The Big East Lake water network (BELWN), located in Wuhan city, China, is mainly composed of six lakes and isolated from the Yangtze river. At the background of restoring the hydrological connectivity between rivers and lakes, four season investigations were conducted during 2014–2015 to study the spatial distribution and seasonal dynamics of macroinvertebrate communities, explore their relationships with environmental factors, and forecast the change trends in assemblages in a long period after restoration measures. A total of 40 species were recorded, oligochaetes and chironomids dominated the communities. Season variation in density and biomass were distinct and the community differences in lakes related to the degrees of organic pollution. In comparison with the historical data, the species richness of mollusks in Donghu lake sharply decreased due to water pollution and the loss of diverse habitat. Concerning on the whole BELWN, the whole taxa recorded in our study was slightly fewer than the previous study. A new recorded species polychaete Nephtys sp. was first collected with an important ecological interest. As an urban lake system dominated by eutrophication, the water nutrients significantly affected the distribution of macroinvertebrates. According to the GAM models, the dominant species responded to environmental gradients with different response curves. After restoring the hydrological connectivity between rivers and lakes, the macroinvertebrate communities would change and the biodiversity would steadily increase with time. Additionally, the new recorded species Nephtys sp. would spread into the whole BELWN in the foresee future. Le réseau du Grand lac Est (BELWN), situé dans la ville de Wuhan, en Chine, est principalement composé de six lacs isolés du fleuve Yangtze. Dans le cadre du rétablissement de la connectivité hydrologique entre les rivières et les lacs, quatre études ont été menées pendant la période 2014-2015 pour étudier la répartition spatiale et la dynamique saisonnière des communautés de macroinvertébrés, explorer leurs relations avec les facteurs environnementaux et prévoir les tendances des changements dans les assemblages à long terme après les mesures de restauration. Un total de 40 espèces a été enregistré. Les oligochètes et les chironomides ont dominé les communautés. La variation saisonnière de la densité et de la biomasse était nette et les différences entre lacs dans les communautés étaient liées au degré de pollution organique. Par rapport aux données historiques, la richesse en espèces de mollusques du lac Donghu a fortement diminué en raison de la pollution de l'eau et de la perte de divers habitats. En ce qui concerne l'ensemble du BELWN, le total des taxons rencontrés dans notre étude était légèrement inférieur à celui de l'étude précédente. Une nouvelle espèce polychète Nephtys sp., d'un intérêt écologique important, a été échantillonnée. En tant que système lacustre urbain dominé par l'eutrophisation, les nutriments ont affecté de façon significative la répartition des macroinvertébrés. Selon les modèles GAM, les espèces dominantes ont répondu à des gradients environnementaux avec des courbes de réponse différentes. Après la restauration de la connectivité hydrologique entre les rivières et les lacs, les communautés de macroinvertébrés changeront et la biodiversité augmentera avec le temps. De plus, les nouvelles espèces comme Nephtys sp. se répandront dans tout le BELWN dans l'avenir.

In this study, the comparative effects of the two disturbances (aquaculture and water level fluctuations) on macroinvertebrate communities were explored in two waterbodies connected with the reservoir system of Three Gorges Reservoir (TGR) in China. One water body called Gaoyang Bay which suffered organic pollution from intensive aquaculture. Another named Hanfeng Lake, where the effects of water-level fluctuations are obvious. The results showed that aquaculture could significantly affect the chemical forms of nutrients, decrease the α-diversity and increase the β-diversity of macroinvertebrates although the communities in the treatment area in Gaoyang Bay were not fundamentally changed comparing to the control area in the same bay. The densities of macroinvertebrates in the treatment area were significantly lower than that of the control area. The composition of functional feeding groups in the treatment area was close to that in Hanfeng Lake, but obviously different from that in the control area in Gaoyang Bay and the collectors and predators dominated the communities in this control area with the highest percentages. Although water-level fluctuations had negative effects on the communities by decreasing the α-diversity and increasing the β-diversity, which were confirmed by the values of Simpson index, Shannon-Wiener index and Harrison's index in the control area of Gaoyang bay and Hanfeng Lake, the adverse effects were relative low compared to aquaculture. In the bays of TGR, the small-scale disturbance (aquaculture activities) had more significant negative effects compared to the big-scale disturbance (water-level fluctuations related to dam operation of TGR).

It is imperative that freshwater fish biodiversity research incorporates diverse components, encompassing taxonomy, phylogeny and function, alongside multifaceted facets, including richness, divergence and regularity. This comprehensive approach is essential to facilitate a more profound comprehension of freshwater ecosystem functions, to elucidate the mechanisms underpinning fish community assembly, and to accurately assess the impacts of anthropogenic disturbance. Consequently, this scientific understanding can inform the development of effective fish conservation and ecosystem management strategies. This study utilized environmental DNA metabarcoding to assess the diversity of fish across the entire Yangtze River, encompassing the upper reach (Upper), the Three Gorges Reservoir area (RES_SX), and the downstream reach (Down). The results indicated that 150 distinct fish species were detected, with the RES_SX area exhibiting a significantly lower taxonomic diversity and fish detection rate in comparison to the other two regions. Conversely, phylogenetic and functional diversity exhibited stability post-normalization by taxonomic richness. Furthermore, investigation of the divergence facet of alpha-diversity demonstrated a reduction in clustering and an improvement of overdispersion on the phylogenetic and functional diversity, respectively, in the RES_SX and Down regions. Beta-diversity analysis further revealed lower taxonomic beta-diversity but higher phylogenetic and functional beta-diversity in the RES_SX area. A substantial degree of geographic distance-dependent similarity was identified for all three components of beta-diversity in the Upper Reach. Conversely, these components were found to be disrupted in the Down Reach. Finally, an analysis of the assembly mechanism revealed stochastic processes, dispersal limitation and drift as the dominant factors shaping the fish communities, with reduced dispersal limitation in the RES_SX area. This study provides novel insights into the multidimensional diversity of fish populations in response to dam construction, emphasizing the necessity of integrating multiple facets of diversity for accurate impact assessment and supporting evidence-based conservation of fish species in the Yangtze River.

Phytoplankton blooms recur across lakes, reservoirs, rivers, coastal oceans, and cryospheric systems, with life cycles shaped by system-specific environmental drivers. This review synthesizes how five universal stages—recruitment, proliferation, persistence, decline, and fate—are expressed across systems, highlighting overlooked contrasts. Recruitment is temperature-driven in stratified lakes but governed by hydrodynamic relaxation in rivers and reservoirs. Proliferation is phosphorus-driven in freshwaters and iron-limited in offshore marine systems, where it can also trigger cysteine synthase-mediated neurotoxin production in diatoms. Persistence reflects more than physiological tolerance: bloom-associated microbiomes buffer nutrient supply and may harbor antibiotic resistance genes under warming. Decline is shaped by residence time: slow-retention systems favor viral lysis and internal recycling, whereas fast-flowing systems favor physical export. Bloom fate is reshaped by plastisphere-associated microbial interactions altering organic matter remineralization and carbon export efficiency. In cryospheric environments, blooms are governed by ice physics rather than liquid-water dynamics: recruitment follows ice-melt release, proliferation depends on light duration under meltwater stratification, decline is triggered by refreezing, and fate is amplified through ice-albedo feedbacks. Despite system-specific controls, bloom progression follows five generalized ecological laws: threshold activation, resource-retention optimization, feedback stabilization, disturbance-driven reset, and ecological legacy propagation. Critical gaps remain—quantitative stage-transition thresholds are poorly constrained, phytoplankton physiological plasticity is rarely incorporated into models, and no framework resolves all five stages across the land-sea continuum. Addressing these gaps require trait-based parameterization, high-frequency observational networks, and coupled lake-river-estuary-coastal forecasting models. This framework provides a mechanistic foundation for transferable bloom prediction under climate change and hydrological regulation.