“Accidental” urban wetlands: ecosystem functions in unexpected places

Abstract

“Accidental” urban wetlands are formed not through deliberate restoration or management activity, but as a product of land use and water infrastructure decisions by municipalities. Often formed in abandoned industrial, residential, or low‐lying commercial areas, where overland flows from storms and municipal water use accumulate, these ecosystems support wetland soils and plant communities. Research that we have conducted in the northeastern and southwestern US suggests that accidental wetlands are capable of counteracting anthropogenic eutrophication, providing habitats for important ecological communities, fostering biodiversity, and mitigating heat. Because the factors contributing to their formation are ubiquitous, accidental wetland systems are likely pervasive in urban landscapes, accounting for a substantial portion of aquatic habitat extent and influencing nutrient and water cycles within cities. They also provide ecosystem services at a fraction of the cost associated with more traditional environmental management efforts.

Artificial Aquatic Ecosystems

“…Some of these accidental features represent failures of water conservation regulation or other damaging abstraction from natural water sources. Nonetheless, left unmaintained, in time, such accidental waterbody construction in relative uplands can "naturalize" to a seemingly "wild" ecosystem [25][26][27]. Waterbodies that humans have constructed accidentally, but that appear relatively free from human intent, are more likely to be regulated than waterbodies that humans have constructed on purpose [23,24].…”

“…Moreover, earth movement has become more common in wet spaces [51], where the potential for accidental creation of waterbodies is higher. Water infrastructure, such as stormwater or water supply pipes, can create accidental wetlands wherever leakage occurs [27]. Accidental creation of aquatic ecosystems is perhaps most likely in abandoned areas, where anthropogenic depressions and impoundments that accumulate water may remain, often with minimal human interference.…”

“…Many artificial waterbodies support species-poor [60] or otherwise undesirable communities or organisms, including disease vectors [58,61,62], and can spread pest species to natural habitats [63,64]. Some have also contributed to, accelerated, or facilitated flow of excess nutrients and other pollutants [65,66], activation of toxicants [58], interrupted desirable species' movement and dispersal [67], increased greenhouse gas emissions [27,68], yielded bad smells [69], and even concealed crime [70]. Other examples of ecosystem disservices proffered by artificial water bodies appear in Table A1.…”

“…Second, artificial aquatic systems are often embedded in intensively used landscapes, potentially exposing them to anthropogenic stressors and disconnecting them from diverse natural populations [13]. Finally, and perhaps most importantly, many artificial aquatic systems may support limited diversity and ecosystem function because they are not designed or managed to do so; in many cases, their intended function may preclude or limit the provision of other services [27]. As a result, scientists, policy-makers, and the general public have tended to accept that artificial aquatic systems will necessarily and inherently have limited value.…”

Designer food webs: from build-it-and-they-will-come to intentionality-in-design

“…Other ecological and successional landscapes may be unintentional, such as median strips or accidental wetlands [5]. Alternatively, homeowners may deliberately introduce a single trophic level (e.g., "butterfly plants") to attract herbivores (e.g., butterflies) and their predators (e.g., birds) to their yards or gardens.…”