Aquatic Insect Communities Research Articles

Further evidence for a global decline of the entomofauna

AbstractThe Anthropocene is characterised by pervasive human‐inflicted impacts on a broad range of biota, including insects. In 2019, we reviewed scientific literature quantifying the prevalence and magnitude of insect declines in recent time. Here, drawing upon 40 additional long‐term studies, we add evidence that is consistent with our earlier review and some other reviews on the fate of insect populations globally. New data for Greenland, northern Africa, South America, eastern Asia and Australia complement studies from Europe and North America. Temporal trends in insect populations are now derived from 100 long‐term studies and refer mainly to the past three or four decades (median 33 years). Data from the 10 major insect taxonomic orders indicate that an average 37% of species are declining in numbers, while populations of 18% species are increasing; the latter taxa mainly involve agricultural herbivores and nuisance pests. Population changes are more pronounced among aquatic insect communities, where 42% of species are declining and 29% increasing. Such changes result in a decrease in biomass across taxa, except for Heteroptera. Changes in species richness and diversity indices are inconsistent and do not reflect intraspecific population changes over time. These trends are observed irrespective of taxon, geography or methodological approach, although a lack of long‐term monitoring records prevents a proper assessment for tropical regions.

Aquatic insect communities in headwater streams of Ciliwung River watershed, West Java, Indonesia

Abstract. Wakhid, Rauf A, Krisanti M, Sumertajaya IM, Maryana N. 2021. Aquatic insect communities in headwater streams of Ciliwung River watershed, West Java, Indonesia. Biodiversitas 22: 30-41. Ciliwung is one of the major rivers flowing from Cisarua (Bogor) to Jakarta. This study was conducted to assess and compare aquatic insect biodiversity and community structure in various headwater streams with respect to different land-use types. Ten stream reaches of the first and second orders representing three different land-use types in the surrounding area (forest, tea plantation, village) were selected. At each stream reach, the aquatic insects were collected using a D-net (0.4 mm mesh). Physico-chemical properties of water were directly measured in the field. Samples were collected every two months from April until December 2018. A total of 26531 aquatic insect specimens belonging to 75 species/morphospecies, 46 families, and 10 orders were recorded. The order Trichoptera was the most abundant comprising 51.28% of the total collected insects, followed by Diptera (30.5%), Ephemeroptera (7.52%), and Plecoptera (6.25%). The highest proportion of functional feeding group was filtering-collectors (61.34%), followed by shredders (16.29%), gathering-collectors (15.32%), and predators (6.94%). Abundance of Diptera and Plecoptera was significantly higher in forest streams, while Ephemeroptera in plantation streams, and Trichoptera in village streams. The peak population of Diptera, Ephemeroptera, and Trichoptera occurred in June (dry period), while Plecoptera in December (wet period). The forest streams exhibited the highest species richness and diversity. Analysis of similarity (ANOSIM) showed a low dissimilarity among streams of the three land uses (Global R=0.217; P<0.001). The non-metric multidimensional scaling (NMDS) analysis showed that forest streams somewhat separated from plantation and village streams. The study provided important information on aquatic insect biodiversity, and indicated the need for forest area preservation in the headwater streams of Ciliwung River watershed.

Responses of Aquatic Nontarget Organisms in Experiments Simulating a Scenario of Contamination by Imidacloprid in a Freshwater Environment.

Several studies have indicated the presence of the neonicotinoid insecticide imidacloprid (IMI) in aquatic ecosystems in concentrations up to 320.0µgL-1. In the present study, we evaluated the effects of the highest IMI concentration detected in surface water (320.0µgL-1) on the survival of Chironomus sancticaroli, Daphnia similis, and Danio rerio in three different scenarios of water contamination. The enzymatic activities of glutathione S-transferase (GST), catalase (CAT), and ascorbate peroxidase (APX) in D. rerio also were determined. For this evaluation, we have simulated a lotic environment using an indoor system of artificial channels developed for the present study. In this system, three scenarios of contamination by IMI (320.0µgL-1) were reproduced: one using reconstituted water (RW) and the other two using water samples collected in unpolluted (UW) and polluted (DW) areas of a river. The results indicated that the tested concentration was not able to cause mortality in D. similis and D. rerio in any proposed treatment (RW, UW, and DW). However, C.sancticaroli showed 100% of mortality in the presence of IMI in the three proposed treatments, demonstrating its potential to impact the community of aquatic nontarget insects negatively. Low IMI concentrations did not offer risks to D. rerio survival. However, we observed alterations in GST, CAT, and APX activities in treatments that used IMI and water with no evidence of pollution (i.e., RW and UW). These last results demonstrated that fish are more susceptible to the effects of IMI in unpolluted environments.

William E. Walton 1956–2020

William E. Walton 1956–2020

The role of environmental and spatial factors in the assembly of aquatic insect communities in southern Brazilian temporary ponds

AbstractMetacommunity organisation in temporary ponds is assembled by spatiotemporally varying processes that are also contingent on the species’ dispersal ability and scale of observation. Aquatic insects are useful models to study the relative contribution of environmental and spatial factors to community assembly in view of the differing dispersal ability existing in the species from this group. We assessed the metacommunity organisation of aquatic insects and subsets of strong‐ and weak‐flying insects in relation to environmental (habitat structure; water chemistry; climate) and spatial factors in temporary ponds ranging along a latitudinal gradient in southern Brazil. Local and climate environmental factors (water chemistry and temperature) along with fine‐scale spatial factors were the main drivers of the total insect community, although their relative importance shifted between subsets of weak‐ and strong‐flying insects. The composition of strong‐flying insects was structured by climate and fine‐scale spatial factors, while weak‐flying insects, by local (water chemistry) and spatially structured climate. This suggests that strong‐flying insects showed stronger signatures of mass effects at finer scales, while weak‐flying insects were more strongly affected by species sorting coupled to local environmental factors and regional climate. In summary, our results indicate that the relative importance of assembly processes for metacommunity organisation of aquatic insects in temporary ponds is contingent on dispersal ability.

Effects of Environmental Variables and Habitat Integrity on the Structure of the Aquatic Insect Communities of Streams in the Cerrado-Caatinga Ecotone in Northeastern Brazil

Alterations in the environmental gradients of streams have a direct influence on the structure of the insect communities of the orders Ephemeroptera, Plecoptera, and Trichoptera (EPT), which are extremely sensitive to changes in habitat. The present study evaluated how habitat integrity in streams influence the composition of EPT genera, by testing three hypotheses: (i) the composition of the EPT genera is modified along the gradient of environmental disturbance; (ii) the composition of the EPT genera is more homogeneous in gradients with a higher degree of anthropogenic disturbance, and (iii) the greatest degree of environmental disturbance along the gradient results in the reduction of the richness and abundance of EPT genera. The study focused on 14 tributaries of the middle Itapecuru River, within an area of ecotone between the Brazilian Cerrado and Caatinga biomes. Data on the structure and physicochemical traits of the streams were collected between September 2014 and July 2015, a period that covers both the dry and rainy seasons in the study region. The results of the present study indicate that the composition of the EPT genera is modified in accordance with the variation in the habitat integrity, although, in contrast with expectations, more impacted areas had a more heterogeneous composition than undisturbed ones. The areas with more integrated landscapes contribute positively to the richness and abundance of EPT genera of the streams of the Cerrado-Caatinga ecotone. Given this, habitat integrity provide an important predictor of EPT diversity in the streams of the Cerrado-Caatinga ecotone.

Effects of Local Environmental and Landscape Variables on the Taxonomic and Trophic Composition of Aquatic Insects in a Rare Forest Formation of the Brazilian Amazon.

In the present study, we analyzed a unique phytophysiognomy in the Amazon region, which is formed by savanna-like vegetation on iron-rich soil (known locally as canga) located within an iron-ore mining region. We used the habitat template theory to test the hypothesis that changes in the physical-chemical properties of streams and the physical structure of their habitats at in-stream and micro-basin (landscape) levels affect the taxonomic and trophic composition of immature aquatic insects. For this, we used a local environmental matrix composed of nine physical-chemical and structural habitat variables, together with the Habitat Integrity Index. We also calculated landscape metrics based on the area of the micro-basin, such as relief, slope, mean current flow, and vegetation cover. We divided the aquatic insects into five functional feeding groups based on their diet and food sources. Our results indicate that changes in the trophic level of the insects of the orders Ephemeroptera, Plecoptera, and Trichoptera are more easily observed than the taxonomic structure of communities. The loss of environmental integrity and vegetation cover were responsible for 84% of the variation observed in the composition of functional feeding groups (FFGs). Our study shows that aquatic insect communities in the canga and in the Amazon regions dominated by forest require specific in-stream and landscape conditions. These findings reinforce the need for the preservation of areas of canga vegetation, which not only have a unique levels of biological diversity, but are also targeted for the exploitation of their economically valuable natural resources.

Aquatic insect community structure revealed by eDNA metabarcoding derives indices for environmental assessment.

Environmental DNA (eDNA) analysis provides an efficient and objective approach for monitoring and assessing ecological status; however, studies on the eDNA of aquatic insects, such as Ephemeroptera, Plecoptera, and Trichoptera (EPT), are limited despite its potential as a useful indicator of river health. Here, we investigated the community structures of aquatic insects using eDNA and evaluated the applicability of eDNA data for calculating assessment indices. Field surveys were conducted to sample river water for eDNA at six locations from upstream to downstream of two rivers in Japan in July and November 2016. Simultaneously, aquatic insects were collected using the traditional Surber net survey method. The communities of aquatic insects were revealed using eDNA by targeting the cytochrome oxidase subunit I gene in mitochondrial DNA via metabarcoding analyses. As a result, the eDNA revealed 63 families and 75 genera of aquatic insects, which was double than that detected by the Surber net survey (especially for families in Diptera and Hemiptera). The seasonal differences of communities were distinguished by both the eDNA and Surber net survey data. Furthermore, the total nitrogen concentration, a surrogate of organic pollution, showed positive correlations with biotic environmental assessment indices (i.e., EPT index and Chironomidae index) calculated using eDNA at the genus-level resolution but the indices calculated using the Surber net survey data. Our results demonstrated that eDNA analysis with higher taxonomic resolution can provide as a more sensitive environmental assessment index than the traditional method that requires biotic samples.

Chemistry of streams draining mined and unmined watersheds in the mountaintop mined landscape of Central Appalachia, USA.

Mountaintop removal coal mining is the predominant form of surface mining in the Appalachian Region of the United States and leads to elevated levels of chemical constituents in streams draining mined watersheds. This data set contains measurements of water chemistry in the mountaintop mined landscape of Central Appalachia. These data were collected to determine the accumulation and transport of mercury (Hg) and selenium (Se) across environmental compartments in mountaintop mining-impacted waters as well as the impact of mountaintop mining on the aquatic-terrestrial subsidy. Samples were collected in summer 2017 and spring/summer 2018. Data predominantly include Se, THg, and methylmercury (MeHg) in the following environmental compartments at sites impacted and unimpacted by mountaintop removal coal mining: water, sediment, biofilm, larval cranefly, adult aquatic insects, and spiders. Additional water parameters that have been found to vary across a gradient of mountaintop mining impact (total organic carbon [TOC], total nitrogen [TN], sulfate [SO4 ], nitrate [NO3 ], chloride [Cl], pH, sodium [Na], potassium [K], magnesium [Mg], calcium [Ca], manganese [Mn], sulfur [S], specific conductance) were also measured. The majority of sites represented are headwater streams, although some settling ponds below valley fills are included. This data set also includes taxonomic characterization of the adult aquatic insect community as well as measurements of spider density at a subset of sites. There are no copyright restrictions; please cite this data paper when the data are used in publications.

How Habitat Filtering Can Affect Taxonomic and Functional Composition of Aquatic Insect Communities in Small Amazonian Streams.

Responses in taxonomic and functional composition of communities were analysed in small Amazonian streams at the small and large scale (habitat patches, river segment scale, and catchment scale). We hypothesised that similar responses in community structure to local environmental factors were a correlation between taxonomic and functional composition. To evaluate the response of taxonomic composition to environmental variables, redundancy analysis (RDA) and RLQ analysis were performed to investigate the response of community abundance (L) as a function of the environment (R) and traits (Q). The fourth-corner analysis was applied to summarize specific interactions between environmental variables and traits. Then, community taxonomic composition was associated with models at multiple scales of habitat (i.e. riparian/channel, substrates, and water variables). Likewise, the fourth-corner tests and RLQ axes showed associations between trait composition and environmental variables related to variables, such as riparian cover and channel morphology followed by variation in substrate size and composition. Unexpectedly, these results did not show specific associations between unique environmental variables and traits. At last, results showed that local conditions of stream habitat regulated community structure and functional composition of aquatic insects. Thus, these findings indicate that the local environmental filtering appears to be strongly associated with selected species traits adapted to occur in a range of habitat conditions. Despite the low number of analysed streams, these results provide important information for understanding the simultaneous variation in functional trait composition and community composition of aquatic insect assemblages.

The effect of lead (Pb) and zinc (Zn) contamination on aquatic insect community composition and metamorphosis

Metal contamination of freshwater ecosystems is a great threat to aquatic insect communities. In the past, focus has been on the toxic effects on the insect larvae, despite emerging evidence showing that negative effects can occur during metamorphosis to adults. There is therefore a risk that traditional studies on insect larvae would underestimate effect from metals. In this study, we investigated the effect of lead (Pb) and zinc (Zn) on aquatic insect abundance, including metamorphosis and adult emergence at 9 lakes, near an abandoned Pb/Zn mine, with different Pb and Zn concentrations in sediment and water. Further, differences in response to metal contamination among taxa, and potential community composition changes, were also investigated. Total insect abundance was not affected by metal contamination, but Zn had a negative effect on metamorphosis and proportionally less adults emerged compared to larval abundance when the bioavailable Zn concentration in water increased. The opposite pattern was found for bioavailable Pb (negative effect on larvae but not on adult emergence). All studied insect groups had similar response to metal contamination, and no change in community structure towards dominance of more tolerant taxa was observed. Our study shows that it is important to include metamorphosis when metal toxicity is evaluated in aquatic insects, and that metals can have opposite and contradicting effects. Thus, although combined cocktail effects of metal mixtures are important to assess, effects of individual metals can be underestimated.

The habitat integrity index and aquatic insect communities in tropical streams: A meta-analysis

Abstract Conversion of natural landscapes into agricultural land-uses represents a major threat to global biodiversity. In lotic ecosystems, aquatic insects are among some of the most vulnerable organisms to such alterations, and thus it is important to study and evaluate how habitat integrity is affected by human activities. In this work we review the Habitat Integrity Index (HII): a measure of environmental integrity of streams. Our objective was to evaluate if this index is a reliable tool for environmental monitoring in tropical streams. We synthesize the relationship between HII and aquatic insect communities in 647 streams in Brazil. Our analysis showed a significant relationship between HII and aquatic insect communities, explaining 29% of variation in community composition and structure. Thus, the HII reflects local environmental quality, as well as wider landscape conditions, making it a good predictor for aquatic and semiaquatic organisms. Our results indicate that HII is a good alternative for aquatic biomonitoring in the Brazilian stream and in other countries that have an Amazon rainforest.

The influence of an in-stream thermal gradient on chironomid emergence during winter

The River Continuum Concept (RCC) predicts that aquatic insect communities undergo predictable changes in composition from headwaters to downstream regions relative to changes in habitat. An important aspect of this change is stream temperature. Studies have been conducted on thermal partitioning of chironomids within the RCC and across streams with different thermal regimes; however, few have focused on effects of fine-scale within-stream temperature variability on winter chironomid composition. Our objectives were to characterize thermal heterogeneity within a small headwater trout stream during winter using slope and Y-intercepts from linear regressions of air–water temperatures and to document patterns of chironomid emergence and taxonomic composition relative to mean water temperatures, regression slopes, and Y-intercepts along stream length. We developed air–water temperature regressions using mean daily air and water temperatures for three headwater trout streams. We assessed similarity in taxonomic composition across sites by collecting and analyzing chironomid surface floating pupal exuviae. We demonstrate that regressions of mean daily air and water temperatures can characterize fine-scale thermal heterogeneity within and among headwater trout streams during winter. We also demonstrate that chironomid taxonomic composition varied at spatial scales substantially less than a kilometer within a stream that possessed significant thermal heterogeneity.

Bioaccumulation and Toxicity of Cadmium, Copper, Nickel, and Zinc and Their Mixtures to Aquatic Insect Communities.

We describe 2 artificial stream experiments that exposed aquatic insect communities to zinc (Zn), copper (Cu), and cadmium (year 2014) and to Zn, Cu, and nickel (year 2015). The testing strategy was to concurrently expose insect communities to single metals and mixtures. Single‐metal tests were repeated to evaluate the reproducibility of the methods and year‐to‐year variability. Metals were strongly accumulated in sediments, periphyton, and insect (caddisfly) tissues, with the highest concentrations occurring in periphyton. Sensitive mayflies declined in metal treatments, and effect concentrations could be predicted effectively from metal concentrations in either periphyton or water. Most responses were similar in the replicated tests, but median effect concentration values for the mayfly Rhithrogena sp. varied 20‐fold between the tests, emphasizing the difficulty comparing sensitivities across studies and the value of repeated testing. Relative to the single‐metal responses, the toxicity of the mixtures was either approximately additive or less than additive when calculated as the product of individual responses (response addition). However, even less‐than‐additive relative responses were sometimes greater than responses to similar concentrations tested singly. The ternary mixtures resulted in mayfly declines at concentrations that caused no declines in the concurrent single‐metal tests. When updating species‐sensitivity distributions (SSDs) with these results, the mayfly responses were among the most sensitive 10th percentile of available data for all 4 metals, refuting older literature placing mayflies in the insensitive portion of metal SSDs. Testing translocated aquatic insect communities in 30‐d artificial streams is an efficient approach to generate multiple species effect values under quasi‐natural conditions that are relevant to natural streams. Environ Toxicol Chem 2020;39:812–833. Published 2020 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work, and as such, is in the public domain in the United States of America.

Aquatic insects and their environmental predictors: a scientometric study focused on environmental monitoring in lotic environmental.

Since early studies about aquatic ecology, it has been found that changes in environmental conditions alter aquatic insect communities. Based on this, the combined study of environmental conditions and aquatic insect communities has become an important tool to monitor and manage freshwater systems. However, there is no consensus about which environmental predictors and facets of diversity are more useful for environmental monitoring. The objective of this work was to conduct a scientometric analysis to identify the main environmental predictors and biological groups used to monitor and manage lotic freshwater systems. We conducted a scientometric study on the Web of Science platform using the following words: stream, river, aquatic insect, Ephemeroptera, Plecoptera, Trichoptera, Odonata, Heteroptera, Chironomidae, bioindicator, environmental change, anthropic, and land use. Although most of the environmental predictors employed are local, intrinsic of freshwater systems using local environmental and associated landscape variables is a better strategy to predict aquatic insect communities. The facets of diversity most used are composition and richness of species and genera, which are not efficient at measuring the loss of ecosystem services and extinction of phylogenetic lineages. Although very important, these functional and phylogenetic facets are poorly explored for this purpose. Even though tropical regions are the most diverse globally and are experiencing major losses of native vegetation, these ecosystems are the least studied, a knowledge gap that needs addressing to better understand the effect of anthropogenic activities on the diversity of aquatic insects.

Оригинальная модификация метода пробоподготовки озёрных отложений для изучения макроостатков личинок хирономид (Insecta: Diptera)

Nonbiting midges (chironomids) comprise a globally distributed family of nematoceran flies with complete metamorphosis. They populate aquatic, semiaquatic, and, more rarely, terrestrial habitats and frequently dominate aquatic insect communities in both abundance and species richness. The larval stage is the longest life period (from several weeks to two years); the adults are ephemeral. All this makes chironomid larvae a very valuable object for investigation of ecological and paleoclimatic changes. The nearly six-year experience of work on the separation and investigation fossil remains of chironomid larvae showed that the generally accepted technique of processing samples of lake sediments has a significant drawback. The standard technique for preparation of samples from lake sediments cores for the study of remains of buried chironomid larvae (whole head capsules and mentums) includes treating the sediment with a 10 % KOH solution. After washing the treated samples on sieves, head capsules of chironomid larvae remain poorly washed from both the soil and alkali. It greatly complicates the work with detecting larva remains and their microscopy. The present article describes the original modification of the technique of chemical treatment of lake bottom sediments for the separating and investigation of the remains of non-biting midges larvae for paleoclimatic and paleoecological reconstructions. A distinctive feature of the developed method is that the precipitate is treated with an HF for 24 hours. Acid treatment of samples is carried out to remove the mineral content. It makes the sediment looser, liquid and less sticky. This significantly improves the quality of sample washing on sieves made of two-layer mill gas with a mesh size of 90-100 microns. The new method provides better washing of sediment samples, which contributes to a more complete separation of larva remains. When using the “alkaline” method, from 2–10 cm3 of wet sediment, about 50–100 (depending on the type of lake and the characteristics of sedimentation) head capsules of chironomid larvae can be selected. In the method we proposed, the standard sample volume was 0.5–2 cm3 of wet sediment. But, the content of the considered head capsules of chironomid larvae in the samples taken for analysis significantly exceeded the average achieved results due to their better washing from sediment. Proposed method is also suitable for treating sediments for palynological analysis. The inventory and the sample preparation algorithm are described and illustrated. Examples of photographic descriptions of the head capsules of larvae of some taxa of chironomids, made with a video eyepiece, are given.

Species richness and diversity of aquatic insects inhabiting rice fields in Bogor, West Java, Indonesia

Abstract. Wakhid, Rauf A, Krisanti M, Sumertajaya IM, Maryana N. 2020. Species richness and diversity of aquatic insects inhabiting rice fields in Bogor, West Java, Indonesia. Biodiversitas 21: 34-42. Rice fields occupy the largest cultivated area in agricultural landscape in Indonesia and support a variety of living organisms, including aquatic insects. This study was conducted with the objective to determine the species richness and diversity of aquatic insects inhabiting rice fields. Sampling was made in March, May, and July 2017 in rice fields at Situgede, Pandansari, and Kawungluwuk (Bogor region, West Java, Indonesia), and carried out by dragging dip net on the bottom along the edge of the rice plots. A total of 3,306 individuals representing 45 species of aquatic insects belonging to 30 genera, 20 families, and seven orders were recorded. Order Hemiptera was the most abundance comprising 28.89% of the total insects collected, followed by Diptera (24.80%), Coleoptera (24.41%), and Odonata (21.42%). Functional feeding group analysis showed that collectors-gatherers had the highest proportion (40 - 46%), followed by predators (23-44%) and scrapers (10-35%). Rank-abundance curve showed low species evenness with the four most abundant species were Micronecta siva (Kirkaldy) (Hemiptera: Micronectidae), Chironomus sp. (Diptera: Chironomidae), Orthetrum sabina (Drury) (Odonata: Libellulidae), and Helochares sp. (Coleoptera: Hydrophilidae). The Shannon-Wiener index showed the lowest value (H’=1.84) at Situgede and the highest (H’=2.05) at Pandansari. Richness estimate and individual-based rarefaction curve revealed that rice fields at Pandansari have more species richness than the other two sites. This study provides some insights into the aquatic insect community of the human-made ecosystem and suggests that the ecological approach to pest management is necessary for maintaining ecosystem health and promoting biodiversity.

Context-Dependent Responses of Aquatic Insects to Metals and Metal Mixtures: A Quantitative Analysis Summarizing 24 Yr of Stream Mesocosm Experiments.

Modernizing water quality criteria to predict how contaminants affect natural aquatic communities requires that we utilize data obtained across multiple lines of evidence, including laboratory, mesocosm, and field studies. We report the results of 29 mesocosm experiments conducted from 1994 to 2017 at the Colorado State University Stream Research Laboratory (Fort Collins, CO, USA). The primary goal of the present study was to quantify responses of aquatic insect communities collected from 8 different locations to different combinations of cadmium (Cd), copper (Cu), iron (Fe), and zinc (Zn). Treatments that included Cu or Fe, either alone or in combination with other metals, were especially toxic to aquatic insects. The results showed that effects of metals were context dependent and varied significantly among the 8 sites where communities were collected. In particular, effects on communities from smaller streams were significantly greater than those from larger streams. Our analyses also showed that several morphological (body size, shape, gills, degree of sclerotization) and life history (voltinism) traits were significantly correlated with sensitivity to metals. Across all taxa and experiments, aquatic insects broadly classified as small (maximum body length <8 mm) were significantly more sensitive to metals than medium or large individuals. These findings demonstrate the advantages of integrating results of mesocosm experiments with species traits to develop a mechanistic understanding of biotic and abiotic factors that influence community responses to contaminants. Environ Toxicol Chem 2019;38:2486-2496. © 2019 SETAC.

Biodiversity of aquatic insects in relation to physico-chemical parameters of Shekh Turab stream

Ecological integrity and their properties of any aquatic environment are important to monitor its stability and any change to the ecological system. The current work was undertaken to study the community of aquatic insects and physio-chemical variables of the Shekh Turab stream in periods extended for two months, one in July and the other in November 2017. The aquatic insects’ samples collected from five sites with three replications/site. The physio-chemical parameters of water were water temperature, air temperature (˚C), pH, electrical conductivity EC (μS.cm-1), total dissolved solid TDS (mg.l-1), dissolved oxygen DO (mg.l-1), BOD5 (mg.l-1), alkalinity (mg CaCO3.l-1), bicarbonate HCO3 (mg.l-1), total hardness (mgCaCO3.l-1), calcium (mg Ca2+.l-1), magnesium (mg Mg2+.l-1), nitrate (mg NO3-N.l-1), chloride (mg.l-1), sodium (mg.l-1), potassium(mg.l-1) and sulfate (mg SO4.l-1). The correlation between physio-chemical parameters and different biological taxa were statistically tested. The correlation analysis showed significant relationship. In phylum Arthropoda, a total of 5 insect species belonging to 2 orders; Ephemeroptera and Diptera depicted the Shesk Turab stream macroinvertebrates. Depending on Shannon-Weiner index, species diversity varied from 0.365 to 0.755 at site 4 and 2 respectively.

Taxonomic sufficiency and effects of environmental and spatial drivers on aquatic insect community

Abstract Studies on aquatic insects have found divergent results when assessing the effects of the environment and spatial structure on the community. The inappropriate choice of taxonomic resolution or variables may be the determinant for such results. We tested whether identification to the family level is enough to approximate results obtained using genus in detecting environmental and spatial effects. We sampled the aquatic insect communities in 110 streams of the Brazilian Cerrado (vegetation type savanna). We used PROTEST analyses to determine the similarity of community configuration at the family and genus resolutions and the overlap of community structure among all pair of insect orders. We used a partial redundancy analysis (pRDA) to determine the effects of environmental and spatial factors, for the entire community and for each insect order individually. The community configurations using family and genus were congruent, as were one-third of orders. The family level reduced the unexplained portion of variance when compared with genus level. Water movement, chemical condition and habitat integrity were relevant for community structure. In addition, the use of family level is a good alternative for studies using aquatic insect communities in Cerrado streams.