Viruses play a crucial role in aquatic ecosystems by regulating microbial composition and impacting biogeochemical cycling. While the response of viral diversity to the trophic status has been preliminarily explored in lake ecosystems, there is limited integrated exploration of the biogeography of viruses, host associations, and the auxiliary metabolic genes (AMGs), particularly for plateau lakes. Therefore, this research investigated the viral biogeography, virus-host association, and AMGs in the surface waters of 11 lakes varying in trophic levels (eutrophic and oligo-mesotrophic) in the Yunnan-Guizhou plateau region of China. A total of 73,105 viral operational taxonomic units were obtained from 11 samples, with 84.8 % remaining unannotated at the family level, indicating a predominance of novel viruses within these lakes. The most abundant viral family was Kyanoviridae (24.4 %), recognized as a common cyanophage. The vast majority of cyanobacteria and several eukaryotic algae were predicted as hosts for the viruses, with a lytic lifestyle predominating the life strategy of these cyanophages, implying the potential influence of the virus on algae. The viral community structure significantly correlated with both trophic status and the bacterial community. The structure equation model analysis revealed chlorophyll a was the primary factor affecting viral communities. Moreover, numerous AMGs linked to carbon metabolism, phosphorus metabolism, sulfur metabolism, and photosynthesis were found in these lakes, some of which showed virus preference for the trophic statuses, suggesting a vital role of the virus in driving biogeochemical cycling in the lake crossing different nutrient levels. In addition, a restricted presence of viruses was found to infect humans or harbor antibiotic resistance genes in the lakes, suggesting a subtle yet potential link to human health. Overall, these findings offer insights into the response of viral communities to eutrophication and their potential role in biogeochemical cycling and controlling algal propagation.

Research about feeding ecology of fish is important to understand individual behavior and population development, which is also the basic to analyze trophic structure and function of aquatic ecosystems. Chaetrichthys stigmatias is one of the key species in the Haizhou Bay fisheries ecosystem, which has critical ecological niche within the food web. In this study, we collected samples through bottom trawl surveys during the fall of 2018 in the Haizhou Bay, and analyzed the feeding ecology of C. stigmatias based on both stomach content analysis and stable isotope technology. The results showed that the primary diet groups for C. stigmatias were Ophiuroidea and Shrimp, including Ophiothrix marenzelleri, Ophiopholis mirabilis, Ophiura sarsii, Penaeidae, and Alpheus japonicus. The range of δ13C values of C. stigmatias was from -19.39‰ to -15.74‰, with an average value of (-18.07±0.87)‰, which had no significant correlation with body length. The range of δ15N values was from 8.16‰ to 12.86‰, with an average value of (10.14±1.51)‰, which was positively correlated with body length. The trophic level of C. stigmatias showed a positive relationship with body length, with an average value of (3.74±0.34) and a range value of 3.32 to 4.20 among different size groups. The contribution rates of different prey groups varied significantly. Based on the structural equation modeling, we found that the feeding intensity of C. stigmatias was primally influenced by body length, sea bottom salinity, sea bottom temperature, and water depth, with a particularly signi-ficant positive correlation with body length. The combination of stable isotope technology and stomach content analysis methods could contribute to comprehensive understanding on the feeding ecology of C. stigmatias, providing essential data and foundation for research on trophic structures and resource conservation in the Haizhou Bay ecosystem.
对鱼类摄食生态开展研究是了解其生长发育、个体行为的重要途径,也是分析食物网结构和水生生态系统功能的关键。矛尾虾虎鱼是海州湾渔业生态系统中的主要鱼类之一,在营养结构研究中具有较大的生态价值。本研究基于2018年秋季海州湾底拖网调查采集的样本,结合胃含物分析方法和碳、氮稳定同位素技术,对海州湾矛尾虾虎鱼的摄食生态特性进行了分析。结果表明: 海州湾矛尾虾虎鱼主要摄食的饵料类群是蛇尾类和虾类,优势饵料生物是马氏刺蛇尾、紫蛇尾、萨氏真蛇尾、对虾科种类和日本鼓虾。矛尾虾虎鱼的δ13C值范围为-19.39‰～-15.74‰,平均值为(-18.07±0.87)‰,与体长无显著相关性;δ15N值范围为8.16‰～12.86‰,平均值为(10.14±1.51)‰,与体长呈显著正相关。各体长组矛尾虾虎鱼营养级范围为3.32～4.20,平均值为3.74±0.34,营养级与体长呈显著正相关,各类群饵料生物贡献率差异较大。通过结构方程模型分析发现,矛尾虾虎鱼的摄食强度主要受到体长、底层盐度、底层温度和水深的影响,尤其体长与摄食强度之间存在显著的正相关关系。结合稳定同位素和胃含物分析方法可以全面解析海州湾矛尾虾虎鱼的摄食生态,为海州湾营养结构研究及资源养护提供基础资料和科学依据。.

Understanding the interactions between fish gut microbiota and the aquatic environment is a key issue for understanding aquatic microorganisms. Environmental microorganisms enter fish intestines through feeding, and the amount of invasion varies due to different feeding habits. Traditional fish feeding habitat preferences are determined by fish morphology or behavior. However, little is known about how the feeding behavior of fish relative to the vertical structure in a shallow lake influences gut microbiota. In our study, we used nitrogen isotopes to measure the trophic levels of fish. Then high-throughput sequencing was used to describe the composition of environmental microbiota and fish gut microbiota, and FEAST (fast expectation-maximization for microbial source tracking) method was used to trace the source of fish gut microbiota. We investigated the microbial diversity of fish guts and their habitats in Lake Sanjiao and verified that the sediments indeed played an important role in the assembly of fish gut microbiota. Then, the FEAST analysis indicated that microbiota in water and sediments acted as the primary sources in half of the fish gut microbiota respectively. Furthermore, we classified the vertical habitat preferences using microbial data and significant differences in both composition and function of fish gut microbiota were observed between groups with distinct habitat preferences. The performance of supervised and unsupervised machine learning in classifying fish gut microbiota by habitat preferences actually exceeded classification by fish species taxonomy and fish trophic level. Finally, we described the stability of fish co-occurrence networks with different habitat preferences. Interestingly, the co-occurrence network seemed more stable in pelagic fish than in benthic fish. Our results show that the preferences of fish in the vertical structure of habitat was the main factor affecting their gut microbiota. We advocated the use of microbial interactions between fish gut and their surrounding environment to reflect fish preferences in vertical habitat structure. This approach not only offers a novel perspective for understanding the interactions between fish gut microbiota and environmental factors, but also provides new methods and ideas for studying fish habitat selection in aquatic ecosystems.

Microplastics (MPs) are widely found in the ocean and cause a serious risk to marine organisms. However, fewer studies have been conducted on benthic organisms. This study conducted a case study on the pollution characteristics of MPs on 16 marine benthic organisms in Haizhou Bay, and analyzed the effects of habitat, trophic level, and feeding mode on the MPs pollution characters. The results showed that MPs were detected in all 16 organisms with an average abundance of 8.84 ± 9.14 items/individual, which is in the middle-high level in the international scale. Among the detected MPs, the main material was cellophane. This study showed that benthic organisms can be used as indicator organisms for MPs pollution. MPs in organisms can be affected by their habitat, trophic level, and feeding mode. Comprehensive analysis of MPs in benthic organisms will contribute to fully understand the characterization and source resolution of MPs pollution.

Nanotechnology offers great opportunities for numerous sectors in society. One important challenge in sustainable nanotechnology is the potential of trophic transfer of nanomaterials (NMs), which may lead to unintentional impacts on environmental and human health. Here, we highlight the key advances that have been made in recent 15 years with respect to trophic transfer of heterogeneous NMs, including metal-based NMs, carbon-based NMs and nanoplastics, across various aquatic and terrestrial food chains. Particle number-based trophic transfer factors (TTFs), rather than the variable mass-based TTFs, capture the particle-specific transfer, for which NMs exhibit dynamic and complex biotransformation (e.g., dissolution, sulfidation, reduction, and corona formation). Trophic transfer of NMs has toxicological significance to predators at molecular (e.g., increased oxidative stress and modified metabolites), physiological (e.g., feeding inhibition) and population (e.g., reproduction inhibition) levels. However, linking NM exposure and toxicity remains a challenge, partly due to the dynamic biotransformation along the food chain. Although NMs have been used to increase crop yield in agriculture, they can exert detrimental impacts on crop yield and modify crop quality, depending on NMs type, exposure dose, and crop species, with unknown consequences to human health via crop consumption. Given this information, we describe the challenges and opportunities in understanding the significance of NMs trophic transfer to develop more sustainable, effective and safer nanotechnology.

Stable isotope technique is important for understanding the structure and function of soil food web, which is considered as a belowground black box. We reviewed typical application cases of stable isotope techniques in the research of soil food webs, including to determine food sources and feeding preferences of soil fauna by using isotopes, and to analyze the trophic structure of soil food webs through isotope fractionation effects during the process of feeding and nutrient sequestration by soil fauna. Additionally, stable isotope techniques could reveal the role of soil biota at different trophic levels within soil food web in ecosystem matter and energy flow, which favored to carry out accurate and efficient research on the contribution of soil food webs to soil carbon and nitrogen cycling process and the corresponding influence mechanism. We further put forward the limitations of current stable isotope techniques and the future development directions.
稳定同位素技术的发展为深入揭示地下黑箱-土壤食物网的结构和功能提供了重要的方法和手段。本文回顾了稳定同位素技术在土壤食物网研究中的应用,主要包括利用同位素确定土壤动物的食源和食性偏好;通过土壤动物取食与固持养分过程中的同位素分馏效应,分析土壤食物网的营养级结构;此外,稳定同位素技术还揭示了土壤食物网各营养级土壤生物在土壤生态系统物质能量流动中的作用,有助于准确高效地开展土壤食物网在土壤碳氮循环过程中的贡献及作用机理研究。本文同时指出了目前稳定同位素技术的局限性,展望了未来重点发展的方向。.

Large parts of the Earth are experiencing environmental change caused by alien plant invasions, rising atmospheric concentration of carbon dioxide (CO2 ), and nutrient enrichments. Elevated CO2 and nutrient concentrations can separately favour growth of invasive plants over that of natives but how herbivory may modulate the magnitude and direction of net responses by the two groups of plants to simultaneous CO2 and nutrient enrichments remains unknown. In line with the enemy release hypothesis, invasive plant species should reallocate metabolites from costly anti-herbivore defences into greater growth following escape from intense herbivory in the native range. Therefore, invasive plants should have greater growth than native plants under simultaneous CO2 and nutrient enrichments in the absence of herbivory. To test this prediction, we grew nine congeneric pairs of invasive and native plant species that naturally co-occurred in grasslands in China under two levels each of nutrient enrichment (low-nutrient vs. high-nutrient), herbivory (with herbivory vs. without herbivory) and under ambient (412.9 ± 0.6 ppm) and elevated (790.1 ± 6.2 ppm) levels of CO2 concentrations in open top chambers in a common garden. Elevated CO2 and nutrient enrichment separately increased total plant biomass, while herbivory reduced it regardless of the plant invasive status. High-nutrient treatment caused the plants to allocate a significantly lower proportion of total biomass to roots, while herbivory induced an opposite pattern. Herbivory suppressed total biomass production more strongly in native plants than invasive plants. The plants exhibited significant interspecific and intergeneric variation in their responses to the various treatment combinations. Overall, these results suggest that elevated CO2 and nutrients and herbivory may separately, rather than synergistically, impact productivity of the invasive and co-occurring native plant species in our study system. Moreover, interspecific variation in resource-use strategies was more important than invasive status in determining plant responses to the various treatment combinations.

A fundamental question in ecology is which species will prevail over others amid changes in both environmental mean conditions and their variability. Although the widely accepted fluctuating resource hypothesis predicts that increases in mean resource availability and variability therein will promote nonnative plant invasion, it remains unclear to what extent these effects might be mediated by soil microbes. We grew eight invasive nonnative plant species as target plants in pot-mesocosms planted with five different synthetic native communities as competitors, and assigned them to eight combinations of two nutrient-fluctuation (constant vs. pulsed), two nutrient-availability (low vs. high) and two soil-microbe (living vs. sterilized) treatments. We found that when plants grew in sterilized soil, nutrient fluctuation promoted the dominance of nonnative plants under overall low nutrient availability, whereas the nutrient fluctuation had minimal effect under high nutrient availability. In contrast, when plants grew in living soil, nutrient fluctuation promoted the dominance of nonnative plants under high nutrient availability rather than under low nutrient availability. Analysis of the soil microbial community suggests that this might reflect that nutrient fluctuation strongly increased the relative abundance of the most dominant pathogenic fungal family or genus under high nutrient availability, while decreasing it under low nutrient availability. Our findings are the first to indicate that besides its direct effect, environmental variability could also indirectly affect plant invasion via changes in soil microbial communities.

Certain polybrominated diphenyl ethers (PBDEs) have been banned for years, however, they still possess the potential to harm marine cetaceans. In this study, 56 East Asian finless porpoises (EAFPs) collected from three locations of the East China Sea between 2009 and 2011, were analyzed to determine the presence of typical PBDE congeners. Among all the samples, BDE47 was the main congener, constituting ∼48.3 % of the ΣPBDEs. Significant variations (p < 0.01) in PBDE abundance were observed among different regions (Pingtan: 172.8 ng/g, Lvsi: 61.2 ng/g and Ningbo: 32.9 ng/g). In addition, there was a significant positive correlation between PBDE abundance and male body length. The general ΣPBDEs concentration of this population was lower compared to other populations and cetaceans. Although combined risk assessments indicated a low risk to porpoise health, long-term surveillance is essential as PBDEs are not completely banned.

Bromophenols (BrPs) are artificial precursors of some flame retardants and important substances with natural marine- or ocean-like flavors. This study studied the temporal variations and spatial distributions of BrPs in 150 mollusk samples (12 species) collected from 9 cities around the Bohai Sea from 2009 to 2019. Only 3 B.P. among the tested 19 congeners, 4-monobromophenol (4-mBrP), 2,4-dibromophenol (2,4-diBrP), and 2,4,6-tribromophenol (2,4,6-triBrP), were extensively detected with the detection frequency of 98.7 %, 86.7 %, and 98.0 %. The median concentration of 2,4,6-triBrP was 4.27 ng/g dw, followed by 4-mBrP (1.89 ng/g dw) and 2,4-diBrP (0.625 ng/g dw). The concentration of 3 detectable congeners, ∑3BrPs\' ranged from 0.152 to 703 ng/g dw with a median value of 8.08 ng/g dw. The highest concentrations of ∑3BrPs and 2,4,6-triBrP all occurred in Rapana venosa (49.2 and 45.1 ng/g dw) which belongs to Muricidae (2009 to 2019) that was at a relatively higher trophic level among the tested mollusks. The concentration of BrPs in Gastropoda is much higher than that in Bivalvia. The median concentrations of 2,4-diBrP, 2,4,6-triBrP, and ∑3BrPs in Gastropoda and Bivalvia from Shandong Province were higher than those in other administrative divisions at the provincial level because of the large volume of BrP production and brominated flame retardants. Temporal variations in Gastropoda and Bivalvia from Weihai showed that concentrations of ∑3BrPs, 2,4,6-triBrP, 4-mBrP, and 2,4-diBrP declined slowly from 2009 to 2019. Our results provide a systematic insight into the environmental occurrence and fate of BrPs in the Bohai Sea.