The efficacy of DNA barcoding in the classification,genetic differentiation,and biodiversity assessment of benthic macroinvertebrates

Macroinvertebrates have been recognized as key ecological indicators of aquatic environment and are the most commonly used approaches for water quality assessment. However, species identification of macroinvertebrates (especially of aquatic insects) proves to be very difficult due to the lack of taxonomic expertise in some regions and can become time‐consuming. In this study, we evaluated the feasibility of DNA barcoding for the classification of benthic macroinvertebrates and investigated the genetic differentiation in seven orders (Insecta: Ephemeroptera, Plecoptera, Trichoptera, Diptera, Hemiptera, Coleoptera, and Odonata) from four large transboundary rivers of northwest China and further explored its potential application to biodiversity assessment. A total of 1,144 COI sequences, belonging to 176 species, 112 genera, and 53 families were obtained and analyzed. The barcoding gap analysis showed that COI gene fragment yielded significant intra‐ and interspecific divergences and obvious barcoding gaps. NJ phylogenetic trees showed that all species group into monophyletic species clusters whether from the same population or not, except two species (Polypedilum. laetum and Polypedilum. bullum). The distance‐based (ABGD) and tree‐based (PTP and MPTP) methods were utilized for grouping specimens into Operational Taxonomic Units (OTUs) and delimiting species. The ABGD, PTP, and MPTP analysis were divided into 177 (p = .0599), 197, and 195 OTUs, respectively. The BIN analysis generated 186 different BINs. Overall, our study showed that DNA barcoding offers an effective framework for macroinvertebrate species identification and sheds new light on the biodiversity assessment of local macroinvertebrates. Also, the construction of DNA barcode reference library of benthic macroinvertebrates in Eurasian transboundary rivers provides a solid backup for bioassessment studies of freshwater habitats using modern high‐throughput technologies in the near future.     

Can artificial ecological islands alter the biodiversity of macroinvertebrate? A case study in Fujin National Wetland Park,the Sanjiang Plain,China

1. Many policies and studies globally have highlighted the pivotal role of wetland ecosystems regarding wetland biota and their ecological status. With the strengthening of wetland ecosystem management legislation and policy, wetland restoration should also consider increasing habitat diversity to improve biota. We explore whether the construction of artificial ecological islands can increase the diversity of and macroinvertebrates before assessing the effects of actively constructing islands via human intervention on wetland protection.
2. We discuss changes in macroinvertebrate diversity (i) with and without islands, (ii) at different water‐level gradients surrounding the islands, (ⅲ) on different island substrates, and (ⅳ) at different time scales. We used ANOVA, ANOSIM, and cluster analysis to test the differences.
3. The macroinvertebrate communities had spatially heterogeneous distributions which changes over time due to both natural and anthropogenic stresses. The establishment of islands significantly increased the community composition and biodiversity of the macroinvertebrate. Water depth and substrate affect community composition of macrozoobenthos. The abundance and diversity of macroinvertebrates can influence the biodiversity of their predators (fish and waterbirds). Potentially, the construction of islands could provide some cobenefits for the conservation of wetland fauna.

Synthesis and applications. Establishing artificial ecological islands in broad open‐water areas and increasing water‐level gradient and substrate diversity can increase microhabitat availability and habitat heterogeneity. These changes can adapt to different ecological niches of aquatic organisms, increase biodiversity, and have a positive effect on the ecological restoration of inland freshwater marshes and wetlands.     

Hotspots of biodiversity or homogeneous landscapes? Farm dams as biodiversity reserves in Australia

In many countries the ubiquitous farm dam or pond is an integral component of agricultural landscapes. In Australia there are in excess of half a million farm ponds, used largely for irrigation or for watering stock. In contrast to Europe, these wetlands are being decommissioned in response to the introduction of government policy that regulates water usage from these dams. They are also being in-filled with expanding urbanisation without consideration of their benefits as reservoirs of biodiversity. We compared the diversity of macroinvertebrates in farm dams with nearby stream habitats on a cool temperate tableland in central New South Wales. There was greater diversity in-stream than in the dams; however, dam sites showed a larger mean diversity and total diversity per site than in-stream. Species recorded in-stream were more frequently represented by single individuals while species were recorded more consistently in dams. We also observed that macroinvertebrate assemblages were more similar to those in the same dam in different seasons than to adjacent dams in the same season. Some species recorded had not previously been recorded from farm dams. In contrast to the general consensus that Australian farm dams are homogeneous environments with a range of common widespread species, we showed that they provide a variety of sustainable reservoirs of biodiversity within the landscape. They also have the potential to provide ‘stepping stones’ between undisturbed and modified habitats, in part countering the fragmentation that occurs as a result of agricultural practices.     

The effects of bankside management on chalk stream invertebrate communities

SUMMARY 1. Communities of aquatic macroinvertebrates and the terrestrial adult phases of aquatic insects were investigated from short stretches of English chalk streams with two different bankside vegetation types: simply structured grazed grass (grazed) and structurally complex herbaceous vegetation with scattered trees (ungrazed). Macroinvertebrates were sampled in spring, summer, autumn and winter 1996–97 from three aquatic habitats: mid-channel gravel, patches of the aquatic macrophyte Ranunculus and marginal emergent macrophytes. The terrestrial adult phases of aquatic insects were sampled in spring, summer and autumn from bankside vegetation.
2. Total macroinvertebrate abundance did not differ between stretches with different bankside vegetation. Taxon richness of mid-channel gravel was, however, significantly higher in ungrazed compared with grazed stretches and Shannon diversity ( H ') of mid-channel gravel and marginal vegetation was significantly higher in ungrazed compared with grazed stretches. Total abundance, taxon richness and Shannon diversity ( H ') of the terrestrial adult phases of aquatic insect were significantly higher from the bankside vegetation of ungrazed compared with grazed stretches.
3. Ordination of communities of aquatic macroinvertebrates and terrestrial adults demonstrated that individual families of both groups were generally more abundant in ungrazed stretches. Many more families were significantly associated with ungrazed stretches than with grazed stretches.
4. This investigation has shown that high structural diversity of bankside vegetation along lowland chalk streams is accompanied at the reach scale by increased diversity of both aquatic macroinvertebrates and the terrestrial adult phases of aquatic insects. The conservation potential of such streams may thus be lowered by management practices that result in the removal or simplification of bankside vegetation along extensive stream stretches.     

Response of benthic macroinvertebrates to whole-lake, non-native fish treatments in mid-elevation lakes of the Trinity Alps, California

Introduced fish reduce the abundance and diversity of native aquatic fauna, but the effect can be reduced in complex habitats. We manipulated fish populations in forested mountain lakes to determine whether or not fish affected benthic macroinvertebrate composition across lakes with differing habitat complexity. We compared abundance, biomass, body-length, and community structure of benthic macroinvertebrates from 16 lakes with three treatments (fish stocked, suspended stocking, fish removed) and unstocked fishless “controls”. Over 4 years, we assessed the relative importance of fish and environmental variables influencing the composition of benthic macroinvertebrates. Control lakes had the greatest overall abundance of macroinvertebrates when chironomid midges were excluded. Abundances of insects in the clinger/swimmer functional group and caddisflies were greatest in the control lakes but were primarily influenced by habitat variables including the availability of aquatic vegetation and wood. Total biomass and mean body length of macroinvertebrates were not affected by treatment. Taxon richness of macroinvertebrates was about 40% greater in the control lakes compared to the treatment lakes but did not differ among treatments. Our results suggest that fish reduce susceptible macroinvertebrate richness and abundances, but that changes associated with alterations of fish composition are confounded by other factors in complex lake habitats.     

Impact of a dam on benthic macroinvertebrates in a small river in a biodiversity hotspot: Cape Floristic Region, South Africa

Suitable reservoirs and monitoring methods are needed to manage scarce water supplies in dry countries. We assessed here the impact on aquatic macroinvertebrates of the only dam on the Eerste River, which runs through the heart of a biodiversity hotspot, the Cape Floristic Region, South Africa. The dam and associated activities, were the only forms of disturbance in this otherwise pristine area. We sampled over 20,000 macroinvertebrate individuals and illustrated some categorical effects of the impoundment and its effects on macroinvertebrate assemblages. Macroinvertebrate species diversity below the dam was only half of that in the pristine catchment area above the dam. Furthermore, Ephemeroptera, Plecoptera and Trichoptera diversity and abundance dropped to almost zero as a result of the impoundment. In contrast, the abundance of the Diptera family Chironomidae increased substantially below the dam. These changes in macroinvertebrate diversity mirrored those recorded in biologically less diverse areas, but are of major concern in this biodiversity hotspot with its rich endemic fauna. We conclude that such an impoundment, while important for human welfare, results in a high price being paid in terms of loss of local biodiversity.     

Water hyacinth,Eichhornia crassipes (Pontederiaceae), reduces benthic macroinvertebrate diversity in a protected subtropical lake in South Africa

The socio-economic impacts of the free-floating aquatic plant water hyacinth, Eichhornia crassipes (Pontederiaceae), on aquatic systems are well documented, yet the impacts on aquatic biodiversity, particularly invertebrate biodiversity, are less well understood. This study aimed to determine whether the presence of water hyacinth altered the diversity and assemblage structure of benthic macroinvertebrates in a conservation area. The benthic macroinvertebrate assemblage was sampled over 1 year at five sites under water hyacinth mats and at five sites without water hyacinth at Lake Nsezi—Nseleni River in the vicinity of Richards Bay, KwaZulu-Natal, South Africa. Artificial substrates were placed beneath water hyacinth mats or in the open water to allow for colonization by freshwater macroinvertebrates, and left for a period of 6 weeks, repeated on seven occasions. Twenty nine families comprising 18,797 individuals were collected, 817 (13 families) individuals were from under water hyacinth mat sites compared to 17,980 (27 families) individuals from open water sites. Ninety-eight percent of individuals collected were, however, the invasive snail, Tarebia granifera. Open water samples were separated from samples beneath the water hyacinth mat by non-metric Multidimensional Scaling, indicating reduced biodiversity associated with the presence of water hyacinth. Exclusion of the dominant Thiaridae from the analysis did not alter the groupings. Family richness(s) and abundance (N) were significantly higher in open water communities(S: H₃ = 21.09; P = 0.0001; N: H₃ = 22.58; P = 0.00001), while evenness (J’) was higher under water hyacinth mats (H₃ = 20.13; P = 0.0002). The presence of water hyacinth had a significantly negative impact on aquatic macroinvertebrate biodiversity in a conservation area, and therefore the control of this invasive aquatic plant must play a major role in catchment management.     

A comparison of the catchment sizes of rivers,streams, ponds,ditches and lakes: implications for protecting aquatic biodiversity in an agricultural landscape

In this study we compared the biodiversity of five waterbody types (ditches, lakes, ponds, rivers and streams) within an agricultural study area in lowland England to assess their relative contribution to the plant and macroinvertebrate species richness and rarity of the region. We used a Geographical Information System (GIS) to compare the catchment areas and landuse composition for each of these waterbody types to assess the feasibility of deintensifying land to levels identified in the literature as acceptable for aquatic biota. Ponds supported the highest number of species and had the highest index of species rarity across the study area. Catchment areas associated with the different waterbody types differed significantly, with rivers having the largest average catchment sizes and ponds the smallest. The important contribution made to regional aquatic biodiversity by small waterbodies and in particular ponds, combined with their characteristically small catchment areas, means that they are amongst the most valuable, and potentially amongst the easiest, of waterbody types to protect. Given the limited area of land that may be available for the protection of aquatic biodiversity in agricultural landscapes, the deintensification of such small catchments (which can be termed microcatchments) could be an important addition to the measures used to protect aquatic biodiversity, enabling ‘pockets’ of high aquatic biodiversity to occur within working agricultural landscapes. Guest editors: R. Céréghino, J. Biggs, B. Oertli & S. Declerck The ecology of European ponds: defining the characteristics of a neglected freshwater habitat     

Rainbow Trout diets and macroinvertebrates assemblages responses from watersheds dominated by native and exotic plantations

Over the past few decades, land-use changes through conversion of global forest cover to exotic plantations is contributing to both habitat and biodiversity loss and species extinctions. To better understand human influences on ecosystem, we use diet composition from introduced Rainbow Trout Oncorhynchus mykiss as indicator of potential changes in the composition of stream-macroinvertebrates due to land use changes from native to exotic vegetation (eucalyptus plantations) in southern Chile. Water quality variables, aquatic macroinvertebrates and Rainbow Trout diet were studied in 12 sites from mountain streams located in two watersheds including one dominated by native riparian vegetation and the other dominated by exotic vegetation. As expected, richness and abundance of macroinvertebrates were clearly higher at sites in native forest than in those with exotic vegetation. Collector-gatherer was the most abundant functional feeding group, but there was no statistical difference in the functional composition between the two watersheds. Differences in in-stream macroinvertebrate availability was more higher correlated with changes in Rainbow Trout diets. Specifically, taxa consumed from the watershed dominated by native forests was higher than from the watershed with exotic vegetation. Additional environmental variables showed statistical differences between watersheds. The exotic vegetation sites had the highest concentrations of dissolved solids, suspended solids, nitrates, chlorides and sulphates. Our findings show that macroinvertebrate assemblage structure and trout diets can be altered by changes in riparian vegetation. The absence of specific macroinvertebrate taxa in streams with exotic vegetation was captured by the composition of trout diets. This suggest that Rainbow Trout diets can be a good biological indicator of land use practices and thus, diet can be used as a rapid and effective tool for evaluate environmental quality. Our findings provide insights about the design of aquatic monitoring programmes to improve detection of anthropogenic impacts in streams in South America and elsewhere.     

Pond Acoustic Sampling Scheme: A draft protocol for rapid acoustic data collection in small waterbodies

1. Freshwater conservation is vital to the maintenance of global biodiversity. Ponds are a critical, yet often under‐recognized, part of this, contributing to overall ecosystem functioning and diversity. They provide habitats for a range of aquatic, terrestrial, and amphibious life, often including rare and declining species.
2. Effective, rapid, and accessible survey methods are needed to enable evidence‐based conservation action, but freshwater taxa are often viewed as “difficult”—and few specialist surveyors are available. Datasets on ponds are therefore limited in their spatiotemporal coverage.
3. With the advent of new recording technologies, acoustic survey methods are becoming increasingly available to researchers, citizen scientists, and conservation practitioners. They can be an effective and noninvasive approach for gathering data on target species, assemblages, and environmental variables. However, freshwater applications are lagging behind those in terrestrial and marine spheres, and as an emergent method, research studies have employed a multitude of different sampling protocols.
4. We propose the Pond Acoustic Sampling Scheme (PASS), a simple protocol to allow a standardized minimal sample to be collected rapidly from small waterbodies, alongside environmental and methodological metadata. This sampling scheme can be incorporated into a variety of survey designs and is intended to allow access to a wide range of participants, without requiring complicated or prohibitively expensive equipment.
5. Adoption of this sampling protocol would enable consistent sound recordings to be gathered by researchers and conservation organizations, and allow the development of landscape‐scale surveys, data sharing, and collaboration within an expanding freshwater ecoacoustic community—rather than individual approaches that produce incompatible datasets. The compilation of standardized data would improve the prospects for effective research into the soundscapes of small waterbodies and aid freshwater conservation efforts.

     

The effectiveness of aquatic plants as surrogates for wider biodiversity in standing fresh waters

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The effects of taxonomy,diet, and ecology on the microbiota of riverine macroinvertebrates

Freshwater macroinvertebrates play key ecological roles in riverine food webs, such as the transfer of nutrients to consumers and decomposition of organic matter. Although local habitat quality drives macroinvertebrate diversity and abundance, little is known about their microbiota. In most animals, the microbiota provides benefits, such as increasing the rate at which nutrients are metabolized, facilitating immune system development, and defending against pathogenic attack. Our objectives were to identify the bacteria within aquatic invertebrates and determine whether their composition varied with taxonomy, habitat, diet, and time of sample collection. In 2016 and 2017, we collected 264 aquatic invertebrates from the mainstem Saint John (Wolastoq) River in New Brunswick, Canada, representing 15 orders. We then amplified the V3‐V4 hypervariable region of the 16S rRNA gene within each individual, which revealed nearly 20,000 bacterial operational taxonomic units (OTUs). The microbiota across all aquatic invertebrates were dominated by Proteobacteria (69.25% of the total sequence reads), but they differed significantly in beta diversity, both among host invertebrate taxa (genus‐, family‐, and order‐levels) and temporally. In contrast to previous work, we observed no microbiota differences among functional feeding groups or traditional feeding habits, and neither water velocity nor microhabitat type structured microbiota variability. Our findings suggest that host invertebrate taxonomy was the most important factor in modulating the composition of the microbiota, likely through a combination of vertical and horizontal bacterial transmission, and evolutionary processes. This is one of the most comprehensive studies of freshwater invertebrate microbiota to date, and it underscores the need for future studies of invertebrate microbiota evolution and linkages to environmental bacteria and physico‐chemical conditions.     

Influence of environmental variables on macroinvertebrate community structure in Lianhuan Lake

The structural characteristics of the macroinvertebrate community can effectively reflect the health status of lake ecosystems and the quality of the lake ecological environment. It is therefore important to identify the limiting factors of macroinvertebrate community structure for the maintenance of lake ecosystem health. In this study, the community composition of macroinvertebrate assemblages and their relationships with environmental variables were investigated in 13 small lakes within Lianhuan Lake in northern China. A self‐organizing map and K‐means clustering analysis grouped the macroinvertebrate communities into five groups, and the indicator species reflected the environmental characteristics of each group. Principal component analysis indicated that the classification of the macroinvertebrate communities was affected by environmental variables. The Kruskal–Wallis test results showed that environmental variables (pH, total phosphorus, nitrate, water temperature, dissolved oxygen, conductivity, permanganate index, and ammonium) had a significant effect on the classification of the macroinvertebrate communities. Redundancy analysis showed that mollusks were significantly negatively correlated with pH and chlorophyll a, while annelids and aquatic insects were significantly positively correlated with chlorophyll a and dissolved oxygen. Spearman correlation analysis showed that the species richness and Shannon''s diversity of macroinvertebrates were significantly negatively correlated with total phosphorus, while the biomass of macroinvertebrates was significantly negatively correlated with pH. High alkalinity and lake eutrophication have a serious impact on the macroinvertebrate community. Human disturbances, such as industrial and agricultural runoff, negatively impact the ecological environment and affect macroinvertebrate community structure. Thus, macroinvertebrate community structure should be improved by enhancing the ecological environment and controlling environmental pollution at a watershed scale.     

Ecological responses of aquatic macrophytes and benthic macroinvertebrates to dams in the Henares River Basin (Central Spain)

The ecological responses of aquatic macrophytes and benthic macroinvertebrates to deep-release dams in three impounded rivers of the Henares River Basin (Central Spain) were studied, specially focusing on the effects of nutrient enrichment caused by deep releases on these two freshwater communities. Three sampling sites, one upstream and two downstream from the reservoir, were established in each impounded river. Sampling surveys to collect submersed macrophytes and benthic macroinvertebrates at each sampling site were carried out in spring–summer of 2009 and 2011. Water temperature tended to decrease downstream from dams, whereas nitrate and phosphate concentrations tended to increase. These abiotic changes, particularly the downstream nutrient enrichment, apparently affected the macrophyte and macroinvertebrate communities. In the case of submersed macrophytes, total coverage and taxa richness increased downstream from dams. In the case of benthic macroinvertebrates, total density and total biomass also increased downstream, but taxa richness tended to decrease. Scrapers appeared to be the macroinvertebrate feeding group most favored downstream from dams as a probable consequence of the positive effect of nutrient enrichment on periphyton and perilithon abundance. Nutrients would ultimately come from water runoff over agricultural lands and over semi-natural forests and pastures, being subsequently accumulated in the hypolimnion of reservoirs.     

Community composition and distribution of macroinvertebrates in the Umzimvubu River,South Africa: a pre-impoundment study

This paper presents baseline biological data on aquatic macroinvertebrates and water quality in the Umzimvubu River and selected tributaries, Eastern Cape Province, South Africa, prior to the construction of proposed large-scale water resource developments. Sampling was conducted seasonally at 14 sites between 1996 and 1998. The macroinvertebrate community composition was strikingly similar (±70%) across sites. Faunal diversity was low (104 taxa in total), but many taxa found were sensitive to water quality change (ASPT 5.0 to 9.6), indicating good water quality, which is attributed to the currently undeveloped nature of the catchment. Concentrations of water quality variables fell within a narrow range, except for total suspended solids, which at times was very high (up to 8 532mg l^–1). The highly variable concentration of the total suspended solids and its potential effects on biodiversity need to be investigated further. It is likely that bilharzia will spread and that pest blackflies may become a problem to livestock if the water resources become developed as is proposed. We suggest that more flow gauging weirs are needed to measure flows better for future management and also that the implications of the proposed developments on the estuary need to be investigated.     

River Ecosystem Response to Prescribed Vegetation Burning on Blanket peatland

Catchment-scale land-use change is recognised as a major threat to aquatic biodiversity and ecosystem functioning globally. In the UK uplands rotational vegetation burning is practised widely to boost production of recreational game birds, and while some recent studies have suggested burning can alter river water quality there has been minimal attention paid to effects on aquatic biota. We studied ten rivers across the north of England between March 2010 and October 2011, five of which drained burned catchments and five from unburned catchments. There were significant effects of burning, season and their interaction on river macroinvertebrate communities, with rivers draining burned catchments having significantly lower taxonomic richness and Simpson’s diversity. ANOSIM revealed a significant effect of burning on macroinvertebrate community composition, with typically reduced Ephemeroptera abundance and diversity and greater abundance of Chironomidae and Nemouridae. Grazer and collector-gatherer feeding groups were also significantly less abundant in rivers draining burned catchments. These biotic changes were associated with lower pH and higher Si, Mn, Fe and Al in burned systems. Vegetation burning on peatland therefore has effects beyond the terrestrial part of the system where the management intervention is being practiced. Similar responses of river macroinvertebrate communities have been observed in peatlands disturbed by forestry activity across northern Europe. Finally we found river ecosystem changes similar to those observed in studies of wild and prescribed forest fires across North America and South Africa, illustrating some potentially generic effects of fire on aquatic ecosystems.     

Resource requirements for ecosystem conservation: A combined industrial and natural ecology approach to quantifying natural capital use in nature

Socioeconomic demand for natural capital is causing catastrophic losses of biodiversity and ecosystem functionality, most notably in regions where socioeconomic‐and eco‐systems compete for natural capital, e.g., energy (animal or plant matter). However, a poor quantitative understanding of what natural capital is needed to support biodiversity in ecosystems, while at the same time satisfy human development needs—those associated with human development within socioeconomic systems—undermines our ability to sustainably manage global stocks of natural capital. Here we describe a novel concept and accompanying methodology (relating the adult body mass of terrestrial species to their requirements for land area, water, and energy) to quantify the natural capital needed to support terrestrial species within ecosystems, analogous to how natural capital use by humans is quantified in a socioeconomic context. We apply this methodology to quantify the amount of natural capital needed to support species observed using a specific surveyed site in Scotland. We find that the site can support a larger assemblage of species than those observed using the site; a primary aim of the rewilding project taking place there. This method conceptualises, for the first time, a comprehensive “dual‐system” approach: modelling natural capital use in socioeconomic‐and eco‐systems simultaneously. It can facilitate the management of natural capital at the global scale, and in both the conservation and creation (e.g., rewilding) of biodiversity within managed ecosystems, representing an advancement in determining what socioeconomic trade‐offs are needed to achieve contemporary conservation targets alongside ongoing human development.     

Short‐term effects of low intensity fire on soil macroinvertebrate assemblages in different vegetation patch types in an Australian tropical savanna

Abstract Early dry season fires are a common land management regime employed across the tropical savannas of northern Australia. The rationale is that this reduces fuel loads and so reduces fire risk in the latter part of the dry season. Despite the acceptance of fire as a major management tool the ecological effects of fire remain uncertain. Vegetation patches and their associated macroinvertebrates play a critical role in the capture and recycling of water and nutrients. The aim of this study was to examine the responses of soil macroinvertebrates, within different types of vegetation patches, to early dry season fires in tropical savanna woodland in northern Australia. The abundance of major macroinvertebrate taxa and functional groups, and taxon richness were quantified in three vegetation patch types 2 weeks before and 2 weeks after burning. Termites dominated the soil macroinvertebrate assemblage sampled. Fire led to significant decreases in ant and spider abundances and overall taxon richness. Functional group analyses showed significant overall declines in the abundances of macropredators and litter transformers. There were also interactions between fire and patch type; in tree patches, fire significantly reduced total macroinvertebrate abundance, as well as the abundance of termites and ecosystem engineers. These changes in soil macroinvertebrates will potentially influence patch functionality, with important implications for soil processes and landscape health.     

Recovery of benthic macroinvertebrate and adult dragonfly assemblages in response to large scale removal of riparian invasive alien trees

Invasive alien organisms can impact adversely on indigenous biodiversity, while riparian invasive alien trees (IATs), through shading of the habitat, can be a key threat to stream invertebrates. We ask here whether stream fauna can recover when the key threat of riparian IATs is removed. Specifically, we address whether IAT invasion, and subsequent IAT removal, changes benthic macroinvertebrate and adult dragonfly assemblages, for the worse or for the better respectively. Natural riparian zones were controls. There were statistically significant differences between stream reaches with natural, IAT-infested and IAT-cleared riparian vegetation types, based on several metrics: immature macroinvertebrate taxon richness, average score per macroinvertebrate taxon (ASPT), a macroinvertebrate subset (Ephemeroptera, Plecoptera, Trichoptera and Odonata larvae; EPTO), and adult dragonfly species richness. Reaches with natural vegetation, or cleared of IATs, supported greater relative diversity of macroinvertebrates than reaches shaded by dense IATs. Greatest macroinvertebrate ASPT and EPTO were in reaches bordered by natural vegetation and those bordered by vegetation cleared of IATs, and the lowest where the riparian corridor was IATs. Highest number of adult dragonflies species was along streams cleared of dense IATs. Overall, results showed that removal of a highly invasive, dense canopy of alien trees enables recovery of aquatic biodiversity. As benthic macroinvertebrate scores and adult dragonfly species richness are correlated and additive, their combined use is recommended for river condition assessments.     

Setting Goals and Measuring Success: Linking Patterns and Processes in Stream Restoration

The influences of productivity, vegetation coverage, and benthivorous fish abundance on macroinvertebrate abundance and mean size were examined in Midwestern USA impoundments. While impoundment productivity was not strongly related to total abundance and mean size of macroinvertebrates, it was related to specific taxa. As productivity increased, Ephemeroptera and Odonata abundance decreased and Diptera abundance increased. Despite the shift in taxonomic composition, mean individual size of the macroinvertebrate community varied little with changes in impoundment productivity. Relationships between macroinvertebrates and benthivorous fish were mixed. Macroinvertebrate abundance, especially Diptera, increased with increases in bluegill Lepomis macrochirus Rafinesque abundance and decreased with increases in channel catfish Ictalurus punctatus (Rafinesque) (which are stocked annually) abundance. Fish were not related to the mean size of macroinvertebrates. Macrophyte coverage was not related to macroinvertebrate abundance or mean size. Overall, macroinvertebrate abundance was mostly related to productivity and benthivorous fish in these impoundments. Mean size of macroinvertebrates did not differ with productivity, fish abundance, or macrophyte coverage.