River Community Research Articles

Composition and distribution of hyporheic and macrobenthic fauna in a Neotropical mountain river, Colombia

This study examined the composition and diversity of the invertebrate communities that inhabit the hyporheic zone (HZ) in the upper and lower basins of the Dagua River, a tropical mountain stream, and their relationship with the macrobenthic fauna. In the HZ, different taxa were collected, many of which have been reported in several regions worldwide, suggesting that the biodiversity of the hyporheic community in Colombian rivers may be high. Although the hyporheic and macrobenthic fauna shared a moderate percentage (> 50 %) of taxa, their ecological structures were different. The analysis of hyporheic filtrate water showed the presence of microplastic (MP) fibers as well as fauna, a condition that, based on the literature review, could represent a risk for the normal functioning of this river ecosystem.

Benthic Macroinvertebrate Communities in Wadeable Rivers and Streams of Lao PDR as a Useful Tool for Biomonitoring Water Quality: A Multimetric Index Approach

Lao PDR, a landlocked country in the lower Mekong River basin of Southeast Asia, has been considered a global biodiversity hotspot with a high level of biological endemism. In recent years, urban development and industrialization have affected the water quality of freshwater ecosystems in Lao PDR. However, the assessment of water quality in the country is primarily focused on a physicochemical method, while the application of a multimetric index (MMI) approach using benthic macroinvertebrates for biomonitoring in rivers and streams has not been established. MMI, based on benthic macroinvertebrates, is a biomonitoring tool that considers the effects of multiple anthropogenic impacts on benthic macroinvertebrate metrics associated with their biological attributes (e.g., taxa richness, composition, pollution tolerance, habits, and functional feeding) and aggregates individual metrics into a single value for assessing the water quality and health conditions of aquatic ecosystems. Here, we developed an MMI based on macroinvertebrate communities collected during 2016–2018 from 10 localities of streams and wadeable rivers in Lao PDR. Of the 54 potential metrics tested, 35 candidate macroinvertebrate metrics representing richness, composition, trophic structure, habit, and tolerance to pollution were selected, while 19 metrics were excluded. Of the 35-candidate metrics, a total of 11 core metrics (Total taxa, EPT taxa, Ephemeroptera taxa, %Diptera, %Plecoptera, %Tolerant, Beck’s biotic index, %Intolerant, Filterers taxa, %Sprawlers, and %Burrowers) were finally selected for the development of MMI based on their sensitivity, redundancy, and easy-to-apply tool for the biomonitoring program. These metrics can be used to distinguish the reference (seven sites) from stressed conditions (seven sites). In addition, the final MMI scores classified 40 sampling sites into four classes of water quality, including excellent (25%), good (10%), fair (60%), and poor (5%), which the conventional physicochemical method could not clearly distinguish. The Lao MMI developed in this study is an effective tool for evaluating the water conditions of sites affected by human activities, particularly agricultural areas, and, thus, is appropriate for use in future studies for assessing the ecological conditions of rivers and streams in the Mekong region.

Diversity, abundance and distribution characteristics of potential polyethylene and polypropylene microplastic degradation bacterial communities in the urban river

Carbon chain microplastics, polyethylene (PE), and polypropylene (PP) are the main types of refractory organics. Compared to heterochain microplastics, PE/PP degrading bacterial community and their distribution characteristics in natural rivers are unclear. In this study, the field in situ experiment and indoor enrichment experiment with PE/PP resin as only carbon sources were conducted for a total period of 1150 days. The microbial degradation of pure PE/PP resin was determined by SEM, FTIR, CLSM, GC-MS, and GPC. The Chao 1 index and Invsimpson index of the bacterial community significantly reduced after a series of incubation, demonstrating that the bacterial community was selectively enriched. Empirical core PE/PP degrading bacteria (C-bacteria) and resuscitated PE/PP degrading bacteria (R-bacteria) were screened based on the variation of the abundance of OTUs, and co-occurrence analysis displayed that C-bacteria presented higher betweenness centrality than R-bacteria. The higher abundance and diversity of R-bacteria in biofilms suggest the presence of many rare or low abundance bacteria in natural rivers that may be potential PE/PP degrading bacteria or PE/PP degrading bacteria to be activated, while the lower abundance and diversity of C-bacteria support the slow degradation rate of PE and PP in waters. Compared to the isolated and indicatory PE/PP degrading bacterial genera, the C-bacteria OTUs or genera enriched in this study displayed higher richness and abundance. Enriched PE/PP degrading bacteria occurred in all sampled sites of the Qinhuai River with higher abundance and standard betweenness centrality in sediments (averaging 0.01354 and 0.44421, respectively) than those in overlying water (averaging 0.00536 and 0.17571, respectively), while the highest abundance of degrading bacteria presented in the eutrophic sediments. Inorganic nitrogen was determined to be significantly correlated with the distribution of PE/PP degrading bacteria in sediments via redundancy analysis. This study provides a new perspective on the natural degradation potential of carbon chain microplastics by microbial communities in rivers.

Resistance but not recovery is related to the role of specialist taxa in river communities submitted to hydric stress

One of the main effects of global change is the human interference in the global water cycle, which alters river hydrological dynamics and submits their biological communities to hydric stress. Hydric stress is a pulse disturbance with potential multiple effects on biodiversity and functions in river ecosystems. The presence of habitat specialists may support the response of biological communities to pulse disturbances, maintaining ecological functions more consistently than other communities only having generalists. We tested this general hypothesis in stream communities submitted to increasing hydric stress (normal conditions vs humidity vs desiccation). We used communities with variable proportion of specialist algal and cyanobacterial taxa and tested their resistance to hydric stress by analyzing potential changes on their number of species, biovolume, proportion of intact cells, and photosynthetic variables (basal fluorescence, photosynthetic yield). We also evaluated the recovery of ecological functions (net community primary production, community respiration, phosphorus uptake) once hydric stress conditions ended. Hydric stress caused a slight decrease in the number of species and biovolume of assemblages, but the proportion of intact cells did not significantly change because of the disturbance. Basal fluorescence and photosynthetic yield under hydric stress decreased more markedly in communities without specialist taxa, while communities with habitat specialists resisted better. Metabolism did not remarkably decrease under moderate hydric stress, but dropped by half under desiccation in all communities, having or not specialist taxa. Overall, specialist taxa did provide higher resistance to stress but did not support a distinct recovery of ecological functions. We suggest that this characteristic response is related to the high plasticity of biofilm structures.

Implications of wastewater discharges on environmental features and fish communities in an urban river

Implications of wastewater discharges on environmental features and fish communities in an urban river

Antibiotic profiles and their relationships with multitrophic aquatic communities in an urban river

Antibiotics have garnered worldwide attention due to their omnipresence and detrimental effects on aquatic organisms, yet their potential relationships with multitrophic aquatic communities in natural rivers remain largely unknown. Here, we examined 107 antibiotics in water and sediment from an urban river in Chengdu, Sichuan province (China). The bacterial, algal, macroinvertebrates, and fish communities were synchronously measured based on the environmental DNA (eDNA) metabarcoding approach, and their relationships with antibiotics were further investigated. The results showed that the total antibiotic concentrations ranged from 1.12 to 377 ng/L and from 7.95 to 145 ng/g in water and sediment, respectively. Significant seasonal variations in the concentrations and compositions of antibiotics in water were observed. eDNA metabarcoding revealed great compositional variations of bacterial, algal, macroinvertebrates, and fish communities along the river, and antibiotics had significant negative relationships with the community diversities of aquatic organisms (p < 0.05) except for fish. Meanwhile, significant negative correlations were observed between antibiotic concentrations and the relative abundances of essential metabolism pathways of bacteria, e.g., energy metabolism (p < 0.05), carbohydrate metabolism (p < 0.05), and lipid metabolism (p < 0.01). Moreover, antibiotics demonstrated greater effects on the function of bacterial community compared with environmental variables. The findings highlight the significance of eDNA metabarcoding approach in revealing the relationships between aquatic communities and antibiotics, and call for further studies on the effects of antibiotics on multitrophic aquatic communities in natural waters.

Impact of different environmental pollution processes on bacterial key-indicators in tropical rivers: Scoping review.

Freshwater ecosystems are an essential resource for human use and natural populations, but they are exposed to different sources of man-made pollution. This study analyses how different environmental pollution processes influence the structure of bacterial communities in tropical rivers. A scoping review was performed to characterize the bacterial communities in freshwater ecosystems in tropical regions that have been reported to be associated with pollution of different kinds. The statistical analyses allowed us to categorize the genera found into three large groups (pollution generalists, middle types, and pollution specialists) according to the types of pollutants with which they were associated. The results show that Escherichia has a greater association with fecal contamination, while Enterococcus is more associated with domestic wastewater and organic and synthetic chemicals. The present study proposes Streptomyces as a potential indicator of waters with microbial contamination, as well as some other genera as possible indicators of waters with heavy metal contamination.

Turbulent Streams: An Environmental History of Japan's Rivers, 1600–1930 by Roderick I. Wilson

Reviewed by: Turbulent Streams: An Environmental History of Japan's Rivers, 1600–1930 by Roderick I. Wilson Mark Metzler (bio) Turbulent Streams: An Environmental History of Japan's Rivers, 1600–1930. By Roderick I. Wilson. Brill, 2021. xiv, 294 pages. €94.00, cloth; €94.00, E-book. Roderick Wilson's Turbulent Streams is the first major study in English of the history of Japan's rivers. It focuses primarily on riparian works and the complex state-society-environment interactions they involve. Secondary focuses include river transport, river communities, fishing, and irrigation, and for the modern period, the social dynamics of engineering and policy. Geographically, it centers on the radical transformations of the Tone River system on the north side of Edo/Tokyo but also has much to say about the Yodo River system in the Kansai region, about other Japanese rivers, and about river engineering internationally. The book introduces multiple bodies of relevant scholarly literature on subjects ranging from the nature of the [End Page 162] Tokugawa state to the development of modern hydrology and civil engineering. Wilson's careful attention to the literature in Japanese and English and to questions of method and approach are present throughout. Altogether this is an important new contribution to the fast-developing field of Japanese environmental history and has major implications for the urban history of Edo/Tokyo especially. Wilson's approach to environmental history focuses on webs of environmental relations and describes human environments as places that are always in the making. To illustrate this approach, the book opens with a brief history of the former Ogura Lake, which was a wide, shallow lotus-filled lake south of Kyoto. Well represented in literature and art, Ogura Lake was a place of dense and diverse human activity, a kind of marshy "satoyama" landscape whose usage resembled that of Lake Biwa's former lagoons as described in the path-breaking analysis by Shizuya Sano. 1 Villagers dredged lake-bottom muck and used it as fertilizer, and the lake was a rich resource for fishing and for harvesting reeds and water chestnuts. As a result of the great Yodo River re-engineering project of the 1890s–1910s, it became stagnant and malarial. Ultimately it was decided to entirely fill the lake and its surrounding marshes. This was completed by 1941, creating 2,300 hectares of rice fields. Here as later, however, Wilson does not tell a simple story of decline and loss, explaining that Ogura Lake itself had long since been reshaped and recreated by human action, most notably after 1594 when Hideyoshi ordered the Uji River to be rerouted in order to construct the castle town and river port of Fushimi. The regimes the lake operated under for 250 years were varied in their goals and in their environmental and social effects. Close historical analysis of these changes will help us understand what questions to ask when it comes to planning and managing large-scale coupled human-natural systems and will widen our imagination concerning their multiple possibilities. The book is divided into two major sections, the first on the period of Tokugawa rule from 1600 to 1868 and the second on the first part of the modern period, from 1868 into the 1930s. It concludes with some discussion of the years since then. By taking in such a wide span of time, Wilson's work provides rich material for macrohistorical analysis, and in the spirit of offering a review that furthers the discussion Wilson has opened, I'll focus here on some points concerning long-run regimes in river governance and the limits they encounter. One could describe this history as a long Tokugawaera river-control cycle followed by the first phase of a long modern cycle. [End Page 163] Wilson's detailed analysis of Tokugawa-era river works is essential to his larger argument. How was it possible, in terms of supply and logistics, for the shogunal capital of Edo to grow from a fishing village into what was probably the world's largest city in 1700? This book offers some answers by elucidating the development of the Kanto region as a supply zone, with riverboat transportation being a basic part of...

Diversidade beta de Ephemeroptera, Plecoptera e Trichoptera ao longo de múltiplas escalas espaciais nas corredeiras do rio Xingu

Abstract: Aim Additive diversity partitioning has been used to explain the accumulation of diversity at different spatial scales with relative success. In lotic ecosystems, the spatial extent is extremely relevant in studies of diversity accumulation, because it encompasses environmental variation that causes changes in the observed communities. Despite of previous knowledge on the effect of extent on biological communities and diversity accumulation, little is known about the topic in aquatic insect communities in large rivers. In this context, we studied the effect of spatial extent and environmental variation on diversity components, alpha and beta, in Ephemeroptera, Plecoptera and Trichoptera (EPT) groups in Xingu River rapids. Methods The sampling was carried out in October 2015 in the dry period of the region, in nine rapids in the Xingu, Bacajá and Iriri rivers. At each collection site, five Surber samples were taken. We also recorded pH, dissolved oxygen, electrical conductivity, water temperature, and geographic coordinates. We used additive diversity partitioning to separate the diversity components α and β. For the spatial component, we generated the spatial filters using PCNM (Principal Coordinates of Neighbour Matrices) and partitioned the variance between space and environment using partial Redundancy Analysis (pRDA). Results We collected 12,249 individuals in 27 genera within 11 families in the EPT orders. The greatest accumulation of diversity was observed among rapids of the river, when the β diversity in this spatial extent was greater than the expected. The spatial structure was an indirect effect at this extent, since it is a relevant drive to environmental variables. Conclusions The results indicate that the effect of spatial extent on rapids is a contributing factor in the diversity components of aquatic insect communities in large river rapids. To the conservation and management of this environment is necessary cover as many rapids as possible, since the preservation of only a few rapids can mean a substantial loss of regional diversity.

Treatment of Native Youth Requires Incorporating Culture, Recognizing Trauma

Treatment of Native Youth Requires Incorporating Culture, Recognizing Trauma

Effect of Enlightenment on the Attitude and Participation of Adolesecents to National Matters in Nigeria

The aim of this study was to see how intervention of enlightenment about personal and national health plus wellbeing could impart the young ones concerning their attitude and participation in national matters. This study included college students from randomly selected urban and rural communities in Cross River, Edo, and Kaduna states. The current study enlisted a total of 140 participants. Structured pretested questionnaires were used to collect data. The majority of the respondents in the current study attributed health to wealth (35.4%), others defined health as total wellbeing (32.3%), clean and sanitary environment (6.3%), the fitness of mind and body (4.7%), state of wellness of mind, body, and financial ability (2.4%). 42.6% of the respondents in the current study indicated that they will improve on citizen responsibility; 19.7% said they will provide a sanitary environment whereas 12.6% indicated that good governance is necessary for the improved health of Nigeria; 5.5% noted that they staying healthy to improve the health of Nigeria; 11.8% stated that education is necessary for the nation’s improved health’ 7.9% indicated that they will improve basic amenities. The findings of this study point to an acceptance of increased citizen responsibility; the realization that the maintenance of basic amenities and the environment was critical for respondents to become aware of the growing role of the ordinary citizen in the provision and maintenance of good governance. Increased calls for Nigerians to register to vote have frequently failed to produce the desired results. According to the findings of the current study, the majority of respondents are eager to vote in the upcoming election.

Aquatic Macroinvertebrate Community Structure along a Continuum in a Spring Dominated River, Missouri, USA

The Current River is a cold-water, thermally constant Missouri Ozark stream and is one of the few remaining free-flowing rivers in the U.S. The Current River’s baseflow is largely fed by hundreds of springs, which include five first-magnitude springs. Little attention has been given to the influence of spring inflows on river temperature and spring influence on biodiversity. The objectives of this study were to demonstrate how large springs affect river macroinvertebrate communities, and to explore the relationships among macroinvertebrate diversity and habitat variables to estimate spring influences on community structure and diversity. Aquatic macroinvertebrates were collected from 42 riffle/run habitats of the Current River main-stem, tributaries, and springs during the winter season. Samples at each site were collected using a Slack-Surber sampler for macroinvertebrates with additional habitat variables collected: substrate size, embeddedness, periphyton, filamentous green algae, vegetation, depth, current velocity, temperature, dissolved oxygen, specific conductance, and pH. Beta diversity analysis was performed on consecutive pairs of site taxa richness values using the Wilson–Shmida calculation to determine the impact of main-stem confluences with either tributaries or springs, and invertebrate community relationships were explored using nonmetric multidimensional scaling (NMDS). Water temperature and taxa richness exhibited similar patterns, with higher temperatures being associated with lower taxa richness. Downstream of each large-magnitude spring, taxa richness sharply decreased, while taxa richness increased downstream of tributaries. Beta diversity usually declined downstream of the confluences with springs, but increased downstream of the tributaries. Data from large springs were closely grouped in NMDS, while tributaries and main-stem sites were more widely scattered. These data indicate spring inputs produce more homogenous conditions in the main-stem river compared to more heterogenous conditions produced by tributary inputs. Macroinvertebrate diversity along the Current River also does not follow predictions from the river continuum concept, but rather diversity peaks are downstream of springs. Our data clearly demonstrate the strong influence of large springs on macroinvertebrate communities in the Current River.

FILTRASI AIR SEDERHANA DENGAN METODE SLOW SAND FILTER UNTUK MEMPERBAIKI KUALITAS AIR SAMBUNGAN RUMAH MASYARAKAT SEKITAR SEI MERDEKA SAMBOJA KABUPATEN KUTAI KARTANEGARA

This research was conducted to help the community due to clean water problems in a simple and easy way. This research found a problem related to clean water in Sungai Merdeka Village, Samboja District, Kutai Kartanegara Regency, East Kalimantan Province. The problem experienced by the surrounding community is that the clean water that comes out of the house connection faucet cannot be used directly for cooking and drinking, but is only used for washing clothes, bathing and washing cutlery. People have consumed this water, but what happens is an uncomfortable feeling in the throat (inflammation) and when it use for bathing, it makes skin sometimes feels dry and tight. This is the reason to develop our research activities to find out how the condition of the water used by the community to fulfill their daily activities, to test the content of tap water in one of the residents' house. The efforts made to improve the quality of the Merdeka River community's tap water are by using Simple Filtration with the Slow Sand Filter principle, which is a filtering method that flows from the bottom up using several natural filter media without using chemicals. The media used include filter foam, silica sand, zeolite stone, activated carbon, palm fiber, and gauze nets. The pH value in residents' water faucets, which range from 4-6, that is not in requirements for clean water/drinking water issued by Permenkes no. 492 of 2010 which requires a pH value between 6.5 – 8.5. When compared to the pH value in the raw water source, namely the Merdeka River, it is even better, ranging from 5.6 to 6.4. The simple tool design was made, which namely Filtration with an upflow flow system (from bottom to top). The result is that after the residents' tap water is filtered through simple filtration, the air pH value becomes normal around 6.9 – 7.4. This means that the water meets the requirements set by the government according to the Minister of Health.

Winter gifts for river ecosystems: A massive supply of earthworms in early winter.

Terrestrial resource pulses can significantly affect the community dynamics of freshwater ecosystems. Previously, its effect on the river community is considered to be stronger in summer, whereas weaker in winter when terrestrial invertebrates are less abundant. The movement of the terrestrial earthworms is triggered in winter, so they may be supplied to winter rivers as terrestrial resource pulse, but little is known about it. Here, we report that the massive numbers of the terrestrial earthworms were supplied intensively to an upstream of the small river in early winter. In particular, we found large numbers of megascolecid earthworms were supplied in an upstream of the small river in Northern Japan. Furthermore, we observed that supplied earthworms were consumed by salmonid fish species (masu salmon, white spotted char and rainbow trout) and aquatic invertebrates (gammarid amphipod, planarian flatworm, and stonefly larvae). These findings suggest that the terrestrial earthworms may play a key role in ecosystem functioning in winter when severe and other resources are scarce.

Macrozoobenthic diversity and heavy metals (Pb and Hg) accumulation in Bone River Gorontalo Indonesia

The heavy metal pollution on benthic macroinvertebrate communities in Bone River has not been studied. This present study determined to investigate the diversity of the macrozoobenthic trough the length of Bone River concerning the heavy metals leads and mercury at eight sampling stations. The samples were taken in July 2021. A sample of four representative macro zoobenthic families (Hydropsychidae, Baetidae and Elmidae) was also used to analyze metal bioaccumulation. The macrozoobenthic recorded in this study comprise of ten orders and 35 families with a total of 3146 individuals. Diptera, Ephemeroptera, Coleoptera, and Trichoptera dominate the population size of benthic. The diversity indices show the low and medium categories but favour a better macrozoobenthic development. Monitoring studies show that the concentration of Pb in sediments is much higher than that of mercury. Metal accumulation in sediments showed fluctuations but did not reflect macrozoobenthic metal concentrations. The bioconcentration factor (BCF) value generally indicates that the three taxa are categorized in the low accumulative category.

Trophic interactions regulate microbial responses to environmental conditions and partially counteract nitrogen transformation potential in urban river bends

River bends are distinguished by high biodiversity and elevated rates of biogeochemical activities due to complex hydromorphological processes that form diverse geomorphic units, making it challenging to elucidate the impact of trophic interactions on community assembly and biogeochemical processes. Here, we clarify the effect of trophic interactions in determining the assembly of multi-trophic microbial communities and the impact on nitrogen transformation potential by distinguishing the direct and cascading effects of environmental conditions based on 32 samples collected from a typical urban river bends. It was found that both bacterial and micro-eukaryotic communities were determined by homogeneous selection (indicated by β-nearest taxon index, accounted for 85% and 48.3%, respectively), whereas the dominant environmental factors were different, being sediment particle size (P < 0.05) and nitrogen (P < 0.05), respectively. Both the microbial co-occurrence network and the significant association (P < 0.05) between β-nearest taxon index and trophic transfer efficiency changes showed that the trophic interactions strongly shaped microbial communities in the urban river bends. The path modeling suggested that environmental conditions resulted in an increase in abundance of multi-trophic microbial communities via direct effects (mean standardized effects = 0.21), but reductions in abundance of bacteria via cascading effects, i.e., trophic interaction (mean standardized effects = −0.1). When considering direct and cascading effects together, environmental conditions in urban river bends were found to enhance the abundance of microbial communities, with decreasing magnitude at the higher trophic level. Analogously, the path modeling also indicated the nitrogen transformation potential enhanced by environmental conditions via direct effects, but partly counteracted by trophic interactions via cascading effects. The obtained results could provide a theoretical basis for the regulation and restoration of urban rivers.

Indigenous Service Provider Perspectives of an Online Education Module to Support Safe Clinical Encounters about Family Violence in Canada.

Given colonial genocide, Indigenous peoples are rightfully reticent to disclose their experiences of family violence to practitioners working within mainstream health care and social services. Health care and social service providers (HSSPs) have varied formal education on providing trauma-and-violence informed care to Indigenous and non-Indigenous families affected by family violence, including intimate partner violence and child maltreatment. The purpose of this study is to understand and describe the perspectives of Six Nations of the Grand River community members on the relevance of an education module to support HSSPs to provide physically and emotionally safe care to Indigenous families affected by family violence. Two-Eyed Seeing and Two Row Wampum approaches guided our qualitative study. Twenty-one (66.7% women) Indigenous HSSPs completed a semi-structured interview; 15 identified as a regulated HSSP, nine as a Knowledge Keeper/Cultural Holder, and three as a HSSP trainees. Conventional content analysis guided the development of codes and categories. The Violence, Evidence, Guidance, Action (VEGA)-Creating Safety education module was described as having elements consistent with Indigenous experiences and values, and supportive of Indigenous peoples seeking care from HSSPs for family violence related concerns. Participants described several suggestions to better adapt and align the module content with the diversity of values and beliefs of different Indigenous Nations. Collectively, the Creating Safety module may be used as an educational adjunct to Indigenous-focused, cultural safety training that can support HSSPs to provide physically, emotionally, and psychologically safe care to Indigenous peoples who have experienced family violence. Future work needs to consider the perspectives of other Indigenous communities and Nations.

Large-scale spatial patterns of riverine communities: niche versus geographical distance

Freshwater ecosystems are among the most threatened ecosystems on Earth. Effective conservation strategies are essential to reverse this trend and should be based on sound knowledge of biodiversity patterns and the main drivers structuring them. In this study, we investigated the role of environmental and dispersal-connectivity controls on freshwater diatom and fish communities’ variability. We used 441 biological samples obtained from Spanish biomonitoring datasets, which cover a highly variable environmental gradient across the national river network. We compared the taxonomic and trait-based spatial dependency of the two biotic groups using distance-decay relationships and variation partitioning with spatially constrained randomisations. Our findings showed that most of the diatoms and fish biological variation was attributed to pure spatial and spatially structured environmental variation. Compared to diatoms, fish community composition presented a stronger spatial dependency, likely because of their weaker dispersal ability. In addition, broad-scale environmental characteristics showed a higher predictive capacity for fish assemblages’ variation. Trait-based similarities presented lower spatial dependency than taxonomic datasets, indicating that they are less susceptible to dispersal-connectivity effects. These findings contribute to understand the mechanisms underlying river community assembly at large spatial scales (i.e., at and beyond the river network) and point out the importance of dispersal-connectivity processes, which are usually neglected in traditional niche-based biomonitoring programmes but can influence their outcomes (e.g., masking the detection of anthropogenic impacts). Therefore, the integration of the dispersal-connectivity component, as well as information on organisms’ dispersal abilities, are crucial when establishing effective conservation objectives and designing biomonitoring strategies.

Assessing the effects of irrigation and hydropower dams on river communities using taxonomic and multiple trait-based approaches

Rivers and streams have suffered multiple transformations to attend the increasing water demands worldwide. Among these, dams and reservoirs cause some of the most severe ecological impacts on rivers, altering the river flow and thermal regimens, nutrient and sediment fluxes, and network connectivity. However, in the context of the different dam purposes and operational schemes, knowledge of the ecological impacts on the riverine biota is still limited. In this study, our main goal was to assess dam-related effects (e.g. hydrological and thermal alteration, water quality changes) on river biological communities and identify key ecological responses associated to flow regulation. To achieve this, diatom, macroinvertebrate, and fish communities were surveyed in control (n = 8) and impacted (n = 11) streams (i.e. downstream of irrigation or hydropower dams) along three consecutive years. The study design aimed at minimising the environmental variability among control and impacts using previously established hydrological classifications. This allowed focusing primarily on the effects of dam operation schemes. In addition to traditional biotic indices based on the composition and structure of these communities, we assessed community-level responses using trait-based analyses with multivariate and fourth-corner analyses. The ecological changes varied with dam purpose and, in general, favoured disturbance-tolerant traits. Common biotic indices did not consistently respond to dam uses; trait-based analyses, in contrast, provided a more detailed picture of the dam-related effects on the studied river communities, with macroinvertebrate traits showing the strongest correlations to dam-related hydrological and physico-chemical variables, followed by diatoms and fish. Changes in the biological communities downstream of irrigation dams were mostly related to the inversion of the seasonal flow regimes (e.g. increases in the summer flows and magnitude of low flow extremes; decreases in the winter flows and in the frequency and magnitude of extreme high flow events) and the reduction of nutrient concentration. These changes favoured planktonic diatoms, macroinvertebrates with short life cycles and small body sizes, and fish feeding on the water column. Hydropower dams elevated significantly the rate of flow change and water temperature, favouring low profile adnate diatoms, multivoltine and passively dispersed macroinvertebrates, and scrapers. The key relationships identified in our study are useful to underpin river biodiversity conservation strategies and to set future research directions aiming at reducing the negative effects of dam operation schemes.

Antibiotic properties of Satureja montana L. hydrolate in bacteria and fungus of clinical interest and its impact in non-target environmental microorganisms

The aim of this study was to analyse the microbicidal and microbiostatic activity of S. montana hydrolate L., the water-soluble fraction of the hydro-distillation process used to obtain the essential oil, on 14 Gram-positive and Gram-negative bacteria and a fungus of clinical interest. To consider whether this hydrolate is a more environmentally friendly alternative to traditional antibiotics, its effect on non-target microorganisms in the aquatic and terrestrial environment was analysed using natural soil and river microorganism communities, characterized through 16S rRNA gene sequencing. Results showed that S. montana hydrolate was especially effective (25% v/v concentration) against Pasteurella aerogenes, Streptococcus agalactiae and Acinetobacter baumannii (priority 1, WHO). It was also a microbicide for a further 7 bacterial strains and the fungus Candida albicans (50% v/v concentration). The river and soil communities exposed to the hydrolate showed a decrease in their growth, as well as a decrease in their ability to metabolize polymers and carbohydrates (soil microorganisms) and polymers, carboxylic and ketone acids (river microorganisms). Hydrolates could be an alternative to conventional antibiotics, but their impact on the environment must be taken into account.