Macroinvertebrate Species Research Articles

Climate model variability leads to uncertain predictions of the future abundance of stream macroinvertebrates

Climate change has the potential to alter the flow regimes of rivers and consequently affect the taxonomic and functional diversity of freshwater organisms. We modeled future flow regimes for the 2050 and 2090 time horizons and tested how flow regimes impact the abundance of 150 macroinvertebrate species and their functional trait compositions in one lowland river catchment (Treene) and one mountainous river catchment (Kinzig) in Europe. We used all 16 global circulation models (GCMs) and regional climate models (RCMs) of the CORDEX dataset under the RCP 8.5 scenario to calculate future river flows. The high variability in relative change of flow among the 16 climate models cascaded into the ecological models and resulted in substantially different predicted abundance values for single species. This variability also cascades into any subsequent analysis of taxonomic or functional freshwater biodiversity. Our results showed that flow alteration effects are different depending on the catchment and the underlying species pool. Documenting such uncertainties provides a basis for the further assessment of potential climate-change impacts on freshwater taxa distributions.

Water column nutrient concentrations are related to excretion by benthic invertebrates in Lake Taihu, China

Internal release of nutrients is an important contributor to the nutrient dynamics in shallow eutrophic lakes. Zoobenthic organisms may contribute to this release by excreting nutrients to the overlaying water. Based on experiments and using results from previous experimental studies as well as field monitoring density data from 2007 to 2017, we calculated the annual and seasonal nutrient excretions of the two most common macroinvertebrates (Corbicula fluminea and Limnodrilus hoffmeisteri) in Lake Taihu, China. We compared these rates with the concentrations of NH4–N, total nitrogen (TN), PO4–P and total phosphorus (TP) in the lake water as well as with previous results of release rates from undisturbed sediments collected in the lake. The spatial distribution of nutrient excretion by the two invertebrate species varied markedly among sites and years. Regression analyses revealed significant relationships between total nutrient excretions by these two species and the concentrations of NH4–N, TN, PO4–P and TP in the lake, but with seasonal differences. The relationship was overall strongest in winter, followed by spring, and weakest in summer and autumn. The flux of NH4–N and PO4–P released by the two macroinvertebrate species were equivalent to as much as 50% and 66%, respectively, of the sediment release recorded in lab experiments under undisturbed conditions; however, the percentages would be somewhat lower under field conditions where the sediment is subjected to frequent wind-induced resuspension and fish disturbance, enhancing the release rates. The release declined during the study period due to a reduction in the density of macroinvertebrates, perhaps indicating increasing stocking of fish since 2007. Our results indicate that benthic invertebrates are important contributor to the internal loading in shallow eutrophic lakes.

An assessment of the ecological functions of a sustainable structured wetland biotope (SSB)

Urban treatment wetlands purify water and provide various ecological services such as food and habitat. We applied the sustainable structured wetland biotope (SSB) system, which considers site-specific ecological conditions and maximizes water purification efficiency, as a treatment wetland for non-point source pollution with short retention time and high biodiversity. This system is consisted of a forebay area (primary retention basin), a micro-pool area (secondary retention basin), and multi-cell structures of marshes and ponds. A wetland constructed with an SSB system for the treatment of non-point source pollution was completed at a site downstream from Jecheon city, located in the upper river basin of the Han River in the Republic of Korea. In addition to the SSB system, a rainwater detention tank for the inflow of the SSB was constructed. During the initial rainfall event, water through SSB were significantly purified (83–98% in BOD, 96–99% in SS, 41–90% in T-N, and 79–96% in T-P of removal efficiency). The flora in the SSB and its neighboring areas consisted of 125 species of 45 families. Three amphibian species, three reptile species, 17 benthic macroinvertebrate species, and 18 avian species were observed in the wetland. We recorded five mammals, including an endangered Eurasian otter species in Korea, Lutra lutra, present in the wetland. Eight fish species were also observed. The wetland showed high removal efficiency without a specific water-treatment device. In addition, local plant and animal species, including rare species, seemed to successfully settle in the SSB.

A comparison of aquatic macroinvertebrate and large branchiopod community composition between temporary pans of a conservation area and surrounding communal area in South Africa

Although temporary wetlands are often biodiversity hotspots that deliver multiple ecosystem services, they are also threatened by human exploitation. We conducted a comparative field study to investigate the impact of reserve protection on the diversity and community structure of aquatic macroinvertebrates of temporary wetlands (pans) in South Africa. Specifically, we compared the diversity and community composition of macroinvertebrates with a special focus on large branchiopod crustaceans in pans of a protected nature reserve (Ndumo Game Reserve) with that of pans in the surrounding anthropogenically disturbed area (Ndumo Communal Area). Our results show that reserve protection has a significant positive effect on the diversity and community structure of the aquatic macroinvertebrates. The taxon diversity for macroinvertebrates in general and large branchiopods in particular was significantly higher in the Ndumo Game Reserve, compared with the Ndumo Communal Area. Overall, our results illustrate the need for continued protection of reserve areas and pans in this tropical region in South Africa for the conservation of macroinvertebrate species.

Benthic macroinvertebrate community characteristics and bioassessment of water quality in the mainstem of upper Hanjiang River and its typical tributaries in the southern slope of the Qinling Mountains

汉江上游是丹江口水库的水源区，其生态环境状况对保障汉江全流域及南水北调中线生态安全起着举足轻重的作用.本研究于2017年11月和2018年4月对汉江上游干流及源于秦岭南麓的5条典型支流开展了系统调查，旨在摸清汉江上游干支流的底栖动物群落特征，以及评价其水质状况.共采集到大型底栖动物240种，其中水生昆虫209种，软体动物13种，环节动物9种，其他类群9种.其中四节蜉Baetis sp.在各条河流中均为优势种，此外其他优势种还有拟细裳蜉Paraleptophlebia sp.、细蜉Caenis sp.、扁蜉Heptagenia sp.、花翅蜉Baetiella sp.、直突摇蚊Orthocladius sp.、纹石蛾Hydropsyche sp.、蜉蝣Ephemera sp.、带肋蜉Cincticostella sp.、高翔蜉Epeorus sp.、似波摇蚊Sympotthastia sp.和真开摇蚊Eukiefferiella sp..从各类群的密度来看，水生昆虫在汉江及五条支流中均占有绝对优势，占总密度的90.8%~98.9%，而在生物量上，除汉江干流中软体动物占绝对优势外，水生昆虫在各支流中均占绝对优势，占总生物量的47.0%~98.9%.就功能摄食类群的密度而言，直接收集者在汉江干支流中均为最主要功能摄食类群，而从生物量方面来看则表现出差异性，捕食者是金水河和旬河中最主要功能摄食类群，刮食者为汉江干流和月河中最主要功能摄食类群，直接收集者是金钱河中最主要功能摄食类群，滤食者为湑水河中最主要功能摄食类群.冗余分析结果表明，流速、总磷和电导率为影响汉江干支流底栖动物分布的关键环境因子.采用底栖动物生物指数（BI）和Shannon-Wiener指数进行水质生物评价，结果显示除汉江的极个别断面、湑水河和月河下游及旬河的中下游河段处于轻-中度污染状态外，其他调查河段均处于清洁状态.本研究结果可为汉江上游流域生态管理和科学保护提供依据.;The upper reaches of the Hanjiang River are the source-water area of the Danjiangkou Reservoir. Its ecological status plays an important role in ensuring the ecological security of the Hanjiang River Basin and the South-to-North Water Transfer Project. In November 2017 and April 2018, we conducted a systematic survey in the upper reaches of the Hanjiang River and its five typical tributaries, in order to find out the characteristics of benthic macroinvertebrate communities in the upper reaches of the Hanjiang River and the typical tributaries of the southern slope of the Qinling Mountains, and to evaluate their bioassessment of water quality. Altogether 240 species of macroinvertebrates were collected, including 209 species of aquatic insects, 13 species of mollusks, 9 species of annelids and 9 species of other groups. Among them, Baetis sp. was the dominant species in all rivers. In addition, other species included Paraleptophlebia sp., Caenis sp., Heptagenia sp., Baetiella sp., Orthocladius sp., Hydropsyche sp., Ephemera sp., Cincticostella sp., Epeorus sp., Sympotthastia sp. and Eukiefferiella sp. From the density of various groups, aquatic insects had an absolute advantage in the Hanjiang River and its five tributaries, accounting for 90.8%-98.9% of the total density. In terms of biomass, in addition to the absolute advantage of mollusks in the main stream of the Hanjiang River, aquatic insects had an absolute advantage in each tributary, accounting for 47.0%-98.9% of the total biomass. In terms of the density of functional feeding groups, direct collectors were the main functional feeding groups in the Hanjiang River and its tributaries, while there were differences in terms of biomass. The predators were the main functional feeding groups in the Jinshui River and the Xun River. The scrapers were the main functional feeding group of the Hanjiang River and the Yue River. The collector-gatherers were the main functional feeding group in the Jinqian River. The collector-filterers were the main functional feeding group in the Xushui River. The redundancy analysis results showed that velocity, total phosphorus and conductivity were the key environmental factors affecting the distribution of benthic macroinvertebrate in the Hanjiang River and its tributaries. The bioassessment of water quality was carried out by using the biotic index (BI) and the Shannon-Wiener index. The evaluation results showed that a few stream sections of the Hanjiang River, the downstream of the Xushui River, the downstream of the Yue River and the mid-lower reaches of the Xun River were slightly to moderately polluted, the other stream sites were in a clean state. The research results can provide basis for ecological management and scientific protection in the upper reaches of the Hanjiang River.

Altitudinal zonality and natural zoning as factors of bottom invertebrate communities formation in lakes of Western Siberia and Russian Altai

In 2003-2016 and 2018, macrozoobenthos from 60 lakes of Western Siberia and the Russian Altai was studied. The lakes refer to high- and medium-altitudinal zones as well as steppe, forest-steppe and taiga natural zones. In lakes under study, we identified 183 species of macroinvertebrates from 10 classes: Demospongiae (1 species), Nematoda (1), Oligochaeta (7), Hirudinea (5), Phylactolemata (1), Bivalvia (4), Gastropoda (10), Arachnida (1), Crustacea (2) and Insecta (151). Species number, species diversity, abundance and biomass of macrozoobenthos in high-altitudinal and natural zones differed both in their average values and within individual zones and belts. Among major factors responsible for benthic communities development in the mountain lakes were water temperature and nutrients content in water, whereas in the lowland water bodies salinity and humification of water.

Structure of macroinvertebrate communities and bioassessment of water quality in the Weihe River mainstream and its typical tributaries from the northern Qinling Mountains

为摸清渭河干流及源于秦岭北麓典型支流的大型底栖动物群落特征，本研究于2017年10月和2018年5月对渭河干流及秦岭北麓5条典型支流共40个样点的大型底栖动物进行调查，并利用Margalef丰富度指数和生物指数BI生物指数对河流水质进行评价.共鉴定大型底栖动物210种，属于5门8纲75科187属.水生昆虫为优势类群，其物种数占总物种数的89.0%，且四节蜉属一种（Baetis sp.）作为绝对优势的物种出现在所有调查河流中.源于秦岭北麓的支流石头河底栖动物总密度最高（616.3 ind./m²），总生物量最大（5.265 g/m²）；而渭河干流底栖动物总密度最低（125.6 ind./m²），总生物量最小（0.289 g/m²）.水质较好的秦岭北麓典型支流底栖动物的Shannon-Wiener多样性指数、Margalef丰富度指数显著高于渭河干流，而Pielou均匀度指数在干支流间的差异性不大.通过Pearson相关分析和多元逐步回归分析得出，淤泥型底质、电导率、pH和硝酸盐氮是影响调查河流底栖动物群落特征的主导因子.丰富度指数法和生物指数法水质评价结果分别显示，渭河干流有73.3%和80.0%的采样点呈中度-重度污染状态，秦岭北麓典型支流有80.0%和68.0%的采样点呈无污染-轻度污染状态.本研究可为渭河流域生态管理与保护提供基础的数据支撑.;For exploring the macroinvertebrate community characteristics of the Weihe River mainstream and its typical tributaries originating from the northern Qinling Mountains, investigation of water environment and macroinvertebrates was conducted in 40 sampling sites in October 2017 and May 2018. Furthermore, Margalef richness and biological index (BI) biological indices were used to assess the water quality of studied rivers. Altogether 210 macroinvertebrates species were identified, belonging to 187 genera, 75 families, 8 classes and 5 phyla. Aquatic insects were the dominant group, accounting for 89.0% of the total species number, and the Baetis sp. was the dominant species in all studied rivers. The tributary Shitou River, had the highest values of total density(616.3 ind./m²), and the highest total biomass(5.265 g/m²). Whereas the total density (125.6 ind./m²) and total biomass (0.289 g/m²) of macroinvertebrates were both lowest in the Weihe River mainstream. The Shannon-Wiener diversity index(H')and Margalef richness index(R)of five typical tributaries were characterized by good water quality and significantly higher than those of the Weihe River mainstream, whereas the Pielou evenness index(J)showed insignificant difference between mainstream and tributaries. Pearson correlation analysis and the multiple linear regression analysis showed that “Silt plus clay” type substrate, conductivity, pH and nitrate nitrogen were the primary environment factors effecting the macroinvertebrate community characteristics in studied rivers. According to the water quality evaluation results of the richness index and the BI method, 73.3% and 80.0% of the mainstream sites were identified as moderately to heavily polluted, but 80.0% and 68.0% of tributary sites were identified as non-polluted to slightly polluted. This study can provide basic data supports for ecological management and protection in the Weihe River Basin.

Towards routine DNA metabarcoding of macroinvertebrates using bulk samples for freshwater bioassessment: Effects of debris and storage conditions on the recovery of target taxa

Abstract Macroinvertebrates are commonly sampled for bioassessment of freshwater ecosystems. However, current bioassessment protocols involve laborious sorting of the animals from the debris (sample matrix) and morphological identification, where species level identifications are often difficult. DNA metabarcoding has the potential to improve bioassessment by reducing the time taken to process samples and improve the accuracy and speed of macroinvertebrate species identification. In this study, we evaluated DNA metabarcoding of macroinvertebrate samples, which include macroinvertebrates and the debris collected in the sample nets, to test if bulk, unsorted samples can be used to assess macroinvertebrate diversity. First, we tested if the sample matrix prevented the detection of six target macroinvertebrate taxa when DNA metabarcoding. Second, we tested if sample storage influenced the detection of the same six target macroinvertebrates. We also explored different levels of replication at the sample, sub‐sample, and polymerase chain reaction levels and compared the overall macroinvertebrate families detected using DNA metabarcoding to those identified morphologically. We found that the presence of the sample matrix did not interfere with or inhibit the detection of the six target macroinvertebrate taxa. Furthermore, we found that the various sample storage methods did not affect target macroinvertebrate detection. The reliability of detection of the target macroinvertebrates improved as hierarchical levels of replication were combined. We found strong overlap between the detection of overall macroinvertebrate family diversity when comparing DNA metabarcoding to morphological identification. Extracting DNA from the bulk macroinvertebrate samples that included the sample matrix and using this for DNA metabarcoding could improve bioassessment by removing the need for laborious sorting of samples. Furthermore, DNA metabarcoding detection of the six target taxa was not dependent on sample storage of up to 1 year in 95% ethanol, at room temperature or after heating. DNA metabarcoding had the advantage of identifying macroinvertebrate species, but good DNA barcode libraries are needed for widespread species identifications. Further investigation should focus on including multiple samples with different macroinvertebrate composition and densities to refine and standardise bulk sample processing protocols, and on building comprehensive DNA barcode libraries for aquatic macroinvertebrates.

Beavers alter stream macroinvertebrate communities in north‐eastern Utah

Abstract Understanding changes in macroinvertebrate communities is important because they play a large role in stream ecosystem functioning, and they are an important food resource for fish. Beaver‐induced changes to stream morphology could alter macroinvertebrate communities, which in turn could affect food webs and ecosystem function. However, studies investigating the effects of North American beaver activities on macroinvertebrates are rare in the inter‐mountain west, an area with high potential for beaver‐assisted restoration. The aim of this study was to quantify differences in the macroinvertebrate community between unaltered segments of streams and within beaver ponds in north‐eastern Utah, U.S.A. We assessed macroinvertebrate species richness, biomass, density, functional feeding group composition, mobility group composition, and macroinvertebrate habitat characteristics to test the hypothesis that macroinvertebrate communities will differ among habitat types (undammed stream segments and beaver ponds) in beaver‐occupied streams. Beaver pond communities significantly differed from lotic reach communities in many ways. Beaver ponds were less diverse with 25% fewer species. Although there was variability among streams, in general, beaver ponds had 75% fewer individuals and 90% lower total macroinvertebrate biomass compared to lotic reaches. Regarding functional feeding groups, beaver ponds contained more engulfers, while lotic reaches contained more scrapers, filterers, and gatherers. For mobility groups, beaver ponds had more sprawlers, while lotic reaches had more clingers. Swimmers were also more prevalent in lotic reaches, although this is probably due to the abundance of Baetis within lotic reaches. More beaver pond taxa were classified as lentic‐dwelling insects, while more lotic reach taxa were categorised as preferring lotic habitats. The creation of ponds by beavers fundamentally altered the macroinvertebrate community in north‐eastern Utah streams. Such changes to stream macroinvertebrate communities suggest that recolonisation of beavers across North America may be altering stream functioning and food webs. Our study highlights the need to further investigate the effects of beaver recolonisation on stream communities.

How can interspecific interactions in freshwater benthic macroinvertebrates modify trace element availability from sediment?

This study aimed to assess how bioturbation by freshwater benthic macroinvertebrates with different biological traits alone or in combination could modify trace elements (TE) fate between sediment and water, and if water TE concentration and animal TE content impair their body stores. Three macroinvertebrate species were exposed to TE contaminated sediment for 7 days: the omnivorous Echinogammarus berilloni (Amphipoda), the sediment feeding Tubifex tubifex (Oligochaeta) and the filter feeding Pisidium sp. (Bivalvia). Treatments were one without invertebrates (control), two with amphipods or mussels alone, and the combinations amphipod-mussel, and amphipod-mussel-worms. Water TE concentration increased significantly in 2 or 3 species mesocosms, concerning mainly Rare Earth Elements, Cr, U and Pb, known to be associated to the colloidal phase. By contrast, water soluble TE were not affected by animals. For both, amphipods and mussels, TE body content increased with the number of coexisting species. For amphipods, this increase concerned both, soluble and colloid-associated TE, possibly due to intense contact and feeding from sediment and predation on tubificids. TE bioaccumulation in mussel was less important and characterized by soluble TE, with water filtration as most plausible uptake route. Protein, triglyceride and Whole Body Energy Budget increased in amphipods with the number of coexisting species (probably by feeding on mussels' feces and tubificids) whereas triglycerides declined in mussels (presumably filtration was disturbed by amphipods). This study highlights interspecific interactions as key drivers explaining both: TE bioturbation, depending on their water solubility or colloidal association, and the exposure/contamination of species through another species activity.

Mercury dynamics in macroinvertebrates in relation to environmental factors in a highly impacted tropical estuary: Buenaventura Bay, Colombian Pacific

The environmental health of Buenaventura Bay, a highly impacted tropical estuary, is influenced by numerous human activities, including mining upstream. Large- and small-scale fishing plays an important role in the local economy, so we investigated the dynamic processes of bioaccumulation of mercury at basal trophic levels. Four samples were taken at each of the four locations in Buenaventura Bay during each of the four seasons of 2015. We measured the total mercury content (T-Hg, dry weight) in sediments and in muscle tissue across 17 macroinvertebrate species. The most abundant were the blue crab (C. arcuatus) and the mantis shrimp (S. aculeata aculeata). Blue crab showed an average muscle T-Hg value ​​exceeding the limit of 0.2 g·g-1, which is the maximum T-Hg level suggested for food consumption by vulnerable humans and populations: pregnant women, children, and the community that feeds from this source of protein on a daily basis. It was found that, 6.22% of individuals exceeded the 0.5 g·g-1 level, which is the maximum T-Hg level suggested for food consumption by the general population: the population that consumes it sporadically. Significantly high values ​​of T-Hg in blue crab and mantis shrimp occurred during low salinity conditions in the estuary, suggesting that Hg mainly originates from river runoff during the rainy season. Nevertheless, the biota-sediment accumulation factor (BSAF) was favored in high salinity, which could mean greater availability of Hg for higher levels of the estuarine food web in the dry season and in marine waters. In general, the T-Hg levels in some samples exceeded 0.2 g·g−1. Therefore this pollutant must be monitored due to its biomagnification potential and as a threat to human health, especially that for the local population of fishermen and their families.

Potential physical effects of suspended fine sediment on lotic macroinvertebrates

This study investigates the potential for physical damage caused by suspended fine sediment on gills of three macroinvertebrate species, Hydropsyche siltalai, Ephemera danica and Ecdyonurus venosus. Macroinvertebrate cadavers were exposed to three suspended sediment concentrations (control 3.5, low 83.7 and high 404.0 mg l−1) at two velocities (low 0.19 m s−1 and high 0.37 m s−1), for 6 h in a recirculating flume. Tracheal gill surfaces were subsequently examined for evidence of physical damage using scanning electron microscopy (SEM) images. Physical damage predominantly consisted of fine sediment coverage of gill surfaces, appearing as a deposited layer of sediment obscuring and potentially clogging the gill. For E. venosus, suspended sediment concentration influenced gill cover, but velocity had no significant effect. Coverage of H. siltalai gill surfaces increased significantly between low and high sediment concentrations but only at the higher flow velocity. Gill coverage of E. danica did not differ across any sediment concentration. The results were consistent with reported species sensitivities to fine sediment, despite the use of cadavers. However, we found limited evidence of physical abrasion as a direct physical effect of fine sediment under the experimental conditions used.

Identifying and applying an optimum set of environmental variables in species distribution models

ABSTRACTPredictive models such as species distribution models (SDMs) are increasingly applied to inform conservation efforts and management decisions. A thoughtful predictor choice, and hence the variable selection process, is a challenge when modeling large communities. Often, variable choice is made for an entire community and not for specific species, resulting in less appropriate predictors for at least some species and affecting model performance and predicted distributions. Using 2 German river catchments as a model system, we investigated (1) application of boosted regression trees (BRTs) as a variable selection procedure to choose the optimal set of environmental predictors and (2) whether model performance is increased by applying custom-made predictor sets to individual species. From a community of 67 benthic macroinvertebrate species, 10 increased in accuracy with the customized predictor set and 10 species decreased in accuracy. Notably, current preference, stream notation, and functional group differed between these species’ groups, which correspond to varied environmental conditions in their known occurrence sites. The species that increased in accuracy showed a preference toward lowland conditions and were far less widespread than the species that decreased in accuracy. We conclude that BRTs are a useful tool for selecting variables for SDMs on large communities. Also, for specialist, rare, or invasive species, determining a species-specific custom-made predictor set may be preferable because species’ preferences may not be representative of the entire study area. Our study describes a structured variable selection approach that can be readily implemented to predict species distributions informative for river management decisions.

Macroinvertebrates and Microbes (Archaea, Bacteria) Offer Complementary Insights into Mine-Pit Lake Ecology

The broad objective of this research was to determine the environmental drivers of macroinvertebrate and microbial assemblages in acidic pit lakes. This is important because pit lake ecosystem development is influenced by prevailing environmental characteristics. Three lakes (Stockton, Kepwari, WO5H) within a larger pit-lake district in Collie, Western Australia were surveyed for spatial variability of benthic macroinvertebrate and microbe (Archaea, Bacteria) assemblage composition as well as potential environmental drivers (riparian condition, aquatic habitat, sediments, and aquatic chemistry) of assemblages. With the exception of sediment chemistry, biophysical variables were significantly different across lakes and reflected riparian condition and groundwater chemistry. Microbial assemblages in pit lakes were significantly different across lakes and correlated with water chemistry, particularly metals in Lake WO5H. However, the most abundant microbes were not readily identified beyond class, making it difficult to speculate on their ecological function. Macroinvertebrate assemblage composition and species richness were also significantly different across all lakes, and in Lake WO5H (a lake with low pH and high metal concentrations), taxa were correlated with benthic organic matter as well as water chemistry. Results indicated that despite poor water quality, input of nutrients from terrestrial leaf litter can support or augment pit lake ecosystems. This is a demonstration of the concept that connection of pit lakes to catchments can positively affect aquatic ecosystems, which can inform management actions for remediation.

Relationships between soil macroinvertebrates and nonnative feral pigs (Sus scrofa) in Hawaiian tropical montane wet forests

Nonnative feral pigs (Sus scrofa) are recognized throughout the New World as a highly significant introduced species in terms of ecosystem alteration. Similarly, nonnative soil macroinvertebrates (e.g. earthworms, ground beetles) invade and alter the structure and function of native habitats globally. However, the relationship between feral pigs and soil macroinvertebrates remains largely unknown. This study analyzed relationships between these taxa using nine sites located inside and outside of feral pig management units representing a ~ 25 year chronosequence of removal in tropical montane wet forests in Hawai‘i. Soil macroinvertebrates were sampled from plots categorized as: actively trampled by feral pigs, actively rooted by feral pigs, feral pigs present with no signs of recent activity, or feral pigs removed over time. In total, we found 13 families of primarily nonnative soil macroinvertebrates. Plots with active trampling correlated with lower total macroinvertebrate abundance, biomass, and family richness. Plots with active rooting were correlated with higher abundance of nonnative earthworms (Lumbricidae and Megascolicidae) and ground beetles (Carabidae). The abundance, biomass, and biodiversity of macroinvertebrates did not vary with time since feral pig removal. Collectively, these results indicate: (1) trampling by feral pigs negatively influences soil macroinvertebrates; (2) feral pigs either modify habitats while rooting thereby facilitating earthworm and ground beetle habitat use or selectively seek out target prey species of soil macroinvertebrates; and (3) removal of feral pigs has minimal impacts on soil macroinvertebrates over time. These results are important globally due to the broadly overlapping ranges of S. scrofa and nonnative macroinvertebrates.

New Species of Bottom Macroinvertebrates for the Fauna of Kalmykia

A list of 17 species of bottom macroinvertebrates that are recorded in water bodies of Kalmykia for the first time is presented: six chironomid species, four mollusk species, three oligochaete species, one short-palped cranefly species, one dragonfly species, one horsefly species, and one biting midge species. The location of these species and their ecological and faunistic characteristic are given. All identified species are generally widespread in Russia.

Sandification vs. muddification of tidal flats by benthic organisms: A flume study

Bioturbating benthic organisms have typically been characterised by how they modify the vertical sediment erosion thresholds. By means of several annular flume experiments, we aimed to understand how benthic organisms may affect grain-size sediment properties over time, and how this depends on the sediment type and the sediment loading of the water column. We compared the effect of two bioturbating macroinvertebrate species: a local dominant species, the cockle Cerastoderma edule and a spreading non-indigeneous species, the clam Ruditapes philippinarum. Our results indicate that the effect of benthic organisms on sediment dynamics is strongly dependent on both the prevailing environmental conditions and the benthic species present. If sediment is sandy, the benthos can gradually enhance the silt content of the sediment by mixing in part of the daily tidal sediment deposition. In contrast, if sediment is muddy, benthos can gradually decrease the silt content of the sediment by specifically suspending the fine fraction. Moreover, we observed that the native cockles had a stronger impact than invasive clams. Therefore, bioturbating benthos can have an important effect in determining the local sediment properties, with the outcome depending both on the species in question and the environmental conditions the bioturbator lives in. Our findings show that sediment bioturbation may have strong implications for tidal flat stability undergoing major changes from natural or anthropogenic sources.

Ecological evaluation of weir removal based on physical habitat simulations for macroinvertebrate community

In Korea, rapid urbanization has changed the land use in rural areas, which has resulted in an increase in the number of weirs that are left untended in streams. Previously, changes in stream morphology and fishes were studied following the removal of such weirs. The present study was conducted to investigate changes in the habitat of the macroinvertebrate community after weir removal using physical habitat simulations (PHSs). The functional group approach was used in the PHSs for the macroinvertebrate community. In the functional group approach, macroinvertebrates are classified based on the traits of their food acquisition (i.e., the functional feeding group) or habitat selection (i.e., the functional habit group). In the present study, macroinvertebrate species were divided into the functional habit groups (FHGs) of swimmers, clingers, burrowers, and sprawlers. Hydraulic simulations and habitat simulations were carried out using the River2D model and habitat suitability curves (HSCs), respectively. The distributions of the composite suitability index (CSI) for the FHGs were obtained over the entire study area, and the changes in the suitability of the habitat for the target FHGs were evaluated. The simulation results indicated that habitat suitability for swimmers, clingers, and sprawlers was improved. However, habitat suitability for burrowers was degraded after the weir was removed. Consequently, the removal of the weir increased the diversity of the macroinvertebrate community, thus improving the health of the aquatic ecosystem.

What Works? the Influence of Changing Wastewater Treatment Type, Including Tertiary Granular Activated Charcoal, on Downstream Macroinvertebrate Biodiversity Over Time.

The present study reviewed the impacts of wastewater on macroinvertebrates over 4 decades in a United Kingdom lowland river. This involved examining changes in chemicals, temperature, flow, and macroinvertebrate diversity from the 1970s until 2017 for a wastewater‐dominated river downstream of Swindon in the United Kingdom (population ~ 220 000). When the wastewater treatment process changed from trickling filter to activated sludge in 1991, biological oxygen demand was nearly halved (90th percentile from 8.1 to 4.6 mg/L), ammonia peaks dropped more than 7‐fold (90th percentile from 3.9 to 0.53 mg/L), whereas dissolved oxygen climbed consistently above 60% saturation (10th percentile from 49 to 64%) at a sampling point 2 km downstream of the wastewater treatment plant. A sustained increase in the number of macroinvertebrate species was evident from that point. River flow did not change, temperature rose slightly, and the major metal concentrations declined steadily over most of the monitoring period. Neither the introduction of phosphate stripping in 1999 nor the use of tertiary granular activated charcoal from 2008 to 2014 had strong positive effects on subsequent macroinvertebrate diversity. That the diversity still had not reached the ideal status by 2016 may be related to the modest habitat quality, agricultural pesticides, and limited recolonization potential in the catchment. The results indicate that urban wastewaters, with their chemical pollutants, are today probably not the biggest threat to the macroinvertebrate diversity of multiply stressed lowland rivers in the United Kingdom. Environ Toxicol Chem 2019;38:1820–1832. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC

Quantifying cumulative stress acting on macroinvertebrate assemblages in lowland streams

Macroinvertebrates in lowland streams are exposed to multiple stressors from the surrounding environment. Yet, quantifying how these multiple stressors impact macroinvertebrate assemblages is challenging. The aim of this study was to develop a novel method to quantify the cumulative stress acting on macroinvertebrate assemblages in lowland streams. To this purpose, we considered 22 stressors from different stressor categories such as hydrological, morphological and chemical stressors, acting over multiple spatial scales ranging from instream to the catchment scale. Stressor intensity was categorized into classes based on impact on the macroinvertebrate assemblages. The main stream was divided into segments, after which for each stream segment, the cumulative stressor contribution from headwater catchments, from the riparian zone and from upstream was calculated. To validate the cumulative stress quantification method, the lowland stream Tungelroyse Beek in the Netherlands was used as a case study. For this stream it was shown that independently derived ecological quality scores based on macroinvertebrate samples collected at multiple sites along the stream decreased with increasing calculated cumulative stress scores, supporting the design of the cumulative stress quantification method. Based on the contribution of each specific stressor to the cumulative stress scores, the reasons for the absence and presence of macroinvertebrate species may be elucidated. Hence, the cumulative stress quantification method may help to identify and localize the most stringent stressors limiting macroinvertebrate assemblages, and can thereby provide a better focus for management resources.