Lake Complex Research Articles

Changes in the Buffer Properties of the Restored Lake Complex

Changes in the Buffer Properties of the Restored Lake Complex

Changes in submerged macrophyte diversity, coverage and biomass in a biosphere reserve site after 20 years: A plea for conservation efforts

The conservation of submerged vegetation is crucial in the functioning of aquatic ecosystems. We have assessed, by means of subaquatic quantitative sampling transects, the current status of the hydrophytic flora in 14 lakes in the Lagunas de Ruidera Natural Park, a Biosphere Reserve site in central Spain, surrounded by a semi-arid landscape. The conforming lakes have endured several anthropic pressures for decades (e.g., eutrophication, land-use changes, etc.). By comparing the current with the former status (20 years ago) of hydrophytes in the natural park, substantial negative (species richness loss, decrease in submerged meadow coverage, particularly in the upstream lakes) and positive (natural recovery of meadows after the cut-off of sudden disturbances caused by point pollution sources, improving of trophic state in some lakes, no presence of exotic hydrophytes) changes in the lakes were noticed. We have analyzed that the disappearance of all the hydrophyte (mainly charophytes) stands would represent the loss of ecosystem services. For example, up to 70 t CH4 might be released from the charophyte detritus, an internal pool of phosphorus (as high as 1400 mgP/m2) stored in the charophytes stands could be liberated. Some lakes require special measures, but overall, to preserve this lake complex, and other similar ones, we propose to study, in detail, the causes of submerged vegetation deterioration (focusing on the presence of pesticides –in water and sediments-, and other reasons) to assess the ecological risks, to protect the groundwater resources, preventing the lakes from receiving surficial point and non-point sources of pollution.

Small Paa Frog and Marbled Cascade Frog are not endemic to Nepal: a response to Tachamo-Shah et al. 2023

Response to ‘Wetland biodiversity of Ramaroshan Lake complex: a need for conservation’ on JoTT Vol 16 issue 12 <https://doi.org/10.11609/jott.7918.15.12.24299-24320>. Many information in the article promising, highlighting the additional attention the area should receive for conservation. However, there are some aspects, particularly that are related to conservation status and endemism of amphibian species which is misleading, making me to realize to write this response.

Spatio-Temporal Variation of Cyanobacteria Blooms in Taihu Lake Using Multiple Remote Sensing Indices and Machine Learning

In view of the ecological threat posed by cyanobacteria blooms in Taihu Lake (China), this paper presents a study on the area of cyanobacteria extent based on MODIS data using the quantum particle swarm optimization–random forest (QPSO-RF) machine learning algorithm. This paper selects multiple remote sensing input indices that can represent the characteristics of the primary underlying type in Taihu Lake. The proposed method performs best, with an F1 score of 0.91–0.98. Based on this method, the spatio-temporal variation of cyanobacteria blooms in the Taihu Lake complex was analyzed. During 2010–2022, the average area of cyanobacteria blooms in Taihu Lake increased slightly. Severe-scale cyanobacteria blooms occurred in 2015–2019. Cyanobacteria blooms were normally concentrated from May to November. However, the most prolonged extended duration occurred in 2017, lasting for eight months. Spatially, cyanobacteria blooms were mainly identified in the northwestern part of Taihu Lake, with an average occurrence frequency of about 10.0%. The cyanobacteria blooms often began to grow in the northwestern part of the lake and then spread to the Center of the Lake, and also dissipated earliest in the northwestern part of the lake. Our study is also beneficial for monitoring the growth of cyanobacteria blooms in other similar large lakes in long time series.

Hydrochemistry and Irrigation Quality of High-Altitude Lakes: A Case Study of the Ramaroshan Lake Complex, Nepal Himalayas

The Ramaroshan Lake Complex (RLC) in Sudurpaschim Province, Nepal, is a Himalayan lake cluster that holds significant ecological, economic, religious, and esthetic importance. This study aimed to provide a comprehensive characterization of the hydrochemical properties of water within the RLC and assess its suitability for irrigation purposes. A total of 38 water samples were collected from seven different lakes of the complex. The physicochemical parameters and major ions were then analyzed. The water samples from the RLC were alkaline, and based on total hardness, they ranged from soft to moderately hard categories. The presence of major ions included the following: Ca2+ > Na+ > Mg2+ > K+ > Fe3+ > NH4+ and HCO3− > Cl− > SO42− > NO3− > PO43−. The alkaline earth metals (Ca2+ and Mg2+) dominated the alkali metals (Na+ and K+) and weak acids (HCO3−) dominated the strong acids (Cl− and SO42−). The dominant hydrochemical facies of the lake water was a Ca-HCO3 type indicating a calcium carbonate type of lithology. Carbonate rock weathering was the most dominant process in influencing the hydrochemistry of the water. A high ratio of (Ca2++ Mg2+)/Tz+ and a lower ratio of (Na+ + K+)/Tz+ revealed the dominance of Ca2+ and Mg2+ resulting from carbonate weathering, with little contribution from silicate weathering. Different irrigation indices revealed the suitability of the RLC water for irrigation. The insights derived from this study are pivotal in safeguarding water quality and bolstering sustainability efforts. The study also furnishes foundational data crucial to an array of stakeholders including researchers and policymakers and significantly contributes to advancing water management strategies and fostering ecosystem conservation in the Himalayan freshwater lakes, particularly in the face of the overarching challenge posed by global climate change.

Wetland biodiversity of Ramaroshan Lake complex: a need for conservation

The Ramaroshan Lake Complex, situated in the mid-hills of Sudurpaschim Province, is renowned for its scenic beauty, yet there is a notable dearth of information regarding its biodiversity and ecological status. This study represents the first systematic examination of seasonal variations in water quality parameters and biodiversity encompassing aquatic macroinvertebrates, fishes, birds, herpetofauna, mammals, and macrophytes, as well as the surrounding vegetation within the complex, spanning the winters and summers of 2018 and 2019. Among the twenty water quality parameters investigated, thirteen displayed significant seasonal differences across the lakes (p <0.05), with Batula and Ramaroshan lakes exhibiting elevated nutrient levels. Lamadaya Lake stood out with a highly diverse macroinvertebrate community compared to other lakes, while overall, the study recorded 45 aquatic macroinvertebrate families, three fish species, 79 bird species, 12 herpetofauna species, 12 mammal species, and 26 macrophyte species within the complex. Additionally, the surrounding vegetation comprised 193 distinct plant species. Notably, the complex currently hosts 14 IUCN Red List species, including Near Threatened (5), Vulnerable (5), Critically Endangered (1), and Endangered (3) species, as well as five migratory wetland bird species, underscoring its significance for wildlife conservation. Given the diverse and cross-cutting nature of wetlands, the development of science-based policies and coordinated efforts among central, provincial, and local governments are essential for the preservation and sustainable management of these vital ecosystems.

Evaluation of survival estimates generated from tracking downstream migrating juvenile sea lamprey (Petromyzon marinus) with a miniature acoustic telemetry tag

Fish that undertake juvenile migration pass through habitats that vary in mortality risk. The ability to identify regions of persistently low survival would improve fishery management. We conducted a field study combined with predictive modeling of survival in downstream migrating juvenile sea lamprey using a new micro-acoustic telemetry tag designed for implantation into small, slender-bodied fishes. Detection data were collected from eight receivers placed across a coastal riverine–wetland–lake complex. Juvenile sea lamprey initiated downstream movement near nautical twilight, stopped frequently, and were more likely to move during high river discharge. Estimated survival was highest in the riverine reach, declined through the river–wetland complex, and dropped precipitously in the drowned rivermouth lake. However, the high transmission rate and resulting short battery life of the microtransmitters (as configured) likely resulted in missed detections in the lower reaches. Simulation analyses suggested survival estimation could be improved by increasing the number of tagged lamprey and staggering release locations. We offer practical recommendations for the use of this new transmitter in field studies with small anguilliform fish.

Waterbird community changes in the Wilderness Lakes, South Africa (Part 1 of 3): Herbivores and omnivores

Global and regional degradation and loss of aquatic systems can negatively affect wetland-dependent waterbirds. The Wilderness Lakes Complex in South Africa, which incorporates the Wilderness Ramsar site, supports populations of 68 waterbird species including eight which periodically occur in globally significant (1% population) numbers. The study aimed to document long-term spatial and temporal (including seasonal) patterns of abundance of herbivorous waterbirds in the Wilderness Lakes Complex, and where possible identify potential causes for observed trends. The abundance of waterbirds on these wetlands was determined biannually from 1992 to 2019, with counts conducted from a boat following a standardised route. Historical abundance data from the 1980s was also used to describe long-term abundance changes. Observed seasonality of four herbivorous waterbirds differed from published accounts. Long-term abundance trends indicated a combination of declining, increasing and stable populations which, in several instances, differed from regional (southern African) assessments. Significant long-term decreases have occurred in five herbivorous species in the lakes complex (Common Moorhen Gallinula chloropus, Red-knobbed Coot Fulica cristata, Yellow-billed Duck Anas undulata, Cape Shoveler Anas smithii, Cape Teal Anas capensis), whereas increases have occurred in two species (Spur-winged Goose Plectropterus gambensis, Egyptian Goose Alopochen aegyptiaca). Similar types of change occurred across multiple waterbodies, and in different seasons. The similarity of trends in spatially separated wetlands suggested either high interconnectivity of populations between wetland systems and/or some drivers of change of mobile species being broad scaled and regional, rather than system specific. Local reasons for changes potentially include increasing extent of cultivated fields, a proliferation of emergent macrophytes and loss of open sandbanks, changing food availability, increasing disturbance, and disease.Conservation implications: The fundamental character of the Wilderness Ramsar site has changed, with reduced abundance of several previously abundant herbivorous waterbirds. Drivers of change in species abundances are multifaceted, complex, and frequently poorly understood. Recommended local corrective actions include the management of emergent macrophytes, avian diseases, disturbance, and water quality.

Narsarsukite in peralkaline granites from the Papanduva Pluton, Graciosa Province, south Brazil: Insights from textural and compositional features

AbstractWe report textural and compositional data for the titanosilicate narsarsukite [Na2(Ti,Fe3+)Si4(O,F)11] in peralkaline granites from the Papanduva Pluton in Graciosa Province, south-southeastern Brazil. Two distinct narsarsukite generations, one late magmatic and the other post-magmatic, were identified on the basis of textural and compositional features. The magmatic generation consists of larger, euhedral to subhedral variably zoned crystals and late poikilitic intergrowths between narsarsukite and albite laths, representing the crystallisation of the latest melt pockets. The post-magmatic generation forms smaller, typically fibrous crystals and irregular aggregates that occur interstitially or replace the primary mafic minerals, particularly arfvedsonite. Compositions of narsarsukite from the Papanduva Pluton cover most of the compositional range described in known occurrences. The magmatic generation is enriched in Zr and depleted in Al. The Fe3+ and Al contents show a positive correlation for the magmatic crystals, but a negative correlation for the post-magmatic narsarsukite. The Al/Fe3+ ratios are higher in the post-magmatic crystals and can be used to discriminate between the two generations. The compositional variations are controlled mainly by the heterovalent substitution (Ti, Zr)4+ + O2– = (Al, Fe)3+ + F1–, and are compatible with (OH)1– ions in the O site. Narsarsukite has significantly higher concentrations of mid REE+Y and HFSE and very low to absent contents of LREE and LILE relative to the host-rocks. The average REE pattern of the magmatic crystals is highly fractionated, consistent with the expected strong preference for the smaller HREE. The post-magmatic crystals that replace arfvedsonite have flatter patterns, with higher concentrations of LREE and MREE. Their compositions suggest a fluid phase relatively rich in HFSE, REE, Y, Pb, Th and U. Narsarsukite is a common phase in strongly peralkaline granites such as the Papanduva Pluton and the well-known Strange Lake Complex, and should be considered a diagnostic mineral of highly peralkaline SiO2-oversaturated rocks containing rare Ti and Zr mineral assemblages.

Analysis of the dynamics and precipitation regime in the cross-border region Poland-Belarus- Ukraine (2010-2018)


 
 
 The work analyzes the dynamics and regime of atmospheric precipitation in the cross-border region of Poland-Belarus-Ukraine during the period 2010-2018. This time period was chosen, in particular, due to the need to find the prerequisites for the strong shallowing of lake complexes and the depletion of groundwater in the Polish region in 2019, which caused significant social and scientific resonance. The source data for the statistical part of the work were archival information from 17 weather stations in the specified region for this period. The main results of the study: 1) the dynamics of the average monthly precipitation amounts for each meteorological station were calculated and analyzed (Lutsk, Svityaz, Manevychi, Kovel, Liubeshiv, Volodymyr, Rivne, Dubno, Sarny, Brody, Rava-Ruska, Kamianka-Buzka, Pinsk, Pruzhany, Terespol, Wlodawa, Zamosc), the average amounts of precipitation that fell during the warm season of the year (IV-X months) and the cold season of the year (XI-III months), average annual precipitation amounts and precipitation amounts for the entire period, which was investigated (2010-2018). All calculated indicators were compared with the data of the climatic norm of 1961-1990). The annual number of days with precipitation, the warm and cold periods of the year, and the average values of this indicator were also determined. Based on the results of the statistical analysis, charts, cartograms, and several diagrams were developed that visually represent the peculiarities of the dynamics of atmospheric precipitation in the studied region during the analyzed period (2010-2018). 2) on the basis of the calculated indicators, maps of the geographical distribution of precipitation amounts on the territory of the cross-border region Poland-Belarus-Ukraine during the studied period (annual amounts, cold and warm season amounts) were constructed. When comparing them with maps of the period of the 20th century. Changes in the geography of distribution and trends of modern growth of precipitation amounts in the study region were revealed. After the analysis, a number of conclusions and generalizations were made: 1. During the period 2010-2018 in the territory of the cross-border region Poland-Belarus- Ukraine, the average annual amounts of precipitation increased by 20-45 mm compared to the climatic standard, while the average annual number of days with precipitation decreased by 25-30%. 2. Annual amounts of precipitation exceeded 600 mm at almost all (16 out of 17) meteorological stations whose data were analyzed. 3. The distribution of days with atmospheric precipitation during the seasons of the year has changed. The ratio between the amounts of precipitation that fell in the warm and cold periods of the year changed from 75/25 to 60/40 on average. In general, in the studied region, there are trends towards a slight increase in annual precipitation amounts, a redistribution of precipitation amounts in liquid and solid state in favor of rains, and a reduction in the total number of days with precipitation during the year and a more even distribution of them during the warm and cold seasons, compared to the climatic norm.
 
 

Effect of Land Use and Land Cover Change on Plant Diversity in the Ghodaghodi Lake Complex, Nepal

The Ghodaghodi Lake Complex is a Ramsar site, Nepal’s first bird sanctuary, and has significant ecological and economic values. The lake complex is in the western part of the lowland of the Terai region. Numerous studies indicate a relation between the normalized difference vegetation index (NDVI), land use, and land cover with plant diversity. However, the association between terrestrial plant diversity and NDVI in the Ghodaghodi Lake Complex is unknown but has important implications due to potential land use changes. We aimed to understand the relationship between plant diversity and NDVI in the Ghodaghodi Lake Complex. We performed a vegetation survey using a simple random sampling methodology. Shannon–Wiener’s diversity index (H’) was calculated from the field data, and Landsat images were used to compare land use and land cover changes and calculate NDVI values for 2000 and 2022. The image classification shows that forest cover in April and December 2000 was 71.1% and 58.5%, respectively, and was the dominant land cover in the study area. In contrast, agriculture occupied 18.8% and 27.3% in April and December 2000, respectively, and was the primary land use. Forests covered the most land in April (64.8%) and December (65.3%) of 2022. Likewise, agriculture was a widespread land use. We found a significant correlation (r = 0.80, p < 0.05) between the NDVI and plant species diversity, as the NDVI explained 65% of plant species diversity. There was a decrease in forest cover from 2000 to 2022. The strong correlation between the NDVI and vegetation species diversity shows that the NDVI can be a substitute for plant diversity. Our findings show that increased NDVI corresponds to increased plant species diversity and that the lake complex had more plant diversity in 2022 than in 2000, despite a decrease in forested lands.

Free and underfit-scavenger river dynamics dominate the large Amazonian Pacaya-Samiria wetland structure

The Peruvian Amazon is known for harboring the greatest biodiversity on the planet, with a world record for biodiversity per unit area. Previous studies suggested that the high ecological value depends on correlations between ecosystem functionality and seasonal inundation control vegetation patches. However, the knowledge on how river morphodynamics and its complex erosion-depositional processes influence the aquatic mosaic and fishing activity in the region is still incipient. This study examines the hydrogeomorphology of the Peruvian tropical wetland of Pacaya Samiria, located in Western Amazonia, and its role in the distribution of aquatic habitats. By using remote sensing techniques, the hydrogeomorphological connectivity that bounds the Pacaya Samiria National Reserve is characterized by ancient to modern river processes. Additionally, river signatures developed by the Ucayali, Marañon, Huallaga, Pacaya, and Samiria Rivers overlap with fish extraction and dominant vegetation to describe how geomorphology is associated with the spatial distribution of fishing zones. Results indicated that paleochannels regulate wetland drainage within the Ucamara Depression, supporting stational water stagnation, vegetation cover, and formation of carbon rich detritus, relevant aspects to understand fish traits. Moreover, the Ucayali River dominates river dynamics in the Pacaya Samiria wetland, thus playing a pivotal role in shaping the complexity of streams and lakes. Furthermore, underfit-scavenger meandering rivers are observed in areas where paleochannels from large rivers are found. A geomorphological characterization of drainage patterns in freshwater environments, such as Amazonian wetlands, is crucial to develop sound management strategies. This methodological approach is expected to support decision-making in conservation actions in Amazonian environments based on understanding wetland connectivity and hydrogeomorphological behavior and their influence on commercial fisheries.

Morphometric characteristics of the Krasnyj Klyuch lake Complex (Republic of Bashkortostan, Russia)

The article presents the results of researching the morphometric features of the Krasnyj Klyuch lake complex, located on the Ufa Plateau in the Republic of Bashkortostan on the left bank of the Ufa River. According to available data, the largest karst spring in Russia and the second in Europe in discharge of spring wells at the bottom of the lake complex, which makes the task of researching the morphometric characteristics of the lake complex itself an important step towards researching the unique spring. To date, detailed data, reflecting the features of the relief of the lake bottom have not been available. During the research, a bathymetric survey of the lake complex was carried out from the board of a boat, using an echo sounder, combined with a navigator. The results of field research were processed using the geoinformation program QGIS, a digital model of the relief of the lake basin was created and its main morphometric characteristics were calculated. The results of the researchhave both scientific significance, allowing to detail knowledge about the morphometric characteristics of the unique lake complex Krasnyj Klyuch, and applied – being the center of gravity of recreants, the lake complex Krasnyj Klyuch requires a detailed research of morphometric parameters in order to effectively organize recreation.

Pollution of Varna Lake and possibilities of using the pollutants as resources

Varna Lake is of great social and economic importance for the city of Varna and the entire region. The urbanisation of the areas surrounding the Varna-Beloslav Lake complex and the accelerated industrialisation around the coastline of Varna Bay have significant anthropogenic pressure on the aquatic ecosystem. An essential aspect is that industrial development, maritime transport and urbanisation are substantial sources of large-scale inorganic and organic pollution with all the resulting negative consequences. Recent measurements show that the surface sediments, which are a source of nutrients for the water body of Varna Lake, are contaminated with heavy metals and oil products. In this paper, we present a quantitative assessment of the degree of contamination with heavy metals (Hg, As, Fe, Cu, Pb) and petroleum products in the upper sediments of Varna Lake and then discuss opportunities for using some of these pollutants as a resource. The exploitation of these resources would bring significant benefits for improving the ecological status of Varna Lake.

Dynamics of environmental change and affecting factors in the Malili lake complex, South Sulawesi

The exploitation of the Malili Lake Complex in South Sulawesi as a natural resource that is not accompanied by wisdom has caused various major problems, such as damage to natural resources, loss of resources and the emergence of various wastes, which result in a decrease in the quality of the environment.The objectives of this research are: to examine in depth the dynamics of the quality of the aquatic environment and the influencing factors. Testing of environmental parameters measured in the field using a tool, namely the Water Quality Checker. Parameter measurements carried out in the field during June-August 2021 by taking six observation stations, namely: Salonsa Beach, Dream Beach, Malili River, Karebbe River, Sorowako Pier and Timampu Pier. The condition of the waters in has been polluted by the presence of domestic and industrial waste and the activities of the people who live in the vicinity.

Identification, genetic diversity, and comparative evolution of the striped snakehead Channa striata (Bloch, 1793) in Wallacea, Indonesia

Abstract. Irmawati, Meimulya, Tassakka ACMAR, Nadiarti, Rukminasari N, Kadriah IAK, Nasrullah H, Alimuddin. 2022. Identification, genetic diversity, and comparative evolution of the striped snakehead Channa striata (Bloch, 1793) in Wallacea, Indonesia. Biodiversitas 23: 3327-3337. Striped snakehead, Channa striata populations have declined in some areas of Wallacea. This study aimed to identify the species, analyze the genetic diversity, and trace the evolutionary relationships of snakeheads in the Wallacea region with snakeheads in other geographic areas. This study was identifying all specimens in this study as C. striata. The Wallacean C. striata sequences comprised three haplotypes with five polymorphic sites (single nucleotide polymorphisms, SNPs). No mutations were detected in the COI nucleotides of C. striata in the Tempe Lake complex, Patampanua River, and Bojo River; therefore, they belonged to the same haplotype. The C. striata from the Tangkoli tertiary drainage had unique haplotypes that differed from other C. striata haplotypes. The intraspecific genetic distance within C. striata was low while the interspecific genetic distance within the genus Channa was quite large, indicating that mutation rates are quite high in the genus Channa. Haplotype evolution showed that C. striata in Wallacea shared a common ancestral pathway with C. striata in Kalimantan, Java, and Bali and had a different ancestral pathway with C. striata in Lampung (Sumatra). The nucleotide composition of the C. striata COI gene followed the general pattern of the Teleostei and the Pisces superclass (T>C>A>G) with the G+C base percentage lower than the A+T percentage. The data from this study will be useful as a basis for designing germplasm conservation strategies and designing strategies to maintain C. striata populations and develop strains to meet future needs.

Estimating Suspended Sediment Fluxes from the Largest Glacial Lake in Svalbard to Fjord System Using Sentinel-2 Data: Trebrevatnet Case Study

Glacier-fed hydrological systems in high latitude regions experience high seasonal variation in meltwater runoff. The peak in runoff usually coincides with the highest air temperatures which drive meltwater production. This process is often accompanied by the release of sediments from within the glacier system that are transported and suspended in high concentrations as they reach the proglacial realm. Sediment-laden meltwater is later transported to the marine environment and is expressed on the surface of fjords and coastal waters as sediment plumes. Direct monitoring of these processes requires complex and time-intensive fieldwork, meaning studies of these processes are rare. This paper demonstrates the seasonal dynamics of the Trebrevatnet lake complex and evolution of suspended sediment in the lake and sediment plumes in the adjacent Ekmanfjorden. We use the Normalized Difference Suspended Sediment Index (NDSSI) derived from multi-temporal Sentinel-2 images for the period between 2016–2021. We propose a new SSL index combining the areal extent of the sediment plume with the NDSSI for quantification of the sediment influx to the marine environment. The largest observed sediment plume was recorded on 30 July 2018 and extended to more than 40 km2 and a SSL index of 10.4. We identified the greatest sediment concentrations in the lake in the beginning of August, whereas the highest activity of the sediment plumes is concentrated at the end of July. The temporal pattern of these processes stays relatively stable throughout all ablation seasons studied. Sediment plumes observed with the use of optical satellite remote sensing data may be used as a proxy for meltwater runoff from the glacier-fed Trebrevatnet system. We have shown that remote-sensing-derived suspended sediment indexes can (after proper in situ calibration) serve for large scale quantification of sediment flux to fjord and coastal environments.

Inventory of moraine-glacial lakes of the Shilik river basin and analysis of their spatial distribution

Nowadays Central Asia faces the challenge of addressing the challenges posed by climate change. Due to the increase in the temperature background, the active thermocarial processes lead to an annual increase in the number of moraine lakes and their areas. Insufficient information on the current state of the glacial and moraine lakes complex and their inventory and classification is one of the factors hindering the planning of the farm, the necessary construction work, disaster preparedness and risk assessment strategies and mitigation strategies. Detection and identification of moraine lakes in the Shilik River Basin was carried out on the basis of Google Earth module 9.x, remote sensing of the Earth and the use of GIS technology. The article identifies 143 lakes with a total area of ​​5.71 km2, located in the middle and high mountain zones of the Kungei and Ili Alatau ridges, based on the space imagery in recent years in the Shilik River basin. In addition, the data of remote sensing of the Earth allowed to determine the area of ​​the lake basins, their types and location features.

Historical analysis of an imperiled fish species: environmental variables modeling, biotic interactions, extirpation, and current restricted-range.

Analyses of spatial and temporal patterns and interactions are important for determining the abiotic factors limiting populations and the impact from other species and different anthropogenic stressors that promote the extirpation of species. The fish Hubbsina turneri de Buen (1940) was studied as a model species in a historical context at varying locations. Originally distributed only in the Lerma-Chapala basin, the main lake complex in Mexico, this species has not been collected from Lake Cuitzeo (LC) and now is restricted to Lake Zacapu (LZ). At present, the Highland splitfin is classified as critically endangered. Historical information of LC and historical and current information from LZ were explored by applying cluster analysis and generalized additive mixed model (GAMM) to describe the biotic interactions among fish species and the relationship between density and environmental variables, respectively. The two lakes' contrasting abiotic/biotic characteristics provided elements to describe some species distribution limits in chemical ion gradients. Extirpation calendar dates were estimated using an optimal linear estimation method. Finally, a bibliographic review was conducted on the causes that promoted the extirpation and restriction of H. turneri and the prognosis for its reestablishment and conservation. Clusters showed the fishes relationship according to their distribution along the lakes. GAMM indicated that high H. turneri density is related to low hardness/fecal coliforms, medium depth/suspended solids, and high oxygen concentration. Estimated extirpation dates were between the years 2013 and 2018. The extirpation was linked to an abrupt drop in the LC volume, water quality degradation, increased biotic interactions within macrophytes habitats with native and introduced species, and fisheries bycatches. The current restricted range of H. turneri resulted from the draining of the larger lake, forcing the remaining populations to small spring-fed remnants. Recent samplings in LZ resulted in a low number of individuals. The integration of ecological interactions derived from statistical models, extirpation dates from nonparametric tests, and the exhaustive analysis of historical information can be applied to define the current situation of imperiled, ecologically relevant species, in different aquatic ecosystems. We are confident that this general framework is important for determining (1) the requirements and limitations of populations regarding abiotic variables, (2) biotic interactions (trophic and spatial) with native and introduced species, and (3) different anthropogenic stressors within and around the ecosystem. This knowledge will also allow understanding those aspects that contribute to the extirpation of populations and could help the restoration of the habitat and the reintroduction of extirpated species.

Ridge-pool complexes of bogs in the middle taiga

Ridge-pool complex is typical for oligotrophic bogs of the middle taiga of Western Siberia. Vegetation monitoring shows that with a constant species composition of ecosystem vegetation, productivity (reserves of phytomass, mortmass and production) changes on average by 10-20 % due to weather conditions. In hot years, the production was 650-1100 g/m per year, while the reserves of live phytomass were 1200-2230 g/m, depending on the type of ecosystem. In cool and humid conditions, net primary production decreased to 660-830 g/m per year, while the stocks of live phytomass in different bog ecosystems were 1300-1600 g/m. On elevated relief elements in pine-shrub-sphagnum plant communities of ridges in hot years in the lake complex, the production reached a high value - 990 g/m per year. The more watered ecosystems of the basin of the lake complex remained the most productive (830 g/m per year). On lower relief elements in the ecosystems of hollows, the greatest contribution to the formation of total production is made by the underground organs of grasses, which make up more than 50-60 % of all production. The stocks of phytomass and net primary production in the hollows of these complexes are higher than in the hollows of the ridge-hollow complexes.