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

Taxonomic and functional traits of macroinvertebrate community along fish farming pollution gradient: Taxonomic sufficiency for reliable bioassessment

The expansion of fish farming globally, driven by rising demand for fish as a food source, has raised substantial environmental concerns due to its impact on aquatic ecosystems. This study investigates the effects of fish farming effluents on taxonomic and functional diversity of macroinvertebrate community and test how taxonomic resolution impacts their effectiveness as pollution indicators. Macroinvertebrate samples were collected from seven trout farms, with sampling sites categorized based on proximity to farm effluents. Results indicate that fish farming effluents significantly alter macroinvertebrate communities, with observable changes in both taxonomic and functional metrics. Although traditional taxonomic metrics revealed differences along the pollution gradient, functional diversity measures provided more sensitive indicators of ecological changes. Functional traits, even at coarse taxonomic resolutions, better reflected shifts in ecological processes than taxonomic diversity alone. The study supports integrating both taxonomic and functional diversity measures in river restoration and management practices to optimize pollution detection and ecological assessment. Combining taxonomic and functional approaches in bioassessment is recommended for better evaluation of water quality and ecosystem health. Functional attributes can simplify routine monitoring, especially for poorly known macroinvertebrate taxa. Nevertheless, metrics related to chironomids showed significant changes along the pollution gradient and were useful for detecting fish farm effluents. Chironomid data at both fine and coarse taxonomic levels revealed the impact of pollution effectively.

Mt. Apo Biotic Index (MABI): a macroinvertebrate-based multimetric index for assessing stream biotic integrity of wadeable streams within a geothermal production field in Mindanao, Philippines

Monitoring the ecological integrity of streams is a challenge, especially in the tropics, which experience high rates of degradation. Multimetric scoring systems have been widely used in other countries in evaluating current stream conditions; however, it has never been done in the Philippines. This study focuses on the development of a benthic macroinvertebrate-based multimetric index for the overall assessment of streams in Mt. Apo, Mindanao, Philippines. The index was used to develop existing physicochemical and biological data obtained during 2010 to 2015 surveys from 15 monitoring sites within the Mt. Apo Geothermal Project (MAGP). Metrics related to benthic macroinvertebrate abundance, richness, composition, functional habit groups, functional feeding groups, and pollution tolerance were screened for their range, temporal stability, sensitivity, discrimination efficiency (DE), redundancy, and responsiveness to anthropogenic impacts. The resulting multimetric index, the Mt. Apo Biotic Index (MABI), is computed as the sum of the individual metric scores after metric transformation using the discrete scoring method DRQ1 (D = discrete, R = reference, Q1 = 25th percentile) of the six core metrics: (1) number of Coleoptera individuals (abundance), (2) number of taxa (richness); (3) [%] Coleoptera taxa (composition), (4) number of sprawler individuals (functional habit group), (5) [%] collector-filterer taxa (functional feeding group), and (6) the Biological Monitoring Working Party Thai version (BMWP-Thai; pollution tolerance). MABI scores were classified into five condition ratings of stream biotic integrity: very poor (6 to 10), poor (11 to 15), fair (16 to 20), good (21 to 25), and excellent (26 to 30). The study demonstrated that the resulting pilot index may provide useful information that will benefit policymakers and resource managers in formulating more comprehensive stream management approaches and conservation plans for priority sites in the region.

The impact of land use on stream macroinvertebrates: a bibliometric analysis for 2010-2021

Changes in stream biodiversity are now mainly driven by land-use development. However, a literature review on the impact of land use on stream macroinvertebrates is lacking, especially a scientometric review. Here, we bibliometrically analyzed the literature on land use and stream macroinvertebrates that were published in 2010-2021 and listed in the Web of Science database. We found that the impact of land use on stream macroinvertebrates had been increasingly studied and that these studies were distributed across the globe and had multi-national collaborations. Through co-citation analysis and high-frequency keyword analysis, we found that land use and some environmental factors, especially water quality and habitat, affected macroinvertebrate community biodiversity, biotic integrity, and patterns. Macroinvertebrate traits, analytical methods or models, evaluation index development, and riparian vegetation were the research hotspots. Using historical direct citation network analysis, we also found that the analytical methods in this field and the macroinvertebrate evaluation index had clear development trends from 2010 to 2021. Our findings can help researchers quickly grasp the background of the impact of land use on stream macroinvertebrates and inform future research.

Non-interactive effects drive multiple stressor impacts on the taxonomic and functional diversity of atlantic stream macroinvertebrates

Freshwaters are considered among the most endangered ecosystems globally due to multiple stressors, which coincide in time and space. These local stressors typically result from land-use intensification or hydroclimatic alterations, among others. Despite recent advances on multiple stressor effects, current knowledge is still limited to manipulative approaches minimizing biological and abiotic variability. Thus, the assessment of multiple stressor effects in real-world ecosystems is required. Using an extensive survey of 50 stream reaches across North Portugal, we evaluated taxonomic and functional macroinvertebrate responses to multiple stressors, including marked gradients of nutrient enrichment, flow reduction, riparian vegetation structure, thermal stress and dissolved oxygen depletion. We analyzed multiple stressor effects on two taxonomic (taxon richness, Shannon-diversity) and two trait-based diversity indices (functional richness, functional dispersion), as well as changes in trait composition. We found that multiple stressors had additive effects on all diversity metrics, with nutrient enrichment identified as the most important stressor in three out of four metrics, followed by dissolved oxygen depletion and thermal stress. Taxon richness, Shannon-diversity and functional richness responded similarly, whereas functional dispersion was driven by changes in flow velocity and thermal stress. Functional trait composition changed along a major stress gradient determined by nutrient enrichment and oxygen depletion, which was positively correlated with organisms possessing fast-living strategies, aerial respiration, adult phases, and gathering-collector feeding habits. Overall, our results reinforce the need to consider complementary facets of biodiversity to better identify assembly processes in response to multiple stressors. Our data suggest that stressor interactions may be less frequent in real-word streams than predicted by manipulative experiments, which can facilitate mitigation strategies. By combining an extensive field survey with an integrative consideration of multiple biodiversity facets, our study provides new insights that can help to better assess and manage rivers in a global change context.

Soil Moisture and Available Phosphorus as the Factors Driving Variation in Functional Characteristics across Different Restoration Communities in a Subtropical Mountain Ecosystem

Functional characteristics are increasingly used to evaluate the success of different vegetation restoration. Community functional diversity (FD) and the community-weighted mean (CWM), as two main complementary components, are closely linked to site environment and ecosystem functions. However, the patterns and driving factors of functional characteristics are still not clear in different vegetation restoration types. Here, four community restoration types (secondary shrubland, SL; Pinus yunnanensis forest, PF; mixed needle–broad-leaved forest, MF; natural secondary forest, NSF) were selected to investigate species diversity, FD, CWM, and soil physicochemical properties. The relative effects of species diversity and soil abiotic features on variation in functional characteristics were then evaluated. We found that different restoration communities altered most community structures and functional properties in terms of species diversity, FD, and CWM. CWM values and FD in different communities presented different distribution patterns depending on certain traits and parameters. Significant correlations between functional traits were found at the species and community scales, suggesting a potential covariation between these selected traits in communities. The results of redundancy analysis and variation partitioning showed that most of the variation in functional characteristics, especially CWM, was explained by soil moisture and available phosphorus, indicating that habitat filters regulate the functional characteristics of plant communities mainly by changing the dominant species composition and functional traits of species. Therefore, the selection of restoration species adapted to low soil moisture and available phosphorus and the construction of communities based on selected species as the dominant species can effectively drive community assembly and ecosystem functions in the vegetation restoration process.

Responses of macroinvertebrate functional trait structure to river damming: From within-river to basin-scale patterns

Revealing how aquatic organisms respond to dam impacts is essential for river biomonitoring and management. Traditional examinations of dam impacts on macroinvertebrate assemblages were frequently conducted within single rivers (i.e., between upstream vs. downstream locations) and based on taxonomic identities but have rarely been expanded to level of entire basins (i.e., between dammed vs. undammed rivers) and from a functional trait perspective. Here, we evaluated the effects of dams on macroinvertebrate assemblages at both the within-river and basin scales using functional traits in two comparable tropical tributaries of the Lancang-Mekong River. At different scales, maximum body size, functional feeding groups (FFG), voltinism and occurrence in drift respond significantly to dam impact. Armoring categories varied significantly between downstream sites and upstream sites, and oviposition behavior, habits and adult life span significantly differed between rivers. The key traits at the within-river scale resembled to those at the between-river scale, suggesting that within-river trait variation could further shape functional trait structure at the basin scale in dammed rivers. Furthermore, water nutrients and habitat quality induced by dams showed the most important role in shaping trait structure, although trait-environment relationships varied between the two different scales. In addition, the trait-environment relationships were stronger in the dry season than in the wet season, suggesting a more important role of environmental filtering processes in the dry season compared with the wet season. This study highlights the utility of the trait-based approach to diagnose the effects of damming and emphasizes the importance of spatial scale to examine dam impacts in riverine systems.