Search

Deep lakes are critical for freshwater storage, yet they are struggling against major ecological issues from climate change and nutrient pollution. A comprehensive understanding of internal feedback mechanisms is crucial for regulating nutrients in these lakes. A five‐year study was conducted on the diatom community and environment in Lake Fuxian, China's largest deep freshwater lake, which is becoming eutrophic. The results indicate a shift in the diatom community from a stable state dominated by a single species to a rapid seasonal fluctuation, and there is a significant increase in diatom biomass. Specifically, stable stratification and low nutrient concentrations are limiting the growth of diatom biomass and maintaining the dominance of Cyclotella. Nutrients in the hypolimnion were replenished in the epilimnion during the extreme cold of winter, triggering a shift in the diatom community. This shift may imply that future climate change will exacerbate the positive feedback of hypoxia‐nutrient release of algal blooms, potentially triggering a regime shift in the ecosystem of the entire lake. This study underscores the fact that climate change alters the internal feedback mechanisms of deep lakes, reducing ecosystem stability, and provides a scientific basis for further clarification of protection measures for deep lakes. [ABSTRACT FROM AUTHOR]

To investigate the in vitro digestive properties of fish oil with different proportions of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), based on an in vitro gastrointestinal digestion model (GIT), O/W fish oil emulsions with different ratios of EPA/DHA (5.13, 2.45, and 1.34) were prepared. The changes in the particle size, ζ-potential, and microstructure during digestion, as well as the release behavior of fatty acids during digestion in the small intestinal, were investigated. The results showed similar variation trends for fish oil emulsions with different EPA/DHA ratios. Despite this, each emulsion exhibited unique digestive characteristics. Specifically, all three initial emulsions showed higher stability, with strong negative charges, ranging from -40.02 to -43.77 mV, as well as relatively uniform particle size distributions (0.1-1.0 µm). After oral and gastric digestion, the absolute value of charge of each system decreased significantly (P<0.05), exposing the inner lipid phase. In addition, particle size was found to follow a multi-peak distribution and was mainly concentrated in the range of 10-100 µm. During small intestine digestion, the particle size of each system decreased significantly to 8-13 µm (P<0.05). The release of the free fatty acids (FFA) was 103.21% (EPA/DHA ratio of 5.13), 73.54% (EPA/DHA ratio of 2.45), and 62.51% ((EPA/DHA ratio of 1.34). These results suggest that the relative proportion of EPA and DHA is an important factor influencing fish oil emulsion digestion. This study provides a basis for the determination of the recommended daily EPA and DHA-rich marine lipid intake and the design of fish oil delivery systems. [ABSTRACT FROM AUTHOR]

For the lack of historical water ecology monitoring data and the limitations of traditional morphology-based water ecology reconstruction methods, the response mechanism of lake phytoplankton to climate change in the Tibetan Plateau remains unclear. In this study, we reconstructed the succession of phytoplankton community in Lake Gyaring, located in the northeastern Tibetan Plateau, since the 6th century by using sediment DNA metabarcoding. We found that the diversity and structure succession stages of phytoplankton community were consistent with the global temperature oscillation events, namely, the Medieval Warm Period (800–1300 CE). Little Ice Age (1300–1850 CE) and Current Warm Period (1850–2000 CE). The community structure dominated by Chlorophyta in the Medieval Warm Period gradually changed to that dominated by Bacillariophyta in the Little Ice Age. However, the Current Warm Period did not observe the dominant community structure of Chlorophyta similar to that of the Medieval Warm Period. This finding may be due to the climate change of the Current Warm Period was influenced by multiple human activities, such as increased anthropogenic aerosols, which promoted obvious weakening of the intensity of the summer monsoon, leading to decreased soil erosion and lake mixing, and thus may trigger a strikingly different aquatic ecosystem compared to that during the Medieval Warm Period. In this paper, the combination of genomics and palaeollimnology is helpful to explore the response mechanism of phytoplankton to climate change. [Display omitted] [ABSTRACT FROM AUTHOR]