Human activities have resulted in the eutrophication of rivers, leading to heightened concerns regarding the occurrence of filamentous algal blooms. With the increasing utilization of rivers by humans, the occurrence of these nuisance filamentous algae is expected to increase in frequency in the future. Blooms primarily occur due to energy congestion at the trophic level of primary producers, resulting from inefficient energy flow in both the bottom-up and top-down pathways. To investigate the mechanism underlying the outbreak of filamentous algae, two streams in the southern Taihang catchment with different nutrient conditions were selected for this study. The objective of this study was to understand the effects of nutrient levels and other potential factors on the distribution and succession of filamentous algae. Our findings revealed a positive correlation between nutrient conditions and the biomass of filamentous algae. Cladophora and Spirogyra were identified as the dominant species among filamentous algae, each exhibiting unique distribution patterns in the two streams. Spirogyra thrived predominantly in the Baligou stream, where lower nutrient levels and warmer temperatures prevailed. In contrast, Cladophora flourished in the nutrient-rich Nanping stream at colder temperatures. Results from the generalized linear model indicated that the biomass of Cladophora was influenced by nutrient concentration, water depth, water temperature, and macrobenthic biomass. The biomass of Spirogyra, on the other hand, was primarily determined by water temperature, nutrient concentrations, water depth, and velocity. The positive correlation between Cladophora and macrobenthos revealed a possible mutually beneficial relationship, suggesting that macrobenthos may promote the growth of Cladophora by inhibiting periphytic diatoms. In return, the macrobenthos benefit from a secure refuge and an environment conducive to foraging and reproduction. This study suggested that to alleviate energy flow congestion in the benthic food chain, it is advisable to address this issue by either reducing nutrient loadings in rivers or enhancing the presence of benthivorous fishes in streams.

Phosphorus fertilization is employed in some reservoirs to increase fish production. To clarify whether silver carp regulate phosphorus (P) concentration or if fertilizing leads to phytoplankton blooms, a 6-week experiment was conducted with 18 enclosures in Nanwan Reservoir, central China. Treatments were three levels of P concentration (low: 45 μg/L; medium: 90 μg/L; high: 180 μg/L) with or without silver carp stocking (10 g/m³). The effect of silver carp stocking on phytoplankton community changed with P fertilization in the water column. No significant fish effect was observed on total phytoplankton biomass at the low P level, while the chlorophyll a concentration, total phytoplankton biomass, and biomass of phytoplankton > 30 μm were enhanced significantly by silver carp at the medium P level. In addition, at the medium P level, the biomass of Bacillariophyta was significantly greater, whereas the biomass of Chlorophyta was significantly lower in the enclosures with silver carp stocking. Potentially, silver carp enhanced the total phytoplankton biomass by nutrient recycling. Zooplankton had a weak grazing efficiency and had limited effects on control of phytoplankton biomass at the three P levels. The 6-week experiment confirmed that P fertilization could consistently cause greater fish productivity with phytoplankton biomass increasing at the same time. We therefore propose a mechanism for the observed relationship between silver carp stocking and phytoplankton. Under the condition of ambient fish density (10 g/m³), silver carp could not control phytoplankton biomass with phosphorus fertilization; instead, the fish may have promoted phytoplankton growth via nutrient recycling. Silver carp seem to have only a weak effect on the phytoplankton community without P fertilization. Therefore, from the viewpoint of phytoplankton regulation, P fertilization should be considered as a cautious operation for water protection and reasonable fish enhancement.

A new terrestrial diatom species, Mayamaea densestriata sp. nov. , is described from moist agricultural soil in Henan Province, China. Morphologically, it exhibits the typical diagnostic features of the genus Mayamaea , including small, elliptical to linear-elliptical valves, areolae externally occluded with hymenes, uniseriate radiate striae, and a distinct sternum. M. densestriata closely resembles six congeners, including M. atomus , M. terrestris , M. fossalis , M. vietnamica , M. arida , and M. permitis , but can be clearly distinguished by its lanceolate axial area fusing with a transversely expanded central area, higher stria density, and a notably greater number of areolae per stria. Phylogenetic analyses based on concatenated SSU rDNA and rbc L gene sequences strongly support the placement of M. densestriata within the genus Mayamaea . Furthermore, the overall topology also confirms the monophyly of Mayamaea , which is resolved as sister to a clade encompassing species of Pinnularia and Caloneis , thereby supporting its affiliation within the family Pinnulariaceae.

Fucoxanthin is a high-value marine xanthophyll with a unique epoxy-allene structure, predominantly produced by brown macroalgae and marine diatoms, and additionally reported in other heterokont lineages including chrysophytes and certain haptophytes. As a core light-harvesting pigment, it exhibits multiple bioactivities including lipid-lowering, antioxidant, and anti-inflammatory effects, with broad applications in functional foods, dietary supplements, and pharmaceuticals. Currently, over 70% of commercial fucoxanthin is extracted from brown macroalgae such as Saccharina japonica and Undaria pinnatifida. However, due to low endogenous pigment content and significant extraction losses, the industrial yield is only 0.05–0.1% of dry weight, failing to meet the growing downstream demand for stable high-purity supply. Marine diatoms, characterized by short growth cycles, high pigment content, and controllable culture conditions, have emerged as a core direction for industrial upgrading. Among them, Phaeodactylum tricornutum and Odontella aurita are the two most systematically studied high-yield strains with outstanding potential. This review adopts volumetric productivity (mg/(L·d)) as the core evaluation metric, which integrates biomass concentration, pigment content, and production cycle, and reflects industrial efficiency more reliably than single intracellular content data. We summarize high-yield induction methods from the dimensions of nutrient regulation, light optimization, exogenous induction, and strain improvement, and systematically compare downstream processing, safety profiles, and regulatory status between the two diatoms. Furthermore, we evaluate multi-product co-production potential and scale-up performance from a techno-economic perspective. This review provides a side-by-side benchmark of these two marine diatoms, offering a data-driven reference for process development and industrial deployment of microalgae-derived fucoxanthin.

Eukaryotic flagella are evolutionarily conserved organelles that mediate motility, sensory transduction, and environmental adaptation, yet their presence and gene composition vary considerably across algal lineages. Dinoflagellates, a lineage within the superphylum Alveolata, derived from secondary endosymbiosis, exhibit larger and more reorganized genomes than their red-algal relatives and possess a distinctive biflagellate morphology, making them an informative group for studying flagellar evolution. To systematically investigate flagellar gene distribution in this lineage, we performed comparative genomic analyses on 102 genomes spanning four algal groups—Chlorophyta, Rhodophyta, Alveolata (represented by dinoflagellates), and Bacillariophyta. Genomes were selected based on assembly completeness, retaining only those with BUSCO completeness > 50% to balance data quality with taxonomic coverage. Orthologous groups were identified using a reciprocal best BLAST v2.11.0(rBH) strategy, from which we curated 94 conserved flagellar gene families. Quantitative comparisons revealed significant lineage-specific expansions of flagellar gene families within dinoflagellates, including WDR35, TTLL5, and STK36, with fold enrichment values ranging from 3.6 to 5.8 (adjusted p < 0.01). Phylogenetic analyses further identified two axonemal components, BBS9 and C1A-18, as candidates acquired via horizontal gene transfer, with bootstrap support exceeding 80% and Alien Index values > 45. Collectively, these phylogenomic analyses suggest that lineage-specific expansion and horizontal gene transfer have jointly contributed to the evolution of flagellar systems in dinoflagellates, providing a framework for future functional studies.