Search Results (21)

Gehu Lake in the lower reaches of the Taihu Lake Basin has experienced water quality degradation due to increasing human activities, pollutant discharge, and non-point source pollution, which requires ecosystem restoration. Currently, the community structure of aquatic organisms and their influencing environmental factors remain poorly understood. Thus, in this study, we conducted comprehensive fieldwork in June 2024 and analyzed the community structures of plankton (i.e., phytoplankton and zooplankton) and macroinvertebrates, and their influencing environmental factors in Gehu Lake and the inflowing river. The trophic level index (TLI) and biodiversity indices (Shannon–Wiener, Pielou, and Margalef) were utilized to assess water quality status. Pearson correlation analysis and redundancy analysis (RDA) were applied to identify key factors influencing plankton and macroinvertebrate community structures. The dominant phytoplankton species included Merismopedia tranquilla, Microcystis aeruginosa, Aphanizomenon flos-aquae, Aphanocapsa elachista, and Aulacoseira granulata. The dominant zooplankton species were mainly Brachionus diversicornis, Brachionus calyciflorus, and Asplanchna priodonta. The dominant macroinvertebrate species were Microchironomus tabarui and Chironomus flaviplumus. The findings suggest that Gehu Lake exhibited moderate pollution levels, while the diversity indices were significantly correlated with environmental factors. The Shannon–Wiener index of zooplankton displayed a markedly negative correlation with Chl-a (p < 0.05). The results from redundancy analysis showed that TP, TN, SD, COD_Mn, and Chl-a were key environmental factors shaping the aquatic community structure in the lake. Full article

Sympatric distribution and temporal overlap of cryptic zooplankton species pose a challenge to the framework of the niche differentiation theory and the mechanisms allowing competitor coexistence. We applied the methods of phylogenetic analysis, DNA taxonomy, and statistical analysis to study the temporal distribution patterns of the cryptic B. calyciflorus species, an excellent model, in three lakes, and to explore the putative mechanisms for their seasonal succession and temporal overlap. The results showed that in the warm-temperate Lake Yunlong, B. fernandoi and B. calyciflorus s.s. underwent a seasonal succession, which was largely attributed to their differential adaptation to water temperature. In the subtropical Lake Jinghu, B. fernandoi, B. calyciflorus s.s., and B. dorcas exhibited both seasonal succession and temporal overlap. Seasonal successions were largely attributed to their differential adaptation to temperature, and temporal overlap resulted from their differential responses to algal food concentration. In the tropical Lake Jinniu, B. calyciflorus s.s. persisted throughout the year and overlapped with B. dorcas for 5 months. The temporal overlap resulted from their differential responses to copepod predation. These results indicated that the temporal distribution pattern of the cryptic B. calyciforus species and the mechanism that allows competitor coexistence vary with different climate zones. Full article

Micro(nano)plastics (MNPs) can be generated from a variety of sources, including the breakdown of larger plastic items, the abrasion of synthetic textiles, and the fragmentation of plastic waste. These particles can become airborne and be transported by wind, potentially leading to their presence in the atmosphere. Due to their widespread applications, ZnO particles at the nanometer range have attractive proprieties that make them appropriate for being combined with polymers, especially PET (polyethylene terephthalate), the most commonly used polymer in the packaging sector. Nevertheless, ZnO NPs have a potential ecotoxicity that could be reflected in PET-ZnO composites reaching the environment in the form of micro(nano)plastics. To assess the potential release of PET-ZnO, as well as the ecotoxicity of ZnO NPs, PET-ZnO and weathered composites were analyzed. The ecotoxicity of PET-ZnO was tested in organisms representing different food-chain levels and compared to ZnO NPs’ ecotoxicity. The composite form contained a stable dispersion of around 3.7% of NPs uniformly scattered in the polymeric matrix. ZnO NPs were toxic to Vibrio fischeri and Brachionus calyciflorus. PET-ZnO did not exhibited any toxicity to the organisms studied, while a moderate level of toxicity was observed for the weathered forms. Full article

As the primary consumers in aquatic organisms, zooplankton play an important role in aquatic ecosystems. It is valuable for management and researchers to have an insight into the responses of zooplankton community patterns to environmental factors. In this study, RDA and variation partitioning analysis were adopted to determine the important environmental factors affecting zooplankton abundance and biomass, as well as the relative importance of different environmental factors. The findings reveal that TN (total nitrogen), WD (water depth), pH, and SAL (salinity) were all important abiotic factors shaping the zooplankton community pattern in the study area. TN affected protozoa by influencing Stentor amethystinus, while the effects of WD on copepods may have been mainly induced by the responses of Calanus sinicus and Paracyclopina nana. By inhibiting Stentor amethystinus and Vorticella lutea, pH significantly affected protozoa. In addition, Rotifera and copepods were affected by SAL mainly through the responses of Brachionus calyciflorus, Calanus sinicus, and Ectocyclops phaleratus. Importantly, fundamental alternations in the variation trends of zooplankton abundance and biomass along the salinity gradient were found when the salinity was approximately 4–5. By combining these results with the findings on phytoplankton responses to salinity in previous studies, it can be concluded that salinity may influence the river ecosystem by influencing zooplankton abundance and biomass rather than phytoplankton. Full article

The construction and use of navigation and irrigation canals are among the common human alterations in landscapes and ecosystems. The North Crimean Canal (NCC) is the longest in Europe; its main branch is 403 km, and the total of all its branches exceeds 10,000 km. It is a main driver of the significant environmental changes in an all-arid part of Crimea. No zooplankton studies in the canal have been carried out up to this time at all. In 2022, zooplankton was studied in different sites from May to October. Total zooplankton abundance fluctuated between 170 and 19,560 ind. m⁻³, and wet biomass between 0.75 and 1057 mg m⁻³. In total, 11 Rotifera species, 11 Cladocera species, and 15 Copepoda species, including 2 Harpacticoida, 5 Calanoida, and 8 Cyclopoida, were found in plankton. The most common Rotifera species were Brachionus calyciflorus, Euchlanis dilatate, and Keratella cochlearis. Among Cladocera, Chydorus sphaericus, Bosmina longirostris, and Coronatella rectangular have the highest frequency of occurrence. In Copepoda, these were Acanthocyclops vernalis, Eurytemora affinis, and Nitocra typica. Among the 37 species found in NCC, 10 were not previously noted in the water bodies of Crimea. Among rotifers, they were Ploesoma hudsoni, Polyarthra dolichoptera, Pompholyx complanata, Synchaeta grandis, and Synchaeta stylata. Bosminopsis zernowi, Rhynchotalona rostrata, and Scapholeberis mucronata were not noted before among Cladocera. Eurytemora lacustris and Cyclops smirnovi were first found in Crimea among Copepoda. New technogenic aquatic ecosystems such as NCC are the “gateway” for the invasion of alien species into the new regions. Full article

First feeding of many fish larvae depends on live feed. A comparative investigation on the effectiveness of different types of live feed is not available to our knowledge. Hence, we conducted a study to examine the effect of different types and combinations of live feed on the performance (survival rate, total length, body width, body mass, malformation rate) of pikeperch, Sander lucioperca, larvae. From day 0 (onset of exogenous feeding) to day 10, the saltwater rotifer Brachionus plicatilis, the freshwater rotifer Brachionus calyciflorus, the ciliate Paramecium bursaria, copepods (nauplii and copepodites) from a lake population, and Artemia nauplii were tested. Feeding with B. plicatilis, B. calyciflorus, and P. bursaria resulted in high survival rates of 80% and a homogenous and significant growth (increase in total length of 50% and in body width of 20%). As follow-up feed, copepod nauplii and Artemia nauplii were tested from day 11 to day 20. Copepod nauplii were superior to Artemia nauplii, as larvae fed with copepods showed higher survival rates (67–70% versus 38–47%) and a more homogeneous growth. A switch from seawater live feed to freshwater live feed or vice versa resulted in decreased survival rates. Therefore, a feeding regime consisting of B. calyciflorus or P. bursaria followed by copepods is considered optimal as first feed of pikeperch. The malformation rate was not affected by the tested feeding regimes. To investigate the wider applicability and transferability of these findings, complementary investigations were performed on burbot, Lota lota, and the freshwater whitefish Coregonus atterensis. The feeding regimes used for S. lucioperca larvae were also suitable for Lota lota. Moreover, L. lota could be fed with lake copepods from the onset of exogenous feeding. For C. atterensis, initial feeding with B. plicatilis, B. calyciflorus, or P. bursaria had no positive effects. Feeding with copepods from the onset of exogenous feeding was optimal considering survival rate and growth. Therefore, optimal first feeding regimes are very species specific and should be established for each new species. Full article

The development of new formulations can be driven by the knowledge of host–guest complexes using cyclodextrins which have the ability to include guest molecules within their hydrophobic cavities, improving the physicochemical properties of the guest. To rationally explore new pesticide formulations, the effects of cyclodextrins on the properties of such guest molecules need to be explored. Imidacloprid is a neonicotinoid systemic insecticide used worldwide. In this study, the inclusion complexes of Imidacloprid (IMI) with β-cyclodextrin (β-CD) were prepared in the solid state by co-precipitation and the physical mixing method, with a stoichiometry of 1:1 and 1:2 molar ratios. The obtained products, Imidacloprid:β-cyclodextrin inclusion complex (IMI:β-CD), were characterized in the solid state by Fourier transform-infrared (FT-IR) spectroscopy and X-ray powder diffractometry (XRD). In solution, the 1:1 stoichiometry for the inclusion complexes was established by the Job plot method, and the binding constant of IMI:β-CD was determined by UV–vis titration. The toxicity was determined in producers and primary consumers of the freshwater trophic chain, the green alga Raphidocelis subcapitata and the rotifer Brachionus calyciflorus, respectively. The results indicated that Imidacloprid forms inclusion complexes with CDs showing improved physicochemical properties compared to free Imidacloprid. The formation of the inclusion complex reduced the chronic toxicity in rotifers when IMI concentrations were close to those of environmental concern (tenths/hundredths of micromoles/L). Therefore, CD inclusion complexes could provide important advantages to be considered for the future industrial production of new formulations. Full article

Global warming and environmental pollution have created a unique combination of abiotic and biotic stresses to zooplankton. However, little information is available on the effects of antipsychotic drugs commonly used to treat psychosis, such as chlorpromazine (CPZ), on non-target aquatic organisms in light of global warming. This study investigated how dopamine concentrations (DAC), acute toxicity and chronic toxicity of Brachionus calyciflorus changed in response to CPZ and gradually increasing temperatures. The results showed that the concentration range of rotifer DAC was 1.06~2.51 ng/g. At 18, 25 and 32 °C, the 24 h LC₅₀ was 1.795, 1.242 and 0.833 mg/L, respectively. Compared to the control, exposure to CPZ significantly decreased life expectancy at hatching, the net reproduction rate, generation time, population growth rate and dopamine concentration of B. calyciflorus in all three temperatures (p < 0.05). The toxicity of CPZ to rotifers was increased by high temperature. These findings indicated that CPZ is highly toxic to rotifers, displaying high ecological risks to aquatic ecosystems. Full article

Zooplankton bodies are organic-rich micro-environments that support fast bacterial growth. Therefore, the abundance of zooplankton-associated bacteria is much higher than that of free-living bacteria, which has profound effects on the nutrient cycling of freshwater ecosystems. However, a detailed analysis of associated bacteria is still less known, especially the relationship between those bacteria and bacterioplankton. In this study, we analyzed the relationships between Brachionus calyciflorus-associated bacterial and bacterioplankton communities in freshwater using high-throughput sequencing. The results indicated that there were significant differences between the two bacterial communities, with only 29.47% sharing OTUs. The alpha diversity of the bacterioplankton community was significantly higher than that of B. calyciflorus-associated bacteria. PCoA analysis showed that the bacterioplankton community gathered deeply, while the B. calyciflorus-associated bacterial community was far away from the whole bacterioplankton community, and the distribution was relatively discrete. CCA analysis suggested that many environmental factors (T, DO, pH, TP, PO₄^3-, NH₄⁺, and NO₃^-) regulated the community composition of B. calyciflorus-associated bacteria, but the explanatory degree of variability was only 37.80%. High-throughput sequencing revealed that Raoultella and Delftia in Proteobacteria were the dominant genus in the B. calyciflorus-associated bacterial community, and closely related to the biodegradation function. Moreover, several abundant bacterial members participating in carbon and nitrogen cycles were found in the associated bacterial community by network analysis. Predictive results from FAPROTAX showed that the predominant biogeochemical cycle functions of the B. calyciflorus-associated bacterial community were plastic degradation, chemoheterotrophy, and aerobic chemoheterotrophy. Overall, our study expands the current understanding of zooplankton–bacteria interaction and promotes the combination of two different research fields. Full article

The prevalence of hexavalent chromium [Cr(VI)] and microplastics (MPs) is ubiquitous and is considered a threat to aquatic biota. MPs can act as a vector for waterborne metals; however, the combined effects of Cr(VI) and MPs on aquatic organisms are largely unknown. In this study, aquatic model animals, such as rotifers (Brachionus calyciflorus and B. plicatilis), water fleas (Daphnia magna), amphipods (Hyalella azteca), polychaetes (Perinereis aibuhitensis), and zebrafish (Danio rerio) were exposed to environmental concentrations (1, 10, and 100 particles L⁻¹) of 1 μm polystyrene MPs alone, Cr(VI) alone, or Cr(VI) combined with MPs. Following exposure, the potential effects were measured by analyzing basic life endpoints (e.g., survival rate and growth). A significant response to MPs alone was not observed in all animals. However, MPs combined with Cr(VI) concentration-dependently increased Cr(VI) toxicity in two rotifer species. The survival rate of water fleas was significantly reduced upon exposure to Cr(VI) + MPs (100 particles L⁻¹) compared with exposure to Cr(VI) alone, and significantly decreased the number of offspring. Although there was no significant effect on the body length of the amphipod, concentration-dependent decreases in their survival rates were observed. In contrast, no significant change was found in the survival rate of polychaetes; however, their burrowing ability was inhibited by Cr(VI) + MPs (100 particles L⁻¹). Further, larval mortality was increased in response to Cr(VI) + MPs (100 particles L⁻¹) in zebrafish. Taken together, the findings suggest that MPs can exacerbate Cr(VI) toxicity, even at environmental levels. Full article

As an intermediary connection between primary producers and higher trophic levels, zooplankton are an important component of the aquatic food chain, contributing significantly to aquatic biological productivity. This study describes the zooplankton diversity and community structure, as well as their relationships with ecological factors, in homestead ponds of a coastal district along the northern Bay of Bengal region. Significant differences (p < 0.05) were detected in the mean values of temperature, pH, DO, TDS, transparency, and phosphates from the ponds during December 2020, but no significant differences were found in the nitrate levels. However, no significant variances in the ecological parameters between months were found due to the study taking place in the same season. Sixteen zooplankton species, representing four groups, were found in the study area, with the highest mean abundance of 301.19 ± 40.55 ind./L recorded in February 2021 and the lowest of 293.02 ± 21.13 ind./L recorded in December 2020. The diversity (H’), evenness (e), richness (J), and dominance (D) ranged from 2.49 to 2.12, from 0.93 to 0.84, from 2.05 to 1.56, and from 0.13 to 0.09, respectively. Based on the SIMPER analysis, Diaptomus gracilis and Brachionus calyciflorus were found to be significant contributors (>10%) to the zooplankton community structure in different months. The ANOSIM results revealed that 10 species of zooplankton were significant contributors based on their average dissimilarity. The canonical correspondence analysis (CCA) identified that pH, transparency, nitrates, and phosphates have a significant impact on the abundance of zooplankton species in the homestead ponds in the study area. Full article

Predation is a strong species interaction causing severe harm or death to prey. Thus, prey species have evolved various defence strategies to minimize predation risk, which may be immediate (e.g., a change in behaviour) or transgenerational (morphological defence structures). We studied the behaviour of two strains of a rotiferan prey (Brachionus calyciflorus) that differ in their ability to develop morphological defences in response to their predator Asplanchna brightwellii. Using video analysis, we tested: (a) if two strains differ in their response to predator presence and predator cues when both are undefended; (b) whether defended individuals respond to live predators or their cues; and (c) if the morphological defence (large spines) per se has an effect on the swimming behaviour. We found a clear increase in swimming speed for both undefended strains in predator presence. However, the defended specimens responded neither to the predator presence nor to their cues, showing that they behave indifferently to their predator when they are defended. We did not detect an effect of the spines on the swimming behaviour. Our study demonstrates a complex plastic behaviour of the prey, not only in the presence of their predator, but also with respect to their defence status. Full article

A new cultivation system with the chlorophyte Monoraphidium contortum combined with a self-sustaining culture of the freshwater rotifer Brachionus calyciflorus was applied for Sander lucioperca (L.) larviculture. Survival, morphometrics, as well as fatty acid composition of pikeperch larvae were analyzed after a ten-day feeding period. By using the pseudo-green water technique with improved aeration and water movement at the surface, survival rates reached up to 94%, with a total larval length of 8.1 ± 0.3 mm and a specific length growth rate of up to 4.1% day⁻¹ for S. lucioperca. The biochemical composition of B. calyciflorus and especially its contents in C18 PUFAs and suitable n-3/n-6 ratios met the nutritional requirements of pikeperch larvae. The high abundance of highly unsaturated fatty acids (HUFAs) in the diet appeared to be less important in the first feeding due to a possible retention of essential fatty acids, which originate from the yolk sac reserves, at adequate levels. Exponential growth of microalgae and zooplankton under the applied conditions was most effective when stocking M. contortum five days and B. calyciflorus three days before adding the fish larvae. Appropriate timing and sufficient live feed density allowed a successful integration of B. calyciflorus into pikeperch larviculture. We hypothesize that feeding pikeperch larvae with a self-sustaining Brachionus-culture under pseudo-green water conditions with minor disruptions during larviculture will improve survival and growth. This system is a first step towards pikeperch larviculture inside recirculated aquaculture systems (RAS) under continuous feed supply with live feed within the same aquaculture unit. Full article

Due to their high biodiversity and adaptation to a mutable and challenging environment, aquatic lophotrochozoan animals are regarded as a virtually unlimited source of bioactive molecules. Among these, lectins, i.e., proteins with remarkable carbohydrate-recognition properties involved in immunity, reproduction, self/nonself recognition and several other biological processes, are particularly attractive targets for biotechnological research. To date, lectin research in the Lophotrochozoa has been restricted to the most widespread phyla, which are the usual targets of comparative immunology studies, such as Mollusca and Annelida. Here we provide the first overview of the repertoire of the secretory lectin-like molecules encoded by the genomes of six target rotifer species: Brachionus calyciflorus, Brachionus plicatilis, Proales similis (class Monogononta), Adineta ricciae, Didymodactylos carnosus and Rotaria sordida (class Bdelloidea). Overall, while rotifer secretory lectins display a high molecular diversity and belong to nine different structural classes, their total number is significantly lower than for other groups of lophotrochozoans, with no evidence of lineage-specific expansion events. Considering the high evolutionary divergence between rotifers and the other major sister phyla, their widespread distribution in aquatic environments and the ease of their collection and rearing in laboratory conditions, these organisms may represent interesting targets for glycobiological studies, which may allow the identification of novel carbohydrate-binding proteins with peculiar biological properties. Full article

Plastic pollution is an increasing environmental problem, but a comprehensive understanding of its effect in the environment is still missing. The wide variety of size, shape, and polymer composition of plastics impedes an adequate risk assessment. We investigated the effect of differently sized polystyrene beads (1-, 3-, 6-µm; PS) and polyamide fragments (5–25 µm, PA) and non-plastics items such as silica beads (3-µm, SiO₂) on the population growth, reproduction (egg ratio), and survival of two common aquatic micro invertebrates: the rotifer species Brachionus calyciflorus and Brachionus fernandoi. The MPs were combined with food quantity, limiting and saturating food concentration, and with food of different quality. We found variable fitness responses with a significant effect of 3-µm PS on the population growth rate in both rotifer species with respect to food quantity. An interaction between the food quality and the MPs treatments was found in the reproduction of B. calyciflorus. PA and SiO₂ beads had no effect on fitness response. This study provides further evidence of the indirect effect of MPs in planktonic rotifers and the importance of testing different environmental conditions that could influence the effect of MPs. Full article