Functional Feeding Group Composition Research Articles

Distribution, composition and impact of environmental factors on benthic macroinvertebrates functional feeding groups and ecosystem attributes in river Yaah (East Lekie)

From July 2022 to May 2023, a study was carried out in the Lékié division (Center region) and its objective was to evaluate the composition and distribution of benthic macroinvertebrates functional feeding groups in relation to the characteristics of environmental factors and determine the ecosystem attributes of the Yaah watercourse. For that, in three sampling stations, the collection of water samples for analysis and benthic macroinvertebrates were carried out according to standard methods. The grouping of benthic macroinvertebrates into functional feeding groups was done thanks to the keys and appropriate works. A total of 730 benthic macroinvertebrates belonging to 38 families were identified and the families of Belostomidae (11.51%) and Libellulidae (10.96%) were the most dominant. The 38 families of benthic macroinvertebrates identified were grouped into 5 trophic functional groups, predators (63.29%) and Shredders (22.19%) were largely predominant. The distribution of collectors varied from YA 1 to YA 3. The abundance relative of Shredders decreased from upstream to downstream while that of filters increased earlier and these variations were consistent with the River Continuum Concept. The electrical conductivity was influenced positively the distribution of scrapers and gathering collectors while the suspended solids negatively influenced the distribution of shredders and positively the distribution of predators. The watercourses sampled were heterotrophic, conducive to the development of shredders and dominated by Coarse Particulate Organic Matter and predators.

Bioassessment of multiple stressors in Afrotropical rivers: Evaluating the performance of a macroinvertebrate-based index of biotic integrity, diversity, and regional biotic indices

Many streams and rivers outside conservation areas across the Afrotropics face multiple stressors from land use change, urbanization, and excessive water withdrawals. Thus, there is a need to develop cost-effective tools for assessing and monitoring ecological changes to inform management decisions. Studies utilizing macroinvertebrate communities as indicators of the ecological condition of streams and rivers in the Afrotropics use diverse methods, including diversity, richness, biotic and multimetric indices. However, some of these indices are region- or country-specific, which limits their general use across multiple regions or countries. In this study, we address this challenge by testing and comparing the performance of diversity and richness indices (e.g., Shannon-Wiener and Simpson), regional biotic indices (the African Scoring System Version 5 [SASS5], Tanzanian River Scoring System [TARISS] and a biotic index developed for the Ethiopian highlands [ETHbios]), and a macroinvertebrate-based index of biotic integrity (M-IBI) in assessing the ecological condition of Afrotropical rivers with the transboundary Mara River, Kenya and Tanzania, as a case study. In this study, we analyzed water and habitat quality degradation caused by multiple stressors such as land use change, organic pollution and flow alteration and the corresponding responses in macroinvertebrate communities. We utilized macroinvertebrates data collected from 143 sites covering the entire gradient of the river and its major tributaries in Kenya and Tanzania. To develop the M-IBI, we used 12 metrics that describe macroinvertebrate community richness, composition, tolerance to disturbances (indicator taxa), and the composition of functional feeding groups. Although all the biotic indices were sensitive to poor water quality and human disturbance of the river, the M-IBI performed better than biotic indices (SASS5, Tanzanian River Scoring System, and Ethiopian highlands), diversity and richness indices by having a higher discriminatory ability of site categories according to different levels and types of disturbance. Diversity and richness indices performed poorly and failed to discriminate between stressor gradients in the river. This study demonstrates a need for testing and evaluating indices or protocols before adoption and use in biomonitoring streams and rivers in other countries and regions. There is an even greater need to assess the tolerance of macroinvertebrate taxa before inclusion in biotic indices for improved performance as discriminators of multiple stressors.

Temporal-spatial distribution and ecological evaluation of macroinvertebrate functional feeding groups in Yongding River Basin

We investigated community structure of macroinvertebrate, water environment factors, hydrological factors at 23 sampling sites of the Yongding River basin from spring 2017 (April) to autumn 2017 (November). We analyzed the composition, spatial and temporal distribution of the macroinvertebrate functional feeding groups, as well as their responses to changes in riverine habitat. A total of 78 macroinvertebrate species were identified, with 52, 50 and 53 macroinvertebrate species in spring, summer and autumn respectively. The dominant functional feeding groups were gather-collectors, followed by predators, while the proportion of scrapers, filter-collectors and shredders were extremely low. Dominant species in the three seasons were all gather-collectors, including Orthocladius, Rheotanytarsus, Cricotopus in spring, Glyptotendipes in summer, and Polypedilum, Chironomus, Orthocladius in autumn. Results of redundancy analysis showed that the functional feeding groups of macroinvertebrate community structure were mainly influenced by water temperature, flow velocity, salinity, and total phosphorus in spring, by total phosphorus, dissolved oxygen, conductivity and flow capacity in summer, and by total phosphorus and dissolved oxygen in autumn. Total phosphorus had positive correlation with gather-collectors in all three seasons, indicating that the functional feeding groups of macroinvertebrates were affected by water pollution. The evaluation based on the metrics of functional feeding groups showed that: 1) in terms of material cycle, primary productivity of Guishui River were significantly higher than other regions, and that in autumn were significantly higher than other seasons. The secondary productivity and decomposition capacity of Yanghe River were significantly higher than other regions, and those in spring were significantly higher than other seasons. The autotrophy/heterotrophy of Yanghe River was significantly lower than other regions, and that in spring were significantly higher than other seasons. 2) The longitudinal transport capacity of Sanggan River was significantly higher than other regions, and that in autumn was significantly higher than other seasons. 3) The lateral input capacity of Guishui River was significantly higher than other regions, and that in summer was significantly higher than other seasons.

Corbicula incorporation to indicator parameters to assess the ecological status of northwestern Iberian estuaries

Ecological status classification systems based on biological elements (e.g., macroinvertebrate communities) are dependent on their response to different pressures. However, there is a need to determine if invasive species should be incorporated to indicator parameters (i.e. metrics based on measurements of richness and diversity) or as a pressure affecting such parameters. Moreover, because ecosystem classification systems are lacking for northwestern Iberian estuaries, there is even the possibility to develop a new metric penalizing presence or abundance of invasive species. To increase our understanding on this topic, we analyze the taxonomic and functional responses of benthic macroinvertebrates to Corbicula invasion along the environmental gradient of 12 northwestern Iberian estuaries. Macroinvertebrate assemblages were described and compared between invaded and uninvaded sections. Additionally, to assess differences in community structure, macroinvertebrate assemblages’ similarity was examined between two distinct estuarine sections (freshwater and oligohaline vs transitional water and mesohaline) and among water body types, including and excluding Corbicula from the analysis. The salinity gradient was the main driver explaining changes in macroinvertebrate assemblages and in functional group distribution. Freshwater and transitional water sections clearly differed in macroinvertebrate assemblages and functional groups composition. In addition, differences among river types in macroinvertebrate composition were found. Corbicula inclusion or exclusion from multivariate community analysis significantly affected the results in functional feeding group composition in the Cantabric-Atlantic siliceous river axis type. Nevertheless, considering Corbicula as a pressure at the regional scale did not provide different results in diversity indices calculation. Hence, we argue that because Corbicula eradication is virtually impossible, it should be included as an additional metric evidencing its presence as a negative indication, or be included within other indicator metrics used in the assessment of the ecological status, for instance in invertebrate abundance metrics were its dominance should be indicative of invasion impairment.

The trophic basis of fish assemblages in temperate estuarine and coastal ecosystems

More than half of the fish biomass of coastal rocky reefs depends on zooplankton; however, the trophic basis of estuarine fish assemblages remains unknown. We quantified the trophic basis (i.e. basal energy sources) of fish community biomass inhabiting three habitat types (seagrass, natural reef and artificial reef) in two estuaries, compared with two coastal rocky reef sites. Fish assemblages were surveyed with Baited Remote Underwater Video (BRUVs) and the species abundance, richness and biomass of fish were classified into nine functional feeding groups (6 teleost and 3 elasmobranch). Comparable metrics for coastal fish assemblages were obtained from published surveys using BRUVs. Using the functional feeding group biomass and the group-specific diet composition, the breakdown of energy sources was calculated using a food web analysis. Estuarine reef habitats had different species and different functional feeding group composition than seagrass habitat. The majority of fish biomass in the seagrass habitat was supported by detritus (51% in Botany Bay) or macrophytes (58% in Lake Macquarie). In contrast, zooplankton supported most fish biomass (45–59%) at the coastal reef locations, and in reef habitat in one estuary (35–43%), but not the other estuary (33–34%). Trophic pathways which support fish assemblages, are key in identifying mitigation measures which can help conserve these populations with growing urbanisation of estuaries and coasts.

Functional Feeding Group composition and attributes: evaluation of freshwater ecosystems in Atlantic Forest, Brazil

Abstract: Benthic macroinvertebrates Functional Feeding Group (FFG) have been used to determine aquatic assemblage dynamics and as a biomonitoring tool. The main goals of this study were to assess the effects of stream variables on the abundance and richness of FFGs and evaluate ecosystem attributes (FFG ratios) as a tool to assess ecological conditions of Atlantic Rainforest streams. We sampled 146 sites with different impairment conditions in Rio de Janeiro, Brazil. Richness was significantly different among impairment conditions for all FFGs. Mixed-effect models show that aquatic macroinvertebrate FFGs differed in their responses to abiotic variables for abundance and richness. Also, they were reduced in the impaired sites when compared to intermediate and reference sites. The FFG ratio indicated significant differences along the impairment gradient. The FFG ratio analysis was shown to be a fast and cheap tool that can be used for monitoring aquatic ecosystems in the Atlantic Forest biome. However, further studies are required to calibrate the method specifically for the Atlantic Forest region.

Transplanting macrophytes as a rehabilitation technique for lowland streams and their influence on macroinvertebrate assemblages.

Lowland streams are usually affected by river engineering works that produce the loss of habitat heterogeneity. Our aim was to assess the transplantation of macrophytes with different complexity into a lowland stream which was dredged and widened. Stuckenia pectinata and Hydrocleys nymphoides were collected at an extraction site and installed at a transplant site. The growth and coverage of macrophytes beds were quantified. Taxonomic richness, Shannon-Wiener diversity, abundance, composition and proportion of functional feeding groups of the macroinvertebrate assemblage presented in macrophyte beds were assessed between sites and species. The growth of both macrophytes did not differ significantly between sites and the coverage of transplanted beds increased, therefore they established at the transplant site within a short period. Regarding to macroinvertebrate assemblage, only the functional feeding groups did not show differences between sites. Moreover, the proportion of predators presented differences between macrophytes at the same site, with H. nymphoides having a higher proportion. Our study showed that this technique is suitable for reintroducing these species and is applicable in rehabilitation projects that promote the restoration of habitat heterogeneity deteriorated by river engineering works. Also, we highlight the importance of incorporate macroinvertebrate functional traits to assess the ecological status after rehabilitation.

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.

Functional feeding groups of macroinvertebrates and their relationship with environmental parameters, case study: in Zarin-Gol River

Feeding strategies are typical traits reflecting the adaptation of species to environmental conditions. The aim of this paper was finding of proof that functional feeding groups the benthic macroinvertebrates can be unitized as surrogate for biological assessment. The composition and abundance of functional feeding groups of the benthic macroinvertebrate assemblages were surveyed along the Zarin-Gol River, Iran during winter and spring 2016. Benthic samples were collected using Surber sampler (900 cm2 area) with 3 replicates in 5 stations (agriculture, rural area, forest, fish culture and reference site). Ten environmental parameters including (temperature, Dissolved oxygen, pH, Electric conductivity, etc.) of each station were assessed. A total of abundance (901 individuals) belonging to 30 families and 9 orders were identified. In terms of relative abundance, Collector/Gatherer and Collector/ Filter were the predominant groups at most sampling stations. Shredders had low abundance in all stations and were absent in station two. Principal component analysis and cluster ordination showed that there are two distinct groups of benthic and stations. The implication of the observed pattern of variation in the abundance of functional feeding groups were discussed regarding to the ecosystem functions and water quality assessment.

How do local differences in saltmarsh ecology influence disease vector mosquito populations?

Saltmarsh breeding mosquitoes are an important source of vectors for arboviral transmission. In southern Australia, the most prominent vector borne disease, Ross River virus (Togaviridae: Alphavirus) (RRV), is transmitted by the saltmarsh mosquito (Diptera: Culicidae) Aedes camptorhynchus (Thomson). However, the factors driving the abundance of this mosquito within and among saltmarshes are poorly understood. To predict the abundance of this mosquito within saltmarshes, the environmental conditions and aquatic invertebrate ecology of three temperate saltmarshes habitats were monitored over two seasons. Up to 44% of first-instar mosquito numbers and 21% of pupal numbers were accounted for by environmental variables. Samphire vegetation cover was a common predictor of first-instar numbers across sites although, between saltmarshes, aquatic factors such as high salinity, temperatures less than 22 °C and water body volume were important predictors. The identified predictors of pupal numbers were more variable and included high tides, waterbody volume and alkalinity. The composition of invertebrate functional feeding groups differed between saltmarshes and showed that an increased diversity led to fewer mosquitoes. It was evident that apparently similar saltmarshes can vary markedly in invertebrate assemblages, water availability and conditions through tidal inundations, rainfall or waterbody permanency. The present study advances insight into predictors of vector mosquito numbers that drive the risk of RRV outbreaks.

Assigning functional feeding groups to aquatic arthropods in a Neotropical mountain river

The importance of aquatic arthropods in the processing of organic matter in fluvial systems is well known, but this topic has been poorly studied in Neotropical rivers. In this research, we studied the composition of functional feeding groups (FFGs) associated with differences in elevation in a tropical river in northern Colombia during the wet and dry seasons. Between 2008 and 2013, we collected benthic arthropods at 3 sites located in the upper (San Lorenzo), intermediate (La Victoria) and lower (Puerto Mosquito) sections of the Gaira River. We found some differences in the gut contents and FFGs of the animals from different sites and between the climatic seasons. The dominant food source at all the sites and during both seasons was fine particulate organic matter (FPOM). At La Victoria, the generaLeptonema,SmicrideaandPhylloicus(all belonging to Trichoptera) presented significant differences in the consumption of coarse particulate organic matter (CPOM) between the rainy and dry seasons (p < 0.05). At San Lorenzo,Leptonemahad the highest animal tissue consumption value (p < 0.05). A discriminant function analysis based on gut contents suggested that some taxa may have been assigned to the wrong FFGs. We concluded that the diets of the aquatic arthropods in our study tended to present high trophic plasticity. Consequently, our results suggest that Neotropical rivers need to be re-evaluated in terms of traditionally established FFGs, which heretofore have been based on information from other regions of the world, producing incorrect assessments of aquatic systems.

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.

Effects of urbanization on habitat characteristics: what are the responses of habitat alteration on functional feeding groups of aquatic invertebrates?

A urbanização causa muitas alterações nas comunidades aquáticas. Sob ocupação urbana intensa, os rios sofrem as maiores modificações estruturais. O objetivo do trabalho foi avaliar os efeitos da urbanização nas características físicas e químicas do habitat e as respostas da urbanização nos grupos funcionais de alimentação (FFG) dos invertebrados. Parâmetros de qualidade da água (temperatura, condutividade, oxigênio dissolvido, pH, fósforo, clorofila-a, turbidez e matéria orgânica) e parâmetros do escoamento foram medidos em áreas pouco e altamente urbanizadas. Os FFG dos macroinvertebrados foram analisados e aplicados como substitutos de atributos do ecossistema. As diferenças na comunidade dos macroinvertebrados entre as áreas pouco e altamente urbanizadas foram avaliadas pelo escalonamento multidimensional não-métrico (nMDS) e pela análise de variância permutacional multivariada (Permanova). No nMDS foram observadas diferenças entre as áreas pouco e altamente urbanizadas. A Permanova mostrou diferença significativa entre os grupos do nMDS. As áreas pouco urbanizadas apresentaram maior riqueza em cada FFG, por outro lado, as áreas altamente urbanizadas apresentaram maiores valores de abundância de organismos coletores e predadores. Assim, a composição dos FFG respondeu às alterações no habitat que foram representadas pelos parâmetros de qualidade da água e do escoamento.

Macroinvertebrates of the Tributaries of Upper Baleh River, Sarawak

Studies on Baleh River with respect to aquatic fauna currently remains limited. Hence, this paper presents thespecies richness and composition of macroinvertebrates14 tributaries of Upper Baleh River in Kapit Division,Sarawak. A total of 1,154 individuals from 10 orders, 43 families and 66 genera of macroinvertebrates werecollected. The highest number of macroinvertebrate was taken from Naah River (201 individuals) and the leastfrom Ukit River (15 individuals). The order Ephemeroptera was the most abundant, with 45% of the totalindividuals caught, followed by Trichoptera (23%), Hemiptera (10%), and Coleoptera (9%). Three biologicalindices were used to measure the diversity of macroinvertebrate of which the values of the indices were low:Shannon diversity index (1.54–2.54), Shannon evenness index (0.33–0.89) and Margalef richness index (1.67–4.90). The composition of functional feeding groups varies between first and fourth order streams, which ispossibly an indication of ecological effects of siltation due to logging activities in the area.

River health assessment of the Yellow River source region, Qinghai-Tibetan Plateau, China, based on tolerance values of macroinvertebrates

For decades, the river health of the Yellow River source region (YRSR) on the Qinghai-Tibetan Plateau has been a focal issue owing to its unique geographic location and ecological functions. This study investigated the ecological status of the headwater streams, the main stem, and the tributaries of the Yellow River in the YRSR using the tolerance values of macroinvertebrates and those related to biotic indices. The macroinvertebrate assemblages of the headwater streams were characterized by lower biodiversity than the tributaries downstream, based on comparisons of taxonomical composition, functional feeding group composition, and the pollution-tolerant capacity of taxa. The headwater streams had a lower ratio (16%) of pollution-sensitive macroinvertebrate taxa than that of the tributaries downstream (30%). The biotic indices (family- and genus-level biotic indices) indicated that the ecological health of the headwater streams was comparably poorer than that of the downstream tributaries. The combined effect of vulnerable natural conditions and increasing human disturbance is likely the main cause of eco-environmental degradation in the Yellow River headwater streams.

Changes in benthic invertebrate communities of central Appalachian streams attributed to hemlock woody adelgid invasion

Eastern hemlock trees (Tsuga canadensis [L.] Carr.) often dominate riparian vegetation of central Appalachian headwater streams, and the invasive hemlock woolly adelgid (Adelges tsugae Annand; HWA) has decimated hemlock stands in this region. Although research concerning HWA impacts on soil, hydrology, and forest structure is emerging, associated changes in stream structure and function are not as well documented. We quantified HWA-invasion effects on benthic macroinvertebrate communities in 21 headwater streams across Ohio, West Virginia, and Virginia (USA) representing unimpacted, moderate invasion, and severe invasion, respectively. We observed differences in benthic macroinvertebrate community composition; severely invaded sites exhibited the highest diversity, whereas moderate sites had the lowest diversity. The composition of macroinvertebrate functional feeding groups exhibited shifts as well. For example, the relative abundance of herbivorous invertebrates increased from 4% (± 3%) at unimpacted sites to 23% (± 14%) at severely impacted sites. Changes in macroinvertebrate density, diversity, and functional-group composition were associated with sediment grainsize distribution (proportion bedrock and D84), large-wood characteristics (volume and density), and nutrient concentrations (PO4 and NH4). Our results suggest that in-stream physical and chemical alterations associated with HWA-invasion and subsequent hemlock decline are associated with changes in stream invertebrate diversity and trophic relationships. We demonstrate how a pervasive terrestrial invader can influence in-stream biotic communities.

Macroinvertebrate functional feeding group structure along an impacted tropical river: The Portoviejo River (Ecuador)

Performing biological assessments of freshwater systems is crucial in most tropical rivers as the lack of in-depth knowledge about functional diversity inhibits the design of appropriate water management and restoration plans. Therefore, in this paper, we investigated the presence and evolution of the functional diversity of the macroinvertebrate community along a tropical river. More specifically, 31 locations were sampled in the Portoviejo River (Ecuador) and identified macroinvertebrates were assigned to one of the following functional feeding groups (FFGs): shredders, collector-gatherers, collector-filterers, scraper-grazers and predators. Results show that high fluctuations and relatively low similarity in functional feeding group composition occurred among closely located sites, suggesting the presence of local disturbances. Locations close to the effluent of a wastewater treatment plant show an extreme dominance of scraper-grazers, suggesting elevated nutrient input and algae growth. Further downstream, the interaction of upstream disturbances and local land use influenced the community composition. These interactions and the confirmation of the importance of land use on aquatic communities underline the fact that management should include both taxonomic and functional diversity.

Leaf traits of Brazilian semiarid species as regulatory factors for associated aquatic invertebrates

The input of leaf litter is an important energy source for the riparian vegetation of aquatic ecosystems, and the chemical composition of leaf litter is decisive for colonization by invertebrates in streams. Plant species of the semiarid regions present different morphophysiological characteristics to combat the effects of drought, including tough leaves that have less nutritional quality. However, although concern regarding the decomposition of organic matter in aquatic ecosystems in semiarid regions is increasing, no information exists on the influence of leaf traits (e.g., N, C:N ratio and toughness) before the colonization of invertebrates and the decomposition of leaf litter. We hypothesized that: i) leaves with greater toughness, higher C:N ratio and lower amount of N present low density and biomass of associated invertebrates; ii) greater density and biomass of associated invertebrates results in increased decomposition rates; and iii) leaf traits influences the structure and composition of functional feeding groups of associated invertebrates. We incubated senescent leaves of Tabebuia aurea and Aspidosperma pyrifolium in a Brazilian semiarid stream using litter bags, and after 3, 7, 15 and 30 days, four litter bags were withdrawn for laboratory washing of the remaining leaf sediment and for collection of associated invertebrates. A. pyrifolium leaves presented higher nutritional quality (low C:N ratio, lower toughness), and the decomposition rate was higher than T. aurea leaves. Invertebrate density and biomass varied among litter, being higher in T. aurea and A. pyrifolium, respectively. The leaf litter quality also altered the composition of functional feeding groups. We observed a higher density of filters on T. aurea and collectors on A. pyrifolium. Both T. aurea and A. pyrifolium presented higher biomass of collectors, however T. aurea showed higher biomass of filters than A. pyrifolium. In the absence of shredders, leaf litter may have been used by invertebrates as a substrate, for shelter against predators and current, and sporadically as a food resource. Thus, differences in the leaf traits were important structures of the streams invertebrate. These are the first results of the influence of leaf traits on invertebrate colonization in the streams of semiarid regions, and reinforce the need for studies to verify the contribution of organic matter as well as the feeding preferences of invertebrates.

Relationship Between Macrophyte Communities and Macroinvertebrate Communities in an Urban Stream

The channelization has caused severe degradation of aquatic ecosystems during the past decades of rapid urbanization in metropolitan areas of China. The re-construction of the in-stream habitat of aquatic organisms and the restoration of aquatic ecosystems were more difficult in the urban stream than in the natural stream with the effluence of nutrient enrichment, water contamination, and in-stream habitat loss. Considering the ecological effects of the submerged macrophyte replantation on macroinvertebrate communities, one of the urban streams that used replantation restoration strategy was seasonally monitored from October 2012 to July 2013. There were four sampling sites, two located at the upper region and two in the middle region. Due to the relatively high levels of organic matter contamination, there are no sites in the downstream region of Qinghe River. Four types of submerged macrophyte were planted at each site to restore the in-stream habitat of two years ago, including Potamogeton pectinatus, Potamogeton crispus, Hydrilla verticillate, and Ceratophyllum demersum. Because of the unexpected development, Myriophyllum spicatum and Acorus calamus appeared at the upper reach of Qinghe River. Considering the average water depth of 30-40 cm, the revised Surber net with the enlarged net was used to collect macroinvertebrate samples. At each sampling site, three replicates of macroinvertebrates were carefully collected for each type of macrophyte. Three replicates were sampled for the comparison at the imperviously concrete sections of each site. The community composition of the macroinvertebrate was determined by cluster analysis and ordination analysis. The density, biodiversity, and community stability were higher in the sampling sections with the replantation of macrophyte than in impervious concrete sections. The occurrence of intermediate tolerant taxa such as Ephemera sp., Caenis sinensis Gui, Ecnomus sp., and Hydropsyche sp. indicated the recovery and restoration of macroinvertebrates in Qinghe River. However, the differences in the community structure, density, taxa richness, biodiversity index, and the composition of functional feeding groups of macroinvertebrates among different types of submerged macrophyte were not identified. Unlike providing extra habitats for macroinvertebrates in the vertical direction in natural streams and lakes, the submerged macrophyte provided more stable benthic habitats in urban streams. The stem and leaf of macrophytes could adjust the hydraulics and continually absorb, fix, and accumulate the suspended solids in the sediment and water interface. The root systems could stabilize the microhabitat of the sediment for macroinvertebrates, benthic algae, and microorganisms. Those aquatic organisms played an important role in the decomposition, transformation, and mineralization of nutrients and organic matter in urban streams. Following the recovery of stabilized microhabitats, community restoration and secondary succession of macroinvertebrates could continually and slowly happen. This study improved the understanding of the ecological effects of macrophytes on the restoration of aquatic organisms and ecosystems in urban streams.

Comparative Effects of Aquaculture and Water Level Fluctuations on Macroinvertebrate Communities in Three Gorges Reservoir, China

In this study, the comparative effects of the two disturbances (aquaculture and water level fluctuations) on macroinvertebrate communities were explored in two waterbodies connected with the reservoir system of Three Gorges Reservoir (TGR) in China. One water body called Gaoyang Bay which suffered organic pollution from intensive aquaculture. Another named Hanfeng Lake, where the effects of water-level fluctuations are obvious. The results showed that aquaculture could significantly affect the chemical forms of nutrients, decrease the α-diversity and increase the β-diversity of macroinvertebrates although the communities in the treatment area in Gaoyang Bay were not fundamentally changed comparing to the control area in the same bay. The densities of macroinvertebrates in the treatment area were significantly lower than that of the control area. The composition of functional feeding groups in the treatment area was close to that in Hanfeng Lake, but obviously different from that in the control area in Gaoyang Bay and the collectors and predators dominated the communities in this control area with the highest percentages. Although water-level fluctuations had negative effects on the communities by decreasing the α-diversity and increasing the β-diversity, which were confirmed by the values of Simpson index, Shannon-Wiener index and Harrison's index in the control area of Gaoyang bay and Hanfeng Lake, the adverse effects were relative low compared to aquaculture. In the bays of TGR, the small-scale disturbance (aquaculture activities) had more significant negative effects compared to the big-scale disturbance (water-level fluctuations related to dam operation of TGR).