The lacustrine sediment samples from a 47 cm-long core from the shelf area of the Vestfold Hills region, Antarctica, were studied. The core reached an age of 6.48 kyr BP at the bottom. The major objective of this study is to reconstruct the paleoclimatic changes during the Middle to Late Holocene, with special emphasis on the possible incursion of marine water into this inland lake. A very restricted range of 13 diatom species was identified, which provides evidence toward lacustrine environmental conditions, with marine intrusion events and climatic changes in the area. These 13 species are grouped mainly under nine genera: Amphora Ehrenberg ex K & uuml;tzing, 1844 (1 species); Cocconeis Ehrenberg, 1836 (1 species); Diploneis Ehrenberg ex Cleve, 1894 (2 species); Fragilariopsis Hustedt, 1913 (2 species); Paralia Heiberg, 1863 (1 species); Navicula Bory, 1822 (3 species); Pinnularia Ehrenberg, 1843 (1 species); Thalassiosira Cleve, 1873 (1 species); and Trachyneis P.T.Cleve, 1894 (1 species). The relative percentage of total marine diatoms, as well as the changes in the sedimentation rate, confirmed the marine influence in this lake during the Middle Holocene, which got lessened after ca. 4.5 kyr BP. This is also supported by the CONISS cluster analysis (considering abundance of species as variables), which shows two distinct zones divided around the same time. This can be correlated with the major Antarctic glacial retreat event ending at ca. 4 kyr BP.
A tribute to Raymond Rouch, a renowned researcher in groundwater ecology, focuses on scientific and cultural aspects of his work filled with new ideas and stimulating results addressed to the following topics: (a) the taxonomy and systematics of copepod crustaceans, particularly Harpacticoida and Gelyelloida, found in groundwater habitats; (b) the groundwater ecology, where innovative ideas, new methods of research, and scientific results helped to promote a modern new groundwater ecology; and (c) the insertion of a hydrogeology approach insofar as the research in ecology required identifying the origin and dynamics of groundwater flows in karst systems in particular. As an addition, the story of the famous Bou–Rouch pump is presented. The interest in various scientific fields reveals Rouch’s broad erudition. He was an excellent draftsman and expressed himself through painting, inspired by Max Ernst and Salvador Dali. The appreciation for the scientific work of Raymond Rouch by the community is illustrated through the dedication to him of 20 species named in his honor. Two annexes include Rouch’s list of publications and a list of the new taxa he described.
Integrating vertical and seasonal gradients into ecological monitoring is crucial for identifying biodiversity hotspots and understanding community dynamics in vulnerable high-Andean lakes. Benthic macroinvertebrates are sensitive indicators of ecological quality in high-altitude freshwater ecosystems, including tropical mountain lakes. We evaluated spatial and temporal patterns of benthic macroinvertebrate communities in the southern shallow basin (Lago Menor) of Lake Titicaca (Bolivia) along depth and hydrological gradients. Three bathymetry-defined biotopes were sampled (A: shallow, B: intermediate, C: deep) during three hydrological periods (dry-to-wet transition, wet season, and wet-to-dry transition). We measured physicochemical variables, submerged macrophyte biomass, Chara sp. biomass, and macroinvertebrate assemblages; only Chara sp. was recorded among charophytes. Community composition and structure were analyzed using multivariate ordination, community metrics (richness, Shannon diversity, abundance, dominance), and regression models. From 38 taxa, Amphipoda and Gastropoda dominated. Richness, diversity, and abundance declined significantly with depth, while macrophyte biomass, highest in shallow vegetated sites, was positively associated with these metrics. Chara sp. peaked at intermediate depths and was positively associated with Hyalella longipalma, suggesting a structural role in deeper, less competitive habitats. Community differentiation was strongest between shallow and deep biotopes during the dry-to-wet transition (ANOSIM R = 0.73), whereas a trend toward homogenization emerged during the wet-to-dry transition. Redundancy analysis indicated that pH, conductivity, and vegetation biomass partially explained community variation. Overall, our results highlight shallow vegetated habitats as biodiversity hotspots and support integrating depth and seasonal gradients into monitoring frameworks for high-Andean lakes.
Aquaponics represents an eco-friendly and resource-efficient approach to food production by integrating aquaculture and hydroponic farming in a synergistic cycle. In this system, the waste generated by fish serves as a nutrient source for plants, which in turn contribute to water filtration and purification. This paper introduces a smart aquaponics model, enhanced with evolutionary optimization techniques and supported by IoT-based monitoring. An ESP32 microcontroller is deployed as the central processing unit, connected to various sensors including DHT12 for temperature and humidity, TDS for measuring dissolved solids, and pH sensors to track water quality parameters. Sensor readings are continuously transmitted to a cloud-based platform, allowing for remote access, data analytics, and adaptive system control. This study evaluates the performance of three optimization algorithms, Genetic Algorithm (GA), Simulated Annealing (SA) and Particle Swarm Optimization (PSO) in enhancing critical parameters such as plant growth efficiency and overall system robustness. The findings emphasize the practical value of integrating IoT and computational intelligence in advancing sustainable agriculture through smart aquaponics systems.
Hypselobarbus kurali (Red-tailed Barb) is a commercially important food fish that is endemic to the Western Ghats biodiversity hotspot and is extensively harvested from rivers in the state of Kerala, India. The present study investigates the fishery, demographic characteristics, and exploitation pattern of H. kurali, in five river systems situated within the Southern Western Ghats. The monthly catches of this species from different landing centres across the rivers ranged from 52.5 (January) to 133.8 kg (July). The estimated growth parameters of H. kurali include an asymptotic length (L infinity) ranging between 263.55 and 368.55 mm and growth coefficient (K) varying from 0.42 to 0.82 yr-1 across different rivers. The total mortality (Z) ranged between 0.90 yr-1 and 2.17 yr-1 while the fishing mortality (F) was estimated between 0.41 yr-1 and 1.37 yr-1. The fishing mortality rate observed for H. kurali in the Periyar River of 1.37 yr-1 seems to be among the highest ever documented for this species. This rate raises concerns about a potentially indiscriminate level of exploitation by local fishers in the river. The current exploitation rate (E), which varies from 0.44 to 0.63 yr-1, exceeds the optimum exploitation level (E = 0.47) in Periyar, Pampa and Muvatupuzha rivers. It indicates that unmanaged fishing may have resulted in unsustainable exploitation, making this cyprinid population in Western Ghats rivers at risk of an imminent collapse. Enforcing measures like implementing fishing closures during spawning seasons, imposing restrictions on mesh sizes and establishing non-fishing zones can contribute to sustainable fisheries management of H. kurali.
Recent molecular studies have highlighted the taxonomical complexity of the Eurasian minnows Phoxinus spp, pointing out their multiple endemic species to their respective catchments, and also the multiple translocations between drainages. Here, we report the first record of the Italian minnow Phoxinus lumaireul in France: a male specimen was caught in the Lake Geneva at Publier (Haute-Savoie department) the 31st May 2010 during an elecrofishing survey monitored by the ONEMA. The identification was done from a picture, according to morphological observations and the nuptial colouration pattern, in comparison with P. lumaireul from the Po catchment. We then attest the presence of a third minnow species in the Lake Geneva basin, in addition to P. csikii and P. septimaniae. The nuptial colouration pattern of P. lumaireul is diagnosable by very little developed nuptial tubercles on the head, pectoral fins yellowish hyaline, a green bluish stripe on Z3 until the caudal peduncle origin and black beyond, Z4 green yellowish and a belly shiny red from the throat to the caudal fin base for males, and pectoral, pelvic and anal fin bases pinkish, yellow spot on the operculum, Z4 slightly golden and Z5 white for female. Our morphological identification corroborates a molecular study from the Swiss part of the Lake Geneva basin. Phoxinus lumaireul is then the seventh and the first non-native minnow species occurring in France. Its introduction through human translocations seems to be ancient. We also discussed about ecological impacts for French and Swiss managers.
The bloody-red shrimp Hemimysis anomala, a Ponto-Caspian mysid, has invaded many large lakes in Europe and North America. It exhibits a pronounced seasonal behaviour, forming massive winter swarms (WS) whose dynamics are likely driven by different processes implying reproduction capacities, responses to resource availability and/or predation pressure. We hypothesize that these different processes may not be mutually exclusive but could rather be successively involved in explaining the formation and disappearance of WS. We also expected that water temperature may be a major indirect driver of WS dynamics by indirectly controlling the above processes. To test these hypotheses, we used a combination of high-frequency video monitoring (through acoustic and visible-infrared cameras), direct diving observations, and diet analyses to track the dynamics of a WS of H. anomala in Lake Geneva at different time-scales. Our results reveal adult-juvenile successions during swarm formation while swarm ending was associated to the presence of only juveniles suggesting an effective implication of reproduction for WS formation and possibly its collapse. Temperature had a negative indirect effect on H. anomala abundance during the WS collapse and was only partly mediated by the littoral returns of perch (Perca fluviatilis) for which active predation was clearly identified from videos.
In a mesocosm experiment, we simultaneously evaluated the responses of phytoplankton, epiphyton, and epipelon to combined nitrogen and phosphorus enrichment and its subsequent interruption. The short-term experiment (35 days) was conducted in a shallow mesotrophic lake, with sampling performed after a phase of daily nutrient enrichment and again after a following a 20-day interruption. The enrichment phase shifted the system to eutrophic conditions, while the interruption returned it to mesotrophic status. Nutrient enrichment had a positive effect on phytoplankton biovolume, a negative effect on epiphyton, and no significant impact on epipelon. After 20 days without enrichment, phytoplankton biomass declined significantly, epipelon increased, and only minor changes were observed in epiphyton. Enrichment favored bloom-forming in the phytoplankton and species adapted to low-light conditions in both the epipelon and epiphyton. Filamentous forms, particularly Spirogyra, increased during the enrichment phase in the epiphyton and, following its interruption, in the phytoplankton. In conclusion, nutrient enrichment associated with phytoplankton blooms reduces the contribution of epipelon and epiphyton to the system, leading to loss of biomass, decreased diversity, and changes in species composition. Our findings demonstrated that nutrient enrichment could compromise the ecological function of periphyton in lake ecosystems.
We present a new version of a barcoding reference library dedicated to diatoms, Diat.barcode v12, with newly published sequences, annotated with ecological, and biological traits (size class, life forms, ecological guilds, etc) and curated by a college of experts. Diat.barcode incorporates rbcL data on all diatoms, though freshwater taxa are better represented. We used this library in two different areas, one where the taxonomic coverage of the library was good (mainland France) and another where it was poor (French Guyana) with about 320 diatom samples collected for river monitoring across both regions. We show that a direct bioinformatic assignment of environmental sequences to traits (ecological guilds, habitats, morphology) has great potential in French Guyana where species knowledge is poor and therefore the proportion of assigned environmental sequences is much lower (12.8%) than trait assignation (30%). We used co-correspondence analyses to show that, unlike mainland France where all species and trait assignation datasets were significantly correlated, in French Guyana only 7 out of 13 trait categories showed a significant correlation. This indicates a significant loss of ecological information through species assignment in French Guyana. Consequently, directly assigning environmental sequences to traits can be useful and provide more ecological information in regions with poor taxonomic knowledge because of the many rbcL sequences without taxonomic assignations.
The Peruca Reservoir, a critical karstic water resource in Dalmatia, Croatia, experiences significant water quality fluctuations influenced by rapid surface and groundwater recharge and climate change. This study develops a predictive framework utilizing a hybrid Graph Neural Network (GNN) and Transformer model to forecast key water quality parameters. Based on a dataset of monthly surface water quality measurements from 2019 to 2021, including water level, dissolved oxygen (DO), electrical conductivity (EC), pH, hardness, temperature, and precipitation, the model accurately predicts the Water Quality Index (WQI), DO, and EC (R-2 > 0.92 for 5-day forecasts). The analysis focuses on temporal water quality variations at a single monitoring station due to data limitations, with spatial resolution limited to inflow influences. Climate projections for 2050, assuming a 5% decrease in precipitation and a 1.7 degrees C temperature rise, indicate a potential decline in reservoir water levels by 0.75-1.17 meters and a summer WQI reduction to 67-70. The proposed model consistently outperforms benchmark Random Forest and Long Short-Term Memory (LSTM) models, demonstrating its robust predictive capability and providing crucial decision-support for the sustainable management of karstic reservoirs.
Comprehensively evaluating water quality is of great significance to lake environment management. In this study, we integrated field measurements and long-term Landsat-5/8 images to assess the water quality of Nansi Lake, one of the important water transport trunks of the east route of the South-to-North Water Diversion project in China. Results showed that water temperature of the lake in spring has risen by about 4.7 °C from 2013 to 2020. The COD Cr and TP both showed a downward trend while NH 3 N presented an upward trend in spring and autumn after 2014. The TN concentration showed a linear upward trend in autumn after 2014. Comprehensively, the WQI and TLI in both spring and autumn increased slightly from 2013 to 2015, decreased rapidly in 2016, and then presented a linear increase trend, indicating that the degree of water pollution in Nansi Lake has continued to increase since 2016, and the nutrient status has changed from mesotrophic to mild eutrophication. The concentration of COD Mn is highly positively correlated with COD Cr and both closely connect with the content of BOD5 and TP. The NH 3 N, TP and TN are covariant with each other. Remote sensing-based Chl a exhibited a gradual increase from about 10 mg/L in 1990 to 18.3 mg/L in 2005 and then linearly dropped and kept at around 10 mg/L after 2010. The change of water quality in Nansi Lake is highly correlated with the growth of population and the expansion of local fishery size, meaning a prolonged impact of social-economic development.
Nearly half of Türkiye's freshwater fish species are endemic, yet many face severe threats from anthropogenic pressures such as dam construction, pollution, habitat degradation, invasive species, and drought. Understanding the life history and reproductive biology of these species is essential for the conservation of native, particularly endemic, populations and for developing sustainable stock management strategies. The Anatolian khramulya ( Capoeta tinca ), an endemic benthic algae-scraping species, generally inhabits lotic systems and plays a key ecological role in riverine ecosystems. In this study, the population structure, growth, and reproductive characteristics of C. tinca were analyzed using specimens collected from the Devrez River between April 2020 and March 2021. Length–weight relationships showed positive allometric growth in females and isometric growth in males. The von Bertalanffy growth function indicated that females grew more slowly than males. Scale readings revealed maximum ages of 9+ years for females and 4+ years for males. The maturity ogives showed that 50% of females and males were sexually mature at 20.0 cm and 16.0 cm, respectively. C. tinca exhibited a protracted spawning season lasting from May to August, with a mean absolute fecundity of 10,419 ± 8811 oocytes. Fecundity was positively correlated with fork length, body weight, gonad weight, and age. The ongoing construction of the Devrez Kızlaryolu Dam represents a significant future threat to the ichthyofauna of the region. These findings emphasize the importance of incorporating species-specific reproductive and growth characteristics into regional conservation and management plans to sustain endemic fish populations in freshwater ecosystems.
Field investigations were carried out in mid-April for two years in road ditches located in the department of Indre (central France) to determine whether there was competition between Anisus spirorbis and Galba truncatula in habitats where the two species live together. Compared to control populations, the number of A. spirorbis living in a community was 70 per cent lower in 2023 and 59 per cent lower in 2024, while the density of G. truncatula showed no significant variation. Shell diameter ( A. spirorbis ) or shell height ( G. truncatula ) did not differ significantly between community and control snails. Laboratory studies were also conducted from March to June for two years by placing juvenile, pre-adult or adult planorbids in the presence of juvenile, pre-adult or adult G. truncatula in Petri dishes for 30 days. The life stage of G. truncatula had a significant influence on the survival of A. spirorbis . In pairwise-raised snails, this survival was significantly lower for juvenile planorbids than for pre-adults. In contrast, survival of adult planorbids was slightly lower than that noted in corresponding controls, while their reproductive activity was significantly lower. This interspecific competition between A. spirorbis and G. truncatula would not be due to a limitation in food resources because food was abundant in their natural habitat or breeding dishes. It might be due to the action of mucus and/or toxicity of faecal pellets excreted by adult G. truncatula .
Coregonines have specific ecological needs, making them potentially very vulnerable to changes in lake conditions. A contemporary concern is that many lakes worldwide are experiencing environmental changes due to anthropogenic pressure and climate warming. Here, we compiled long-term data of coregonine catches from 27 lakes from three continents in the northern hemisphere. Declines in catch were observed in 67% of the lakes during the first two decades of the 21 st century, with a significant trend (p-value<0.05) in 44% of the cases. An analysis to determine whether trends are globally linked to environmental conditions and specific lake attributes was carried out on 26 lakes for the period 2000–2019. Several local declines in catches had already been documented in the literature and are likely to be due to local forcing such as nutrients, species invasions and changes in fishing practices. Nevertheless, on a global scale, our results indicate that lakes, which exhibited a significant decrease in catch were larger and more nutrient-poor than other lakes. The rate of change in catches appeared to be related to the trophic state of the lake. The specific effect of warming is difficult to determine during the studied period. When warming occurred outside the period of egg incubation, decreasing trends were more frequently observed in nutrient-poor than in mesotrophic lakes. In conclusion, our findings suggest that achieving oligo- or ultraoligotrophic conditions, as required in developed countries to control phytoplankton blooms and enhance water quality, could pose significant challenges for future management of coregonine fisheries.
In this study, we report and describe of five adult pikeperch ( Sander lucioperca Linnaeus, 1758) specimens collected from the Keban Dam Lake (Euphrates-Tigris Basin) eastern-Anatolia of Türkiye. Samples caught by local fishermen during a routine gillnet fishery were brought to the laboratory for identification and detailed morphometric measurements. This appears to be the first documented record of S. lucioperca from Keban Dam Lake. In this context, it can be said that the entire Euphrates-Tigris basin is under threat of the spread of this species.
Marginal lagoons are natural nurseries of commercially important fish species and preferential habitats for sedentary and small-sized fish species. The composition and abundance of fish communities in seasonally isolated lagoons of the Turvo River, qualitative and quantitative changes in the dry and rainy seasons, as well as their relationship with environmental factors, were investigated. The material was sampled in both seasons in six marginal lagoons. Ichthyofauna was studied through species richness, diversity, evenness, qualitative and quantitative similarities, and ecological associations between samples and species. A total of 7457 specimens, distributed among 52 species, 40 genera, 19 families, and five orders, were recorded. The most abundant species were Astyanax lacustris , Serrapinnus heterodon , Pterygoplichthys ambrosettii , Hyphessobrycon eques , and Moenkhausia intermedia . Fish communities showed remarkable seasonality with the highest values of species richness and abundance in the rainy season. In both seasons, higher species richness was found in environments with the largest area and amount of macrophyte species. Canonical correspondence analysis revealed that water temperature and alkalinity were significantly associated with ichthyofauna structure. Despite adverse conditions in isolated seasonal lagoons, global fish diversity was high due to heterogeneous environmental conditions. These habitats must be considered priority areas for fish conservation and management.
Fisheries stock assessment is essential for sustainable freshwater fisheries management, and enhancing the management plans can improve the fisheries’ decision-making process. The present study assesses the status of fish assemblage aiming to provide recommendations for better fishery management in three Tunisian reservoirs: Lahjar, Kasseb and Siliana. Five surveys were conducted between March 2020 and June 2021 based on the European standard (CEN pr EN 14757), using the multi-mesh monofilament gillnets. This sampling method was applied to estimate species composition, abundance, yields, vertical distribution, and size structure. Eight species were caught in the reservoirs: Sander lucioperca, Chelon ramada, Mugil cephalus, Cyprinus carpio, Lucioberbus callensis, Rutilus rubilio, Scardinius erythrophtamlus , and Oreochromis niloticus. Fish abundance varied significantly among the sampling sites, seasons and depth. The highest catch per unit effort was observed in Lahjar Reservoir (820.08 ind.1000 m −2 / 162330.66 g.1000 m −2 ), followed by Siliana (161.59 ind.1000 m −2 / 28780.96 g.1000 m −2 ), while Kasseb Reservoir had the lowest values (4.17 ind.1000 m −2 /1393.27 g.1000 m −2 ), suggesting it may be in an overexploitation state. RDA indicates unbalanced fish communities in Lahjar and Siliana Reservoirs. The findings showed that fish biomass distribution was influenced by depth, with the majority of catches occurring in the upper water layers. To conclude, Siliana, and especially Kasseb Reservoir, requires support to improve fish productivity and maintain biodiversity.
Hydrological exchanges between rivers and groundwater are essential for many ecosystem processes: identifying their location requires a set of physical, chemical and biological indicators. Here, we describe Schellencandona rhodanensis sp. n . (Ostracoda, Candoninae), a species highly sensitive to hydrologic exchanges in river sediment. The new species is close to Schellencandona triquetra (Klie, 1936), but mainly differs in the shapes of the female genital lobe and the male hemipenis. The species is described from the Rhône River watershed, where it occurs in at least five tributaries. It is a stygobite species ( i.e. a groundwater specialist), occurring in both the main channel and associated wetlands, with a maximum abundance at depth of about 1 m below the sediment surface. While S. triquetra is collected in a wide range of groundwater habitats, S. rhodanensis sp. n . is mostly restricted to river interstitial habitats fed by groundwater. It can be used as a biological indicator of interstitial habitat stability and to locate groundwater upwellings in river bed sediment.
Amphibious plants attract much attention due to their unique ability to live in aquatic and terrestrial environments and sustain abrupt changes of water regime in the habitat. They may colonise habitats with pronounced water level fluctuations and water /dry land interface areas. Water and air differ in many aspects, like density, buoyancy, light and thermal conditions, as well as humidity and diffusion of gases, including oxygen and carbon dioxide, that all affect plant growth and development. The evolution of amphibious plant species resulted in high phenotypic plasticity that is manifested as a variety of ecophenes performing optimally in contrasting conditions. The most important adaptations are heterophylly and/or different life forms that differ at morphological, anatomical, biochemical, and physiological levels. These adaptations comprise the wide span of traits that are found in submerged and terrestrial plant species. The plasticity of amphibious plant species offers a potential to colonise water bodies where hydrology is affected by climate changes and present a unique model system where different scientific aspects of plants may be studied in genetically identical specimens.
Sulfate is found naturally in the aquatic environments, but due to various anthropogenic activities the sulfate concentrations in surface waters have increased globally. High levels of sulfate can cause adverse effects on aquatic organisms. In this study we explored the effects of sulfate on the reproduction of two coregonine species, whitefish (Coregonus lavaretus (L.)) and vendace (Coregonus albula (L.)), in Baltic Sea brackish water and soft boreal freshwater. The chronic toxicity tests lasted from fertilization to hatching of the larvae, endpoints being embryonic and larval survival, and size of newly hatched larvae. The chronic 196-214-day tests were conducted in different sodium sulfate (Na2SO4) solutions at water temperatures simulating natural conditions during the egg incubation from autumn to spring. The separate fertilization tests were carried out to measure fertilization success (%). The fertilization and early embryonic phase were found to be the most sensitive periods for sulfate toxicity. The survival in late embryonic phase, hatching and 5-day larval phase was high (>80%). In the acute fertilization tests with brackish water populations, the LC50-values were between 2554 and 2575 mg/L and with freshwater populations between 1107 and 1230 mg/L of sulfate. In the chronic experiments from fertilization to hatching the LC10-values for brackish water populations were between 1800 and 1820 mg/L and for freshwater populations between 335 and 624 mg/L of sulfate. The tolerance for sulfate in freshwater coregonines was significantly lower than brackish water coregonines, but it was in similar range as to what has been observed in other freshwater species.
