Trophic Relationships Research Articles

Feeding patterns of the Neotropical cichlid, Australoheros acaroides (Hensel, 1870), in southern Brazil

ABSTRACT We present detailed data on the feeding patterns of the Neotropical cichlid Australoheros acaroides (Hensel, 1870) in southern Brazil, focusing on three questions: (i) do feeding patterns vary according to the season or body size class of the species? (ii) are the niche breadth and intraspecific trophic overlap influenced by the season or the body size class? and (iii) how do feeding strategies and the fractional trophic level vary among seasons and body size classes? We analyzed 88 individuals and identified 27 different types of food item. A PERMANOVA identified significant variation in the composition of the diet among the seasons and body size classes. We detected a relatively narrow trophic niche, and a feeding strategy that varied in the relative use of resources among seasons and body size classes. Trophic overlap was relatively discreet among seasons and body size classes, however, and there was also little variation in the fractional trophic position of the species among seasons or size classes. These findings provide important insights into different aspects of the trophic relationships of A. acaroides in the subtropical region of southern Brazil, and resolve an important knowledge gap in its feeding ecology.

Trophic relationship between mussels and scale worms under various seepage intensities in the haima cold seep: Insights from stable isotopes (δ13C and δ15N) and C:N:P stoichiometry

The deep-sea mussels Gigantidas haimaensis (Mytilidae: Bathymodiolinae) usually contain one scale worm Branchipolynoe pettiboneae in their mantle cavity in the Haima cold seep, South China Sea. To explore their environmental adaptation and coexistence mechanisms, the stable isotopes (δ13C and δ15N) and C:N:P ecological stoichiometry of G. haimaensis and the associated B. pettiboneae were investigated under different methane seepage intensities. In the presence of seepage, most mussels harbored one scale worm in their mantle cavity. However, under seepage cease, the physiological status of mussels looked unhealthy, and no scale worm appeared in their bodies. The variation in δ13C values was great among different mussel tissues, ranging from −49.7‰ to −57.8‰. The δ13C values of mussel tissues followed the order of foot > gill > mantle under active seepage, while no regular trend was found under seepage cease. The δ13C and δ15N of scale worms were averagely enriched by 2.9 ‰ and 3.2 ‰ relative to their mussel hosts, and the trophic niche separation between scale worms and mussels was more significant under active seepage. The δ13C value of mussel foot was significantly higher under active seepage (average −50.8‰) than under seepage cease (average −55.1‰), indicating that mussels might ingest and assimilate more 13C-rich suspended particulate organic matter (POM) under active seepage. In mantle tissues, the high C:N ratio and low δ13C value should be attributed to the high content of energy storage substances. The C:N ratio of mantle dramatically declined with the exhaustion of energy storage materials under seepage cease. The variation of P content was most significant in the gill, which might be regulated by the abundance of symbiotic bacteria. It can be speculated that the dramatic decline of P content in the gill was attributed to the loss of high-P bacterial symbionts under seepage cease. Both the C:P and N:P ratios of gill tissues significantly increased under seepage cease, which suggested the decline of food quality for scale worms. Mussel-dwelling scale worms might detect the change of food quality and abandon their starving mussel host. Our results help to better understand the environmental adaptation of chemoautotrophic mussels and scale worms under unstable seepage intensity in cold seep ecosystems.

Detection and Identification of Quarantine and Non-Quarantine Pest Species of Prunus avium Agroecosystem in Kyrgyzstan

Research of agroecosystem is a comprehensive study of one species with in biocenosis taking into account integrated plant protection to increase output. Gardeners in developing countries most often resort to the use of highly toxic universal pesticides, which leads to the Pesticide Syndrome with general decline of these products. The purpose of the research is to identify fauna of the cherry orchard in the south of Kyrgyzstan to apply eco-methods to control pest of stone fruits. Research objectives: 1) identification of organisms in the agrocenosis of the cherry orchard; 2) classification into biological groups; 3) comparison of the experimental and control fields. Our work was carried out in the autumn and spring periods on 2 experimental fields in the South of Kyrgyzstan for 2021-2022. The identified fauna species comprised of 26 species, which are: Coleoptera (26.9%) the largest order; followed by Lepidoptera and Equidoptera (Homoptera) (19.2%); and Hymenoptera (15.4%). The others are less than 10%: Diptera (7.7%); Acariformes; Hemiptera; Neuroptera (3.8%). At the same time, Coleoptera (26.9%) and Lepidoptera pests make up the bulk of the biomass of the agrocenosis of cherry orchard (19.2%) which dominants and most harmful. The research field no. 1 with annual pesticide load has 20% quarantine pest species with no zoophages among identified species. Whereas non-pesticide-treated field no. 2, no quarantine species, there is biocontrol and with richer biodiversity where trophic relationships is preserved.

Broad-scale perspective on body size-trophic position patterns of freshwater fishes at the intraspecific and community levels from individual-based data in China

As predators are generally larger than their prey, positive body size and trophic position relationships are typically assumed, and these relationships have helped in estimating and predicting the effects of global environmental change on the trophic dynamics of aquatic ecosystems. However, current efforts to confirm the generality of body size-trophic position relationships have focused mainly on interspecific patterns using species-aggregated and averaged data, and little effort has been devoted to assessing how trophic position scales with body size at the intraspecific and community levels as well as exploring its ecological drivers, particularly for fishes in freshwater ecosystems. To fill this gap, we present a broad-scale study of body size-trophic position relationships in freshwater ecosystems at both the intraspecific and community levels using an individual-based body size and isotopic signature dataset that includes 2564 samples of 65 fish species in China. Our results indicate that body size-trophic position patterns at both the intraspecific and community levels can be positive, negative or insignificant. Non-significant patterns predominated at both levels, with slightly more than 30 % showing positive relationships, which highlights that the positive body size-trophic position pattern is not universally prevalent and that body size should be used with caution as a proxy for the trophic position of fishes at both the intraspecific and community levels in freshwater ecosystems. No factor was related to body size-trophic position patterns at the community level, while habitat type, elevation, temperature and fishing pressure were identified as the key determinants of body size-trophic position patterns at the intraspecific level, implying that fishing and climate warming can shift the food-web size structure of freshwater ecosystems by affecting population trophic dynamics.

Microeukaryotes have unexpected importance in cold seep food webs through predation and parasitism

Cold seeps are inhabited by a high abundance of chemosynthetic prokaryotes and invertebrates. However, a complete food web between invertebrates and prokaryotes cannot be established without the important link of microeukaryotes. Yet, question such as which microeukaryotes are at work in cold seeps is still mostly open. We, therefore, compared the biological communities in cold seeps and adjacent areas of the South China Sea by the metabarcoding and quantitative PCR (qPCR) of nuclear 18S and 16S rRNA genes, and estimated the potentially ecological roles of microeukaryotes by cross-domain microbial network analysis. The anaerobic methane oxidizing archaea (ANME), sulfate-reducing bacteria (SRB) and Radiolaria accounted for most variations between microbial communities from the cold seeps and adjacent areas. A significant correlation was detected between the copy numbers of 18S rRNA gene and communities of the ANME and SRB in cold seeps, indicating close links between microeukaryotes and chemosynthetic prokaryotes. After adding microeukaryotic nodes microbial network became more complex, and the negative correlation proportion and average path length increased, suggesting increased predation and parasitism. The ANME and SRB groups were mainly negatively correlated with and potentially preyed by Acantharea and Cercozoa, which were then negatively correlated with annelids and mollusks. Parasitic microeukaryotes of Syndiniales widely existed in cold seeps and had close relationships with Polycystinea. Parasitism might cause the death of Polycystinea and the release of Syndiniales spores, which may be an important carbon source for the cold seep biota. Using Mantel analyses, we also demonstrated that trophic relationships are closer in cold seeps than in the adjacently deep-sea sediments, and that microeukaryote-metazoans linkages in cold seeps are closer than those between prokaryotes and metazoans. Overall, our study outlines the main components of food webs in cold seeps and highlights that microeukaryotes have an unexpected importance in the carbon cycle.

Amphibitic stoneflies (Plecoptera) are integrators of ecosystem processes in alluvial aquifers of gravel‐bed river floodplains

AbstractOver 50 years ago nymphs of the Plecoptera species, Paraperla frontalis Banks, 1906 (Plecoptera: Chloroperlidae), were shown to exist in a shallow floodplain aquifer of the Tobacco River, a gravel‐bed river in western Montana and later they were documented throughout the main stems of the Flathead River system. Nymphs are almost never found in surface waters, until they emerge on the river shorelines. As teneral adults, they mate and subsequently deposit fertilized eggs into the river. This novel life cycle is termed “amphibitic.” Over the years we and others have found P. wilsoni Ricker, 1965 (Plecoptera: Chloroperlidae), Kathroperla perdita Banks, 1920 (Plecoptera: Kathroperlidae), and five species of Isocapnia Banks, 1938 (Plecoptera: Capniidae), including long‐winged and brachypterous adults and wingless dwarfs (male and female), occupying amphibitic niches in the alluvial aquifers of rivers in Washington, Idaho, Colorado, Alaska and British Columbia. These stoneflies are remarkably tolerant of hypoxia which allows them to exist as abundant consumers in aquifer food webs subsidized by ancient methane. Indeed, stonefly tissues contain carbon that is up to 7000 years old, underscoring the existence of a strong interaction involving the uptake of labile carbon derived from methanogenic and methanotrophic process in aquifers. Details of life cycles, trophic relationships, distribution and abundance have been documented by a suite of studies on the Nyack Floodplain of the Middle Flathead River, Montana. In this paper we review the ecophysiology and ecology of these unique stoneflies in the context of their functional role in gravel‐bed river ecosystems.This article is categorized under: Water and Life > Nature of Freshwater Ecosystems Water and Life > Conservation, Management, and Awareness

Use of stable isotopes to reveal trophic relationships and transmission of a food-borne pathogen

Predators in food webs are valuable sentinel species for zoonotic and multi-host pathogens such as Toxoplasma gondii. This protozoan parasite is ubiquitous in warm-blooded vertebrates, and can have serious adverse effects in immunocompromised hosts and foetuses. In northern ecosystems, T. gondii is disproportionately prevalent in Inuit people and wildlife, in part due to multiple routes of transmission. We combined data on T. gondii infection in foxes from Nunavik (northern Québec, Canada) with stable isotope data tracking trophic relationships between foxes and several of their main prey species. Red (Vulpes vulpes) and Arctic fox (Vulpes lagopus) carcasses were collected by local trappers from 2015 to 2019. We used magnetic capture PCR to detect DNA of T. gondii in heart and brain tissues, and enzyme-linked immunosorbent assay to detect antibodies in blood. By linking infection status with diet composition, we showed that infected foxes had a higher probability of consuming aquatic prey and migratory geese, suggesting that these may be important sources of T. gondii transmission in the Arctic. This use of stable isotopes to reveal parasite transmission pathways can be applied more broadly to other foodborne pathogens, and provides evidence to assess and mitigate potential human and animal health risks associated with T. gondii in northern ecosystems.

Predicted shifts in suitable habitat of interacting benthic species in a warmer and invaded Canadian Arctic

Climate change and related expanding shipping activity are predicted to increase the risk of aquatic invasive species arriving in the Arctic. The goal of this study was to predict the distribution of an interconnected set of native and non-native primary producers and primary and secondary consumers in this changing context. Groups of species were selected to represent a benthic coastal Arctic food web in Hudson Bay, including kelps and eelgrass as primary producers (Alaria esculenta, Agarum clathratum, Saccharina latissima, Laminaria solidungula, and Zostera marina), amphipods as primary consumers (Gammarus oceanicus and G. setosus), and fish as secondary consumers (sculpins Gymnacanthus tricuspis, Myoxocephalus scorpius, M. scorpioides, and M. quadricornis). Ensemble models were used to predict the distribution of these native and several analogue non-native species (species known to be invasive elsewhere that can be considered analogues to Hudson Bay species): Dumontia contorta, Undaria pinnatifida, Sargassum muticum, and Codium fragile (primary producers); Gammarus tigrinus (primary consumer); and Artediellus atlanticus and A. uncinatus (secondary consumers). Predicted habitat suitability of trophic groups and analogue non-native species were overlaid under current and future climate change scenarios to assess areas of change through time. The predicted direction of potential distribution shifts varies by species identity (species composition) but not trophic group. Overall trophic relationships and roles in the ecosystem are likely to be maintained over time because while some species are predicted to decrease their potential ranges (e.g., M. quadricornis), others in the same trophic groups are predicted to increase (e.g., M. scorpius). Overlap (or lack thereof) between native and analogue non-native species pairs are expected to vary through time enabling novel interactions (e.g., competition) in space and time. This approach will help to identify current and future high-risk areas for trophic level changes and interactions with invasive species in response to global warming.

Projecting community trophic structures for the last 120 000 years

Studying past community dynamics can provide valuable insights for anticipating future changes in the world's biota. However, the existing fossil record is too sparse to enable continuous temporal reconstructions of wholesale community dynamics. In this study, we utilise machine learning to reconstruct Late Quaternary community structure, leveraging the climate–trophic structure relationship. We followed a four‐stage approach: 1) identify and map trophic structure units (TSUs) at the global scale based on the guild richness and composition of terrestrial mammal species weighing over 3 kg; 2) train a random forest classifier to predict the observed distribution of TSUs based on contemporary climatic conditions; 3) hindcast the global distribution of TSUs using climatic conditions as reconstructed over the past 120 000 years; and 4) compare TSU hindcasts against elements of community structure as estimated with the fossil record. Models project significant shifts in the geographical distribution of community trophic structures, with more pronounced changes occurring during the Pleistocene–Holocene transition. These shifts exhibit regional variations, particularly in Eurasia and North America, where the models project reductions in the distribution of less‐complex trophic structures over the last 24 000 years. Hindcasts partially identified the alterations in community structure seen in the fossil record, demonstrating a match between the observed and predicted times of change in mammal community structure (between 24 and 8 ka BP). However, projections of trophic guilds diverged from fossil records during the Holocene. While the fossil record indicated a decrease in the number of grazers and carnivores, our models projected an increase in these numbers. Characterising community‐wide responses to climatic changes is essential to address key questions about past and future impacts of such changes. Although further research is needed to refine the models, our approach offers a perspective for addressing the complex interactions among climate and trophic structures and model their distributions over time.

Food‐web energy fluxes, energy transfer efficiency, and diversity respond distinctively to pollution and water diversion in rivers

Abstract Water diversion and pollution are two pervasive stressors for river ecosystems that often co‐occur. The individual effects of both stressors on river communities and energy transfer across the food webs are well described; however, how they interact remains unknown. We hypothesised that low‐to‐moderate nutrient pollution gradient would cause a mild increase in invertebrate driven herbivory and water diversion a strong reduction in detritivory, whereas their joint effect would reduce invertebrate abundance and diversity, as well as total energy fluxes (from basal resources to invertebrates and fish). We also expected a shift in body size spectra slope with increased energy transfer between trophic levels with moderate pollution, but not with water diversion. To test these hypotheses, we selected four rivers across a range of nutrient pollution levels (a proxy of water quality) subject to similar water diversion schemes and compared food webs upstream and downstream of their diversion weirs. Both stressors changed the availability of basal food resources. Nutrient pollution induced changes in the green food web (i.e., biofilm‐based) by enhancing biofilm stocks, whereas water diversion affected the brown food web (i.e., detritus‐based) by decreasing stocks of detritus. The propagation of the effects to higher trophic levels differed with each stressor: pollution increased the homogeneity of community within the reach, whereas water diversion made communities more heterogeneous. Moreover, pollution induced changes within omnivores, increasing herbivory and carnivory, whereas diversion reduced the total energy fluxes through a decrease in detritivory, especially with pollution. Although most of the variables studied seemed to be more sensitive to water diversion, pollution often accentuated the response, being the interaction between both stressors more explanatory than any of the two stressors on its own. The effects of water diversion on diversity and energy flow through food webs are more detrimental to moderately polluted rivers than to systems with high quality water. We show that the use of tools merging knowledge on trophic relationships among species and their metabolic requirements enables disturbances to be detected that would otherwise go unnoticed.

Evaluation of the Effectiveness of Bone Grafting in Alveolar Ridge Augmentation Using the Two-Stage Splitting Technique.

Stimulation of neoosteogenesis is the main mechanism of osseointegration during installation of dental implants, bone tissue recession, and alveolar process augmentation in adentia. In experiments on miniature pigs, we used the technology of two-stage splitting of the ridge of the alveolar process of the mandible in combination with a xenograft that was placed between the fragments of the split bone plate. The morphology of the reparative process and the distribution of osteogenic differentiation markers in the compact and trabecular bone of the alveolar crest were studied. Signs of reparative osteogenesis were observed in the bone regenerate that had a lamellar structure, formed osteons, and foci of woven tissue. It was found that the xenograft was replaced by newly formed trabecular bone tissue. These sites were characterized by increased expression of osteocalcin and CD44. Augmentation technology through two-stage splitting provides trophic relationship of osteoprogenitor cells and is an effective method of osteogenesis stimulation in the alveolar process.

Scarcity of fixed carbon transfer in a model microbial phototroph-heterotroph interaction.

Although the green alga Chlamydomonas reinhardtii has long served as a reference organism, few studies have interrogated its role as a primary producer in microbial interactions. Here, we quantitatively investigated C. reinhardtii's capacity to support a heterotrophic microbe using the established coculture system with Mesorhizobium japonicum, a vitamin B12-producing α-proteobacterium. Using stable isotope probing and nanoscale secondary ion mass spectrometry (nanoSIMS), we tracked the flow of photosynthetic fixed carbon and consequent bacterial biomass synthesis under continuous and diurnal light with single-cell resolution. We found that more 13C fixed by the alga was taken up by bacterial cells under continuous light, invalidating the hypothesis that the alga's fermentative degradation of starch reserves during the night would boost M. japonicum heterotrophy. 15NH4 assimilation rates and changes in cell size revealed that M. japonicum cells reduced new biomass synthesis in coculture with the alga but continued to divide-a hallmark of nutrient limitation often referred to as reductive division. Despite this sign of starvation, the bacterium still synthesized vitamin B12 and supported the growth of a B12-dependent C. reinhardtii mutant. Finally, we showed that bacterial proliferation could be supported solely by the algal lysis that occurred in coculture, highlighting the role of necromass in carbon cycling. Collectively, these results reveal the scarcity of fixed carbon in this microbial trophic relationship (particularly under environmentally relevant light regimes), demonstrate B12 exchange even during bacterial starvation, and underscore the importance of quantitative approaches for assessing metabolic coupling in algal-bacterial interactions.

Fauna of sone groups of invertebrates of Erebuni State Reserve (Armenia

Aim. The aim of the work is to research the fauna of invertebrates in the Erebuni State Reserve. Material and Methods. As research material served invertebrates gathered in the Erebuni State Reserve. The work was carried out at the Scientific Centre for Zoology and Hydroecology, National Academy of Sciences, Republic of Armenia in the period 2019–2023. The material was from our own collections, as well as from collections of insects and mollusks of the Institute of Zoology. The identification and collection of insects and mollusks were done using standard methods. Results. An overview of some groups of invertebrates in the Erebuni State Reserve is here provided for the first time. As a result of the research, 35 species of Diptera, 15 species of Coleoptera, 44 species of Lepidoptera,10 species of aphids and 12 species of mollusks were identified. Some species are listed in the “Red Book” of Armenia and are under the protection of the state, and there are rare species and species found in the Republic of Armenia only in the reserve. 15 species of insects identified by us develop on 4 plant species included in the “Red Book” of Armenia. Conclusion. The Erebuni State Reserve is represented by a rather diverse and valuable fauna of invertebrates studied by us, including a number of rare and protected species. Species of invertebrates associated in their development with valuable wild, economically important and protected plants have been identified in the reserve. Identification of species diversity and trophic relationships of some groups of insects that develop on rare and protected plants of the reserve is relevant for natural areas under state protection, of which the Erebuni State Reserve is one.

Trophic relationships between protists and bacteria and fungi drive the biogeography of rhizosphere soil microbial community and impact plant physiological and ecological functions

Rhizosphere microorganisms play a vital role in enhancing plant health, productivity, and the accumulation of secondary metabolites. Currently, there is a limited understanding of the ecological processes that control the assembly of community. To address the role of microbial interactions in assembly and for functioning of the rhizosphere soil microbiota, we collected rhizosphere soil samples from Anisodus tanguticus on the Tibetan Plateau spanning 1500 kilometers, and sequenced the bacteria, fungi, archaea, and protist communities. We observed a significant but weak distance-decay relationship in the microbial communities of rhizosphere soil. Our comprehensive analysis of spatial, abiotic, and biotic factors showed that trophic relationships between protists and bacteria and fungi predominantly influenced the alpha and beta diversity of bacterial, fungal, and protistan communities, while abiotic factors had a greater impact on archaeal communities, including soil pH, available phosphorus, total phosphorus and mean annual temperature. Importantly, microbial interactions had a more significant influence on Anisodus tanguticus physiological and ecological functions compared to individual microorganisms. Network analyses revealed that bacteria occupy a central position of the co-occurrence network and play a crucial role of connector within this community. The addition of protists increased the stability of bacterial, fungal, and archaeal networks. Overall, our findings indicate that trophic relationships play an important role in assembly and for functioning of the rhizosphere soil microbiota. Bacterial communities serve as a crucial link between different kingdoms of microorganisms in the rhizosphere community. These findings help us to fully harness the beneficial functions of rhizosphere microorganisms for plants and achieve sustainable use of biological resources.

Garbage consumption by Arctic terrestrial predators in one of the most pristine land areas on Earth

Garbage may cause substantial environmental perturbations, in part because of its consumption by wildlife. Such consumption may have direct health implications for animals and may also influence trophic relationships. Even in pristine Arctic ecosystems, wildlife feeding in marine environments consume garbage in the form of plastic debris transported by ocean currents. We show that Arctic wildlife in pristine terrestrial environments may also ingest garbage or food items derived from abandoned camp sites. We found the remains of a chocolate wrapper and a milk powder bag in two Arctic fox (Vulpes lagopus) scats and a piece of cloth in an Arctic wolf (Canis lupus arctos) scat collected near Nares Strait, northern Greenland, one of the most pristine terrestrial wilderness regions on Earth. Found on Washington Land and associated with long-abandoned camp sites, these three scats were among 657 Arctic fox scats and 92 wolf scats collected as part of a larger study. Our study demonstrates that these two highly opportunistic predators managed to consume garbage despite the almost complete lack of human activity in this High-Arctic region. Our results highlight that abandoned anthropogenic material in the High Arctic may function as a source of garbage for local terrestrial wildlife over extended time periods, and that garbage consumption may become a potential issue if human activity in remote Arctic regions increases.

EUTROPHICATION OF THE KYIV RESERVOIR OF UKRAINE: REVIEW

It is known that the process of eutrophication in freshwater (especially in lakes and reservoirs) is increasing every day. That is why the relevance of this research is related to the existing processes of eutrophication in the Kyiv Reservoir of Ukraine. The research was conducted on the basis of laboratory research materials in 2021 year (before starting russian-Ukrainian war – 24.02.2022) and in 2023 year (after 600 days starting russian-Ukrainian war). The main aim of the research was to determine the main cause-and-effect relationships of strengthening eutrophication processes of the Kyiv Reservoir, which are currently available. It has been established that eutrophication of the Kyiv Reservoir occurs under natural and anthropogenic conditions. During the analysis (2021-2023 years), we identified the main causes of natural (transportation of nutrients due to floods, increased abrasion processes, climate change) and anthropogenic eutrophication (agricultural and urban activities, military activities). Analyzing the cause-and-effect relationships of the intensification of eutrophication processes, we emphasized the main consequences of the anthropogenic load on the water body of the reservoir for aquatic biota (change in trophic relationships in the aquatic ecosystem, reduction of aquatic biodiversity), for different branch of human activities (deterioration of the aesthetic value and water quality for water use, recreation and agriculture). Also, we highlighted the implications of eutrophication for the reservoir such as water toxicity that can influence the water bodies and biota (the appearance of cyanobacteria, which are harmful to biota and people).

Оңтүстік-Шығыс Қазақстанның ағаш жартылай қаттықанаттыларының (Hemiptera, Heteroptera) биологиясы мен экологиясы

As a result of the study of arboreal hemipterans of South-Eastern Kazakhstan, 35 species belonging to 8 genera were identified. Among them are the Miridae family (9 species), the Pentatomidae family (8 species), the Anthocoridae family (7 species), and 1-3 species are known from the remaining 5 families. According to the habitat, arboreal hemipterans are divided into dendrobionts (22 species), dendro-tamnobionts (2 species), dendro-tamno-hortobionts (4 species), dendro-hortobionts (6 species). Arboreal hemipterans are divided by trophic relationship into zoophages (14 species), zoophytophages (6 species), phytophages (12 species) and mycetophages (3 species). Arboreal hemipterans of South-East Kazakhstan are divided into 4 groups according to the number of generations they give per year: monovoltine (27 species), bivoltine (1 species), polyvoltine (4 species), acyclic (3 species). The species in the study area are ecologically mesophilic. In many species of Hemiptera, the wintering period takes place in the adult stage (20 species), the egg stage (10 species), the adult and larval stage (4 species), and the larval stage (1 species).

Fish trophic network in karst streams from Brazilian Pantanal headwaters

Abstract Trophic interactions have been a long-standing field of interest in ecology, helping to understand the relationships between organisms and how ecosystems function. In this study, we describe the trophic relationships of fish from karst environments in headwater streams of the upper Paraguai River basin. We analyzed the stomach contents of 81 fish species from the Serra da Bodoquena, calculated the metrics associated with the trophic network, incorporating the body size component in the analyses, and evaluated the participation of each species in network/module connectivity. The analyzed community trophic organization was based mainly on autochthonous items which were the most consumed items for about 30% of fish species. The trophic network showed a modular pattern without nestedness or specialization. However, nestedness was significant within each module, demonstrating a hierarchical compound topology (i.e., species with few connections interacted with subsets of the pairs of more connected species within each module). We also found a relationship between network connectivity and fish body size, in which small species tend to connect modules through generalist feeding strategies. Thus, we demonstrated a still little-known role of small species in fish trophic networks, and how trophic segregation occurs in a highly diverse community from Pantanal headwater streams.

Number of individuals, but not habitat complexity, influences the antipredator behavior of an Amazonian floodplain fish

Abstract Trophic relationships shape ecosystem structure by regulating energy flow and nutrient cycling, impacting prey consumption and prompting behavioral adaptations in prey species to mitigate risks. While much is known about fish antipredator behavior in marine environments, less is understood about these dynamics in freshwater environments. We investigated the antipredator behavior of an Amazonian floodplain fish, Crenuchus spilurus, across different habitat structural complexities. Through experiments, we examined how the number of individuals (1 and 4 individuals) and habitat structural complexity (low, medium, high, and very high) influence the fish response to predator presence. Small groups showed longer flight initiation distance (FID) than solitary individuals, suggesting a possible collective defense strategy against approaching predators. The structural complexity of the habitat did not have a direct effect on FID. Additionally, we noted variations in refuge usage by the fish across different habitat structural complexities. These findings underscore the interplay between behavioral and environmental factors in prey adaptation to predation risk in aquatic ecosystems.

Distribution and trophic relationships of the buffalo treehopper, Stictocephala bisonia, in the Samara region of Russia

Current climate change has led to an expansion of the ranges of many phytophagous species, an increase in the density of their populations, the number of generations and the intensity of plant damage. The purpose of this work was to assess the distribution and trophic relationships of the invasive buffalo treehopper Stictocephala bisonia Kopp et Yonke, 1977 (Insecta: Hemiptera: Membracidae) in the Samara region, as well as to determine the area of its distribution in the Russian Federation at the end of 2023. For the first time, adults of S. bisonia were recorded in Samara region in July 2009. Between 2011 and 2023, treehoppers were found in four Samara region districts. Totally, 116 leafhopper specimens were caught in 57 surveys. An average of 8.2 treehoppers were caught on herbaceous vegetation, and 6.0 specimens on tree species per 100 sweeps of the net. In the Samara region, in addition to forbs, the treehopper has been recorded on 24 plant species from 12 families. According to GBIF data, S. bisonia is distributed in 28 administrative Russian entities, the northernmost point is in the Nizhny Novgorod region (56.4N, 43.9E; 08/23/2023) and the easternmost point is in Bashkiria (51.9N, 58.2E; 07/29/2021). S. bisonia assumed to be a serious pest of young fruit trees and berry bushes.