Flood events can significantly affect the physical and biological processes of aquatic ecosystems in a short time, leading to rapid changes in phytoplankton community structure. The Huayanghe Lakes experienced extreme flooding in the summer of 2020, with the water level reaching 16.42 m. In order to understand the effects of flooding on phytoplankton diversity and community structure, eight samples were collected in the Huayanghe Lakes from 2019 to 2020. Water-level disturbance has a significant influence on lake-water quality and phytoplankton community structure. The results showed that the Secchi depth increased from 65.36 to 8.52 cm, while the concentration of total nitrogen (from 0.98 to 0.7 mg/L) and total phosphorus (from 0.04 to 0.031 g/L) decreased. In addition, flooding significantly increased the Shannon–Wiener diversity index, the Pielou index, and the Margalef richness index by an average of 43.5%, 36.7%, and 40.21%, respectively. The phytoplankton community structure in the Huayanghe Lakes changed due to the change of physicochemical environment caused by flood. While in the pre-flood period phytoplankton was composed of large diatoms (e.g., Aulacoseira granulata), cyanobacteria (e.g., Microcystis sp., Anabaena sp., and Aphanizomenon sp.) and other multicellular taxa, the flood period showed an increase in the proportion of chlorophytes and diatoms that quickly adapted to settle in new environments. Pearson correlations and redundancy analyses showed that water level fluctuation was the most significant environmental factor affecting the phytoplankton community between the regular hydrological cycle and flood periods. There are few studies on phytoplankton in the Huayanghe Lakes, and the present study provides basic data on phytoplankton diversity and community structure. In addition, it provides a theoretical basis for controlling water level change in the Yangtze River.

Potential changes in phytoplankton community structure in shallow lakes due to land use could pose a serious threat to ecosystem sustainability and functioning. Nevertheless, this effect has not been analyzed in detail. In this study, we chose two adjacent lakes, the main land use types around them are farmland and forest, respectively. We investigated the spatial differences in the phytoplankton community structure, water quality physicochemical parameters, and land use patterns in the two lakes. The results indicated that the annual average cell density and biomass of phytoplankton in the former were 1.84 times and 2.38 times that of the latter, respectively. The results of Pearson correlation and Redundancy analysis showed that total nitrogen (TN), total phosphorus (TP), water depth (WD), and water temperature (WT) were the main environmental factors influencing the structural changes of phytoplankton communities in the two lakes. The results indicated that different land use patterns, such as farmland and towns around the lake, increase the nitrogen (N) and phosphorus (P) content of the lake, while the forests distributed around the lake can reduce the N and P entering the lake, which is probably the main reason for the spatial difference in the characteristics of phytoplankton communities in the two lakes. Our results highlight that land use significantly affects the community structure of phytoplankton by influencing physicochemical factors in water bodies. Our study can provide guidance for pollution control and water quality management of shallow lakes.

Extreme climate events caused by global climate change pose a huge threat to freshwater ecosystems. As the frequency and intensity of heatwaves increase, sustained heatwaves may increase their certainty in ecosystems, which may affect phytoplankton and zooplankton, the key components of freshwater ecosystems. Sustained heatwaves can lead to shifts in plankton community structure, driven by changes in immigration patterns and life history strategies, potentially resulting in altered functional characteristics of phytoplankton and zooplankton in aquatic ecosystems. However, research on the effects of sustained heatwaves on plankton has mostly been conducted in laboratories, with less data from studies in natural water bodies. Therefore, in order to understand this ecological process in natural lakes, this study investigated the phytoplankton and zooplankton in Shengjin Lake during the summer heatwave in 2022. The results show that sustained heatwaves significantly alter the composition of plankton communities: Cyanophyta dominated during the heatwave period, while Bacillariophyta replaced Cyanophyta as the dominant group during the heatwave acclimation period. For zooplankton, the community shifted from being dominated by Rotifera to being dominated by Cladocera and Copepoda. Water temperature is a key driving factor affecting plankton communities, with contribution rates of 33.83% and 38.70% to the changes in zooplankton and phytoplankton communities, respectively. The connectivity of plankton co‐occurrence networks and keystone species change dynamically with heatwaves. Sustained heatwaves can exert thermal selective pressure on plankton communities, favoring the survival of individuals or species with stronger high‐temperature tolerance and potentially inducing acclimation or other adaptive responses. These results provide data support for studying the impact of sustained heatwaves on plankton communities and also provide a new perspective for the management and protection of freshwater ecosystems under climate change.

The degradation and loss of natural wetlands has caused severe crises for wetland taxa. Meanwhile, constructed wetlands are expanding significantly and facing dramatic environmental changes. Exploring the responses of wetland organisms, particularly zooplankton, may have important implications for the management of wetlands. Environmental and zooplankton samples were collected from 34 subsidence wetlands created by underground coal mining across the North China Plain in August 2021. We used generalized linear models and redundancy analysis to test zooplankton responses to environmental variables, with the relative importance quantified by variation partitioning. We identified 91 species, divided into 7 functional groups, with the highest density of rotifer filter feeders (RF, 2243.4 ± 499.4 ind./L). Zooplankton species richness was negatively correlated with electrical conductivity (EC), chlorophyll-a, total phosphorus, and pH. The Shannon–Weiner and Pielou evenness indices were positively correlated with transparency and negatively correlated with the photovoltaic panel area (AS). Rotifer predators (RCs) and RF densities were positively correlated with cropland area and dissolved oxygen, but negatively correlated with AS. Small crustacean filter feeders positively correlated with AS, whereas medium crustacean feeders (MCFs) positively correlated with EC. AS was the most critical variable affecting the zooplankton community. Our study showed that the spatial pattern of zooplankton communities was shaped by environmental heterogeneity across the subsidence wetlands, providing implications for the management and conservation of these constructed wetlands.

Global climate change is intensifying extreme weather events such as floods and heatwaves, posing serious threats to lake ecosystems. The Huayanghe Lakes experienced a catastrophic flood in 2020 and a prolonged heatwave in 2022, providing an opportunity to compare zooplankton responses to contrasting extreme climate events. Based on summer water quality and zooplankton data collected from the Huayanghe Lakes during 2020–2023, this study used 2021 and 2023 as reference years to examine the summer zooplankton community state during the post-event period following extreme climate events. In 2020, 43 species belonging to 14 families and 25 genera were recorded, dominated by rotifers such as Polyarthra euryptera and Trichocerca spp., with a mean density of 239.26 ind./L. In contrast, 34 species from 12 families and 21 genera were identified in 2022, with dominant taxa including Diurella rousseoeti, Trichocerca cylindrica and Thermocyclops hyalinus, resulting in a lower mean density of 149.17 ind./L. Zooplankton density and species richness were higher during flood conditions but declined under prolonged heatwave conditions. Mantel correlation analysis identified water transparency as the primary environmental factor shaping zooplankton communities. Overall, zooplankton responded more strongly to flooding than to sustained heatwaves, indicating that different extreme climate events amplify the regulatory roles of distinct environmental drivers.

Constructing microbial fuel cells (MFCs) with conductive polypyrrole (PPy) as the anode is a promising strategy for simultaneous wastewater treatment and energy recovery. However, achieving both high loading of electrogenic microorganisms for the generation of electrons and high conductivity for efficient electron transfer is generally difficult for PPy-based anodes, which limits their practical application. We first constructed a bioanode through in situ-synthesized Fe²⁺-doped zeolitic imidazolate framework-67 (ZIF-67) on PPy (ZIF-67/Fe-PPy). ZIF-67/Fe-PPy increased the conductivity of the bioanode with a charge transfer resistance (R_ct) of 36 Ω, lower than that of the PPy anode (75 Ω), which might have been due to the extended conjugated structures formed by pyrrole monomers and the redox cycle of Fe²⁺–Fe³⁺. Moreover, the redox cycle of Fe²⁺–Fe³⁺ during the treatment of wastewater benefited the enrichment of electrogenic Geobacter species, thereby significantly enhancing the stability and power generation efficiency of the MFC. Besides the high conductivity, the in situ-synthesized ZIF-67/Fe-PPy microporous structure expanded the initial adsorption and biofilm growth surface area. This phenomenon led to a final microbial biomass density of 66.7 mg cm⁻² on ZIF-67/Fe-PPy, which was significantly greater than that of the CF electrode (20.9 mg cm⁻²), and the PPy electrode (40.5 mg cm⁻²). Consequently, a maximum power density of 2180 mW m⁻² was finally observed with 80% of COD removal from food-processing wastewater. This work enhances MFC performance by increasing the conductivity and porosity of a ZIF-67/Fe-PPy-based bioanode, providing a practical strategy for wastewater treatment and electricity recovery.