Francesca Bona

Diatom teratological forms and environmental alterations: a review

The foremost feature of a diatom is the species-specific ornamentation of the silicon cell wall, which is preserved and faithfully reproduced through the generations. If exposed to different kinds of stress during reproductive processes, the diatom cell outline and striation pattern can change in different ways, producing teratological forms. These modifications can be slight, leading to difficulties in establishing a threshold between normal and teratological cells, or so marked that it is very difficult to recognize whether an unknown form is teratological or whether it belongs to a new species or variety. Teratological forms appear as an accidental effect of environmental stresses, which can be both physical and chemical. Artificial conditions also often lead to the development of teratological forms. Most frequently, diatoms present abnormal valve outline (lack of symmetry, bent, incised, swollen, or notched profile), unusual raphe system (fragmented, displaced, and bifurcated), abnormal striation pattern (irregular, altered, fragmented, and branched), and unusual raphe channel system (distorted, curved, and occasionally doubled back). In this review we analyzed 222 articles, published from 1890 up to 2008, with the aim to correlate the abnormal diatom cell morphology to environmental alterations, in a perspective which can greatly enhance the evaluation of river environmental quality for biomonitoring purposes.

Growth of three microalgae strains and nutrient removal from an agro-zootechnical digestate

In this paper three microalgae strains (Neochloris oleoabundans, Chlorella vulgaris and Scenedesmus obliquus) were cultivated on an agro-zootechnical digestate in comparable conditions. The material used as growth media was obtained from a pilot plant anaerobic digestor used to digest several mixes of cattle slurry and raw cheese whey. The main aims were to compare the algae growth, their tolerance with respect to the various dilutions of digestate, their nutrient removal efficiency and their role in the transformation of nitrogen compounds. C. vulgaris presented the highest elimination capacity of ammonium in 1:10 digestate sample; it was also observed that only 4% of ammonia was removed with stripping, microalgal and bacterial consortium recovered the remaining 96%. The three strains almost completely removed different nitrogen forms and phosphate in 11d. The results show that microalgal biomass production offers real opportunities for addressing issues such CO2 sequestration, biofuel production and wastewater treatment.

Influence of Landscape Diversity and Agricultural Practices on Spider Assemblage in Italian Vineyards of Langa Astigiana (Northwest Italy)

Abstract The purpose of this study was to investigate spider assemblages of the Italian vineyards of Langa Astigiana (northwest Italy). Pitfall trapping and standardized hand collecting were combined to have an overall idea of the spider fauna living in this agroecosystem. A total of 138 samples for pitfall sampling and 92 for hand collecting sites were collected at 23 different times over a period of 2 yr (2003 and 2004). The vineyards differ mainly from agricultural practices (certified organic production, production according to EEC’s Council Regulation 2092/91 on biological agriculture and intensive production) and for the heterogeneity of landscape matrix surrounding them. We studied the influence of these two factors on spider assemblages applying canonical correspondence analysis and multiresponse permutation procedures (MRPPs). Significant results of MRPP were analyzed in terms of hunting strategies. Significant differences are found among groups according to both landscape heterogeneity and agricultural practices, the first resulting more significantly. Analyzed in terms of hunting strategies, an increase in landscape heterogeneity seems to provide an increase in ambush spiders and specialized predators, whereas an increase in sheet web weavers seems to be related to homogeneous landscapes.

Characterization of diatom assemblages in mid-altitude streams of NW Italy

Following the European Water Framework Directive, this study aims to be the first step to (i) identify diatom type assemblages in unpolluted streams in NW Italy, and (ii) find which ecological factors explain most of the variation. To achieve this, we collected physical, chemical and benthic community data from four streams in NW Italy from 2001 to 2004, for a total of 72 samples. All sampling sites were between 200 m a.s.l. and 800 m a.s.l., but differed in the dominant lithological substrate, i.e. alluvial or siliceous. Relationships between diatom communities and environmental factors were examined using canonical correspondence analysis (CCA), while Indicator Species Analysis was used to define characterizing species and accompanying species of three environmental groups identified by CCA: (1) high water quality and medium saline content, (2) high water quality and low saline content, (3) poor water quality. The diatom assemblages of the three groups of sites differed significantly, as shown by the Multi-Response Permutation Procedure. There were strong correlations between diatoms and environmental factors, especially chlorides (also highly correlated with sulphates and carbonate hardness), nitrate concentration and conductivity. The group 1 assemblage was typical of the alluvial Alpine streams with medium saline content and was characterized by mostly oligosaprobic/β-mesosaprobic taxa such as Cymbella affinis, Diatoma ehrenbergii and Staurosira pinnata. The species assemblage found in the siliceous Alpine rivers with good water quality make them suitable reference sites for a benthic diatom community.

Monitoring crayfish using a mark-recapture method: potentials, recommendations, and limitations

Crayfish are regarded as useful indicators of environmental quality and freshwater biodiversity. However, reliable methods for monitoring their populations are needed so that this potential can be fully utilised. We report and discuss methodological aspects of the white-clawed crayfish (Austropotamobius pallipes complex) survey conducted in Piedmont, Italy, with the use of mark-recapture. The results suggest that the method can serve as a convenient tool for estimating the size of crayfish populations and inferring their temporal trends. The two populations investigated appeared closed except for wintertime and July. Consequently, the Robust Design, which is regarded as the most reliable mark-recapture approach, can be easily applied. The minimum effective sampling plan for monitoring purposes should comprise one primary period per year, conducted in the summer–autumn season, and consisting of three capture sessions. If gaining insight into the ecology of the investigated species is the prime objective and sufficient resources are available, the optimal plan should include two primary periods (in spring and the summer–autumn season) of five capture sessions each. Capture sessions need to be separated by roughly 2-week intervals in order to avoid the strong, but short-term, negative effect of capturing crayfish on their recapture chances. As the model without heterogeneity in capture probabilities ensures better estimate precision we recommend that data collected for both sexes are analysed separately. Taking into consideration higher male catchabilities and sex ratio being invariably 1:1, it also seems beneficial to estimate only male numbers and double them to achieve total population sizes.

Where do we go from here? Dispersal simulations shed light on the role of landscape structure in determining animal redistribution after reintroduction

Reintroduction projects represent viable options for animal conservation. They allow the establishment of new local populations and may contribute to recreating functional networks within a metapopulation. In the latter case, landscape connectivity may be a major determinant of the phase of spread of the reintroduced populations. Here, we deal with an example of a red deer (Cervus elaphus) translocation planned to enable the connection among existing isolated populations of the species in the Italian Alps. Our aim was to assess whether the analysis of landscape suitability and the simulation of dispersal of released individuals could shed light on the actual process of population spread. For these purposes, we adopted a modelling approach using radiotracking data to develop a habitat suitability map. On the basis of this map, we simulated the dispersal of the animals after release and we then compared the simulation results with the outcome of null models and with the observed population redistribution. The results suggest that the spread of the subpopulation was easier north-westward than southward. Taking into account landscape suitability, our simulations produced a reliable estimate of the ease of colonization of the valleys neighbouring the release-site and they allowed the identification and validation of a potential pathway for animal dispersal. The suitability model based on the monitoring of individuals in the earliest phase of establishment shed light on the spread of the population and on its potential connections with other deer subpopulations.

Is digestate safe? A study on its ecotoxicity and environmental risk on a pig manure

Digestate represents a precious by-product in particular in agriculture, however its impact on the environment and human health is still unexplored. In this work, the toxicity of a pig slurry digestate was assessed through 7 ecotoxicity tests and considering 10 different endpoints. Besides, a synthetic index was applied to the outputs of the battery of tests for the environmental risk assessment, in order to evaluate the opportunity to use directly this kind of digestate in agriculture or to introduce an additional treatment. All the organisms were sensitive to digestate toxicity (EC50 ranged from 14.22% for Cucumissativus to 0.77% for Raphidocelis subcapitata). The physical-chemical features at the base of this toxicity seem to be the high content of ammonium, salinity, COD, phosphate and colour. The synthetic index showed that the digestate was very toxic and associated to an extremely high environmental risk. Thus, a pre-treatment is needed to reduce its toxicity and environmental impact, whatever could be its exploitation.

Comparison of Polyethylene Bubble Wrap and Corrugated Cardboard Traps for Sampling Tree-Inhabiting Spiders

Abstract In this paper, we studied the use of polyethylene bubble wrap and corrugated cardboard bark traps to sample spiders inhabiting tree trunks, with special reference to test whether they function the same way despite the differences in the spider community imposed by the different tree species and surroundings and times of sampling. The survey was carried out from July 1997 to July 1998 in Turin, Italy, in a green urban area on three poplars and four American basswoods. Differences between the two methods were tested in terms of abundance, diversity, dominance, mean body length of specimens, and proportion of juveniles, calculating Spearman’s correlations. Three-factor analysis of variance, multiresponse permutation procedure, and indicator species analysis were used for further analysis. Results obtained by the two traps were correlated following a similar trend over sampling time. Bubble polyethylene seemed to be more effective than corrugated cardboard at trapping higher number of specimens. The dimension and total amount of interstices and the different microhabitat conditions of temperature and humidity seemed to be the main factors influencing spider composition in terms of the selected variables. On the basis of our results, polyethylene bark traps are recommended for sampling spiders living on trees. It is important to consider seasonality in experimental design, autumn being the period with the highest abundance of spiders but a lower level of diversity.

Alpine freshwater ecosystems in a protected area: a source of diatom diversity

The “All Taxa Biodiversity Inventories” (ATBIs) project coordinated by the European Distributed Institute of Taxonomy (EDIT) aims to achieve a baseline biodiversity assessment of flora and fauna in those regions characterized by a lack of knowledge and a high potential for biodiversity. Within the framework of the ATBIs, the aim of this study was to analyse the diatom flora and ecology of a complex of freshwater ecosystems in the Maritime Alps Natural Park (Italy), designated as a Special area of Conservation under the European Habitat Directive. We sampled epilithic and epiphytic diatoms in different habitats in 24 sites: shallow lake, springs, and streams. Our analysis resulted in a list of 138 diatom taxa, highlighting the great biodiversity and the complex structure of the investigated diatom communities. The taxa list included a wide range of uncommon species, including some recorded for the first time in North-Western Italy. Among the different habitats the highest level of diversity was found in the more lentic waters, in particular in limnocrene springs. These results show that the diatom communities of pristine and undisturbed high-mountain environments are rich and complex, despite the severe environmental conditions.

Diatom flora in subterranean ecosystems: a review

*elisa.falasco@unito.it abundance and diversity of organisms (Holsinger, 1998) and the abiotic conditions at the deeper parts of the caves are generally more stable. In the absence of light and primary producers, cave habitats are generally extremely oligotrophic, receiving poor supplies of degradable organic matter. They rely almost exclusively on organic matter from surface habitats (Poulson & Lavoie, 2000). Primary source of energy is generally decaying organic matter deriving from plants, guano and carrion (Braack, 1989), whose bioavailability is largely dependent on its chemical properties and on environmental physical factors, such as temperature and light (Smith & Benner, 2005). THE SUBTERRANEAN ENVIRONMENT