Amphibian trophic ecology in increasingly human-altered wetlands (original) (raw)
Related papers
. López et al. Amphibian trophic ecology in increasingly human-altered wetlands. HCB
Habitat destruction and alteration are among the major causes of worldwide amphibian declines. Resource limitation in altered environments can potentially affect trophic ecology of amphibians and contribute to decline. In this work, we analyzed changes in resource availability and use, and the population abundance of eight amphibian species from six wetlands that differ in type and degree of human disturbance. Food resource availability varied among sites and the occurrence of some arthropods was correlated with type of disturbance regime. Diet evenness, richness, and niche breadth were similar among sites or months. Nevertheless, diet composition showed significant variation among samples for all species. Diet composition changes among populations were correlated with resource availability in four species (Lysapsus limellum, Dendropsophus nanus, Hypsiboas pulchellus and H. punctatus), but not in the remaining species (D. sanborni, H. raniceps, Scinax nasicus and S. squalirostris). These results suggest that species that are able to adjust their diets according to prey availability may have an adaptive advantage in changing environments associated with anthropogenic disturbances. Given the increasing rate of alteration of wetlands by urbanization, agriculture, and livestock grazing, understanding trophic processes in these habitats is important for preserving the great biodiversity living in these habitats.
A Place to Call Home: Amphibian Use of Created and Restored Wetlands
International Journal of Ecology, 2012
Loss and degradation of wetland habitats are major contributing factors to the global decline of amphibians. Creation and restoration of wetlands could be a valuable tool for increasing local amphibian species richness and abundance. We synthesized the peer-reviewed literature addressing amphibian use of created and restored wetlands, focusing on aquatic habitat, upland habitat, and wetland connectivity and configuration. Amphibian species richness or abundance at created and restored wetlands was either similar to or greater than reference wetlands in 89% of studies. Use of created and restored wetlands by individual species was driven by aquatic and terrestrial habitat preferences, as well as ability to disperse from source wetlands. We conclude that creating and restoring wetlands can be valuable tools for amphibian conservation. However, the ecological needs and preferences of target species must be considered to maximize the potential for successful colonization and long-term persistence.
The Journal of Wildlife Management, 2013
Among the many causes linked to amphibian declines, habitat loss and alteration remain the most significant. Lack of federal protection for isolated wetlands has resulted in loss of amphibian breeding habitat without subsequent mitigation. Additionally, wetlands built for mitigation often do not replicate lost natural wetlands in structure or ecological processes. The long-term role of constructed wetlands for amphibian conservation is poorly understood because monitoring is often lacking. Our objective was to compare amphibian communities of natural wetlands to 2 types of constructed wetlands in the Daniel Boone National Forest, Kentucky. We measured habitat variables including canopy closure, hydrology, upland coarse woody debris, aquatic vegetation, maximum water depth, and Ohio Wetland Rapid Assessment Score at each wetland and quantified species-specific amphibian capture per unit effort using dip-netting. Wood frogs (Lithobates sylvaticus) and marbled salamanders (Ambystoma opacum) were almost exclusively found in natural, ephemeral wetlands, whereas large frogs (L. clamitans, L. catesbeianus, L. palustris) were primarily found breeding in permanent, constructed wetlands. Permutational analysis of variance indicated significant differences in amphibian communities between constructed and natural wetland types. Redundancy analysis indicated that hydrology and canopy closure best explained the differences in community composition between natural and constructed wetlands. Regression analyses and subsequent model ranking showed that greater captures per unit effort for eastern newts (Notopthalmus viridescens) and green frogs (L. clamitans) were predicted by increasing wetland size and depth, respectively, whereas mole salamanders (Ambystoma sp.) were negatively associated with the amount of aquatic vegetation and positively associated with wetland depth. As amphibian conservation and management become increasingly important in light of recent population declines and habitat loss, the ability to construct wetlands that provide amphibian habitat and to monitor how amphibians respond will be crucial to preservation of species diversity. Our research underscores the need for monitoring constructed wetlands to assess ecological condition. We provide suggestions to land managers who aim to construct isolated wetlands for amphibians. ß 2013 The Wildlife Society.
Wetlands Ecology and Management, 2005
Under£401 and£404 of the Clean Water Act, permission to degrade existing natural wetlands in the USA may be conditional on restoring or creating "replacement" wetlands. Success of wetland mitigation efforts in adequately replacing lost wildlife habitats depends on our understanding of factors that affect the structure wetland faunal communities. We examined the effects of the presence of predatory fish, shallow vegetated littoral zone, emergent vegetation cover, and wetland age and size on amphibian diversity in 42 replacement wetlands located in the Ohio's Eastern Corn Belt Plains ecoregion. We recorded 13 species of pond-breeding amphibians, and the average local species richness (a-richness) was 4.2 ± 1.7 species per site (range 1-7). There is strong evidence for the positive association between amphibian species richness and presence of a shallow littoral zone, and the negative association with presence of predatory fish. There was no evidence for the association between species richness and age, size, nor the amount of emergent vegetation cover at the study sites. It is estimated that local species richness in wetlands with shallows was 1.76 species higher on average than in wetlands without shallows (95% CI from 0.75 to 2.76). The presence of predatory fish was associated with an average reduction in species richness by an estimated 1.21 species (95% CI from 0.29 to 2.11). Amphibian species associated with forested wetlands were either rare (eastern newt, spotted salamander) or not present at all (marbled salamander, wood frog) in replacement wetlands. We surveyed all replacement wetlands constructed under£401 in Ohio during the past decade, and found that predatory fish were present in 52.4% of the sites and that shallows were absent from 42.7% of the sites. Our results indicate that current wetland replacement practices could have a negative effect on the amphibian diversity within our region.
Wetlands provide critical habitat for a diverse group of organisms and provide important ecosystem services. Despite this, most natural wetlands have been lost to anthropogenic activities, and as a result, wetland construction is common mitigation practice. Therefore, examination of constructed wetland viability in replacing the function of lost wetlands is vital. Our primary objectives were to compare amphibian communities of shallow and deep constructed wetlands to natural wetlands and to identify which wetland characteristics affect species composition. All wetlands were hydrologically isolated and fishless; natural wetlands had an ephemeral hydrology, and constructed wetland hydrology varied from ephemeral to permanent. Overall, constructed wetlands did not sufficiently replicate natural wetlands with respect to the amphibian community. However, two of our constructed wetlands had a drying period and exhibited communities more similar to natural wetlands. Hydroperiod and canopy closure were indicators of amphibian community composition. Many species observed in natural wetlands were rare in shallow constructed and absent in deep constructed wetlands. Additionally, dominant predator species (primarily Lithobates catesbeianus, Lithobates clamitans, and Notophthalmus viridescens) associated with permanent water were more abundant in constructed wetlands. Water depth, pH, and emergent vegetation were lower in natural wetlands. These data influenced land managers to revise construction methods and to renovate deep constructed wetlands by creating gradual slopes, decreasing maximum depth to 20 cm or less, maintaining canopy cover, and decreasing soil compaction to attempt replication of natural wetland hydrology.
Amphibians in a human-altered wetland landscape: water matters, even when there is plenty
Herpetological Journal, 2016
Amphibians play an important role in ecosystems and are one of the most threatened taxa worldwide. In order to protect their populations, it is essential to understand the factors affecting their distribution, abundance and diversity. Baixo Vouga Lagunar is a heterogeneous, human-modified, coastal wetland in north-west Portugal, with seasonal or permanently flooded habitats. We characterised the patterns of distribution, abundance and diversity of amphibians and aimed to identify its environmental drivers. Species richness was best explained by distance to the nearest well, followed by presence of temporary water bodies. Distance to the nearest well was also the most important driver of the composition of local amphibian assemblages, followed by the distance to forested areas. Our results reflect the findings of other studies in the Mediterranean region that have revealed the importance of seasonally available habitats, and stress the need for conservation of natural as well as arti...
Conservation Biology, 2006
Despite the continuing loss of wetland habitats and associated declines in amphibian populations, attempts to translate wetland losses into measurable losses to ecosystems have been lacking. We estimated the potential productivity from the amphibian community that would be compromised by the loss of a single isolated wetland that has been protected from most industrial, agricultural, and urban impacts for the past 54 years. We used a continuous drift fence at Ellenton Bay, a 10-ha freshwater wetland on the Savannah River Site, near Aiken, South Carolina (U.S.A.), to sample all amphibians for 1 year following a prolonged drought. Despite intensive agricultural use of the land surrounding Ellenton Bay prior to 1951, we documented 24 species and remarkably high numbers and biomass of juvenile amphibians (>360,000 individuals; >1,400 kg) produced during one breeding season. Anurans (17 species) were more abundant than salamanders (7 species), comprising 96.4% of individual captures. Most (95.9%) of the amphibian biomass came from 232095 individuals of a single species of anuran (southern leopard frog [Rana sphenocephala]). Our results revealed the resilience of an amphibian community to natural stressors and historical habitat alteration and the potential magnitude of biomass and energy transfer from isolated wetlands to surrounding terrestrial habitat. We attributed the postdrought success of amphibians to a combination of adult longevity (often >5 years), a reduction in predator abundance, and an abundance of larval food resources. Likewise, the increase of forest cover around Ellenton Bay from <20% in 1951 to >60% in 2001 probably contributed to the longterm persistence of amphibians at this site. Our findings provide an optimistic counterpoint to the issue of the global decline of biological diversity by demonstrating that conservation efforts can mitigate historical habitat degradation. Amphibian Biomass and Abundance Gibbons et al. Biomasa y Abundancia de Anfibios Extraordinaria en un Humedal Aislado: Implicaciones para la Conservación de Humedales Resumen: A pesar de la pérdida de hábitats de humedales y las declinaciones asociadas de poblaciones de anfibios, se han realizado pocos intentos para traducir las pérdidas de humedales en pérdidas mensurables en los ecosistemas. Estimamos la productividad potencial de la comunidad de anfibios que se afectaría por la pérdida de un humedal aislado que ha estado protegido de los impactos industriales, agrícolas y urbanos durante losúltimos 54 años. Utilizamos un cerco de desvío en la Bahía Ellentonn, un humedal dulceacuícola de 10 ha en el Río Savannah, cerca de Aiken, Carolina del Sur (E.U.A.), para muestrear todos los anfibios durante 1 año después de una sequía prolongada. A pesar del intensivo uso agrícola del suelo alrededor de la Bahía Ellenton antes de 1951, documentamos 24 especies y números y biomasa de anfibios juveniles notablemente altos (>360,000 individuos; >1,400 kg) en una temporada reproductiva. Los anuros (17 especies) fueron más abundantes que las salamandras (7 especies), y comprendieron 96.4% de las capturas individuales. La mayor parte (95.9%) de la biomasa provino de 232095 individuos de una sola especie de anuro (Rana sphenocephala). Nuestros resultados revelaron que la resiliencia de la comunidad de anfibios a los estresantes naturales y a la alteración histórica del hábitat y la magnitud potencial de la transferencia de biomasa y energía desde los humedales aislados hacia el hábitat terrestre circundante. Atribuimos eléxito post-sequía de los anfibios a una combinación de longevidad de adultos (a menudo > 5 años), la reducción de la abundancia de depredadores y la abundancia de recursos alimenticios para las larvas. Asimismo, el incremento de la cobertura forestal alrededor de la Bahía Ellerton de < 20% en 1951 a > 60% en 2001 probablemente contribuyó a la persistencia de los anfibios a largo plazo en este sitio. Nuestros hallazgos proporcionan un contrapunto optimista al tema de la declinación global de la diversidad biológica al demostrar que los esfuerzos de conservación pueden mitigar a la degradación histórica del hábitat.
Diversity
Wetlands are of great importance for biodiversity and nature conservation, especially geographically isolated wetlands (GIW). Yet literature about the ecological value of such GIW is missing, especially at the edge of the distribution of endangered species such as amphibians. In 2018 and 2022, we monitored amphibian communities in 15 isolated (GIW) and 12 non-isolated (nGIW) ponds by counting individuals using three methods: (1) capturing with hand nets, (2) visual counting, and (3) capturing with fyke traps. The three methods provided similar results, showing the great importance of GIW for amphibians, especially newts, whose abundance was 5–13 times greater in GIW compared to nGIW. The largest numbers of species and individuals (adults and larvae) were found in isolated wetlands (GIW). In non-isolated water bodies (nGIW) where more than 10 individuals of the Chinese sleeper Perccottus glenii, an alien invasive fish, were found, amphibians were not found at all. Importantly, betwee...
Among the many causes linked to amphibian declines, habitat loss and alteration remain the most significant. Lack of federal protection for isolated wetlands has resulted in loss of amphibian breeding habitat without subsequent mitigation. Additionally, wetlands built for mitigation often do not replicate lost natural wetlands in structure or ecological processes. The long-term role of constructed wetlands for amphibian conservation is poorly understood because monitoring is often lacking. Our objective was to compare amphibian communities of natural wetlands to 2 types of constructed wetlands in the Daniel Boone National Forest, Kentucky. We measured habitat variables including canopy closure, hydrology, upland coarse woody debris, aquatic vegetation, maximum water depth, and Ohio Wetland Rapid Assessment Score at each wetland and quantified species-specific amphibian capture per unit effort using dip-netting. Wood frogs (Lithobates sylvaticus) and marbled salamanders (Ambystoma opacum) were almost exclusively found in natural, ephemeral wetlands, whereas large frogs (L. clamitans, L. catesbeianus, L. palustris) were primarily found breeding in permanent, constructed wetlands. Permutational analysis of variance indicated significant differences in amphibian communities between constructed and natural wetland types. Redundancy analysis indicated that hydrology and canopy closure best explained the differences in community composition between natural and constructed wetlands. Regression analyses and subsequent model ranking showed that greater captures per unit effort for eastern newts (Notopthalmus viridescens) and green frogs (L. clamitans) were predicted by increasing wetland size and depth, respectively, whereas mole salamanders (Ambystoma sp.) were negatively associated with the amount of aquatic vegetation and positively associated with wetland depth. As amphibian conservation and management become increasingly important in light of recent population declines and habitat loss, the ability to construct wetlands that provide amphibian habitat and to monitor how amphibians respond will be crucial to preservation of species diversity. Our research underscores the need for monitoring constructed wetlands to assess ecological condition. We provide suggestions to land managers who aim to construct isolated wetlands for amphibians. ß 2013 The Wildlife Society.
1. Habitat loss is a major driver of biodiversity decline worldwide. Temporary waterbodies are especially vulnerable because they are sensitive both to human impact and to climatic variations. Pond-breeding amphibians are often dependent on temporary waterbodies for their reproduction, and hence are sensitive to loss of temporary ponds. 2. Here we present the results of a 5-year study regarding the use of temporary aquatic habitats by amphibians in a hydrologically modified area of Eastern Europe (Romania). The annual number of aquatic habitats varied between 30 and 120. Each aquatic habitat was characterised by a number of variables such as: 'type' (pond, drainage ditch and archaeological ditch), 'hydroperiod' (number of weeks the ponds were filled in a given year), 'depth' (cm), 'area' (m 2 ) and the density of predatory insects ('predation'). The turnover rate for each amphibian species for each wetland was calculated based on the pond occupancy. 3. Eight amphibian species were recorded from the aquatic habitats. Hydroperiod was the most important variable, positively influencing wetland use by amphibians and their reproductive success. Most species preferred drainage ditches for reproduction, and the reproductive success was highest in this habitat type every year. For most of the species, the local extinction rate was higher than the colonisation rate in the first 4 years, but the situation reversed in the last year of the study when wetland use by amphibians sharply increased because of high rainfall. 4. This study confirms the importance for amphibians of maintaining and managing aquatic habitat diversity at small spatial scales. Man-made aquatic habitats such as drainage ditches may be important habitats for amphibians, and this should be considered in restoration activities.