The Journal of Limnology 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.
PAGEPress Scientific Publications, Pavia, Italy
Aquatic Diptera and their relationship with environmental variables in the lower part of the semi-arid Quilca-Chili River basin, Arequipa, Peru
Aquatic Diptera are a diverse and widely distributed group of insects globally. In Perú, knowledge about this group is limited, with existing studies focusing mainly on aquatic community ecology, water quality, and heavy metal pollution. This study aimed to analyze the composition and structure of aquatic Diptera and their relationship with environmental variables in the lower Quilca-Chili River Basin in southern Perú. Environmental variables were measured and Diptera samples were collected from 16 stations during June and October 2022. Community structure and its relationship with environmental parameters were analyzed under conditions of high and low river flow. The results revealed 13 families and 29 genera, with Chironomidae, Simuliidae, Empididae, Ceratopogonidae, Dolichopodidae, and Muscidae being the most abundant. The analysis of similarity and the non-metric multidimensional showed clear separation in dipteran composition and structure among rivers in June, while in October, only Quilca River differed significantly. The greatest variation in taxon richness between low and high flow seasons was observed in the Vitor and Quilca rivers. Diversity indices were compared across rivers and seasons using Kruskal-Wallis and Mann-Whitney tests (p<0.05). Significant differences occurred in evenness (June) and all indices (October). Among the physicochemical parameters, temperature and pH remained relatively stable across all rivers, while conductivity and total dissolved solids were consistently high. The canonical correspondence analysis indicated that in June, the abundance of Polypedilum and Forcipomyia was associated with organic matter. The genera Tabanus, Holorusia, Podonomus, Paltostoma, and Simulium were associated with dissolved oxygen. In October, Polypedilum abundance was positively related to turbidity, dissolved oxygen, salinity, and electrical conductivity, while Podonomus, Paltostoma, Tabanus, Bezzia, and Simulium were associated with river flow. These findings demonstrate that environmental variables significantly influence river conditions and determine the distribution of Diptera. This study contributes valuable insights into the aquatic Diptera communities of semi-arid river systems.
Department of Life Sciences and Systems Biology
Copyright (c) 2025 The Author(s) https://creativecommons.org/licenses/by-nc/4.0
Copepoda of lowland springs: diversity patterns and integrative taxonomy of Cyclops
Groundwater copepods in lowland Europe remain insufficiently studied compared to those from mountainous regions. Here, we present the results of a faunistic and ecological survey of lowland springs, conducted in the context of earlier research on groundwater copepods from over 100 wells in the same region. Springs, as natural interfaces between aquifers and surface waters, provide more diverse habitats and favorable conditions for groundwater-affiliated fauna. We examined copepod assemblages in 36 lowland springs in northeastern Poland, representing rheocrene, limnocrene, and helocrene types, which were sampled in summer and autumn. We identified a total of 23 species of Copepoda, comprising 13 Cyclopoida and 10 Harpacticoida. Most of these species were associated with hyporheic or groundwater habitats. Cyclopoida dominated in terms of abundance, especially in limnocrene springs, and showed little seasonal variation, while Harpacticoida exhibited markedly higher diversity and abundance in summer. The Cyclopoida assemblage was dominated by Eucyclops serrulatus, Diacyclops bicuspidatus, and Cyclops strenuus, whereas Harpacticoida were represented mainly by Attheyella crassa, Canthocamptus staphylinus, and by five Bryocamptus species. Many of the common copepod species were also found in groundwater wells in the same region. Still, overall richness, particularly of Harpacticoida, was higher in springs due to the presence of heterogeneous benthic microhabitats. We identified three Cyclops species in the springs that were not recorded in the groundwater (wells) of this region. Conversely, we did not detect C. furcifer in the studied springs, despite its presence in nearby wells and temporary puddles. To present taxonomic relationships within the genus Cyclops, we applied an integrative taxonomic approach that combined morphological traits with 12S rRNA and ITS-1 markers. This confirmed the presence of three distinct species: C. strenuus, C. insignis, and C. borealis (considered a senior synonym of C. heberti), for which we provide descriptions of key morphological traits together with molecular data. These findings highlight the function of lowland springs as ecotonal habitats fostering distinct copepod assemblages, including taxa characteristic of both groundwater and benthic microhabitats.
Digitalization of the tardigrade collection of Giuseppe Ramazzotti
The Collection of Tardigrada by Giuseppe Ramazzotti, preserved at the Water Research Institute of the National Research Council (CNR-IRSA) in Verbania, Italy, is composed of numerous slides and microscopic preparations of tardigrades, including animals and their eggs. It is a historical collection that includes samples taken over a period of years from 1938 to 1964 in Europe, Africa, North and South America by one of the Italian taxonomists working on the phylum Tardigrada. The dataset of the Ramazzotti Collection is composed of 3319 records, prepared within the Project ITINERIS (ITalian INtegrated Environmental Research Infrastructures System) dedicated to build the Italian Hub of Research Infrastructures in the environmental scientific domain. The purpose of creating this dataset is to protect the information through the digitalization of the samples, and to facilitate sharing the information on the animals collected by Ramazzotti and stored at CNR-IRSA, Verbania Pallanza. For this reason, each record in the database is associated with a photograph of the microscopic slide and with a photograph of the animal. The data is organized into a standardized Darwin Core Archive format, thus available globally, through the Global Biodiversity Information Facility infrastructure (GBIF). The Collection is also registered in the Global Registry of Scientific Collections (GRSciColl).
Copyright (c) 2025 The Author(s) http://creativecommons.org/licenses/by-nc/4.0
Response of freshwater periphytic diatoms to elevated cadmium concentration: results of an experimental study
The study highlights the importance of biological monitoring as an effective tool for assessing the impact of chemical substances on living organisms. It offers significant advantages in detecting ecological changes and contributes to a deeper understanding of environmental risks. The application of biological observation supports the protection of both public health and natural ecosystems. Aim of the study was to determinate impact of cadmium on periphytic diatoms biodiversity, structure under laboratory conditions and evaluate application of diatoms as cadmium bioindicators. Species diversity was found to decrease with increasing cadmium concentration in the water: 85 taxa of diatoms were identified in the control sample, and decreased with changing cadmium concentration, from 59 species at 0.01 mg Cd/l to 52 at 0.1 mg Cd/l. The concentration of cadmium in environment was reliably indicated by Navicula lanceolata, N. gregaria and N. rostellata, whose cell proportion significantly decreases with increasing cadmium, and Achnanthidium spp., and Fragilaria spp., whose proportion in the samples increases with increasing cadmium level. The frequency of frustule and theca carpel deformations increases at higher cadmium concentrations: at 0.01 mg Cd/l more than 8% of diatom cells become deformed, and at 0.04 mg Cd/l – 12%. It was determined that N rostellata is the most prone to deformation, therefore, from the bioindicative point of view, it is the most valuable species of periphytic diatoms among those studied.
Biogeochemical drivers of methane dynamics in the water column of Georgian Bay’s embayment, Lake Huron
Methane (CH4) production in oxygenated freshwater systems remains an active area of research in biogeochemistry. This study investigates CH4 dynamics in Honey Harbour’s North Bay, a stratified freshwater oligotrophic embayment of Georgian Bay (Lake Huron), by integrating microbial community analyses, and geochemical measurements. The field study was conducted in 2021, with four sampling campaigns carried out during the months of July, August, September, and October. During stable stratification, CH4 is present in oxic surface water with a maximum of 4.69 μg/L in September. The abundance of Synechococcus in surface waters indicates that CH4 formation may be driven by methylphosphonate (MPn) degradation under phosphorus limitation conditions. Additionally, methanogenic archaea were detected in oxic waters, indicating possible methanogenesis in oxic surface freshwaters. The CH4 oxidation possibly was supported by Fe- and Mn-reducing bacteria such as Geothrix and Methylobacter, which increased at depths below chemocline. Redundancy analysis (RDA) demonstrated strong positive correlations between CH4, photosynthetically active radiation (PAR), and microbes linked to CH4 cycling. Our study shows that CH4 production in surface waters is influenced by phototrophic and archaeal activity, whereas deeper waters exhibit CH4 oxidation coupled to metal cycling and Fe- and Mn-reducing bacteria. This study provides novel insights into microbial and geochemical interactions regulating CH4 emissions in oligotrophic freshwaters of Georgian Bay embayment.
A multi-stressor environment impairs the photosynthetic performance of Virescentia viride-brasiliensis (Batrachospermales, Rhodophyta)
Red algae belonging to Batrachospermales are important contributors to the energy input of lotic ecosystems. Given the importance of these algae for the lotic food web, we tested the photosynthetic performance of a relatively widespread and sensitive species (Virescentia viride-brasiliensis) in multi-stressor scenarios. Experiments were performed by exposing algal samples to three nominal concentrations (0.05 mg/L, 0.6 mg/L, and 1.2 mg/L) of tebuthiuron, a commonly used pesticide in Brazil, combined with three projected temperatures due to climate change (21.6ºC, 23.9ºC, and 26ºC). We observed a decrease in photosynthetic yield (Y(II)), regulated energy dissipation (Y(NPQ)), net photosynthetic rate (NPR), and dark respiration rate (DRR), while an increase in non-regulated energy dissipation (Y(NO)) was recorded, all of which indicate stress responses. Furthermore, we observed a dose-dependence relationship in which the negative effects increased with increasing tebuthiuron concentrations and in the scenario with a more severe temperature increase (26ºC). The high sensitivity of V. viride-brasiliensis to tebuthiuron highlights its potential bioindicator status because the tebuthiuron concentration accepted as safe for drinking water (0.05 mg/L) was sufficient to decrease its photosynthetic yield. Ultimately, these results show the importance of managing pesticide usage, especially considering the simultaneous occurrence of global warming.
MTA Centre for Ecological Research, Institute of Ecology and Botany
Movement and habitat use of native and non-native small benthic fish in a high conservation value agricultural environment
Despite the considerable progress that has been made in the field of taxonomy and genetics of freshwater fish, there is still a paucity of knowledge regarding their ecology and behaviour. We used PIT-telemetry to study movement and habitat use of native and non-native benthic fish species in a spring-fed irrigation stream, subject to seasonal macrophyte removal, in a rice field in North-Western Italy. This anthropogenically managed environment constitutes a habitat of high conservation value for some important endemisms, while hosting several non-native species. Fish were tracked both using manual tracking and stationary PIT-antennas, and telemetry data was complemented with catch data from electrofishing. The native P. bonelli and the non-native M. anguillicaudatus were tracked in sufficient numbers to allow quantitative analysis. While successfully tracked in the study area, both species were mostly stationary, but some fish registered movements in the study area of several hundred meters. M. anguillicaudatus showed a tendency of greater movements. With time, most fish disappeared from the study area but no direct migratory movement was detected. M. anguillicaudatus showed a clear preference for macrophyte-covered substrates while P. bonelli were frequently tracked both among macrophytes and on gravel substrates. Electrofishing data showed higher fish abundance in reaches subject to only partial macrophyte removal (fish-friendly management) compared to those subject to standard removal. Overall, movement seems to be an integral part of the ecology of benthic fish in this system, where vegetation appears to structure their spatial behavior.
Consequences of riparian forest invasions by alien plants for litter decomposition in small streams and ponds
Riparian forests play a crucial role in aquatic ecosystems by regulating light, temperature, channel stability and nutrient cycling. However, these forests are highly vulnerable to invasion by alien plant species, which can alter leaf litter inputs and decomposition dynamics, thereby impacting freshwater ecosystem functions. This study explores the decomposition rates of native black alder (Alnus glutinosa) and two riparian invaders, Japanese knotweed (Fallopia japonica) and Canada goldenrod (Solidago canadensis), in both headwater streams and pond mesocosms in Central Europe. We conducted experiments with 169 litter bags to assess decomposition rates and test the home-field advantage hypothesis. The hypothesis assumes that native litter decomposes faster due to the evolutionary adaptation of local decomposer communities. We found that invasive S. canadensis decomposed significantly faster than native A. glutinosa in both lotic and lentic environments. On the other hand, invasive F. japonica decomposed at a comparable rate (streams) or at a slower rate (ponds) than the native species. These findings contradict the home-field advantage hypothesis, suggesting that decomposition rates are primarily driven by litter nutrient content rather than geographic origin. The rapid breakdown of S. canadensis is likely driven by the low C:P ratio of its litter. The rapid decomposition of this litter may lead to short-term nutrient boosts that are quickly lost due to microbial activity, whereas the slow decomposition of F. japonica may limit immediate nutrient availability but extend their accessibility over longer periods. Overall, the invasion of riparian zones by species with litter traits distinct from those of native species can disrupt ecosystem processes, leading to cascading effects on aquatic food webs and nutrient cycling. Understanding the effects of riparian forest invasions on organic matter processing is essential for managing biodiversity and maintaining ecosystem integrity in freshwater environments.
Phytoplankton functional group dynamics and environmental drivers in a tropical monomictic lake (Lake Yambo, Philippines)
Tropical monomictic lakes, characterized by a single annual mixing event and prolonged stratification, are particularly sensitive to climatic and anthropogenic pressures. Lake Yambo, a tropical monomictic lake in the Philippines, exemplifies such systems, with stratification prevailing during the southwest monsoon and full lake mixing occurring during the northeast monsoon. This study examined vertical and seasonal variations in environmental conditions and phytoplankton functional group composition in Lake Yambo to assess how seasonal stratification and mixing affect functional groups’ vertical structure. Monthly sampling from March 2024 to February 2025 was conducted from the subsurface to 30 meters at 5-meter intervals. In situ measurements of water temperature, dissolved oxygen, pH, and nitrate (NO₃⁻) were obtained using multiparameter probes, while chlorophyll-a, ammonia, and total phosphorus were analyzed in the laboratory. Phytoplankton samples were collected, identified, and counted, with species comprising at least 5% of the total phytoplankton biomass per period classified into their respective functional groups. Lake Yambo exhibited meso-eutrophic conditions characterized by high total phosphorus concentrations but comparatively low chlorophyll-a levels, suggesting that phytoplankton growth is likely limited by nitrogen availability. Seasonal patterns governed thermal stratification and mixing, which, in turn, regulated vertical nutrient gradients. Stratified conditions during the southwest monsoon led to nutrient trapping and hypolimnetic anoxia, while northeast monsoon mixing redistributed nutrients, particularly NO₃⁻. These transitions strongly influenced the functional group composition. Seven dominant functional groups (B, F, G, H1, J, LO, and P) comprised 81% to 97% of the total phytoplankton biomass. Most functional groups declined with depth, but seasonal and vertical variations were distinct: Group G and H1 thrived in warmer surface waters with low nitrate concentrations. Groups J and LO were associated with cooler, nitrate-enriched surface layers during peak mixing, while Groups B, F, and P were more abundant at deeper layers under the same conditions. These findings support the hypothesis that seasonally driven stratification and mixing in tropical monomictic lakes structure vertical nutrient availability and shape phytoplankton functional group dynamics. Notably, the bloom of Group H1 during post-peak mixing under extreme nitrogen limitation and elevated temperatures poses a health risk, as this group’s descriptor taxon, Dolichospermum, can produce cyanotoxins. Thus, tropical monomictic lakes experiencing greater eutrophication may face increased risks of these toxic blooms. As a representative tropical monomictic system, Lake Yambo offers valuable insights into how similar systems respond to seasonal mixing and nutrient limitations, providing a framework for understanding and managing ecological risks in these environments.
A curious case: caddisfly cases built from brick and sewage overflow microplastics
Caddisflies larvae have been constructing cases made from vegetation or sediment grains for millions of years, but in the Anthropocene many alternative building materials have become available for caddisfly larvae. We collected caddisfly cases in three distinctive locations in The Netherlands, differing in degree of urbanization and pollution from sewage overflows. This resulted in a total of 1121 caddisfly cases, of which 311 presumably contained artificial material. Our results show that microplastics (MPs) from sewage overflows, along with littered bricks -whether from masonry waste in urban areas or historic dumping for streambank protection- affect how caddisfly larvae construct their cases. In the most polluted stream, more than half of all cases were found to include artificial material. The inclusion of masonry waste and MPs by the larvae as building and ballast material might alter the specific weight of the cases, which may influence the caddisfly larvae's functioning and behaviour. This is the first time a sewage overflow is directly linked to the inclusion of MPs in cases by caddisfly larvae and actions should be taken to minimize pollution from these overflows. Especially the MP load of sewage overflows may impact both the aquatic and the terrestrial ecosystem, as caddisfly larvae have a key role in the food chain and may transport these plastics into a broad and diverse food web. Sewage overflow events are expected to increase due to climate change, and it is expected that there will be three times as much human-made mass than dry biomass on Earth in 2040. This will, besides many other effects, impact caddisfly case construction in an even more dramatic way than is the case today.
The effects of microplastics size and type on entrapment by freshwater macrophytes under vertical and lateral deposition
Marine and freshwater macrophytes are known to filter off microplastics from the water column; however, the effects of microplastic size and type on their retention by different macrophytes species have yet to be investigated. Here we tested the retention of different sizes and types of microplastics, introduced under two flow regimes (vertical deposition in still water and lateral deposition in a unidirectional current), by two submerged macrophyte species, Hydrilla verticillata and Mayaca fluviatilis, using ex situ experiments. Microplastics entrapment efficiency in macrophytes was determined by calibrating the dry weight (DW) of the plant and analysing the characteristics of each macrophyte species via a comparison of their leaf outer-edge perimeter-to-area ratio (P:A). The entrapment efficiency of macrophytes was higher in still water than in moving water. Hydrilla verticillata had greater average leaf surface area and retained the most polyethylene terephthalate (PET) of size 800-1000 μm under both lateral deposition in moving water (1.75±0.11 g) and vertical deposition in still water (2.85±0.24 g). Conversely, M. fluviatilis had greater P:A, surface area, and high surface cellulose and retained the most PET of size 600-800 μm in both moving (0.73±0.07 g) and still (0.92±0.159 g) water. Our findings highlight the influence of microplastic size and material type, macrophyte morphology and surface area, and water flow conditions in determining the entrapment rate of microplastics by macrophytes.
Mississippi River-floodplain connectivity level mediates fish assemblage dynamics
The life histories of many Louisiana fishes are tied to the timing, magnitude, and duration of the Mississippi River flood pulse. Anthropogenic modifications designed to control and restrict flood waters have decoupled Louisiana’s floodplains from the seasonal flood pulse, influencing the aquatic food web. Culvert and rock weir repair within the Richard K. Yancey Wildlife Management Area aims to improve water quality and maintain appropriate water depth for native Louisiana fishes. In this study we conducted high-resolution imaging sonar (ARIS Explorer 3000) monitoring of the floodplain fish assemblage across seasons prior to hydrologic restoration. Imaging sonars may be used to obtain quantitative ecological and behavioral information without the selectivity biases of traditional techniques through the recording of continuous video-like datasets that are not constrained by environmental factors such as turbidity. Our first objective was to test the hypothesis that seasonal inundation levels and proximity to the Mississippi River affect the abundance and size class distribution of the floodplain-associated fish assemblage. Our second objective was to characterize species composition and ecological function of each acoustically-detected size class using historical fisheries datasets collected by the Louisiana Department of Wildlife and Fisheries. To do so, we employed the multi-gear mean standardization technique for standardizing catch per unit effort of passive and active gear types used within the historical dataset in order to produce a non-exhaustive list of potentially recorded species by the imaging sonar. Our study demonstrated a size class dependent use of floodplain habitats mediated by inundation level, but not the distance from the Mississippi River. Our results illustrated a trend of increased detections of all size classes during high-water connected-spring and summer periods, as well as during disconnected-summer periods immediately following the seasonal flood pulse. Continued monitoring of the fish assemblage will provide additional data to better describe the complex dynamic patterns the floodplain fish assemblage may exhibit in response to the seasonal flood pulse and hydrologic restoration efforts.
First report of non-marine ostracods (Crustacea, Ostracoda) from the Dahlak Archipelago (Eritrea), with the description of two new species
The information on Recent non-marine ostracod faunas of the north-eastern part of the Afrotropical region is still limited. Here we report the first record of ostracods from the Dahlak Archipelago, a group of small islands located in the southern part of the Red Sea off the Eritrean coast. Specimens were obtained by hatching in the laboratory of diapausing eggs occurring in dried mud collected in temporary freshwater ponds, following the so-called “Sars’ method”. A total of five species were found, including two species new to science, of which four belong to the family Cyprididae (Cypris galefensis, Plesiocypridopsis newtoni, Heterocypris sp., and Chrissia martensi n.sp.) and one to the family Ilyocyprididae (Ilyocypris dahlakensis n.sp.). A detailed description of the morphology of valves and soft parts is given, and COX1 sequences were obtained for four species. Cypris galefensis was so far only known for its type locality in Somalia with a population containing both males and females, whereas our samples consisted exclusively of females. Plesiocypridopsis newtoni, a species characterised by a wide geographic distribution and previously known to occur also in the Afrotropical region, shows marked variability in the prehensile palps of males, as evidenced by comparing the specimens from this study with descriptions available in the literature. The genus Heterocypris (with 15 species) and the genera of the two new species described here, Chrissia (with 17 species) and Ilyocypris (with four species), have been previously reported from this biogeographic region as well. The specimens analysed of Chrissia martensi n.sp. were all females, none of which had sperm inside the carapace, indicating the possibility of parthenogenetic reproduction in this species. A peculiar sexual dimorphism in the valve morphology characterises Ilyocypris dahlakensis n.sp., with females having a straight posterior margin, forming a right angle at the ventral anterior edge. Rehydration of dry sediments collected from arid areas where wet periods are short and often unpredictable has proven to be a successful method for describing aquatic invertebrate biodiversity.
Revisiting lakes within the Rideau Canal system (Ontario, Canada) to assess the impacts of multiple environmental stressors over the past ~25 years using diatom-based paleolimnology
Diatom-based paleolimnological studies conducted ~25 years ago on five lakes (i.e., Big Rideau, Upper Rideau, Lower Rideau, Indian and Otter lakes) within the Rideau Canal system (Ontario, Canada) tracked extensive catchment disturbances related to canal construction (starting ca. 1828). Over the past three decades, these lakes have experienced additional environmental stressors including invasive zebra mussels and accelerated climate warming, warranting a paleolimnological re-assessment. We examine diatom compositional changes and visible range spectroscopy-inferred chlorophyll-a (VRS-Chla) trends over the past >200 years from sediment cores collected in 2019-2020 from these same lakes, with the aim of assessing environmental changes registered in these records since the original studies were undertaken ~25-30 years ago. Despite large-scale cultural disturbances, including extensive deforestation and flooding for canal construction, the most ecologically notable diatom changes in all sediment records occurred in the past ~25-30 years, and coincided with increases in VRS-Chla. During this recent period, small cyclotelloid and elongate planktonic diatoms increased in relative abundance, while large-celled Aulacoseira taxa declined. Exceptions to this trend include Upper Rideau Lake, where planktonic diatoms were scarce throughout the core and shifts occurred among benthic taxa, and Big Rideau Lake, which has a large littoral zone, where epiphytic diatoms became prominent in the past decade. These recent diatom changes could not be explained by nutrient enrichment, as measured total phosphorus (TP) concentrations have declined significantly since the 1970s. Increases in small planktonic taxa in some of the lakes also pre-date the ca. 1990 arrival of zebra mussels. We conclude that these recent changes were best explained by regional warming and declining wind speed resulting in new lake physical regimes. Such climate-driven changes are also consistent with the recent development of cyanobacterial blooms in these lakes, despite declining nutrient levels.
A survey of bdelloid rotifers from coastal ponds in Southern Norway
We report the results of the first survey of bdelloid rotifers, microscopic aquatic animals, in continental Norway, collected from coastal ponds in the Southern part of the country in Autumn 2021, using a morphological approach in species identification. Out of 25 ponds, 19 bdelloid species were found, ten in water samples and another nine in limno-terrestrial habitats just above the waterline of the ponds. Seven of the species are new records for mainland Norway. Three species could be identified to genus level only and may be novel taxa, not only for Norway but for science: further studies are needed on these animals to clarify their taxonomic identity. We also obtained COI sequences from 194 animals of eight of the species to compare them with what is known in GenBank in a phylogenetic context and confirm the reliability of morphological identification. This data contributes to our understanding of the taxonomic and biogeographic diversity of bdelloid rotifers in Norway. In addition, the newly available sequences increase the coverage of the reference library of bdelloid rotifers for future studies employing DNA metabarcoding.