Changes in multiple facets of macroinvertebrate alpha diversity are linked to afforestation in a subtropical riverine natural reserve

Effects of different types of land-use on taxonomic and functional diversity of benthic macroinvertebrates in a subtropical river network

Expansion of agricultural and urban areas and intensification of catchment land-use increasingly affect different facets of biodiversity in aquatic communities. However, understanding the responses of taxonomic and functional diversity to specific conversion from natural forest to agriculture and urban land-use remains limited, especially in subtropical streams where biomonitoring programs and using functional traits are still under development. Here, we conducted research in a subtropical stream network to examine the responses of macroinvertebrate taxonomic and functional diversity to different types of land-use in central China. Our results showed that medium body size, univoltine, gill respiration, and slow seasonal development were much higher in natural forest sites, while certain traits related to strong resilience and resistance (e.g., small body size, fast seasonal development, bi-or multivoltine, abundant occurrence in drift, sprawler) dominated in high-intensity agriculture and urbanization sites. We further found that land-use compromised water quality (e.g., increases in total phosphate, conductivity and water temperature) and habitat conditions (e.g., high proportion of sand and silt, gravel, and channel width) accounted for the changes in trait composition based on a combination of RLQ and fourth-corner analysis. Moreover, natural forest sites presented relatively high values of functional richness than other land-use, demonstrating the importance of natural forest maintenance to promote high levels of functional diversity. However, taxonomic diversity indexes showed higher sensitivity to distinguish different types of land-use compared to functional diversity measures. Even so, given that certain trait categories showed significant relationships with specific local environmental stressors, trait-based approaches can provide reliable evidence to diagnose the cause of impairment and complement the results of the taxonomic-based approaches. Our findings support the idea that taxonomic and functional approaches should be integrated in river restoration and land-use management.

Damming affects riverine macroinvertebrate metacommunity dynamics: Insights from taxonomic and functional beta diversity

Understanding ecological processes that drive metacommunity dynamics is essential for elucidating the mechanisms of community assembly and for guiding biodiversity conservation. This is especially important in dammed rivers. Here, we examined the taxonomic and functional beta diversity of macroinvertebrates and their underlying drivers in a dammed tropical river and compared the patterns with those in an adjacent undammed river. We found that both taxonomic and functional beta diversities were higher in the dammed river than in the undammed river across wet and dry seasons. The replacement component contributed most to the overall beta diversity for both taxonomic and functional facets, and this component was higher in the dammed river than in the undammed river. In addition, the taxonomic richness difference component was significantly higher in the dammed river in the dry season, but the functional richness difference component showed no difference between the two rivers and between the two seasons. Environmental filtering was the primary driver of total beta diversity and its replacement component, whereas the richness difference component was mainly explained by spatial factors, but these drivers varied in the dammed river in different seasons. Overall, our results indicated that damming induced changes in physiochemical variables (e.g., temperature, conductivity, and nutrients), accompanied by alterations in flow regime and longitudinal connectivity, increased replacement and loss of taxa or traits. These changes have consequently led to alteration of macroinvertebrate taxonomic and functional community dissimilarity and affected the relative effects of environmental and spatial factors on beta diversity and its components. Our study helps understand the ecological processes associated with dam impacts on macroinvertebrate biodiversity and the conservation potential of undammed rivers. In addition, our results showed that taxonomic and functional beta diversities can provide complementary information about dam impacts on riverine biodiversity.

Butterfly Conservation in China: From Science to Action

About 10% of the Earth's butterfly species inhabit the highly diverse ecosystems of China. Important for the ecological, economic, and cultural services they provide, many butterfly species experience threats from land use shifts and climate change. China has recently adopted policies to protect the nation's biodiversity resources. This essay examines the current management of butterflies in China and suggests various easily implementable actions that could improve these conservation efforts. Our recommendations are based on the observations of a transdisciplinary group of entomologists and environmental policy specialists. Our analysis draws on other successful examples around the world that China may wish to consider. China needs to modify its scientific methodologies behind butterfly conservation management: revising the criteria for listing protected species, focusing on umbrella species for broader protection, identifying high priority areas and refugia for conservation, among others. Rural and urban land uses that provide heterogeneous habitats, as well as butterfly host and nectar plants, must be promoted. Butterfly ranching and farming may also provide opportunities for sustainable community development. Many possibilities exist for incorporating observations of citizen scientists into butterfly data collection at broad spatial and temporal scales. Our recommendations further the ten Priority Areas of China's National Biodiversity Conservation Strategy and Action Plan (2011-2030).

Macroinvertebrate Communities in a Lake of an Inter-Basin Water Transfer Project and Its Implications for Sustainable Management

In the present study, we choose the Weishan Lake, one of important water transfer and storage lakes on the eastern route of the South-to-North Water Diversion Project (SNWD) in China, to clarify how the community structure and assemblage-environment relationships of macroinvertebrates varied across three typical habitats (the River Mouth, Canal and Lake regions) over the four seasons in 2012. A total of 72 taxa belonging to 3 phyla, 9 classes and 24 families were recorded, with tolerant oligochaetes and chironomids as the dominant taxa. The environmental conditions and macroinvertebrate assemblages were clearly separated at spatial and temporal scales. Assemblage structure showed both significant but larger spatial than seasonal variations, with a clear separation of sites from three regions in an ordination plot. Compared to the temporal scale, more indicator species were retained to be responsible for the regional differences according to the two-way cluster analysis. Different environmental variables were significant for distinguishing macroinvertebrate assemblages among four seasons, and among them, pH was the only variable which was retained in all models. Our study provided useful background information of environmental characteristics and macroinvertebrate communities in a typical water transfer and storage lake before the water transfer of the SNWD. After the operation of SNWD, we envisage inter-basin water transfer (IBWT), which is usually accompanied by water level rise, nutrient pattern change and biota succession, will seriously affect recipient basins. Therefore, we propose several management strategies for SNWD: (1) target and detailed data should be collected on a timely basis; (2) government should prevent water pollution and adopt effective measures to protect the water environment; (3) the environmental assessments and other aspects of IBWT planning should be coordinated; (4) an overall consideration of different basins should be given to achieve a greater range of water resources planning, scheduling, and allocation; and (5) the migration and invasion of species should be of concern during the operation of the project.

Seasonal shifts in the assembly dynamics of benthic macroinvertebrate and diatom communities in a subtropical river

Identifying seasonal shifts in community assembly for multiple biological groups is important to help enhance our understanding of their ecological dynamics. However, such knowledge on lotic assemblages is still limited. In this study, we used biological traits and functional diversity indices in association with null model analyses to detect seasonal shifts in the community assembly mechanisms of lotic macroinvertebrates and diatoms in an unregulated subtropical river in China. We found that functional composition and functional diversity (FRic, FEve, FDis, MNN, and SDNN) showed seasonal variation for macroinvertebrate and diatom assemblages. Null models suggested that environmental filtering, competitive exclusion, and neutral process were all important community assembly mechanisms for both biological groups. However, environmental filtering had a stronger effect on spring macroinvertebrate assemblages than autumn assemblages, but the effect on diatom assemblages was the same in both seasons. Moreover, macroinvertebrate and diatom assemblages were shaped by different environmental factors. Macroinvertebrates were filtered mainly by substrate types, velocity, and CODMn, while diatoms were mainly shaped by altitude, substrate types, and water quality. Therefore, our study showed (a) that different biological assemblages in a river system presented similarities and differences in community assembly mechanisms, (b) that multiple processes play important roles in maintaining benthic community structure, and (c) that these patterns and underlying mechanisms are seasonally variable. Thus, we highlight the importance of exploring the community assembly mechanisms of multiple biological groups, especially in different seasons, as this is crucial to improve the understanding of river community changes and their responses to environmental degradation.