Viewpoint:
Freshwater biodiversity encompasses genes, populations, species,
communities, and ecosystems, and provides essential ecosystem services
that are fundamental for human livelihoods and well-being. Freshwater
biodiversity, however, is disproportionately threatened at unprecedented
rates. The most recent Living Planet Report documents on average 84%
decline of abundances of 3,741 monitored populations – representing 944
vertebrate species –in freshwater habitats since 1970, the steepest
decline of any of the major realms: land, oceans, and fresh waters (WWF
2020). Yet, research on and conservation of freshwater biodiversity have
been insufficiently prioritized. Freshwater biodiversity remains
underappreciated relative to marine and terrestrial biodiversity
(Dudgeon et al. 2006; Reid et al. 2019; van Rees et
al. 2020). International and intergovernmental science-policy platforms
and funding agencies continue to fall short of giving freshwater
biodiversity its rightful place in global biodiversity, climate, and
socio-economic forums (Darwall et al. 2018; Tickner et al.2020; Heino et al. 2021), often including freshwater biodiversity
in the terrestrial realm or simply overlooking it.
We propose an agenda to advance freshwater biodiversity research as a
critical step in supporting and improving coordinated action towards its
sustainable management and conservation. Our agenda informs funding
provision, provides guidance to civil society and governmental agencies,
and spurs scientists and policymakers to engage with each other to
support informed global freshwater biodiversity stewardship. Our agenda
does not constitute an exhaustive assessment of all priority needs, nor
does it aim to rank them. Instead we identify fifteen pressing global
needs, grouped into five major research areas to support conservation
and management actions (Fig. 1). The global needs reflect the collective
opinion of the coauthors based on responses to a consultation conducted
in 2020 and described in the supplementary document.
Data infrastructure – Establish and empower
information hubs for the acquisition, mobilization, integration, and
provision of data across all areas of freshwater biodiversity research.
Concrete action steps include:
- Establish a comprehensive compilation of data sources on freshwater
biodiversity that documents their interrelationships. This step is
essential to select a tractable number of efficient outlets and
prioritize the use of existing platforms where metadata are available,
such that robust and verifiable protocols for data processing,
handling, and validation can be implemented.
- Mobilize and make available existing data for the wider research
community by digitizing data from regional and national monitoring
agencies, museum collections, nature conservation associations, and
research institutions, among others. Special attention must be given
to non-English-language sources, which tend to be neglected in global
meta-analyses.
- Develop accessible databases according to the FAIR principles of
Findability, Accessibility, Interoperability, and Reusability
(Wilkinson et al. 2016), in addition to the Nagoya Protocol on
access to genetic resources (Buck & Hamilton 2011).
Monitoring – Strategic programs that efficiently and
comprehensively document the status and trends of development of
freshwater biodiversity are key to research, management, and
conservation. Necessary steps include:
- Coordinate existing freshwater biodiversity monitoring programs to
increase the efficiency of ongoing monitoring activities, develop
probabilistic survey designs to infer the global status of freshwater
biodiversity (Hawkins & Yuan 2016), and enhance integration across
locations (e.g., LTER, GLEON sites).
- Enhance the taxonomy and ecological knowledge of freshwater organisms
to increase coverage of organismal groups and geographical areas.
Special attention to fungi, protists, and other neglected taxa often
described as “hidden biodiversity” (Mlot 2004) is required.
- Develop and improve methodologies to overcome the taxonomic
limitations and inefficiencies of monitoring programs. Such
methodologies include (i) omics, which use DNA, RNA, proteins, and the
full suite of metabolites; (ii) optics, ranging from automated image
analysis or artificial intelligence supported video, to remote-sensing
technologies such as drones and satellites; and (iii) biodiversity
informatics, citizen science, and other emerging approaches to gather
and processing information. Additionally, new developments need to
capture dimensions of freshwater biodiversity beyond taxa diversity,
notably interspecific genetic diversity, species interactions that
modulate biogeographic patterns of species in freshwater communities,
ecosystem functioning and ecosystem services, and habitat diversity.
Ecology – Ecological context is key to conservation and
management, as are the interactions among organisms and the environment
that determine the responses to global change. We advocated developing
research to identify major local, regional, and global drivers affecting
patterns of change in freshwater biodiversity. Required steps includes:
- Further identify relationships among biodiversity, ecosystem
functioning, and nature’s contributions to people. This requires
developing a mechanistic understanding of these relationships,
integrating the multidimensionality of the role of biodiversity in
ecosystem processes, and improving process-based models for freshwater
biodiversity and their contribution to human well-being.
- Establish cause-and-effect relationships to understand and predict the
responses of biodiversity to multiple stressors and the release from
such stressors. Field and system-wide experimentation will be
necessary to achieve this step, coupled with modeling to develop
current and future scenarios and identifying general principals.
- Explore the acclimation, evolutionary, and evasion potentials of
organisms, and the associated ecosystem responses to global change.
Targeted field surveys, combined with coordinated multi-site
experiments through global research networks, will be required. Such
and effort should include large-scale enclosures, exclosures, and
experimental lakes, streams, wetlands, and entire catchments. However,
new and creative funding mechanisms will be crucial to establish and
maintain long-term and large-scale experimental platforms to advance
this research (e.g., AQUACOSM).
Management – Enhance science-based strategies and
methods for sustainable freshwater biodiversity management. Necessary
steps include:
- Improve outcome assessment of restoration measures using large-scale
replication of before-after-control-impact (BACI) designs, including
long-term post-monitoring phases. Meta-analyses of results from
post-monitoring phases will be essential to explain restoration
success and failures and to provide the foundations for a fundamental
rethinking of restoration programs to recover freshwater biodiversity.
- Develop models and projections in line with the scenarios for Nature
Futures (IPBES 2016; Rosa et al. 2017) and promote research
that expands and evaluates nature-based solutions (e.g., constructed
wetlands and riparian buffer strips) for management strategies.
- Develop and test landscape- and catchment-based restoration programs
including lakes, ponds and wetlands, and develop and test
environmentally and ecologically compatible dam schemes to minimize
ecological impacts. Given the current global surge in hydropower dam
construction and planning (Zarfl et al. 2019), biodiversity
research on the impacts of such dams must improve to support
regulatory instruments, preserve the longitudinal connectivity and
migratory corridors, and accompany the sustainable management of
freshwater biodiversity. More broadly, strategies are needed to
enhance blue infrastructures and the associated ecosystem services
provided by both large and small, lentic and lotic freshwater
ecosystems.
Socio-ecology – Considering freshwater biodiversity in its
socio-economic context and societal responses to biodiversity change and
conservation are essential to design conservation implementation
strategies. Proposed steps include:
- Develop solutions for conflicts between biodiversity conservation and
the human use of freshwater ecosystems and their catchments.
Socio-ecological approaches that integrate cultural and societal
practices in knowledge co-production are needed (Norström et
al. 2020). The shifting baseline syndrome (Humphries & Winemiller
2009; Soga & Gaston 2018) needs to be acknowledged when examining how
humans value freshwater biodiversity at present while ensuring its
preservation and restoration for the future.
- Address trade-offs among ecological, economic, and societal targets by
concurrently engaging local communities, scientists and policymakers
to develop adaptive management strategies and measures to protect
freshwater biodiversity. This includes embracing traditional and
indigenous ecological knowledge (Heino et al. 2020).
- Systematically develop citizen science (McKinley et al. 2017;
Fritz et al. 2019) and participatory research to harness the
societal competencies and workforce that extend beyond academia and
government. Developing and sharing methods and designing new
experimental approaches that can be scaled at low cost are critical
aspects for consideration. Additionally, we should place greater
emphasis on engaging dedicated citizen experts (Eitzel et al.2017), a tremendously valuable yet often overlooked resource to
advance freshwater biodiversity research.
In conclusion, we propose an ambitious agenda to initiate and further
support the strategic development of freshwater biodiversity research to
document patterns, processes and changes, and to improve management and
conservation. Our agenda provides a framework for the pressing needs to
counter the unprecedented global challenges faced by freshwater
biodiversity. The proposed steps underscore major research priorities to
cultivate informed global action to protect and sustainably manage
freshwater biodiversity. Research needs and priorities vary regionally,
and the development of regional agendas and priorities are an essential
next step. Clearly, the current freshwater biodiversity crisis requires
defining bold goals and mobilizing substantial resources to meet the
challenges. We call upon scientists, policymakers, and stakeholders to
provide the necessary support for a powerful agenda to protect our fresh
waters, which provide the key resources for the sustainable development
and functioning of our societies.