Search

The definition of relationships among the attributes of macroinvertebrate communities and environmental gradients is fundamental to understand ecological dynamics. Testing the response of macroinvertebrate communities and the related metrics to the action of multiple drivers is crucial to provide reliable tools for the management and conservation of freshwater ecosystems. In this study habitat conditions, seasons and physical–chemical water characteristics were evaluated as potential limiting factors for macroinvertebrate communities. 42 sites, along 11 pre-Alpine rivers and streams, were surveyed for macroinvertebrate communities and water chemistry, collecting a total of 387 samples. Hydromorphological characteristics and habitat availability in each sampling site were assessed to describe different features of channel, banks and vegetation that can be relevant for management purposes. Macroinvertebrate community characteristics were summarized by both structural metrics (i.e. density, diversity and taxonomy-based) and ecosystem attributes derived from functional trait analysis. Functional traits are based on morphological and behavioural attributes associated with feeding, modes of attachment, concealment and locomotion, together with voltinism and drift propensity. In this framework, quantitative models have been developed to predict the potential characteristics of macroinvertebrate communities as a function of selected environmental variables. These relationships can be used to predict the effects of river restoration programs on macroinvertebrate diversity and ecosystem processes.The various metrics considered in this study may help to raise a better awareness in the natural functioning of river ecosystems, the selection of effective strategies for the conservation of biological communities, and the evaluation of river restoration success, thus supporting decision-making processes.

The correct definition of ecosystem needs is essential in order to guide policy and management strategies to optimize the increasing use of freshwater by human activities. Commonly, the assessment of the optimal or minimum flow rates needed to preserve ecosystem functionality has been done by habitat-based models that define a relationship between in-stream flow and habitat availability for various species of fish. We propose a new approach for the identification of optimal flows using the limiting factor approach and the evaluation of basic ecological relationships, considering the appropriate spatial scale for different organisms. We developed density-environment relationships for three different life stages of brown trout that show the limiting effects of hydromorphological variables at habitat scale. In our analyses, we found that the factors limiting the densities of trout were water velocity, substrate characteristics and refugia availability. For all the life stages, the selected models considered simultaneously two variables and implied that higher velocities provided a less suitable habitat, regardless of other physical characteristics and with different patterns. We used these relationships within habitat based models in order to select a range of flows that preserve most of the physical habitat for all the life stages. We also estimated the effect of varying discharge flows on macroinvertebrate biomass and used the obtained results to identify an optimal flow maximizing habitat and prey availability.

The impact of prospective climate change on the hydrological and ecological status of the mountain stretch of the Serio river (ca. 300 km2) in the Northern Italian Alps was investigated. A hydrological model was used to mimic theflow regime, and experimental suitability curves were used to assess weighted usable area (WUA) for brown trout ( Salmo trutta ) in different stages (adult, young, and spawning), and four macroinvertebrates families ( Leuctridae, Heptageniidae, Limnephilidae, and Limoniidae ). Discharge-WUA curves were obtained using instream flow incremental methodology/physical habitat simulation system (IFIM-PHABSIM), and a seasonal WUA assessment was carried out. The future (until 2100) hydrological cycle was projected using outputs from two general circulation models from Assessment Report 5 of the Intergovernmental Panel on Climate Change (IPCC). The results display a potential for a large flow decrease yearly, until -60% at 2050 and -56% at 2090. Spring melt peaks will be largely dampened, with the largest projected decrease of -60% in 2050 and -66% in 2090. Also fall flows will be largely smoothed, down to -70% for 2050 and -56% for 2090. To quantify habitat quality, a specific quantile WUA20%, was used and exceeded presently for 292 days in a year, and the percentage of critical days nc% when WUA < WUA20%. Adult trouts will have decreasing nc% yearly (from 20% now to down to 13% in 2090), increasing in winter and spring and decreasing in fall. Young trouts will have decreasing nc% yearly (from 20% now to down to 2% in 2040 and 2090), but increasing in winter. Spawning, occurring in winter, will have lower nc% (from 16% now, to down to 8% in 2090). Macroinvertebrate families will have constant nc% yearly, unless for Leuctridae (from 20% now to up to 38% in 2050), and noticeable decrease of nc% in winter for Leuctridae until 2090, increase in spring and summer, and decrease in fall for all families until 2090. Correlation analysis of the WUA against w

Constructed wetlands play an important role in water supply, floodwater retention and nutrient removal, at the same time allowing the restoration of lost habitat and the preservation of biodiversity. There is little knowledge about the biodiversity that can be found in these artificial environments along time, especially at the invertebrate community level. Macroinvertebrate assemblages, water chemistry, morphology, and environmental characteristics of natural ponds, artificial pools and constructed wetlands in Parco Pineta (Northern Italy) were studied to evaluate the effects of local factors on macroinvertebrate communities. The objective was to verify if each ecosystem could equally contribute to local biodiversity, regardless of its natural or artificial origin. Principal Components Analysis showed that ponds were divided into clusters, based on their morphology and their water quality, independently from their origin. The composition of macroinvertebrate communities was similar among natural wetlands and ponds artificially created to provide new habitats in the park, while it was different among natural wetlands and constructed wetlands created for wastewater treatment purposes. Biodiversity of natural ponds and constructed wetlands, evaluated using taxa richness, Shannon index, and Pielou index, was comparable. Canonical Correspondence Analysis highlighted differences in macroinvertebrate community composition and pointed out the relationships among macroinvertebrates and various environmental variables: habitat heterogeneity resulted as the most relevant factor that influences taxa richness. Water quality also affects the macroinvertebrate community structure. We determined that constructed wetlands with higher pollutant concentrations show different assemblage compositions but comparable overall macroinvertebrate biodiversity. Constructed wetlands became valuable ecological elements in the area almost immediately, due to fast colonizing invertebrates. Howeve

A series of experimental tests has been conducted to investigate the efficiency and the by-product generation of high dose ozonation (10 to 60 mg O3 L-1) for complete colour removal from a treated effluent with an important component of textile dyeing wastewater. The effluent is discharged into an effluent-dominated stream where no dilution takes place, and thus, the quality requirement for the effluents is particularly strict. Three contact times were adopted: 30, 60 and 90 min. Colour was measured as absorbance at 426, 558 and 660 nm wavelengths. The experimental work showed that at 50 mg L-1 colour removal was complete and at 60 mg O3 L-1 the final aldehyde concentration ranged between 0.72 and 1.02 mg L-1. Glyoxal and methylglyoxal concentrations were directly related to colour removal, whereas formaldehyde, acetaldehyde, acetone and acrolein were not. Thus, the extent of colour removal can be used to predict the increase in glyoxal and methylglyoxal concentrations. As colour removal can be assessed by a simple absorbance measurement, in contrast to the analysis of specific carbonyl compounds, which is much longer and complex, the possibility of using colour removal as an indicator for predicting the toxic potential of ozone by-products for textile effluents is of great value

The presence of different kinds of leaf packs (native or alien) and environmental gradients can affect the composition and abundance of macroinvertebrate assemblages in fresh water ecosystems,but little is known about the interactive effects. Here, we investigated (1) how environmental gradients could influence leaf packs macroinvertebrates and (2) which was the chief factor (among water quality, mass loss of leaf packs, and flow regime) affecting macroinvertebrate assemblages in impaired streams. We analyzed leaf packs in six sites in impaired streams, characterized by waste water discharges and dominated by pollution-tolerant macroinvertebrate species. Using principal component analysis, we defined two environmental gradients as follows: a water quality gradient,related to anthropogenic alteration, and a hydromorphological gradient, mostly related to the catchment features. Our results pointed out that, in the tested conditions, biological metrics, such as functional groups and taxa richness, were chiefly influenced by the water quality gradient, while different leaf types in packs influenced the total taxa richness, but did not cause significant variation in the distribution and abundance of macroinvertebrate functional groups. On the contrary, the mass loss differed for different leaf types and was related to the stream and catchment features (mainly flow). This work showed that, in impaired streams, macroinvertebrate assemblages colonizing leaf packs are more influenced by water quality than by leaf types. Thus, the improvement of waterquality should be the priority in restoration programs and should be achieved before any effort to restore native riparian vegetation

The Lambro-Seveso-Olona (L-S-O) system derives from the human regulation of the natural hydrology of the territory around Milan city area. The average population density in the L-S-O area is among the highest in Italy and Europe. Industry is also highly developed in this basin: chemical, textile, paper, pulp and food industries being the most important ones. Although, at present, the L-S-O system no longer receives the untreated wastewaters of the Milan urban area, treated wastewaters constitute about half of the streamflow. Biotic communities in this river have a long history of poor quality status, having suffered great damage due to domestic and industrial discharges. Recently, new chemical quality standards for macropollutants have been set by the Italian legislation as support for the good ecological status according to the Water Framework Directive (WFD). This new index is very restrictive, and it makes it extremely challenging to achieve the water quality objectives for the L-S-O system. The aim of this study is to analyse through a modelling exercise the restoration possibilities of the L-S-O system, investigating both the source apportionment of the macropollutants, the discharge limits that should be set to achieve the good quality status and their corresponding cost

Benthic macroinvertebrates are widely used as indicators of the health of freshwater ecosystems, responding both to water quality and to the hydromorphological integrity. In urban streams, evaluations can be tricky for the synergistic effects of multiple stressors and confounding factors. In these situations, the most broadly used multimetric indices can be used to assess the overall damage to the invertebrate community and, thus, the overall anthropogenic pressure, but they do not allow to understand the specific causal effects. Particularly, habitat loss due to morphological alterations can be difficult to evaluate, especially due to the often concurrent disturbance caused by water pollution. We used a multivariate approach to focus on the characteristics of the streams and rivers in an urban district and to define which macroinvertebrate metrics should be used to assess the influence of the different kinds of alteration in a severely damaged environment. Some metrics enabling the assessment of habitat loss (ratio of oligochaeta, ratio of filterers) were identified. These metrics may help to raise a better awareness in the evaluation of river restoration success and, thus, in the support of decision-making processes

Contamination of drinking water is a major issue in depressed areas, especially in developing countries. Moreover, in such areas suitable conditions for the determination of E. coli using standard count plate methods could be missing. The level of water contamination and the operational conditions of a city in the Democratic Republic of the Congo were analyzed, and subsequently recreated in laboratory. We tested the efficacy of three fast E. coli detection methods in both optimal and operational conditions, and compared them to standard methods. The results showed that there were no significant differences between the various methods in the different conditions. Thus, fast methods can successfully be used, although a tendency to produce false negatives with low levels of contaminations should be taken in account.

Uno degli elementi critici per una migliore comprensione delle dinamiche ecosistemiche in fiumi e torrenti fortemente modificati e per i processi decisionali relativi ai programmi di riqualificazione fluviale è l’individuazione di quali fattori pongano limiti al corretto sviluppo delle comunità biologiche in una situazione caratterizzata da alterazioni multiple. In particolare, i corpi idrici fortemente modificati che attraversano ambienti urbani o, comunque, di notevole antropizzazione subiscono gli effetti congiunti e sinergici di deterioramenti relativi alla qualità delle acque, al regime idraulico e alla morfologia fluviale. In queste situazioni, è molto spesso difficoltoso definire relazioni causali tra alterazioni specifiche e le risposte delle comunità biologiche usando gli strumenti del biomonitoraggio o i più comuni strumenti statistici quali la regressione lineare. Tali strumenti consentono per lo più la verifica di ipotesi relative alla tendenza centrale dei dati, definendo ad esempio la relazione media tra una metrica biologica e una variabile ambientale. In presenza di alterazioni multiple, tuttavia, il “rumore di fondo” introdotto dalla presenza simultanea dei deterioramenti in vari ambiti della funzionalità fluviale può compromettere la validità di tali tipologie di modelli, fino a renderli non informativi. La distribuzione dei valori delle metriche biologiche lungo gradienti specifici di alterazione assume l’aspetto di “nuvole” di dati apparentemente caotiche. L’uso della regressione quantile, tuttavia, permette di valutare le singole alterazioni come fattori limitanti allo sviluppo delle comunità biologiche, individuando così la relazione causale tra esse. Nell’ambito del Progetto FIUMI, nato dalla collaborazione tra Regione Lombardia, ARPA Lombardia e due atenei lombardi, e in vista della progettazione di interventi di riqualificazione fluviale nel bacino Olona-Lambro, uno dei più fortemente modificati d’Italia, sono state analizzate le relazioni t

The paper reports the results of comparative trials carried out at demonstrative and pilot scale using constructed wetlands for the final polishing of treated effluents (ozonated and non ozonated) which are discharged into a small stream, often dry, whose flow is chiefly made of the effluents themselves. The effluents fed to experimental constructed wetlands had comparable quality for the chief parameters. The removal percent was higher in the case of ozonated effluents for total phosphorus and total nitrogen, especially due to the higher concentration of oxygen, while COD and TSS reval were comparable in the two cases.

On February 23rd 2010, several thousand tons of fuel oil and other hydrocarbons were poured into the sewerage system of Villasanta (MB), causing the spill of about 3000 m3 of them into the Lambro River and the interruption of the purification activities at the local Wastewater Treatment Plant (WWTP). The effects on the benthic invertebrate communities were analyzed, comparing data collected before and after the accident. The lack of detail of the data collected before the spill and the concurrent presence of various stressors led to the necessity of more detailed analyses, based on a experimental design built over space (upstream and downstream the spill). The ANCOVA and multivariate analysis of the shifts occurred to several diversity, taxonomical and functional metrics in macroinvertebrate assemblages at microhabitat level allowed identifying effects due to the pre-existent impairment, the spill of untreated wastewater, and the oil. The de-oxygenation of water due to the WWTP breakdown affected the taxa richness and caused the disappearance of the most specialized functional groups (e.g. filterers and grazers), especially in riffle areas. The deposition of oil in finer sediments resulted in a considerable reduction of densities in tolerant taxa, thus, paradoxically, increasing Shannon Index values in samples collected downstream the spill. Overall, the greatest short-term damage to invertebrate biodiversity seemed to be caused by the spill of untreated wastewater.

The introduction of artificial ponds is a restoration measure to compensate for wetland habitat loss, but a deeper knowledge of the ecological relationships in these environments is needed. Aim of this work has been to enlighten the differences in macroinvertebrate assemblages in artificial and natural ponds, and to consider the relative importance of several variables in explaining the functional and trophic patterns in each ecosystem. The ultimate purpose has been to gain information about the potential role of artificial ponds in ecological networks. Within Parco Pineta, a regional park in Lombardia, numerous ponds and wetlands are present. 24 of them have been chosen to analyse differences in invertebrate biodiversity. They are natural (16) and artificial (8) ecosystems, two of the latter being part of a constructed wetland system created for wastewater treatment. Environmental characteristics of each pond and taxonomic composition of macroinvertebrates have been monitored. Significant (a=0.05) differences were not found in biodiversity among different wetland typologies. Univariate and multivariate statistics showed that the most significant environmental factors related to community composition were water body area and microhabitat heterogeneity, while water quality seemed to have scarce influence. The presence of fish could be identified as a limiting factor. Further analyses have been carried out involving macroinvertebrate dispersion strategies and functional feeding groups in order to evaluate ecological behaviours and trophic web organization in the different kinds of wetlands