Current status and prospect of fisheries resource enhancement in Tianjin

Based on the data of releasing and enhancement of Tianjin Bohai Sea Fisheries Research Institute,this study has entirely summarized the experiences and achievements on releasing and enhancement works in Tianjin since 2006.Since 2006,Tianjin has launched the first multi-proliferation and release activity with"Fenneropenaeus chinensis"as the leader.So far,more than 22 varieties have been proliferated,among which crustaceans are dominant.There are significant ecological,economic and social benefits.Both national and international development trends of releasing and enhancement are summarized,and demands and objective of industrial development are proposed.

The characteristic of phytoplankton community and its variation at artificial reef area of the coastal sea of Tianjin

Three cruises were investigated respectively in May,July and November 2016 in the artificial reef area of 2010,2012,and 2014 and the non-artificial reef area(control area)in the coastal area of Tianjin.Each area had 3 sampling stations,a total of 12 sites.The result showed that 58 taxa of phytoplankton were identified which belongs to 2 phyla 28 genera,Among these species,bacillariophyta including 19 genera 44 species,pyrrhophyta including 9 genera and 14 species.Give priority to with diatom species,accounting for 75.9%of the total species,followed by dinoflagellates,accounting for 24.1%.Dominant phytoplankton species give priority to with coscinodiscus and Chaetoceros of bacillariophyta,mainly including Coscinodiscus wailesii,C.asteromphalus,C.granii,C.oculus-iridis,C.spp.,Chaetoceros castracanei,C.lorenzianus,C.curvisetus,Pseudo-nitzschiapungens,Guianardia delicatula,Rhizosolenia setigera,Proboscia alata f.indica and Noctilluca scintillans.Phytoplankton cell abundance revealed obviously seasonal changes,the average cell abundance respectively was 94.79×10^4 cells/m^4、39.53×10^4 cells/m^4 and 21.5×10^4 cells/m^3.Phytoplankton diversity index has obviously seasonal variation,and in November,shannon-wiener diversity index,Margalef index and Pielou index are higher than in May and July.Comparing the artificial reef areas with the control area,the phytoplankton cells abundance of the control area in May was significantly higher than the artificial reef areas.In July and November,the artificial reef area of 2014 phytoplankton cell abundance was significantly higher than other artificial reef area and the control area.Diversity index of phytoplankton in the control area and the artificial reef of 2012 was lower than the artificial reef area of 2010 and 2014,and lowest in non-artificial reef areas.Obviously,the construction of artificial reef had significant effect for the improvement of the phytoplankton community diversity,but the phytoplankton community diversity is not always increasing and fluctuating to a certain extent as time goes by.

A preliminary discussion on the construction of marine ranching in Tianjin

Introduces the development connotation,development ideas,practice history and future prospects of Tianjin Ocean Ranch under the background of the development of national marine pastures.Combine the development process of China's marine pastures with the practice of Tianjin Ocean Ranch,the development characteristics of Tianjin marine pastures are analyzed.It is concluded that,for the future construction of Tianjin Ocean Ranch,we can focus on promoting the transformation of marine development mode to recycling,and construct a marine space development pattern of land-sea coordination and human-sea harmony,in order to accelerate the realization of Tianjin's"One Base and Three Districts"objective.We will make greater contributions to the quality of a well-off society and the creation of a beautiful new environment in Tianjin.Modern marine pastures are a long-term,complex and scientific systematic project that requires great attention and attention from all walks of life.

Numerical research on water exchange of artificial reef in Yangmeikeng

Computational Fluid Dynamics(CFD)simulation is used in the study of water exchange capability,water residence time and conservative substance distribution in Yangmeikeng artificial reef area,which were helpful to marine environmental quality assessment and marine ecological changing mechanism research of artificial reef area.Furthermore the distance of reef clusters is changed to investigate the hydrodynamic characters and water exchange capability of the whole reef area in order to analyze the reasonable layout of artificial reef area.

Influence of the northern Yellow Sea Cold Water Mass on picoplankton distribution around the Zhangzi Island,northern Yellow Sea

Picoplankton distribution around the Zhangzi Island（northern Yellow Sea）was investigated by monthly observation from July 2009 to June 2010.Three picoplankton populations were discriminated by flow cytometry,namely Synechococcus,picoeukaryotes and heterotrophic prokaryotes.In summer（from July to September）,the edge of the northern Yellow Sea Cold Water Mass（NYSCWM）resulting from water column stratification was observed.In the NYSCWM,picoplankton（including Synechococcus,picoeukaryotes and heterotrophic prokaryotes）distributed synchronically with extremely high abundance in the thermocline（20 m）in July and August（especially in August）,whereas in the bottom zone of the NYSCWM（below 30 m）,picoplankton abundance was quite low.Synechococcus,picoeukaryotes and heterotrophic prokaryotes showed similar response to the NYSCWM,indicating they had similar regulating mechanism under the influence of NYSCWM.Whereas in the non-NYSCWM,Synechococcus,picoeukaryotes and heterotrophic prokaryotes exhibited different distribution patterns,suggesting they had different controlling mechanisms.Statistical analysis indicated that temperature,nutrients（NO3^and PO4^3-）and ciliate were important factors in regulating picoplankton distribution.The results in this study suggested that the physical event NYSCWM,had strong influence on picoplankton distribution around the Zhangzi Island in the northern Yellow Sea.

Linking Structural Equation Modeling with Bayesian Network and Its Application to Coastal Phytoplankton Dynamics in the Bohai Bay

Bayesian networks （BN） have many advantages over other methods in ecological modeling, and have become an increasingly popular modeling tool. However, BN are flawed in regard to building models based on inadequate existing knowledge. To overcome this limitation, we propose a new method that links BN with structural equation modeling （SEM）. In this method, SEM is used to improve the model structure for BN. This method was used to simulate coastal phytoplankton dynamics in the Bohai Bay. We demonstrate that this hybrid approach minimizes the need for expert elicitation, generates more reasonable structures for BN models, and increases the BN model＇s accuracy and reliability. These results suggest that the inclusion of SEM for testing and verifying the theoretical structure during the initial construction stage improves the effectiveness of BN models, especially for complex eco-environment systems. The results also demonstrate that in the Bohai Bay, while phytoplankton biomass has the greatest influence on phytoplankton dynamics, the impact of nutrients on phytoplankton dynamics is larger than the influence of the physical environment in summer. Furthermore, although the Redfield ratio indicates that phosphorus should be the primary nutrient limiting factor, our results show that silicate plays the most important role in regulating phytoplankton dynamics in the Bohai Bay.

Preliminary study on the cultivation of Porphyra yezoensis in Bohai bay

Sampling survey was carried out on the whole growth cycle(except the ice period from mid-January to mid-march next year)of Porphyra yezoensis breeding in Bohai Bay from late November 2017 to early May 2018,and the marine environment factor were monitored at the same time.According to the the analysis of the growth condition of P.yezoensis and the environmental factors,the preliminary results confirmed that P.yezoensis could grow well in the Bohai Bay,the water temperature,salinity,pH and Nitrite are important environmental factors to limit its growth,if hanging net curtain in time when environmental conditions in the area is suitable for the growth of P.yezoensis that its growth period will be extended to five months.Survey also found that how to streak through the winter ice period is the key problems to be solved for P.yezoensis cultivation in the area,this study also puts forward two kinds of schemes,which is the effective method remains to be further tested.

Corrosion life of artificial reef under natural seawater conditions

Corrosion of steel bars with chloride salt erosion is one of the main reasons for the deterioration of the performance of reinforced concrete structures.The key to the service life of concrete members is the transport rate of chloride ions and the time for rusting of steel bars.In this paper,the artificial reef concrete member is taken as the research object,and the diffusion coefficient of seawater chloride ion in C30,C35 and steel slag composite artificial reef concrete is analyzed.The critical chloride ion concentration of steel corrosion in concrete is used as the boundary condition for life prediction.The chloride ion diffusion model predicts the corrosion life of C30,C35 and steel slag composite artificial reefs in seawater.The results show that the diffusion law of chloride ions in concrete artificial reefs basically meets Fick's second law.The corrosion life of C30,C35 and steel slag composite concrete reefs was calculated by the model to be 51.6,54.8 and 56.8 years,respectively.

Plankton respiration in the northern South China Sea during summer and winter

Plankton respiration is an important part of the carbon cycle and significantly affects the balance of autotrophic assimilation and heterotrophic production in oceanic ecosystems. In the present study, respiration rates of the euphotic zone plankton community（CR_（eu））, size fractionated chlorophyll a concentration（Chl a）, bacterial abundance（BAC）, and dissolved oxygen concentration（DO） were investigated during winter and summer in the northern South China Sea（n SCS）. The results show that there were obvious spatial and temporal variations in CR_（eu） in the n SCS（ranging from 0.03 to 1.10 μmol/（L·h））, CR_（eu） in winter（（0.53±0.27） μmol/（L·h）） was two times higher than that in summer（（0.26±0.20） μmol/（L·h））, and decreased gradually from the coastal zone to the open sea. The distribution of CR_（eu） was affected by coupled physical-chemical-biological processes, driven by monsoon events. The results also show that CR_（eu） was positively correlated with Chl a, BAC, and DO, and that BAC contributed the highest CR_（eu） variability. Furthermore, the results of the stepwise multiple linear regression suggest that bacteria and phytoplankton were the dominant factors in determining CR_（eu）（R^2 = 0.82, p〈0.05） in the n SCS. Based on this relationship, we estimated the integrated water column respiration rate（CRint） within 100 m of the investigated area, and found that the relationship between the biomass of the plankton community and respiration may be nonlinear in the water column.

Community structure of zooplankton in reef area and its relationship with environmental factors

To better understand the community structure characteristics of zooplankton in the artificial reef area of Tianjin in the Bohai Bay and its relationship with major environmental factors,the project conducted three cruise surveys in the spring(May),summer(July)and autumn(October)of 2016 and monitored conventional environmental factors.The results showed that there were 36 species of zooplankton,including 14 species of copepods,phytoplankton larvae 12 species;6 kinds of coelenterates;3 species of shrimp and 1 species of hairy shrimp in the artificial reef area of Tianjin in the three cruise surveys.The dominant species in spring,summer,and autumn have obvious changes,among which the dominant species in spring are Eurytemora pacifica,Clytia hemisphoerica,Clalnus sinicus,and Macruran larva;in summer are Oithona similis and Brachyura zoea larva;and autumn only the Clalnus sinicus.Correlation analysis shows that the diversity and uniformity of zooplankton in the artificial reef area have increased to varying degrees,indicating that the overall construction of artificial reefs in the Tianjin sea area has improved the marine ecological protection to some extent.The results of CCA showed that salinity and water temperature were the main environmental factors affecting the distribution of zooplankton communities in artificial reefs in Tianjin.

Potential ecological risks of Cd for different benthos in artificial reefs

Inductively coupled plasma mass spectrometry is used to detect Cdforbenthos in the artificial reef .The results show that： Cd of benthos is varied from0.011μg/L to 0.541 μg/L, and averages 0.188 ± 0.220 μg/L. The distribution of Cddecreased in the order： gonads〉 gills〉 muscle in different tissues. The enrichmentregalurity in muscle Cd of different benthos was Oratosquilla, crab, fish, shrimp,ocellatus. Its health risk factor is far less than 1, indicating that Cd hasn’t obvious healthrishks on exposure population.