Water Framework Directive. Office for Official Publications of the
European Communities. Guidance document no. 31. Technical report
no. 2015-086.
European Environment Agency. 2018. Ecological Status of Surface
Water Bodies. European Environment Agency.
[FAO] Food and Agriculture Organization of the United Nations. 2019.
Incorporating Environmental Flows into “Water Stress” Indicator 6.4.2:
Guidelines for a Minimum Standard Method for Global Reporting.
Fricke R, Eschmeyer W, van der Laan R. 2019. Catalog of fishes: Genera,
species, references. California Academy of Sciences. http://researchar-
Funge-Smith S. 2018. Review of the State of the World Fishery Resources:
Inland Fisheries. Food and Agriculture Organization of the United
Nations Fisheries and Aquaculture Circular.
Gallardo B, Clavero M, Sánchez MI, Vilà M. 2016. Global ecological
impacts of invasive species in aquatic ecosystems. Global Change
Biology 22: 151–163.
Gardner R, Finlayson C. 2018. Global Wetland Outlook: State of the World’s
Wetlands and Their Services to People. Ramsar Convention Secretariat.
Grant TR, Lowry MB, Pease B, Walford TR, Graham K. 2004. Reducing
the by-catch of platypuses (Ornithorhynchus anatinus) in commercial
and recreational fishing gear in New South Wales. Proceedings of the
Linnean Society of New South Wales 125: 259.
Grill G, et al. 2019. Mapping the world’s free-flowing rivers. Nature 569:
Grooten M, Almond R. 2018. Living Planet Report 2018: Aiming Higher.
World Wildlife Fund.
Harrison I, Abell R, Darwall W, Thieme ML, Tickner D, Timboe I. 2018.
The freshwater biodiversity crisis. Science 362: 1369.
Harwood A, Johnson S, Richter B, Locke A, Yu X, Tickner D. 2017. Listen to
the River: Lessons from a Global Review of Environmental Flow Success
Stories. World Wildlife Fund.
Harwood A, Tickner D, Richter B, Locke A, Johnson S, Yu X. 2018. Critical
factors for water policy to enable effective environmental flow imple-
mentation. Frontiers in Environmental Science 6: 37.
He F, Zarfl C, Bremerich V, David JN, Hogan Z, Kalinkat G, Tockner K,
Jähnig SC. 2019. The global decline of freshwater megafauna. Global
Change Biology 25: 3883–3892
Hogg RS, Coghlan Jr SM, Zydlewski J, Gardner C. 2015. Fish community
response to a small-stream dam removal in a maine coastal river tribu-
tary. Transactions of the American Fisheries Society 144: 467–479.
Huitema D, Lebel L, Meijerink S. 2011. The strategies of policy entrepre-
neurs in water transitions around the world. Water Policy 13: 717–733.
[ICEM] International Centre for Environmental Management. 2018.
Strategic Environmental Assessment of the Myanmar Hydropower
Sector. ICEM.
Iriarte V, Marmontel M. 2013. River dolphin (Inia geoffrensis, Sotalia flu-
viatilis) mortality events attributed to artisanal fisheries in the Western
Brazilian Amazon. Aquatic Mammals 39: 116.
[IUCN] International Union for Conservation of Nature. 2019. The IUCN
Red List of Threatened Species, version 2019-1. IUCN. www.iucnredlist.
Jones J, Börger L, Tummers J, Jones P, Lucas M, Kerr J, Kemp P, Bizzi S,
Consuegra S, Marcello L. 2019. A comprehensive assessment of stream
fragmentation in Great Britain. Science of the Total Environment 673:
Junk WJ, An S, Finlayson C, Gopal B, Květ J, Mitchell SA, Mitsch WJ,
Robarts RD. 2013. Current state of knowledge regarding the world’s
wetlands and their future under global climate change: A synthesis.
Aquatic Sciences 75: 151–167.
Koehnken L, Rintoul M. 2018. Impacts of Sand Mining on Ecosystem
Structure, Process and Biodiversity in Rivers. World Wildlife Fund
Kok MT, Alkemade R, Bakkenes M, van Eerdt M, Janse J, Mandryk M,
Kram T, Lazarova T, Meijer J, van Oorschot M. 2018. Pathways for
agriculture and forestry to contribute to terrestrial biodiversity conser-
vation: A global scenario-study. Biological Conservation 221: 137–150.
Koning AA. 2018. Riverine Reserves: The Conservation Benefits of
Spatial Protection for Rivers in the Context of Environmental Change.
University of Wisconsin–Madison.
Le Quesne T, Kendy E, Weston D. 2010. The Implementation Challenge:
Taking Stock of Government Policies to Protect and Restore
Environmental flows. WWF and The Nature Conservancy.
Linstead CL. 2018. The contribution of improvements in irrigation effi-
ciency to environmental flows. Frontiers in Environmental Science 6:
Lodge DM, Williams S, MacIsaac HJ, Hayes KR, Leung B, Reichard S,
Mack RN, Moyle PB, Smith M, Andow DA. 2006. Biological inva-
sions: Recommendations for US policy and management. Ecological
Applications 16: 2035–2054.
Lynch AJ, etal. 2016. The social, economic, and environmental importance
of inland fish and fisheries. Environmental Reviews 24: 115–121.
Mace GM, Barrett M, Burgess ND, Cornell SE, Freeman R, Grooten M,
Purvis A. 2018. Aiming higher to bend the curve of biodiversity loss.
Nature Sustainability 1: 448.
McIntyre PB, Reidy Liermann C, Childress E, Hamann EJ, Hogan JD,
Januchowski-Hartley SR, Koning AA, Neeson TM, Oele DL, Pracheil
BM. 2016. Conservation of Migratory Fishes in Freshwater Ecosystems.
Cambridge University Press.
McRae L, Deinet S, Freeman R. 2017. The diversity-weighted living planet
index: Controlling for taxonomic bias in a global biodiversity indicator.
PLOS ONE 12 (art. e0169156).
Moir K, Thieme M, Opperman J. 2016. Securing a Future that Flows: Case
Studies of Protection Mechanisms for Rivers. World Wildlife Fund and
The Nature Conservancy.
NBI (Nile Basin Initiative). 2016. Strategy for Management of Environmental
Flows in the Nile Basin. Nile Basin Initiative Secretariat. 17p.
Noonan MJ, Grant JW, Jackson CD. 2012. A quantitative assessment of fish
passage efficiency. Fish and Fisheries 13: 450–464.
[OECD] Organization for Economic Cooperation and Development. 2017.
Diffuse Pollution, Degraded Waters: Emerging Policy Solutions. OECD.
O’Keeffe JH. 2018. A perspective on training methods aimed at building
local capacity for the assessment and implementation of environmental
flows in rivers. Frontiers in Environmental Science 6: 125.
Olden JD, Konrad CP, Melis TS, Kennard MJ, Freeman MC, Mims MC,
Bray EN, Gido KB, Hemphill NP, Lytle DA. 2014. Are largescale flow
experiments informing the science and management of freshwater
ecosystems? Frontiers in Ecology and the Environment 12: 176–185.
Opperman J, Moyle PB, Larsen EW, Florsheim JL, Manfree AD. 2017.
Floodplains: Processes and Management for Ecosystem Services.
University of California Press.
Opperman J, etal. 2019a. Connected and Flowing: A Renewable Future for
Rivers, Climate, and People. WWF and The Nature Conservancy.
Opperman JJ, Kendy E, Barrios E. 2019b. Securing environmental flows
through system reoperation and management: Lessons from case stud-
ies of implementation. Frontiers in Environmental Science 7: 104.
Forum XXXX XXXX / Vol. XX No. X BioScience 13
Palazzo A, Valin HJP, Batka M, Havlík P. 2019. Investment Needs for Irrigation
Infrastructure along Different Socioeconomic Pathways. World Bank.
Pasko S, Goldberg J, MacNeil C, Campbell M. 2014. Review of harvest
incentives to control invasive species. Management of Biological
Invasions 5: 263–277.
Pastor A, Palazzo A, Havlik P, Biemans H, Wada Y, Obersteiner M, Kabat
P, Ludwig F. 2019. The global nexus of food–trade–water sustaining
environmental flows by 2050. Nature Sustainability 2: 499.
Pimentel D, Zuniga R, Morrison D. 2005. Update on the environmental
and economic costs associated with alien-invasive species in the United
States. Ecological Economics 52: 273–288.
Poff NL, Allan JD, Bain MB, Karr JR, Prestegaard KL, Richter BD, Sparks
RE, Stromberg JC. 1997. The natural flow regime. BioScience 47:
Poff NL, Tharme RE, Arthington AH. 2017. Evolution of environmental
flows assessment science, principles, and methodologies. Pages 203–236
in Horne AC, Webb JA, Stewardson MJ, Richter B, Acreman M, eds.
Water for the Environment. Elsevier.
Rahel FJ, Olden JD. 2008. Assessing the effects of climate change on aquatic
invasive species. Conservation Biology 22: 521–533.
Reid AJ, Carlson AK, Creed IF, Eliason EJ, Gell PA, Johnson PT, Kidd KA,
MacCormack TJ, Olden JD, Ormerod SJ. 2019. Emerging threats and
persistent conservation challenges for freshwater biodiversity. Biological
Reviews 94: 849–873.
Reis V, Hermoso V, Hamilton SK, Bunn SE, Linke S. 2019. Conservation
planning for river–wetland mosaics: A flexible spatial approach to
integrate floodplain and upstream catchment connectivity. Biological
Conservation 236: 356–365.
Reis V, Hermoso V, Hamilton SK, Ward D, Fluet-Chouinard E, Lehner B,
Linke S. 2017. A global assessment of inland wetland conservation sta-
tus. BioScience 67: 523–533.
Sayers P, Galloway G, Penning-Rowsell E, Yuanyuan L, Fuxin S, Yiwei C,
Kang W, Le Quesne T, Wang L, Guan Y. 2014. Strategic flood manage-
ment: Ten “golden rules” to guide a sound approach. International
Journal of River Basin Management 13: 1–15.
Simmonds JS, etal. 2019. Moving from biodiversity offsets to a targetbased
approach for ecological compensation. Conservation Letters (art.
Speed R, Tickner D, Naiman R, Gang L, Sayers P, Yu W, Yuanyuan L,
Houjian H, Jianting C, Lili Y. 2016. River Restoration: A Strategic
Approach to Planning and Management. UNESCO.
Speed R, Yuanyuan L, Zhiwei Z, Le Quesne T, Pegram G. 2013. Basin Water
Allocation Planning: Principles, Procedures and Approaches for Basin
Allocation Planning. UNESCO.
Strayer DL. 2010. Alien species in fresh waters: Ecological effects, interac-
tions with other stressors, and prospects for the future. Freshwater
Biology 55: 152–174.
Strayer DL, Dudgeon D. 2010. Freshwater biodiversity conservation:
Recent progress and future challenges. Journal of the North American
Benthological Society 29: 344–358.
Taylor WW, Bartley DM. 2016. Call to action: The “Rome Declaration”: Ten
steps to responsible inland fisheries. Fisheries 41: 269–269.
Tickner D, Parker H, Oates NE, Moncrieff CR, Ludi E, Acreman M. 2017.
Managing rivers for multiple benefits: A coherent approach to research,
policy and planning. Frontiers in Environmental Science 5: 4.
UN Water. 2018. 2018 UN World Water Development Report, Nature-based
Solutions for Water. United Nations.
[UNEP] United Nations Environment Programme. 2016. Snapshot of the
World’s Water Quality: Towards a Global Assessment. UNEP.
[UNEP] United Nations Environment Programme. 2019. Sand and
Sustainability: Finding New Solutions for Environmental Governance
of Global Sand Resources. UNEP.
UN Environment. 2017. A Framework for Freshwater Ecosystem
Management, vol. 2: Technical Guide for Classification and Target-
Setting. United Nations.
Vaughan IP, Ormerod SJ. 2012. Largescale, longterm trends in B ritish
river macroinvertebrates. Global Change Biology 18: 2184–2194.
Visconti P, Butchart SH, Brooks TM, Langhammer PF, Marnewick D,
Vergara S, Yanosky A, Watson JE. 2019. Protected area targets post-
2020. Science 364: 239–241.
Wu W, Ma B. 2015. Integrated nutrient management (INM) for sustain-
ing crop productivity and reducing environmental impact: A review.
Science of The Total Environment 512: 415–427.
WWAP U. 2017. Wastewater: The Untapped Resource, the United Nations
World Water Development Report. UNESCO.
Zarfl C, Lumsdon AE, Berlekamp J, Tydecks L, Tockner K. 2015. A global
boom in hydropower dam construction. Aquatic Sciences 77: 161–170.
Zulfiqar F, Gopal BT. 2016. Is “better cotton” better than conventional cot-
ton in terms of input use efficiency and financial performance? Land
Use Policy 52: 136–143.
David Tickner ( is the chief freshwater adviser for
WWF-UK, in Woking, United Kingdom. Jeffrey J. Opperman is the global lead
freshwater scientist for the WWF’s Global Science Team, in Washington, DC.
Robin Abell is a freshwater lead for Conservation International, in Arlington,
Virginia. Mike Acreman is the director of Hydroecology Consulting, in
Wallingford, and a fellow of the Centre for Ecology and Hydrology, in
Oxfordshire, United Kingdom. Angela H. Arthington is an emeritus pro-
fessor at the Australian Rivers Institute, at Griffith University, in Nathan,
Queensland, Australia. Stuart E. Bunn is the director of the Australian
Rivers Institute, at Griffith University, in Nathan, Queensland, Australia.
Steven J. Cooke is a Canada research professor of environmental science
and biology for the Fish Ecology and Conservation Physiology Laboratory,
at Carleton University, in Ottawa, Ontario, Canada. James Dalton is the
director of the Global Water Programme for the International Union for
Conservation of Nature (IUCN), in Gland, Switzerland. Will Darwall is the
head of the IUCN Freshwater Biodiversity Unit, Global Species Programme,
in Cambridge, United Kingdom. Gavin Edwards is the global coordina-
tor of Nature 2020 at WWF International, in Woking, United Kingdom.
Ian Harrison is affiliated with the IUCN-SSC Freshwater Conservation
Committee and Conservation International, in Arlington Virgnina. Kathy
Hughes is a freshwater specialist for WWF-UK, in Woking, United Kingdom.
Tim Jones is affiliated with DJEnvironmental, in Harpers Mill, United
Kingdom. David Leclère is a research scholar for the International Institute
for Applied System Analysis, in Laxenburg, Austria. Abigail J. Lynch is a
research fish biologist for the National Climate Adaptation Science Center,
US Geological Survey, in Reston, Virginia. Philip Leonard is the deputy
director of the Freshwater Practice at WWF International, in Woking, United
Kingdom. Michael E. McClain is a professor of ecohydrology at the IHE Delft
Institute for Water Education and with the Delft University of Technology,
in Delft, The Netherlands. Dean Muruven is a policy lead for the Freshwater
Practice of WWF International, in Zeist, The Netherlands. Julian D. Olden
is affiliated with the School of Aquatic and Fishery Sciences at the University
of Washington, in Seattle, Washington. Steve J. Ormerod is a professor of
ecology at the Cardiff School of Biosciences and the Water Research Institute,
at the University of Cardiff, in Cardiff, United Kingdom. James Robinson
is the director of conservation for the Wildfowl and Wetlands Trust, in
Slimbridge, United Kingdom. Rebecca E. Tharme is Director of Riverfutures,
in Cressbrook, United Kingdom. Michele Thieme is a lead freshwater scien-
tist for WWF-US, in Washington, DC. Klement Tockner is affiliated with
the Liebniz Institute of Freshwater Ecology and Inland Fisheries and with
the Institute of Biology at Freie Universität Berlin, in Berlin, Germany. Mark
Wright is the director of science for WWF-UK, in Woking, United Kingdom.
Lucy Young is a science adviser for WWF-UK, in Woking, United Kingdom.
... Conservation practitioners are grappling with the global challenge of accelerating the adoption of conservation initiatives (Tickner et al., 2020;Leclère et al., 2020;Rilov et al., 2020). The adoption of conservation initiatives varies dramatically: some initiatives spread rapidly among potential adopters, but many fail to spread beyond a few initial participants (Mills et al., 2019). ...
... Thus, while we focus on networks derived from freshwater conservation actors, our approaches will be transferable to terrestrial and marine ecosystems. This study was motivated by current efforts to accelerate the implementation of environmental flows (e-flows; Arthington, 2021, Tickner et al., 2020. E-flows describe a broad range of conservation initiatives to restore or design ecologically relevant flow regimes to sustain the structure and function of flowing freshwater systems (Arthington et al., 2018). ...
... Conservation practitioners seeking to use influence maximization to boost the adoption of conservation initiatives should consider key network characteristics. Our network descriptions can help conservation actors better understand network variation at different spatial scales (i.e., local, regional, national) as they attempt to integrate social factors into conservation initiative designs (Harper et al., 2021;Tickner et al., 2020). Indeed, previous work from other disciplines underscores the importance of network topology and structural features for successful diffusion (Minor & Urban, 2008;Ma et al., 2013;Mihara et al., 2015;Sizemore et al., 2019;Edge & Fortin, 2020). ...
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Conservation programs and policies can preserve biodiversity and boost ecosystem services, but only when widely adopted. While thousands of conservation initiatives exist globally, most fail to spread beyond a few initial adopters. Here, we use network science to (1) determine the topology and structure of two networks of conservation actors (one regional, one national), (2) identify influential individuals in those networks, and (3) test whether the adoption of a conservation initiative by influential individuals could increase the spread of that initiative across the network. We find that initial adoption by influential individuals results in sharp improvements in the total number of adopters of a conservation initiative network‐wide, particularly when a linear threshold diffusion model is used. Under an independent cascade diffusion model, the benefits of targeting influencers are smaller but still substantial. These benefits occurred in both networks despite very different network structures: the regional network resembles a random network comprised mostly of state agencies and local entities, while the national network has a scale‐free structure with highly influential hubs of federal agency and NGO entities. Given that many conservation programs fail to reach critical mass, our findings highlight the importance of strategically targeting influential individuals to boost the spread of conservation initiatives. Conservation initiatives can preserve biodiversity and boost ecosystem services, but only when widely adopted. We show using network science that initial adoption of conservation initiatives by influential individuals or organizations can boost overall adoption of the initiative. Given that many conservation programs fail to reach critical mass, our findings highlight the importance of strategically targeting influential individuals to boost the spread of conservation initiatives.
... Dams and diversions are a persistent threat to freshwater biodiversity and ecosystem functioning [1][2][3][4]. Dams cause habitat fragmentation and lead to altered hydrological and water quality regimes that compromise the structure and function of freshwater ecosystems [5,6]. Ecological impacts of dams are widespread, ranging from nutrient declines, loss or change in biodiversity, and the complete reshaping of food webs and energy pathways [7][8][9]. ...
... Freshwater fish are the most diverse group of vertebrates, playing a number of important roles in freshwater ecosystems [10,11], while concurrently rapidly declining across the world [4]. Fragmentation and river regulation by dams remain a central threat to fish biodiversity by altering downstream environmental conditions and blocking migratory paths [12][13][14]. ...
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Dams and diversions are a primary threat to freshwater fish biodiversity, including the loss of species and restructuring of communities, often resulting in taxonomic homogenization (increased similarity) over time. Mitigating these impacts requires a strong scientific understanding of both patterns and drivers of fish diversity. Here, we test whether different components of fish biodiversity have changed in response to major dam construction, and whether these patterns are predictable as a function of key environmental factors in the Gan River Basin, China. The results showed that total and native species alpha diversity have declined from the historical period (pre-dam) to the current period (post-dam). A total of 29 native species are lost, while 6 alien species were gained over time. We found evidence for fish faunal homogenization in the Gan River Basin, with a slight (1%) increase in taxonomic similarity among river basins from the historical period to the current period. Additionally, we revealed significant associations between drainage length, drainage area, and average air temperature, and alpha and beta fish diversity. This study provides new insight into the patterns and drivers of fish biodiversity change in the broader Yangtze River Basin and helps inform management efforts seeking to slow, and even reverse, current trajectories of biodiversity change.
... Domestic sewage and tourism garbage pollution has changed the water quality of the reserve, resulting in a decrease in the sensitive fish species in this study. Therefore, freshwater fish in this study area may be under multiple disturbances, exposing the species to greater risks, so study on the interactions between multiple stressors needs further attention [57][58][59][60]. ...
... Our results demonstrated that the community structure of fish was significantly different among rivers, and environmental filtering was more important than competition in affecting the fish diversity. Similarly, other studies also reported that environmental filtering was the main contributor to the community construction of fish [60,61]. The predominant role of environmental filtering can be attributed to the strong environmental characteristics across rivers. ...
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Freshwater-fish diversity declined rapidly due to multiple anthropogenic disturbances. The loss of fish diversity often manifested itself in taxonomic homogenization over time. Knowledge of multi-faceted diversity (i.e., species, functional, and phylogenetic diversity) perspectives is important for biodiversity assessment and conservation planning. Here, we analyzed the change of the species diversity and phylogenetic diversity of fish in 2008 and 2021 as well as explored the driver factors of the biodiversity patterns in the Lushan National Nature Reserve. The results showed that the species diversity and phylogenetic diversity of fish have declined from 2008 to 2021, with five species lost over time. We found an overall homogenization trend in the fish fauna of the study area, with a 4% increase in taxonomic similarity among the rivers. Additionally, we found that community structure of fish was significantly different among the rivers, and environmental filtering was the main contributor to the phylogenetic diversity of fish in 2008 and 2021. This study provides new insight into the patterns and drivers of fish-biodiversity change in the broader Yangtze River basin and informs management efforts.
... In an era of global environmental pressures and climate change, researchers, conservation organizations, and decision-makers must adopt a large-scale perspective to understand, manage and conserve lakes and reservoirs 3,19,20 . Yet the inconsistency and inaccessibility of data sources across administrative units and lake basins stand in the way of taking such a perspective by precluding seamless analyses at regional to global scales. ...
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Here we introduce the LakeATLAS dataset, which provides a broad range of hydro-environmental characteristics for more than 1.4 million lakes and reservoirs globally with an area of at least 10 ha. LakeATLAS forms part of the larger HydroATLAS data repository and expands the existing datasets of sub-basin and river reach descriptors by adding equivalent information for lakes and reservoirs in a compatible structure. Matching its HydroATLAS counterparts, version 1.0 of LakeATLAS contains data for 56 variables, partitioned into 281 individual attributes and organized in six categories: hydrology; physiography; climate; land cover & use; soils & geology; and anthropogenic influences. LakeATLAS derives these attributes by processing and reformatting original data from well-established global digital maps at 15 arc-second (~500 m) grid cell resolution and assigns the information spatially to each lake by aggregating it within the lake, in a 3-km vicinity buffer around the lake, and/or within the entire upstream drainage area of the lake. The standardized format of LakeATLAS ensures versatile applicability in hydro-ecological assessments from regional to global scales. Measurement(s)hydro-environmental characteristics • lake • water body • hydrographic featureTechnology Type(s)digital curationSample Characteristic - Environmentfreshwater environment • aquatic environmentSample Characteristic - LocationEarth (planet) Measurement(s) hydro-environmental characteristics • lake • water body • hydrographic feature Technology Type(s) digital curation Sample Characteristic - Environment freshwater environment • aquatic environment Sample Characteristic - Location Earth (planet)
... With freshwater biodiversity in decline and recognition that threats are inadequately addressed by policy and management actions (Dudgeon et al., 2006), global biodiversity advocates have called for specific actions to support freshwater biodiversity conservation, including the need to identify and promote freshwater flagship species, such as N. forsteri, in public education programs (Ebner et al., 2016;Tickner et al., 2020;Rees et al., 2021). Granddad the lungfish was a pivotal ambassador for N. forsteri, a species under threat of extinction. ...
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The modern discovery of the Australian lungfish (Neoceratodus forsteri) by European settlers in 1870 was considered one of the most important events in natural history by leading international scientists and naturalists of that time. Its distinct evolutionary lineage and unique extant morphological characteristics fostered the romantic zoological moniker “living fossil”. Although N. forsteri were suspected of being long-lived, a reliable estimate of maximum age has remained elusive. Maximum age is critical to inform wildlife management and conservation efforts, including the use of population viability models. To estimate the maximum age for N. forsteri, we sourced DNA from “Granddad”, the presumed longest-living lungfish known in a zoological park and utilised an epigenetic ageing clock developed for N. forsteri. This lungfish specimen was gifted to the Chicago John G. Shedd Aquarium from Australia in 1933 and lived there for 84 years until death in 2017. We estimated the age of Granddad at death to be 109 years (±6 years), confirming N. forsteri as a true centenarian species. Genotyping also revealed the natal origin of Granddad to be the Burnett River, Queensland, Australia, the location of the species’ original discovery in 1870. We demonstrate the application of novel molecular techniques to a unique long-lived and captive-raised specimen, to improve estimates of maximum age for the species, and to identify natal origin. This information will support future conservation efforts for this iconic yet endangered species.
... However, the functionality of these rivers can be compromised if key processes, such as the transport and distribution of different sediment granulometries in the riverbed, are altered (Wohl, 2005). On a large scale, this loss of functionality can be contextualized in the situation of general degradation suffered by freshwater ecosystems, whose biodiversity is declining dramatically (Tickner et al., 2020). ...
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The ecological impacts of recreational uses on the rivers of Sierra de Guadarrama National Park (SGNP) have been scarcely studied. To assess the impacts of these uses at Las Presillas (an area with small dam along a section of the Lozoya River), and in the Lozoya River (upstream and downstream of the dams), the dynamics of the organic seston (FPOM), physicochemical variables (electric conductivity, dissolved oxygen, Temperature, and pH) and biological variables (fecal coliforms, fecal streptococci, and aquatic macroinvertebrates) during the recreational (July to September) and nonrecreational (October) periods were assessed. The variations observed in the physicochemical parameters were associated with autumnal influence. However, at Las Presillas, different values were found than at the rest of the surveyed sites, characterized by an increase in the concentration of FPOM and, human fecal contamination (although they did not reach dangerous levels) and the response of the macroinvertebrate communities, which resulted in a clear decrease in the IBMWP index and other quality metrics, during the recreational period. These findings suggest that the combined effects of the dams and recreational activities at Las Presillas generate functional dynamics in that alter the habitat in summer. The identification and study of these impacts through the application of innovative indices and quality classes that integrate and contextualize Las Presillas in the SGNP monitoring network, have been identified as key management and conservation tools.
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Abstract Heterogeneity in riverine habitats acts as a template for species evolution that influences river communities at different spatio‐temporal scales. Although birds are conspicuous elements of these communities, the roles of phylogeny, functional traits, and habitat character in their niche use or species' assembly have seldom been investigated. We explored these themes by surveying multiple headwaters over 3000 m of elevation in the Himalayan Mountains of India where the specialist birds of montane rivers reach their greatest diversity on Earth. After ordinating community composition, species traits, and habitat character, we investigated whether river bird traits varied with elevation in ways that were constrained or independent of phylogeny, hypothesizing that trait patterns reflect environmental filtering. Community composition and trait representation varied strongly with increasing elevation and river naturalness as species that foraged in the river/riparian ecotone gave way to small insectivores with direct trophic dependence on the river or its immediate channel. These trends were influenced strongly by phylogeny as communities became more clustered by functional traits at a higher elevation. Phylogenetic signals varied among traits, however, and were reflected in body mass, bill size, and tarsus length more than in body size, tail length, and breeding strategy. These variations imply that community assembly in high‐altitude river birds reflects a blend of phylogenetic constraint and habitat filtering coupled with some proximate niche‐based moulding of trait character. We suggest that the regional co‐existence of river birds in the Himalaya is facilitated by this same array of factors that together reflect the highly heterogeneous template of river habitats provided by these mountain headwaters.
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Optimal design facilitates intelligent data collection. In this paper, we introduce a fully Bayesian design approach for spatial processes with complex covariance structures, like those typically exhibited in natural ecosystems. Coordinate Exchange algorithms are commonly used to find optimal design points. However, collecting data at specific points is often infeasible in practice. Currently, there is no provision to allow for flexibility in the choice of design. We also propose an approach to find Bayesian sampling windows, rather than points, via Gaussian process emulation to identify regions of high design efficiency across a multi-dimensional space. These developments are motivated by two ecological case studies: monitoring water temperature in a river network system in the northwestern United States and monitoring submerged coral reefs off the north-west coast of Australia.
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Loss of habitats or ecosystems arising from development projects (e.g., infrastructure, resource extraction, urban expansion) are frequently addressed through biodiversity offsetting. As currently implemented, offsetting typically requires an outcome of “no net loss” of biodiversity, but only relative to a baseline trajectory of biodiversity decline. This type of “relative” no net loss entrenches ongoing biodiversity loss, and is misaligned with biodiversity targets that require “absolute” no net loss or “net gain.” Here, we review the limitations of biodiversity offsetting, and in response, propose a new framework for compensating for biodiversity losses from development in a way that is aligned explicitly with jurisdictional biodiversity targets. In the framework, targets for particular biodiversity features are achieved via one of three pathways: Net Gain, No Net Loss, or (rarely) Managed Net Loss. We outline how to set the type (“Maintenance” or “Improvement”) and amount of ecological compensation that is appropriate for proportionately contributing to the achievement of different targets. This framework advances ecological compensation beyond a reactive, ad‐hoc response, to ensuring alignment between actions addressing residual biodiversity losses and achievement of overarching targets for biodiversity conservation.
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Protected areas are a global cornerstone of biodiversity conservation and restoration. Yet freshwater biodiversity is continuing to decline rapidly. To date there has been no formal review of the effectiveness of protected areas for conserving or restoring biodiversity in rivers, lakes, and wetlands. We present the first assessment using a systematic review of the published scientific evidence of the effectiveness of freshwater protected areas. Systematic searches returned 2,586 separate publications, of which 44 provided quantitative evidence comprising 75 case studies. Of these, 38 reported positive, 25 neutral, and 12 negative outcomes for freshwater biodiversity conservation. Analysis revealed variable relationships between conservation effectiveness and factors such as taxa assessed, protected area size and characteristics, International Union for Conservation of Nature (IUCN) protected area category, and ecoregion. Lack of effectiveness was attributed to many anthropogenic factors, including fishing (often with a lack of law enforcement), water management (abstraction, dams, and flow regulation), habitat degradation, and invasive non‐native species. Drawing on the review and wider literature we distil eight lessons to enhance the effectiveness of protected areas for freshwater biodiversity conservation. We urge policymakers, protected area managers, and those who fund them to invest in well‐designed research and monitoring programs and publication of evidence of protected area effectiveness.
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Water-management infrastructure, such as dams, diversions, and levees, provides important benefits to society, including energy, flood management, and water supply, but this infrastructure is a primary cause of the decline of freshwater ecosystems and the services they provide. Due to these declines, recent attention has focused on improving the environmental performance of water infrastructure, such as modifying the location, design, or operation of infrastructure to maintain or restore environmental flows. Despite growing attention to the importance of environmental flows, and continued advancement in flow assessment methods, implementation of flow protection or restoration has lagged expectations. In this paper we describe how pursuing environmental flows at the scale of infrastructure systems, rather than individual sites, such as a dam, offers two pathways to increased implementation of environmental flows. First, policy and management mechanisms that apply to large areas—river basins or political jurisdictions—can catalyze large-scale implementation of flow protection or restoration. We provide two examples of system-scale policy and management mechanisms: flow protection policies and system-scale hydropower planning and management. Although system-scale policy and management offer a clear path to large-scale implementation, there will continue to be a need for flow implementation that occurs at smaller scales, such as a high priority river reach. The second pathway focuses on implementation at that scale—such as environmental flow releases from a dam or small set of dams—but embeds dam reoperation or site-scale flow implementation within reoperation of the larger systems of resource management within which the dam or ecosystem is located. These systems of resource management can encompass various sectors and here we provide examples of dam reoperation or flow implementation facilitated by solutions that included changes to the management of (1) water supply systems; (2) floodplains; and (3) irrigation systems. We illustrate both of these system-scale pathways through a set of case studies, drawn primarily from North America, each of which includes an example of current implementation.
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In the face of meeting Sustainable Development Goals for the water–food–energy–ecosystems nexus, integrated assessments are a great means to measure the impact of global change on natural resources. In this study, we evaluate the impact of climate change with the representative concentration pathway 8.5 scenario and the impact of socioeconomics with the shared socioeconomic pathway 2 scenario on land use, water consumption and food trade under four water regulation policy scenarios (invest, exploit, environment and environment+). We used the Global Biosphere Management Model and constrained it with water availability, environmental flow requirements, and water use from agriculture, industry and households (simulated using the Lund–Potsdam–Jena managed Land model, Environmental Policy Integrated Climate model and WaterGap model). Here, we show that an increase in land use by 100 Mha would be required to double food production by 2050, to meet projected food demands. International trade would need to nearly triple to meet future crop demands, with an additional 10–20% trade flow from water-abundant regions to water-scarce regions to sustain environmental flow requirements on a global scale. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.
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Free-flowing rivers (FFRs) support diverse, complex and dynamic ecosystems globally, providing important societal and economic services. Infrastructure development threatens the ecosystem processes, biodiversity and services that these rivers support. Here we assess the connectivity status of 12 million kilometres of rivers globally and identify those that remain free-flowing in their entire length. Only 37 per cent of rivers longer than 1,000 kilometres remain free-flowing over their entire length and 23 per cent flow uninterrupted to the ocean. Very long FFRs are largely restricted to remote regions of the Arctic and of the Amazon and Congo basins. In densely populated areas only few very long rivers remain free-flowing, such as the Irrawaddy and Salween. Dams and reservoirs and their up- and downstream propagation of fragmentation and flow regulation are the leading contributors to the loss of river connectivity. By applying a new method to quantify riverine connectivity and map FFRs, we provide a foundation for concerted global and national strategies to maintain or restore them.
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The Global Deal for Nature (GDN) is a time-bound, science-driven plan to save the diversity and abundance of life on Earth. Pairing the GDN and the Paris Climate Agreement would avoid catastrophic climate change, conserve species, and secure essential ecosystem services. New findings give urgency to this union: Less than half of the terrestrial realm is intact, yet conserving all native ecosystems—coupled with energy transition measures—will be required to remain below a 1.5°C rise in average global temperature. The GDN targets 30% of Earth to be formally protected and an additional 20% designated as climate stabilization areas, by 2030, to stay below 1.5°C. We highlight the 67% of terrestrial ecoregions that can meet 30% protection, thereby reducing extinction threats and carbon emissions from natural reservoirs. Freshwater and marine targets included here extend the GDN to all realms and provide a pathway to ensuring a more livable biosphere.
Freshwater ecosystems are among the most diverse and dynamic ecosystems on Earth. At the same time, they are among the most threatened ecosystems but remain underrepresented in biodiversity research and conservation efforts. The rate of decline of vertebrate populations is much higher in freshwaters than in terrestrial or marine realms. Freshwater megafauna (i.e., freshwater animals that can reach a body mass ≥30 kg) are intrinsically prone to extinction due to their large body size, complex habitat requirements and slow life‐history strategies such as long life span and late maturity. However, population trends and distribution changes of freshwater megafauna, at continental or global scales, remain unclear. In the present study, we compiled population data of 126 freshwater megafauna species globally from the Living Planet Database and available literature, and distribution data of 44 species inhabiting Europe and the United States from literature and databases of the International Union for Conservation of Nature and NatureServe. We quantified changes in population abundance and distribution range of freshwater megafauna species. Globally, freshwater megafauna populations declined by 88% from 1970 to 2012, with the highest declines in the Indomalaya and Palearctic realms (−99% and −97%, respectively). Among taxonomic groups, mega‐fishes exhibited the greatest global decline (−94%). In addition, freshwater megafauna experienced major range contractions. For example, distribution ranges of 42% of all freshwater megafauna species in Europe contracted by more than 40% of historical areas. We highlight the various sources of uncertainty in tracking changes in populations and distributions of freshwater megafauna, such as the lack of monitoring data and taxonomic and spatial biases. The detected trends emphasize the critical plight of freshwater megafauna globally and highlight the broader need for concerted, targeted and timely conservation of freshwater biodiversity.
Artificial barriers are one of the main threats to river ecosystems, resulting in habitat fragmentation and loss of connectivity. Yet, the abundance and distribution of most artificial barriers, excluding high-head dams, is poorly documented. We provide a comprehensive assessment of the distribution and typology of artificial barriers in Great Britain, and estimate for the first time the extent of river fragmentation. To this end, barrier data were compiled from existing databases and were ground-truthed by field surveys in England, Scotland and Wales to derive a correction factor for barrier density across Great Britain. Field surveys indicate that existing barrier databases underestimate barrier density by 68%, particularly in the case of low-head structures (<1 m) which are often missing from current records. Field-corrected barrier density estimates ranged from 0.48 barriers/km in Scotland to 0.63 barriers/km in Wales, and 0.75 barriers/km in England. Corresponding estimates of stream fragmentation by weirs and dams only, measured as mean barrier-free length, were 12.30 km in Scotland, 6.68 km in Wales and 5.29 km in England, suggesting the extent of river modification differs between regions. Our study indicates that 97% of the river network in Great Britain is fragmented and <1% of the catchments are free of artificial barriers.
Systematic conservation planning has contributed to the spatial design of reserve networks in river ecosystems by recognizing the importance of maintaining longitudinal connectivity. In the complex and dynamic landscapes of river-floodplain systems, however, it is still challenging to account for the longitudinal and, especially, lateral connections that are relevant to their management. Adequate protection of floodplain ecosystems requires accounting for spatio-temporal connectivity among all waterbodies that compose the riverine landscape. In this study we present a new framework to account for both within-floodplain (lateral) and longitudinal river connectivity in freshwater systematic conservation planning. We run four prioritization scenarios comparing different rules of connectivity for the rivers and floodplains of the entire Amazon River basin. The scenarios involved the comparison of local protection only versus integrated upstream protection for floodplains. The spatial framework combined two types of planning units, with connectivity between them assessed using two distance-based measures for within-floodplain and upstream-downstream connectivity. We found different levels of protection afforded to floodplain wetlands across scenarios. The scenario including only within-floodplain connectivity failed to detect the propagation of impacts from the surroundings and upstream catchment. In contrast, the scenario that integrated within-floodplain and longitudinal river connectivity agglomerated subcatchments around the priority wetlands, generating catchment-integrated units that efficiently reduced impacts. We also demonstrate that the integrated connectivity can be manipulated to meet different conservation objectives. The new approach presented here offers more ecologically meaningful protection to floodplains because it considers local wetland boundaries and connectivity within wetland complexes together with connectivity with the upstream landscape. This framework can be applied to integrated wetland conservation and management throughout the world and provide a valuable tool to safeguard the ecosystem functioning of complex river-floodplain mosaics.