Meta-ecosystem Frameworks Can Enhance Control of the Biotic Transport of Microplastics.

The lack of systematic approaches and analyses to identify, quantify, and manage the biotic transport of microplastics (MPs) along cross-ecosystem landscapes prevents the current goals of sustainable environmental development from being met. This Perspective proposes a meta-ecosystem framework, which considers organismal and resource flows among ecosystems to shed light on the research and management challenges related to both abiotic and biotic MP transport at landscape levels. We discuss MP transport pathways through species movements and trophic transfers among ecosystems and sub-ecosystems, and highlight these pathways in the mitigation of MP pollution. The integration of biotic pathways across landscapes prioritizes management actions for MP transport using diverse approaches such as wastewater treatment and plastic removal policies to mitigate contamination. In addition, our framework emphasizes the potential sink enhancement of MPs through habitat conservation and enhancement of riparian vegetation. By considering the mechanisms of meta-ecosystem dynamics through the processes of biotic dispersal, accumulation, and the ultimate fate of MPs, advances in the environmental impact assessment and management of MP production can proceed more effectively.

Existing levels of biodiversity and river location may determine changes from small hydropower developments.

Global ecosystems are facing anthropogenic threats that affect their ecological functions and biodiversity. However, we still lack an understanding of how biodiversity can mediate the responses of ecosystems or communities to human disturbance across spatial gradients. Here, we examined how existing, spatial patterns of biodiversity influence the ecological effects of small hydropower plants (SHPs) on macroinvertebrates in river ecosystems. This study found that levels of biodiversity (e.g., number of species) can influence the degrees of its alterations by SHPs occurring along elevational gradients. The results of the study reveal that the construction of SHPs has various effects on biodiversity. For example, low-altitude areas with low biodiversity (species richness less than 12) showed a small increase in biodiversity compared to high-altitude areas (species richness more than 12) under SHP disturbances. The increases in the effective habitat area of the river segment could be a driver of the enhanced biodiversity in response to SHP effects. Changes in the numerically dominant species contributed to the overall level of community variation from disturbances. Location-specific strategies may mitigate the effects of SHPs and perhaps other disturbances.

A global agenda for advancing freshwater biodiversity research.

Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation.

[Correlation between TCF7L2 gene polymorphism and genetic susceptibility in women with gestational diabetes mellitus].

OBJECTIVE: To investigate the relationship between single nucleotide polymorphism (SNP) of transcription factor 7-like 2 (TCF7L2) at locus rs7903146, rs290487, rsl1196205, rs12255372 and genetic susceptibility in women with gestational diabetes mellitus (GDM). METHODS: As a case- control study, 100 pregnant women with GDM and 100 healthy pregnant women in the Maternal and Children Health Hospital of Jiangxi Province were recruited from January 2010 to July 2013. Clinical parameters, including body mass index (BMI), fasting insulin (FINS), fasting plasma glucose (FPG) and homeostatic model assessment-insulin resistance index (HOMA-IR) were measured after admission to hospital. Allelespecific PCR was used to analyze the SNP of TCF7L2 at locus rs7903146, rs290487, rs11196205, rs12255372. RESULTS: (1)The BMI, FPG, FINS and HOMA-IR in GDM group were (27.4 ± 3.0)kg/m², (5.6 ± 1.0) mmol/L, (6.2 ± 3.4) mU/L and 1.8 ± 1.0, and were (24.2 ± 2.9) kg/m², (5.3 ± 0.8) mmol/L, (4.5 ± 2.8) mU/L, 1.2 ± 0.8 in the control group, respectively. The differences had statistically significance (P < 0.05). (2)The SNP of TCF7L2 gene, locus rs7903146 were CC, CT and TT genotype; the SNP of locus rs290487 were CC, CT and TT genotype; and the SNP of locus rs11196205 were GG and CC genotype; while the SNP of locus rs12255372 was GG genotype. (3) The distribution frequencies of genotype CC, CT and TT at locus rs7903146 in the GDM group were 40% (40/100), 36% (36/100) and 24% (24/100), respectively. While in the control group, they were 55% (55/100), 38% (38/100) and 7% (7/100), respectively. The frequencies of C and T allele of rs7903146 were 58%and 42% in the GDM group, and in the control group they were 74% (148/200) and 26% (52/200). The differences of genotype distribution and C/T allele frequency of rs7903146 between the two groups were statistically significant (P < 0.05). (4) The distribution frequencies of genotype CC, CT and TT at locus rs290487 in the GDM group were 12% (12/100), 36% (36/ 100) and 52% (52/100), and were 16% (16/100), 34% (34/100)and 50% (50/100) in the control group. The frequencies of C and T allele of rs290487 were 30% (60/200) and 70% (140/200) in the GDM group, and were 33% (66/200) and 67% (134/200) in the control group. There was no difference of genotype distribution and C/T allele frequency of rs290487 between the two groups (P > 0.05). (5)The distribution frequencies of genotype GG and CC at locus rs11196205 in the GDM group were 99% (99/100) and 1% (1/100), while those in the control group were 100% (100/100)and 0%. The frequency of G and C allele of rs11196205 were 99% (198/200) and 1% (2/200) in the GDM group, while in the control group were 100% (200/200) and 0. There was no difference of genotype distribution and G/C allele frequency of rs11196205 between the two groups (P > 0.05). (6)The distribution frequencies of genotype GG at locus rs12255372 were 100% (100/100) in both the GDM group and the control group. The frequencies of G allele of rs12255372 were 100% (200/200) in both the GDM group and the control group. There was no difference of genotype distribution and G allele frequency of rs12255372 between the two groups (P > 0.05). (7) After adjusting for age, gestational age, BMI, FPG and FINS, pregnant women with TT genotype at locus rs7903146 were more likely to have hyperglycemia compared with the C allele carriers (OR = 2.77, 95% CI: 1.03-7.57, P < 0.05). CONCLUSIONS: The polymorphism of locus rs7903146 in TCF7L2 gene may be associated with genetic susceptibility in women with GDM. TT genotype is likely to be risk factor in the pathogenesis of GDM.

Description of Chlorogomphus auripennis spec. nov. from Guangdong Province, with new records of Chlorogomphidae from Yunnan Province, China (Odonata: Chlorogomphidae).

A new chlorogomphid, Chlorogomphus (Orogomphus) auripennis spec. nov. (holotype male; Mt Nankunshan, Longmen County, Guangdong Province, China, 20. V. 2008) is described and illustrated. It is the first species belonging to the subgenus Orogomphus recorded from mainland China. The holotype will be deposited in the Collection of Aquatic Animals, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan City, Hubei Province, China. Chlorogomphus auratus Martin, 1910 and Chloropetalia selysi (Fraser, 1929) are recoded from Chinese territory for the first time. The total number of Chlorogomphidae in China reaches 20. Description of the hitherto unknown female of Chlorogomphus yokoii Karube, 1995 is provided.

Aeshna shennong sp. nov., a new species from Hubei Province, China (Odonata: Anisoptera: Aeshnidae).

Aeshna shennnong sp. nov. (holotype male: Dajiuhu national wetland park in Shennongjia National Nature Reserve, Shennongjia City, Hubei Province, China, 28. VIII. 2013) is described, illustrated and compared with its most similar congener, A. petalura Martin, 1908. The holotype will be deposited in the Collection of Aquatic Animals, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan City, Hubei Province, China. New distribution records of A. petalura from mainland China are also provided.

Daily process and key characteristics of phytoplankton bloom during a low-water level period in a large subtropical reservoir bay.

Reservoirs, heavily influenced by artificial management, often harbor phytoplankton assemblages dominated by cyanobacteria or dinoflagellates, triggering significant changes in aquatic ecosystems. However, due to limited sampling frequency and insufficient attention to species composition, the bloom processes and key characteristics of phytoplankton community structure have not been systematically elucidated. During the low-water level period when blooms are most likely to occur (June to September) in a tributary bay of the Three Gorges Reservoir, daily sampling was conducted to investigate phytoplankton community composition, identify significant environmental factors, and evaluate important structure characteristics of phytoplankton community. The results showed that Microcystis aeruginosa maintained a clear dominance for almost a month in stage 1, with low Shannon and evenness but a high dominance index. Phytoplankton total density and biomass decreased drastically in stage 2, but Microcystis aeruginosa still accounted for some proportion. The highest Shannon and evenness but the lowest dominance index occurred in stage 3. Peridiniopsis niei occurred massively in stage 4, but its dominant advantages lasted only one to two days. NH4-N was responsible for the dominance of Microcystis aeruginosa, while TP and PO4-P was responsible for the dominance of Peridiniopsis niei; however, precipitation contributed to their drastic decrease or disappearance to some extent. The TN : TP ratio could be considered as an important indicator to determine whether Microcystis aeruginosa or Peridiniopsis niei dominated the phytoplankton community. Throughout the study period, physiochemical factors explained more variation in phytoplankton data than meteorological and hydrological factors. Pairwise comparisons revealed an increase in average ß diversity with stage progression, with higher ß diversities based on abundance data than those based on presence/absence data. Repl had a greater effect on ß diversity differences based on presence/absence data, whereas RichDiff had a greater effect on ß diversity differences based on species abundance data. Co-occurrence networks for stage 1 showed the most complex structure, followed by stage 4, while the network for stage 3 was relatively sparse, although the overall community division remained compact. This study provides a useful attempt to explore the status and changes in phytoplankton community structure during the bloom process through high-resolution investigation.

Distinct differences of vertical phytoplankton community structure in mainstream and a tributary bay of the Three Gorges Reservoir, China.

The vertical distribution of phytoplankton plays a crucial role in shaping the dynamics and structure of aquatic communities. In highly dynamic reservoir systems, water level fluctuations significantly affect the physiochemical conditions and the phytoplankton community. However, the specific effects on the vertical characteristics of phytoplankton between the mainstream and the tributary bay of the reservoir remain unstudied. This study investigated the vertical aspects of phytoplankton density, biomass, α and ß diversity through monthly sampling over two years in the mainstream (Chang Jiang, CJ) and a tributary bay (Xiang Xi, XX) of the Three Gorges Reservoir in China. Phytoplankton density and biomass were significantly higher in XX, indicating an increased risk of algal blooms in the tributary. The phytoplankton community in CJ showed more stable species-environment relationships, a lower Shannon index and a higher evenness index, suggesting a relatively simple structure and a more uniform distribution of phytoplankton among different water layers. Conversely, XX showed greater differences between water layers (higher ß diversity), with significant negative correlations with water level and positive correlations with DO difference, dissolved silica (DSi) difference, and stratification. Peak phytoplankton density and biomass, as well as high ß diversity in XX, occurred during periods of decreased water levels with strong stratification in spring and summer. A structural equation model complemented by path analysis revealed that a decrease in water level could increase ß diversity either directly through internal processes with extended residence time or indirectly by modifying stratification and the vertical distribution of DSi in XX. Therefore, a proposed water quality management strategy for XX was to increase the water level or reduce ß diversity by implementing artificial mixing during stratification periods. Overall, this study lies in its comprehensive investigation of the vertical characteristics of the phytoplankton community in both the mainstream and the tributary bay of the Three Gorges Reservoir, elucidating the significant impact of water level fluctuations and providing insights for targeted water quality management strategies in the tributary bay to mitigate potential ecological impacts.

Long-term (2003-2021) evolution trend of water quality in the Three Gorges Reservoir: An evaluation based on an enhanced water quality index.

The degradation of water quality induced by the construction of large-scale hydraulic projects is one of the primary public concerns; however, it is rarely addressed with long-term field observation data. Here, we reported the long-term (2003-2021) trends, seasonal patterns, and overall condition of water quality of the Three Gorges Reservoir (TGR) with an enhanced water quality index (WQI). Specifically, to emphasize the importance of the biological role in water quality assessment, chlorophyll-a (Chla) was incorporated into WQI, and then a novel workflow using machine learning approach based on Random Forest (RF) model was constructed to develop a minimal water quality index (WQImin). The enhanced WQI indicated an overall "good" water quality condition, exhibiting a gradually improving trend subsequent to the reservoir impoundment in 2003. Meanwhile, the assessment revealed that the water quality has discernible seasonal patterns, characterized by poorer conditions in the spring and summer seasons. Furthermore, the RF model identified Chla, dissolved oxygen (DO), ammonium nitrogen (NH4-N), water temperature (WT), pH, and total nitrogen (TN) as key parameters for the WQImin, with Chla emerging as the most important factor in determining WQImin in our study. Moreover, weighted WQImin models exhibited improved performance in estimating WQI. Our study emphasizes the importance of biological parameters in water quality assessment, and introduces a systematic workflow to facilitate the development of WQImin for accurate and cost-efficient water quality assessment. Furthermore, our study makes a substantial contribution to the advancement of knowledge regarding long-term trends and seasonal patterns in water quality of large reservoirs, which provides a foundational basis for guiding water quality management practices for reservoirs worldwide.

Species turnover and functional nestedness constitute the geographic patterns of stream diatoms in the Three Parallel Rivers region, China.

Unraveling biodiversity patterns and their driving processes is paramount in ecology and biogeography. However, there remains a limited understanding regarding the underlying mechanisms of community assembly, particularly in alpine streams where significant elevation gradients and habitat heterogeneity exist. We investigated the patterns and drivers of beta diversity, explicitly focusing on taxonomic and functional diversity, in the three parallel rivers region in China. We employed a beta diversity partitioning approach to examine the turnover and nestedness components of beta diversity and further deconstructed the diatom community into attached and unattached groups. Our results revealed distinct diversity patterns and drivers for taxonomic and functional beta diversity. Specifically, taxonomic beta diversity was mainly driven by the turnover component affected by spatial processes, whereas functional beta diversity was dominated by the nestedness component affected by environmental processes. Furthermore, our analysis of the division of the whole communities demonstrated that the varying responses of benthic diatoms with different attached abilities to environmental filtering, dispersal limitation, and directional flow were the essential reasons for shaping the biodiversity patterns of species turnover and functional nestedness in the alpine stream. Our findings suggested that partitioning beta diversity and dividing the entire community can more deeply infer underlying community assembly processes, thereby providing valuable insights into understanding biodiversity patterns, drivers, and conservation strategies.

Increased co-expression of ICOS and PD-1 predicts poor overall survival in patients with acute myeloid leukemia.

BACKGROUND: Inducible co-stimulatory factor (ICOS) has a dual role: activating cytotoxic T cells against tumors or exacerbating immunosuppression of regulatory T cells (Tregs) to participate in immune evasion. However, the correlation between ICOS and its co-expression with inhibitory immune checkpoints (IICs) and prognosis in acute myeloid leukemia (AML) is little known. METHODS: The prognostic importance of ICOS and IICs in 62 bone marrow (BM) samples of de novo AML patients from our clinical center (GZFPH) was explored and then the RNA sequencing data of 155 AML patients from the Cancer Genome Atlas (TCGA) database was used for validation. RESULTS: In both GZFPH and TCGA cohorts, high expression of ICOS was significantly associated with poor overall survival (OS) in patients with AML (P < 0.05). Importantly, co-expression of ICOS and PD-1, PD-L1, PD-L2, CTLA-4, and LAG-3 predicted poor OS in AML; among them, ICOS/PD-1 was the optimal combination of immune checkpoints (ICs). The co-expression of ICOS and PD-1 was correlated with poor OS in non-acute promyelocytic leukemia (non-APL) patients following chemotherapy. Additionally, ICOS/PD-1 was an independent OS-predicting factor (P < 0.05). Notably, a nomogram model was constructed by combining ICOS/PD-1, age, European Leukemia Net (ELN) risk stratification, and therapy to visually and personalized predict the 1-, 3-, and 5-year OS of patients with non-APL. CONCLUSION: Increased expression of ICOS predicted poor outcomes, and ICOS/PD-1 was the optimal combination of ICs to predict outcomes in patients with AML, which might be a potential immune biomarker for designing novel AML therapy.

Discovery of four new species of the genus Planaeschna from Southwestern China (Odonata: Anisoptera: Aeshnidae).

Four new species of the genus Planaeschna, P. robusta sp. nov. (holotype male; Mt. Emeishan, Emeishan City, Sichuan Province, China, 16. VIII. 2007), P. maculifrons sp. nov. (holotype male; Mt. Emeishan, Emeishan City, Sichuan Province, China, 20. VIII. 2007), P. caudispina sp. nov. (holotype male; Mt. Qingchengshan, Dujiangyan City, Sichuan Province, China, 30. VIII. 2007) and P. monticola sp. nov. (holotype male; Sanjiacun Stream, Fengyi Town, Dali City, Yunnan Province, China, 19. XI. 2012) are described and illustrated and diagnosed from their congeners. All the holotypes have been deposited in the Collection of Aquatic Animals, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan City, Hubei Province, China. Brief notes on the biology of each species are also provided.

A new species of Siphlonurus Eaton, 1868 (Ephemeroptera, Siphlonuridae) from Yunnan, China.

Siphlonurusdongxi Li & Tong, sp. nov. from Shangri-La City, Yunnan Province, China, is described based on egg, nymph, and winged stages. The new species is closely related to S.davidi (Navás, 1932), and can be distinguished by the colour of the imago, the forking point of MP, the penis, posterolateral spines of tergum IX of imagoes, and first abdominal terga nymph, as well as the structure of the egg. The new species and S.davidi have the same morphological and structural characteristics, such as the long cubital area with many intercalaries, cross veins between C, Sc, RA, and RSa1 surrounded with distinct pigments, the strong curvature of vein CuP in the forewing, the broad expansion of the hindwing, the membranous penis lobes fused without teeth, supporting the proposition of a new species complex, the Siphlonurusdavidi group. The structures of the penis and the egg of the new species could help understand the origin and evolution of the genus Siphlonurus.

Integrated top-down and bottom-up proteomics mass spectrometry for the characterization of endogenous ribosomal protein heterogeneity.

Ribosomes are abundant, large RNA-protein complexes that are the sites of all protein synthesis in cells. Defects in ribosomal proteins (RPs), including proteoforms arising from genetic variations, alternative splicing of RNA transcripts, post-translational modifications and alterations of protein expression level, have been linked to a diverse range of diseases, including cancer and aging. Comprehensive characterization of ribosomal proteoforms is challenging but important for the discovery of potential disease biomarkers or protein targets. In the present work, using E. coli 70S RPs as an example, we first developed a top-down proteomics approach on a Waters Synapt G2 Si mass spectrometry (MS) system, and then applied it to the HeLa 80S ribosome. The results were complemented by a bottom-up approach. In total, 50 out of 55 RPs were identified using the top-down approach. Among these, more than 30 RPs were found to have their N-terminal methionine removed. Additional modifications such as methylation, acetylation, and hydroxylation were also observed, and the modification sites were identified by bottom-up MS. In a HeLa 80S ribosomal sample, we identified 98 ribosomal proteoforms, among which multiple truncated 80S ribosomal proteoforms were observed, the type of information which is often overlooked by bottom-up experiments. Although their relevance to diseases is not yet known, the integration of top-down and bottom-up proteomics approaches paves the way for the discovery of proteoform-specific disease biomarkers or targets.

Optimal combination of immune checkpoint and senescence molecule predicts adverse outcomes in patients with acute myeloid leukemia.

BACKGROUND: High expression of immune checkpoints (ICs) and senescence molecules (SMs) contributes to T cell dysfunction, tumor escape, and progression, but systematic evaluation of them in co-expression patterns and prognosis in acute myeloid leukemia (AML) was lacking. METHODS: Three publicly available datasets (TCGA, Beat-AML, and GSE71014) were first used to explore the effect of IC and SM combinations on prognosis and the immune microenvironment in AML, and bone marrow samples from 68 AML patients from our clinical center (GZFPH) was further used to validate the findings. RESULTS: High expression of CD276, Bcl2-associated athanogene 3 (BAG3), and SRC was associated with poor overall survival (OS) of AML patients. CD276/BAG3/SRC combination, standard European Leukemia Net (ELN) risk stratification, age, and French-American-British (FAB) subtype were used to construct a nomogram model. Interestingly, the new risk stratification derived from the nomogram was better than the standard ELN risk stratification in predicting the prognosis for AML. A weighted combination of CD276 and BAG3/SRC positively corrected with TP53 mutation, p53 pathway, CD8+ T cells, activated memory CD4+ T cells, T-cell senescence score, and Tumor Immune Dysfunction and Exclusion (TIDE) score estimated by T-cell dysfunction. CONCLUSION: High expression of ICs and SMs was associated with poor OS of AML patients. The co-expression patterns of CD276 and BAG3/SRC might be potential biomarkers for risk stratification and designing combinational immuno-targeted therapy in AML.Key MessagesHigh expression of CD276, BAG3, and SRC was associated with poor overall survival of AML patients.The co-expression patterns of CD276 and BAG3/SRC might be potential biomarkers for risk stratification and designing combinational immuno-targeted therapy in AML.

Hydrological Season Can Have Unexpectedly Insignificant Influences on the Elevational Patterns of Functional Diversity of Riverine Macroinvertebrates.

Spatial biodiversity is a key issue in biogeography for the explorations of biological origin and diversification. However, seldom studies have addressed the temporal changes in spatial patterns of biodiversity. We explored the taxonomic and functional diversities of riverine macroinvertebrates in central China, with the elevational gradient, in different seasons in a normal climate year (i.e., no extreme anomalies in the annual precipitation or average annual temperature). The air temperature and streamflow discharge were decreased monotonically with the increase of elevation both in the dry and wet seasons. In addition, the total nitrogen had no significant change with the increase of elevational gradient in the dry season but showed a monotonically decreasing pattern in the wet season. The total phosphorus showed a monotonically decreasing pattern with the elevational gradient in the dry season but had no significant change in the wet season. The spatial pattern of taxonomic diversity of macroinvertebrates along the elevational gradient showed complex patterns, but the functional diversity had either the unimodal or monotonically decreasing pattern. In addition, the functional diversity with the elevational gradient had similar patterns between the dry and wet seasons. Further analysis of the elevational pattern in different seasons is an important basis for understanding the status quo of functional diversity and formulating countermeasures for biodiversity conservation.

Nonlinear causal analysis reveals an effective water level regulation approach for phytoplankton blooms controlling in reservoirs.

Reservoirs are a rapidly increasing water body providing water supply, irrigation, and many other benefits for human societies globally. However, due to changes in hydrological conditions, building reservoirs tends to bring adverse effects such as eutrophication and phytoplankton blooms, reducing the ecosystem service values. This study focuses on using the empirical dynamic modeling (EDM), an emerging approach for nonlinear analysis, to investigate the nonlinear causal relationship of water level fluctuation (WLF) on phytoplankton biomass and then develop a quantitative model guiding effective phytoplankton blooms controlling based on water level regulations in reservoirs. Specifically, with 9-year continued daily observed data in the Three Gorges Reservoir, we examined the causal effects of different WLF parameters on the dynamics of phytoplankton blooms for the first time. We found that the water level change in the past 24 h (ΔWL) has the strongest causal effect on the daily dynamics of phytoplankton biomass among all WLF parameters (ΔWL, |ΔWL|, and the water level), with a time lag of 2 days. Moreover, EDM revealed a nonlinear relationship between ΔWL and daily dynamics of phytoplankton biomass and achieved a successful prediction for the chlorophyll a concentration 2-day ahead. Further scenario analyses found that both the rise and fall of water level will significantly reduce the chlorophyll a concentration when phytoplankton blooms occur. Nevertheless, on the whole, the rising water level has a more substantial effect on phytoplankton blooms than falling the water level. This result reveals that regulating ΔWL is a simple and effective approach in controlling phytoplankton blooms in reservoirs. Our study reported the nonlinear causal effect of ΔWL on the dynamics of chlorophyll a and provided a quantitative approach guiding effective phytoplankton blooms controlling based on the water level regulation, which might have a broad application in algal blooms controlling in reservoirs and similar waterbodies.

Maximizing fucoxanthin production in Odontella aurita by optimizing the ratio of red and blue light-emitting diodes in an auto-controlled internally illuminated photobioreactor.

Fucoxanthin has multiple beneficial effects on human health. However, an efficient cultivation strategy for hyper-production of microalgae-based fucoxanthin has been seldom achieved. Here, an auto-controlled photobioreactor (PBR) installed internal light-emitting diodes illumination with adjustable spectra ratio was firstly used to culture Odontella aurita. The results showed that red light (RL) was more suitable for cell growth and fucoxanthin accumulation than blue light (BL) and white light. The biomass and fucoxanthin production were further promoted by optimizing the ratios of RL and BL, with 8:2 giving the highest productivities of 570 and 9.41 mg L-1 d-1, respectively, which is the highest fucoxanthin productivity ever reported under photoautotrophic cultivation. Pilot-scale cultivation demonstrated its promising feasibility in commercial fucoxanthin production. Our study represents a pioneering work of harnessing the PBR with internal illumination for hyper-production of microalgae-based fucoxanthin, and provides feasible strategies for high-efficient production of other value-added products in related species/strains.

Small run-of-river hydropower dams and associated water regulation filter benthic diatom traits and affect functional diversity.

Knowledge of benthic diatom traits can help understand ecosystem function and guide biodiversity conservation. This is particularly important in rivers on which there are small run-of-river dams, which currently receive less attention. These dams generate power by drawing water from upstream and discharging it downstream after a large drop in penstock. We examine 15 functional diatom traits in habitats upstream, surrounding, and downstream of 23 small run-of-river dams in Xiangxi River, China. We compare the effects of these small dams on benthic diatom species traits, and taxonomic and functional diversity, from 90 sites. Dams change local environmental (e.g., channel width, flow velocity, depth) and physicochemical (e.g., dissolved oxygen, water temperature) variables, and a shift in diatom life forms and guilds is apparent, from taxa with strong attachment and low profile in high velocity waters (i.e., H1, H2 and H4) to those with weak attachment or that are planktonic below dams and outlets (i.e., H3 and H5), and towards high profile taxa below dams. Significant differences in biodiversity, particularly in functional richness, redundancy, and evenness, are apparent. Species and functional diversity indices are influenced by physical and chemical environmental factors (especially flow velocity and water depth). We found that diatom functional traits reflect longitudinal changes in flow and ecological condition, and suggest that monitoring such traits could be useful in adjusting flows to minimize ecosystem impacts. To maintain ecological flow and reasonable water depth within rivers we advocate for improved connectivity, carrying capacity and resilience of water ecosystems via a long-term, trait-based understanding of the impacts of small run-of-river dams.

Species dispersal along rivers and streams may have variable importance to metapopulation structure.

The ability to prioritize habitats that have spatially varied contributions to species persistence can produce synergistic benefits for regional conservation efforts. However, conservation in spatially diverse landscape-networks requires considering dispersal asymmetry in the context of ecological connectivity and metapopulation persistence. By developing an approach based on metapopulation theory, this study prioritized the importance of habitat (as determined by the habitat quality and spatial position in networks) on metapopulation structure in mountainous streams. As a case study, we examined dispersal via overland and instream networks in a riverine mayfly Rhithrogena sp. cf. japonica in a mountain range of Southwest China. Compared to flow velocity, water depth, and instream nutrient-levels, water temperature was a key factor in determining local habitat suitability for R. sp. cf. japonica. Higher water temperature was linked to poor habitat suitability. Instream pathways were the main dispersal corridors compared with overland movement between tributaries for this mayfly. In basins on the east aspect of this mountain range, either monotonically increasing (i.e., never decreasing) or unimodal (i.e., with a single peak) patterns demonstrated the importance of riverine habitats that occur along elevational gradients. However, the importance of habitat appeared to show no definite patterns with elevation on the west aspect. In terms of metapopulation structure, local quality of habitat contributed more to the regional importance of habitat than its spatial position in the networks. The framework presented highlights that the importance of riverine habitats may be quite variable in species having directional dispersal networks across the fluvial landscape in mountainous areas. Results from this framework can serve as the basis to apply a mechanistic understanding to managing and protecting native populations through regional restoration actions.