Marco Cantonati

Climate change and nutrient pollution are echoed by worldwide increasing trends in the frequency, duration, and toxicity of cyanobacterial (blue-green algal) blooms. Therefore, searching for the best options to mitigate blooms is relevant and timely. Aquatic vascular plants offer a promising solution through biological control. In this study, we use reservoirs regularly affected by intensive blooms (the Kyiv and Kaniv Reservoirs of the Dnipro River, Ukraine) to investigate whether macrophytes may inhibit or reduce the massive development of cyanobacteria. Special attention was paid to plants with floating leaves and free-floating plants since data on their effects on cyanobacteria are controversial. On the basis of field and satellite observations, the spatial distribution of cyanobacterial blooms and aquatic macrophyte patches was assessed. Multispectral images captured by satellites Sentinel-2a (S2A) and Sentinel-2b (S2B) were used. In addition, based on data from field observatio...

The species–area relationship (SAR) is one of the most distinctive biogeographic patterns, but global comparisons of the SARs between island and mainland are lacking for microbial taxa. Here, we explore whether the form of the SAR and the drivers of species richness, including area, environmental heterogeneity, climate and physico‐chemistry, differ between islands and similarly sized areas on mainland, referred to as continental area equivalents (CAEs). Global. Stream benthic diatoms. We generated CAEs on six continental datasets and examined the SARs of CAEs and islands (ISAR). Then, we compared CAEs and islands in terms of total richness and richness of different ecological guilds. We tested the factors contributing to richness in islands and CAEs with regressions. We used structural equation models to determine the effects of area versus environmental heterogeneity, climate and local conditions on species richness. We found a non‐significant ISAR, but a significant positive SAR in CAEs. Richness in islands was related to productivity. Richness in CAEs was mainly dependent on area and climate, but not directly on environmental heterogeneity. Species richness within guilds exhibited inconsistent relationships with island isolation and area. Ecological and evolutionary processes shaping diatom island biogeography do not depend on area at the worldwide scale probably due to the presence of distinct species pool across islands. Conversely, area was an important driver of diatom richness in continents, and this effect could be attributed to dispersal. Continents had greater richness than islands, but this was a consequence of differences in environmental conditions such as specific island climatic conditions. We stress the need for more island data on benthic diatoms, particularly from archipelagos, to better understand the biogeography of this most speciose group of algae.

In July 2017, Lange-Bertalot et al. (2017) published a revised and translated version of Hofmann et al. (2013)’s book on freshwater benthic diatoms of Central Europe. The revised edition includes a few nomenclatural novelties which neither conform to the Melbourne Code (McNeill et al. 2012) nor to the upcoming Shenzhen Code (see Turland et al. 2017). The treatment of Tryblionella gracilis W.Sm. and T. hantzschiana Grunow shows how nomenclatural and taxonomic data can sometimes be confusing. This paper validates five names invalidly published in Lange-Bertalot et al. (2017) whilst the valid but previously neglected name T. hantzschiana is proposed to replace Tryblionella tryblio Cantonati et Lange-Bert., nom. inval. The registration numbers refer to PhycoBank (Kusber et al. 2017) a registration system on algae (Barkworth et al. 2016) which recently went online.

Sampling campaigns associated with the ongoing PhyBiO project revealed the new presence of the benthic pinnate heterovalvar araphid diatom Licmophora normaniana. This species is considered cosmopolitan and is common on marine coasts. Based on literature searches, the following identification represents the first known occurrence in an inland mineral spring in the Siwa Oasis, the Western Desert of Egypt, and of this diatom species in mineral desert springs generally, or from any inland waterbody. The presence of L. normaniana was confirmed using light and scanning electron microscopy. Environmental variables (including major ions and metals) of this Saharan biotope were measured to characterize the habitat of this population. We hypothesize that the introduction of this marine species in the Siwa Oasis was related to fish farming activities carried out in the springhead by local inhabitants. We further hypothesize that the primary negative consequence of this invasion is likely to be the alteration of diatom community composition, with possible replacement of characteristic native taxa. Biological invasions place further pressure on spring habitats in oases, where they are affected by numerous growing human impacts, including global climatic changes. Therefore, legislation to protect these springs and enable sustainable and adaptive management, coupled with raised public awareness, is urgently needed to safeguard and conserve these unique biodiversity hotspots.

Freshwater biodiversity is disproportionally endangered and under-prioritized. Algal Red Lists literature is very limited, and there are only two editions of a single diatom-specific Red List (developed for Germany), in spite of the importance of diatoms for biodiversity and global ecosystem functioning. We used and analysed the new diatom Red List, compared to the previous edition, to show that these diatom microalgae threat status data allow, on one hand, a characterization of the ecological integrity and of the diatom diversity of the different types of inland-water ecosystems (also of practical importance to designate the most relevant habitats for conservation purposes), including a clear assessment of the threat status of the habitat, and, on the other hand, they offer ample possibilities to track the effects of stressors and of environmental change. Our results revealed, among other things, that: (1) threatened taxa concentrate in dystrophic-oligotrophic environments; (2) ‘not threatened’, i.e. tolerant and opportunistic, taxa are most frequent in eutrophic and saline ecosystems; (3) most local diatom extinctions happened in carbonate oligotrophic habitats. In this study, nitrates could be shown to possess a highly significant negative association with the cumulative percentage of diatom taxa in threat categories of the Red List. Having included heterogeneous studies (diverse inland-waters, different geographic areas, from close-to-pristine to impacted, neo- and paleolimnology etc.), we think that this strong negative association is noteworthy and points to the high potential of diatom-Red-List based approaches, especially if these would be tailored for the different biogeographic and climatic ecoregions.

Saber A.A., El-Tablawy N.H., El-Refaey A.A., Saber H., Singh P., Janse van Vuuren S., Cantonati M. 2022. Cyanoprokaryotes and algae: Classification and habitats. Chapter 1 In: Handbook of Algal Biofuels, M. El-sheekh & A. Abomohra (Eds). Elsevier. 38 pp. DOI: 10.1016/B978-0-12-823764-9.00024-8

A faintly heteropolar Brachysira species, with an acutely rounded headpole and a base pole which is sometimes slightly protracted, found in two lakes in northern Italy and Corsica, is described and named Brachysira chiaruccii sp. nov. This proposed new species can be differentiated from similar species by recognizable characters or character combinations: valve outline and symmetry, shape of the apices and of the central area, striation density, size, anchor-shaped terminal raphe endings (SEM feature), ecology. Brachysira chiaruccii sp. nov. is so far known to colonize oligotrophic, circumneutral, sufficiently buffered, moderately low conductivity mountain lakes, whilst the typical habitat of the most similar (North American) heteropolar Brachysira species (B. ocalanensis) is dystrophic, very low alkalinity and pH environments. The description is based on SEM and LM micrographs which document the full spectrum of shape variability along the size diminution series (including girdle views), plastid arrangement and morphology, and ecological preferences, in particular along the pH-alkalinity gradient.

1. The epilithon of steep sandstone and shale rock-walls (Molasse) was investigated in a part of Lake Constance (Überlinger See; southern Germany) between 2017 and 2019 and compared to the findings of Lauterborn and Zimmermann from 100 years ago. 2. The main objective was to find evidence to support the hypothesis that the brown alga Bodanella lauterbornii might have been displaced from its type habitat by invasive mussels due to competition for space (hard substrata). 3. Striking changes in phytobenthos species composition had occurred. Only scant remains of the rich and extensive algal vegetation were found. The once pronounced depth zonation with its characteristic indicator species no longer exists. Likewise, the worldwide-rare Bodanella lauterbornii, formerly a major component of the epilithon, was not found. 4. The most reasonable explanation for the strong decline in benthic colonisation by algae is that the zebra mussel had invaded the sandstone and shale rock-walls from the late 1960s onwards. Presently, this species forms extensive colonies on the walls up to a depth of 30 m, lately together with the new invader, the quagga mussel. KEYWORDS fresh water, globally-rare brown macroalga, endangered species, invasive species, large peri-Alpine lakes, Bodanella lauterbornii, dreissenids, Molasse

More or less needle-shaped species of Fragilaria s.s. are difficult to identify. Here we contribute to the taxonomy of this difficult group by describing three species new to science from very low conductivity mountain freshwater environments. Two of the new species resemble taxa established by Kützing in the early 19th century: F. rumpens and F. vaucheriae. Fragilaria spinaspeciosa sp. nov., from a seepage (helocrenic spring) in the northern Apennines, is superficially similar to F. rumpens, but has a lower stria density. Fragilaria tridentina sp. nov. is distinguished from F. gracilis by its smaller length-to-breadth ratio and more closely spaced areolae. Fragilaria vaucheriaeraetica sp. nov. is distinguished from F. vaucheriae and F. microvaucheriae by its outline and denser striae. These last three species also have distinctly different ecologies. Fragilaria vaucheriaeraetica sp. nov. is found in very low conductivity, very low nitrate, ultra-oligotrophic waters, while F. vauche...

Abstract We studied morphology and phylogeny of a Chara vulgaris (Charophytes, Charales) population sampled from the thermal “Springs of Moses” (Ayun Musa, Sinai, Egypt). Morphology of freshly sampled and cultivated materials was compared in order to quantify the influence of culturing conditions on morphological features. Cultivated material was shorter and had a smaller internode diameter than the freshly collected material. The bracteoles in the freshly collected material were distinctly longer (about 4–12 times the length of an oogonium) than those in the cultured material (about 2–4 times). Moreover, oogonia were slightly longer in the cultured material. Genetic analysis of the matK gene clearly identified the sampled specimens as Chara vulgaris. However, the freshly collected material was found to differ from “typical” Chara vulgaris populations in one morphological and one life-cycle feature. The thalli were fairly delicate, and the antheridia were shed early in both freshly collected and cultured materials, while oogonia were still in place. Most of the plants prepared and observed in this study were found to bear plenty of oogonia, whilst antheridia were often missing. Antheridia were only present on the newly formed branchlets at the stem apex. The peculiar morphology and life-cycle characteristics of this C. vulgaris population may be adaptations to this highly isolated and selective desert freshwater habitat.

Abstract Two Rhizoclonium strains thriving in contrasting spring types (slightly hot spring/ambient, shaded pool spring) and biogeographic areas (El-Farafra Oasis in the Western Desert of Egypt/River-Po Plain in Northern Italy) were studied in depth based on field and cultured material, bright-field and fluorescence microscopy, and phylogenetic molecular analyses (SSU and LSU rRNA gene sequences). This polyphasic approach revealed that the two Rh. strains clearly belonged to the Rhizoclonium clade but differed in some of their key diagnostic features. The Egyptian Rhizoclonium strain, isolated from the spring-fed (Ain El-Balad) agricultural ditch in El-Farafra Oasis, was described with the working name ‘Rhizoclonium sp. 10.6 μm from a desert, slightly-hot spring’ based on its smaller cell diameter, ecological and phylogenetic molecular traits compared to allied morphospecies. Moreover, it was highlighted that the L/D ratio can be more than 3.0 within this group. The Italian Rhizoclonium strain, collected from the Fontanile Valle Re-shaded, pool ambient spring (Emilia-Romagna Region), was virtually identical to other strains identified as Rh. hieroglyphicum from China and Japan, due to its highly supported congruence in morphological characteristics and phylogenetic position. This study provided the first partial LSU and SSU rRNA gene sequences for European Rh. hieroglyphicum based on available literature. Phenotypic plasticity of rhizoid formation was also observed in both Rhizoclonium strains studied using culturing approaching techniques. Our investigation also confirms that a lot of work with a variety of approaches is still needed to assess the ecological preferences, morphological plasticity, and phylogenetics of freshwater Rhizoclonium taxa worldwide.

The stalked diatom Didymosphenia is being thoroughly studied because it can cause serious nuisance blooms. The species most commonly involved is D. geminata. Although Didymosphenia species occur in running waters and lakes, published reports generally refer to lotic habitats. Given the applied interest in Didymosphenia, as well as its suitability for fundamental ecological studies, here we report an observation of a Didymosphenia bloom occurring on the southern part of the eastern shore of the large oligotrophic Lake Hövsgöl (Mongolia). LM and SEM observations revealed that the bloom was formed by Didymosphenia laticollis. The bloom extended for a long stretch of the eastern shore whilst on the opposing lake margin no bloom was visible, where a different Didymosphenia species was collected (D. mongolica). We interpreted the Lake Hövsgöl D. laticollis bloom in light of the most updated knowledge on Didymosphenia blooms ecophysiology. Lake Hövsgöl meets all main environmental requirem...

This opinion paper introduces a special series of articles dedicated to freshwater benthic algae and their use in assessment and monitoring. This special series was inspired by talks presented at the 9th International Congress on the Use of Algae for Monitoring Rivers and Comparable Habitats (Trento, Italy, 2015), the latest of a series of meetings started in 1991. In this paper, we will first provide a brief overview of phytobenthos methods in Europe. Then, we will turn towards the 'dark side' of phytobenthos and describe four particular problems for phytobenthos assessment in the European Union: (1) over-reliance on a single group of algae (mostly diatoms) to the exclusion of other groups; (2) relatively low adoption of benthic algae for ecological assessments in lakes; (3) absence of measures of phytobenthos abundance; (4) approaches used to define boundaries between ecological classes. Following this, we evaluate the strengths and limitations of current phytobenthos asse...

The type materials of Odontidium hyemale, Odontidium anomalum var. longissimum (longissima), Diatoma hiemale var. maxima (maximum), Odontidium anomalum, and additional materials from the Faroe Islands, Austria, Switzerland, Italy and Macedonia were studied in LM and SEM. The nomenclature of these taxa is explained and original drawings presented. In addition, two new species, Odontidium rostratum and Odontidium apiculatum are described from Macedonia and Italy. The history and taxonomic changes of Odontidium are presented and its separation from Diatoma at the genus level explained in more detail.

Here, we describe and discuss a method based on microscopical field of view (FOV) area to estimate diatom absolute abundances (densities or concentrations), and we statistically verify its reliability, also comparing it to another commonly used method (microspheres). To test the new method, we purposely performed replicate counts, both with the FOV and with the microsphere method, on both subfossil and recent material (samples) from mires. Intraclass correlation (ICC) revealed a high degree of agreement between the measurements obtained for the replicates with each of the two methods, suggesting that both are reliable for measuring diatom valve concentrations. However, the FOV consistently overestimated diatom absolute abundances, as compared to the microsphere method, and the ICC value used to assess the reliability of the two methods combined suggested that the two methods cannot be used interchangeably. The FOV method is relatively simple, has a lower cost, wider applicability, h...

Spring ecosystems are diverse transition zones between ground- and surface-water habitats. Due to their characteristics and vulnerable species assemblages, springs are considered indicator systems for monitoring environmental change. In particular, climate change is expected to alter spring-ecosystem features, such as water temperature and discharge, affecting otherwise typically stable biotic and abiotic conditions. However, reliable trend-development recognition and analysis require a uniform methodology and comparable data series over long periods of time. Spring research findings in the Berchtesgaden National Park and the Adamello-Brenta Nature Park have been consolidated to develop methodological recommendations to create lasting societal-added value. The successful transfer of the methodology to the Bavarian Forest National Park and the experienced contribution of the Bavarian Association for the Protection of Nature (Bavarian Climate Alliance) strongly improved method validat...

In the Egyptian deserts, new land reclamation projects have been recently established to meet the increasing-population growth rate and food demand. These projects mainly depend on the different groundwater aquifers. El-Farafra Oasis is one of the “1.5-million-feddan reclamation project” areas recently established in the Western Desert of Egypt where the only available water source is the world’s largest fossil freshwater reservoir “the Nubian Sandstone Aquifer System (NSAS)”. Groundwater-dependent springs, and their artificial counterpart “drilled wells”, are reliable water systems throughout the world. In the present study, hydrochemical parameters were collected in 2015 from 16 different springs and wells of the El-Farafra Oasis, and analyzed using the different water quality indices. The calculated water quality index (WQI), its correlations with the water quality parameters Gibbs, Piper, US Salinity-Lab Staff and Wilcox diagrams, and Principal Component Analysis (PCA) were used...

Present-day information available on the charophyte macroalgae in Egypt, including their phylogenetic affinities, remains largely incomplete. In this study, nine charophyte populations were collected from different aquatic biotopes across the Egyptian Western-Desert Oases and Sinai Peninsula. All populations were investigated using an integrative polyphasic approach including phylogenetic analyses inferred from the chloroplast-encoded gene (rbcL) and the internal transcribed spacer (ITS1) regions, in parallel with morphotaxonomic assignment, ultrastructure of the oospore walls, and autecology. The specimens identified belonged to the genera Chara, Nitella, and Tolypella, with predominance of the first genus to which five species were assigned though they presented some interesting aberrant taxonomic features: C. aspera, C. contraria, C. globata, C. tomentosa, and C. vulgaris. Based on our integrative study, the globally rare species C. globata was reported for the second time for th...

Environmental conditions, such as nutrient concentrations, salinity, elevation etc., shape diatom assemblages of periphytic biofilms. These assemblages respond rapidly to environmental changes, a fact which makes diatoms valuable bioindicators. Hence, freshwater biomonitoring programmes currently use diatom indices (e.g. EU Water Framework Directive - WFD). To date, microscopy-based assessments require high taxonomic expertise for diatom identification at the species level. High-throughput technologies now provide cost-effective identification approaches that are promising, complementary or alternative tools for bioassessment. The suitability of the metabarcoding method is evaluated for the first time in the Cyprus streams WFD monitoring network, an eastern Mediterranean country with many endemic species and results are compared to the results acquired from the morphotaxonomic analysis. Morphotaxonomic identification was conducted microscopically, using the most updated taxonomic co...

Peatland is a major carbon (C) sink, sequestering more atmospheric carbon dioxide (CO 2 ) than any other terrestrial ecosystem. Peatlands, and especially bogs, are typically nutrient-poor environments, extremely sensitive to increases in nitrogen (N) deposition. In fact, increasing N content often causes a shift from a mossto a vascular-plant-dominated vegetation resulting in lower C sequestration rates and/or mobilization of N and C stored in peat by promoting microbial activity. Peatlands are also very selective environments (sub-oxic to anoxic conditions, acidic pH, low N), and thus important habitats for nature conservation because of the occurrence of specifically adapted organisms. Peatlands cover ca. 3% of the world’s land surface but Europe lost >60% of this habitat type in the last decades. Moreover, in Italy they are in a marginal position from the phytogeographical standpoint.

The paper reports the first detailed study of the diversity of euglenoids recorded from the El Farafra Oasis in the Western Desert of Egypt. Four of the 20 identified species are new records for the Egyptian algal flora: the colorless Peranema inflexum Skuja, and the three pigmented species Euglena adhaerens Matv., Phacus crassus Zakryś & M. Łukomska and Ph. cristatus Zakryś & M. Łukomska. A brief description and original documentation are given for each reported morphospecies.

In this overview (introductory article to a special issue including 14 papers), we consider all main types of natural and artificial inland freshwater habitas (fwh). For each type, we identify the main biodiversity patterns and ecological features, human impacts on the system and environmental issues, and discuss ways to use this information to improve stewardship. Examples of selected key biodiversity/ecological features (habitat type): narrow endemics, sensitive (groundwater and GDEs); crenobionts, LIHRes (springs); unidirectional flow, nutrient spiraling (streams); naturally turbid, floodplains, large-bodied species (large rivers); depth-variation in benthic communities (lakes); endemism and diversity (ancient lakes); threatened, sensitive species (oxbow lakes, SWE); diverse, reduced littoral (reservoirs); cold-adapted species (Boreal and Arctic fwh); endemism, depauperate (Antarctic fwh); flood pulse, intermittent wetlands, biggest river basins (tropical fwh); variable hydrologi...

A small standing-water ecosystem (SWE) is a shallow (<20 m) lentic water body with a surface of a few hectares (≤10 ha). Compared to larger counterparts, they exhibit wider ecotones, sometimes even equaling their whole surface, which maximizes structural heterogeneity, supporting exceptionally high biodiversity, metabolic rates, and functionality. Surprisingly, no binding regulations support global strategies for SWE conservation. This work consists of a literature review performed for the period 2004–2018 to assess the ecological and conservation value of SWEs and the contribution of the Water Framework Directive (WFD) in promoting their conservation. Outcomes from this work open new perspectives on SWEs, which emerge as valuable ecosystems, and confirm their pivotal contribution to watershed biodiversity, resilience, and functionality. Results also suggest clear narrative trends and large knowledge gaps across geographical areas, biological components, and target issues. Additi...

Background and aims – The samples on which this study is based were collected in two streams in Puerto Rico as part of a long-term monitoring program conducted by the National Ecological Observatory Network (NEON). Detailed study of the diatom assemblages revealed the occurrence of a new diatom species belonging to the genus Adlafia. Methods – The study considered 82 samples of epilithic diatoms from two streams in Puerto Rico (Rio Cupeyes and Rio Guilarte) subjected to different degrees of anthropogenic impacts. The new species description is based on high-quality Nomarski (DIC) LM micrographs which document the full spectrum of shape variability along the size diminution series (including girdle views), and SEM images documenting valve ultrastructure (including detailed internal views). In addition we provide information about ecological preferences with respect to trophic state / nutrients, habitat within the stream channel / microhabitat (riffle, run, pool), and season of maximu...

Background and aims – The detailed analysis of algae and cyanoprokaryotes in a heterogeneous group of spring habitats (including all the different typologies) of the northern Apennines (Emilia-Romagna Region, Italy) revealed a new Amphora species in a small mountain flowing spring with low conductivity, and a new Halamphora species in a large, inland-saline (Triassic gypsum), fast flowing spring (Poiano spring). The present study aims to describe in detail these two new species found in contrasting spring types. Methods – This study is based on light microscopy (both fresh –for plastids – and prepared materials) and scanning electron microscopy observations, as well as a thorough morphological, physical, chemical, and biological characterization of the habitats. Key results – Amphora eileencoxiae sp. nov. is most similar to A. vetula (and allied taxa), and is characterized by the outline with acutely rounded, moderately ventrally bent ends, by the dimensions, and by the well-defined...

The main objective of this paper is to report new information about the distribution and ecology of a recently described diatom species, Geissleria gereckei. The opportunity for updating the information on the distribution and ecology of the species was provided by the finding of well-developed G. gereckei populations on the lithic material and bryophytes in the Raška and Mlava rivers (Serbia). For several years after the first description, G. gereckei has been known only from the type locality and from another spring in the Dolomiti Bellunesi National Park (the south-eastern Alps). After accurate LM and SEM observations, we provide evidence for the occurrence of the species also in the two above-mentioned rivers in Serbia, as well as in the south-western and south-eastern Alps. After an extensive literature search, it appears that the species is known with certainty only from these sites. Our observations and details from the literature suggest that the species is able to occupy a ...

Saber A.A., El-Tablawy N.H., El-Refaey A.A., Saber H., Singh P., Janse van Vuuren S., Cantonati M. 2022. Cyanoprokaryotes and algae: Classification and habitats. Chapter 1 In: Handbook of Algal Biofuels, M. El-sheekh & A. Abomohra (Eds). Elsevier. 38 pp. DOI: 10.1016/B978-0-12-823764-9.00024-8

The zooplankton community of an ox-bow pond in Northern Italy was investigated twice-weekly from November 1988 to March 1990. Principal component analysis (PCA), cluster analysis, and the trend of Shannon's diversity point out two important factors which determine the structure of the zooplankton community: 1) the temperature (i.e. seasonal cycle), strongly correlated with the first axis in PCA (35%); 2) the short term evolution of the pond, in which expansion of the macrophyte Myriophyllum spicatum has progressively reduced the portion of free water. It is suggested that selective predation by fish plays an important role in determining the species composition of the community as regards size-structure.

Cantonati M., Stevens L., Pringle C.M., Turak E. & Poikane S. (Guest Eds.). (2017-)2020. Multiplicity, characteristics, main impacts, and stewardship of natural and artificial freshwater environments: Consequences for biodiversity conservation. Water 9-12. Virtual Special Issue. 14 papers.
https://www.mdpi.com/journal/water/special_issues/freshwater_biodiversity_conservation

The rationale of this Virtual Special Issue (VSI) was to collect papers that discuss the potential of the different natural and artificial freshwater habitat types to contribute to freshwater biodiversity conservation. We were especially seeking articles illustrating the potential of near-natural and man-made freshwater habitats (focus could be narrowed on ecological categories, e.g., phytobenthos- or taxocoenoses, etc.) for biodiversity conservation by examining their ecological characteristics, conservation status, and main impacts affecting them. We thus aimed at addressing the multiplicity of still and running freshwater environments (Cantonati et al. 2020; introductory paper), from headwaters down to large rivers and lakes (papers published in the VSI are cited in the following): groundwater and dependent ecosystems, springs and spring-fed streams (Taxböck et al. 2017, Zelnik et al. 2018, Lai et al. 2019, Rossini et al. 2020, Stevens et al. 2020, Taxböck et al. 2020), headwaters (Richardson 2019), glacial streams (Füreder & Niedrist 2020), streams, large rivers, ancient and large lakes, high-mountain lakes, oxbow lakes, reservoirs, urban freshwater habitats (Turak et al. 2020), mires (Marazzi et al. 2019), small wetland ecosystems (Bolpagni et al. 2019), Boreal and Arctic freshwater habitats (fwh), Antarctic fwh, Mediterranean fwh, tropical fwh (Seeteram et al. 2019), arid-climate fwh.
Keywords: Near-natural freshwater habitats, man-made freshwater habitats, freshwater biodiversity, conservation ecology, biodiversity inventorying, environmental-quality assessments, water-level fluctuations (WLF).

Cantonati M. (Ed.), 1998 - Le sorgenti del Parco Adamello-Brenta (In Italian with English and German summaries). Parco Documenti, 11. Publisher and distributor: Parco Adamello-Brenta, Via Nazionale 12, I-38080 Strembo (Trento). 177 pp.

Marco Cantonati (ed.) - The springs of the Adamello-Brenta Regional Park. Hydrobiological researches on mainly pristine springs.

Key words: springs, Adamello-Brenta Regional Park, physico-chemistry, acidification, algae, diatoms, cyanophytes, mosses, higher plants, macrozoobenthos, water mites, microcrustaceans, copepodes, ostracodes, Hydrobioidea.

Schlagwörter: Quellen, Adamello-Brenta Naturschutzgebiet, physikalisch-chemische Eigenschaften, Versauerung, Algen, Kieselalgen, Blaualgen, Moose, höhere Pflanzen, Makrozoobenthos, Wassermilben, Mikrocrustaceen, Copepoden, Ostracoden, Hydrobioidea.

Summary
From 1992 to 1996, 30 mainly pristine springs of the Adamello-Brenta Regional Park (Trentino, Italy) were studied with the objective to produce a first inventory of the broadest possible spectrum of organisms and to identify sites for a long term monitoring programme.
The springs, distributed over a large altitudinal range (from 1073 to 2172 m a.s.l.), showed mean seasonal discharges which ranged from a few millilitres to 80 l s-1 and a wide range of substrate particle sizes (from silt to boulders and bedrock). Most of the springs are rheocrenes, i.e. flowing springs. However, the biotopes studied also include two helocrenes (seepage springs), two hygropetric rheocrenes (small rheocrenes springing from the rock), a rheohelocrene (a seepage spring on a slope) and a limnocrene (a pool spring). Physico-chemical differences among some of the morphological types of sources were recognised: helocrenes tend to differ from rheocrenes because of more marked oxygen undersaturation (30-80%), higher carbon dioxide content (15.0-31.0 mg l-1) and lower pH values (5.8-6.4). Half of the springs are situated in the Brenta mountain group (limestones and dolomites) and have waters with medium mineralization levels (152-300 µS25°C cm-1) and half in the Adamello massif (crystalline rocks) with very soft waters (11-64 µS25°C cm-1). Five of the latter springs have a reduced buffering capacity with bicarbonate contents between 2 and 6 mg l-1 and are consequently menaced by acid depositions (rain and snow). Rainfall may also play a major role in determining nitrate concentrations (74-1010 µg l-1 NO3--N, mean 486 µg l-1 NO3--N) which are in general not as low as expected for pristine environments. However the total phosphorus values (mean 6.6 µg l-1) classify all sites as oligotrophic. Temperature and conductivity decrease linearly with altitude: the first because of the lowering of the mean temperatures of the air and the second because of the reduced dimensions of the aquifers. The springs exhibit stability of the chemical and physical properties in the 24-hour time interval, whereas seasonal variations are sometimes more pronounced. The discharge is frequently characterised by notable changes, with peaks in autumn (rainfall) and spring (thaw) and minima in summer and winter. The variation of the temperature values during one year exceeds 2 °C in twelve of thirty cases. On the contrary, conductivity, pH and redox potential show almost always little seasonal variations.
The phytobenthos of the springs consists of algae, aquatic lichens and mosses. As regards algae, the main groups are diatoms and cyanophytes. In rheocrenes with swift currents also the chrysophyte Hydrurus foetidus is important and in the helocrenes cyanophytes are replaced by green algae as the dominant algal group. Up to 250 diatom taxa were identified and 48% of these should be classified as endangered (to various degrees) according to the German red list. Several poorly known taxa were found and even a species (“Cymbella -Cymbopleura-cantonatii“) and two varieties new for science were described from the material collected. Also the blue-green algae, 40 taxa of which were found, included several (25% according to Austrian lists) rare species and a new taxon (Pulvinularia sp.) the correct taxonomic position of which is being studied. The algal flora showed important similarities with that of springs and even headwater streams from other geographic areas. The quantity of cyanophyte species in the single springs is moderately low, while diatom species numbers were similar to those found in mountain streams. However differences among springs are marked leading to high total numbers of species. The mineral content of the waters was observed to be an important factor in determining the distribution of algae in these mainly pristine waters. The monthly sampling of epilithic diatoms in two springs showed that seasonal changes of the community structure are low, the highest species numbers being reached at the beginning of the summer. Thanks to their marked sensitivity to several environmental factors diatoms allowed to detect springs sensitive to acidification, to slight nutrient enrichment, to seasonally drying and to copper contamination respectively.
Unlike other groups of organisms, mosses and higher plants are not limited to the wet perimeter of the spring. The distribution of the spring vegetation shows a mosaic pattern which in many cases is arranged along a moisture gradient which depends from the degree of influence of the spring water on the surrounding area. The high number of species found in the nineteen springs of the River Sarca (245 higher plants and 58 mosses) is caused by the penetration of plants of neighbouring vegetation units into the spring vegetation. The phytosociological classification of the communities of the springs on carbonate substrate led to the identification of four associations, which are differentiated by an altitudinal gradient and are characterised by the genus Cratoneuron. The montane association Cratoneuretum commutati is substituted by the Cratoneuron decipiens-association in the subalpine- and by the Cratoneuretum falcati in the alpine- vegetation zone. The Cratoneuretum filicini was found in the slightly warmer springs of the Ceda valley. The plant associations of the springs on siliceous substrate display different structures at each station, because of the higher variability of local environmental conditions. In springs with higher discharge there are associations of aquatic mosses (Scapanietum undulatae, Fontinalis antipyretica - assemblage and Schistidio-Hygrohypnetum), while the communities of the other springs were not clearly identifiable using the phytosociological literature. However, in the Adamello group the fraction of springs in which endangered species were found is clearly higher (8 from 9) as in the Brenta (2 from 9).
For the 19 springs in the River Sarca catchment a first screening of the macroinvertebrate assemblages was performed. 96 taxa were identified, the dominant groups being midges, stoneflies and caddisflies. In the helocrenes these were replaced by limnophilous taxa (cockles, roundworms). Several taxa with poorly known distribution were collected, in particular Rhyacophila sp. gr. laevis which was only very rarely recorded from Italy. Diversity in the individual springs was low. The typical character of these macroinvertebrate assemblages was the large differences from spring to spring which allowed to suppose that only discharge and substrate particle size are generally relevant regulating factors.
Nineteen water mite species were found in the 30 springs sampled. One of the most significant results is the very high (80%) fraction of strictly spring dwelling species. From a faunistic point of view the most noteworthy finding is Partnunia angusta (second sure indication for Italy). In a spring influenced by slight copper contamination and in seasonally dry springs no water mites could be collected.
Twenty-one species of microcrustaceans (12 copepodes and 9 ostracodes) were found. The dominant species were typical crenophiles. From a faunistic point of view, the presence of some species considered rare in Italian waters was confirmed, but above all the finding of a cyclopoid species of the genus Diacyclops new for science deserves attention.
Just one species (Graziana alpestris) of crenobiontic snails of the superfamily Hydrobioidea was found in two springs in the Brenta group, very likely because of the difficulty of these organisms in recolonizing this recently (even in historical times for the higher elevations) deglaciated area.
In conclusion, we think that the results of this case study may furnish sound arguments for the protection of spring biotopes. However, at the present time, in Italy the awareness of the naturalistic importance of springs is still low. Therefore the spread of knowledge about these arguments, in which Natural Parks may play a key role, becomes extremely important.

Cantonati M. 2005. Algae. In: F. Stoch (Ed.), Pools, ponds and marshes. Quaderni habitat 11: 28-37. English Edition: Italian Habitats. Ministero dell’Ambiente e della Tutela del Territorio. Museo Friulano di Storia Naturale. ISBN 88 88192 22 0

Last year (2007) in Berlin the 21. Deutschsprachiger Diatomologen  Treffen became at the same time the 1st Central European Diatom Meeting. This change was underlined by an evident increase
in the number of participants. This trend continued with the second edition of the congress: The 2nd Central European Diatom Meeting in Trento. This was somewhat unexpected since this year (2008)
also the International Diatom Symposium will take place in a few months (07-13/09/2008) in Dubrovnik, Croatia, and several delegates announced that they would not be able to attend both meetings. In spite of this, as can be seen in Fig. 1, about hundred delegates registered for the Congress. It is therefore with satisfaction that we have the possibility to observe that their nationalities are very diverse, with an important contribution from non-German speaking countries
(Italy – “location effect” -, Czech Republic, Russia). We feel very honoured in acknowledging that some participants made long journeys to join our Congress, coming e.g. from Scotland, the eastern part of Russia, Israel, and Canada! Not surprisingly most of the participants work in Universities, but a significant share carries out its diatom investigations in other research institutions (e.g. Research Councils), and in Museums and Botanical Gardens (Fig. 2). This last observation is of special interest for us, since this year the Congress is organized in a Museum. In such Institutions, fundamental research (in particular
biodiversity documentation), collections, and educational issues and popularization are topics of prominent importance.
The topics covered by the contributions of the participants are diverse, but could be grouped into the categories shown in Fig. 3. These give an idea of ongoing diatom research in Central Europe. Not surprisingly biodiversity remains an important topic. Less obvious and – in our opinion encouraging – is the attention still given to taxonomy, a discipline which has difficulties in being acknowledged as a fundamental tool of ecological and applied research by administrators and decision makers.
In thanking the participants for coming to Trento and contributing to the Congress, we are happy that the Trentino Nature & Science Museum of Trento, a town that is not German speaking but that has always been a gate for those coming from Italy and approaching the German-speaking
area, can contribute to the continuation of the Central European Diatom Meetings, formerly Deutschsprachige Diatomologen Treffen.

Cattle grazing and trampling is a cause of peatland degradation resulting in peat compaction, shift in plant and microbial community composition, and N inputs in form of excreta. In Alpine peatlands overgrazing has been identified as a main problem for habitat integrity and biodiversity.
In the present work, 50-cm deep Belarus cores were collected from the Canton di Ritorto peatland (Adamello-Brenta Nature Park, Trentino, Italy) along a grazing-induced disturbance gradient.
Preliminary data show that small-scale grazing significantly lowered water content (by 5-10%) and gravimetric water content (by 30-50%), and increased bulk density (1.5-2.2x) compared to the control. Moreover, N concentration was 2-to-3 times higher in grazing-affected sites. Differences between cores affected by grazing and the control were evident in the top 20 cm. More than 80 diatom species were
identified throughout the two cores. Several of these are included in threat categories of the Red List for central Europe, and we could also identify a putative species new to science. Some species that tolerate moderate nutrient enrichment were found in the core at the "grazed" extreme of the gradient, whilst several species sensitive to organic pollution were detected only (or were clearly more frequent) in the control.

Marchetto A. & Cantonati M. 2017. Nascita e sviluppi della limnologia alpina. Atti Meeting L’acqua nelle terre alte: un percorso di ricerca attraverso il sistema alpino: 11-13. Verbania Pallanza - CNR ISE, December 4th 2015. CNR Edizioni. ISBN 978 88 8080 263 1
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Brief history of the origins and developments of high-mountain limnology in Italy and Europe.

Die Diatomeen im Gebiet der Stadt Treuchtlingen. Erwin Reichardt. 2018. 2 volumes with linen cover. 1184 pp. with more than 10,600 figures on 451 plates. Selbstverlag der Bayerischen Botanischen Gesellschaft, Munich, Germany. €330.00 [hardback: ISBN 978-3-00- 060715-8].
Die Diatomeen im Gebiet der Stadt Treuchtlingen represents the work of a lifetime of Erwin Reichardt, world-renowned, selfmade, amateur diatomist, and one of the leading specialists on Gomphonema Ehrenberg. In English the title would read The diatoms in the area of the city of Treuchtlingen. The incredibly high number of diatoms that can be found in an area of only c. 100 km2 is documented in depth. It comprises two large volumes including 1184 pages and, most importantly, over 10,000 photographs arranged in more than 450 plates (Fig. 1). The first volume starts with an extensive abstract in both German and English. A two-page introduction explains the goals, with emphasis on the detailed documentation of the diatom microflora of a relatively small but geologically heterogeneous region.A chapter on the study area provides insight into the diatom richness of the study region. The methods chapter not only lists routine techniques and approaches but also provides valuable suggestions, e.g. on diatom photography. Descriptions of the study sites, sometimes including temperature, conductivity, and pH data, follow in the subsequent chapter. Chapter 5 is the core of the work, and provides comments on the taxa found (but without classical descriptions) and their distribution. The rest of the book comprises photographic plates (LM& SEM; plates 1–149 in the first volume, and plates 150–451 in the second volume).

Die Diatomeen im Gebiet der Stadt Treuchtlingen, by Erwin Reichardt, München, Selbstverlag der Bayerischen Botanischen Gesellschaft, 2018, 2 volumes with linen cover, 1184 pp., with more than 10,600 figures on 451plates, euro 330.00 (hardback), ISBN 978-3-00-060715-8 _____________________________________________________________________ The first volume starts with an extensive abstract in German and English. A two page introduction explains the goals and aspirations of the work, with emphasis on the detailed documentation of the diatom flora of a relatively small, but geologically heterogeneous, region, and the desire to leave a heritage of descriptions, micrographs, and samples that will allow sound scientific comparisons in the decades/centuries to come. There was also an ambition to speak to the non-technical audience, in particular to politicians and managers, to foster an awareness of the necessity to deal responsibly, rationally, and respectfully with the nature of our homeland, and to protect nature as a whole (not only nature reserves) from destruction. A chapter on the study area provides insights (e.g. geological heterogeneity) into the, somewhat unexpected, richness of the diatom flora of the study region. The methods chapter should not be skipped, as it not only lists routine techniques and approaches but also provides valuable hints, e.g. on diatom photography (paragraph 3.3.3). The following chapter provides descriptions of the study sites (River Altmühl, larger streams, small streams and ditches, springs, ponds and tarns, small freshwater bodies, aerial sampling sites), including some physical and chemical variables whenever possible. Chapter 5 is the core of the text, and provides comments on the taxa found (including identification problems, and taxonomic status, if necessary) and their distribution. As many as 730 diatom taxa were found, and ‘only’ 23 species are described as new to science. The rest of the book comprises the invaluable photographic plates (LM and SEM), with plates 1–149 in the first volume, and plates 150–451 in the second volume.

This is the draft of a report (in German) that, after a period of availability online for possible comments by Colleagues, will be adopted as a standard for the long-term monitoring of springs to unveil the effects of climate and environmental change.

Chiare, fresche e dolci acque. Vita nelle sorgenti / Clear, crisp and fresh waters. Life in spring habitats My contribution (video powerpoint in Italian) on springs as habitats / environments / ecosystems and related problems of nature conservation has been published on YouTube for the MUSE online dissemination project "SLIDING SCIENCE - NATURE LESSONS". The target audience is primarily scholastic (first two years of high schools). The format to follow was Pecha Kucha: 20 slides with a voice commentary of no more than 20 seconds. It penalizes complex topics a bit... https://www.youtube.com/watch?v=PhxzDZRTaIg&t=293s