Journal of Limnology 2019-11-19T19:02:37+01:00 Nadia Moscato 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 both applied and theoretical. Proceedings of workshops, specialized symposia, conferences, may also be accepted for publication. The <strong>Journal of Limnology</strong> is published in three issues per year, open access online and each article is available for downloading for free. A printed version is also available at the annual subscription rate of € 160. For further information on subscription terms, rates, modes of payment and shipping, etc. please contact the Publisher at <a href=""></a></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> Environmental factors as drivers for macroinvertebrate and diatom diversity in Alpine lakes: New insights from the Stelvio National Park (Italy) 2019-11-19T19:02:37+01:00 Angela Boggero Silvia Zaupa Simona Musazzi Michela Rogora Elzbieta Dumnicka Andrea Lami <p>Information on the biodiversity of high altitude lakes in the Stelvio National Park was scarce and fragmentary, in most cases limited to a few studies on a single biological issue. To fill this gap, a multidisciplinary research program was established in 2011 to investigate macroinvertebrates, diatoms, and water chemistry in 8 high altitude lakes within the boundaries of the Park (Rhaetian Alps, Eastern Alps). The results of this study were compared with data on biological assemblages and chemical parameters of Alpine lakes in the Pennine-Lepontine Alps (Western Alps), to evaluate the role of local drivers with respect to regional ones. This comparison was possible thanks to the adoption of standardized sampling methodologies developed since the ’90s by the National Research Council-Water Research Institute (Verbania), in collaboration with several European Research centers. Despite located in a restricted geographical area, the lakes of the Stelvio National Park showed a high variability of chemical composition, and of sensitivity to acidification, lower than that of the Pennine-Lepontine Alpine lakes. Macroinvertebrate and diatom taxa were ubiquitous and frequent along the Alps, and mainly represented by cold-stenothermal species. Richness, Shannon, Simpson, and Pielou indices applied to phyto- and zoobenthos highlighted significantly lower values in Stelvio National Park lakes than in those of Pennine-Lepontine for macroinvertebrates, while no significant differences were found for diatoms. Two groups of lakes were identified by Cluster Analysis, mainly on the basis of major ion concentrations. Canonical Correspondence Analysis showed that the macroinvertebrate assemblage of the lakes studied is driven mainly by altitude and lake surface, and, to a lesser extent, by nutrient content. On the contrary, pH and acid-related variables played a secondary role for diatoms, while nutrients and, more in general, ionic content had significant effects on their species composition. Overall, the results of this first investigation showed that the high elevation of these lakes affects their macroinvertebrate assemblages, while their diatom communities are comparable throughout the Alps.</p> 2019-02-08T00:00:00+01:00 ##submission.copyrightStatement## Ice cover decay and heat balance in Lake Kilpisjärvi in Arctic tundra 2019-11-19T19:02:36+01:00 Matti Leppäranta Elisa Lindgren Lijuan Wen Georgiy Kirillin <p>To gain more understanding of lake ice melting process, field research was carried out in an arctic tundra lake, Kilpisjärvi (surface area 37.1 km<sup>2</sup>, maximum depth 57 m) in the melting periods of 2013 and 2014. The heat budget of the ice cover was dominated by the radiation balance; turbulent heat fluxes were large in 2013 due to warm air advection but small in 2014. Transmittance of solar radiation through ice was 0.25 in 2013 and 0.10 in 2014, snow-ice was absent in 2013 but in 2014 accounted for 50% of the ice cover. The melting rate was 4.4 cm&nbsp;&nbsp; &nbsp;d<sup>-1</sup> in 2013, 1.9 cm d<sup>-1</sup> in 2014. The portions of surface, bottom and internal melting were, respectively, 2.9, 1.0 and 0.5 cm d<sup>-1</sup> in 2013 and 0.8, 1.0 and 0.1 cm d<sup>-1</sup> in 2014. Internal melting was realized in increase of ice porosity. In 2013 a rapid ice breakage event completed the ice breakup in short time when ice porosity had reached 40-50%. A lake ice melting model should include the thickness and porosity of ice, with porosity connected to an ice strength criterion.</p> 2019-02-21T00:00:00+01:00 ##submission.copyrightStatement## Phytoplankton responses to an extreme drought season: A case study at two reservoirs from a semiarid region, Northeastern Brazil 2019-11-19T19:02:36+01:00 Carlos Y. B. Oliveira Cicero D. L. Oliveira Ayanne J. G. Almeida Alfredo O. Gálvez Danielli M. Dantas <p>The temporal phytoplankton biomass variation at two Neotropical reservoirs during an extreme drought season were analyzed. Here we sought to evaluate the main abiotic factors involved in dynamics of phytoplankton during this drought period. The main difference between the reservoirs was the intensive fish and shrimp farming in one of the reservoirs. For quantitative analysis, sampling with bottles were carried out at an average depth of 0.5m. Water temperature, pH and electrical conductivity parameters were measured <em>in situ</em> and water samples were collected for dissolved inorganic nitrogen and soluble reactive phosphorus analyses. Aquaculture was probably one among the causes for the reservoirs were so different in the physical and chemical variables, as shown by the principal components analysis. The results showed specific groups dominance in both reservoirs. In the Cachoeira II reservoir, an invasive dinoflagellate, <em>Ceratium furcoides</em>, was present in all analyzed months, while, in the Saco I reservoir, cyanobacteria group represented more than 50% of phytoplankton biomass, mainly <em>Microcystis aeruginosa</em> and <em>Dolichospermum</em> sp. In two reservoirs precipitation, soluble reactive phosphorus and electrical conductivity were positively related with phytoplankton. Phytoplankton biomass was considerably larger in the Cachoeira II reservoir, due to the greater size and biovolume of the dominant dinoflagellate. These findings suggest that species dominance in extreme drought events may be favored.</p> <p><strong><br> </strong></p> 2019-02-21T00:00:00+01:00 ##submission.copyrightStatement## Allodiaptomus nongensis, a new diaptomid copepod (Copepoda: Calanoida) from a tributary of the Mekong River, with notes on its consumption by local people in Central Laos 2019-11-19T19:02:35+01:00 La-orsri Sanoamuang Santi Watiroyram <p>A new calanoid copepod, <em>Allodiaptomus nongensis</em> n. sp., is herein described based on samples collected from the Xe Lanong River (a tributary of the Mekong River), and 13 other localities in Central Laos. This is the sixth species of the genus <em>Allodiaptomus</em> Kiefer, 1936. The other five members in the genus were recorded from India, South China, Cambodia, Thailand, and Vietnam. The features that stand out in the new species are in the male: the right caudal ramus has a large, biacuminate, conical process proximally, and the Exp-2 of the right P5 has a hook-shaped principal spine proximally. The new species is abundant in both temporary and permanent waters, but is restricted to Savannakhet Province. This Laotian endemic copepod is referred to by local people as “Pa Khayong”, which means tiny fish. Since high densities of this copepod can be found in the dry season (December until May), several man-made copepod traps are placed by local people along the river banks in Muang Nong District. Interestingly, large concentrations of individuals (body length: ~1 mm) belonging to the new species are harvested and consumed by these villagers. Additional information about this species and the copepod fisheries by local people in this area is provided herein. In this paper, the reassignment of <em>Allodiaptomus rarus</em> to the genus <em>Mongolodiaptomus</em> is proposed.</p> 2019-03-18T00:00:00+01:00 ##submission.copyrightStatement## Geochemistry of major and trace elements and their environmental significances in core sediments from Bosten Lake, arid northwestern China 2019-11-19T19:02:34+01:00 Wen Liu Jilili Abuduwaili Long Ma <p>Geochemical element concentrations of a 41-cm-long sediment core from Bosten Lake were analyzed with grain size, total organic carbon and total inorganic carbon, and environmental evolution over the past ~150 years was reconstructed. Based on principal component analysis (PCA) and correlation analysis of the elements, three controlling factors for vertical distribution characteristics of elements were identified, the first factor was the combined effects of terrigenous detritus and endogenous carbonate, the second controlling factor was the granularity effects of the lake sediment, the third controlling factor was the input from human activities. A first stage was from the 1870s to the 1950s, Bosten Lake was in a natural state, the deposition rates were relatively low, and the concentrations of Ca, Sr, and Ba were high. The second stage was from the 1960s to the 1990s, triggered by the inflow of agricultural return water, the sedimentation rates were clearly higher than the former stage, the concentrations of Al, Fe, and K increased notably, and Ca, Sr, and Ba decreased. The third stage comprised the period since the 2000s, the scope of human activities has been extended. Enrichment factors of Cd, Pb and P of the sediment have increased. The economic development in the basin led to an increase in pollution of the lake. Human impacts on the environmental change were embodied in the enrichment of Cd, Pb, and P, and the clear decline of biogenic Ca. Sediment geochemistry has faithfully recorded the impacts of human activities on the environmental changes of Bosten Lakes.</p> 2019-04-12T00:00:00+02:00 ##submission.copyrightStatement## Behavior of trap-and-transported Atlantic salmon spawners of hatchery origin in the Daugava River system (Latvia) 2019-11-19T19:02:34+01:00 Daniel Nyqvist Matiss Zagars Olle Calles Claudio Comoglio <p>Where migrating fish have to pass multiple dams, very high passage performance is required at the series of obstacles to avoid accumulated negative effects of multiple dam passage. In some rivers, migrating fish are trapped, transported past several obstacles, and released to continue their migration. Such trap-and-transport solutions, however, have seldom been evaluated. In the Daugava River, Latvia, several dams with no functional fishways block the river for migrating fish. A remnant Atlantic salmon population is being sustained by a sea ranching regime, where returning spawners are caught and artificially spawned, the juveniles raised in hatcheries, and smolts released in to the river in time for their seaward migration. Hatchery released fish, however, differ substantially from wild conspecifics, and in Latvia, as elsewhere throughout the range of salmon, reduced dependency on hatchery production and the re-establishment of wild salmon populations are being discussed. In the Daugava River system, suitable spawning and rearing habitat remains upstream two dams and an associated large reservoir in a mainstem tributary, the Ogre River, offering the potential to restore a wild salmon population. &nbsp;To explore the potential of a trap-and-transport solution to bring Atlantic salmon spawners in contact with remaining spawning grounds in the Daugava River system, spawners were caught, radio tagged, transported upstream of the two dams and the reservoir, and released to pursue their spawning migration in the tributary. Despite being unfamiliar with the river, some of the tagged spawners moved upstream, reaching areas up to 12 km from the release sites. Males were observed higher upstream in the river compared to females, and some males were tracked relatively close to potential salmon spawning habitat. Females, although displaying some movements in the lower parts of the river, were not observed close to any suitable spawning areas, highlighting potentially important sex differences in post trap-and-transport behaviour. Perhaps due to different responses to handling stress, such low post-transportation spawning success among females has the potential to negatively impact restoration efforts in the Daugava River system and elsewhere. The present study represents a first step towards the restoration of wild Daugava salmon, one of several unique Baltic Atlantic salmon populations, and a potential model for future restoration efforts. &nbsp;</p> 2019-04-05T00:00:00+02:00 ##submission.copyrightStatement## Predicting spatial distribution patterns and hotspots of fish assemblage in a coastal basin of the central-south of Chile, by geostatistical techniques 2019-11-19T19:02:33+01:00 Sam Catchpole Reinaldo Rivera Cristián E. Hernández Javiera De La Peña Pablo González <p>Currently the application of geographic information systems in the subjects of biology and ecology has facilitated the study patterns of distribution, richness y diversity of species. However, in freshwater ecosystems the application of geostatistical analysis are scarcely used in the worldwide, including Chile. Therefore, in our study we developed predictive maps using simple Kriging (resolution 12.5 x 12.5 m), based on richness and Shannon-Weaver diversity, and we analyzed spatial autocorrelation of fish assemblages (Moran and Getis-Ord index) present in the Andalién River basin. Our results established a fish assemblage composition of 24 species, most of them native (79%) and with endanger conservation status. Predictive maps showed highest values of richness and diversity of fish species in the potamon zone of the Andalién and Nonguén streams, while the low values were described in the Chaimavida sub-basin and the transition zone of Andalién River. The Moran and Getis-Ord index determined a cluster pattern of the data and define hotspot and coldspot zones, concordant with the predictive maps of richness and Shannon-Weaver diversity. The geostatistical and spatial techniques showed to be relevant tools for the determination of distribution patterns of freshwater species and conservation issues.</p> 2019-05-09T00:00:00+02:00 ##submission.copyrightStatement## Methane formation and consumption by sediments in a cross-channel profile of a small river impoundment 2019-11-19T19:02:33+01:00 Adam Bednařík Martin Blaser Martin Rulik <p>Rivers are a natural source of methane (CH<sub>4</sub>) into the atmosphere and may contribute significantly to total CH<sub>4</sub> emissions. Even though the details of sources of CH<sub>4</sub> in rivers are not fully understood, weirs have been recognized as a hotspot of CH<sub>4</sub> emissions. In this study, we investigated CH<sub>4</sub> production and consumption in air-exposed river sediments along a cross-channel transect located upstream of a weir. Stable carbon isotopes were used for determination of individual methanogenic pathways. In order to understand the relationship between physicochemical and biological processes, additional parameters such as organic matter, grain median size, and carbon and nitrogen content were characterized as well. Generally, samples from the surface sediment layer (0-10 cm) had higher CH<sub>4</sub> production than sediments from the deeper layer (10-20 cm) during the incubation experiments. Sediments near the bank zones and in the mid-channel were characterized by the highest organic carbon content (6.9 %) as well the highest methanogenic activity (2.5 mmol g<sup>-1</sup> DW d<sup>-1</sup>). The CH<sub>4</sub> production was predominated by H<sub>2</sub>/CO<sub>2</sub> dependent methanogenesis in the surface sediment layer (0-10 cm), while the proportion of acetoclastic and hydrogenotrophic methanogenesis in the deeper sediment layer (10-20 cm) was balanced. The CH<sub>4</sub> oxidation potential of sediments showed the same spatial pattern as observed for the CH<sub>4</sub> production. Our results showed high spatial variability of sediment CH<sub>4</sub> production and oxidation in the cross-channel profile upstream of the weir, whereas the highest CH<sub>4</sub> dynamics were observed in the littoral zones. This variability was closely linked with the carbon and nitrogen content in the sediment samples.</p> 2019-06-06T00:00:00+02:00 ##submission.copyrightStatement## Relationship between bream (Abramis brama) activity and water turbidity in a shallow lake under different season conditions 2019-11-19T19:02:32+01:00 Joan H. Hansen Jakob Brodersen Henrik Baktoft Christian Skov <p>The foraging activity of large-bodied benthivorous fish has been suggested to be of key importance for maintaining shallow lakes in a turbid state. Since especially the spring ecosystem dynamics determines the successive state of shallow lakes, such impact could depend on seasonality in benthivore activity patterns. However, we do not yet know to what extent the activity&nbsp;of&nbsp;large-bodied benthivorous fish affects lake turbidity across the year. In order to investigate seasonal dynamics in bream activity and its impact on water turbidity under natural conditions, bream daily activity was studied in a small (39 ha) shallow Danish lake using passive biotelemetry technology, i.e. a modified Passive Integrated Transponder (PIT)-tag antenna system. We tracked the activity of 448 benthivorous bream over a period of four years (2012 to 2016) and during the same period wind conditions, water turbidity and temperature was measured. Results showed a clear relationship between bream activity and water turbidity at water temperature below 15°C indicating that winter season activity of benthivorous bream may play an important role for maintaining lake ecosystems in a turbid state. Also wind speed and wind direction affected water turbidity, suggesting that wind induced resuspension can be important even in small shallow lakes. This is to our knowledge the first full-scale study under natural conditions to describe how bream activity influence lake turbidity on a day-to-day basis. Our findings also add a seasonal component to previous findings by showing that benthivorous feeding bream have the potential to increase water turbidity also in the winter season and thereby, ultimately, impact ecosystem functioning within shallow lakes.</p> 2019-06-17T00:00:00+02:00 ##submission.copyrightStatement## A place in space - the horizontal vs vertical factors that influence zooplankton (Rotifera, Crustacea) communities in a mesotrophic lake 2019-11-19T19:02:31+01:00 Maciej Karpowicz Jolanta Ejsmont-Karabin Adam Więcko Andrzej Górniak Adam Cudowski <p>The factors that influence plankton distribution in lakes are currently widely debated. The primary objective of this study was to determine a combination of factors that influence the three-dimensional distribution patterns of both rotifer and crustacean communities in a pelagic ecosystem. We compared the abiotic (temperature, oxygen and nutrients) and biotic (phytoplankton) factors that affect the horizontal and vertical distribution of zooplankton in different habitat conditions in Lake Wigry. The results of our study indicate that the vertical gradient in a water profile is much more important for microcrustaceans than horizontal changes in environmental conditions, whereas Rotifera showed a strong spatial autocorrelation when connected with differences in trophic status. Generally, large zooplankton prefer cold, darker waters of the metalimnion-hypolimnion, while smaller zooplankton prefer the warm epilimnion. This niche segregation in water profiles promotes a large diversity of pelagic zooplankton. The vertical distribution of dominant <em>Daphnia cucullata</em> was strongly related to the phytoplankton distribution. Moreover, we found that the large-bodied <em>Daphnia cucullata</em> prefers the lower water layers, despite the presence of less optimal food resources, while smaller individuals clearly prefer the warm surface water with high quality resources.</p> 2019-06-19T00:00:00+02:00 ##submission.copyrightStatement##