https://jlimnol.it/index.php/jlimnol/issue/feed Journal of Limnology 2019-04-17T17:30:15+02:00 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 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="mailto:info@pagepress.org">info@pagepress.org</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> https://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2018.1806 Ecology and conservation of the Mediterranean trout in the central Apennines (Italy) 2019-04-17T17:30:15+02:00 Massimo Lorenzoni massimo.lorenzoni@unipg.it Antonella Carosi acarosi@libero.it Massimo Giovannotti mgiovannotti@tiscali.it Gianandrea La Porta gianandrea.laporta@unipg.it Andrea Splendiani andreasplendiani@hotmail.com Vincenzo Caputo Barucchi v.caputo@univpm.it <p>The Mediterranean brown trout (<em>Salmo trutta</em> complex) is one of the freshwater fish species complex at greater risk of extinction in the Mediterranean area. The introduction of alien invasive species and their interaction with the native fauna represent some of the major threats to the survival of this species. Currently, the genetic variability of the Mediterranean trout (<em>Salmo trutta </em>complex) is being compromised by the introgressive hybridization with the Atlantic trout (<em>Salmo trutta</em> Linnaeus, 1758). Therefore, it is necessary to gain further knowledge on genetic and demographic characteristics of Mediterranean trout populations, that, combined with environmental and angling data, will allow to undertake sound conservation strategies. The aims of the present study were to analyze: i) the demographic characteristics of the Mediterranean trout in seven central Apennine river basins where native populations are threatened by stocking with the domestic trout of north Atlantic origin; ii) the influence of both environmental parameters and different fishery management strategies on the status of native trout populations. The project focuses on 14 sites included in the Natura 2000 EU wide network of nature protection areas, established under the 1992 Habitat Directive. A total of 25 watercourses were investigated for a total of 32 sampling sites. A census of the fish fauna was carried out by electrofishing at each sampling location. Fish and environmental data were collected in spring and autumn 2014. The results obtained in the present research allowed us to detect the presence of three residual Mediterranean trout populations with a high degree of genetic integrity in the study area. The native trout populations were characterized by higher abundances and higher adult density values. Well-structured native populations with higher legal-size specimens density and poor body conditions in terms of relative weight were observed in the no-fishing areas, probably due to the presence of intraspecific competition phenomena. The environmental analysis confirmed the key role played by the geological characteristics of the central Apennines in shaping the introgression levels observed in the wild trout populations, while the recovery of the water quality appears decisive in the development of management strategies aimed at their conservation.</p> 2018-09-17T00:00:00+02:00 ##submission.copyrightStatement## https://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2018.1767 Seasonality of the N2O cycle of the Biobío River during the megadrought 2019-04-17T17:30:14+02:00 Marcela Cornejo-D'Ottone marcela.cornejo@pucv.cl Ricardo Figueroa rfiguero@udec.cl Oscar Parra oparra@udec.cl <p>The mechanisms involved in N<sub>2</sub>O production, consumption and air-sea interactions in fluvial systems are modulated and affected by several factors, including hydrological, chemical and anthropogenic impacts. In recent decades, the basin of the Biobío River (central Chile) has been impacted by an enhanced precipitation deficit and anthropogenic pressure, so the aim of the present work is to understand the spatial and seasonal dynamics of N<sub>2</sub>O during a megadrought that has been affecting the river since 2010. We also aim to determine the annual contribution of N<sub>2</sub>O to the atmosphere and the possible response of the Biobío River to projected climatic changes. Seasonal sampling of the water physical-chemical properties was carried out at 15 stations along 280 km of the river and its five tributaries; the stations were distributed between the pristine headwaters (700 m asl) and the outlet of the river at the Pacific Ocean. The longitudinal distribution of oxygen, nutrients, and nitrous oxide evidenced agricultural, urban and industrial impacts on the river water. Headwater areas presented the highest oxygen concentration and the lowest nutrient and N<sub>2</sub>O concentrations, all of which fluctuated with the variability in water discharge with the different seasons. In the middle river section, where agricultural, industrial and urban activities impacted the river, the nutrient and N<sub>2</sub>O concentrations increased up to 20 and 1.2 times, respectively, compared to those in the headwaters, and the outlet area showed the highest nutrient and N<sub>2</sub>O concentrations. Throughout the entire river, N<sub>2</sub>O oversaturation exhibited a pronounced seasonal cycle with maxima occurring during the dry season. Our results suggest that urban activities had the greatest impact on the Biobío River at its outlet. Furthermore, the inverse relationship between the N<sub>2</sub>O concentration and water discharge suggests that the predicted future decrease in water discharge may result in higher N<sub>2</sub>O values in the Biobío River that would expectedly enhance global warming further, through a positive feedback.</p> <p>&nbsp;</p> 2018-09-27T00:00:00+02:00 ##submission.copyrightStatement## https://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2018.1763 Effect of climate change on thermal-ice regime of shallow lakes compared to deep lakes: Case study of lakes in the temperate zone (Northern Poland) 2019-04-17T17:30:07+02:00 Włodzimierz Marszelewski marszel@umk.pl Bożena Pius bpius@umk.pl <p>The objective of this study is to determine the usefulness of results of hydrological observations (1961-2015) carried out in a deep lake for the assessment changes in the ice-thermal regime of a shallow lake. The paper is based on results of daily values of surface water temperature and ice phenomena in shallow Lake Łebsko and deep Lake Charzykowskie. Similar, statistically significant, positive trends of water temperature were determined in both lakes (0.26°C 10 year<sup>-1</sup> in Lake Łebsko and 0.25°C 10 year<sup>-1</sup> in Lake Charzykowskie). The fastest increase in mean monthly water temperature in the analysed period (1961-2015) occurred in May (3.37°C in Lake Charzykowskie) and April (2.76°C in Lake Łebsko). The majority of elements of the thermal regime of surface waters in shallow lakes were generally determined to be similar to the same elements in deep lakes, and the effect of climatic changes on the thermal regime of both lakes was found to be similar. Less similarity is observed between elements of the ice regime, particularly in date of decline of the ice cover.</p> <p>&nbsp;</p> 2018-11-14T00:00:00+01:00 ##submission.copyrightStatement## https://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2018.1858 Nymphal feeding habits of two Anacroneuria species (Plecoptera, Perlidae) from Sierra Nevada de Santa Marta, Colombia 2019-04-17T17:30:05+02:00 Yesely Hurtado yeselyhurtado@gmail.com Cesar Enrique Tamaris-Turizo ctamaris@unimagdalena.edu.co Manuel Jesús López Rodriguez manujlr@ugr.es Jesús Manuel Tierno de Figueroa jmtdef@ugr.es <p>The knowledge of the diet of aquatic insects is important to assess the use of resources and overlap of trophic niche between species, as well as to understand their role in the food web of the freshwater ecosystems they inhabit. This is particularly necessary in tropical areas where information on this topic is scarce. The aim of the present work is to describe the feeding habits of the species <em>Anacroneuria marta</em> Zúñiga &amp; Stark, 2002 and <em>Anacroneuria caraca</em> Stark, 1995 in the middle section of the Gaira River (Sierra Nevada de Santa Marta, Colombia). We performed three samplings during the rainy and dry seasons in the two main different microhabitats of the reach (leaf packs and gravel) in 2014. The diet of a total of 87 and 90 individuals of <em>A. caraca </em>and <em>A. marta</em>, respectively, was studied. With this information, niche breadth for each species and niche overlap between them in terms of trophic resources were calculated. The main trophic resource for both species in the dry and rainy season was the animal matter. In the dry season, FPOM was also important in the diet of <em>A. caraca</em>, and<em> A. marta </em>ingested a great quantity of CPOM in the rainy season. Larvae of Trichoptera, were the most ingested prey in both species, followed by Chironomidae, Coleoptera Hydrophilidae, and Ephemeroptera. No differences in diet between both species were detected, so this could favor the niche overlap in terms of trophic resources and could lead to competition between them. The possible ecological scenarios are discussed.</p> 2018-12-05T00:00:00+01:00 ##submission.copyrightStatement## https://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2019.1853 Littoral mayfly assemblages in South-East European man-made lakes 2019-04-17T17:30:04+02:00 Marina Vilenica marina.vilenica@gmail.com Natalija Vučković natalija.vuckovic@biol.pmf.hr Zlatko Mihaljević zlatko.mihaljevic@biol.pmf.hr <p>Man-made freshwater habitats have been widely used to successfully modify the environment for human benefit, including purposes of irrigation, flood control or electricity generation. Over the past decade, our knowledge about the mayfly fauna and its ecology in South-East Europe has been growing, yet the data related to lentic assemblages remain very scarce. In this study, littoral mayfly assemblages were investigated at artificial and heavily modified lentic habitats in the Dinaric Western Balkan (n=21) and Pannonian Lowland (n=15) ecoregions. Mayfly nymphs were sampled during the summer months of 2016 or 2017. At each sampling site, ten samples were collected using a benthos hand net. A total of 21 mayfly species were recorded, though species richness per site was rather low (i.e., between zero and seven species). <em>Cloeon dipterum</em> (Linnaeus, 1761) was the most frequent species recorded, while <em>Caenis horaria</em> Linnaeus, 1758 was the most abundant. This study showed that the Croatian mayfly fauna is still growing, with the first record of <em>Siphlonurus aestivalis</em> Eaton, 1903 for the country. The assemblage structure was mainly dominated by lower reaches and lentic (potamal and littoral) elements and detritivores (gatherers/collectors and active filter feeders). Orthophosphates and chemical oxygen demand had the highest influence on mayfly assemblages, reflecting a higher level of pollution at sites in the Pannonian Lowland ecoregion, and consequently markedly lower mayfly abundances. As mayflies are widely used as bioindicators of freshwater ecosystems, detailed information about their assemblages in heavily modified and artificial habitats could contribute to future conservation activities of freshwater habitats and their communities. Additionally, these results could be applied in creating a monitoring system for artificial lakes according to the requirements of the European Water Framework Directive.</p> 2019-01-02T00:00:00+01:00 ##submission.copyrightStatement## https://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2018.1837 Quantification of Chaoborus and small fish by mobile upward-looking echosounding 2019-04-17T17:30:06+02:00 Roman Baran r.baran@centrum.cz Michal Tušer micker@centrum.cz Helge Balk helge.balk@fys.uio.no Petr Blabolil Blabolil.Petr@seznam.cz Martin Čech carcharhinusleucas@yahoo.com Vladislav Draštík v.drastik@gmail.com Jaroslava Frouzova jarkafrouzova@gmail.com Tomáš Jůza Tomas.Juza@seznam.cz Jan Kubecka kubecka@hbu.cas.cz <p><em>Chaoborus</em> larvae inhabit frequently the water column of lakes, when they can be mistaken for small fish. Because larvae ascend up to the blind zone of downward-looking echo sounding at night, quantitative acoustic estimation of them is possible only with upward-looking approach. For this reason, the mobile hydroacoustic upward-looking system (120 and 38 kHz split-beam echosounder) in combination with a direct catch method (trawling) was tested to investigate the night community of invertebrates and juvenile fish in the surface layer of the Římov reservoir (Czech Republic). In the target strength range of invertebrates (smaller than -59 dB), the 38 kHz echosounder recorded only a small proportion of targets while the 120 kHz echosounder recorded distinct peaks corresponding to high densities of <em>Chaoborus </em>(target strength, TS range -70 to -60 dB, average TS -66 to -64 dB). At 120 kHz frequency, the TS distribution of smaller cohort of juvenile fish (&lt;25 mm in length) overlapped the TS-distribution of&nbsp;<em>Chaoborus</em>. The number of these smaller juvenile fish was so small compared with the number of <em>Chaoborus</em> that they did not seriously bias acoustic <em>Chaoborus</em> estimate. The correlation between the density of <em>Chaoborus </em>with small contamination of juvenile fish larvae from trawling and acoustic recording made with the 120 kHz echosounder was high (R<sup>2</sup>= 0.88), but the acoustic densities from trace counting appeared to underestimate&nbsp;<em>Chaoborus</em>&nbsp;abundance when the density was &gt; 1.5 ind.m<sup>-3</sup>.&nbsp;</p> 2018-12-03T00:00:00+01:00 ##submission.copyrightStatement## https://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2019.1824 Sentinel-2 for mapping the spatio-temporal development of submerged aquatic vegetation at Lake Starnberg (Germany) 2019-04-17T17:30:05+02:00 Christine Fritz christine.fritz@mytum.de Katja Kuhwald doernhoefer@geographie.uni-kiel.de Thomas Schneider tomi.schneider@tum.de Juergen Geist geist@wzw.tum.de Natascha Oppelt oppelt@geographie.uni-kiel.de <p>Submerged aquatic vegetation (SAV) plays an important role in freshwater lake ecosystems. Due to its sensitivity to environmental changes, several SAV species serve as bioindicators for the trophic state of freshwater lakes. Variations in water temperature, light availability and nutrient concentration affect SAV growth and species composition. To monitor the trophic state as required by the European Water Framework Directive (WFD), SAV needs to be monitored regularly. This study analyses the development of macrophyte patches at Lake Starnberg, Germany, by exploring four Sentinel-2A acquired within the main growing season in August and September 2015. Two different methods of littoral bottom coverage assessment are compared, i.e. a semi-empirical method using depth-invariant indices and a physically based, bio-optical method using WASI-2D (Water Colour Simulator). For a precise Sentinel-2 imaging by date and hour, satellite measurements were supported by lake bottom spectra delivered by <em>in situ</em> data based reflectance models. Both methods identified vegetated and non-vegetated patches in shallow water areas. Furthermore, tall- and meadow-growing SAV growth classes could be differentiated. Both methods revealed similar results when focusing on the identification of sediment and SAV patches (R² from 0.56 to 0.81), but not for a differentiation on SAV class growth level (R² &lt;0.42).</p> 2019-01-02T00:00:00+01:00 ##submission.copyrightStatement## https://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2019.1861 Trait-based evaluation of plant assemblages in traditional farm ponds in Korea: Ecological and management implications 2019-04-17T17:30:03+02:00 Sungsoo Yoon yssfran@snu.ac.kr GoWoon Kim agnesgwkim@gmail.com Ho Choi forestho1@naver.com Chaeho Byun chaeho.byun@mail.mcgill.ca Dowon Lee leedw@snu.ac.kr <p>The Korean traditional farm pond called <em>dumbeong</em> is an important rural landscape element that supports local biodiversity and is useful in irrigating agricultural fields during dry periods. This study assesses how plant communities in <em>dumbeongs </em>respond to adjacent land use, water depth, open-water surface, and nutrient levels and irrigation usage. Plant functional and species groups, based on trait and species data respectively from 20 <em>dumbeongs </em>in Seocheon-gun, South Korea, were classified by hierarchical analysis and non-metric multidimensional scaling. Relationships between the plant community composition and explanatory variables at both the species and functional group levels were tested through redundancy analysis. The results showed that irrigation usage prevented nutrient accumulation and water depth reduction of the ponds, and we found water depth was the only significant factor that determined plant composition at both species and functional group levels. The plant functional groups were more useful than plant species in predicting plant composition in <em>dumbeong</em>s, owing to their collective response to water depth and open-water surface. Our results demonstrate that management practices of <em>dumbeong</em>, such as periodic drainage, sediment removal and control of dominant plant species, alter its plant communities and thus need to be considered for biodiversity conservation in agricultural landscapes.</p> <p class="a" style="line-height: 200%;">&nbsp;</p> 2019-01-03T00:00:00+01:00 ##submission.copyrightStatement##