Wetlands最新文献

Abstract

Wetland management practices often alter habitat characteristics to improve the function of the wetland (e.g., removing emergent vegetation for aesthetics or dredging for fish stocking), potentially at the cost of reducing habitat quality for wetland-dependent species such as freshwater turtles. We identified wetland and surrounding landscape characteristics related to painted turtle (Chrysemys picta) and snapping turtle (Chelydra serpentina) relative abundance and snapping turtle movement among wetlands. We surveyed turtles at 29 wetland sites (0.04–1.71 ha) in a mixed-use watershed in north-central West Virginia, USA, where hardwood forests and wetlands have been heavily fragmented by agriculture and roads. We also applied radio transmitters to 33 adult snapping turtles (17 females and 16 males) across 17 wetlands. Snapping turtle relative abundance was best estimated with mean substrate depth, mean wetland depth, and minimum distance from roads. Painted turtle relative abundance was best estimated with the null model. We documented movement among wetlands for 22 snapping turtles (67%), including 10 females and 12 males. The probability of inter-wetland movement decreased with increased minimum distance from wetlands. Our results suggest that the focal turtle species readily used shallow, mucky wetlands with deep substrate and that increasing the density of wetlands could increase snapping turtle population connectivity. Managers could consider restoring a diversity of wetland types that result in reduced travel distance between wetlands and that collectively have characteristics conducive to multiple species.

Abstract

Fish can act as dispersal vectors for many plant species, and this mutualistic relationship is critical for structuring and regeneration in Amazonian floodable forests. However, anthropogenic threats, such as the deforestation of floodable forests and the overfishing of some species, can disrupt this mutualistic interaction. We investigated the relationship between the size of fish that consume fruits and seeds and the size of seeds retrieved from the fish in the floodable forests. We hypothesize that, in floodable forests, fish with larger body size disperse the larger seeds. A total of 1,054 seeds from 16 plant species were found in the digestive tracts of nine species of frugivorous fish. The length and weight of the fish were positively related with the size of the seeds found in the digestive tracts. The reduction in fish abundance and size may affect dispersal and regeneration, especially of species with larger seeds. Considering the diverse threats to interactions between fish and Amazonian forested wetlands, our study highlights the importance of adequate management of fishery resources and floodable forests for the maintenance of ecosystem services of these environments in the region.

Abstract

The hydroperiod (i.e., the length of time ponded water is present) of prairie potholes is sensitive to climate change. Because snowmelt runoff is the largest contributor to ponded water amounts, a seasonal change in precipitation timing, even when annual amounts are unchanged, can affect wetland hydroperiod. We observed a change in precipitation timing in the Alberta Prairie Pothole Region from 2014 to 2015, though cumulative precipitation amounts were near equivalent. We sought to understand whether this change in precipitation timing could result in (1) a decline in wetland hydroperiod and (2) a change in the community composition of birds, aquatic macroinvertebrates, and plants. Our findings suggest a change in precipitation timing occurred in 2015 (i.e., delayed-precipitation year), which could be tied to a decline in wetland hydroperiod. Wetlands in the delayed-precipitation year were dominated by upland birds and drought-adapted aquatic macroinvertebrates. There was no change in the community composition of plants, and we hypothesize that this may be explained by their ability to use energy stored from the previous year to survive this one-year change in their growing season. We suspect that consecutive declines in hydroperiod year-to-year could shift vegetation communities to being dominated by wet meadow or terrestrial plants; this will ultimately lead to a further reduction of waterbird habitat in the northern PPR – the last refuge for this guild in the PPR.

Common carp (Cyprinus carpio) is an invasive fish species in North America and around the world. Through their feeding and spawning they contribute to the deterioration of wetland habitats. Exclusion structures are a frequently used management option for limiting their negative impacts. While habitat responses to common carp exclusion have been reported, little is known about impacts of exclusion structure operation on native fish assemblages. Here we describe a common carp exclusion project on a large freshwater coastal wetland, Delta Marsh, in south-central Manitoba, Canada. Most fish species, including common carp, overwinter in Lake Manitoba and migrate each spring to feed and spawn in the marsh. Exclusion structures with removeable screens were installed on connecting channels between the lake and marsh and were deemed the best management option to exclude common carp from the marsh. In this paper we contrast relative abundance and mean size of large-bodied fish species between pre- (three years) and post- (six years) exclusion periods, as well as inside and outside the common carp exclusion zone. In addition, we monitored fish migration into the marsh to evaluate initial management recommendations. Using a combination of delayed exclusion screen placement and 70 mm screen openings, we were able to reduce the number of large common carp present in the marsh with minimal impacts on the native fish assemblage. We also provide suggested changes to the timing of screen placement to increase common carp exclusion.

Abstract

Stream restoration includes a number of different approaches intended to reduce sediment and nutrient export. Legacy sediment removal (LSR) and floodplain reconnection (FR) involve removing anthropogenically derived sediment accumulated in valley bottoms to reconnect incised streams to their floodplains. These projects also present an opportunity to create high-quality riparian and wetland plant communities and provide information about the early stages of wetland vegetation development and succession. We surveyed vegetation immediately after restoration at three sites and at three additional sites 1–3 years post-restoration to determine how LSR/FR affects riparian plant communities. Restoration increased the prevalence of hydrophytic herbaceous species at all sites, suggesting these projects successfully reconnected the stream to the floodplain. Pronounced decreases in woody basal area and stem density likely also influenced an increase in native and graminoid species after restoration. Only 16% of the indicator species identified for restored reaches were planted as part of the restoration, suggesting the local seed bank and other seed sources may be important for vegetation recovery and preservation of regional beta diversity. Although vegetation quality increased after restoration in reaches with initially low-quality herbaceous vegetation, vegetation quality did not improve or decreased after restoration in reaches with higher-quality vegetation before restoration. The practice of LSR/FR has the potential to improve the quality of some riparian vegetation communities, but the preservation of high-quality forested areas, even if they are atop legacy sediment terraces, should be considered, particularly if reductions in nutrient export do not offset losses in tree canopy.

Wetlands are a critical habitat for boreal mammals and birds that rely on them for breeding, foraging, and resting. However, wetlands in boreal regions are under increasing natural and human pressure, leading to a reduction in habitat availability for these species. To inform management and conservation of wildlife, camera traps can help investigate habitat preferences. We aimed to evaluate the effect of habitat features on the occupancy of mammals and birds in boreal wetlands, namely beaver ponds and peatland ponds. We used a multispecies occupancy model to estimate the habitat associations of 11 mammals and 45 avian species detected at 50 ponds during the summers of 2018 and 2019 in Northern Quebec. The patterns of habitat response do not lend support to the hypothesis that beaver ponds host higher levels of occupancy of birds and mammals than peatland ponds. Our results suggest that certain mammals, such as Red Fox (Vulpes vulpes) and River Otters (Lontra canadensis), and birds including the American Pipit (Anthus rubescens), Common Raven (Corvus corax), Hooded Merganser (Lophodytes cucullatus), and Greater Yellowlegs (Tringa melanoleuca) preferred peatland ponds, whereas the Common Grackle (Quiscalus quiscula) preferred beaver ponds. We found a few effects of distance to roads, but no effect of amount of forest cover on species occupancy. The occupancy of 27% of mammals and 24% of birds decreased with increasing latitude. These findings offer valuable insights for the preservation of different wetland types and their associated wildlife communities.

Annual induced fires have caused significant changes in the composition and structure of wildlife globally. These events are particularly critical for species with limited mobility and small clutch sizes, such as small and medium-sized freshwater turtles in the tropics. At the same time, this topic has received little attention and has not been documented in countries with a high diversity of freshwater turtles, such as Mexico. In this study, we report the mortality of the red-cheeked mud turtle (Kinosternon scorpioides cruentatum) and the Pacific Coast musk turtle (Staurotypus salvinii) caused by a fire in the north portion of the municipality of Suchiate, Chiapas, Mexico. Specifically, our aims were to (1) register the plant species where the turtles occurred, (2) determine the population structure of each turtle species, and (3) estimate the density, size, and sex ratio of the dead turtles of each species. Additionally, we discuss the potential effects of fire on the demography of these turtles in the study site.

In this study, we evaluated the effect of changes in natural wetlands on the amphibian diversity at differing spatial and temporal scales. We sampled 10 wetland sites along floodplains in southern Brazil. We classified the sites as reference or altered ponds according to the preservation degree and presence of human impact. The amphibian monitoring was conducted through calling surveys performed between 2015/2016 using an automated recording system that identified the calling male species. We identified 23 species, mainly distributed in the families Hylidae (43%) and Leptodactylidae (34.8%). The altered ponds had lower diversity and higher species dominance. Even ponds with the greatest landscape change revealed a high degree of resilience concerning the amphibian species composition. However, only Boana pulchella was dominant in altered ponds and B. pulchella and Pseudopaludicola falcipes were dominant in reference ponds. A reduction of amphibian richness was driven by the expansion of the urban area and loss of flooding areas. From 1999 to 2016 all sampled sites had their wetland area reduced as the surrounding urban area increased, contributing to the combined loss of habitat and reproductive sites of anurans in subtropical wetlands.

Nitrogen and phosphorus concentrations were quantified in interstitial water, soil, and the roots of Cladium jamaicense Crantz from four herbaceous wetlands in southeast Mexico, locally known as sabanas, which are established in the karstic valley of the Holbox fracture system (northern Quintana Roo). We used the physicochemical and hydrogeochemical properties of the water to identify the existence of any relationships between nutrient (nitrogen and phosphorus) concentration and stock, and the hydrogeochemistry of each wetland. The wetlands have different classifications: H1 and H2 are palustrine, H3 is lacustrine, and H4 is estuarine. We found greater total phosphorus mass (mg kg⁻¹) in the roots compared to the soil, which was particularly large in the wetland located at the south end of the western fracture. In general, phosphorus and nitrogen had a trend in the interstitial water and soil in which concentration and mass were higher H1 > H3 > H4, different from H2; these trends were not observed in the soil or roots. The N and P concentrations in the soil and roots were different among the wetlands, with the lowest measured at the site with brackish influence. The results presented in this research allow us to compare the nitrogen and phosphorus that can be stored in tropical karst wetlands and relate them to hydrogeochemistry.

Understanding hydrological processes operating on relatively intact blanket bogs provides a scientific basis for establishing achievable restoration targets for damaged sites. A GIS-based hydrological model, developed to assess restoration potential of Irish raised bogs, was adapted and applied to four relatively intact blanket bogs in Ireland. The Modified Flow Accumulation Capacity (MFAC) model utilised high-resolution topographic data to predict surface wetness, based on climatic conditions, contributing catchment and local surface slope. Modifications to MFAC parameters aimed to account for differences in hydrological processes between raised bogs and blanket bogs. Application of a climatic correction factor accounted for variations in effective rainfall between the four study sites, while monitoring of water table levels indicated a log-linear relationship between MFAC values and summer water table levels and range of water table fluctuations. Deviations from the observed relationship between MFAC and water table levels were associated with hydrological pressures, such as artificial drainage or the occurrence of subsurface macropores (peat pipes), which further lowered summer water tables. Despite being effective as a predictor of relative surface wetness, the relationship between MFAC and ecological variables such as Sphagnum spp. cover proved poor, pointing to the impact of past activities and damage caused by anthropogenic pressures. Findings demonstrated MFAC as an effective tool in predicting surface wetness within blanket bog-covered landscapes, thus proving useful to peatland practitioners in planning and prioritising areas for restoration.