Abstract:

Located at the mouth of the Yangtze River estuary， Shanghai is one of China's major commercial ports and ornamental fish trade hubs， boasting a well-developed aquaculture industry. Therefore， a systematic investigation into the species， distribution， and invasion risks of alien fish introduced to Shanghai's natural water bodies is warranted. In this study， environmental DNA metabarcoding （eDNA Metabarcoding） was employed to survey alien fish at 82 sampling sites in Shanghai during spring and autumn， detecting a total of seven alien fish species. The identified alien fish was assessed for invasion risk using the Aquatic species invasiveness screening kit （AS-ISK）， and their potential habitat suitability was predicted using the Maxent model combined with climate data and distribution records. The results indicated that the mosquitofish （Gambusia affinis）， largemouth bass （Micropterus salmoides）， and channel catfish （Ictalurus punctatus） exhibited high invasion risks （BRA > 42.5） in the AS-ISK assessment， necessitating prioritized monitoring. In contrast， the paddlefish （Polyodon spathula） and mrigal carp （Cirrhinus mrigala） initially showed low invasion risks （BRA < 40）. However， when accounting for future climate change， the invasion risk of mrigal carp escalated from low to high （BRA + CCA > 47.5）. The Maxent model predicted that areas near the lower reaches of the Huangpu River estuary generally had high habitat suitability for the detected alien fish， while mrigal carp showed higher suitability in Dianshan Lake in western Shanghai. Additionally， Nile tilapia（Oreochromis niloticus） and marble goby（Oxyeleotris marmorata） were detected in the survey. However， since both species are intolerant to low temperatures and cannot overwinter in Shanghai， they were excluded from the invasion risk assessment and habitat suitability predictions. Timely identification of the species and distribution of alien fish in natural water bodies is crucial for preventing biological invasions， highlighting the need for focused monitoring of high-risk species and regions with high habitat suitability for alien species. Environmental DNA technology provides a cost-effective and efficient tool for long-term alien fish monitoring.

Abstract:

To meet the need for rapid detection of Alexandrium tamarense in field environments， it is imperative to develop a real-time method with high sensitivity and specificity. In this study， a visual method referred to as recombinase polymerase amplification coupled with lateral flow dipstick （RPA-LFD） was developed for rapid detection. The primers for RPA and the detection probe for LFD were designed to specifically target the internal transcribed spacer of A. tamarense by molecular cloning and multiple alignments of the related sequences. The results showed that the successful amplification for RPA could be achieved at optimal conditions of 42 °C and 15 min， and enough products were visually detected by the naked eye through an LFD after an automatic chromatography for 3 min at room temperature. The research indicated that the RPA-LFD exhibited exceptional specificity for A. tamarense and displayed no cross-reactivity with other common algae. The detection limits were as low as 1 copies/μL for plasmid DNA and 1 cells/L for intact cells， representing a 100-fold increase in sensitivity compared to conventional PCR methods. In conclusion， the developed RPA-LFD assay enables rapid detection of A. tamarense-induced HABs while enhancing invasive species screening efficiency at ports.

Abstract:

Pistia stratiotes L. （water lettuce）， as a highly detrimental invasive plant species in China's freshwater ecosystems， has posed significant threats to aquatic ecological security through its rapid proliferation. To enable early monitoring and control of this species， this study developed a highly sensitive and specific detection system based on environmental DNA （eDNA） technology. By integrating k-mer indexing strategies with chloroplast genome alignment analysis， we designed four sets of species-specific multiplex PCR primers （PS_7， PS_8， PS_9， PS_10）. Experimental validation demonstrated that: （1） All individual primers and their combinations effectively amplified target DNA from tissue samples， aquaculture water， and natural water samples； （2） The detection limits reached 0.69×10^-2 ng/μL for individual primers PS_7 and PS_10， 0.34×10^-1 ng/μL for PS_8， and 0.17 ng/μL for PS_9. The multiplex PCR system achieved a detection limit of 1.1×10^-5 ng/μL， representing approximately a 625-fold improvement in sensitivity compared to the best single primer （P<0.01）； （3） Specificity tests confirmed no cross-reactivity with closely related species such as Spirodela polyrhiza. The entire detection process can be completed within 3 hours. This established detection system provides reliable technical support for early warning and monitoring of Pistia stratiotes invasions， while serving as a practical model for developing rapid eDNA-based detection methods for aquatic invasive plants.

Abstract:

As climate change，international trade，and human activities increasingly disrupt traditional geographic barriers in the oceans，non-indigenous species（NIS）have successfully established themselves outside their native ranges. Outbreaks of NIS can pose significant threats to local ecosystems and economies，making them a critical issue for marine biodiversity and biosecurity. Biological invasions in marine habitats differ significantly from those on land or in freshwater. Detection and identification of NIS in marine habitats is particularly challenging due to difficulties in sampling，morphological identification，and visualization in the early stages of outbreaks. Environmental DNA（eDNA）approaches have emerged as reliable and cost-effective methods for both qualitative and quantitative detection of marine NIS，particularly in the introductory phase. In this review，we summarize recent applications and advances in eDNA-based detection of marine NIS. We emphasize that innovations in eDNA sampling equipment，improvements in detection methods，and further refinement of the reference genomic database for marine species are crucial for the future development of this field.

Abstract:

The rapid expansion of global trade and transportation networks has escalated biological invasions， posing critical threats to aquatic ecosystem integrity and incurring substantial economic costs. Compared to terrestrial invasions， research on aquatic invasions emerged more recently， with limited systematic analysis of their mechanisms and drivers. This review synthesizes advances from the past decade to outline key mechanisms-including competitive advantage， niche occupation， interspecific interactions， chemical invasion， and enemy release-underlying aquatic invasions. Critical drivers are examined， encompassing environmental shifts （e.g.， climate change， hydrological alterations， pollution） and anthropogenic disturbances. Future priorities emphasize mechanistic validation， predictive modeling frameworks， and integrated management strategies. This review enhances understanding of aquatic invasion dynamics and provides actionable insights for ecosystem resilience and evidence-based governance.

Abstract:

Through field sampling， this study investigated the species composition and distribution of alien fishes in Guangxi's inland waters. The results indicate: （1） Species composition and sources: A total of 23 alien fish species， belonging to 7 orders， 13 families， and 20 genera， were recorded. Perciformes （9 species） and Cypriniformes （5 species） are the dominant orders. Aquaculture introduction is the primary pathway， accounting for 82.61% of the species. （2） Status and distribution: Coptodon zillii and Oreochromis niloticus have become the dominant species， distributed across nearly all survey sites. Thirteen species are considered invasive， and four are in the establishment stage. Spatially， a geographical pattern of "C. zillii in the north， O. niloticus in the south" originates from the stronger adaptability to low temperatures and higher fecundity of Coptodon zillii； a mainstream-tributary disparity pattern is also evident， where the species number in mainstreams such as the Hongshui River （16 species） is far higher than in upstream tributaries. The lentic environments created by hydropower dam construction have significantly altered the habitats of native fish， providing 'ecological niche opportunities' for the expansion of alien species adapted to such conditions. （3） Control strategies: An integrated control framework is proposed， comprising four key components: source prevention， monitoring and early warning， control and eradication， and public participation. This research provides a scientific basis for policymaking and reference for ensuring aquatic ecological security and biodiversity conservation in Guangxi and southern China.

Abstract:

This study evaluates the ecological risks associated with non-native Testudinata species in Chinese markets and develops science-based management strategies. Utilizing comprehensive literature review and quantitative data analysis， we investigated the historical introduction patterns， taxonomic diversity， geographical distribution， and commercial trade dynamics of non-native Testudinata species in China. Ecological risk assessment was conducted to analyze their potential impacts on native species and ecosystems. The results revealed that while China hosts 40 native Testudinata species （belonging to 6 families and 22 genera）， non-native species dominate the market， accounting for 75% of traded individuals （three times the proportion of native species）， with the highest concentrations in South and East China. The invasion of non-native species has led to habitat compression for native Testudinata， intensified farming practices， and increased risks of biological invasions and disease transmission. This study highlights the substantial market scale and ecological threats posed by non-native Testudinata species in China， emphasizing the need for a differentiated management framework. The findings provide critical insights for establishing regulations on Testudinata introductions， optimizing invasive species control strategies， and promoting sustainable development of the Testudinata industry.

Abstract:

Global warming has facilitated the expansion of the invasive cyanobacterium Raphidiopsis raciborskii to higher latitudes， while current studies on bloom control methods for this species remains limited. This study evaluated the algicidal effects of two amino acid analogs， L-3，4-dihydroxyphenylalanine （L-DOPA） and homoarginine （Har）， on R. raciborskii and investigated their physiological impacts. Results showed that both compounds significantly induced reactive oxygen species （ROS） accumulation， with L-DOPA exhibiting stronger ROS stimulation than Har. Both analogs damaged the photosynthetic system: L-DOPA impaired the photosystem reaction centers， electron transport chain， and chlorophyll a （Chl.a）， while significantly reducing phycobiliprotein （PBP） content but increasing the proportions of allophycocyanin （APC） and phycoerythrin （PE）. L-DOPA treatment caused severe filament fragmentation （average length reduced to 9.70% of the control） and extensive cellular damage. In contrast， Har damaged the photosystem reaction centers and electron transport chain but promoted PBP synthesis and PE proportion， resulting in moderate filament breakage （22.33% of the control） and significant extracellular polymeric substance （EPS） secretion. This study demonstrates that both Har and L-DOPA effectively inhibit R. raciborskii， with L-DOPA exhibiting stronger algicidal activity， indicating that the two amino acid analogs exhibit distinct algicidal mechanisms. Our findings provide fundamental data for developing novel cyanobacterial bloom control technologies.

Abstract:

This study constructs a comprehensive evaluation system to assess the impact of aquatic invasive species from three dimensions: economic， ecological， and social impacts. First， a questionnaire was distributed using stratified sampling to collect expert assessments on the relative importance of influencing factors. Analytic hierarchy process （AHP） was applied to determine the weights. The results revealed that the economic impact （0.72） was considered more significant than ecological （0.17） and social impacts （0.11）. Top five influencing factors were direct economic losses （0.47）， niche occupation （0.11）， control costs （0.09）， eradication expenses （0.08） and public awareness （0.067）. Next， the impact of Pomacea canaliculata invasion in Shanghai was scored across districts. Areas with scores exceeding percentile 50 included Chongming （P₉₉）， Songjiang （P₆₈）， Jinshan （P₆₄）， Pudong （P₆₁）， and Qingpu （P₅₃）. In conclusion， a district-diversified and level-specific strategy is proposed for preventing Pomacea canaliculata invasion in Shanghai， guided by the principles of prioritizing economic impact， protecting ecologically sensitive areas， and incorporating public participation.

Abstract:

The invasion of aquatic organisms has become one of the major threats to China's ecological security. Aquatic biological invasion has strong concealment and harmfulness， which not only easily leads to the destruction and degradation of aquatic ecosystem， but also brings huge economic losses to China. From the perspective of legal regulation of aquatic biological invasion， this paper systematically analyzes and combs the legal characteristics of aquatic biological invasion prevention and control in different periods in China， and divides its legal development process into four stages: initial stage， transition stage， steady progress stage and high-quality development stage. At present， the construction of legal norms for the prevention and control of aquatic biological invasion in China has made great progress， and the prevention and control legal system with unique Chinese characteristics has been basically completed， which has laid a solid legal foundation for the prevention and control of aquatic biological invasion. However， it should be pointed out that the construction of the legal system is still in the development stage， and the problems such as the lack of special unified legislation， the insufficient realization of the value of legal order， the imperfect department coordination system and the insufficient supply of accountability and relief systems are still prominent. These deficiencies greatly limit the effectiveness of the prevention and control of aquatic biological invasion in China， and constitute the main challenge of the construction of prevention and control laws and regulations. In view of the above shortcomings， this paper proposes measures to optimize the evaluation and approval system， build a coordination management institution， strengthen the construction of government governance system and ensure the pluralistic co-governance pattern by legislation under the premise of building a special unified legislation， so as to realize the improvement of the legal system for the prevention and control of aquatic biological invasion in China. This study is expected to provide some reference for the protection of aquatic ecosystem and biological invasion control in China.

Abstract:

The study presented an MaxEnt-based assessment of current and future habitat suitability for invasive redbelly tilapia （Coptodon zillii） in China under changing climatic conditions. This freshwater species， native to West， East， and North Africa and parts of the Middle East， was modeled using occurrence records and eight environmental variables. The results showed that the final model demonstrated strong predictive performance （AUC=0.84， TSS=0.6）， identifying four dominant variables [mean temperature of coldest quarter （Bio11）， annual precipitation （Bio12）， temperature annual range （Bio7） and elevation]. Suitable habitats for both current and future environment were concentrated in southern provinces of China. Under three future climate scenarios （SSP1， SSP2， SSP5）， divergent trends were revealed: substantial habitat expansion under SSP5-8.5， moderate habitat increase under SSP2-4.5， and marked habitat contraction under SSP1-2.6. These findings align with global climate model projections， demonstrating that stringent emission controls （SSP1-2.6） can significantly reduce invasive habitat suitability. The study highlights climate policy as a potential tool for managing aquatic invasions in China’s freshwater ecosystems.

Abstract:

In order to assess the ecological risks of the toxic red tide alga Alexandrium tamarense to juvenile thick-shell mussels （Mytilus coruscus）， juvenile mussels with an average shell length of （18.40±2.04） mm were selected， and the mortalities of juvenile M. coruscus over 12 days were calculated after continuous exposure to the culture and filtrate of A. tamarense， tissue antioxidant enzymes and metabolism-related enzyme activities were also measured. The mortalities of juvenile mussels were recorded at 48 hours intervals in the control， whole-cell and filtrate groups， and the activities of superoxide dismutase （SOD）， catalase （CAT）， glutamine-phosphatase （GPT）， alkaline phosphatase （AKP）， and acetylcholinesterase （AChE） of the individuals on 4^th， 8^th and 12^th days after exposure were analyzed. The results showed that the corrected cumulative mortality of juvenile mussels in the whole-cell and filtrate groups on the 12^th day was 33.73% and 15.66%， respectively. Enzyme activity trends varied among the groups. The activities of SOD， CAT， AKP and AChE in the whole-cell group showed an overall increasing trend， and the GPT activity showed a decreasing and then increasing phenomenon. In the filtrate group， AKP activity remained relatively stable. After 8 days of continuous exposure， SOD and AChE activities showed a decreasing trend， while GPT and CAT activities increased. By day 12^th， SOD and CAT activities had decreased， whereas GPT and AChE activities had increased. On the 12^th day， the activities of five enzymes in the whole-cell group were significantly higher than those in the control group （P<0.05）. The principal component analysis （PCA） showed that the physiological indicators were positively correlated， and the integrated biomarker response （IBR） index showed that the IBR value of the whole-cell group differed from the control group， indicating that the whole-cell culture of A. tamarense has a high toxic effect on juvenile mussels. The results indicated that both the culture and filtrate of A. tamarense above the baseline density of red tide would stress the survival of juvenile M. coruscus， inducing oxidative stress in mussels， and suppressing the metabolism function of juvenile mussels at the early stage of exposure. This study provides a reference for conducting scientific culture of M. coruscus during toxic red tide outbreaks.

Abstract:

The invasion of Pomacea canaliculata poses a significant threat to the survival of native species and disrupts the functioning of native ecosystems. Daphnia magna， known for its rapid reproduction， malleable body shape， and ease of observation， is frequently used as a model organism in environmental risk assessment studies. This study aimed to explore the effects of the invasion of P. canaliculata on the life history， morphology， antioxidant performance， and gut microbiota of D. magna by establishing four experimental groups: no-snail control group （Ctr）， native snail Cipangopaludina chinensis group （CC）， limited-bacterial P. canaliculata group （LBPC） and P. canaliculata group （PC）. The results showed that the invasion of P. canaliculata promoted the growth， and reproduction of D. magna， and affected its life cycle. D. magna in the PC group had significantly reduced body length and tail spine length （P<0.05）， while the population size and reproductive rate were significantly increased （P<0.05）. Additionally， the activity of antioxidant enzymes was significantly enhanced （P<0.05）. Additionally， the β-diversity of intestinal microbiota in D. magna was significantly altered in the PC group （P<0.05）， with predicted microbial pathways shifting toward anti-inflammatory functions and enhanced metabolic capacity. However， inhibiting pathogenic bacteria in the intestinal tract of P. canaliculata alleviated its indirect stress effects on the growth， reproduction， and intestinal microbiota composition of D. magna. These findings indicate that P. canaliculata exerts significant indirect pressure through non-predatory interactions， affecting the physiological characteristics and gut microbial community of D. magna， potentially posing a risk to native freshwater ecosystems， which may be partly attributed to changes in its gut microbiota. This study enriches the understanding of the interspecific interaction mechanisms between P. canaliculata and native zooplankton， providing important insights into the life history strategies of P. canaliculata.

Abstract:

To explore the adaptability of the invasive aquatic plant Pistia stratiotes L. to climate and habitat in different regions， and to provide a theoretical basis for controlling and preventing its further spread. MAXENT was employed to predict the potential suitable habitat of P. stratiotes in China. Cold tolerance， light adaptability， and nutrient deficiency experiments were conducted on P. stratiotes populations from Hainan， Hunan， and Jiangsu to evaluate their physiological and ecological responses under various climatic and habitat conditions. The minimum temperature of the coldest month is the primary climatic factor influencing the distribution of P. stratiotes. Cold-tolerance experiments demonstrated that， following continuous exposure to 5.0 °C for 48 h， the samples from Hainan exhibited significant frostbite symptoms and could not resume growth under normal temperature， whereas samples from Jiangsu recovered. Peroxidase activity assays indicated that P. stratiotes from Jiangsu responded more rapidly to low-temperature stress by increasing peroxidase activity. After one month of shading， P. stratiotes from all three regions showed reduced growth rate， lower chlorophyll content， and heightened antioxidant enzyme activity， with no significant differences among the areas， indicating that P. stratiotes prefers light and is sensitive to shading. Nutrient deficiency experiments revealed that nitrogen and phosphorus deprivation significantly suppressed fresh weight， leaf number， width， and ramet production. However， there were no significant differences in growth inhibition between nitrogen and phosphorus deficiency. Temperature， light， nitrogen and phosphorus nutrient are the primary factors affecting plant growth and distribution.Among them，temperature plays a particularly crucial role in the invasion， spread， and reproduction of P. stratiotes. Notably， populations in northern regions showed significantly stronger cold tolerance than those in the southern areas， suggesting that P. stratiotes has broadened its ecological niche during its invasion in China and developed an adaptation to low temperatures. Without proper preventive measures， P. stratiotes may continue to expand into more northern areas in China.

Abstract:

Based on the water environmental pollution issues caused by aquaculture wastewater discharge in the Yangtze River Delta region， this study conducted a comprehensive survey on the pollution characteristics of aquaculture pond wastewater in the Yangtze River Delta Ecological Green Integrated Development Demonstration Zone （Wujiang District， Qingpu District， Jiashan County）， and evaluated the removal effects of the "three ponds and two dams" wastewater treatment system on the main pollutants， including total nitrogen （TN）， total phosphorus （TP）， and permanganate index （COD_Mn）. The results showed that the overall pollution level of aquaculture wastewater in the demonstration zone was moderate， but there were significant differences in pollutant concentrations in the aquaculture wastewater of different areas， generally showing a phenomenon of Jiashan County > Wujiang District > Qingpu District. In addition， the pollution characteristics of different species aquaculture wastewater also showed significant differences. The pollutant concentrations in the aquaculture wastewater of reptiles were the highest， with TN and COD_Mn as representative pollutants， while those of crabs were the lowest， with only partial COD_Mn exceeding the standard. The "three ponds and two dams" process had the highest removal rate for TN， with sedimentation ponds being particularly effective. Followed by COD_Mn， with sedimentation ponds and ecological ponds showing better removal effects， while the lowest removal rate for TP. Based on the above pollution characteristics of aquaculture wastewater and the pollutant removal efficiency of the "three ponds and two dams" process， the following improvements to the wastewater treatment measures are proposed: For reptiles， it is recommended to increase the volume of sedimentation ponds and ecological ponds in the "three ponds and two dams" process to specifically improve the removal efficiency of TN and COD_Mn； for fish and shrimp aquaculture wastewater with lower pollutant concentrations but greater fluctuations， maintain the existing process to ensure the standard discharge of pollutants； for crab aquaculture wastewater that occasionally exceeds the standard for COD_Mn， it is recommended to adopt a more economical sedimentation pond + filtering dam "one pond and one dam" treatment process， focusing on reducing the concentration of COD_Mn. The implementation of the above strategies is expected to promote the transformation of the aquaculture industry in the Yangtze River Delta demonstration zone towards green development and promote the continuous optimization of water environmental quality.

Abstract:

Water quality ponds plays a pivotal role in the pond culture of Chinese Mitten Crab （Eriocheir sinensis）， influencing not only the yield and quality of the crabs but also the ecological health of the pond water and the compliance of discharged tail water with environmental standards. In this study， five representative adult Chinese mitten crab culture bases on Chongming Island were selected as sampling sites. The research systematically investigated and evaluated the changes in pond water quality throughout the crab culture period. The water quality parameters analyzed included dissolved reactive phosphorus （SRP）， total phosphorus （TP）， ammonia nitrogen （NH₄⁺-N）， nitrate nitrogen （NO₃^--N）， nitrite nitrogen （NO₂^--N）， total nitrogen （TN）， permanganate index （COD_Mn）， suspended particulate matter （SS）， Chlorophyll a （Chl.a）， among others. The results showed that the average concentrations of SRP and TP in the water of adult Chinese mitten crab culture ponds on Chongming Island ranged from 0.091 to 0.300， and from 0.235 to 0.449 mg/L， respectively， exhibiting fluctuations over the culture period. The average concentration of NH₄⁺-N was higher in April （3.82 mg/L）， but the NH₄⁺-N concentrations were lower in the middle and late stages of culture （< 2 mg/L）. The average concentration of TN was relatively high in April and May （7.04 and 6.19 mg/L， respectively）， the TN concentration in some ponds was also relatively high in September and October， but the TN concentrations were relatively low in the middle stage of culture （< 3 mg/L）. As the culture period progressed， the average concentration of COD_Mn initially decreased， reaching lower levels from April to September， before subsequently increasing again. The average concentration of SS fluctuated between 159 and 331 mg/L when the culture time prolonged. After June， the average concentration of Chl.a gradually increased and the maximum value was obtained in October. There was a significant correlation among TP， SRP， NH₄⁺-N， NO₂^--N and TN in the water of adult Chinese mitten crab culture ponds on Chongming Island， and COD_Mn was significantly positively correlated with TN and Chl.a. However， Chl.a was only significantly positively correlated with COD_Mn， and SS was only significantly positively correlated with NO₂^--N. For the adult Chinese mitten crab culture ponds on Chongming Island， the risk of cyanobacterial bloom was high. Compared to the Shanghai Aquaculture Tailwater Discharge Standards， the primary pollutant exceeded the limit was SS， while NH₄⁺-N and TN only surpassed the standard during the early stages of the culture period （from March to May）. To sum up， in the adult Chinese mitten crab pond on Chongming Island， the average concentrations of NH₄⁺-N significantly declined during the middle and late stages of the culture period. Meanwhile， TN levels decreased notably in the mid-stage. As for COD_Mn， its average concentration initially decreased and then increased again， with lower average concentrations observed from April to September. COD_Mn and TN exhibited a significant positive correlation， while SS and NO₂^--N also showed a strong positive relationship. According to the pollutant discharge standards for aquaculture tailwater， SS emerged as the primary pollutant in Chongming Eriocheir sinensis culture ponds. Consequently， sedimentation treatment of tailwater is essential to ensure compliance with discharge standards before its release into receiving water bodies.

Abstract:

The characteristics of periphytic diatoms serve as effective indicators of changes in aquatic environments. However， research on the characteristics of periphytic diatom communities and their associated environmental factors in large urban river networks remains limited. Our study focuses on the urban river network of Shanghai City， selecting 16 medium and small rivers to investigate periphytic diatoms by using artificial substrates. The Trophic State Index （TSI） method was employed to comprehensively assess water quality. The characteristics of the periphytic diatoms communities were analyzed， and the threshold response of these communities to soluble nitrogen and phosphorus nutrients was quantified.Our results indicate that， with the exception of two sites in Shujiawan River， Baoshan District， most locations are eutrophic. The main genera with a relative abundance exceeding 10% include Navicula， Ulnaria， Nitzschia， Melosira， and Gomphonema. A total of 28 species with relative abundances greater than 1% were identified， with Melosira varians being the most dominant. Redundancy analysis （RDA） revealed that the primary factors influencing differences in periphytic diatom communities are dissolved total nitrogen （DTN）， dissolved total phosphorus （DTP）， ammonia nitrogen （NH₄⁺-N）， silica （SiO₂）， and chemical oxygen demand （COD_Mn）. Furthermore， threshold indicator taxa analysis （TITAN） indicated that the periphytic diatom communities undergo significant changes when the thresholds of DTN and DTP are reached.The positive response threshold for DTN is 2.26 mg/L， while the thresholds for DTP are 0.12 mg/L （positive response） and 0.16 mg/L （negative response）. Fourteen species exhibited a positive response to DTN， with Gomphonema angustatum showing the highest threshold at 3.30 mg/L. Fifteen indicator species responded positively to DTP， with Gomphonema acuminatum and Gomphonema gracile both displaying a threshold of 0.24 mg/L. Only two species showed negative responses: Gomphonella olivacea （threshold 0.14 mg/L） and Navicula cryptotenella （threshold 0.17 mg/L）， while Nitzschia palea was the most frequently observed species， occurring 31 times.The results demonstrate that key water chemical parameters in small and medium rivers of Shanghai significantly influence the structure of diatom communities. Species such as Gomphonema gracile can serve as bioindicators for dissolved total nitrogen （DTN） and dissolved total phosphorus （DTP） levels in water bodies. This study provides foundational data and technical support for ecological monitoring and scientific management of Shanghai's river network.

Abstract:

To explore the species composition and diversity characteristics of the existing fish in the middle reaches of the Sancha River， nine sampling sites were set up in the water area of the Qianzhong Water Control Project in the middle reaches of the Sancha River from the dry season and the flood season in 2022 and 2023. Three surveys were conducted on fish resources， and the current status of fish resources and species diversity in the water area were analyzed. The results showed that a total of 30 fish species were surveyed in the middle reaches of the Sancha River， belonging to 3 orders， 6 families， and 26 genera. Cypriniformes were the most abundant with 23 species， accounting for 76.67% of the total. There were 7 protected fish species and 2 exotic species. The dominant species were Hemiculter leucisculus， Aristichthys nobilis， Spinibarbus sinensis， and Carassius auratus. The fish diversity indices were Margalef's species richness index （D） at 3.96， Shannon-Wiener diversity index （H'） at 1.93， Pielou's evenness index （J′） at 0.57， and Simpson's dominance index （C） at 0.75. The β-diversity indices analysis showed that the β_c and β_r for the reservoir area and downstream water area of the Qianzhong Water Control Project Area were 8.0 and 15.8， respectively. The Jaccard similarity index （JSI） between the reservoir and downstream water areas was 0.47， indicating a moderate dissimilarity. The study suggests that there is a significant habitat difference between the reservoir area and downstream water area， with a certain differentiation in fish species. This study provides fundamental survey data for the conservation of fish diversity and scientific management in the Qianzhong Water Control Project Area.

Abstract:

In this study， we setted 12 sampling sites to explore the characteristics of plankton functional groups and its relation to enviromental factors in Bosten Lake. The main physical and chemical factors of water quality were analyzed， and the community structure of plankton in Bosten Lake， including species compositon， abundance and index of biological diversity were investigated. The results showed that water temperature， NH₃-N， total phosphorus and Chl.a in summer were extremely significantly higher than in spring， COD and electrical conductivity in summer were extremely significantly lower than in spring（P<0.01）. A total of 106 phytoplankton species and 50 zooplankton species were identified. Bacillariophyta was the highest number of phytoplankton（41）， followed by Chlorophyta（31）， Cyanophyta（27）， Pyrrophyta（3）， Cryptophyta（2）， Chrysophyta（2）. Rotifera was the highest number of zooplankton（20）， followed by Cladocera（17）， Copepoda（8）， Protozoa（5）. There were 5 dominant species of phytoplankton and 4 dominant species of zooplankton in summer， 3 dominant species of phytoplankton and 2 dominant species of zooplankton in spring. It was obvious change of dominant species of plankton in different seasons. The absolute dominant species of phytoplankton were Synedra sp.（Y=0.58）， Planktolyngbya subtilis（Y=0.15） and the absolute dominant species of zootoplankton were Polyarthra trigla（Y=0.32）， Keratella cochlearis（Y=0.18）， Anuraeopsis fissa（Y=0.14）. The absolute dominant species of phytoplankton was Dinobryon sp.（Y=0.75） and the absolute dominant species of zootoplankton were Bosmina longirostris（Y=0.48）， Polyphemus pediculus（Y=0.17） in spring. In summer， the average density（21.80×10⁶ cells/L） and average biomass （3.05mg/L） of phytoplankton were significantly higher than spring（0.023×10⁶ cells/L， 0.04 mg/L） （P<0.01）. The average density of zooplankton（105.75 ind./L） in summer was higher than spring（50.44 ind./L）， but the average biomass of zooplankton（0.87 mg/L） was higher than summer（0.16 mg/L）（P>0.05）. The average values of phytoplankton diversity indices of Shannon-wiener（H'）， Margalef（D） and Pielou（J） were 1.94， 0.45， 0.55 in summer and 1.35， 0.48， 0.46 in spring . The average values of zooplankton diversity indices of H'， D and J were 1.94， 0.45， 0.55 in summer and 1.35， 0.48， 0.46 in spring. In summer， the average of zooplankton diversity indices were significantly higher than spring （P<0.01）. There were no significant differences of phytoplankton diversity indices between summer and spring（P>0.05）. Water temperature plays an important role in the growth of phytoplankton， chl.a was an important factor affecting community structure of zooplankton in Bosten Lake. This study provides basic data and theoretical basis for the conservation of aquatic ecosystems and A. laticeps in the Bosten Lake.

Abstract:

By the environmental DNA （eDNA） technique and physicochemical parameter analyses， the spatial distribution characteristics of biological community structure， habitat elements and pollutants in the surface sediments of Hangzhou Bay and their impacts on biodiversity were systematically analysed. A total of 53 phyla were identified， with Metazoa dominating （42.55%）， notably the key species Portunus trituberculatus （20.84%）， indicating strong keystone species-driven community assembly. Biodiversity exhibited distinct spatial gradients: species richness indices （Observed species: 513-3 169； Chao1: 777.33-4 185.46） decreased southward， while evenness （Pielou J: 0.05-0.79） and diversity （Shannon: 0.31-6.01） showed a north-high， central-low， and south-moderate pattern. The spatial differentiation of sediment grain size [mainly silt， （70.72±1.94）%] and TOC [（0.20±0.06）%] and TN [（0.06±0.01）%] showed that coarse-grained substrate drove community homogenisation by optimising crab habitat conditions， whereas C/N ratios （3.12±0.83） indicated the dominance of sea-sourced organic matter， and areas of high values of TOC and TN coincided with algal and protozoan dominance coincided.The analysis of contaminants showed that the contaminants in Hangzhou Bay sediments generally showed a decreasing offshore diffusion gradient， of which DDTs [（9.45±1.68） ng/g]， brominated flame retardants were dominated by NBFRs （76.7%）， BDE209 accounted for more than 71% of the PBDEs， and the PFCs and polyfluoroalkyl substances （PFCAs accounted for 87.9% of the PFCAs） were relatively homogeneously distributed in the sediment due to their high water solubility. The distribution of perfluorinated and polyfluorinated alkyl substances （including 87.9% of PFCAs） is relatively uniform in sediments due to high water solubility. The spatial heterogeneity of habitat elements and pollutants was shaped by tidal dynamics and land-based emissions. By integrating macro-scale redundancy analysis （RDA） and micro-ecological mechanism analysis， a synergistic pattern-mechanism verification system was constructed in Hangzhou Bay. The macro-scale RDA reveals the response of biological community diversity to multi-dimensional environmental gradients， while the micro-scale RDA illustrates the differential driving effects of pollutants and environmental factors on functional communities. The mutual validation of the two systems shows that the cross-scale mutual feedback mechanism is the core pathway to analyse the emergent characteristics of ecosystems， and provides a scientific basis for the multi-stress synergistic management of large-scale strong tidal estuarine ecosystems.

Abstract:

Cyrtophorian ciliates usually dominate the microbial community in aquatic biofilms and benthic habitats， and also are the common parasites of fish. However， recent studies indicate that their diversity is underestimated. The present study investigated the morphology and ciliature of Odontochlamys shenae sp. nov. collected from freshwater in Shanghai， China， using live observation and protargol staining. The new species was characterized by a combination of morphological features: cell size about 60-80 μm × 30-33 μm in vivo， 12-15 nematodesmal rods， 6 or 7 right and 6-8 left kineties， terminal fragment consisting of 8-20 basal bodies， three contractile vacuoles and freshwater habitat. Furthermore， we reviewed the genus Odontochlamys and its biogeography shows a moderate endemicity model. In addition， a key for identifying Odontochlamys species were provided.