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We studied hydrochemistry and plankton dynamics in two remote alpine lakes: lake Nivolet superiore (2530 m asl) and lake Trebecchi superiore (2729 m asl) in the Gran Paradiso National Park (Western Italian Alps) in summer 2009. The aim of this study was to enhance the understanding of natural ecological dynamics in the pelagic habitat of alpine lakes by enlarging the number of biotic and abiotic variables usually considered to this end and by increasing the frequency of samplings, generally low in remote lakes. During the eight samplings performed in 2009, chemical and physical variables were measured both in situ and in the laboratory. We also followed the dynamics of all the compartments of the naturally simplified trophic chain of the two lakes from pico-prokaryotes to phytoplankton and zooplankton. Our results confirm the oligotrophic, close-to-pristine state of lake Nivolet and lake Trebecchi as they are not affected by hydromorphological alterations, they are naturally fishless and are not sensitive to acidification risk and acidity pulses. On the other hand, the two lakes have distinct abiotic conditions due to their glacial origin and to the lithological composition of their watersheds. We found some differences in the spatial variation of pico-prokaryotes, phytoplankton and zooplankton due to the different mixing regimes and maximum depth of the two lakes. Conversely, temporal patterns were similar in both lakes, related to ecological interactions and to changes in the abiotic conditions. The rapid succession of events in extreme ecosystems, such as the alpine lakes studied here, confirm the predominant role of external environmental factors (e.g. the duration of the ice-free season) and of ecological interactions among different trophic compartments. This research underlines the importance of seasonal niche partitioning among organisms with different size.

We present a data set on the biodiversity of Italian freshwaters, including lakeshores and riverbanks of natural (N=379: springs, streams and lakes) and artificial (N=11: fountains) sites. The data set belongs partly to the Italian Long Term Ecological Research network (LTER-Italy) and partly to LifeWatch, the European e-Science infrastructure for biodiversity and ecosystem research. The data included cover a time period corresponding to the last fifty years (1962-2014). They span a large number of taxa from prokaryotes and unicellular eukaryotes to vertebrates and plants, including taxa linked to the aquatic habitat in at least part of their life cycles (like immature stages of insects, amphibians, birds and vascular plants). The data set consists of 6463 occurrence data and distribution records for 1738 species. The complete data set is available in csv file format via the LifeWatch Service Centre.

We publish a dataset on planktic and benthic diatom occurrence in Lake Maggiore, the second Italian lake for depth and surface. Despite their extensive use in water quality biomonitoring, and their relevance among phytoplankton groups, research on benthic diatoms in Lake Maggiore are scarce. Diatoms have been collected from surface sediments, littoral stones, macrophytes and water column, in different times and with different purposes during the last 40 years of the trophic history of the lake. Dataset includes 4124 occurrences relating to 293 taxa, 269 of which were identified at species level, 16 at subspecies level and 8 at the genus level. All occurrences are georeferenced. [ABSTRACT FROM AUTHOR]

We report a georeferenced dataset of a biological survey carried out in lakes and reservoirs in Piedmont and Sardinia regions (Italy), that includes fish fauna, macroinvertebrates, macrophytes, and phytoplankton. This survey was carried out to test the standardised protocols adopted with the National Decree 260/210 by the Italian Ministry of the Environment, Land and Sea for the assessment of the ecological status of lakes and the ecological potential of reservoirs for satisfying the requirements of the European Water Framework Directive (WFD) 2000/60/EC. Occurrence data have been uploaded to the Global Biodiversity Information Facility (GBIF). [ABSTRACT FROM AUTHOR]

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1365-2745.2007.01240.x Byline: DANIELE COLOMBAROLI, ALDO MARCHETTO, WILLY TINNER Keywords: Abies alba; climate warming; coastal marshlands; diatoms; Holocene; fire ecology; Mediterranean; Quercus ilex Abstract: Summary A Holocene sedimentary sequence from a coastal lake in the Mediterranean area (Lago di Massaciuccoli, Tuscany, Italy, 0 m a.s.l.) was sampled for pollen and microscopic charcoal analyses. Contiguous 1-cm samples represent an estimated time interval of c. 13 years, thus providing a high-resolution sequence from 6100 to 5400 cal. years bp. Just before 6000 cal. years bp, sub-Mediterranean and Mediterranean forests were present together with fir (Abies alba), a submontane species that is today absent at low altitudes in the Mediterranean. A sharp vegetational change occurred after 6000 cal. years bp involving a drastic decline of Abies alba around the site. Time-series analyses suggest that increased fire activity at this time caused a strong decline in Abies alba, a highly fire-sensitive species. During 100 years of higher fire incidence, diverse (predominantly evergreen) forest communities were converted to low-diversity fire-prone shrub communities. Cross-correlations reveal that fire during the mid-Holocene hindered the expansion of holm oak (Quercus ilex), the most common tree species today in Mediterranean environments. While the factors that triggered the Holocene expansion of this species in the Mediterranean area are unclear, our results do not support the hypothesis that fire was key for holm oak expansion. Diatom analyses of the same sediment core provide an independent palaeoenvironmental proxy for palaeoclimatic reconstruction. A change in the eutrophy and salinity of the lake occurred just before 6000 cal. years bp, suggesting that a climatic shift towards aridity may have triggered the observed change in hydrology and possibly also in fire regime. Over the millennia fire has decisively contributed to the establishment of the present fire-adapted vegetation type (macchia). Native fire-sensitive species were displaced or repressed, and arboreal vegetation became less diverse. Combined ecological and palaeoecological data may help to assess possible future scenarios of biosphere responses to global change. Our results imply that the forecasted global warming and fire increase may trigger irrecoverable biodiversity losses and shifts in vegetational composition within a few decades or centuries at most. In particular, fire and drought-sensitive vegetation types, such as the relict forests of Abies alba in the Apennines, seem particularly threatened by large-scale displacement. Article History: Received 13 September 2006; revision accepted 1 March 2007 Editor: Peter Moore Article note: Correspondence: Daniele Colombaroli (e-mail daniele.colombaroli@ips.unibe.ch).