Forty one registrants from nineteen countries attended the Symposium. Twenty seven papers were presented during six sessions. These papers are published in the present volume some as abstracts only, ...except for one.
Wing polymorphism is reported for the first time in female specimens of Zwicknia bifrons from the River Esk, Cumbria. Identification of specimens is confirmed by morphological features and DNA ...sequencing.
Stoneflies are a globally threatened aquatic insect order. In Arkansas, a diverse group of winter stonefly (Capniidae: Allocapnia) have not been surveyed since the 1980s, likely because species-level ...identification requires the rarely-collected adult form. Allocapnia mohri, a regional endemic, was previously commonly found in mountainous, intermittent streams from the Ouachita Mountains ecoregion north to the Ozark Highlands, but no species distributional models including land use or climate variables exist to our knowledge. We collected adults from 71 stream reaches from the historic Arkansas range from November to April 2020 and 2021. We modeled distributions using random forest (RF) models populated with landscape, climate, and both data to determine which were most predictive of species presence. Correlations between landscape or climate variables and presence were examined using multiple logistic regression. The landscape RF models performed better than the climate or landscape + climate RF models. A. mohri presence sites tended to have a greater elevation, a lower mean July temperature, and a greater percentage of very slow infiltration soils in the watershed, compared to absence sites. A. mohri was absent at the Ouachita Mountains sites and may be experiencing a range contraction or migration northward.
Human activities may influence the diversity of aquatic insects in rivers. This study aims to assess the diversity of aquatic insects and their relation with mercury levels and water quality along ...rivers located near the gold mine in Poboya, Central Sulawesi. The insects were collected at six locations based on human activity levels. At each site, the mercury level of water was measured using atomic absorption spectrophotometry (AAS). In addition, water temperature, acidity, dissolved oxygen, and total dissolved solids were determined. The study recorded 23 species of aquatic insects belonging to 7 orders and 14 families. Mercury levels in the rivers did not exceed the threshold except at two sites and did not affect aquatic insects’ diversity. The diversity of aquatic insects, however, tends to decrease downstream. The diversity of aquatic insects, particularly the Ephemeroptera, Plecoptera, and Trichoptera orders, tended to be higher at the higher dissolved oxygen sites.
The effects of heavy metal pollution on benthic macroinvertebrate communities in tropical streams draining ultramafic systems have not been explored, despite a pressing need for ecological risk ...assessment to protect and manage aquatic ecosystems in these areas. The objective of this study was to examine benthic macroinvertebrate community composition in relation to metal concentrations in stream sediments and other physico-chemical variables in the Manyame River system, which drains part of the Great Dyke of Zimbabwe. Benthic macroinvertebrate sampling and community composition analysis, sediment collection, processing and metal analysis and assessment of other variables in the water column were done once at 55 sampling sites: 12 urban, 30 communal (i.e. sparsely populated rural areas, with livelihoods centred around subsistence agriculture) and 11 Great Dyke sites. Canonical correspondence analysis and partial canonical correspondence analysis (pCCA) were used to determine the importance of sediment heavy metal concentrations in explaining benthic macroinvertebrate community composition in comparison with other factors. Water quality ranged from very poor for urban locations due to sewage pollution, to good in communal locations. Significantly high concentrations of metals (ANOVA, p<0.05) and high magnesium/calcium (Mg/Ca) ratio were recorded in sediments for the Great Dyke site locations. The Mg/Ca ratio, Ca2+, Cr3+ and K+ were found to be important metals structuring benthic macroinvertebrate communities in the study streams, with metals explaining a larger percentage (58.0%) of the total variation explained compared to other variables (35.9%). However, taxa richness, diversity, evenness, percentage of Ephemeroptera, Plecoptera Trichoptera related metrics were higher at some Great Dyke sites than at communal sites. Thus, measures of taxa richness, diversity and %EPT may provide misleading information when assessing heavy metals in moderately polluted environments as in this study. Assessment of tropical streams draining ultramafic systems that are heavy metal-contaminated should also include benthic invertebrate community structure analysis, as it is possible that common endpoints, such as %EPT, may not identify impacts to aquatic communities.
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•Response of macroinvertebrate communities to sediment metal levels was investigated in tropical streams.•Mg/Ca ratio>Ca>DO>TP>TDS>Cr>K: in order of importance in determining macroinvertebrate communities•Relative variation explained: metals levels=58.0%; other variables=35.9%•Assessment of tropical metal-contaminated streams to focus more on macroinvertebrate community structure than on the EPT related metrics
Patches of riparian woody vegetation potentially help mitigate environmental impacts of agriculture and safeguard biodiversity. We investigated the effects of riparian forest on invertebrate ...diversity in coupled stream-riparian networks using a case study in the Zwalm river basin (Flanders, Belgium). Agriculture is one of the main pressures in the basin and riparian forest is limited to a number of isolated patches. Our 32 study sites comprised nine unshaded “unbuffered” sites which were paired with nine shaded “buffered” sites on the same stream reach, along with five ‘least-disturbed’ sites and nine downstream sites. We sampled water chemistry, habitat characteristics and stream and riparian invertebrates (carabid beetles and spiders) at each site. Three methods were used to quantify riparian attributes at different spatial scales: a visually-assessed qualitative index, quantitative estimates of habitat categories in six rectangular plots (10 × 5 m) and geographic information system (GIS)-derived land cover data. We investigated relationships between invertebrates and riparian attributes at different scales with linear regression and redundancy analyses. Spiders and carabids were most associated with local riparian attributes. In contrast, aquatic macroinvertebrates were strongly influenced by the extent of riparian vegetation in a riparian band upstream (100–300 m). These findings demonstrate the value of quantifying GIS-based metrics of riparian cover over larger spatial scales into assessments of the efficacy of riparian management as a complement to more detailed local scale riparian assessments in situ. Our findings highlight the value of even small patches of riparian vegetation in an otherwise extensively disturbed landscape in supporting biodiversity of both terrestrial and freshwater invertebrates and emphasize the need to consider multiple spatial scales in riparian management strategies which aim to mitigate human impacts on biodiversity in stream-riparian networks.
Summary
Stream invertebrate assemblages are structured by environmental factors acting at multiple spatial scales. Identifying the spatial scale that most influences the species–environment ...relationships is a major goal of community ecology.
We evaluated the importance of catchment and site scales and associated environmental variables in shaping Ephemeroptera, Plecoptera and Trichoptera (EPT) assemblages in Neotropical savanna headwater streams.
Sampling sites were associated with 20 catchment‐scale variables that depicted land cover and land use as well as natural geophysical variables such as altitude and climate. Site‐scale habitat was characterised by 55 variables that described habitat hydromorphology, substrate, flow, canopy, in‐stream cover and water quality. EPT traits were assessed using 28 categories of 7 biological traits, which represented the best available current knowledge for EPT in Neotropical savanna streams.
We analysed the relationships between the catchment‐ and site‐scale habitat variables and the taxonomic and trait composition of insect assemblages using 1,760 samples collected in 160 stream sites.
Catchment‐ and site‐scale variables both explained significant variation in EPT taxon and trait composition. Substrate, habitat hydromorphology and land use most influenced variation in taxonomic composition, whereas trait composition was mainly affected by land use. Catchment geographic position explained less assemblage variation.
To our knowledge, this study is the first assessment of the impact of catchment‐ and site‐scale variables on the trait and taxon composition of stream insect assemblages in Neotropical savanna streams. It highlights the need for better regional biological knowledge of invertebrates to generate more general trait‐based approaches in freshwater ecosystem conservation.
Spatial pattern comprehension, dynamism of energy, and transfer of matter in running freshwater systems are significant for the functional composition of aquatic communities. Recently, the ...trait-based approach has become the center of functional assessment. The trait-based approach can complement structural bioassessment tools and has the advantage of combining ecological features and biological characteristics rather than only the use of a taxonomic-based approach. In the current study, we explored the differential responses of EPT (Ephemeroptera, Plecoptera, and Trichoptera) traits in selected stream sites in the northwestern Rif of Morocco. A Surber sampler with a 500-µm mesh size and dimensions of 20 × 20 cm was used to collect EPT samples at the sites. Physicochemical and hydromorphological parameters, including temperature, pH, BOD
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, NO
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, Cl
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, depth, and current velocity, were used to characterize the water quality of the sampled sites. We used 54 trait modalities belonging to 11 trait classes to describe the collected EPT at the family level. We conducted RLQ model and fourth-corner test to examine the interaction between the EPT traits assemblage and habitat predictors at the 36 sampled sites along the stretch of the study area. The RLQ ordination revealed that the distribution patterns of EPT traits differed significantly over the 36 sites. Thus, we expected that the EPT traits assemblage would reflect the degree of the detected environmental pressures. The RLQ model indicated that elevated nutrient levels and conductivity were the key factors explaining most of the variability in functional traits at the downstream sampled sites. EPT traits such as life cycle duration, food preferences, maximal potential size, and substrate preference were positively associated with sites exhibiting notable deterioration. Baetidae and Leptophlebidae in S2, S3, and S20 favored these trait assemblages. The fourth-corner test revealed that there was no statistically significant difference in the relationship between the EPT traits and selected physicochemical and hydromorphological parameters.
We recorded a total of nine species and four subspecies of stoneflies from eleven localities in the Sarnena Sredna Gora Mountains (Bulgaria). They belong to six families and eight genera of the order ...Plecoptera and represent 11.93% of the 109 stoneflies known up to now for Bulgaria. One of the registered species is endemic, while ten stoneflies have been found for the first time from the mountains.
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