Freshwater Ponds Research Articles

Taxonomic relationship does not limit dietary assemblages in fish: an investigation in small freshwater fishes

Abstract Foraging profitability is one of the significant factors affecting habitat selection in fishes. The food habits of the fish species vary seasonally due to the dynamic nature of their environment. For that, the dietary analysis of a fish is essential in the case of fish diversity research. Most of the variations in prey size consumed by piscivores were correlated to the differences in piscivore body size, which morphological constraints can explain. The present study aimed to investigate the ecomorphological assemblage of small indigenous freshwater fish species from smaller lentic freshwater bodies based on a range of morphological traits and evaluate fish assemblages with respect to the feeding guilds. Freshwater ponds around Birbhum district, West Bengal (India) were selected for the collection of fish species, namely Amblypharyngodon mola, Puntius sophore, Esomus danrica, Lepidocephalichthys guntea, Chanda nama, Parambassis lala, Trichogaster fasciata, Anabas testudineus and Glossogobius giuris. Morphometric and gut content analysis were done, and the trophic guild matrix, taxonomic distance matrix, and morphological matrix were calculated. The result showed a strong association between ecomorphological traits and trophic structure, indicating an independent assemblage pattern beyond the taxonomic influence.

Methane Emissions From the Qinghai‐Tibet Plateau Ponds and Lakes: Roles of Ice Thaw and Vegetation Zone

AbstractComprehensive seasonal observation is essential for accurately quantifying methane (CH4) emissions from ponds and lakes in permafrost regions. Although CH4 emissions during ice thaw are important and highly variable in high‐latitude freshwater ponds and lakes (north of ∼50°N), their contribution is seldom included in estimates of aquatic‐atmospheric CH4 exchange across different alpine ecosystems. Here, we characterized annual CH4 emissions, including emissions during ice thaw, from ponds and lakes across four alpine vegetation zones in the Qinghai‐Tibet Plateau (QTP) permafrost region. We observed significant spatial variability in annual CH4 emission rates (8.44−421.05 mmol m−2 yr−1), CH4 emission rates during ice thaw (0.26−144.39 mmol m−2 yr−1), and the contribution of CH4 emissions during ice thaw to annual emissions (3−33%) across different vegetation zones. Dissolved oxygen concentration under ice, along with substrate availability and water salinity, played critical roles in influencing CH4 flux during ice thaw. We estimated annual CH4 emissions from ponds and lakes in the QTP permafrost region as 0.04 (0.03−0.05) Tg CH4 yr−1 (median (first quartile−third quartile)), with approximately 20% occurring during ice thaw. Notably, the average areal CH4 emission rate from ponds and lakes in the QTP permafrost region amounts to only 8% of that from high‐latitude waterbodies, primarily due to the dominance of large saline lakes with lower CH4 emission rates in the alpine permafrost region. Our findings emphasize the significance of incorporating comprehensive seasonal observation of CH4 emissions across different vegetation zones in better predicting CH4 emissions from alpine ponds and lakes.

The possibilities of using of captive and domestic broodstocks for saving of natural populations: 1. Acipenseriformes (part 1)

In last years the stocks of Russian species of sturgeons decreased to critical level which can be followed by their complete extinction in nature. As a result, the number of sturgeons beginning spawning migration into rivers are extremely small, but Astrakhan sturgeon hatcheries continue release annually about 35 mln fry using own broodstocks of two types — captive and domestic ones. However the releases of offspring of domestic broodstock are extremely discussible. On one hand, creation of such broodstocks could avoid the complete extinction of natural populations of Adriatic sturgeon Acipenser naccari in Po River and European sturgeon A. sturio in Gironde estuary. On other hand, long-term practice of commercial fish farming had shown that even the accidental refugees from sea cages or fresh-water ponds caused great harm to natural populations of same species. Hatchery individuals were undergoing different selection than fish in wild nature and had poorly formed reflexes (searching for food and avoiding predators). Besides a progressive decrease in genetic diversity with each generation could be seen in such fry due to limited number of parents (the Ryman-Laikre effect). However the creation of captive and domestic broodstocks of endangerous species and subspecies (Azov beluga Huso huso maeotica, fringebarbel sturgeon Acipenser nudiventris, Sakhalin sturgeon Acipenser mikadoi) and extinct populations (Baltic sturgeon Acipenser oxyrinchus) remains the only way to release hatchery juveniles. The first part of presented review is devoted to creation and using of captive and domestic broodstocks for conservation-type sturgeon fry releases in Russia and other countries.

The possibilities of using of captive and domestic broodstocks for saving of natural populations: 1. Acipenseriformes (part 2)

In last years the stocks of Russian species of sturgeons decreased to critical level which can be followed by their complete extinction in nature. As a result, the number of sturgeons beginning spawning migration into rivers are extremely small, but Astrakhan sturgeon hatcheries continue release annually about 35 mln fry using own broodstocks of two types — captive and domestic ones. However the releases of offspring of domestic broodstock are extremely discussible. On one hand, creation of such broodstocks could avoid the complete extinction of natural populations of Adriatic sturgeon Acipenser naccari in Po River and European sturgeon A.sturio in Gironde estuary. On other hand, long-term practice of commercial fish farming had shown that even the accidental refugees from sea cages or fresh-water ponds caused great harm to natural populations of same species. Hatchery individuals were undergoing different selection than fish in wild nature and had poorly formed reflexes (searching for food and avoiding predators). Besides a progressive decrease in genetic diversity with each generation could be seen in such fry due to limited number of parents (the Ryman-Laikre effect). However the creation of captive and domestic broodstocks of endangerous species and subspecies (Azov beluga Huso huso maeotica, fringebarbel sturgeon Acipenser nudiventris, Sakhalin sturgeon Acipenser mikadoi) and extinct populations (Baltic sturgeon Acipenser oxyrinchus) remains the only way to release hatchery juveniles. The first part of presented review is devoted to creation and using of captive and domestic broodstocks for conservation-type sturgeon fry releases in Russia and other countries.

Satellite imagery as a management tool for monitoring water clarity across freshwater ponds on Cape Cod, Massachusetts

Water clarity serves as both an indicator and a regulator of biological function in aquatic systems. Large-scale, consistent water clarity monitoring is needed for informed decision-making. Inland freshwater ponds and lakes across Cape Cod, a 100-km peninsula in Massachusetts, are of particular interest for water clarity monitoring. Secchi disk depth (SDD), a common measure of water clarity, has been measured intermittently for over 200 Cape Cod ponds since 2001. Field-measured SDD data were used to estimate SDD from satellite data, leveraging the NASA/USGS Landsat Program and Copernicus Sentinel-2 mission, spanning 1984 to 2022. Random forest machine learning models were generated to estimate SDD from satellite reflectance data and maximum pond depth. Spearman rank correlations (rs) were “strong” for Landsat 5 and 7 (rs = 0.78 and 0.79), and “very strong” for Landsat 8, 9, and Sentinel-2 (rs = 0.83, 0.86, and 0.80). Mean absolute error also indicated strong predictive capacity, ranging from 0.65 to 1.05 m, while average bias ranged from −0.20 to 0.06 m. Long- and recent short-term changes in satellite-estimated SDD were assessed for 193 ponds, selected based on surface area and the availability of maximum pond depth data. Long-term changes between 1984 and 2022 established a retrospective baseline using the Mann-Kendall test for trend and Theil-Sen slope. Generally, long-term water clarity improved across the Cape; 149 ponds indicated increasing water clarity, and 8 indicated deteriorating water clarity. Recent short-term changes between 2021 and 2022 identified ponds that may benefit from targeted management efforts using the Mann-Whitney U test. Between 2021 and 2022, 96 ponds indicated deteriorations in water clarity, and no ponds improved in water clarity. While the 193 ponds analyzed here constitute only one quarter of Cape Cod ponds, they represent 85% of its freshwater surface area, providing the most spatially and temporally comprehensive assessment of Cape Cod ponds to date. Efforts are focused on Cape Cod, but can be applied to other areas given the availability of local field data. This study defines a framework for monitoring and assessing change in satellite-estimated SDD, which is important for both local and regional management and resource prioritization.

Revision of Lower Devonian clam shrimp (Branchiopoda, Diplostraca) from the Rhenish Massif (Eifel, SW-Germany), and the early colonization of non-marine palaeoenvironments

Three collections of clam shrimp from the Lower Devonian (upper lower Emsian) Klerf Formation of Willwerath and Waxweiler in the western Eifel Mountains are herein studied. Four discernible morphotypes are present in the Willwerath assemblage. These morphotypes correspond to the previously described species from this locality: Pseudestheria diensti (Gross), Pseudestheria subcircularis Raymond, and Palaeolimnadiopsis? eifelensis Raymond. The fourth morphotype also closely corresponds to Pseudestheria diensti, but is slightly different in outline. Asmussia willweratica (Novozhilov) is an objective synonym of Pseudestheria subcircularis. In the Willwerath clam shrimp sample, it is difficult to disentangle taphonomic/preservational versus ontogenetic/sexual variation. If taphonomic/preservational causes could be confirmed, all the Willwerath specimens may represent just one taxon and Pseudestheria subcircularis and Palaeolimnadiopsis? eifelensis would be potential subjective synonyms of Pseudestheria diensti. However, we refrain from a formal taxonomic act, which requires a larger number of specimens to be analysed.In addition, we investigated two samples from Waxweiler, which originate from distinct centimetre-thick layers and therefore represent associations. One of these associations comprises two discernible clam shrimp morphotypes. Because of limited preservation of morphological characters, one is here left in open nomenclature as Spinicaudata incertae sedis, whereas the other is recognised as a new species of the family Palaeolimnadiopseidae, Palaeolimnadiopsis frankeorum sp. nov. The second association from Waxweiler comprises at least four, possibly six different clam shrimp taxa. In addition to Pseudestheria diensti, Palaeolimnadiopsis sp., and poorly preserved Asmussia- and Ulugkemia-like specimens, two taxa can be described as new, namely the vertexiid Cornia wasvilrensis sp. nov. and the leaiine Eicheleaia wenndorfi gen. nov. et sp. nov. Altogether, the Klerf Formation at Waxweiler yields a total of at least five (possibly eight) clam shrimp taxa. The palaeoenvironment of these early clam shrimp from the Klerf Formation is interpreted as a non-marine, relatively proximal deltaic setting with no or very minor marine influence, such as a deltaic freshwater pond or lake. The comparatively high diversity of these lower Devonian clam shrimp suggests a considerably earlier origin and cryptic evolution of the group.

A Review on Freshwater Pond Fish Farming in Cambodia

A Review on Freshwater Pond Fish Farming in Cambodia

Algal communities in urban freshwater ponds: prospects for biodiesel production

Algal communities in urban freshwater ponds: prospects for biodiesel production

Fictibacillus fluitans sp. nov., isolated from freshwater pond.

A Gram-positive, aerobic, rod-shaped, spore-forming bacterium, designated NE201T, was isolated from a freshwater pond in Village Nerur, India. Growth was observed in the range of 15-45°C temperature with optimum at 30°C, pH range of 5-9 (optimum at 7.0), and at concentrations of NaCl ranging between 0 and 14% (optimum 0%, w/v). The 16S rRNA gene sequence showed the highest similarity with Fictibacillus enclensis NIO-1003T (JF893461) at 99.01% followed by F. rigui WPCB074T (EU939689) at 98.9% and F. solisalsi CGMCC 1.6854T (EU046268) at 98.66%. The digital DNA-DNA hybridization (dDDH) and orthoANI values for strain NE201T against F. enclensis NIO-1003T (GCA_900094955.1) were 33.7% and 87.68%, respectively. The phylogenetic analysis based on the 16S rRNA gene, 92 core genes derived from the genome, and 20 proteins involving over 20,236 amino acid positions revealed the distinct phylogenetic position of strain NE201T and the formation of a clearly defined monophyletic clade with F. enclensis. The strain NE201T showed a unique carbon utilization and assimilation pattern that differentiated it from F. enclensis NIO-1003T. The major fatty acids were anteiso -C15:0 (51.42%) and iso-C15:0 (18.88%). The major polar lipids were phosphatidylglycerol (PG), phosphatidylethanolamine (PE, and diphosphatidylglycerol (DPG). The antiSMASH analyzed genome of NE201T highlighted its diverse biosynthetic potential, unveiling regions associated with terpene, non-ribosomal peptide synthetases (NRPS), lassopeptides, NI-siderophores, lanthipeptides (LAP), and Type 3 Polyketide Synthases (T3PKS). The overall phenotypic, genotypic, and chemotaxonomic characters strongly suggested that the strain NE201T represents a novel species of genus Fictibacillus for which the name Fictibacillus fluitans sp. nov. is proposed. The type strain is NE201T(= MCC 5285 = JCM 36474).

Understanding the differential impacts of two antidepressants on locomotion of freshwater snails (Lymnaea stagnalis)

There is growing evidence of negative impacts of antidepressants on behavior of aquatic non-target organisms. Accurate environmental risk assessment requires an understanding of whether antidepressants with similar modes of action have consistent negative impacts. Here, we tested the effect of acute exposure to two antidepressants, fluoxetine and venlafaxine (0–50 µg/L), on the behavior of non-target organism, i.e., freshwater pond snail, Lymnaea stagnalis. As compounds interact with chemical cues in the aquatic ecosystems, we also tested whether the effects altered in the presence of bile extract containing 5α-cyprinol sulfate (5α-CPS), a characterized kairomone of a natural predator, common carp (Cyprinus carpio). Behavior was studied using automated tracking and analysis of various locomotion parameters of L. stagnalis. Our results suggest that there are differences in the effects on locomotion upon exposure to venlafaxine and fluoxetine. We found strong evidence for a non-monotonic dose response on venlafaxine exposure, whereas fluoxetine only showed weak evidence of altered locomotion for a specific concentration. Combined exposure to compounds and 5α-CPS reduced the intensity of effects observed in the absence of 5α-CPS, possibly due to reduced bioavailability of the compounds. The results highlight the need for acknowledging different mechanisms of action among antidepressants while investigating their environmental risks. In addition, our results underline the importance of reporting non-significant effects and acknowledging individual variation in behavior for environmental risk assessment.Graphical

Hardware Realization of Long Range (LoRa) Based Telemetry System for Aquaculture Monitoring

Freshwater fish farming must pay attention to the condition of the water content in the pond and the water quality in the pond. Fish will feel comfortable if the efficiency of oxygen levels and pond water content is maintained. Freshwater fish farming needs to optimize crop yields so as not to get losses. The problem that is often encountered is that many fish die in the pond due to lack of water. Irrigation channels leading to fishponds experience blockages. The smoothness of the irrigation channel affects the volume of water in the pond. Blockage of irrigation channels is usually due to garbage trapped in irrigation, causing dirty water to settle and water sequestration to occur in the pond. This tool system aims to improve water quality and increase the efficiency of oxygen levels by using TDS and ultrasonic sensors. The parameter value on the sensor affects the work of the tool actuator. The tool actuator is a water pump that is used as a substitute for irrigation channels and an aerator motor to increase dissolved oxygen in water by moving the propeller on the surface of the pond water. Wireless technology is used for data communication. Because the land of freshwater fish farming ponds is a large area and is far from settlements, wireless communication is suitable for enabling easy and fast access to information and services. In this research, the testing methods used are functional testing and system performance testing. Functional testing is used to prove whether the system that has been implemented can meet the requirements of operational functions as planned. System performance testing is intended to monitor several parameters that can show the ability and reliability of the system in carrying out its operational functions. The result of the overall test is the LoRa communication distance that can communicate up to about 1000 meters, proving that LoRa technology has a strong enough ability in terms of range wireless communication. The PLE (Path Loss Exponent) of the LoRa module with 100 meters in LoS (indoor) conditions is 7.77, while in nLoS conditions in obstructed in-building, it is 10.13. The average error of the ultrasonic sensor type JSN SR-04T is 0.16% and has a difference of ± 1 cm. The TDS sensor with dissolved pool water content has an average value of 142.6 ppm with an error value of 1.05%. The PDAM water content has an average value of 112.1 ppm with a sensor value of 1.38%. The water content of the lime and detergent mixture has the highest observed ppm value, which is an average of 737.33 ppm, with a sensor error of 0.14%. The water pump activates when the pool water is low (when the ultrasonic distance reaches 60 cm), and the aerator activates when the water content is contaminated (when the TDS sensor value exceeds 500 ppm).

Water–Salt Migration Patterns among Cropland–Wasteland–Fishponds in the River-Loop Irrigation Area

In order to investigate the influence of freshwater fish ponds on water and salt transport in cultivated wasteland in salinized areas, a typical study area was selected in the middle and lower reaches of the Hetao Irrigation District in China in the Yichang Irrigation Domain, and the temporal and spatial changes in the salinity of soil and salinity of groundwater and fish pond water in the cultivated–wasteland–fish pond system were characterized through the monitoring of the environmental information of soil and groundwater at the boundaries of the cultivated land, wasteland, and fish ponds. Salinity changes and groundwater migration in different periods were determined, and the response of soil salinity to the depth of groundwater burial was analyzed, as well as the effect of fish ponds on soil salinization. The results showed that the amount of groundwater migrating from cropland to wasteland during the simulation period in 2022 was 2700 m3, the amount of groundwater migrating from wasteland to fish ponds was 630 m3, and the amount of groundwater migrating from fish ponds to wasteland during the fall watering period was 440 m3. From an overall perspective, the average soil salinity of wasteland was 1.56 times higher than that of the boundary of fish ponds. Not only do fish ponds play a positive role in the ecosystem, but they also have a desalinization effect that reduces soil salinity significantly. Groundwater depth and soil salinity have an exponential relationship; when the depth of groundwater is greater than 1.75 m, the soil salinity varies little with the depth of groundwater and the soil salinity is less than 0.66 ds/m, which can be determined as the critical depth, and the average depth of groundwater in cultivated land in the study area is 1.5 m. Therefore, it is necessary to reasonably control the water level of fish ponds, so as to make the groundwater depth of cultivated land control between 1.75 m and 2.0 m, and to prevent soil salinization.

Effect of feed enriched with fermented coconut water products on growth and carcass composition of gurami sago (Osphronemus goramy Lacepède, 1801) juvenile.

Background Giant gourami (Osphronemus goramy Lacepede, 1801) is a popular freshwater species in Indonesia, but there is limited information on feed used for its cultivation. Therefore, this study aims to determine effect of feed enriched with fermented coconut water and palm sap sugar solution on growth, feed efficiency, and carcass composition of juvenile sago gurami. Methods A total of 2 litres coconut water and 1litres palm sap sugar solution (10%) were formulated. Each formulated product was then mixed with 6 g Aspergillus niger (P1), 6 g Rhizopus oligosporus (P2), and 6 g Saccharomyces cerevisiae (P3) to obtain the supplements. Subsequently, supplementation was carried out on commercial feed at a dose of 300 ml/kg of feed. Samples supplemented with P1, P2, and P3 were designated P1, P2, and P3 diets, while feed added to freshwater was considered P4 (placebo). Gurami sago juvenile (initial weight 50±2.5 g and length 13.2±0.4 cm) were then placed in triplicate nets (2×1×1 m) in a freshwater concrete pond with a stocking density of 30 fish/net. Results The different products formulations had a significant effect (p<0.05) on growth performance. The weight gain in P1, P2, P3, and P4 diets were 167.24%, 193.99%, 134,22%, and 115.98%, respectively. For feed conversion efficiency, the values obtained were 0.65, 0.73, 0.65, and 0.64 in P1, P2, P3, and P4, respectively. Furthermore, supplementing commercial feed with varying products formulation had a significant impact (p<0.05) on the fatty acid composition and carcass body of gurami sago. Lipid content in fish carcass fed P1, P2, P3, and P4 were 2.90%, 4.42%, 2.98%, and 2.76%, respectively. Conclusion Based on the results, P2 contained a higher concentration of fatty acids compared to other diets, leading to increased body weight, feed efficiency, and carcass fatty acid composition in sago gurami reared in freshwater concrete ponds.

Characterization of Some Physico-Chemical Parameters of Water Bodies Inhabited by Small Indigenous Fish Species (SIFs): A Case Study

The physico-chemical properties of water bodies play crucial role in determining the life history as well as assemblage of inhabitant fish. The aim of this study was to analyse some water and sediment content parameters of inhabitant water bodies and investigate if there persists any correlation between physico-chemical parameters and fish assemblage. Freshwater ponds around Birbhum district, West Bengal (India) were selected for collection of water, sediment, and fish species samples. Temperature (°C), dissolved oxygen (DO), pH, nitrogen and phosphorous contents of water and sediment were analysed. Fish ecomorphological indices were calculated. The range of variations of the physico-chemical parameters in pond water were measured. For identifying the factors determining species assemblage, interaction effects of the factors throughout the seasons were first analysed. The analysis results of N and P contents from water and sediment showed no significant seasonal difference and correlation with assemblage. Next, fish species wise correlation of ecomorphological indices to temperature (T), dissolved oxygen (DO), total dissolved solid (TDS) and pH was analysed. Correlation analysis showed that temperature and pH had a moderate to strong correlation with most of the ecomorphological indices that determines the behaviour of SIFs as depicted by the indices. These two parameters could be considered as major direct parameters to understand the distribution of SIFs in water bodies.

Review of Central-Eastern European Propagation and Larvae Nursing Method for Common Carp (Cyprinus carpio L.).

Common carp (Cyprinus carpio L.) as a cultivated fish species has huge importance all over the world. According to FAO statistics, carp is the third most widely bred freshwater pond fish species; only two other Cyprinids (silver carp and grass carp) are bred in higher amounts. Carp is native all over Asia and in a large part of Europe. As a result of human intervention, at present, carp are widespread all over the world, except for the Arctic region. Carp breeding was launched in the antique period, in the ancient Chinese Empire and the Roman Empire. The presently applied method of breeding of common carp has a long evolution. From the effectiveness point of view, the propagation and early-life nursing are crucial parts of carp production, as they provide seed stocks for the further growing section. Without effective propagation, there is no intensive carp production. Nowadays, more advanced propagation methods are available all over the world; however, in the current review, only the main milestones and production efficiency of the propagation and nursing method used in the ponds of Eastern Central Europe are discussed. In the historical overview of carp reproduction, first the natural reproduction, then the semi-extensive and intensive hatchery propagation are presented and investigated in detail. The analysis focuses on the advantages and disadvantages of the method. In particular, the different important milestones of the advanced hatchery method are shown and explained. The effectiveness is proven even with practical calculations. Not only the reproduction, but the pond nursing method is also presented and discussed, concentrating on the management of evolutionarily adapted natural feeds (Zooplankton) and their effect on the survival of fish larvae.

Fire transforms effects of terrestrial subsidies on aquatic ecosystem structure and function.

Fire can lead to transitions between forest and grassland ecosystems and trigger positive feedbacks to climate warming by releasing CO2 into the atmosphere. Climate change is projected to increase the prevalence and severity of wildfires. However, fire effects on the fate and impact of terrestrial organic matter (i.e., terrestrial subsidies) in aquatic ecosystems are unclear. Here, we performed a gradient design experiment in freshwater pond mesocosms adding 15 different amounts of burned or unburned plant detritus and tracking the chronology of detritus effects at 10, 31, 59, and 89 days. We show terrestrial subsidies had time- and mass-dependent, non-linear impacts on ecosystem function that influenced dissolved organic carbon (DOC), ecosystem metabolism (net primary production and respiration), greenhouse gas concentrations (carbon dioxide [CO2 ], methane [CH4 ]), and trophic transfer. These impacts were shifted by fire treatment. Burning increased the elemental concentration of detritus (increasing %N, %P, %K), with cascading effects on ecosystem function. Mesocosms receiving burned detritus had lower [DOC] and [CO2 ] and higher dissolved oxygen (DO) through Day 59. Fire magnified the effects of plant detritus on aquatic ecosystem metabolism by stimulating photosynthesis and respiration at intermediate detritus-loading through Day 89. The effect of loading on DO was similar for burned and unburned treatments (Day 10); however, burned-detritus in the highest loading treatments led to sustained hypoxia (through Day 31), and long-term destabilization of ecosystem metabolism through Day 89. In addition, fire affected trophic transfer by increasing autochthonous nitrogen source utilization and reducing the incorporation of 15 N-labeled detritus into plankton biomass, thereby reducing the flux of terrestrial subsidies to higher trophic levels. Our results indicate fire chemically transforms plant detritus and alters the role of aquatic ecosystems in processing and storing carbon. Wildfire may therefore induce shifts in ecosystem functions that cross the boundary between aquatic and terrestrial habitats.

Life after a fiery death: Fire and plant biomass loading affect dissolved organic matter in experimental ponds.

Drier and hotter conditions linked with anthropogenic climate change can increase wildfire frequency and severity, influencing terrestrial and aquatic carbon cycles at broad spatial and temporal scales. The impacts of wildfire are complex and dependent on several factors that may increase terrestrial deposition and the influx of dissolved organic matter (DOM) from plants into nearby aquatic systems, resulting in the darkening of water color. We tested the effects of plant biomass quantity and its interaction with fire (burned vs. unburned plant biomass) on dissolved organic carbon (DOC) concentration and degradation (biological vs. photochemical) and DOM composition in 400 L freshwater ponds using a gradient experimental design. DOC concentration increased nonlinearly with plant biomass loading in both treatments, with overall higher concentrations (>56 mg/L) in the unburned treatment shortly after plant addition. We also observed nonlinear trends in fluorescence and UV-visibleabsorbance spectroscopic indices as a function of fire treatment and plant biomass, such as greater humification and specific UV absorbance at 254 nm (a proxy for aromatic DOM) over time. DOM humification occurred gradually over time with less humification in the burned treatment compared to the unburned treatment. Both burned and unburned biomass released noncolored, low molecular weight carbon compounds that were rapidly consumed by microbes. DOC decomposition exhibited a unimodal relationship with plant biomass, with microbes contributing more to DOC loss than photodegradation at intermediate biomass levels (100-300 g). Our findings demonstrate that the quantity of plant biomass leads to nonlinear responses in the dynamics and composition of DOM in experimental ponds that are altered by fire, indicating how disturbances interactively affect DOM processing and its role in aquatic environments.

Аналіз лінійно-вагових показників річкових раків (Astacus) у водоймах Дніпропетровської області

This research focuses on studying the narrow-clawed crayfish in the Dnipropetrovsk region. The narrow-clawed crayfish, Astacus leptodactylus, is a crucial component of industrial fisheries and plays a significant role in the development of aquatic ecosystems. Within the territory of the Dnipropetrovsk region, crayfish inhabit various freshwater bodies, including rivers, lakes, floodplains, and ponds. It is known that water bodies in the Dnipro region undergo substantial anthropogenic impact, leading to alterations in the life cycles and reproductive features of hydrobionts. Investigated areas of reservoirs were characterized by diverse levels and factors of pollution, such as contamination of water with chemical and radioactive substances, oil products, wastewater, and the use of nitrogen and phosphorus fertilizers. These anthropogenic interventions may result in a decrease in populations of aquatic organisms, posing a serious threat to water ecosystems. The sensitivity to environmental changes makes crayfish a valuable bioindicator species. Fertility indicators and morphometric characteristics can be considered as bioindicators. The analysis of linear-weight parameters revealed that crayfish extracted from the Zaporizhzhia Reservoir had a body length 15–18% greater than those from the Kamianske and Samara Bay. Additionally, they exhibited larger cephalothorax dimensions by 18–20%, and their mass was almost 50% higher compared to individuals from other water bodies. Samara Bay demonstrated significantly lower fertility indicators compared to the Zaporizhzhia Reservoir, with crayfish fertility being reliably 63% lower. The established differences in morphometric indicators between crayfish from the Zaporizhzhia Reservoir, Samara Bay and Kamianske Reservoir may indicate heterogeneity in the living conditions within the water bodies of Dnipropetrovsk and might be induced by anthropogenic pressures.

The limits of stress-tolerance for zooplankton resting stages in freshwater ponds.

In seasonal environments, many organisms evolve strategies such as diapause to survive stressful periods. Understanding the link between habitat stability and diapause strategy can help predict a population's survival in a changing world. Indeed, resting stages may be an important way freshwater organisms can survive periods of drought or freezing, and as the frequency and extent of drought or freezing vary strongly among habitats and are predicted to change with climate change, it raises questions about how organisms cope with, and survive, environmental stress. Using Daphnia magna as a model system, we tested the ability of resting stages from different populations to cope with stress during diapause. The combination of elevated temperatures and wet conditions during diapause shows to prevent hatching altogether. In contrast, hatching is relatively higher after a dry and warm diapause, but declines with rising temperatures, while time to hatch increases. Resting stages produced by populations from summer-dry habitats perform slightly, but consistently, better at higher temperatures and dryness, supporting the local adaptation hypothesis. A higher trehalose content in resting eggs from summer-dry habitat might explain such pattern. Considering that temperatures and summer droughts are projected to increase in upcoming years, it is fundamental to know how resting stages resist stressful conditions so as to predict and protect the ecological functioning of freshwater ecosystems.

Pengaruh Pemberian Pakan Terhadap Pertumbuhan Dan Perkembangan Ikan Mas (Cypriynus carpio)

Goldfish (Cyprinus carpio) is a type of food fish which is a freshwater fishery commodity that has good prospects. Goldfish (Cyprinus carpio) are animals that live in temperate climates and live in freshwater ponds. The aim of this research is to determine the effect of providing these 3 feeds and to determine the development and growth of goldfish after being treated with these three feeds. The method used in this research is an experimental method by providing treatment with the three feeds. Based on the research results, it was found that the growth and development of goldfish can be influenced by several things, including: age, size, density and space for movement. Each type of fish food has a certain daily growth rate value which depends on water quality.