Loss, Restoration and Multiple Values of Wetlands
Where data exists, it has been shown that humans have destroyed 50-87% of the world’s original wetlands1, leaving about 12 million km2 of wetland area2. This alarming loss of wetlands was mostly caused by agricultural and urban development. Stakeholders involved in the conversion of wetlands likely underestimated their value for conservation, cultural, and recreational purposes. We believe that wetland restoration needs to benefit people, including indigenous and non-indigenous communities, and nature in a balanced way that accommodates the diversity of human uses, but also maintains ecosystem function and biodiversity3.
Although some wetlands are too degraded to be restored4, ecosystem services, such as food provision and land stability, can still be rehabilitated in many other wetlands. To halt and potentially reverse wetland degradation, restoration has increasingly moved to the center stage in policy agendas for conservation. River and wetland restoration often takes place in or around urban centers4 where rehabilitated wetlands can improve dwellers’ well-being. However, people and economic interests are concentrated in such urban areas, often located in downstream sections of river basins and along coastlines (see Fig. 3). Therefore, here higher economic, policy, and political pressures may complicate deliberations and make wetland restoration more challenging than, for example, in rural and/or more peripheral areas. In general, restoration projects often fail, stall, or underachieve when they (i) narrowly focus on a few environmental, cultural, and socio-economic benefits4; (ii) lack clearly identified or have static targets; or (iii) promise more than what technology, funding, and management options realistically allow. In this article, we posit that a better incorporation of stakeholder needs into restoration actions might increase the chances of success in two main case studies, the Greater Everglades and the Murray-Darling Basin (MDB). We also provide insights from wetlands in less affluent countries.
The Greater Everglades
To effectively restore major wetlands, conflicts between interests of multiple stakeholders need to be solved and the environmental complexity of these ecosystems understood and managed. The Greater Everglades is a subtropical oligotrophic wetland in South Florida (southeastern USA) comprising vast expanses of inland freshwater marshes, coastal estuaries with dense mangrove forests, and marine environments. After World War II, the “river of grass” (as this wetland has been called)6 has been reduced to about half of its original size by drainage and impoundment for agriculture and urban development. To restore the Everglades, massive-scale hydrologic interventions have been taking place for many years alongside adaptive management to take new knowledge into account and address unforeseen issues7. Here, water needs of human societies and ecosystems have to be reconciled. Restoration has been largely successful in upstream, less populated areas of this wetland. The Kissimmee River Restoration Project has documented the most restoration-derived ecological benefits8 in the Everglades through removal of water control structures and canal backfilling; over 23 km of meandering river channels were reconnected to the river-floodplain network (Fig. 1)9. As a result, physical, chemical, and biological attributes have substantially improved in this region9.
By contrast, restoration in the southern Everglades has been notably delayed due to competing demands for land and water to support urban development and agriculture for a constantly growing human population and economy7. Trade-offs between “getting the water right” and “getting the water quality right” are needed for the Comprehensive Everglades Restoration Plan to succeed at an ever expanding cost (currently estimated as US$ 16.4 billion; (https://evergladesrestoration.gov). This plan includes major rehydration projects to restore water flow under the Tamiami Trail bridge (Fig. 2) that separates Everglades National Park (ENP) from upstream Water Conservation Areas (WCAs). However, phosphorus (P) loading, and thus concentrations, need to be reduced further to prevent the expansion of invasive cattail (Typha spp.) after reflooding7. Moreover, Lake Okeechobee temporarily stores water for the central and southern Everglades, but this shallow, P-enriched lake often rapidly fills with wet-season rains and runoff from the Kissimmee River. To reduce flooding risks to downstream communities, water is periodically released from the lake into coastal estuaries, resulting in recurrent harmful algal blooms10. Overall, too much freshwater flows to the western and eastern coasts (Caloosahatchee and St. Lucie Estuaries) and too little freshwater reaches the southern coast (Ten-Thousand Islands, Florida Bay, and Biscayne Bay) with negative impacts on seagrass and oyster communities, fisheries, and tourism.
In future decades, climate change will create drier or wetter conditions in various parts of the Everglades and contribute to more intense/frequent droughts, high tides exacerbated by sea level rise, and storm surges from hurricanes11. Model scenarios suggest that effective restoration would increase water flows to the Gulf of Mexico from the current ~50% to 79-91% of the historical flow12. However, South Florida’s booming population growth and economic development and its environmental complexity will continue to challenge Everglades restoration, likely to be completed not before 2060 (at least 30 years later than initially expected)13. The complex, but logical and systemic solution is to envision and work towards a less polluting and more sustainable economy in the Everglades watershed.
Sustainability-Driven Mindset and Actions for Everglades Restoration
To succeed in restoring as much of the Everglades as possible, a solution to the conflicts between water quality and water quantity targets and between economic interests need to be found and actioned. South of Lake Okeechobee (Fig. 4), wetland restoration efforts have predominantly focused on water quality. In the early 2000s, as the negative impact of high P loads on flora and fauna became apparent, state and federal agencies set a nutrient criterion of 10-13 ppb (i.e., µg L-1) total P (TP) for surface water quality in the southern Everglades (WCAs and ENP)14. Total P has since been reduced through treatment in large, shallow constructed wetlands (where plants and algae uptake and recycle nutrients), sediment control, run-off reduction, regular canal maintenance, drainage reduction, and the use of crops with low water needs. However, TP concentrations continue to exceed these trigger levels in Lake Okeechobee (~100 ppb) and in the WCAs (~17 ppb)13,15. Therefore, to minimize concerns of adverse ecological impacts in ENP, more and cleaner fresh water needs to be directed to the southern Everglades, and not just in the wet, but also in the dry season, when saltwater intrudes further inland16.
Upstream of Lake Okeechobee, restoration has focused instead on water quantity. A holistic ecological restoration of the whole Greater Everglades may still be possible, if further progress builds on the achievements attained along the Kissimmee River floodplains (Fig. 4) where today freshwater flows more naturally without severe flooding, limited water storage, and drinking water problems9. Nevertheless, ambitious restoration seems incompatible with the current opportunistic urban development model in South Florida7. Important progress has been made, including increased water delivery to ENP through the Tamiami Trail bridge (see Fig. 2) and enhanced water retention in eastern ENP. Moreover, the Florida Senate is supporting the construction of a reservoir south-east of Lake Okeechobee to reduce freshwater releases to the estuaries (and thus mitigate the related ecological and economic impacts), decrease flooding risks, and combat saltwater intrusion (Florida Senate Bill 10, 2017). However, the persistent ‘non-restoration’ actions5 related to urban development, limestone mining, and intensive farming need to be addressed, alongside social and political conflicts over land and water use that still frustrate restoration managers and residents5. By persistently advocating for increased freshwater flows, many forward-looking practitioners, citizens, and organizations are keeping alive the dream of a restored ‘river of grass’. Overall, a more environmentally sustainable South Florida is needed where, among other changes, reducing food waste and cultivating crops with lower requirements for fertilizers and pesticides could help further improve the quality of water and habitats to the benefit of residents, tourists, and wildlife. By fostering and applying a stronger environmental ethic, water managers, engineers, policy makers, and residents can reduce the collective human impacts on, and restore, the Everglades social-ecological system for society and for biodiversity.
The Murray-Darling Basin
The Murray-Darling Basin (MDB; Fig. 5) is the largest watershed in Australia (1,060,000 km2), it includes 16 Ramsar sites18, and has seen an accelerated use of water resources to the point where, by 2013, as much as 83% of water was used for irrigation agriculture19.
The Murray-Darling Basin Plan
While there was debate in the South Australian parliament as early as 1887 over the risk of upstream uptake to water resources in the lower basin20, water abstraction became the principal issue for basin management only after the drought of 1982-‘83. Given the value of water for agricultural productivity and rural prosperity, calls to return water to the environment were highly contested. Reports were therefore commissioned on the state of the waterways21 and the likely benefits of increased environmental flow volumes22. These studies underpinned the 2007 Water Act and the Murray Darling Basin Plan23 that enacted the return of 2,750 GL/yr of flow to the system (see example of freshwater release in Fig. 6), and a further 450 GL, if it could be demonstrated that their rural communities would not experience any hardship. The contest created by the Plan drew widespread public protest and Senate Select Committee hearings into its impact on rural communities to the point that early this year State governments threatened to withdraw from the Plan.
The Need for Complementary Measures
Water quality monitoring in the MDB begun in 1951, and ecological research was scant until the 1970s. This gap in information has been partly filled by paleolimnological approaches used to examine indicators of past wetland condition over periods spanning 100-5,000 years. From radiometric dating, a rapid increase in sedimentation in the wetlands and widespread evidence of salinization and eutrophication was revealed24. Further, a widespread shift in large deep wetlands, from plant-dominated to phytoplankton-dominated systems due to increases in sediment and nutrient influx became evident25. In addition, it was demonstrated26 that inlets from the main channel were a source of the fine sediments that reduced light availability in the water and ferried nutrients into wetlands. Aquatic plant loss negatively impacted crustacean fauna27 and the new infrastructure for water management disrupted river flows and caused a decline in submerged plants and faunal diversity28. Moreover, vulnerable small-bodied fish species were found to be closely associated with dense aquatic vegetation29 and thus allocating water for environmental purposes was shown not to benefit these important small consumers. The historical records revealed that true ecological restoration is unlikely because water quality management has been neglected and because diverting water allocations from irrigators to the environment may not produce ecological benefits commensurate with the costs to communities in the MDB.
The Climate Future
In future decades, the northern MDB’s climate is predicted to become wetter overall due to more intense tropical storms while the Southern Basin may become drier with shorter growing seasons. Overall, the predicted increased incidence of El Niño events may cause more frequent / intense droughts. Therefore, catchment runoff in the MDB may decline by ~25-50% over upcoming decades30. This climate forcing will amplify the contest over water allocations and increase management challenges for wetland ecosystems. Moreover, intense flooding that increases mean flows is likely to decline and thus reduce the hydrological connections between floodplain wetlands and main river channels. Therefore permanent wetlands may become seasonal or intermittent placing pressure on organisms that need extended inundation periods to flourish and recruit juveniles.
A Better Plan
The goal of the MDB Plan is to redeem water volume to resolve various ecological challenges, including the degradation of floodplain wetlands. However, the current plan may fail unless water quality issues are dealt with and aquatic plants and woody debris are re-introduced. Despite the feasibility and local acceptance of these actions, the MDB Plan’s success is hampered by the negative impacts of current measures, such as the reallocation of water from agriculture to the environment, on people’s livelihoods.
To fully succeed, wetland management needs to acknowledge people’s needs and requires an adaptive approach recognizing the diversity of stressors, the long history of degradation, and the prospects of a drier future. Rather than using economic measures to buy water for environmental purposes, the process would benefit from steps that map the measures that can be implemented in the early stages of the restoration processes, while limiting the socio-economic harm to local communities. In the short-term, measures that improve water and habitat quality, and both lateral and longitudinal connectivity, would reap benefits for the river system and attract less conflict. Medium-term planning is then needed to prepare farmers that will receive less water and allow them to adapt and innovate; at the same time, ecological recovery can be reached by providing high quality environmental flows. Ultimately, this restoration approach combines wise use of water resources with water quality and quantity to enable functional and biodiverse wetlands to be restored.
Proposed measures to improve river water quality include:
• containing the return waters from irrigation agriculture where nutrient loads are high;
• managing the use of watercrafts and stabilizing river banks through fencing to limit direct access to rivers by cattle and other domestic grazing animals;
• policing forest production activities in tributary catchments to ensure compliance with codes of practice.
Early results can be maximized through complementary research that determines the origin of the sediment and nutrients that have entered the system over time31 so as to ensure that catchments losing most sediments and nutrients are rescued first (triage approach). Research can also drive a program to establish hydro-ecological requirements of wetlands by determining historical inundation regimes and the desiccation limits of key plant and animal taxa. Engineering works can then be commissioned to artificially water aquatic ecosystems to stimulate their regeneration and ensure the long-term persistence of viable plant and animal propagules. These measures can also be optimized by determining the appropriate representation of wetland types and prioritizing the watering of key sites that will act as permanent wetlands. The communication of an adaptation pathway approach that implements diverse, timely measures is likely to attract community support, as players are invited to make a fair contribution to a basin wide program. These measures will not only enhance local wetland management, but will enable people to adapt to the effects of climate change locally and across the basin32.
Examples from Emerging Countries
In less affluent regions, such as eastern Africa and northern India, restored wetlands can become a critical resource for local people. For example, boat builders in coastal and island communities in Kenya and Tanzania are often forced to remove mangroves from key nursery habitats, thus harming the very wetlands that support the fisheries for which the boats are built33. In addition to supporting food and other resources for local people, restored mangroves effectively recycle nutrients, provide wildlife with habitat, and protect coasts from storms, erosion, and sea level rise34. However, current small scale ‘gardening’ interventions need to be replaced by large-scale, systemic approaches that ameliorate hydrological conditions and assess planting feasibility beforehand, which would help use scarce economic resources more efficiently34. In the 1990s, the vast Chilika coastal lagoon in northeastern India suffered from excessive sediment accumulation due to natural inflows, agriculture, aquaculture, and human settlements in the watershed. These processes narrowed the lagoon mouth and thus reduced its salinity; however, the lagoon has been restored by dredging the lead channel and opening a new mouth, which improved tidal and sediment fluxes, reduced flooding, and increased salinity and thus helped the recovery of seagrass, fish, crab, prawn, and dolphins35. The decision to open a new lagoon mouth was reached through coordination and consultation of local, national, and international stakeholders and this helped alleviate poverty, as fisheries productivity and tourism increased in the restored system35. The mangrove and lagoon examples show how comprehensive and transdisciplinary approaches to wetland restoration can yield positive ecological and socio-economic outcomes in emerging countries. These insights can be useful to understand, if not to improve, wetland restoration in richer countries where deliberations may suffer more from power imbalances between stakeholders than where economic interests are smaller.
Solutions to the Wetland Restoration Problem
The restoration of wetlands needs to benefit human societies and the biodiversity they depend on, for example by preventing soil erosion or purifying water, whilst conserving species. The assessment of restoration success is critical; however, we do not know whether the great majority of restoration projects is working or not4, for example due to shifting baselines in rapidly changing ecosystems and to the difficulty in setting appropriate reference conditions and realistic restoration goals. We do know that effective restoration can be achieved if factors such as landscape, soil and topography, nutrients, disturbance, invasive species, and biodiversity are taken into account36. However, the beneficiaries of wetland restoration need to be identified, and restoration goals determined based on that information.
At the base of any restoration activity, target goals (e.g., wetland salinity and water quality) need to be identified using contemporary and paleoecological research and modelling37,38 in consultation with stakeholders. Key abiotic and biotic variables to assess wetland ecological integrity need to be monitored appropriately, data and information transparently managed, and approaches and findings discussed broadly. Results of natural and social research investigations need to be integrated with indigenous and non-indigenous people’s knowledge, innovation, and practices39. To garner people’s support and so, ultimately, to succeed, wetland restoration needs to bring sustained economic opportunities in the form of jobs that enhance the well-being of people. For example, cultivating crops that require less nutrients and water can improve water quality, while restoring mangroves can boost greenhouse gas sequestration34 and support sectors such as subsistence fisheries and (eco)tourism35, at the same time protecting wildlife.
Fundamental solutions to conflicts between wetland resource management and restoration include framing solutions to problems in a respectful way for all stakeholders involved, avoiding the politicization of key issues (e.g., eutrophication), and complying with and enforcing national, regional, local and international regulations. The Ramsar Convention on Wetlands (https://www.ramsar.org/), the intergovernmental treaty that mandates signatory countries (Parties) to conserve wetlands and ensure the wise use of their resources, also sets principles and guidelines on how to succeed in restoration, e.g. by planning at the catchment level, involving all stakeholders, and using traditional knowledge40. We recommend that independent and authoritative wetland restoration brokers be charged with the task of mediating between stakeholders’ interests to integrate common objectives into restoration best practices. Such brokers would be especially useful in large-scale restoration efforts (e.g., in the Greater Everglades and in the Murray-Darling Basin), so that vulnerable groups can better negotiate viable solutions with more powerful stakeholders and policy-makers. Importantly, enabling democratic, non-coercive deliberation among stakeholders can prevent policy shortfalls that are often caused by people’s biases and distorted perceptions5. Restoration approaches need to account for stakeholder values, assumptions, ideas, interests, and evidence from multidisciplinary researchers from different disciplines. These are best integrated in deliberations on restoration actions in a transdisciplinary way, from the commencement of a project to its completion.
To overcome conflicts and succeed, restoration projects, plans, and programs must take into account historical and existing ecosystem and landscape dynamics and evaluate potential ecological engineering and adaptive management solutions. Taking a river basin perspective may be critical to understanding and managing wetland ecosystems, for example to preserve the wintering habitats of migratory species and/or to foster sustainable development (Fig. 3). Integrated water resource management (IWRM) programs that focus on water rights and pricing in river basins do not always work, especially if ad-hoc small-scale actions are easier and faster to implement41. On the other hand, inter-river basin management can be crucial for wetlands located downstream. For example, the Permanent Okavango River Basin Water Commission (OKACOM; http://www.okacom.org/) coordinates regional water resource development in Angola, Namibia, and Botswana to sustainably manage natural resources upstream and conserve the Okavango Delta, the second largest inland Delta in the world.
Core funding for wetland science, monitoring, and restoration must be maintained or increased to fill any knowledge gaps, witness unforeseen changes, and feed evidence back into practice to ultimately safeguard the vital functions of wetlands. Important projects are near completion; for example, the Kissimmee River Basin Restoration Project in South Florida is expected to be finalized by 2019, at a cost ~ $1 billion to restore flow in 64 km of continuous river channel and increase floodplain wetland area by >5,000 ha9. This success has been possible due to long-term action and foresight on the part of multiple actors, including water managers, conservationists, and scientists. By contrast, only 16-18% of the projects have been financially covered in the Everglades over a half of its original 30-yr timespan13. Increased and diverse funding sources are therefore critical for continued social-ecological research and restoration action. Long-term research funding cycles, such as those U.S. Long Term Ecological Research (LTER; lternet.edu) research programs dedicated to coastal wetlands, need to be continued and strengthened, as we need to uncover and predict the long-term impacts of global environmental change on wetlands42. Such funding needs to be expanded to the International LTER (https://www.ilter.network) and other networks, particularly in less affluent regions subject to rapid economic development. Adequate resources are critical for adaptive management / adaptive restoration actions that take on board developing technologies and approaches43.
Restoration actions may work best if they are integrated into watershed sustainability plans and carried out with a triage approach to save the wetlands that can still be recovered based on priorities agreed upon by all stakeholders. However, a change in mentality is required to shift from nationally-based policy instruments to an internationally agreed framework to set and enforce wetland restoration goals. Currently, the Ramsar Convention signatory Parties assess the effectiveness of their own policies, rules, and actions. The success of wetland restoration activities would be more impartially assessed by knowledge-based standardized and internationally agreed protocols. This is an urgent change to be made, considering that about 40% of the Ramsar Convention Parties are still developing National Wetlands Policies and only about a dozen countries have a wetland-specific policy in place44.
The degradation of wetlands has to be first avoided, then mitigated, and, as a last resort, compensated for by constructing wetlands elsewhere45. Ongoing restoration efforts need to be better integrated into robust sustainability planning of land and water uses, a global challenge for social and environmental researchers, managers, policy makers, and conservationists. Moreover, where and when the economic value of key ecosystem services can be accurately estimated, cost-benefit analyses of any economic activity that supports or hinders wetland restoration need to incorporate such values. On the other hand, the spiritual or existence value of wetlands cannot or should not be valued in economic terms. Therefore, wetlands must be restored not just for their utilitarian value to humans (e.g., food, recreation, and water purification), but because all organisms are deeply connected with water, where evolution by natural selection started, and because nations have globally committed to protecting and using wetlands wisely.
No funding was received for this study. The authors thank Katrina Schwartz and Victor Rivera-Monroy for useful advice and Beth Middleton, Viviana Mazzei, and an anonymous reviewer for their constructive comments on manuscript drafts. This paper was developed in collaboration with the Florida Coastal Everglades Long Term Ecological Research program (National Science Foundation grant #DEB-1237517). This is contribution number 873 from the Southeast Environmental Research Center in the Institute of Water & Environment at Florida International University.
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