Water

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20 pages, 2969 KiB

Open AccessArticle

Limnological Characteristics and Relationships with Primary Productivity in Two High Andean Hydroelectric Reservoirs in Ecuador

by Gonzalo Sotomayor, Andrés Alvarado, Jorge Romero, Carlos López, Marta Aguilar, Marie Anne Eurie Forio and Peter L. M. Goethals

Water 2024, 16(14), 2012; https://doi.org/10.3390/w16142012 - 16 Jul 2024

Viewed by 710

Abstract

Studies on limnology are essential to reservoir management; nevertheless, few are known about the limnological features of the Andean reservoirs in Ecuador. To overcome this limitation in the information, from December 2018 to December 2019, the limnological characteristics of El Labrado and Chanlud [...] Read more.

Studies on limnology are essential to reservoir management; nevertheless, few are known about the limnological features of the Andean reservoirs in Ecuador. To overcome this limitation in the information, from December 2018 to December 2019, the limnological characteristics of El Labrado and Chanlud reservoirs in the Machángara river basin (Ecuador south) were examined. Using the light/dark bottles technique, the primary productivity (PP) of phytoplankton was studied in conjunction with (1) vertical profiles of oxygen concentrations, water temperature, nitrogen, phosphorus, alkalinity, and heterotrophic bacteria; (2) Secchi disk transparency; and (3) meteorological factors such as wind force, precipitation, and water level. Data indicate that both reservoirs are polymictic, with alkaline waters, low nutrients, and low PP rates. Despite this, a principal component analysis revealed that Chanlud exhibits higher nitrogen, alkalinity, heterotrophic bacteria, and PP values. In two approaches through multiple linear regression analysis, each per reservoir, the PP was explained mainly by water temperature, depth, light, heterotrophic bacteria, and meteorological parameters. The low concentrations of nutrients and the low residency time explain the low PP values. Likewise, the altitudinal factor (i.e., both reservoirs are 3400 m above sea level) and the low human perturbations in surrounding reservoir zones play a crucial role in explaining their poor PP. Notwithstanding the low metabolic rates, clear seasonal trends were observed in both reservoirs; the lowest PP rates occurred during the cold season. To our knowledge, this is the first limnological study of high Andean reservoirs in Ecuador. These findings should be part of Andean reservoir management protocols, contributing significantly to local conservation efforts. Additionally, they could be extrapolated as a frame of reference to similar eco-hydrological systems. Full article

(This article belongs to the Special Issue Freshwater Ecosystems—Biodiversity and Protection)

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15 pages, 2929 KiB

Open AccessArticle

Study on the Spatiotemporal Distribution Characteristics of Meiofauna in Baiyangdian Lake and Its Influencing Factors

by Yingkun Cao, Jiandong Mu, Zhe Pan, Futang Ma, Jianxia Liu, Haojun Dong, Wei Zhang and Liqing Wang

Water 2024, 16(14), 1959; https://doi.org/10.3390/w16141959 - 11 Jul 2024

Viewed by 261

Abstract

Baiyangdian Lake, the largest freshwater shallow lake on the North China Plain, plays a pivotal role in maintaining the regional ecological balance and biodiversity. Meiofauna are integral components of Baiyangdian Lake; however, their community characteristics and relationship with environmental factors have not yet [...] Read more.

Baiyangdian Lake, the largest freshwater shallow lake on the North China Plain, plays a pivotal role in maintaining the regional ecological balance and biodiversity. Meiofauna are integral components of Baiyangdian Lake; however, their community characteristics and relationship with environmental factors have not yet been studied. The aim of the following study was to evaluate the density, spatiotemporal patterns, and habitat response dynamics of meiofauna in Baiyangdian Lake. A field investigation was conducted at 33 sites spanning various habitats, including aquatic plant-dominant, trench, and pelagic areas, across the spring, summer, and autumn seasons of 2021. The results revealed that the meiofauna in Baiyangdian Lake primarily comprise freshwater nematodes (91.78%), ostracods, and copepods, with a mean abundance of 69.40 ± 35.20 ind. 10 cm⁻², peaking in the spring, followed by summer and autumn. The mean biomass was 164.95 ± 99.39 dwt. 10 cm⁻², with that of ostracods being the most substantial and that of copepods being the least, with both of them exhibiting seasonal fluctuations. Notably, in the summer, the abundance of meiofauna was positively correlated with the water depth and negatively correlated with ammonia nitrogen levels (R² = 0.13 and R² = 0.24, respectively; p < 0.05 and p < 0.01; n = 33). The results of our study indicate that the distribution and abundance of meiofauna are significantly affected by environmental factors, with the water depth and ammonia nitrogen levels being potential key determinants. The results of the present study are conducive to evaluating the health status of the Baiyangdian ecosystem, protecting biodiversity, and studying the impacts of anthropogenic activities and environmental changes on the lake, and can also provide scientific support for its ecological restoration and governance as well as the assessment of ecological service functions. Full article

(This article belongs to the Special Issue Freshwater Ecosystems—Biodiversity and Protection)

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16 pages, 2477 KiB

Open AccessArticle

Tackling the Phylogeny of Lampreys—Insight from the Croatia’s Danube Basin

by Sara Pleše and Ivana Buj

Water 2024, 16(8), 1153; https://doi.org/10.3390/w16081153 - 19 Apr 2024

Viewed by 683

Abstract

This research addresses the pressing issue of protecting endangered lamprey species in Croatia, a crucial element in preserving biodiversity, particularly in the face of increasing human-induced impacts on natural ecosystems due to global warming. Lampreys, a group of vertebrates with an ancient lineage, [...] Read more.

This research addresses the pressing issue of protecting endangered lamprey species in Croatia, a crucial element in preserving biodiversity, particularly in the face of increasing human-induced impacts on natural ecosystems due to global warming. Lampreys, a group of vertebrates with an ancient lineage, are not fully understood taxonomically, posing a challenge to conservation efforts. In the Danube and Adriatic basins of Croatia, where lampreys are found, the lack of modern molecular methods and analyses has hindered an accurate determination of species numbers. This study aimed to bridge this knowledge gap by assessing the genetic diversity and structure of identified lamprey species and lineages in Croatia using the gene for cytochrome b. The research revealed four distinct lineages within the species Eudontomyzon vladykovi Oliva and Zanandrea, 1959 and confirmed the presence of the species Eudontomyzon danfordi Regan, 1911 in Croatia. Genetic diversity and differentiation tests, coupled with molecular diagnostic analyses, indicated moderate to high levels of genetic diversity within and between the identified species and lineages, emphasizing the deep structuring within Eudontomyzon vladykovi species. These results highlight the significance of understanding lamprey taxonomy and genetic diversity for effective conservation. The study provides important insights into the intricate relationships and conservation needs of lampreys, and provides a basis for future discussions involving additional genetic markers. By gaining a comprehensive understanding of the taxonomy, ecology, and genetic diversity of lampreys, we can ensure their conservation and that of associated ecosystems. Full article

(This article belongs to the Special Issue Freshwater Ecosystems—Biodiversity and Protection)

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14 pages, 2717 KiB

Open AccessArticle

Microplastics in the Danube River and Its Main Tributaries—Ingestion by Freshwater Macroinvertebrates

by Jelena Stanković, Djuradj Milošević, Momir Paunović, Boris Jovanović, Nataša Popović, Jelena Tomović, Ana Atanacković, Katarina Radulović, Davor Lončarević and Maja Raković

Water 2024, 16(7), 962; https://doi.org/10.3390/w16070962 - 27 Mar 2024

Cited by 1 | Viewed by 2789

Abstract

This study was carried out at the Danube River and its tributaries during the Joint Danube Survey 4 (JDS4) expedition. Three freshwater benthic species were used to estimate the quantity of microplastics (MPs): Corbicula spp., Limnodrilus hoffmeisteri (Claparede, 1862), and Polypedilum nubeculosum (Meigen, [...] Read more.

This study was carried out at the Danube River and its tributaries during the Joint Danube Survey 4 (JDS4) expedition. Three freshwater benthic species were used to estimate the quantity of microplastics (MPs): Corbicula spp., Limnodrilus hoffmeisteri (Claparede, 1862), and Polypedilum nubeculosum (Meigen, 1804). Following the kick and sweep technique, individuals were sampled using a hand net or dredge. In order to estimate the number of MP particles/individual particles/g wet body mass, the body mass and total length of all specimens were measured. Alkaline (Corbicula spp. and L. hoffmaisteri) and enzymatic (P. nubeculosum) protocols were performed for tissue degradation. All samples were filtered through glass microfiber filters (mesh size 0.5 µm). The particles were photographed, measured, and counted. A total of 1904, 169, and 204 MPs were isolated from Corbicula spp., L. hoffmaisteri, and P. nubeculosum, respectively. To confirm the chemical composition of isolated MPs, a subsample of 46 particles of the fragmented particles from 14 sampling sites was analysed via µ-ATR-FTIR spectroscopy analysis. The particles were characterised as polycarbonate (PC), polyethylene terephthalate (PET), polypropylene–polyethylene copolymer (PP-PE), nylon (polyamide-PA) and cellophane, with the domination of PET. Full article

(This article belongs to the Special Issue Freshwater Ecosystems—Biodiversity and Protection)

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17 pages, 5552 KiB

Open AccessArticle

Aquatic Insects (Ephemeroptera, Plecoptera and Trichoptera) Metric as an Important Tool in Water Quality Assessment in Hilly and Mountain Streams

by Bojana Tubić, Stefan Andjus, Katarina Zorić, Božica Vasiljević, Katarina Jovičić, Jelena Čanak Atlagić and Momir Paunović

Water 2024, 16(6), 849; https://doi.org/10.3390/w16060849 - 15 Mar 2024

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Abstract

The aim of the study was to test the significance of the EPT index in the water quality assessment of three types of water bodies in hilly and mountainous region of Serbia. The aquatic macroinvertebrate community was dominated by the group of insects, [...] Read more.

The aim of the study was to test the significance of the EPT index in the water quality assessment of three types of water bodies in hilly and mountainous region of Serbia. The aquatic macroinvertebrate community was dominated by the group of insects, of which 95 taxa represent the EPT group. We compared the obtained values of biological indices used for the assessment of water quality according to the national legislation with the overall status assessment represented by the ecological quality classes (EQC). The results of the Spearman correlation test showed a negative correlation of EQC with the EPT index, BMWP score, H′, total number of taxa and number of sensitive taxa, while a positive correlation was observed for the values of SI and Tubificinae %. The values of EQC and biological indices were subjected to principal component analysis (PCA). The results showed that the parameters that contributed most to the differences were the EPT index, the BMWP score and the number of sensitive taxa. The results indicate that the EPT index is an excellent indicator of changes in water quality and an important tool for the ecological categorization of water bodies in mountain regions. Full article

(This article belongs to the Special Issue Freshwater Ecosystems—Biodiversity and Protection)

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18 pages, 3780 KiB

Open AccessArticle

Distribution Range of the Endangered Species Unio crassus Philipsson, 1788 in Serbia (Western Balkans Region), Historical and Recent Data

by Jelena Tomović, Vladica Simić, Ana Petrović, Ana Atanacković, Katarina Zorić, Momir Paunović and Maja Raković

Water 2023, 15(24), 4248; https://doi.org/10.3390/w15244248 - 11 Dec 2023

Viewed by 1174

Abstract

The thick-shelled river mussel, Unio crassus Philipson, 1788, is considered to be one of the species with the highest conservation priority in Serbia. The study represents the first comprehensive research of the distribution of U. crassus in Serbian waters. The research covered [...] Read more.

The thick-shelled river mussel, Unio crassus Philipson, 1788, is considered to be one of the species with the highest conservation priority in Serbia. The study represents the first comprehensive research of the distribution of U. crassus in Serbian waters. The research covered a variety of waterbody types throughout Serbia, and distribution data were considered over three time periods from 1953 to 2019. The paper summarizes all the available literature data, field research and information obtained during the review of the collection of malacological material of the Natural History Museum in Belgrade. The results show a positive population trend, which is reflected in an extension of the distribution area and an increase in population density. After reviewing the museum collection, 13 synonyms for U. crassus were identified. The study also revealed a better insight into the habitat requirements and the limiting factors of the species. Substrate characteristics, waterbody types, altitude, and nitrate content of the water seem to be of great importance for the occurrence of the species. The results presented here can improve further measures for the conservation of U. crassus, not only in Serbia, but also in the Western Balkans. Full article

(This article belongs to the Special Issue Freshwater Ecosystems—Biodiversity and Protection)

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12 pages, 7475 KiB

Open AccessArticle

Effects of Environmental Factors on the Distribution and Diversity of Aquatic Oligochaetes

by Ana Atanacković, Nataša Popović, Nikola Marinković, Jelena Tomović, Jelena Đuknić, Jelena Stanković and Momir Paunović

Water 2023, 15(22), 3873; https://doi.org/10.3390/w15223873 - 7 Nov 2023

Cited by 1 | Viewed by 1229

Abstract

The aim of our study was to detect the actual distribution of oligochaete species and to identify their ecological differentiation with respect to environmental factors: altitude, temperature, oxygen concentration, conductivity, total organic carbon, and waterbody type. Although widespread, differentiation of oligochaete communities in [...] Read more.

The aim of our study was to detect the actual distribution of oligochaete species and to identify their ecological differentiation with respect to environmental factors: altitude, temperature, oxygen concentration, conductivity, total organic carbon, and waterbody type. Although widespread, differentiation of oligochaete communities in four waterbody types and altitudinal groups can be observed through alpha and beta diversity. Their differences were analyzed using MANOVA, while the ecological preferences of species were presented with logistic Gaussian regression analyses. The highest number of the species of Oligochaeta was recorded in oligochaete communities in medium and large rivers. Total beta diversity decreased with the decreasing of waterbody size, the increasing of size of the substrate particles, river flow velocity, as well as altitude. Communities from small mountain rivers and streams and large and medium rivers with coarser substrate differed from other oligochaete communities. When coarser substrate was prevalent in smaller and medium rivers, a domination of a certain family was observed: Lumbriculidae (>800 m a.s.l.), Propappidae and Enchytraeidae (500–800 m), and Naididae (<500 m a.s.l.). Common species of Oligochaeta, with significantly overlapping ranges in running waters in Serbia, still show a clear grouping with respect to preference for certain types of waterbodies. Full article

(This article belongs to the Special Issue Freshwater Ecosystems—Biodiversity and Protection)

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20 pages, 3719 KiB

Open AccessFeature PaperArticle

Phytoplankton Diversity of a Natural Karst Lake Combining Morphological and Molecular Approaches

by Maja Šimunović, Antonija Kulaš, Petar Žutinić and Marija Gligora Udovič

Water 2023, 15(7), 1379; https://doi.org/10.3390/w15071379 - 3 Apr 2023

Cited by 1 | Viewed by 1990

Abstract

Phytoplankton are considered to be one of the most sensitive indicators of the ecological status of lakes. Nowadays, it is essential to recognize the prospects of the molecular approach (eDNA metabarcoding) in phytoplankton community assessments and combine them with the existing traditional microscopy-based [...] Read more.

Phytoplankton are considered to be one of the most sensitive indicators of the ecological status of lakes. Nowadays, it is essential to recognize the prospects of the molecular approach (eDNA metabarcoding) in phytoplankton community assessments and combine them with the existing traditional microscopy-based morphological approach before its standardization. In this study, the aim was to characterize the phytoplankton community of a natural karstic lake by combining and comparing the morphological and molecular approach to check the applicability of eDNA metabarcoding as a biomonitoring tool. A total of 51 phytoplankton taxa were found using the morphological approach, whilst the molecular approach discovered 97 ASVs that corresponded to the algal community. The comparability of both approaches in describing phytoplankton communities is evident in the designation of centric diatoms, dinoflagellates and cryptophytes as descriptive taxa. Furthermore, both approaches proved reliable in detecting functional groups (Lo, C, X2, X3) with similar ecological demands. Moreover, the results have shown that euphotic zone samples can be reliably exchanged by composite samples to provide an accurate characterization of phytoplankton communities in the euphotic zone. It was confirmed that eDNA metabarcoding is an applicable tool for biodiversity monitoring of a natural karst lake and should be used as a feasible supplement to traditional microscopy in the phytoplankton community assessments, with regards to the drawbacks of each method. Full article

(This article belongs to the Special Issue Freshwater Ecosystems—Biodiversity and Protection)

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