Physical habitat modeling for river macroinvertebrate communities

Habitat models rarely consider macroinvertebrate communities as ecological targets in rivers. Available approaches mainly focus on single macroinvertebrate species, not addressing the ecological needs and functionality of the whole community. This research aimed at providing an approach to model the habitat of the macroinvertebrate communities. The study was carried out in three rivers, located in Italy and characterized by a braiding morphology, gravel riverbeds, and low flows during the summer period. The approach is based on the recently developed Flow-T index, together with a Random Forest (RF) regression, which is employed to apply the Flow-T index at the mesohabitat scale. Using different datasets gathered from field data collection and 2D hydrodynamic simulations, the model was calibrated in the Trebbia River (2019 field campaign) and validated in the Trebbia, Taro, and Enza rivers (2020 field campaign). The RF model selected 12 mesohabitat descriptors as important for the macroinvertebrate community. These descriptors belong to different frequency classes of water depth, flow velocity, substrate grain size, and connectivity to the main river channel. The cross-validation R2 coefficient (R2cv) of the training dataset was 0.71, whereas the R2 coefficient (R2test) for the validation dataset was 0.63. The agreement between the simulated results and the experimental data shows sufficient accuracy and reliability. The outcomes of the study reveal that the model can identify the ecological response of the macroinvertebrate community to possible flow regime alterations and river morphological modifications. Lastly, the proposed approach allowed to extend the MesoHABSIM methodology, widely used for the fish habitat assessment, to a different ecological target community. Further applications of the approach can be related to ecological flows design in both perennial and non-perennial rivers, including river reaches in which fish fauna is absent.

Color polymorphism and mating trends in a population of the alpine leaf beetle Oreina gloriosa

The bright colors of Alpine leaf beetles (Coleoptera, Chrysomelidae) are thought to act as aposematic signals against predation. Within the European Alps, at least six species display a basal color of either blue or green, likely configuring a classic case of müllerian mimicry. In this context, intra-population color polymorphism is paradoxical as the existence of numerous color morphs might hamper the establishment of a search image in visual predators. Assortative mating may be one of the main factors contributing to the maintenance of polymorphic populations. Due to the marked iridescence of these leaf beetles, the perceived color may change as the viewing or illumination angle changes. The present study, conducted over three years, involved intensive sampling of a population of Oreina gloriosa from the Italian Alps and applied colorimetry and a decision tree method to identify the color morphs in an objective manner. The tertiary sex ratio of the population was biased in favor of males, suggesting that viviparous females hide to give birth. Seven color morphs were identified, and their frequencies varied significantly over the course of the study. Three different analyses of mating (JMating, QInfomating, and Montecarlo simulations) recognized a general trend for random mating which coexists with some instances of positive and negative assortative mating. This could help explain the pre-eminence of one morph (which would be favored because of positive selection due to positive assortative mating) in parallel with the persistence of six other morphs (maintained due to negative assortative mating).

Spatio-temporal modelling suggests that some dung beetle species (Coleoptera: Geotrupidae) may respond to global warming by boosting dung removal

In the current framework of changes to the global climate, information on the thermal tolerance of dung beetles is crucial to understand how they might cope with increases in land temperature in terms of survival and ecosystem service provision. In this spatio-temporal modelling study, we investigated the thermal tolerance and effect of temperature changes on dung removal by three dung beetle species (Coleoptera: Geotrupidae) living within the 600-1400 m altitudinal belt in the Italian Alps. We chose large tunneler beetles because of their pivotal role in dung removal and nutrient recycling, important ecosystem services for maintaining the viability and profitability of the Alpine pastoral system. Our study used experimental data on dung removal at different temperatures to predict changes to this ecosystem service in the future considering different climatic scenarios and changes in land use for the specific study area. The results show that the temperature increases incurred between 1981 and 2005 may have boosted rates of spring dung removal across the entire study area (expressed as average dung removal per pair per month), partially compensating for the reduction in grassland extent within pasture-based livestock farming systems. Despite the limitations related to modelling future climate change scenarios and uncertainties deriving from several interacting factors (e.g., the sensitivity of large-bodied species to land-use changes), our results suggest that the predicted increases in temperature over the next 80 years would continue to boost dung removal, revealing a resilience of this service. The increase in dung removal rates, for all three species, is mainly related to the most extreme scenario of carbon emissions and for the months spanning from May to October of the interval 2041-2100. Focusing on large tunnelers and adopting a dynamic approach that considers changes in dung removal over space and time can assist ecosystem service conservation planning.

The foraging ecology of yellow-billed and red- billed choughs changed between two climatically different years

Climate change is affecting the alpine ecosystem at an unprecedented rate, with marked changes in spring phenology and the elevation distribution of birds. Changes in the European Alps are happening rapidly, and it is possible behaviours stand to change from one year to the next. The year 2022 was characterised by climatic extremes: Italy experienced its hottest year ever, and it was the driest since 1800. Here, we assessed whether the foraging ecology of two coexisting upland bird species, the yellow-billed and the red-billed chough, changed from 2021 to 2022. We assessed foraging stay times, flock size, propensity to mixed flocking, foraging home ranges and altitudinal distribution. Stay times of both species when foraging in monospecific flocks significantly shortened in 2022, especially in the case of the red-billed chough. The two corvids are known to influence each other when foraging together. In 2021, as expected, the stay times of the red-billed chough decreased when in the presence of the congener, but this did not occur in 2022. Instead, the yellow-billed chough increased its altitudinal foraging distribution in 2022. The results are in line with the hypothesis that large climate variations may disrupt the foraging ecology of mountain birds. However, as it is not possible to draw solid conclusions from just two years of observations, further field research will have to be planned in the future.

Climate change impact on the ecological status of rivers: The case of Albaida Valley (SE Spain)

Understanding the effects of environmental stressors (e.g., potential changes in climate and land use) on ecological status is essential for freshwater management. The ecological response of rivers to stressors can be evaluated by several physico-chemical, biological, and hydromorphological elements as well as computer tools. In this study, an ecohydrological model based on SWAT (Soil and Water Assessment Tool) is used to investigate climate change impact on the ecological status of Albaida Valley Rivers. The predictions of five General Circulation Models (GCMs) each with four Representative Concentration Pathways (RCPs) are employed as input to the model for simulating several chemical and biological quality indicators (nitrate, ammonium, total phosphorus, and the IBMWP (Iberian Biological Monitoring Working Party) index) in three future periods (Near Future: 2025-2049, Mid Future: 2050-2074, and Far Future: 2075-2099). Based on chemical and biological status predicted with the model, the ecological status is determined at 14 representative sites. As a result of increased temperatures and decreased precipitations from most of GCMs projections, the model predicts decreased river discharge, increased concentrations of nutrients, and decreased values of IBMWP for future compared to the baseline period (2005-2017). While most representative sites have poor ecological status (10 sites with poor ecological status and four sites with bad ecological status) in the baseline, our model projects bad ecological status for most representative sites (four sites with poor ecological status and 10 sites with bad ecological status) under most emission scenarios in the future. It should be noted that the bad ecological status is projected for all 14 sites under the most extreme scenario (i.e., RCP8.5) in the Far Future. Despite the different emission scenarios, and all possible changes in water temperature and annual precipitation, our findings emphasize the urgent need for scientifically informed decisions to manage and preserve freshwaters.

Behavioural Repeatability and Behavioural Syndrome in the Dung Beetle Copris umbilicatus (Coleoptera, Scarabaeidae)

Although personality studies have primarily focused on vertebrates, the evidence showing invertebrates to be capable of displaying personalities has been steadily growing in recent years. In this study, we investigated the behavioural repeatability (repetition of a behaviour over time) and behavioural syndromes (a set of correlated behaviours) in Copris umbilicatus, which is a dung beetle species showing complex sub-social behaviour. We analysed three behaviours (activity, thanatosis and distress call emission) by measuring seven distinct behavioural traits (i.e., three activity-, one thanatosis- and three distress call-related traits). We found moderate to high levels of individual repeatability in all behavioural traits considered. The duration of thanatosis was inversely correlated with two activity traits, hinting a behavioural syndrome for thanatosis and activity, with bolder individuals exhibiting shorter thanatosis and higher locomotor activity in contrast with fearful individuals, which display longer thanatosis and poor locomotor activity. No relationships were found between the behavioural traits and body size or sex. Results of the principal component analysis (PCA) suggested personality differences among individuals. Dung beetles provide an impressive variety of ecosystem services. Since the provision of these services may depend on the personalities represented in local populations and communities, studies on the ecology of personality in dung beetles should be encouraged in future research.

Among demons and killers: current and future potential distribution of two hyper successful invasive gammarids

Biological invasions represent one of the main contemporary pressures facing freshwater ecosystems, and a better understanding of invasive species potential distributions is essential to prepare for future stressors. Crustacean invaders contribute significantly to global invasions with the Ponto-Caspian region being one of the primary donor areas for the Palearctic. The amphipods Dikerogammarus villosus and Dikerogammarus haemobaphes, popularly known as “killer” and “demon” shrimps, are emblematic of successful Ponto-Caspian invaders of European freshwaters. However, the geographical areas in which the abiotic environment is potentially suitable for them have not been investigated. To address this gap, current and future potential distributions were studied for the European Western Palearctic considering two scenarios and time periods (2050 and 2070) as well as the association between anthropogenic activities and individual species habitat suitability. Results show large areas of central-western Europe are currently suitable for both species and indicate some potential for range expansion within colder European areas. In particular, D. haemobaphes has the potential to expand its range further west and within southern parts of Europe. Scenarios of future climate change don’t provide evidence for further range expansion compared to the current conditions and suggest a reduction of range overlap within the most suitable areas. Results reveal lowland areas are at greatest risk of colonisation as well as a significant association with anthropogenic activities for both amphipods. The outcomes of the research could be used by resource managers for preparing and managing future changes of both species distributions and facilitate decision-making for monitoring and control.

biomonitoR: an R package for managing ecological data and calculating biomonitoring indices

The monitoring of biological indicators is required to assess the impacts of environmental policies, compare ecosystems and guide management and conservation actions. However, the growing availability of ecological data has not been accompanied by concomitant processing tools able to facilitate data handling and analysis. Multiple common challenges limit the usefulness of biomonitoring information across ecosystems and biological groups. Biomonitoring data analysis is currently constrained by time-consuming steps for data preparation and a data processing environment with limited integration in terms of software, biological groups, and protocols. We introduce biomonitoR, a package for the R programming language that addresses technical challenges for the management of ecological data and metrics calculation. biomonitoR implements most of the biological indices currently used or proposed in different fields of ecology and water resource management. Its combination of customizable functions aims to support a transferable and comprehensive biomonitoring workflow in a user-friendly environment. biomonitoR represents a versatile toolbox with five main assets: (i) it checks taxonomic information against reference datasets allowing for customization of trait and sensitivity scores; (ii) it supports heterogeneous taxonomic resolution allowing computations at multiple taxonomic levels; (iii) it calculates multiple biological indices, including metrics for both broad and stressor-specific ecological assessments; (iv) it enables user-friendly data visualization, helping both decision-making processes and data interpretation; and (v) it allows working with an interactive web application straight from R. Overall, biomonitoR can benefit the wide biomonitoring community, including environmental private consultants, ecologists and natural resource managers.

Using invertebrate functional traits to improve flow variability assessment within European rivers

Rivers are among the most threatened ecosystems worldwide and are experiencing rapid biodiversity loss. Flow alteration due to climate change, water abstraction and augmentation is a severe stressor on many aquatic communities. Macroinvertebrates are widely used for biomonitoring river ecosystems although current taxonomic approaches used to characterise ecological responses to flow have limitations in terms of generalisation across biogeographical regions. A new macroinvertebrate trait-based index, Flow-T, derived from ecological functional information (flow velocity preferences) currently available for almost 500 invertebrate taxa at the European scale is presented. The index was tested using data from rivers spanning different biogeographic and hydro-climatic regions from the UK, Cyprus and Italy. The performance of Flow-T at different spatial scales and its relationship with an established UK flow assessment tool, the Lotic-invertebrate Index for Flow Evaluation (LIFE), was assessed to determine the transferability of the approach internationally. Flow-T was strongly correlated with the LIFE index using both presence-absence and abundance weighted data from all study areas (r varying from 0.46 to 0.96). When applied at the river reach scale, Flow-T was effective in identifying communities associated with distinct mesohabitats characterised by their hydraulic characteristics (e.g., pools, riffles, glides). Flow-T can be derived using both presence/absence and abundance data and can be easily adapted to varying taxonomic resolutions. The trait-based approach facilitates research using the entire European invertebrate fauna and can potentially be applied in regions where information on taxa-specific flow velocity preferences is not currently available. The inter-regional and continental scale transferability of Flow-T may help water resource managers gauge the effects of changes in flow regime on instream communities at varying spatial scales.

Continuous phenotypic modulation explains male horn allometry in three dung beetle species

Many dung beetle species show male horn polyphenism, the ability of males to develop into distinct phenotypes without intermediate forms as a response to the larval growth environment. While males with long (majors) and rudimentary (minor) horn have been widely reported in literature, little is known about the existence of individuals with intermediate horn length. Here we investigate the occurrence of intermediates in natural populations of three dung beetle species (Onthophagus furcatus, Copris lunaris and C. hispanus). We analysed the body size-horn length relationship using linear, exponential, and sigmoidal models with different error structures. We inferred the number of individuals in the minor, intermediate, and major groups by combining changepoint analysis and simulation from fitted allometric models. The sigmoidal equation was a better descriptor of the body size-horn length relationship than linear or exponential equations in all the three studied species. Our results indicated that the number of intermediates equals or exceeds the number of minor and major males. This work provides evidence that, at least in the studied species, males with intermediate horn length exist in natural populations. For similar cases we therefore suggest that continuous phenotypic modulation rather than discrete polyphenism can explain variation in male horn allometry.

Interactions Between Individuals and Sex Rather Than Morphological Traits Drive Intraspecific Dung Removal in Two Dung Beetle Species

Dung beetle functional ecology has traditionally focused on studying the relation between traits and ecosystem functions in multispecies assemblages, often ignoring the contribution of behavioral interactions and trait variability within species. Here we focus on the factors that affect dung removal at an intraspecific level in two horned dung beetle species with dimorphic males (Onthophagus taurus and Onthophagus verticicornis). By setting treatments for each species with single individuals (one female, F; one major male, M; one minor male, m) or with pairs of individuals (MF, mF, MM, mm, FF), we examined the effect on dung removal of morphological traits (head, pronotum, leg, horn), sex, and interactions between individuals. Our results showed that dung removal at an intraspecific level depended more on sex and behavioral interactions than on the underlying morphological traits, whose effects on dung removal were negligible. Single females generally removed more dung than single males, which suggests that females are more effective than males. In both species, pairs with at least one female (MF, mF, FF) showed high dung removal efficiency, but did not perform differently from the sum of single treatments (M + F, m + f, F + F). This suggests an additive effect: males and females (or two females) join their efforts when they are together. The pairs with only males (MM and mm) removed less dung than the sum of the single individuals (M + M and m + m), which indicates a mutual inhibition of males. In both species, male morphs performed similarly as they removed the same amount of dung. Despite our results are limited to two Onthophagus species, we suggest that the intraspecific functional ecology of dung beetles might be more influenced by behavioral interactions and sex rather than by morphological traits.

Multiple co-occurrent alien invaders constrain aquatic biodiversity in rivers

A greater understanding and effective management of biological invasions is a priority for biodiversity conservation globally. Many freshwater ecosystems are experiencing the colonization and spread of multiple co-occurrent alien species. Here the implications of both the relative abundance and richness of alien invaders on aquatic macroinvertebrate taxonomic and functional richness, ecosystem quality, and functional redundancy are assessed using long-term data from rivers in England. Based on the most common aquatic invaders, results indicated that their richness, rather than abundance, was the most important factor negatively affecting aquatic macroinvertebrate biodiversity. However, the response of functional redundancy was negatively affected by invader abundance at the river basin scale. The response of communities varied as the number of invading taxa increased, with the most marked reductions following the colonization of the first few invaders. Results indicate that different facets of multiple biological invasions influence distinct aspects of aquatic biodiversity. Preventing the establishment of new invaders and limiting invader taxa richness within a community should therefore be a conservation priority. These findings will assist river scientists in understanding mechanisms driving changes in biodiversity and facilitate the testing of ecological theories while also ensuring environmental managers and regulators can prioritize conservation / management opportunities.

Exploring the potential of metabarcoding to disentangle macroinvertebrate community dynamics in intermittent streams

Taxonomic sufficiency represents the level of taxonomic detail needed to detect ecological patterns to a level that match the requirement of a study. Most bioassessments apply the taxonomic sufficiency concept and assign specimens to the family or genus level given time constraints and the difficulty to correctly identify species. This holds particularly true for stream invertebrates because small and morphologically similar larvae are hard to distinguish. Low taxonomic resolution may hinder detecting true community dynamics, which thus leads to incorrect inferences about community assembly processes. DNA metabarcoding is a new, affordable and cost-effective tool for the identification of multiple species from bulk samples of organisms. As it provides high taxonomic resolution, it can be used to compare results obtained from different identification levels. Measuring the effect of taxonomic resolution on the detection of community dynamics is especially interesting in extreme ecosystems like intermittent streams to test if species at intermittent sites are subsets of those from perennial sources or if independently recruiting taxa exist. Here we aimed to compare the performance of morphological identification and metabarcoding to detect macroinvertebrate community dynamics in the Trebbia River (Italy). Macroinvertebrates were collected from four perennial and two intermittent sites two months after flow resumption and before the next dry phase. The identification level ranged from family to haplotype. Metabarcoding and morphological identifications found similar alpha diversity patterns when looking at family and mixed taxonomic levels. Increasing taxonomic resolution with metabarcoding revealed a strong partitioning of beta diversity in nestedness and turnover components. At flow resumption, beta diversity at intermittent sites was dominated by nestedness when family-level information was employed, while turnover was evidenced as the most important component when using Operational Taxonomic Units (OTUs) or haplotypes. The increased taxonomic resolution with metabarcoding allowed us to detect species adapted to deal with intermittency, like the chironomid Cricotopus bicinctus and the ephemeropteran Cloeon dipterum. Our study thus shows that family and mixed taxonomic level are not sufficient to detect all aspects of macroinvertebrate community dynamics. High taxonomic resolution is especially important for intermittent streams where accurate information about species-specific habitat preference is needed to interpret diversity patterns induced by drying and the nestedness/turnover components of beta diversity are of interest to understand community assembly processes.

Tracking down carbon inputs underground from an arid zone Australian calcrete

Freshwater ecosystems play a key role in shaping the global carbon cycle and maintaining the ecological balance that sustains biodiversity worldwide. Surficial water bodies are often interconnected with groundwater, forming a physical continuum, and their interaction has been reported as a crucial driver for organic matter (OM) inputs in groundwater systems. However, despite the growing concerns related to increasing anthropogenic pressure and effects of global change to groundwater environments, our understanding of the dynamics regulating subterranean carbon flows is still sparse. We traced carbon composition and transformations in an arid zone calcrete aquifer using a novel multidisciplinary approach that combined isotopic analyses of dissolved organic carbon (DOC) and inorganic carbon (DIC) (δ13CDOC, δ13CDIC, 14CDOC and 14CDIC) with fluorescence spectroscopy (Chromophoric Dissolved OM (CDOM) characterisation) and metabarcoding analyses (taxonomic and functional genomics on bacterial 16S rRNA). To compare dynamics linked to potential aquifer recharge processes, water samples were collected from two boreholes under contrasting rainfall: low rainfall ((LR), dry season) and high rainfall ((HR), wet season). Our isotopic results indicate limited changes and dominance of modern terrestrial carbon in the upper part (northeast) of the bore field, but correlation between HR and increased old and 13C-enriched DOC in the lower area (southwest). CDOM results show a shift from terrestrially to microbially derived compounds after rainfall in the same lower field bore, which was also sampled for microbial genetics. Functional genomic results showed increased genes coding for degradative pathways-dominated by those related to aromatic compound metabolisms-during HR. Our results indicate that rainfall leads to different responses in different parts of the bore field, with an increase in old carbon sources and microbial processing in the lower part of the field. We hypothesise that this may be due to increasing salinity, either due to mobilisation of Cl- from the soil, or infiltration from the downstream salt lake during HR. This study is the first to use a multi-technique assessment using stable and radioactive isotopes together with functional genomics to probe the principal organic biogeochemical pathways regulating an arid zone calcrete system. Further investigations involving extensive sampling from diverse groundwater ecosystems will allow better understanding of the microbiological pathways sustaining the ecological functioning of subterranean biota.

Analysis of 13,312 benthic invertebrate samples from German streams reveals minor deviations in ecological status class between abundance and presence/absence data

Benthic invertebrates are the most commonly used organisms used to assess ecological status as required by the EU Water Framework Directive (WFD). For WFD-compliant assessments, benthic invertebrate communities are sampled, identified and counted. Taxa × abundance matrices are used to calculate indices and the resulting scores are compared to reference values to determine the ecological status class. DNA-based tools, such as DNA metabarcoding, provide a new and precise method for species identification but cannot deliver robust abundance data. To evaluate the applicability of DNA-based tools to ecological status assessment, we evaluated whether the results derived from presence/absence data are comparable to those derived from abundance data. We analysed benthic invertebrate community data obtained from 13,312 WFD assessments of German streams. Broken down to 30 official stream types, we compared assessment results based on abundance and presence/absence data for the assessment modules “organic pollution” (i.e., the saprobic index) and “general degradation” (a multimetric index) as well as their underlying metrics.

In 76.6% of cases, the ecological status class did not change after transforming abundance data to presence/absence data. In 12% of cases, the status class was reduced by one (e.g., from good to moderate), and in 11.2% of cases, the class increased by one. In only 0.2% of cases, the status shifted by two classes. Systematic stream type-specific deviations were found and differences between abundance and presence/absence data were most prominent for stream types where abundance information contributed directly to one or several metrics of the general degradation module. For a single stream type, these deviations led to a systematic shift in status from ‘good’ to ‘moderate’ (n = 201; with only n = 3 increasing). The systematic decrease in scores was observed, even when considering simulated confidence intervals for abundance data. Our analysis suggests that presence/absence data can yield similar assessment results to those for abundance-based data, despite type-specific deviations. For most metrics, it should be possible to intercalibrate the two data types without substantial efforts. Thus, benthic invertebrate taxon lists generated by standardised DNA-based methods should be further considered as a complementary approach.

New light in the dark - a proposed multidisciplinary framework for studying functional ecology of groundwater fauna

Groundwaters provide the vast majority of unfrozen freshwater resources on the planet, but our knowledge of subsurface ecosystems is surprisingly limited. Stygofauna, or stygobionts -subterranean obligate aquatic animals - provide ecosystem services such as grazing biofilms and maintaining water quality, but we know little about how their ecosystems function. The cryptic nature of groundwaters, together with the high degree of local endemism and stygofaunal site-specific adaptations, represent major obstacles for the field. To overcome these challenges, and integrate biodiversity and ecosystem function, requires a holistic design drawing on classical ecology, taxonomy, molecular ecology and geochemistry. This study presents an approach based on the integration of existing concepts in groundwater ecology with three more novel scientific techniques: compound specific stable isotope analysis (CSIA) of amino acids, radiocarbon analysis (¹⁴C) and DNA analyses of environmental samples, stygofauna and gut contents. The combination of these techniques allows elucidation of aspects of ecosystem function that are often obscured in small invertebrates and cryptic systems. Carbon (δ¹³C) and nitrogen (δ¹⁵N) CSIA provides a linkage between biogeochemical patterns and ecological dynamics. It allows the identification of stygofaunal food web structures and energy flows based on the metabolic pathway of specific amino groups. Concurrently, ¹⁴C provides complementary data on the carbon recycling and incorporation within the stygobiotic trophic webs. Changes in groundwater environmental conditions (e.g. aquifer recharge), and subsequent community adaptations, can be pinpointed via the measurementof the radiocarbon fingerprint of water, sediment and specimens. DNA analyses are a rapidly expanding approach in ecology. eDNA is mainly employed as a biomonitoring tool, while metabarcoding of individuals and/or gut contents provides insight into diet regimes. In all cases, the application of the approaches in combination provides more powerful data than any one alone. By combining quantitative (CSIA and ¹⁴C) and qualitative (eDNA and DNA metabarcoding) approaches via Bayesian Mixing Models (BMM), linkages can be made between community composition, energy and nutrient sources in the system, and trophic function. This suggested multidisciplinary design will contribute to a more thorough comprehension of the biogeochemical and ecological patterns within these undervalued but essential ecosystems.

Space and time variations of watershed N and P budgets and their relationships with reactive N and P loadings in a heavily impacted river basin (Po river, Northern Italy)

The aim of the present study is to analyze relationships between land uses and anthropogenic pressures, and nutrient loadings in the Po river basin, the largest hydrographic system in Italy, together with the changes they have undergone in the last half century. Four main points are addressed: 1) spatial distribution and time evolution of land uses and associated N and P budgets; 2) long-term trajectories of the reactive N and P loadings exported from the Po river; 3) relationships between budgets and loadings; 4) brief review of relationships between N and P loadings and eutrophication in the Northern Adriatic Sea. Net Anthropogenic N (NANI) and P (NAPI) inputs, and N and P surpluses in the cropland between 1960 and 2010 were calculated. The annual loadings of dissolved inorganic nitrogen (DIN) and soluble reactive phosphorus (SRP) exported by the river were calculated for the whole 1968-2016 period. N and P loadings increased from the 1960s to the 1980s, as NAPI and NANI and N and P surpluses increased. Thereafter SRP declined, while DIN remained steadily high, resulting in a notable increase of the N:P molar ratio from 47 to 100. In the same period, the Po river watershed underwent a trajectory from net autotrophy to net heterotrophy, which reflected its specialization toward livestock farming. This study also demonstrates that in a relatively short time, i.e. almost one decade, N and P sources were relocated within the watershed, due to discordant environmental policies and mismanagement on the local scale, with frequent episodes of heavy pollution. This poses key questions about the spatial scale on which problems have to be dealt with in order to harmonize policies, set sustainable management goals, restore river basins and, ultimately, protect the adjacent coastal seas from eutrophication.

Aquatic Plant Diversity in Italy: Distribution, Drivers and Strategic Conservation Actions

Italy is recognized as one of the prominent hot spot areas for plant diversity at regional and global scale, hosting a rich range of ecosystems and habitat types. This is especially true considering aquatic habitats, which represent a major portion of the total water surfaces in the Mediterranean region. Nevertheless, only a scant attention was paid to clarify the species richness of aquatic plant and its contribution to the total diversity at the country scale, despite such plants are seriously threatened at multiple scales. This paper provided the first comprehensive inventory of aquatic plants at the whole country scale, collecting data on species' distribution, trends, and explanatory determinants of species richness. We confirmed the key contribution of Italy to the regional and global aquatic plant diversity with a total of 279 species recorded since 2005, equal to the 88.5%, 55.9% and ∼10% of the richness estimated at European/Mediterranean, Palearctic and global scale, respectively. Ten species are considered extinct in the wild [among which Aldrovanda vesiculosa L., Caldesia parnassifolia (Bassi ex L.) Parl., Helosciadium repens (Jacq.) W.J.D. Koch, and Pilularia globulifera L.], four were doubt [among which Luronium natans (L.) Raf., Utricularia intermedia Hayne, and U. ochroleuca R.W. Hartman.], and eight were erroneously reported in the past, among which Isoëtes lacustris L., Myosotis rehsteineri Wartm., and Ranunculus aquatilis L. Only 18 species - mainly helophytes (14) - were present in all the 20 Italian regions, whereas hydrophytes showed most scanty regional frequencies. Temperature, latitude, area and water resources availability are the main drivers of aquatic plant spatial arrangement and diversity. Furthermore, the number of inhabitants per km2 well described the number of "lost species" since 2000. The findings of the present survey call for an urgent elaboration of large-scale strategies to ensure the survival of aquatic plants, stressing on multiple functions played by aquatic plants in supporting national economy and human well-being. In this context, Italy can play a fundamental role guaranteeing temporary refuge for projected or expected species migrations along latitude and longitude gradients. Besides, in hyper-exploited landscapes man-made water bodies can further enhance the achievement of minimum conservation targets.

Fragmentation and groundwater supply as major drivers of algal and plant diversity and relative cover dynamics along a highly modified lowland river

Algae and aquatic vascular plants were investigated along a highly modified medium-sized lowland river (Oglio River, northern Italy). We focused on the role of fragmentation and groundwater supply in driving macrophyte assemblages, paying particular attention to soft-bodied benthic algae. Four different a priori stretch types (dammed, groundwater-dependent, potamal and rhithral) were identified along the river longitudinal gradient as proxies of river hydrology and relative human-induced flow alterations. Over three years (2009-2011), taxa diversity, cover data, spatial and temporal dynamics and indicator and detector species were compared with physical, chemical and hydrological variables at 30 different river sites. Data was explored by indicator species analysis, nonmetric multidimensional scaling, and PROTEST. A total of 88 taxa, of which 36 were algae (equal to 40.9% of the total diversity), 3 bryophytes (3.4%) and 49 vascular plants (55.7%), were recorded. Taxa diversity peaked at the groundwater-dependent sites for both algae and vascular plants (with a mean of 12.8±2.7 and 12.7±4.8 taxa per site, respectively). Algae cover values were one order of magnitude higher than those of vascular plants (with an overall mean of 37.0±24.2% per site). The vascular plants counterbalanced the algae coverage values exclusively at the dammed sites (27.6±23.2% vs 28.2±13.9%, respectively). A clear zonation of communities emerged from the multivariate analysis, which revealed taxa rearrangements that largely overlapped the river stretch types. Inter-annual comparisons confirmed the strong stability of the primary producer communities in the short term (three years). Our work substantiates the pivotal role played by fragmentation and hydrology, in addition to groundwater, in structuring riverine macrophyte communities. Further investigations are needed to resolve the uncertainty surrounding the non-linear responses of macrophytes to the physical and chemical conditions of rivers.

Mitochondrial evidence supports a Nearctic origin for the spreading limicolous earthworm Sparganophilus tamesis Benham, 1892 (Clitellata, Sparganophilidae)

We analysed samples of Sparganophilus taken at the corners of its distribution area in Europe (UK, Germany and Italy). No mitochondrial genetic divergence within and amongst them was found, neither in COI nor in 16S. Further, the COI haplotype was also identical to two sequences from Ontario, Canada in the Barcoding of Life Data System (BOLD) database. Our European COI and 16S sequences showed only minimal differentiation (only 1 or 2 substitutions) from specimens newly collected in Illinois and Washington states (USA), as well as from a COI haplotype from Tennessee (USA) in BOLD. An additional COI haplotype from Illinois (found in BOLD) is 2.1% different from the other haplotypes but clearly belongs to the same lineage of Sparganophilus . This geographically broad but genetically compact group fits the morphological diagnosis of S. tamesis Benham, 1892 as revised by Jamieson (1971) and is seen as evidence that all European populations 1) belong to the same species, 2) derive from a recent introduction, 3) are conspecific with the most widespread species of Sparganophilus in North America, and that 4) S. tamesis is a senior synonym of S. eiseni Smith, 1895. The single European haplotype does not refute the possibility of its spread from a single introduced source population.

Avoiding social traps in the ecosystem stewardship: The Italian Fontanile lowland spring

Fontanile is a Po Valley (Italy) quasi-natural lowland spring built in the middle age. This paper identifies options for the conservation of the Fontanile water dependent ecosystem, using scenarios and simulations, and exploring different policy options. Three modeling analysis have been performed: the first was carried out for estimating groundwater contamination and recharge from above, the second for evaluating the function of vegetative filter strip on the surface water quality and the last one for testing pesticide drift reduction due to the vegetative filter strip. Uncertainty characterization included climate change projections. Despite the nitrate concentration in water could favorite the eutrophication phenomena, this not occurs because of the low phosphate concentration in water and of the presence of arboreal shade. Therefore, the protection strategies must focus on sustaining desirable water quantity conditions. Water saving and conservation technologies that improve the agricultural productivity but reduce the Fontanile water flow and large buffer strips that have a limited efficacy due to the Fontanile hydrological settings can be judged as ecological traps. Inefficient irrigation systems, good agricultural practices, integrated pest management and arboreal filter strip can preserve the quality of those ecosystems.

Herbicide contamination and dispersion pattern in lowland springs

Herbicides reduce the diversity of flora and fauna in freshwater ecosystems and also contaminate groundwater due to leaching. Herbicide contamination can be a serious threat for all groundwater-dependent ecosystems (GDE), altering their chemical and biological quality. Successful management to protect GDE is dependent on detailed knowledge of the hydrogeological and hydrochemical features of the surrounding environment. We consider the possible diffuse contamination by herbicides of groundwater and of GDE as lowland springs, semi-artificial ecosystems with elevated biodiversity. The main objectives of the present work were thus: (1) to map herbicide contamination in lowland springs, (2) to evaluate the potential risk for biota and (3) to quantify the extent of the area from which the herbicide use can affect the water quality of lowland springs. In June and August 2009, nearly 23 springs within the Po River Plain (Northern Italy) were sampled and analyzed for five herbicides used to control weeds in maize. Hydrogeological properties, half-lives of the herbicides and their concentrations in both groundwater and springs were used to quantify the area from which the contamination could originate. Such evaluation was performed by means of GIS techniques. Terbuthylazine were the only herbicide found, together with its metabolite desethylterbuthylazine. In 16 out of 84 measurements, their concentrations were above the threshold for drinking water; however, they were always below the ecotoxicological end-points of aquatic flora and fauna. Spatial analyses reveal that the theoretical area from which herbicides can contaminate spring water is within a distance varying between a few and 1800 m. Our findings indicate that conservation plans should focus on the fields adjacent to or surrounding the springs and should address the optimization of irrigation practices, restoration of buffer strips, crop rotation and in general more sustainable agricultural practices in the proximity of these fragile GDE.