https://www.jlimnol.it/index.php/jlimnol/issue/feed Journal of Limnology 2020-01-22T17:32:27+00:00 Nadia Moscato nadia.moscato@pagepress.org Open Journal Systems <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> <h3 style="color: #194480;">The Special Issue <strong><a href="/index.php/jlimnol/issue/view/66">Recent advances in the study of Chironomidae: An overview</a></strong> is now available</h3> https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2019.1907 TEP production under oxidative stress of the picocyanobacterium Synechococcus 2020-01-22T17:32:26+00:00 Cristiana Callieri cristiana.callieri@irsa.cnr.it María B. Sathicq mbelen@ilpla.edu.ar Pedro J. Cabello-Yeves pcabello@umh.es Ester M. Eckert estermaria.eckert@cnr.it Justo Salvador Hernández-Avilés isalvaha@unam.mx <p>Transparent exopolymer particles (TEP) are mainly acidic polysaccharides directly or indirectly formed by phytoplankton and bacteria. These particles are often colonized by picoplankton and considered a hot spot for microbial activity. Recent studies suggested an important role of <em>Synechococcus</em> in TEP production found in lakes and prompted us to further investigate this issue using monoclonal xenic cultures of <em>Synechococcus</em>. We tested TEP production under oxidative stress in two treatments, one with hydrogen peroxide and another treated with ultraviolet radiation (UVR) and high photosynthetic active radiation (PAR), compared with an unstressed control. Our results showed a cell-normalized TEP production, ranging from 12 to 238 ng C cell<sup>-1</sup> among strains, not only under stress but also in the control with non-limiting nutrients. Our data prove that freshwater communities of <em>Synechococcus</em> and their associated heterotrophic microflora, are capable of producing TEP even during growth phase. The oxidative stress induced extra production of TEP up to 400 ng C cell<sup>-1</sup> in one of our phycocyanin-type (PC) strain. The phycoerythrin-type (PE) strains increased TEP production, particularly under UV-PAR stress, whereas the PC strains did it under H<sub>2</sub>O<sub>2</sub> stress. This study provides new perspectives on the potential role of freshwater <em>Synechococcus</em> in TEP production.</p> 2019-07-10T00:00:00+00:00 ##submission.copyrightStatement## https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2019.1903 The importance of environmental differences in the structuring of rotifer functional diversity 2020-01-22T17:32:27+00:00 Anita Galir Balkić agalir@biologija.unios.hr <p>A dynamic change in environmental conditions among floodplain habitats with different geomorphology might be a significant trigger in determining rotifer functional diversity. The aim of the study was to test the importance of environmental differences between several waterbody types, their positions within the floodplain and supporting microcrustacean communities in the structuring of rotifer functional feeding guilds. The study was conducted in Kopački rit floodplain during 2008 at five sites (two lakes, two channels and the main river). ANOSIM showed a significant difference in spatial distribution among rotifer feeding guilds. Redundancy analyses indicated biotic variables to significantly influence rotifer functional diversity in lake systems while in channel environments and the main riverbed guild representation was mainly influenced by limnological variables. Individual guild abundance changed relative to the site position within the floodplain as well, where the increased distance from the main riverbed resulted in increased rotifer numbers, and a different proportion of microfilter-feeders and macrofilter-feeders was recorded. The multiple linear regression showed a significant relation of macrofilter-feeder rotifers with microcrustaceans pointing to notable exploitative competition among these groups. The results highlight the ecological importance of all types of natural floodplain habitats necessary for preserving and maintaining the rotifer diversity.</p> 2019-06-26T00:00:00+00:00 ##submission.copyrightStatement## https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2019.1902 Climate projection of Lake Superior under a future warming scenario 2020-01-22T17:32:26+00:00 Katsumi Matsumoto katsumi@umn.edu Kathy S. Tokos katsumi@umn.edu Joseph Rippke katsumi@umn.edu <p>In a future warming world, a fully dynamical model of Lake Superior projects that the lake will undergo significant physical and biological changes by the middle of the 21<sup>st</sup> century with important implications for the surrounding region. Projections for the winter include drastically reduced ice and very weak water column stratification. In contrast, the summertime surface warming is projected to begin earlier, last longer, and be more enhanced. In concert, summertime biological production is projected to shift earlier and become larger. These changes have potentially important consequences for stakeholders with interests in shipping, coastal habitability, fishing, water quality, and recreation. Perhaps more fundamentally, the projected changes imply that Lake Superior may change into a different kind of lake with a dramatically weakened dimictic behavior.</p> 2019-07-08T00:00:00+00:00 ##submission.copyrightStatement## https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2019.1848 Life history of Karualona muelleri (Richard, 1897) (Chydoridae, Aloninae) 2020-01-22T17:32:25+00:00 Eliana A. Panarelli panarelli1969@gmail.com Helen A. O. Kawamura hakawamura@gmail.com Lourdes M. A. Elmoor-Loureiro elmoor.loureiro@gmail.com Francisco D. R. Sousa fdiogo.rs@gmail.com Paulo H. C. Corgosinho pcorgo@gmail.com Daniel Previattelli dpreviattelli@gmail.com Carlos E. F. Rocha cefrocha@ib.usp.br <p>Many taxonomic issues still need to be solved for the family Chydoridae, but mainly in the subfamily Aloninae. The species <em>Karualona muelleri</em> is an example of a recent taxonomic redefinition, since it was decoupled from the genus <em>Alona</em> and translocated to another genus. In order to expand our knowledge on the species, we investigated population growth and compared the morphometry of the first and second instars, male, parthenogenetic female, ephippial female, and ephippium. An experimental population was obtained by hatching resting eggs collected from the sediment in a temporary lake located in the Serra da Canastra National Park (Minas Gerais, Brazil). The hatched individuals were subjected to morphometric analyses and used in experiments to assess population growth and fecundity. Reproductive age and lifespan were also monitored in two groups of females in different life stages: parthenogenetic and gamogenetic. The reproductive age occurred between the 1<sup>st</sup> and 15<sup>th</sup> days of life, and the greatest longevity was 17 days. The start of gamogenetic reproduction was stimulated by elevated population densities and it characterized the slowdown of exponential population growth. Morphometric analyses detected differences between the development phases, as well as similarities in the morphological features of the male, first and second instars, and the two types of females.</p> 2019-07-26T00:00:00+00:00 ##submission.copyrightStatement## https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2019.1916 Distribution of subfossil chironomids (Diptera, Chironomidae) along a water depth gradient in the shallow Lake Spore, northern Poland 2020-01-22T17:32:24+00:00 Krzysztof Pleskot krzysztofpleskot@gmail.com Mónika Tóth toth.monika@okologia.mta.hu Karina Apolinarska karinaap@amu.edu.pl <p>Subfossil chironomid (Diptera, Chironomidae) remains are often used as indicators of lake level changes in palaeolimnological studies. However, their usefulness as a water depth proxy can vary between the sites, depending on the lake morphology, mode of taphonomic processes or amplitude of past water level fluctuations, among other factors. In this study, we have examined the distribution of subfossil chironomids in the shallow Lake Spore (northern Poland) to assess the influence of water depth on the fauna. Our aim was to evaluate the site-specific utility of subfossil chironomids for lake level reconstruction at Lake Spore. The subfossil chironomid assemblages in Lake Spore have heterogeneous distribution, suggesting they are predominately composed of remains deposited close to the sampling location. A strong relationship between the water depth and the chironomids is marked by the 25.12% variance explained by water depth in the taxonomic data. Moreover, according to generalized linear models (GLMs) out of 44 dominant taxa, 12 have significant relationships with water depth. However, the sensitivity of our chironomid fauna to water depth changes is not continuous along the entire depth gradient. The most abrupt assemblage change occurs at 2.6–3.7 m water depth, in proximity to the depth where macrophytes become less dense and finally disappear. We conclude that, despite these strong chironomid-water depth relationships, only major water level fluctuations can be satisfactorily reconstructed due to the limited turnover rates of the fauna along a depth gradient and relatively small amplitude of the lake level variations characteristic for East-Central Europe.</p> 2019-08-05T00:00:00+00:00 ##submission.copyrightStatement## https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2019.1874 Trophic relationships between primary producers and associated fauna in a pristine Cerrado pond 2020-01-22T17:32:24+00:00 Elisa A. C. C. Alvim elisa.alvim@gmail.com Tiago B. Kisaka tiagobk.df@gmail.com Gabriela B. Nardoto gbnardoto@gmail.com Luciana de Mendonça-Galvão luciana.mendoncagalvao@gmail.com Barbara M. Fonseca barbara.fonseca0603@gmail.com Mercedes M.C. Bustamante mercedesmcb@gmail.com <p>Ponds arising from groundwater in Cerrado of Central Brazil are oligotrophic but highly biodiverse environments. In this study, we used stable isotope ratios to test if there are variations in carbon and nitrogen acquisition by different primary food sources and if they are influenced by seasonality in a well-preserved pond. We hypothesized that periphyton is the main food source for macrophyte-associated fauna. We found that δ<sup>13</sup>C, but not δ<sup>15</sup>N, can distinguish between primary food sources; however, the isotopic signatures of food sources did not differ significantly between seasons. The δ<sup>15</sup>N values of macrophyte-associated fauna were significantly higher for predators compared with other trophic groups, but δ<sup>13</sup>C values did not differ significantly between groups. Emergent macrophytes and periphyton were the main food sources for scrapers (contribution of 42.5%) and collector-gatherers (contribution of 41.6%), respectively. Compared with emergent macrophytes, submerged macrophytes were associated with a greater abundance of fauna and algal biomass but were not a significant food source for associated fauna. Our findings demonstrate that in this small shallow oligotrophic pond in the Cerrado, the stable isotope ratios of carbon and nitrogen of food sources did not vary between seasons but did differ between aquatic macrophyte life forms. We point out the different functional roles of macrophyte life forms, with emergent macrophytes serving as an important food resource, while submerged macrophytes mainly provide physical structure.</p> 2019-08-27T00:00:00+00:00 ##submission.copyrightStatement## https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2019.1877 Winter decrease of zooplankton abundance and biomass in subalpine oligotrophic Lake Atnsjøen (SE Norway) 2020-01-22T17:32:23+00:00 Thomas C. Jensen thomas.jensen@nina.no <p>Despite the rapidly changing winter conditions in temperate ecosystems, little attention has been devoted to the effects of these changes on lake ecology. Few studies on the seasonal changes in abundance and biomass of the major groups of the metazooplankton community (<em>i.e.</em> rotifers, cladocerans and copepods) in northern oligotrophic lakes include data from the ice-covered winter months. This study reports monthly variation in zooplankton abundance and biomass from June 2010 to October 2011, including winter, in an oligotrophic, subalpine lake in southeastern Norway (Lake Atnsjøen). Changes in rotifer, cladoceran, copepod, and total zooplankton abundances and biomass were related to seasonal variation in water temperature and phytoplankton biomass by means of ordination analysis. The zooplankton abundance and biomass were much lower in winter than during the open water season. However, an under-ice phytoplankton bloom occurred during the final winter months, when snow cover and ice thickness were reduced and (presumably) light penetration increased, leading to an increase in abundance of copepod nauplii. Winter zooplankton abundance was dominated by copepods and rotifers, while winter zooplankton biomass was dominated by copepods and cladocerans. Both phytoplankton and zooplankton had two biomass peaks in 2010 and one peak in 2011. Rotifers dominated zooplankton abundance with a peak in August and total zooplankton abundance followed a similar pattern. In contrast, cladocerans dominated zooplankton biomass with a peak in July and total zooplankton biomass also peaked at this time. Rotifer and total zooplankton abundance and rotifer biomass were most closely correlated to water temperature. However, cladoceran biomass and total biomass were most closely correlated with phytoplankton biomass, but also appeared to be dependent on other carbon sources. Estimates of non-phytoplankton particulate organic carbon indicated that this part of the carbon pool could be an additional food source for zooplankton particularly in early and mid-winter. The longer growing season in 2011 than in 2010, owing to earlier ice-off in 2011, may have contributed to higher phytoplankton and zooplankton biomass in 2011. With climate warming, this is an expected change in temperate lake ecosystems.</p> 2019-09-10T00:00:00+00:00 ##submission.copyrightStatement##