Biotic Groups Research Articles

The aquatic plant communities of the Pilbara region of Western Australia: a region of arid zone wetland diversity

Context Decision making in conservation depends on robust biodiversity data. Well-designed systematic and rigorous surveys provide consistent and taxonomically broad datasets needed for conservation planning. This is important in areas such as the Pilbara of Western Australia with extensive mining and pastoralism. The collection of biodiversity data for aquatic plants represents a major contribution to assist in conservation planning and management of the region’s wetlands and rivers. Aims We documented the diversity and major patterns in the aquatic flora of Pilbara wetlands and rivers, to provide data to inform conservation planning and manage impacts of major land uses such as mining and pastoralism. Methods We undertook a systematic quadrat-based survey of the aquatic flora of 98 Pilbara wetlands and rivers. The full range of wetland types was sampled. Composition of charophytes and vascular aquatic plant communities were analysed against wetland permanence and water body type. Key results A diverse aquatic flora with several novel taxa was discovered. Charophytes were a major component of the aquatic flora. Floristic composition was strongly related to wetland type and water permanence with permanent sites showing higher richness. Less permanent sites captured a distinct component of the Pilbara aquatic flora. Conclusions The aquatic flora of the Pilbara represents a significant component of the region’s biodiversity. Patterning was concordant with previous studies of the riparian plant communities and aquatic invertebrates of the region providing synergies in reserve system design and management efforts. Implications High quality spatial biodiversity data particularly for poorly surveyed regions or biotic groups can provide major insights critical for effective conservation planning and management.

Marked Variability in Distance‐Decay Patterns Suggests Contrasting Dispersal Ability in Abyssal Taxa

ABSTRACTAimWe assess the role of spatial distance and depth difference in shaping beta diversity patterns across abyssal seascape regions. We measured the decrease of faunistic similarity across the northeast Pacific seafloor, to test whether species turnover rates differ between deep and shallow‐abyssal biogeographical provinces and whether these patterns vary across functionally or taxonomically different biotic groups.LocationAbyssal NE Pacific Ocean.Time PeriodPresent.Major Taxa StudiedBenthic Invertebrates (13 Phyla).MethodsWe examined the relationship between compositional similarity (𝛽sim) and spatial distance, distance‐decay, in benthic megafauna communities (animals > 10 mm) based on seabed imagery data (> 36,000 specimens in 402 species) collected across 28 abyssal seascape locations spanning a total of 4000 km. By comparing the statistical parameters (intercept and slope) of decay curves, we investigated whether distance‐decay patterns differ (i) between communities above and below the carbonate compensation depth (~4400 m at N Pacific), (ii) among taxa with contrasting life‐habits and (ii) across dominant phyla.ResultsWe found steeper species turnover rates in communities below 4400 m and variations in distance‐decay patterns across biotic groups. Turnover was higher for taxa facultatively growing on hard‐substratum patches (polymetallic nodules) than for sediment‐dwelling or swimming organisms. Cnidaria and Porifera, respectively, depicted the most and least evident spatial decays in community similarity.Main ConclusionsWe demonstrate the utility of combining seabed imaging with distance‐decay modelling to capture macroecological patterns in poorly explored deep‐sea ecosystems. Our results suggest that chemical boundaries associated with depth are a very relevant niche‐sorting mechanism driving large‐scale beta‐diversity patterns and an association between species life‐habits and dispersal limitation in abyssal seabed communities. These findings have important implications for biodiversity conservation plans in the deep ocean, amid the need to protect vast abyssal seascape ecosystems from globally rising human threats.

Method of estimating sea-surface paleotemperatures through biotic proxies: A case study in Upper Paleozoic paleoclimatic, paleogeographic and paleotectonic reconstructions of Siberia.

This study introduces a novel approach for quantitatively assessing sea-surface paleotemperatures examined in the Upper Paleozoic of Siberia, utilizing the obtained in the region data as a case study of the use of this method. The method relies on evaluating the taxonomic composition and ecological proxies of biota. It utilizes a comprehensive dataset encompassing the geographic distribution and ecology of various biotic groups in Siberia and adjacent regions, leveraging the newly developed by the authors large PaleoSib database and partially the Paleobiology Database (paleobiology.org) The taxonomy has been used according to the database of Global Biodiversity Information Facility (gbif.org). Fossils collected from individual locations often exhibit a wide spectrum of paleotemperatures. To address this variability, we developed an algorithm for calculating average biotic paleotemperatures in each locality/time slice. Our computations of the available data have unveiled a coherent pattern of paleoclimate dynamics, particularly Sea Surface Temperature, across Siberian basins and surrounding areas during the Late Paleozoic era. These findings significantly contribute to a refined comprehension of paleoclimate and paleotectonic dynamics in the region during that specific time. To enhance paleotemperature analyses, we have integrated lithological indices with biotic ones, fortifying the overall methodology and furnishing a more robust framework for interpreting paleoclimate data. The method could be a helpful tool in regional and interregional studies, regardless of the utilized rock's age and fossil groups.

Effects of Ammonia Concentration on Sperm Vitality, Motility Rates, and Morphology in Three Marine Bivalve Species: A Comparative Study of the Noble Scallop Mimachlamys nobilis, Chinese Pearl Oyster Pinctada fucata martensii, and Small Rock Oyster Saccostrea mordax.

Ammonium (NH4+) plays a crucial role in the reproductive processes of key biotic groups in aquatic ecosystems-bivalves. This study aims to elucidate the effects of three different ammonium ion concentrations on sperm vitality, swimming kinematics, and morphology of Mimachlamys nobilis, Pinctada fucata martensii, and Saccostrea mordax. The results indicate that the sperm vitality and motility rates of M.nobilis and S. mordax are inversely proportional to the ammonium concentration, especially in the treatment group with an ammonium concentration of 3 mmol/L, where the decrease in sperm vitality and motility is most significant. In contrast, the sperm of P. fucata martensii reacted differently to increasing ammonium concentrations. After the addition of 2 mmol/L of ammonium, the sperm vitality and motility of P. fucata martensii reached a peak, showing a significant stimulatory effect. Additionally, as the ammonium concentration increased, the curling of the sperm flagella in M.nobilis and S. mordax increased. However, sperm flagella curling in P. fucata martensii showed no change compared to the control group. This study provides insights into the effects of ammonium concentrations on the sperm vitality and motility of three marine bivalve species and highlights the importance of sperm flagella curling as a factor affecting sperm.

Homogeneous selection and stochasticity overrule heterogeneous selection across biotic taxa and ecosystems

Deterministic factors including homogeneous and heterogeneous selection and stochastic factors jointly shape ecological communities. However, a quantitative synthesis of the factors underlying the balance among different assembly processes is lacking. Here, we synthesized data from 149 datasets covering major biotic groups and ecosystem types globally. We used a null model approach based on Raup–Crick dissimilarities and Bayesian meta‐regression to analyze the data. We found that communities were more under homogeneous selection than heterogeneous selection across biotic taxa and ecosystems. Environment selected species homogeneously more often at small scales while heterogeneously more often at large scales. Stochasticity also showed scale‐dependence as stochastic community assembly increased with study scale. Homogeneous and heterogeneous selection were strongest at high latitudes while stochastic factors were strongest in tropics. Marine systems had the highest degree of homogeneous selection and the lowest stochasticity. We provide the first analysis of community assembly across taxa and ecosystems which should be important for a better understanding of how communities respond to environmental change.

Insights on long-term ecosystem changes from stable isotopes in historical squid beaks

BackgroundAssessing the historical dynamics of key food web components is crucial to understand how climate change impacts the structure of Arctic marine ecosystems. Most retrospective stable isotopic studies to date assessed potential ecosystem shifts in the Arctic using vertebrate top predators and filter-feeding invertebrates as proxies. However, due to long life histories and specific ecologies, ecosystem shifts are not always detectable when using these taxa. Moreover, there are currently no retrospective stable isotopic studies on various other ecological and taxonomic groups of Arctic biota. To test whether climate-driven shifts in marine ecosystems are reflected in the ecology of short-living mesopredators, ontogenetic changes in stable isotope signatures in chitinous hard body structures were analysed in two abundant squids (Gonatus fabricii and Todarodes sagittatus) from the low latitude Arctic and adjacent waters, collected between 1844 and 2023.ResultsWe detected a temporal increase in diet and habitat-use generalism (= opportunistic choice rather than specialization), trophic position and niche width in G. fabricii from the low latitude Arctic waters. These shifts in trophic ecology matched with the Atlantification of the Arctic ecosystems, which includes increased generalization of food webs and higher primary production, and the influx of boreal species from the North Atlantic as a result of climate change. The Atlantification is especially marked since the late 1990s/early 2000s. The temporal patterns we found in G. fabricii’s trophic ecology were largely unreported in previous Arctic retrospective isotopic ecology studies. Accordingly, T. sagittatus that occur nowadays in the high latitude North Atlantic have a more generalist diet than in the XIXth century.ConclusionsOur results suggest that abundant opportunistic mesopredators with short life cycles (such as squids) are good candidates for retrospective ecology studies in the marine ecosystems, and to identify ecosystem shifts driven by climate change. Enhanced generalization of Arctic food webs is reflected in increased diet generalism and niche width in squids, while increased abundance of boreal piscivorous fishes is reflected in squids’ increased trophic position. These findings support opportunism and adaptability in squids, which renders them as potential winners of short-term shifts in Arctic ecosystems.

A cumulative impact assessment on the marine capacity to supply ecosystem services

Ecosystem services link the status of biodiversity and its functioning to societal goods and benefits contributing to human wellbeing. As such, they can play a key role in preserving the environment and managing natural resources and ecosystems to conserve nature's contributions to people. Identification of the main threats acting on the natural environment, and how these may impact its capacity to supply ecosystem services, is fundamental to the maintenance of these services. To that end, we present a novel approach based on a cumulative impacts assessment that 1) covers all relevant human activities and their pressures, 2) links impacts to the biotic groups that make up biodiversity and 3) provides an estimation of the Service Supply Potential based on the functioning of these biotic groups. Key proxy metrics to estimate this Service Supply Potential were identified from a literature review and quantified using a food web model (Ecopath with Ecosim). In addition to this quantitative information, the assessment of the capacity to supply ecosystem services was supplemented with expert judgement-based information to reflect the societal preferences that drive the allocation of human capital and turn these services into societal goods and benefits. As a proof of concept, the method was applied to the North Sea ecosystem. Results showed that, overall, the capacity of the North Sea to supply Cultural ecosystem services was most threatened, with an average potential decline of 50 % compared to an undisturbed situation. This was followed by the Provisioning ecosystem services with 46 % and the Regulation & Maintenance with 38 %. The main anthropogenic threats (excluding climate change) to the North Sea capacity to supply ecosystem services come primarily from fishing contributing to 51 % of the overall threat. Of the remaining 18 sectoral activities another 23 % was contributed by mining, non-renewable energy, tourism, and agriculture.

Paleoecological and paleobiogeographic implications of a seagrass-indicating foralgal skeletal assemblage: Retracing the Burdigalian Quilon Limestone (Kerala Basin, SW India)

Seagrasses are marine angiosperms documented in shallow-marine, soft bottom settings across the Cenozoic. They proliferated globally after their divergence from other alismatid monocots in the late Cretaceous followed by an adaptation to the marine environment. Detailed evaluation of seagrasses in the geological archives is of utmost importance to understand their responses to climatic and environmental alterations in the deep time perspective. Here we examine the lower Miocene Quilon Limestone from the Kerala Basin (southwest India) that encompasses a Pseudotaberina-Halimeda floatstone signalling a robust photozoan foralgal skeletal assemblage. This is characterized by the dominant soritid foraminifer Pseudotaberina and the calcareous green alga Halimeda, in association with other foraminifera and representatives from various biotic groups that indicate a tropical seagrass paleoenvironment. Abundant soritids together with various bryopsidalean Halimeda species indicate light and temperature as the major ecological drivers regulating the Quilon Limestone seagrass paleocommunity during the early Miocene (Burdigalian). The spatio-temporal distribution patterns of Halimeda also indicate temperature as the most prominent ecological constraint determining its dispersal and evolution at multiple latitudes. A well illuminated substrate is envisaged to support the development and calcification of the Halimeda thalli. Abundance of K-strategist foraminifera with minor occurrence of suspension-feeding bryozoans and some gastropods, bivalves indicate a low-nutrient environment.

Lower miocene stratigraphy of the Eastern Paratethys: Problems and state of the art

The Lower Miocene regional stages of the Eastern Paratethys, the Caucasian, Sakaraulian, and Kozakhurian, have been recognized in different structural facies zones of the basin and have no reliable universal stratigraphic basis for defining their boundaries and volume. Mollusks, benthic and planktonic foraminifers, calcareous nannoplankton, and dinocysts have been studied in a number of Lower Miocene sections in stratotype areas of the Central Ciscaucasia and Kartli Depression in Georgia. The fossil biota groups of the Caucasian, Sakaraulian, and Kozakhurian sediments are briefly characterized. The available new data on the phytoplankton of these regional stratigraphic units as well as the records of the benthos composition in the marginal facies of the Ciscaucasian Basin allow a comparison between the stratotype regions and show possibilities for a more detailed correlation among them.

Asynchronous multitrophic level regime shifts show resilience to lake browning

Lake browning is widespread due to increased supply of dissolved organic carbon under climate warming and nitrogen deposition. However, multitrophic level responses to lake browning are poorly understood. Our study aims to explore such responses across multitrophic levels based on sedimentary records of diatoms, chrysophyte stomatocysts and chironomids in a remote headwater lake in the Three Gorges Reservoir region, central China. Although all biotic proxies were analysed in the same core, the timing of shifts in chironomids (1886 ± 18 CE) preceded that in chrysophyte stomatocysts (∼1914 ± 10 CE) and diatoms (∼1941 ± 6 CE). Shifts in biotic communities were closely linked to rising temperature, δ15N depletion (a proxy for nitrogen deposition), δ13C enrichment (a proxy for littoral moss expansion), as well as biotic interactions, whereas the relative importance of the driving forces varied among the three biotic groups. Our results suggest that the zoobenthos grazing effect might be more important than bottom-up pathways in humic environments. Additionally, the coexistence of benthic, littoral and pelagic algae after the 1950s suggested that mixotrophic chrysophytes could reduce lake browning through heterotrophic processes and sustain the ecological equilibrium between littoral, pelagic and benthic productivity. Therefore, lake browning ecosystem regime shifts require analyses of multiple trophic levels. Our results suggest that heterotrophy may become more important in lake ecosystem carbon cycling with water brownification in Mulong Lake, as well as similar montane lakes.

THE MIDDLE EOCENE CLIMATIC OPTIMUM (MECO) IMPACT ON THE BENTHIC AND PLANKTIC FORAMINIFERAL RESILIENCE FROM A SHALLOW-WATER SEDIMENTARY RECORD

We present here new quantitative analyses of planktic and benthic foraminifera to assess the impact of the Middle Eocene Climatic Optimum (MECO, ~40 Ma) on these biotic groups studied along a shallow-water succession rich in larger benthic foraminifera (Sealza, Liguria, NW Italy). The MECO is one of the major Eocene global warming events, characterized by ~4–6°C warming, shifts in the global carbon cycle, and rise in atmospheric pCO2. The Sealza succession is interpreted as the product of a drowning ramp influenced by tectonic activity and provides an exceptional chance to compare biotic variations in shallow-water assemblages with deep-water communities across the MECO. In the section, the MECO interval is tentatively constrained by stable isotope oxygen data and calcareous plankton biostratigraphy. The marked decline in abundance of the epifaunal benthic Cibicidoides across the lower-middle part of the MECO suggests a decrease in oxygenation at the seafloor. Further evidence of oxygen depletion is the increase in organic matter content (TOC) of the sediment and the presence of infaunal genera Uvigerina and Bolivina. The planktic foraminiferal assemblages record the MECO warming in the upper water column as the mixed-layer warm index genera Acarinina and Morozovelloides markedly increase in abundance. In the post-MECO interval, here poorly exposed, cooler conditions are indicated by the dominance of the cold-water index genus Subbotina. Remarkably, Acarinina decline in abundance in the upper MECO interval and never recover. The MECO perturbance permanently impacted the benthic and planktic communities at Sealza that exceeded the tipping point to move to a new regime, thus proving the fauna to be not resilient, but also not recording any extinctions.

Rise and fall of a continental mesic radiation in Australia: spine evolution, biogeography, and diversification of Cryptandra (Rhamnaceae: Pomaderreae)

Abstract The Australian continent has experienced progressive aridification since the Miocene, spurring recent radiations of arid-adapted lineages and the likely decline of mesic biotic groups. While examples of the former have been relatively well-documented, post-Miocene declines of non-arid sclerophyllous floras are less well understood. Here, we present a well-sampled time-calibrated nuclear phylogeny (140 accessions representing 60/65 species) of an Australian plant genus (Cryptandra Sm.: Rhamnaceae) and using ancestral range reconstructions and diversification analyses, elucidate its evolutionary history through space and time. We used high-throughput sequencing to recover 30 orthologous nuclear loci and BioGeoBEARS to infer ancestral areas. We show that the present-day distribution of Cryptandra can be explained by multiple vicariance events followed by in situ diversification with little exchange between regions. All diversification models show a speciation rate decline in Cryptandra after its radiation in the Miocene (c. 23 Mya). This coincides with aridification episodes across Australia and indicates that diversification of this genus has been negatively affected by the expansion of aridity. We also show that there were no significant differences in diversification rates between spinescent and non-spinescent Cryptandra lineages, suggesting that spinescent lineages may be the legacies of selection from extinct megaherbivores.

Degree of urbanization and vegetation type shape soil biodiversity in city parks

Urbanization negatively impacts aboveground biodiversity, such as bird and insect communities. City parks can reduce these negative impacts by providing important habitat. However, it remains poorly understood how the degree of urbanization and vegetation types within city parks (e.g., lawns, woodland) impact soil biodiversity. Here we investigated the impact of the degree of urbanization (urban vs. suburban) and vegetation type (lawn, shrub-lawn, tree-lawn and tree-shrub mixtures) on soil biodiversity in parkland systems. We used eDNA metabarcoding to characterize soil biodiversity of bacteria, fungi, protists, nematodes, meso- and macrofauna across park vegetation types in urban and suburban regions in Xiamen, China. We observed a strong effect of the degree of urbanization on the richness of different soil biota groups, with higher species richness of protists and meso/macrofauna in urban compared to suburban areas, while the richness of bacteria and fungi did not differ, and the difference of nematode richness depended on vegetation type. At the functional level, increased degree of urbanization associated with greater species richness of bacterivores, plant pathogens and animal parasites. These urbanization effects were at least partly modulated by higher soil phosphorous levels in urban compared to suburban sites. Also, the vegetation type impacted soil biodiversity, particularly fungal richness, with the richness of pathogenic and saprotrophic fungi increasing from lawn to tree-shrub mixtures. Tree-shrub mixtures also had the highest connectedness between biotas and lowest variation in the soil community structure. Overall, we show that soil biodiversity is strongly linked to the degree of urbanization, with overall richness increasing with urbanization, especially in bacterivores, plant pathogens and animal parasites. Targeted management of vegetation types in urban areas should provide a useful way to help mitigate the negative effect of urbanization on soil biodiversity.

Response of macroinvertebrate and epilithic diatom communities to pollution gradients in Ecuadorian Andean rivers

Population growth and increasing production demands threaten the highly diverse Andean freshwater ecosystems. Biological indicators constitute a valuable tool for evaluating the ecological quality of freshwater ecosystems under different pressures. Diatom and macroinvertebrate assemblages are the most used bioindicators to assess water pollution, whereby these biotic groups occupy the first and second trophic levels and respond to habitat pollution. Several studies have explored the response of these communities to water pollution in other regions, but no studies have examined their performance in Andean rivers. In this context, this research aimed to evaluate the responses and relationships of both groups of bioindicators in the Upper Guayllabamba basin. We collected macroinvertebrate and diatom samples from nine sites in this basin during the dry and wet seasons, calculated trophic indices for both groups, and related them to environmental characteristics. The results indicated that both bioindicators were sensitive to changes in land use and nutrients. Epilithic diatoms were more sensitive to changes in water chemistry and macroinvertebrates to changes in fluvial habitat and land use. The index based on macroinvertebrates better-detected changes in quality classes between sites and seasons. Therefore, both indices gave complementary information, and their joint use seems suitable in Andean streams.

Recovery and reservation in the formation of ecosystem reliability

Reliability is one of the main characteristics of ecosystem, its ability to effectively maintain its structure and perform functions without fail when environmental conditions change due to natural or anthropogenic negative impacts. It is shown that in the assessment of ecosystems, the leading role belongs to environmental monitoring to determine the condition of ecosystem components and identify the possibility of ensuring reliability. Methodical approaches to environmental monitoring have been developed. Mechanisms of ensuring and principles of reliability assessment of different types of ecosystems are considered. The main attention is paid to the recovery, reservation and conditioning of ecosystems under the influence of negative factors. To quantify the ability of ecosystems to recover, it is proposed to use appropriate criteria, which are determined by certain calculation formulas. With insufficient reliability of ecosystem elements due to the actions of negative factors, its reliability is ensured by reservation at the expense of additional means and capabilities. In the case of agroecosystems, which are artificially created biotic groups of organisms that are supported by humans, it is an integrated approach using the theory of ecosystem reliability that expands the range of means to study their effective functioning. It is noted that the increase in the reliability of the agroecosystem is provided by the use of its reliable elements, as well as special systems for ensuring recovery and reservation. It is emphasized that the application of reliability theory in the study of agroecosystems contributes to the management of their functional efficiency for obtaining environmentally safe products

What do macroinvertebrate indices measure? Stressor-specific stream macroinvertebrate indices can be confounded by other stressors.

Monitoring programmes worldwide use biota to assess the "health" of water bodies. Indices based on biota are used to describe the change in status of sites over time, to identify progress against management targets and to diagnose the causes of biological degradation. A variety of numerical stressor-specific biotic indices have been developed based on the response of biota to differences in stressors among sites. Yet, it is not clear how variation in pressures within sites, over what time period, and in what combination has the greatest impact on different biotic groups. An understanding of how temporal variation in pressures influences biological assessment indices would assist in setting achievable targets and help focus catchment-scale mitigation strategies to ensure that they deliver the desired improvements in biological condition.Hydrochemical data provided by a network of high-frequency (15 or 30 min) automated monitoring stations over 3 years were matched to replicated biological data to understand the influence of spatio-temporal variation in pollution pressures on biological indices. Hydrochemical data were summarised in various ways to reflect central tendency, peaks, troughs and variation over 1-90 days before the collection of each biological sample. An objective model selection procedure was used to determine which hydrochemical determinand, and over what time period, best explained variation in the biological indices.Stressor-specific indices derived from macroinvertebrates which purportedly assess stress from low flows, excess fine sediment, nutrient enrichment, pesticides and organic pollution were significantly inter-correlated and reflected periods of low oxygen concentration, even though only one index (ASPTWHPT, average score per taxon) was designed for this purpose. Changes in community composition resulting from one stressor frequently lead to confounding effects on stressor-specific indices.Variation in ASPTWHPT was best described by dissolved oxygen calculated as Q5 over 10 days, suggesting that low oxygen events had most influence over this period. Longer-term effects were apparent, but were masked by recovery. Macroinvertebrate abundance was best described by Q95 of stream velocity over 60 days, suggesting a slower recovery in numbers than in the community trait reflected by ASPTWHPT.Although use of ASPTWHPT was supported, we recommend that additional independent evidence should be used to corroborate any conclusions regarding the causes of degradation drawn from the other stressor-specific indices. The use of such stressor-specific indices alone risks the mistargeting of management strategies if the putative stressor-index approach is taken to be more reliable than the results herein suggest.

Probing river health status: a study based on index of biotic integrity (IBI) in Tapti River of Deccan plateau, India.

Anthropogenic activities impacted the ecological health of rivers by altering the physical habitat and water flow as well as by pollution. Monitoring of biotic groups for gauging the river health is a prerequisite for assessing the extent of degradation and formulating management guidelines for river restoration. An assessment using fish-based index of biotic integrity (IBI) was carried out in the Central Indian river, Tapti, for probing its health status. For the multimetric index, twelvemetrics were adopted under five categories: taxonomic richness, habitat composition, tolerance indicators, species resilience, and trophic composition. Among the studied sites, Betul in the upper stretch was selected as the reference site for River Tapti, which almost meets the upper expectation of the metrics explored. Continuous scoring method was applied to evaluate the biotic integrity in the selected sites of the river. The IBI score based on the pooled fish abundance data in River Tapti ranged from 33 to 60. Assessment of the ecological health revealed that three-fourth of the river stretch was moderately impaired (25-50% of impairment) and the most deteriorated site was Kamrej with 45% of impairment which might be due to its location in the urban area with high influx of domestic sewage and industrial effluents. The IBI scores were plotted and compared with an independent estimate of water quality. The CCA with environmental and IBI variables revealed higher correlation with each other and the functional groups such as carnivores, herbivores, and fishes with high population doubling time (PDT) were found in close association with nitrate-N, total alkalinity, and specific conductivity. The study urges the need for the adoption of proper management and mitigation measures to restore the health and wealth of aquatic ecosystem.

Ocean warming and CO2-driven acidification can alter the toxicity of metal-contaminated sediments to the meiofauna community

Interactive effects of trace metal contamination, ocean warming, and CO2-driven acidification on the structure of a meiofaunal benthic community was assessed. Meiofauna microcosm bioassays were carried out in controlled conditions in a full factorial experimental design which included three fixed factors: metal contamination in the sediment (3 levels of a mixture of Cu, Pb, Zn, and Hg), temperature (26 and 28 °C) and pH (7.6 and 8.1). Metal contamination caused a sharp decrease in the densities of the most abundant meiobenthic groups and interacted with temperature rise, exacerbating deleterious effects for Nematoda and Copepoda, but mitigating effects for Acoelomorpha. CO2-driven acidification resulted in increased acoelomorphs density, but only in sediments with lower levels of metals. Copepod densities, in turn, were lower in the CO2-driven acidification scenario regardless of contamination or temperature. The results obtained in the present study showed that temperature rise and CO2-driven acidification of coastal ocean waters, at environmentally relevant levels, interacts with trace metals in marine sediments, differently affecting the major groups of benthic biota.

Dissecting biodiversity: assessing the taxonomic, functional and phylogenetic structure of an insect metacommunity in a river network using morphological and metabarcoding data

Most empirical metacommunity studies rely solely on morphological identification of taxa, precluding the species-level identification of several biotic groups, which can influence the characterization of metacommunities. DNA metabarcoding enables inference of species and even intraspecific diversity from community samples but has rarely been used to infer metacommunity structure. Here, we combined morphology and metabarcoding to improve the characterization of an insect metacommunity at different identification levels. We included measures of taxonomic, functional and phylogenetic richness, and we evaluated drivers affecting metacommunity structure (i.e., environmental filtering and dispersal). Communities were sampled from an area that included nine perennial, two near-perennial and two intermittent sites in a river network characterized by high hydrological variability. We identified organisms to a mixed (family to species) taxonomic level using morphology, and to operational taxonomic unit (OTU) and haplotype levels using metabarcoding of the mitochondrial cytochrome c oxidase gene. Diptera and Ephemeroptera showed the greatest increases in taxonomic and phylogenetic richness but not biological trait richness with increasing taxonomic resolution. The joint effect of environmental filtering and dispersal was more important than their individual effects in shaping metacommunity structure at all identification levels. Mixed-level and OTU-level identification were more effective than family and haplotype in characterizing the drivers of metacommunity structure. We demonstrate that the greater taxonomic resolution enabled by metabarcoding could improve understanding of metacommunities within river networks, thus enhancing our capacity to predict ecological responses in ecosystems adapting to global change.

Региональные особенности формирования пирологических обстановок в степях Cеверной Eвразии на основе данных FIRMS

Grass fires are characteristic of the vast region of Northern Eurasia, covering the landscapes of the steppes and adjacent natural areas. The study of the spatio-temporal heterogeneity of fires makes it possible to identify and evaluate the leading factors of the occurrence and spread of fires. Pyrological research is of particular relevance due to the negative impact on various groups of steppe biota and the quality of the environment, the lack of an objective understanding of the causes of the high variability of fire development indicators. The main objective of the study was to identify regional features of the formation of pyrologic environments in the long-term and intraannual aspects. The global archive of thermal anomalies MCD14ML (FIRMS) was adopted as the main source of fire data and the analyzed parameter itself. It is revealed that a specific feature of the FIRMS data archive is the possibility of fixing active fires on arable land, which is almost impossible to carry out directly from satellite images. In this regard, the greatest density of thermal anomalies is observed in the agriculturally developed provinces (western sectors of the steppes and adjacent territories), for which the practice of agricultural bollards remains a traditional way of farming. A comparison of the long-term dynamics of fires in arable land and pasture-hayfields shows a close relationship. Similar results were obtained during the analysis of the intra-annual (daily) distribution of thermal anomalies, the peaks of which occur at the beginning and the period of completion of agricultural work. This serves as indirect evidence that uncontrolled agricultural fires are the cause of a significant part of steppe fires. Regional pyrological conditions in the steppes of Northern Eurasia and adjacent territories have similar features in long-term dynamics and reflect the complex nature of the interaction between natural and anthropogenic factors. Understanding current trends in the development of fires can contribute to solving the problems of managing fire-hazardous situations.