摘要: In the face of multiple, co-varying environmental threats, measuring anthropogenic impacts and species responses to them is essential for developing biomonitoring programs and for biodiversity conservation. One way of investigating species responses to different conditions is through indicator species indexes. In this context, we investigated zooplankton species indicators of system type (stream or pond), and the most responsive zooplankton indicators of land use changes (pasture and forest) and water quality (oxygen, pH, temperature, and conductivity) within each system type. We studied 221 sites (162 streams and 59 ponds) across one region of Acre state and seven regions of Pará state, Brazil. We sampled zooplankton and physical and chemical variables at each site and determined land use through digital image processing. We recorded 190 taxa (112 Rotifera, 57 Cladocera, and 21 Copepoda). Thirteen species were pond indicators but none were stream indicators. Several species were indicators of land use and water quality in streams; for example, Disparalona tenuispina indicated highly forested streams and Alonella clathratula and Nicsmirnovius pagii indicated high pasture levels. In ponds, Ephemeroporus barroisi and Lecane doryssa indicated moderate pasture levels and no species indicated forested ponds. Temperature, pH, conductivity, and oxygen were the main drivers of species richness. Our results demonstrate that species-specific responses, rather than assemblage-level patterns, offer insights into the ecological status of these aquatic systems. Furthermore, landscape variables, such as forest and pasture cover, influence the selection of specific zooplankton species in streams but not in ponds. However, forested ponds had the highest species richness. Finally, we highlight the role of certain zooplankton species as sensitive bioindicators of ecosystem health.

摘要: Habitat heterogeneity creates diverse habitats and resource distributions that affect community structure and dynamics. More environmentally heterogeneous areas are expected to support more diversified biological communities. However, environmental gradients induced by human activities can result in habitat homogenization, ultimately reducing biotic diversity and increasing biotic homogenization. Our objective was to evaluate whether increased anthropogenic disturbance reduces the diversity of aquatic macroinvertebrates by decreasing habitat heterogeneity. We sampled 40 randomly selected stream sites in the Atlantic Forest and Cerrado biomes surrounding one of the largest reservoirs in Brazil. We calculated 36 physical habitat metrics and used taxonomic and functional Hill numbers as response variables. Those Hill numbers indicated that increased anthropogenic disturbance reduced the diversity of aquatic invertebrates by decreasing habitat heterogeneity, for both rare and common taxa. The most-disturbed sites had a higher proportion of fine substrates and substrate embeddedness, but lower riparian vegetation cover. In contrast, the least-disturbed sites had higher proportions of shelters, riparian and channel canopy cover, benthic leaf litter, and pools. Our approach using taxonomic and functional Hill numbers proved effective in evaluating how environmental heterogeneity affects diversity along anthropogenic disturbance gradients. Consequently, this method can be employed by catchment and stream managers to enhance the effectiveness of stream ecosystem rehabilitation efforts.

摘要: Harmful algal bloom (HAB) mitigation using microorganisms faces challenges, like inconsistent algicidal efficacy, scalability issues, limited microbial diversity, and traditional modeling constraints. To address these challenges, for the first time, this study investigates the quantitative impacts of microorganisms on HABs using machine learning (ML). We conducted an analysis of over 100 microbial species, laying the foundation to optimize treatments for more consistent outcomes. Our findings showed that these microorganisms exhibited an average algicidal ratio of 71 ​% against HABs. Random Forest, Bagging, and Extreme Gradient Boosting Regressors ML models demonstrated robust predictive performance for algicidal ratios. Nonlinear relationships with time, microbial concentrations, and algal biomass were observed. Optimal culture time for maximizing algicidal ratios ranged from 7 to 10 days; extending time did not enhance the algicidal process. The optimum concentration of microorganisms was identified as 0.5 ​× ​10¹⁰ ​cells/mL, with higher concentrations showing diminishing returns. Additionally, algal biomass influenced the algicidal process, with a sharp decline in algicidal ratio at low biomass levels (0–1 ​× ​10⁷ ​cells/mL), followed by stabilization at higher densities (1.5 ​× ​10⁷ ​cells/mL). Algal biomass, culture time, Brevibacillus, microbial concentration, Enterobacter, Microcystis aeruginosa, and Alexandrium tamarense emerged as crucial factors driving microbial algicidal processes against HABs. Overall, ML analysis of microbial impacts on HABs guides effective treatment optimization with future work emphasizing real-world field applications.

摘要: Mandarin fish (Siniperca chuatsi) is an economically important fish in China, and females grow faster than males. Thus, it is critical to obtain neo-male individuals for breeding all-female mandarin fish. In this study, functionalized SWCNTs (single-walled carbon nanotubes) were used as a plasmid carrier to immerse juvenile all-female mandarin fish at plasmid concentrations of 10, 20, and 40 ​mg/L. In muscle and gonad tissues, the DNA of pcDNA4.0-amh could be detected in the SWCNTs-pcDNA4.0-amh-40 mg group at 7 days after the immersion bath. Additionally, the transcription of pcDNA4.0-amh could be detected at 7 and 14 days after the immersion bath. At 60, 90, and 120 days post-immersion, histological analysis revealed that masculinized gonads could be observed in some fish in the SWCNTs-pcDNA4.0-amh-40 mg and SWCNTs-pcDNA4.0-amhy-40 mg groups. In these masculinized gonads, the expression of the foxl2 and cyp19a1a genes decreased significantly, while the expression of the amh and dmrt1 genes increased significantly. Moreover, a dual-luciferase reporter assay revealed that both amh and amhy could activate the promoter of dmrt1 via the amhrII/smads pathway in vitro. Overall, this study demonstrated that functionalized SWCNTs could act as an effective tool to deliver plasmids into the gonads of fish, and that amh and amhy are both important genes in the regulation of sex determination and differentiation in mandarin fish.

摘要: The mitochondrial antiviral signaling protein (MAVS) plays a pivotal role in the interferon (IFN) activation signaling pathway, which culminates in the production of IFN and the establishment of a positive feedback loop. The unrestricted expression of IFN has been demonstrated to result in the development of autoimmune diseases, therefore IFN must be subject to strict regulation. The present study reports a novel mechanism by which IFN expression is negatively regulated in fish by LIM and SH3 protein 1 (LASP1). In the aftermath of infection with the spring viremia of carp virus (SVCV), a substantial increase in lasp1 mRNA levels was observed. Furthermore, overexpression of LASP1 led to a reduction in IFN expression, thereby facilitating SVCV replication. Conversely, the knockdown of LASP1 resulted in an augmentation of the ability of cells to produce IFN, thus attenuating SVCV replication. Subsequent research revealed that LASP1 bound and degraded MAVS via autophagic degradation. Subsequent analysis of the mechanism revealed that LASP1 preferentially associated with a selective autophagy receptor, a neighbor of BRCA1 (NBR1), which facilitated the autophagy degradation of MAVS. Finally, the degradation cascade mediated by LASP1 facilitates SVCV infection by blocking the MAVS-mediated innate signaling pathway. In conclusion, these data reveal LASP1 to act as a negative regulator of the host's innate immune responses to SVCV infection and provide insights into the selective autophagy and innate signaling pathways.

摘要: Water quality is a key driver of aquatic ecosystem health and strongly influences macroinvertebrate assemblages. In the Philippines, the relationship between macroinvertebrates and water quality remains understudied, and macroinvertebrate-based bioassessment is rarely applied. This study analyzed macroinvertebrate and water quality data from 36 streams in Cagayan Valley, Cebu Province, and Caraga to explore biotic responses to environmental gradients. Canonical Correspondence Analysis (CCA) and Threshold Indicator Taxa Analysis (TITAN) identified five key water quality drivers: biological oxygen demand (BOD), chloride, fecal coliform, nitrate, and phosphate. Twenty-one indicator taxa were identified, with 13 showing negative (sensitive) and eight positive (tolerant) responses to these variables. Based on taxon-specific change points and confidence intervals derived from TITAN, six additional taxa were proposed for inclusion in an adapted Biological Monitoring Working Party index for the Philippines (BMWP-Ph). The updated scoring system was evaluated against other regional BMWP versions (e.g., Viet, Thai, UK), showing superior discriminatory efficiency in distinguishing least-disturbed from disturbed stream conditions. This study demonstrates the value of integrating local ecological thresholds into bioassessment tools and highlights the utility of TITAN in identifying taxa responses in tropical freshwater systems. BMWP-Ph represents a functional, evidence-based framework that can be expanded and refined as taxonomic expertise and biomonitoring infrastructure improve in the country.

摘要: The rice field eel, Monopterus albus, is an economically valuable aquaculture fish. However, the shortage of rice field eel fry, which mainly rely on fishing in the wild, is the main bottleneck in the development of the eel industry. Establishing surrogate reproduction technology for the rice field eel is expected to resolve the constraints of the fry shortage. In this study, specific fluorescent labeling of rice field eel primordial germ cells (PGCs) was accomplished by injecting GFP-nanos3’ UTR mRNA. Rice field eel PGCs used for transplantation were then isolated using flow cytometry. Through knocking down common carp dead end (dnd), the key gene involved in the development of PGC, we obtained germ cell-deficient carp recipients for inter-order transplantation of rice field eel PGCs. Immunofluorescence and reverse transcription-PCR results showed that PGCs were completely deleted in carps with dnd gene knocked down. The isolated eel PGCs were transplanted into carp juveniles that lacked endogenous germ cells. Immunofluorescence and reverse transcription-nested PCR results showed that eel germ cells were found in the gonads of 12-month post-transplantation carps, indicating that some eel germ cells colonized and survived in carp gonads. This study has established a germ cell transplantation technology between the Synbranchiformes and Cypriniformes, paving the way for resolving the constraints of the fry shortage in rice field eel aquaculture.

摘要: Ecohydraulics is a scholarly discipline and community of practice that represents the intersection of ecology and hydraulics/fluid dynamics. Although understanding the intersection of ecology and hydraulics is of fundamental interest, it is also highly relevant to the management and conservation of freshwater life and ecosystems, and consistent with calls for more integrative thinking. Here we provide an overview of the ways in which ecohydraulics has the potential to contribute to supporting the protection and recovery of freshwater biodiversity. For example, ecohydraulics can be used to identify environmental flows that benefit aquatic life while enabling hydroelectric generation. In the context of invasive species, ecohydraulics can be used to identify trapping designs that select invasive species whereas for reducing exploitation, it can be used to inform selective fishing gear designs. In terms of water quality management, ecohydraulics can inform the design of stormwater infrastructure that supports freshwater life. Habitat restoration can be guided by integrating morphodynamics and the habitat needs of species of interest or to ensure that aggregate water extraction is done in a manner and at sites that do not degrade freshwater ecosystems. Ecohydraulics also informs the maintenance or re-establishment of river connectivity through design of fish passage facilities. In summary, ecohydraulics has much to offer in the support of efforts to maintain and restore freshwater biodiversity. Doing so will require continued investment in fundamental and mission-oriented science, but also an emphasis on equipping practitioners with knowledge to implement actions that benefit freshwater biodiversity and people.

摘要: The freshwater blenny Salariopsis fluviatilis is fairly widespread across Mediterranean inland freshwaters but with an unusually patchy distribution. We investigated the species’ distribution patterns in Greece, its habitat, and the effects of anthropogenic pressures by providing an in-depth review of electrofishing sampling data, covering 717 river sites (14.4 ​% with the species present), plus bibliographical data for the first time from Greece. We found that the species is confined predominately to natural lotic and often small water bodies (such as coastal streams), usually with spatially restricted, low-density populations. Many suitable river stretches are not inhabited by this otherwise widespread fish, now documented in 46 river basins in Greece. We identified local extirpation in 7 basins and hypothesize that the species may have been more widespread in the past. We provide evidence that anthropogenic pressures such as artificial barriers (e.g., dams, road-crossing fords) severely limit movement, i.e., 77.7 ​% of the total sites with S. fluviatilis were located in proximity to artificial barriers. However, two inland populations appear to benefit from impounded reservoirs, which sustain high-density populations in connected inflow streams. The species is vulnerable to range declines due to further habitat degradation, drought effects, and fragmentation. A precautionary approach is required for assessing its current conservation status. Conservation measures, focusing on stream ecosystems, connectivity restoration, and reintroduction are proposed.

摘要: Dam construction and other anthropogenic disturbances are recognized to degrade lake habitat heterogeneity and consequently diminish fish biodiversity. To elucidate the changes in fish assemblages resulting from their synergistic interactions, we analyzed how fish community assembly was affected by habitat diversity (reservoir size) and anthropic disturbances (eutrophication and urbanization) in 47 subtropical reservoirs through both functional and phylogenetic dimensions. We found a functional and phylogenetic clustering gradient linked to reservoir area and anthropization, indicating a strong functional redundancy of the fish assemblages. Such a pattern is modulated by eutrophication that selects fish species able to survive under high nutrient and low oxygen environments, thus triggering the functional clustering of fish assemblages, but increasing functional insurance. Surprisingly, phylogenetic clustering was less sensitive than functional clustering to eutrophication and urbanization, due to the introduction of non-native species belonging to exotic lineages. In addition, urbanization also strongly affected fish community assembly by introducing non-native species with original trait combinations, thus reducing the functional and phylogenetic clustering of fish assemblages in most urban areas. Overall, this study demonstrates that fish assemblages are better insured against disturbances in large reservoirs than in smaller ones, but that the functional and phylogenetic structure of fish communities are largely influenced by non-native species.