Journal of Limnology <p>The <strong>Journal of Limnology</strong> publishes peer-reviewed original papers, review papers and notes about all aspects of limnology. The scope of the Journal of Limnology comprises the ecology, biology, microbiology, physics, and chemistry of freshwaters, including the impact of human activities, management and conservation. Coverage includes molecular-, organism-, community-, and ecosystem-level studies on both applied and theoretical issues. Proceedings of workshops, specialized symposia, conferences, may also be accepted for publication.</p> PAGEPress Scientific Publications, Pavia, Italy en-US Journal of Limnology 1129-5767 <p><strong>PAGEPress</strong> has chosen to apply the&nbsp;<a href="" target="_blank" rel="noopener"><strong>Creative Commons Attribution NonCommercial 4.0 International License</strong></a>&nbsp;(CC BY-NC 4.0) to all manuscripts to be published.<br><br> An Open Access Publication is one that meets the following two conditions:</p> <ol> <li class="show">the author(s) and copyright holder(s) grant(s) to all users a free, irrevocable, worldwide, perpetual right of access to, and a license to copy, use, distribute, transmit and display the work publicly and to make and distribute derivative works, in any digital medium for any responsible purpose, subject to proper attribution of authorship, as well as the right to make small numbers of printed copies for their personal use.</li> <li class="show">a complete version of the work and all supplemental materials, including a copy of the permission as stated above, in a suitable standard electronic format is deposited immediately upon initial publication in at least one online repository that is supported by an academic institution, scholarly society, government agency, or other well-established organization that seeks to enable open access, unrestricted distribution, interoperability, and long-term archiving.</li> </ol> <p>Authors who publish with this journal agree to the following terms:</p> <ol> <li class="show">Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.</li> <li class="show">Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.</li> <li class="show">Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work.</li> </ol> Attenuation of ultraviolet radiation and photosynthetically active radiation in six Yunnan Plateau lakes of China based on seasonal field investigations <p>Solar radiation is a primary driver affecting several physical, chemical and biological processes in lake ecosystems. The attenuation of sunlight in water is directly controlled by optically active substances. Here, the seasonal and interlake heterogeneities of the diffuse attenuation coefficients (<em>K</em><sub>d</sub>(λ)) of ultraviolet radiation (UVR) and photosynthetically active radiation (PAR) were studied based on field investigations in six Yunnan Plateau lakes (<em>i.e</em>., Chenghai, Dianchi, Erhai, Fuxian, Lugu and Yangzong) of China, October 2014‒July 2016. The results revealed that <em>K</em><sub>d</sub>(λ) generally increased with decreasing wavelength and increasing trophic state and that <em>K</em><sub>d</sub>(UVR) presented higher interlake heterogeneity than<em> K</em><sub>d</sub>(PAR). The interlake heterogeneity surpassed the seasonal heterogeneity of <em>K</em><sub>d</sub>(λ), whereas the intralake seasonal heterogeneity, which is related to the lake trophic state and solar spectrum, was obvious. Although the main factors affecting <em>K</em><sub>d</sub>(λ) were chromophoric dissolved organic matter (CDOM) and phytoplankton in general, the interlake heterogeneity was found. In eutrophic, turbid shallow Lake Dianchi, CDOM primarily affected UV-B, whereas total suspended solids (TSS) and/or phytoplankton had important effects on <em>K</em><sub>d</sub>(UV-B), <em>K</em><sub>d</sub>(UV-A) and <em>K</em><sub>d</sub>(PAR). CDOM, TSS and phytoplankton influenced the <em>K</em><sub>d</sub>(UV-B), <em>K</em><sub>d</sub>(UV-A) and <em>K</em><sub>d</sub>(PAR) in the deep mesotrophic Lake Chenghai and Lake Erhai, but the main particulate factors were different between these two lakes. In the deep, oligotrophic clear Lake Fuxian and Lake Lugu, only the significant effect of CDOM on<em> K</em><sub>d</sub>(UVR) in Lake Fuxian was detected. Additionally, the factors affecting <em>K</em><sub>d</sub>(λ) in Lake Yangzong were atypical, possibly due to the artificial addition of massive amounts of ferric chloride.</p> Weilu Wang Xuan Yang Licheng Huang Jiang Qin Qichao Zhou Copyright (c) 2020 The Author(s) 2020-02-26 2020-02-26 79 2 10.4081/jlimnol.2020.1951 The Observatory on LAkes (OLA) database: Sixty years of environmental data accessible to the public <p>Lakes are essential ecosystems that provide a large number of ecosystem services whose quality is strongly impacted by human pressures. Optimal uses of lakes require adapted management practices which in turn rely on physico-chemical and biological monitoring. Long-term ecological monitoring provides large sets of environmental data. When such data are available, they have to be associated to metadata and to be stored properly to be accessible and useable by the scientific community. We present a data informatics system accessible to anyone who requests it. Maintained online since 2014 (<a href=""></a>), it is originated from the Observatory on LAkes (OLA). It contains long-term data from 4 peri-alpine lakes (Lakes Aiguebelette, Annecy, Bourget, Geneva/Léman) and 24 high-altitude lakes of the northern French Alps. We describe the generated long-term data series, the data type, the methodologies and quality control procedures, and the information system where data are made accessible. Data use is allowed under the condition of providing reference to the original source. We show here how such a platform clearly enhances data sharing and scientific collaboration. Various studies referring to these data are regularly published in peer-reviewed journals; providing <em>in fine</em> a better understanding of lakes’ ecosystems functioning under local and global pressures.</p> Frédéric Rimet Orlane Anneville Denis Barbet Cécile Chardon Laura Crépin Isabelle Domaizon Jean-Marcel Dorioz Laurent Espinat Victor Frossard Jean Guillard Chloé Goulon Valérie Hamelet Jean-Christophe Hustache Stéphan Jacquet Leslie Lainé Bernard Montuelle Pascal Perney Philippe Quetin Serena Rasconi Antoine Schellenberger Viet Tran-Khac Ghislaine Monet Copyright (c) 2020 The Author(s) 2020-02-27 2020-02-27 79 2 10.4081/jlimnol.2020.1944 Grazing affects periphytic algal biomass in the periphyton-macrophyte relationship independently of the substrate type and nutrient status <p>The macrophyte–algae relationship has primary importance in affecting the functioning of shallow lake ecosystems. However, how substratum type, grazing, and nutrient status affect the relationship, is still largely unknown. Here, we studied algal assemblages covering either the submerged macrophyte, <em>Ceratophyllum demersum</em>, or artificial plastic plants with similar morphological complexity to answer these questions. Nutrient status was assessed as eu- and hypertrophic conditions in two separate lakes. In contrast to previous studies, the algal community on artificial substrates resembled to those observed on <em>C. demersum</em>. Independently of nutrient status (lakes), algae colonised artificial substrates intensively, but the highest algal biomass was observed in the hypertrophic lake. The community of periphytic algae was represented by diatoms, chlorophytes, and cyanobacteria. In the eutrophic lake, rather diatoms were present with high relative abundance, whereas, in the hypertrophic lake, rather cyanobacteria prevailed. Grazing pressure was high in both lakes and in the case of both substrate types, affecting the biomass of periphytic algae significantly. Our results indicate that macroinvertebrate grazing plays a crucial role in affecting periphytic algal biomass, independently of nutrient status and substratum type in shallow lakes.</p> Monika Tarkowska-Kukuryk Wojciech Pęczuła Tomasz Mieczan Copyright (c) 2020 The Author(s) 2020-01-22 2020-01-22 79 2 10.4081/jlimnol.2020.1941 Supraseasonal drought in an Alpine river: effects on benthic primary production and diatom community <p>Over the last decades, the ongoing global climate change, combined with consequent increasing water demand for human needs, is causing recurrent droughts in previously perennial streams. These phenomena have been dramatically increasing their extent, with significant repercussions on the entire food web. Consequences of water scarcity are particularly remarkable in mountain streams, where the frequency of droughts is increasing at a rate that does not allow species to adapt. In the present research, we monitored benthic diatom communities within an intermittent Alpine river (Pellice River; North-Western Italy) during the three key phases of its hydrological cycle: i) stable flow ii) lentification iii) rewetting of the riverbed after a supraseasonal drought lasting five months. We tested the response of diatom communities in terms of compositional, structural and functional metrics (primary production, species composition, ecological guilds, life forms and eco-morphological groups) hypothesising both taxonomic and functional changes during the different steps of this hydrological cycle. Significant changes in benthic chlorophyll <em>a</em> occurred in the three hydrological phases. In particular, the relative proportion of the chlorophyll <em>a</em> of the three main autotrophic groups inhabiting the periphyton (namely diatoms, cyanobacteria and green algae) resulted as a reliable metric for the evaluation of the hydrological disturbance. Diatom chlorophyll <em>a</em> significantly decreased during both lentification and drought. The three phases were significantly characterized by different species and functional groups. During the stable flow the <em>low profile</em> (i.e., species of short stature, adapted to high current velocities and low nutrients concentrations) was the most representative guild and <em>Achnanthidium pyrenaicum</em> was the most abundant species; this phase was also characterized by the presence of stalked taxa. We observed a significant decrease of <em>high profile</em> species (i.e., species of tall stature, adapted to high nutrients concentrations and low current velocities) during the lentification phase, which was characterized by taxa belonging to the genera <em>Navicula</em>, <em>Nizschia </em>and <em>Ulnaria</em>. During the rewetting, small and medium sized <em>high profile</em> diatoms as well as <em>motile</em> ones (i.e., fast moving species) characterized the assemblages. Our results showed that the complete recovery of diatom communities took at least 70 days after water return. The rapid and widespread extension of droughts in the Alpine area will have severe consequences on the river biota, also favouring the spread of invasive taxa. For this reason, outlining patterns of diatom response to droughts and detecting reliable metrics for the evaluation of this specific impact is very urgent and important.</p> Elisa Falasco Alberto Doretto Stefano Fenoglio Elena Piano Francesca Bona Copyright (c) 2020 The Author(s) 2020-01-15 2020-01-15 79 2 10.4081/jlimnol.2020.1933 Representative monitoring of the calcifying alga <em>Phacotus lenticularis</em> (Chlamydophyceae) in lentic ecosystems <p>The biogenic carbonate precipitation by the freshwater alga <em>Phacotus lenticularis</em> may play a role in long-term carbon (C) fixation that has not yet been quantified. This is partly due to the absence of a standardised methodology to representatively sample and assess the cell density and sedimentation of <em>P</em>.<em>&nbsp;lenticularis</em> in lakes. The objective of the present study was to define an adequate sampling methodology taking into account the spatiotemporal variation of <em>P</em>.<em>&nbsp;lenticularis</em> as well as the sedimentation and dissolution of calcite shells. Simultaneous measurements in three different lake sub-basins of Lake Grosser Ostersee, Germany, showed that the spatial cell density of <em>P.&nbsp;lenticularis</em> was similar in each sub-basin. At all sites, the vertical <em>P</em>.<em>&nbsp;lenticularis</em> cell density maxima corresponded with the slowly downshifting thermocline from depths of 2 to 6 m. During the entire growth period, composite samples from 0&nbsp;to&nbsp;7&nbsp;m included 89% of the total <em>P</em>.<em>&nbsp;lenticularis</em> population. Lake bathymetry, as well as external factors like wind exposure, did not appear to affect the abundance of these calcifying algae. Sediment traps at a depth below the thermocline (at 7&nbsp;m) and 1&nbsp;m above the lake bottom recorded sedimentation rates of <em>P</em>.<em>&nbsp;lenticularis</em> shell halves (sh) between 1.1×10<sup>6</sup> and 1.1×10<sup>8</sup>&nbsp;sh&nbsp;m<sup>−2</sup> d<sup>−1</sup>, while mean cell concentrations in the water column were between 1.1×10<sup>8</sup> and 1.7×10<sup>9</sup> shells per m². Sinking velocity ranged between 3 and 4 m d<sup>−1</sup>. Sediment from traps installed at a depth of 7 m did not reflect mean shell concentrations in the water column above. Dissolution of carbonates reduced the number of shells in sediment traps at the lake bottom and during the storage of samples. A laboratory experiment showed that even distilled water used for dilution during microscopic analysis led to dissolution of <em>P</em>.<em>&nbsp;lenticularis</em> shells. In conclusion, combined sampling of <em>P</em>.<em>&nbsp;lenticularis</em> from open water and sediment traps close to the lake bottom delivers a most representative assessment of biogenic carbonate precipitation. Due to dissolution effects, high temporal resolution along with appropriate sample preservation are crucial, whereas spatial representativeness was already achieved with low number of sampling sites per lake.</p> Sebastian Lenz Uta Raeder Juergen Geist Copyright (c) 2020 The Author(s) 2020-01-30 2020-01-30 79 2 10.4081/jlimnol.2020.1946 Erratum - Presence and identification of <i>Legionella</i> and <i>Aeromonas</i> spp. in the Great Masurian Lakes system in the context of eutrophication <p>This corrects the article entitled “Presence and identification of <em>Legionella</em> and <em>Aeromonas</em> spp. in the Great Masurian Lakes system in the context of eutrophication" by the authors Karolina Grabowska, Aleksandra Bukowska, Tomasz Kaliński, Bartosz Kiersztyn, Waldemar Siuda, and Ryszard J. Chróst, published with DOI <a href="" target="_blank" rel="noopener">10.4081/jlimnol.2019.1924.</a> In the Figures 3 and 4 the correct values for the number of studied bacteria are presented.</p> Karolina Grabowska Aleksandra Bukowska Tomasz Kaliński Bartosz Kiersztyn Waldemar Siuda Ryszard J. Chróst Copyright (c) 2020 The Author(s) 2020-06-01 2020-06-01 79 2 10.4081/jlimnol.2020.1969