Comparing the diversity and composition of waterbird functional traits between natural, restored, and artificial wetlands

Abstract

The restoration of degraded areas and the creation of artificial ecosystems have partially compensated for the continuing loss of natural wetlands. However, the success of these wetlands in terms of the capacity of supporting biodiversity and ecosystem functions is unclear. Research is needed to improve our understanding of the value of restored and constructed wetlands for functional diversity of freshwater fauna. We compared natural, restored, and artificially created wetlands present within the Doñana Natural Space, Spain and valued as important for waterbirds. We evaluated if these wetlands are equivalent in terms of waterbird functional trait diversity and composition, during both the wintering and breeding seasons. We modelled functional diversity measures and functional group species richness describing species diet, body mass, and foraging techniques with generalised linear mixed models in 20 wetlands monitored between 2006 and 2011. We used three different statistical approaches to evaluate the robustness of our results. Artificial wetlands constructed for conservation failed to reach the functional diversity of natural and restored wetlands. Unexpectedly, artificial ponds constructed for fish production performed better, and even exceeded natural wetlands for functional richness during winter. Fish ponds stood out as having a unique functional composition, connected with increase in richness of opportunistic gulls and decrease of species sensitive to high salinity. Overall, the functional structure of breeding communities was more affected by wetland type than wintering communities. Our findings suggest that compensating the loss of natural wetlands with restored and artificial wetlands results in systems with altered waterbird‐supported functions, such as seed dispersal or nutrient cycling. Protection of natural Mediterranean wetlands is vital to maintain the original diversity and composition of waterbird functional traits. Furthermore, restoration must be prioritised over the creation of artificial wetlands, which, even when intended for conservation, may not provide an adequate replacement.

Wetland Restoration with Hydrophytes: A Review

“…In the last two decades, there has been an increasing trend to implement CWs in protected areas, such as national or natural parks in all continents (e.g., in Europa: Italy [ 20 , 21 ], Spain [ 16 , 22 ], Poland [ 23 ]; America [ 24 , 25 ]; Asia [ 26 ]; Africa [ 27 ]; Oceania [ 28 ], etc.). Some authors stress that wetland restoration must be prioritized over the creation of artificial wetlands, because, even when intended for conservation, they may not provide an adequate replacement of, for example, waterbird-supported functions [ 29 ]. However, other authors indicate that the biodiversity of constructed wetlands for wastewater treatment can be enhanced through proper design and management [ 30 ].…”

Seven ecological and technical attributes for biofilm‐based recovery of shorebird populations in intertidal flat ecosystems

“…However, restoration initiatives have had mixed success (Atkinson, 2003;Suding, 2011;Sebastian-Gonzalez and Green 2016). While many studies have targeted specific threats, such as disturbance and invasive species at community and ecosystem scales (Iglecia & Winn, 2021), few have specifically considered intervention in intertidal flat ecosystems (Almeida et al, 2020;Kuwae et al, 2003;Wang et al, 2021). None have fully incorporated the roles of intertidal biofilm -an important, recently discovered food source for small-bodied shorebird species in habitats with various degrees of human intervention (almost natural to artificial habitats) .…”

“…Consequently, interventions in intertidal flat ecosystems were instigated within a broader Japanese programme to conserve aquatic habitat and pro-mote ecosystem services (Chan et al, 2006;Kuwae & Crooks, 2021;. Shorebird usage of artificial habitats such as fish and shrimp ponds, saltpans and rice fields underscores the potential for artificial habitats to serve similar roles as their natural counterparts (Almeida et al, 2020;Dias et al, 2014;Lei et al, 2021;Navedo et al, 2015;Warnock & Takekawa 1995). Here, we define the term 'artificial' to mean sites with clearly intended human interventions, such as restored and newly created habitats, in contrast to 'natural' sites, which may be subject to indirect and/or unintended anthropogenic effects, such as climate change, but are formed without clearly intended human interventions.…”

“…The usage of artificial compared with natural habitats may differ in ecological aspects, such as population sizes of target species (Jackson et al, 2020), functional biodiversity (Almeida et al, 2020) and feeding guild and body size (Lei et al, 2021).…”

Nestedness theory suggests wetland fragments with large areas and macrophyte diversity benefit waterbirds

“…The protection of global waterbirds depends on effective governance (Amano et al., 2018 ). The main problem faced by ecosystem designers is constructing the most suitable artificial wetlands for the survival of waterbirds (Almeida et al., 2020 ). Ensuring that the constructed wetlands promote waterbird diversity and designing wetland management and waterbird protection measures are important tasks entrusted to scientists and managers (Giosa et al., 2018 ).…”