The functioning of shallow lakes and wetlands is sensitive to nutrient inputs, transient stratification and mixing, and changes in water balance. We examined open datasets from two National Ecological Observatory Network (NEON) lakes (PRLA and PRPO), La Salada (Argentina), Mar Menor (Spain), Eymir Lake (Türkiye), and Balaton Lake (Hungary), restricting inference to the resolution of each dataset. Analyses combined hourly density-gradient events, water level and hypsometry, block-bootstrap association models, forward-time machine-learning validation, and atmospheric water-balance pressure for 2030–2049. PRPO and PRLA had 133 and 137 complete stratification events with median durations of 13 and 14 h, respectively; 93.2
Biological invasions are a major driver of wetland change, but some non-native species may also provide resources or habitat for native fauna, creating conservation trade-offs. The mangrove rail Rallus longirostris, a bird typically associated with mangroves, was recorded from the 2000s to the early 2020s using patches of the invasive African tanner grass Urochloa arrecta in subtropical salt marshes of southern Brazil. In 2020, management actions eradicated the invaded patches used by the rail, after which R. longirostris disappeared locally. Here, we use continued monthly field surveys from 2022 to 2026 to evaluate the prediction that R. longirostris would reappear only after reinvasion by U. arrecta and the development of patches large enough to provide suitable structure. Urochloa arrecta reappeared as early as 2021, but R. longirostris was recorded again only from mid-2023 onward, when larger patches had developed. By July 2024, three patches occupied by R. longirostris measured 187 m2, 198 m2, and 1,232 m2, whereas a smaller patch of 62.2 m2 remained unoccupied. The repeated sequence of appearance, disappearance after control, and reappearance after reinvasion strengthens evidence for an association between R. longirostris and the habitat structure provided by U. arrecta. We raise the possibility that observed patch-size pattern reflects a lower patch-size constraint on rail use, but this hypothesis remains to be tested. We also discuss the conservation dilemma posed by an invasive plant that harms native salt-marsh biota while providing habitat for a threatened native bird and propose the ecological trap hypothesis be tested.
Ilex nipponica, an endemic deciduous shrub, typically occurs in wetland forests and other wet habitats. However, its distribution in the alluvial lowlands of the Niigata Prefecture, Japan, remains limited, despite the presence of the large number of wetlands in the region; further, the hydrological and topographic conditions that determine its habitat remain elusive. Therefore, we aimed to elucidate factors limiting its distribution via vegetation surveys, groundwater-level observations, water quality analyses, and ecological niche modeling. Vegetation surveys showed that I. nipponica existed in wetlands dominated by herbaceous species with poorly developed tree layers, or in the shrub layer of Alnus trabeculosa forests. However, these species were not found in A. japonica forests. Hydrological surveys demonstrated that at the occurrence sites, groundwater levels remained high throughout the year, with high dissolved oxygen and low nitrate concentrations. Thus, the habitat of this species is not stagnant wetlands, but wetlands with flowing groundwater. Ecological niche modeling identified channel gradient, elevation, and flow accumulation as the major limiting factors. Additionally, the probability of occurrence was high at sites with channel gradients of approximately 1–2
Plant communities are commonly used to assess ecological condition due to their sensitivity to local environmental factors and the practicality of conducting vegetation surveys. Using a large dataset (41,314 survey plots from 563 wetlands across 12 years), we developed and tested a new plant-based Index of Biotic Condition (pIBC) for coastal wetlands for each of the five Laurentian Great Lakes. The pIBC shares conceptual similarities with Floristic Quality Assessment (FQA) metrics but incorporates species-specific sensitivity and responsiveness to anthropogenic disturbance based on modeled probabilities of occurrence derived from field data. This distinguishes it from traditional FQA metrics, which rely on expert-assigned Coefficients of Conservatism and do not incorporate occurrence probability. We found that each lake-specific version of the pIBC consistently predicted anthropogenic disturbance, as indicated by water quality and surrounding land use. Additionally, comparisons with seven other plant-based metrics showed that the pIBC generally provides greater within-lake sensitivity to water-quality and land-use impacts, providing higher-resolution insight into spatial and temporal variation at the lake scale, which is often the most relevant scale for management decisions. The pIBC was also applicable across wetlands of different hydrogeomorphic types and under different water-level conditions. The pIBC’s strong performance suggests that it is well-suited for assessing coastal wetland condition across sites and within sites through time. Overall, this new index is a conceptually grounded and statistically robust tool for conservation practitioners that is easy to calculate and interpret.
Earlier research on aquatic vegetation in lakes within the Yangtze River Basin focused mainly on long-term degraded lakes such as Chaohu Lake and Taihu Lake, while studies on Liangzi Lake, which has only begun showing notable degradation over the past two decades, remain lacking. Therefore, this study combined remote sensing, field surveys, and indoor germination experiments to investigate the characteristics and driving factors of the aquatic vegetation and its seed bank in Liangzi Lake, reveal the degradation mechanisms of aquatic vegetation, and establish a system for assessment of the restoration potential of the aquatic vegetation seed bank. Results indicate that the aquatic vegetation coverage declined from 62.33
