Wetlands最新文献

Littoral wetland plant species such as Typha domingensis and Schoenoplectus californicus both locally called tul provide diverse ecosystem services (ES) in Lake Atitlan. These ES include removal of pollutants, oxygenation, and raw material for handicrafts. Human communities, most of whom are Indigenous Maya, actively steward littoral wetlands informed by their traditional ecological knowledge (TEK). Our goal was to assess the wetland condition in four Maya Tz'utujil communities (Santiago Atitlan, San Pedro, San Juan and San Pablo La Laguna, Guatemala), each with different management practices. We used a four-level wetland condition assessment: (1) littoral vegetation extent measured with remote Sentinel-2 and Google Earth photographs; (2) field plant surveys to measure vegetation structure and plant diversity; (3) wetland stressor assessment (stressors analyzed were land use, non-native macrophyte species [Hydrilla verticillata] and lake-level fluctuations); and (4) interviews with Maya Tz’utujil tuleros, fishers and artisans. Santiago stood out as having the highest cover and number of patches for all three species, reflecting its distinctive characteristics (e.g., lakeshore landforms and extent of wetlands) and the role of Indigenous wetland management. Of the four Maya communities, Santiago and San Juan had healthier wetlands despite being most affected by fluctuations in lake water level, reflecting the value of traditional management practices. Indigenous wetland management, informed by TEK, includes actions that sustain wetlands from stressors and global changes, including tul planting, harvesting, and extraction of non-native invasive macrophytes. Ecological value embedded in Indigenous resource management suggests the need to include these practices in governmental environmental management and policy.

Wetlands in southern Ontario are at risk of degradation and alteration due to human activities. This is a concern because wetlands provide essential habitat for species from a range of taxa, such as birds and anurans (frogs and toads). One wetland-dwelling species whose decline may be linked to loss of wetland wildlife habitat is the muskrat (Ondatra zibethicus). The decline of muskrats may also be linked to declines of other species because muskrats engage in activities that could support taxa such as birds and anurans by increasing habitat heterogeneity. We investigated whether bird and anuran species richness is related to muskrat density or if it is better predicted by land cover variables that describe the wetland and surrounding area at 30 coastal wetlands on Lake Ontario. We estimated bird and anuran species richness using data from the Great Lakes Marsh Monitoring Program and the Great Lakes Coastal Wetland Monitoring Program, and muskrat density based on muskrat house counts. Our results suggest that muskrat activity did not predict richness of anurans or birds overall; however, it did predict richness for the subset of birds that nest in emergent aquatic vegetation. Our results indicate that muskrat abundance in emergent marshes may increase habitat quality for birds that nest in emergent vegetation but may not have a measurable effect on anuran diversity in these same wetlands.

Abstract

With increasing threats from climate change and direct human impacts to coastal systems, vulnerability assessment approaches have been developed to enable prioritisation of management actions. This study reviewed vulnerability assessment literature about saltmarsh, beach and mixed shoreline systems published in English. Literature searches and NVivo software were used to analyse literature available, indicative of patterns and gaps in research. Results showed thirteen different methods used in selected literature to assess vulnerability, and the most commonly used was the indices approach. In saltmarsh systems, most articles employed unique methods rather than repeating established ones, and spatial change methods were rare. The majority of research did not include definitions of vulnerability or an indication of which conceptualisation of vulnerability was being used. Most literature assessed vulnerability to climate change and sea level rise, rather than natural hazards or other human impacts. The mangrove vulnerability assessment literature was far more voluminous relative to applications to beach, saltmarsh or mixed such systems. This review identifies how future research can better assess gaps in knowledge, and progress more unified understanding of coastal vulnerability.

Abstract

Clarifying the conditions in which a species can germinate helps elucidate dispersal and establishment patterns. Conventionally considered a freshwater species, evidence indicates that the invasive Yellow flag iris (Iris pseudacorus), originally from North Africa, East Asia and Europe, tolerates saline conditions. Clarifying how water-dispersed I. pseudacorus seeds respond to seawater immersion is critical to understanding marine dispersal and invasion risk for coastal habitats. Accordingly, we evaluated the impact of salinity on the germination of I. pseudacorus. Using seeds from marine and freshwater I. pseudacorus populations, we assessed how the duration of immersion (15, 30, 60, and 90 days) in varying salinities (0, 13–15, 33–35 practical salinity units [PSU]) affected germination, and whether immersion in freshwater following saline exposure impacted germination or seed viability. Seeds sourced from freshwater consistently outperformed seeds from the marine population. Neither salinity concentration nor immersion duration had a statistically significant impact on germination, and nearly all seeds remained buoyant in marine saltwater (33–35 PSU) for 90 days. Saline immersion and germination conditions inhibited germination unless seeds received a freshwater recovery. The freshwater population of seeds had statistically significantly thicker seed coats, but there was no discernible difference in mean seed weight. Seeds from both populations remained viable after prolonged salinity exposure (90–165 days). We posit that observed differences in germination between the two populations may arise from seed dormancy mechanisms rather than seed fitness. Our results suggest that I. pseudacorus seeds could disperse vast distances through the marine environment, possibly habitat-hopping to reach increasingly suitable ecosystems.

Integrated assessments of wetland hydrologic regimes and other environmental factors are key to understanding the ecology of species breeding in ephemerally flooded wetlands, and reproductive success is often directly linked to suitable flooding regimes, both temporally and spatially. We used high-resolution Light Detection and Ranging (LiDAR) data to develop bathymetric stage–flooded area relationships, predict spatial extent of flooding, and assess vegetation structure in 30 pine flatwoods wetlands. For a subset of wetlands with monitoring wells, we then integrated bathymetric and water level data to create multi-year time series of daily flooded areas. We then related the observed flooded areas to topographic and landscape metrics to develop models predicting flooded extents in wetlands without monitoring wells. We found that stage–area curves varied depending on wetland size and bathymetry, such that a one-cm increase in water depth could generate flooded area increases ranging from hundreds to thousands of square meters. Flooded areas frequently fragmented into discrete flooded patches as wetlands dried, and there was a weak positive correlation between hydroperiod and mean flooded area across multiple years (r = 0.32). To evaluate the utility of using LiDAR-derived data to support the conservation of wetland-breeding species, we combined metrics of flooding and vegetation to map potentially suitable habitat for the imperiled reticulated flatwoods salamander (Ambystoma bishopi). Overall, projects focusing on the ecology of wetland-breeding species could gain a broader understanding of habitat effects from coupled assessments of bathymetry, water level dynamics, and other wetland characteristics.

Abstract

Urbanization and land cover change are significantly affecting the availability of habitats for wildlife worldwide. However, linking species persistence to large-scale habitat changes is challenging, especially when wildlife monitoring data is lacking. In China, the Eurasian otter (Lutra lutra) is a species of conservation concern and is listed as endangered as a consequence of declining populations across the country. Hong Kong is home to a small population of Eurasian otters, which are primarily restricted to a set of wetlands in the inner Deep Bay area. However, the drivers of their historical distribution changes are largely unknown. We combined otter spraint data from 2018 to 2019 with historical records of otter data spanning 1959–2018 to examine otter habitat preference and changes in their distribution, relating this with land cover changes measured by Landsat-5 and Landsat-8 satellite remote sensing in the past (1986 and 1995) and present (2018) using supervised random forest classification. We found that otters showed habitat preference for fish ponds and watercourses, and persisted in areas where fish pond area was more readily available. We also found no significant effect of the extent of land cover changes on otter persistence, suggesting that the species is resilient to some level of fish pond loss and find value in available terrestrial habitats. Our results demonstrate the utility of relating satellite remote sensing data to species distribution data over decadal time scales and highlight the importance of managing terrestrial and wetland habitats for otters and other key species in increasingly urbanized landscapes.

Abstract

Canadian and American waterfowl hunters were surveyed to identify their hunting trip preferences. Respondents were individuals that were now participating or had participated in waterfowl hunting, and most had hunted the majority of the last five years. We identified four latent classes of waterfowl hunters that varied in their preferences for harvest, access effort, length of travel, quantity of waterfowl seen, and the potential for interference/competition. We found a diminishing return associated with the number of waterfowl harvested, and that ‘devoted’ and ‘local’ hunters did not perceive appreciable benefit from harvesting more birds beyond harvesting a single bird. Results highlight the importance of not only considering population size, but also the location of habitat for people and waterfowl. Our results provide waterfowl managers important insights into the heterogeneity of North American waterfowl hunters by highlighting differences in priorities for waterfowl hunting trips. Notably, to address this heterogeneity, managers could consider the balance of objectives, actions and resources designed to satisfy current waterfowl hunters. Managing access to improve the likelihood that hunters will see and have opportunities to harvest some waterfowl has benefit to hunters.

Abstract

Mangrove forests of Biscayne Bay in southeast Florida, USA can sequester pollutants from freshwater inputs. This “filtering” of water minimizes point source discharges through canals, but mangroves may also play an important role in the cycling of plastic pollution that reaches the Bay. The objectives of this study are to determine: 1) The composition of debris in the Bay’s mangroves and 2) How the structure of mangrove forests affects debris distribution. Debris was hypothesized to be more abundant further into the forest due to trapping by vegetation, and mesoplastics (5 mm – 2.5 cm) would be positively correlated to macroplastics (> 2.5 cm) due to fragmentation. Nine transects were surveyed and debris was recorded by size and potential origin. 94.5% of all debris was plastic of which 57.8% were fragments. Negative binomial generalized linear regression was used to relate total plastic and mesoplastic densities to distance from shoreline, elevation, basal area, prop root and pneumatophore cover, and mangrove seedling abundance. Plastic increased with distance from shore and basal area, although the latter was just above the p-value cut-off of 0.05 for mesoplastic (p-value = 0.0513), and was weakly negatively related to prop root coverage. Total plastic was weakly negatively related to red mangrove seedlings and pneumatophore coverage, although these relationships were less clear. Mesoplastic and macroplastic were positively correlated (p-value < 0.05). Selected mangrove forests of Biscayne Bay appear to be sinks for plastic debris, where it accumulates in the interior forest from which it is unlikely to escape.

Wetlands, like any other ecosystem, have important characteristics (hydrology, soil, vegetation) that distinguish them from other ecosystems and allow them to provide vital habitats for insects, fish, birds, and other wildlife. Wetlands in the Wilaya of Oran, Algeria, include the Great Sebkha, the marshes of Macta, Lake Telamine, and the salt pans of Arzew, all known for their rich diversity of fauna and flora, are known worldwide for their ecological importance. The objective of this work is to develop an operational geomatic approach for the delineation, evaluation and use of information on North African wetlands. The Digital Atlas made it possible to highlight another aspect of this significant diversity of wetlands in western Algeria, through a new technique for presenting the results used in a web mapping. In the context of global changes driving a steep erosion of biodiversity, this study shows the importance of wetlands in western Algeria and allows citizens to learn about the richness, beauty and extent of their natural heritage. It contributes to public awareness and provides a valuable assessment and evaluation tool available to decision makers and professionals in the field of nature management and conservation. The findings of this study demonstrate, among other things, that considerable scientific advances of a practical kind may be made in the field of remote sensing. These can potentially be linked to managers' needs for tools to inventory and delineate wetlands and to monitor wetland development and conservation status. The Digital Atlas made it possible to discover another aspect of the consequent diversity of North African wetlands, through a new technique of presenting results in the context of web mapping.

Herbivory can hinder restoration success by limiting the recovery of plant biodiversity. This study investigates whether plant-plant interactions, such as associational defenses, can increase the survival of a palatable species in restoration contexts where herbivory inhibits recovery. Specifically, we investigate the potential of associational defenses by the perennial Nuphar advena (yellow pond-lily) to influence the growth and survival of Zizania aquatica (annual wild rice) in a freshwater tidal marsh restoration where goose herbivory has limited Z. aquatica recovery. Wild rice was planted within exclosures and unfenced control plots located within patches of N. advena or adjacent mudflat. In an additional treatment to test the negative effects of light competition, we planted Z. aquatica in exclosures located within experimental clearings in N. advena patches. We also surveyed grazing pressure on naturally-occurring Z. aquatica within transects that spanned N. advena patches and adjacent mudflat. Based on observational and experimental results, N. advena provided clear protection from grazing for Z. aquatica. However, there was a cost to Z. aquatica growing in N. advena patches– plantings within N. advena had greater mortality and significantly reduced biomass due to low light availability.