Impacts of human‐induced environmental change in wetlands on aquatic animals

Abstract

Many wetlands harbour highly diverse biological communities and provide extensive ecosystem services; however, these important ecological features are being altered, degraded and destroyed around the world. Despite a wealth of research on how animals respond to anthropogenic changes to natural wetlands and how they use created wetlands, we lack a broad synthesis of these data. While some altered wetlands may provide vital habitat, others could pose a considerable risk to wildlife. This risk will be heightened if such wetlands are ecological traps -preferred habitats that confer lower fitness than another available habitat. Wetlands functioning as ecological traps could decrease both local and regional population persistence, and ultimately lead to extinctions. Most studies have examined how animals respond to changes in environmental conditions by measuring responses at the community and population levels, but studying ecological traps requires information on fitness and habitat preferences. Our current lack of knowledge of individual-level responses may therefore limit our capacity to manage wetland ecosystems effectively since ecological traps require different management practices to mitigate potential consequences.We conducted a global meta-analysis to characterise how animals respond to four key drivers of wetland alteration: agriculture, mining, restoration and urbanisation. Our overarching goal was to evaluate the ecological impacts of human alterations to wetland ecosystems, as well as identify current knowledge gaps that limit both the current understanding of these responses and effective wetland management. We extracted 1799 taxon-specific response ratios from 271 studies across 29 countries. Community-(e.g. richness) and population-level (e.g. density) measures within altered wetlands were largely comparable to those within reference wetlands. By contrast, individual fitness measures (e.g. survival) were often lower, highlighting the potential limitations of using only community-and population-level measures to assess habitat quality. Only four studies provided habitat-preference data, preventing investigation of the potential for altered wetlands to function as ecological traps. This is concerning because attempts to identify ecological traps may detect previously unidentified conservation risks. Although there was considerable variability amongst taxa, amphibians were typically the most sensitive taxon, and thus, may be a valuable bio-indicator of wetland quality. Despite suffering reduced survival and reproduction, measures such as time to and mass at metamorphosis were similar between altered and reference wetlands, suggesting that quantifying metamorphosis-related measures in isolation may not provide accurate information on habitat quality.Our review provides the most detailed evaluation to date of the ecological impacts of human alterations to wetland ecosystems. We emphasise that the role of wetlands in human-altered ecosystems can be complex, as they may represent important habitat b...

Stormwater wetlands can function as ecological traps for urban frogs

“…, Sievers et al. ), and while we have clear evidence that these habitats can reduce individual fitness (e.g., Snodgrass et al. , Gallagher et al.…”

“…Although the potential for stormwater wetlands to function as ecological traps has been discussed previously (Tilton 1995, Hale et al 2015a, Sievers et al 2018, and while we have clear evidence that these habitats can reduce individual fitness (e.g., Snodgrass et al 2008, Gallagher et al 2014, we currently lack the necessary information on habitat selection preferences to confirm this. For taxa that lack post-hatching parental care, the selection of oviposition sites is a critical decision that directly affects offspring fitness, and ultimately, population dynamics (Reich and Downes 2004).…”

“…, Sievers et al. ), and survival differed most for the two source wetland pairs with the greatest differences in environmental conditions (Appendix : Fig. S1).…”

The influence of potential stressors on oviposition site selection and subsequent growth, survival and emergence of the non‐biting midge (Chironomus tepperi)

“…C. tepperi are quite resistant to the effects of metal pollution (Hale et al, ), despite larvae inhabiting sediments, but may be more sensitive to other forms of pollution, such as insecticides and herbicides (Phyu, Warne, & Lim, ; Stevens, ). In comparison, frogs, specifically tadpoles, might be sensitive bio‐indicators of environmental alterations to wetlands (Sievers, Hale, Parris, & Swearer, ). More comparisons of the susceptibility of animals with contrasting life histories and behaviors to the same potential ecological traps would help identify which species are most susceptible and why.…”

Using conservation behavior to manage ecological traps for a threatened freshwater fish

“…A potential conflict between the engineered purpose of these wetlands and their use by wildlife, particularly if they function as ecological traps, can therefore arise (Hale et al 2015a). However, the information on behavior and fitness needed to assess whether wetlands are ecological traps is rarely considered (Sievers et al 2018a). However, the information on behavior and fitness needed to assess whether wetlands are ecological traps is rarely considered (Sievers et al 2018a).…”