4.3.4. Monitoring, Learning, and Iteration

One of the criticisms of many restorations is that they require ongoing, often expensive managemen<sup>t</sup> to avoid reverting to a degraded state, which some scientists consider a failure of resilience. Part of the problem with declaring restoration success or failure is that goals for a specific restoration are often unclear and may change through time [145], but for most aquatic restorations are never evaluated [97,146]. Monitoring protocols often focus on easily quantifiable measures that ensure mitigation credit, rather than landscape-scale and long term ecological contributions [124]. Such monitoring designs may not adequately assess what was lost and what was gained. In all, current practices of stream and wetland restoration may not be well configured for learning and for adapting designs to improve environmental outcomes [14]. More broadly, the exclusion of artificial aquatic systems from policy protections eliminates an important motive for monitoring. In the UK, a recent precipitous decline in farm pond numbers and services in the UK sparked conservation concern and action [147]. The U.S. lacks the monitoring data necessary to characterize trends in its small artificial aquatic systems and to respond accordingly.

Moving forward, adaptive management, designed experiments [148], reconciliation ecology [149], and other ecologically based ways of improving designs may change the outlook for deliberate waterbodies. A future increase in the acceptance of novel ecosystems might allow the creation of new types of waterbodies designed to provide similarly novel suites of ecosystem services [10,150]. Even the tendency for less regulation of more highly and accidentally modified [23,29,30] and smaller waterbodies [7,8], particularly in the U.S., constitutes an opportunity; this quality could make them comparatively easy and low-cost systems in which to study, test, and implement novel ecological

design ideas [148,151,152]. Together with the repetitive design and construction of many such waterbodies, like ditches and ponds, the manipulability of artificial aquatic ecosystems makes them prime sites for natural experiments [153] and designed experiments [148]. Irrigation canals can serve as "lotic mesocosms", ideal because of their known histories, predictability, and accessibility [152]. Ditch network structure recently served as a good system within which to model possible alternative stable states in primary producer structure [154]. Science in artificial aquatic ecosystems could contribute substantially to broader ecological theory and practice. While win–win design decisions to support multiple desired ecosystem services and other goals can prove challenging to envision and implement, even in artificial aquatic systems, these waterbodies remain sufficiently understudied that exploration of the many remaining questions around them likely has many win–wins, in terms of furthering both applied and theoretical science, left to yield. We hope that the conceptual structures introduced in this article will assist in future such work.

### **5. Artificiality and Perception of Ecosystem Value**

The concept of artificiality, its associated dichotomy between human and nature, and its connotations for valuation, have deep roots. One of the earliest abstract concepts U.S. children master is the difference between artificial and natural, in terms of origin; they learn to tell whether an object is "made by people or something that people can't make" [155]. Accordingly, Western culture has a long tradition of elaborating upon the natural/artificial dichotomy [156] and including it in value systems [157]. In American history, wild nature provided a divine purpose for European settlers, a spiritual rejuvenation for Romanticists and early conservationists like Muir, a source of strength to manage for technocrats, and a rallying point for complex unity among environmentalists [158]. Today, untouched wilderness "exists nowhere but in the imagination" [157]; every ecosystem is somewhat artificial, ye<sup>t</sup> the concept of pristine wild nature continues to exert a strong pull. A recent psychological study found that subjects preferred environments when told that they were natural [159], perceiving them "less dangerous, cleaner, and more plentiful" than those already exploited by other humans. We argue that research and policy-making about artificial aquatic systems reflects this cultural subordination of artificial things to the natural and wild, inherited from broader contemporary Western culture [159,160].

The past several decades have seen ferocious clashes in environmental philosophy and conservation biology over the role of artificial ecosystems. In the 1980s, prominent ethicists lampooned restoration on the grounds that "faked nature is inferior" in much the same way that an art forgery is inferior because it is "a product of contrivance", lacking "causal continuity with the past" [161], and that man-made natural areas represent "domination, the denial of freedom and autonomy" that defines nature [162]. Some philosophers have since softened this dichotomy, viewing it as a gradient or broadening the criteria that constitute a necessary fidelity to nature [163–165]. While naturalness remains valuable by all standards of environmental ethics, many ethicists increasingly distinguish categories (or dimensions) of naturalness, including "as a physical property of species and ecosystems", such as native biodiversity, and "as a quality of processes that are free of human intervention" [74]. This particular pair of categories, posited as a distillation of values already in wide use, corresponds well with our proposed axes of degree of physical modification and level of intentionality, which U.S. policy tends to reflect [23,29,30].

Discussions of humanity's relation to authentic nature intermingle with and parallel debates within conservation biology and broader environmental science and policy. Proponents of traditional wilderness- and biodiversity-based conservation have reacted with alarm to "new conservation", a loose grouping of movements that include human and socio-economic goals, such as poverty reduction, in their conservation plans [73,166]. While restoration has become a widely accepted practice, novel and designed ecosystems are on the battle lines between "new conservationists" who would like to include them in conservation plans and more traditional conservationists who would not [167]. The difficulty in reconciling these perspectives [168,169] may arise in part from different priorities, i.e., the physical and ecological condition of ecosystems versus their freedom from human intervention, and in part from conflicting views about whether human intervention inherently degrades ecological condition.

### *Interactions between Perception and Condition in Artificial Aquatic Systems*

The presumption that artificial aquatic systems have little ecological value matters because it promotes neglect. People make managemen<sup>t</sup> decisions about aquatic systems not on the basis of perfect factual knowledge of the state of these systems and their impact on the broader hydroscape, but instead upon how they perceive them [170]. Natural aquatic ecosystems in poor condition often retain perceived potential value, which restoration seeks to regain, no matter how little realized value remains [171]. However, traditionally, scientists and policymakers have regarded artificial ecosystems as relatively low in ecological value [71], regardless of their actual function and services (Figure 4). Conversely, a high-functioning artificial system may be overlooked in conservation planning [18]. For example, the 250 km of canals of the North Poudre Irrigation Company near Fort Collins, Colorado, supported 92% of wetland area in the 23,300-hectare service area through leakage. In spite of the ecosystem services these wetlands provide, this leakage is considered an unacceptably inefficient use of a scarce resource, and may cease as irrigation practices change, without considering the value of lost accidental wetlands [17]. Perceived value influences design and management, which, along with any other more direct impacts of artificiality, in turn influence ecological condition (Figure 5). If, as appears prevalent among the ecologically minded, perceived artificiality downgrades perceived value of aquatic ecosystems, and managemen<sup>t</sup> and policy decisions reflect this lower valuation in low expectations and low protections for artificial waterbodies, then assumptions of the low quality status of artificial aquatic systems could be self-fulfilling.

**Figure 4.** Value axes for aquatic ecosystems. The solid line represents a traditional axis for the value of aquatic ecosystems. The dashed lines parse out artificiality from ecosystem services provisioning along this traditional axis.

The divergent consequences of this positive feedback loop may be illustrated by examining water managemen<sup>t</sup> policy in the U.S., where the Clean Water Rule prioritized the exclusion of many artificial aquatic systems from jurisdiction under the Clean Water Act [24]. In contrast, the European Union's 1996 Water Framework Directive resolved to gradually expand protection "to all waters, surface waters and groundwater" [172]. In line with this inclusive view of aquatic ecosystems, pond degradation [173] and loss is a stated conservation concern for the EU [147] and NGOs [174]. Freshwater Habitats Trust's Million Ponds Project aims to "to reverse a century of pond loss, ensuring that once again the UK has

over one million countryside ponds", and claims more than 1000 ponds created in 2008–2012, housing about 50 rare and declining species [175].

Meanwhile, European researchers continue to explore pond conservation measures [82], including managemen<sup>t</sup> options that improve habitat quality in existing ponds [105,176]. Similar research and conservation activity is progressing for British and other European ditches [177,178]. Assuming even modest success of such efforts, the condition of artificial aquatic systems in the EU is likely to improve, while the quality of artificial waterbodies in the U.S. is likely to decline. Europe's example suggests that how people regulate, perceive and manage farm ponds, and other artificial aquatic systems does impact conservation outcomes.

**Figure 5.** Conceptual diagram of the role of artificiality in the managemen<sup>t</sup> and services provided by an aquatic ecosystem. (**a**) the currently prevailing process model depicts an approximation of how environmental scientists appear to typically think of the role of artificiality in impacting ecosystems; (**b**) our proposed replacement suggests that, while artificiality may impact ecosystem function directly through mechanisms ye<sup>t</sup> little elucidated, we are more certain that it impacts the perceived value of ecosystem services. Because perception impacts policy, policy affects reality, and reality impacts perception, this proposed replacement process model for the role of artificiality in aquatic ecosystems sets up a positive feedback loop.

Getting the policy, management, and science around these systems right matters not just ecologically, but for social reasons as well. Under-managed artificial waterbodies, particularly environmentally hazardous ones, may often occur in already at-risk communities. Two well-studied

examples of 20th-century environmental injustice in the United States, in Anniston, Alabama, and Hyde Park, Georgia, both involved predominantly black communities contaminated and sickened in part by ditches bearing water laced with toxic industrial waste [179,180]. Recently, hog waste lagoons associated with industrial swine facilities in eastern North Carolina have proved resistant to regulation despite repeated flooding during hurricanes and tropical storms and persistent strong detrimental effects on the health and quality of life of neighbors, who are disproportionately black and low in income [181,182]. Thus, what artificial aquatic systems go unregulated may say as much about what we socially undervalue as what we ecologically undervalue. Relatedly, the same accidental wetlands that host birds and remove nitrogen in the Salt River in Phoenix, Arizona, provide somewhat unsafe, legally unauthorized sources of water and cool places to rest for homeless people [15,16,27], which calls into question the design of non-aquatic infrastructure whose functions may have been deputized to or externalized on artificial aquatic ecosystems. When science and policy overlooks artificial aquatic systems, it risks overlooking the people impacted by them as well.

### **6. Conclusions—Artificial Aquatic Ecosystems in Hybrid Hydroscapes**

Artificial aquatic systems comprise a substantial, perhaps predominant, and likely enduring component of the modern hydroscape. Because the sheer extent of artificial aquatic ecosystems may, by some measures, increasingly rival that of natural systems, they have the potential to play an important role in both conservation and in the provision of ecosystem services within these hybrid aquatic landscapes. The premise underlying reconciliation ecology [149] is the insufficient extent of relatively undisturbed habitats to preserve anything but a fraction of extant species. In some regions, it may be difficult to enact any sufficiently wide-reaching biodiversity conservation policy without inclusion of artificial systems [183]. Because artificial aquatic systems are interwoven with, rather than separate from, natural elements of the hydroscape, improvements in the condition of artificial systems may benefit natural waterbodies as well [75], or may degrade natural waterbodies through abstraction; the net effect of their creation must account for all of the above. Thus, plans to improve land and water managemen<sup>t</sup> should target artificial aquatic systems as well as those of natural origin [183].

To realize greater socio-ecological benefits from artificial aquatic systems, we need to understand not just their current value, but their possible provisioning of ecosystem services. This understanding will require, first and foremost, better assessments of the extent and condition of artificial aquatic systems. Improving that condition will require that we suspend our conventional assumption that artificial aquatic systems are intrinsically inferior; instead, we need more hypothesis-driven study that evaluates the factors, such as watershed setting, physical structure and design, time, and management, that influence their ecological condition. We will need to move beyond this initial exploration to more thoroughly consider interactions among these drivers and alternative ways of framing the mechanisms underlying artificiality (e.g., physical vs. biological), first conceptually and then through well-controlled studies.

Because the very way we perceive artificial aquatic systems may affect their ultimate condition and value, effective managemen<sup>t</sup> of the modern hybrid hydroscape may require reconsidering cultural norms about the concept of artificiality, even undoing our deeply held notions about a human/nature dichotomy. Environmental scientists, and our cross-disciplinary collaborators, must first take on such efforts in support of our own work, but can also play a role in helping policy-makers and others meet these challenges.

**Funding:** This research was funded by a National Science Foundation Graduate Research Fellowship and Duke University's Nicholas School for the Environment.

**Author Contributions:** Both C.C. and J.B.H. contributed substantially to all aspects of this work. Conceptualization, C.C. and J.B.H.; Investigation, C.C. and J.B.H.; Data Curation, C.C. and J.B.H.; Writing—Original Draft Preparation, C.C. and J.B.H.; Writing—Review and Editing, C.C. and J.B.H.; Visualization, C.C. and J.B.H.; Supervision, J.B.H.; Funding Acquisition, C.C. and J.B.H.

**Acknowledgments:** Thanks to the Duke River Center (labs of James Heffernan, Martin Doyle, Brian McGlynn, and Emily Bernhardt), Duke MediaLab 2014 participants, Dean Urban, Monica Palta, Nancy Grimm, Erick Carlson, Lauren McPhillips, Alex Webster, Danielle Purifoy, Cari Ficken, Marissa Lee, Priscilla Wald, Matthew Taylor, and Daniel Richter for contributing to the development of these ideas. Vector files used in Figure 1 courtesy of the Integration and Application Network, University of Maryland Center for Environmental Science (ian.umces.edu/symbols/).

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.
