Table of Content

26 October 2020, Volume 42 Issue 5

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Simulated study on the effect of ecological floating bed of Sesuvium portulacastrum L. on the growth and aquaculture benefit of grouper

2020, 42(5):  411-421. 

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The intensive aquaculture relying on exogenous feed intensifies the eutrophication of seawater and leads to the increase of aquaculture diseases, which is the main factor restricting the sustainable development of mariculture. In this study, by constructing an integrated closed mariculture system combined Sesuvium portulacastrum L. with Yunlong grouper, a hybrid of E. lanceolatus (♂) and E. moara (♀), the effect of S. portulacastrum L. ecological floating bed (EFB) on grouper culture was investigated under simulated conditions, and the optimal coverage rate of EFB in culture water was explored. The results showed that after 22 days of culture, there was no significant difference in the survival rate of S. portulacastrum L. among groups (P>0.05), and a positive linear correlation between the plant weight gain rate and the EFB coverage rate was revealed (R2=0.994, P = 0.048 5), implied that the intensive fish activity could decrease the growth of S. portulacastrum L. by root damage. The survival rate, specific growth rate (SGR), feed conversion rate and output-input ratio of fish in the EFB treatment group were significantly higher than those in the control group (P<0.05), and there was no significant difference among the EFB treatment groups (P>0.05), which indicated that 15% coverage of S. portulacastrum L. EFB could improve the economic benefits of E. grouper culture tremendously. Except for T1, the weight gain rate (WGR), residual feed and fecal yield of fish in EFB treatment groups were higher than those in the control group (P<0.05), and there was no significant difference among EFB treatment groups (P>0.05), that’s to say, the fish WGR would be improved obviously as long as 30% of the water was covered with S. portulacastrum L. EFB. Similarly, the total feed quantity varied among groups, and the trend was expressed as T3> (T2, T1)>CK; in other words, S. portulacastrum L. EFB could increase the amount of feed intake and T3 (45% coverage) worked the best. What’s more, the nitrogen content of residual feed and feaces in T3 was lower than that in other groups (P<0.05), while phosphorus content stayed at the same level between groups (P>0.05), showed that feed protein utilization of fish increased in S. portulacastrum L. EFB treatment groups. Taken together, the S. portulacastrum L. EFB has obvious promoting effect upon the survival, growth and aquaculture benefit of Yunlong grouper, of which 30% coverage is the priority.

Application of high performance liquid chromatography in determination of the preponderant harmful algae species

2020, 42(5):  422-428. 

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Algae blooms is one of the great ecological disasters in China, which greatly damages to human health and sustainable development of economy. In this study, we isolated and identified 10 species of the preponderant harmful algae and 2 species green algae in the coastal area of Fujian Province. Then detected the absorption spectrum of photosynthetic pigments (ASP) in the pure cultures by high-performance liquid chromatography (HPLC) technology and conducted cluster analysis. Subsequently, we compared the ASP results of pure cultures with traditional classification. The study indicated that the further identification based on ASP could achieve more accurate classification of different algae, which could be make up the shortcomings of the traditional classification for confronting with the subtle differences of morphology. And it could be an effective supplement to algae morphology classification and molecular-biology taxonomic.

Emergency and long-term control effect of cyanobacteria bloom in Dongyaxi Reservoir

2020, 42(5):  429-444. 

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The drinking water safety of local residents is often seriously threatened by cyanobacteria bloom in the reservoir water source. Since 2010, Dongyaxi Reservoir of Sanming City has shown a trend of eutrophication, and there are always signs of algae bloom in summer. In 2014, a small-scale bloom occurred in the reservoir area. From April to July in 2015, a severe cyanobacterial bloom occurred in the Dongyaxi Reservoir. This study analyzed the emergency and long-term algae control measures adopted by Dongyaxi reservoir since July 2015. The results showed that the emergency and long-term algae control project could control algae well in summer: 1) After 23 days of emergency algal control treatment, the water body tended to be stable. As shown in detail: the algae density was reduced from 8.4×107 cells/L to 5.0×106 cells/L; Chl-a decreased from (22.73±0.22) μg/L to (9.80±0.19) μg/L; TP decreased from (0.040±0.003) mg/L to (0.018±0.003) mg/L; TN decreased from (1.21±0.04) mg/L to (0.74±0.03) mg; pH decreased from (9.28±0.13) to (8.07±0.12); CODMn decreased from (10.37 ±0.22) mg/L to (8.04±0.20) mg/L; water turbidity decreased from 22.14 mg/L to 3.27 mg/L, and the water quality recovered well. 2) After the long-term algae control technology, there was no significant change in the blank control area of the upper reaches of the reservoir, but the physical and chemical indexes and algae indexes of the water body in the upstream reservoir entry section, Huiyao Bay restoration area and the dam front restoration area were well controlled. The content of TP in the water had a very significant reduction effect, but the reduction of TN was not significant, it might be related to the removal mechanism of TN: In the process of TN removal, it was necessary to convert different forms of nitrogen in the water into nitrate nitrogen, and then used denitrification to convert it into nitrogen removal, but the denitrification process required an anaerobic environment, which contradicted the natural conditions and water oxygen, so the denitrification transformation efficiency was low, coupled with the cyanobacteria in the reservoir had a strong nitrogen fixation, so the control rate of TN was low. In summer, the content of Chl-a algae decreased obviously. In autumn and winter, algae settled into the sediment of water body in the form of dormant body to help themselves through the adverse environmental conditions. When the environmental conditions were suitable, these cysts could regerminate to form planktonic cells. Micro-nano bubble technology could destroy the resting body of algae cysts by aeration, thus destroying the secondary recovery of algae. The comprehensive nutrition index of water body showed a downward trend year by year from 2015 to 2018. The effect of the project on water purification was fine.

Research on bionic kelp harvesting device

2020, 42(5):  445-452. 

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At present, during the mechanized harvesting of kelp, kelp is retrieved by means of conveyor belt or crane. These two methods are suitable for wild kelp and kelp cultured by single rope suspension method. It is not suitable for the harvesting of kelp cultured with raft made with parallel ropes crossed on two main parallel ropes. In order to solve the problem, based on the principle of bionics, a limiter was used to simulate the artificial clenching to limit and block the movement of the pipe rope, while an electro-hydraulic push rod and a clamp were used to simulate the extension and bending of the arm. With the rope connectors, the harvesting device could complete the harvesting of kelp without untying the crossed rope or floating ball before all kelp on one raft harvested completely. At the same time, it could remove the tips and roots of kelp in the process of harvesting with two sets of cutter, and transport the main body and the tip of kelp respectively to other boats with two conveyor belts. The device could improve the labor efficiency and reduce the labor intensity.

Analysis of nutrient composition and heavy metal content of Porphyra haitanensis in different sea areas of Fujian Province

2020, 42(5):  453-462. 

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In order to explore the nutritional value and main pollutants of Porphyra haitanensis in different sea areas of Fujian Province, the contents of basic nutrients, amino acids and heavy metals of P. haitanensis in Xiapu, Zhangpu and Quanzhou were determined, and their nutritional values were compared, analyzed and evaluated. The nutritional components and quality were also analyzed and evaluated. The results showed that the protein and ash content of Quanzhou P. haitanensis was higher, the polysaccharide content of Xiapu P. haitanensis was higher, and the fat content of Zhangpu P. haitanensis was higher. The content of EAA in Xiapu P. haitanensis was higher than that in Quanzhou. Glu and Ala were the main free amino acids in P. haitanensis. The TAV values of Glu and Ala were higher than 1, which gave the P. haitanensis unique fresh and sweet flavor. Among them, the TAV values of Glu and Ala of Quanzhou and Zhangpu P. haitanensis were higher. The Pb content of P. haitanensis was in line with the national limit. The purpose of this study was to provide a reference for the development and utilization and food safety of P. haitanensis in Fujian Province.

Analysis and evaluation of nutritional components in the muscle of four grouper species

2020, 42(5):  463-472. 

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By detecting nutritional components of E. fuscoguttatus ♀×E. lanceolatus ♂, E. lanceolatus, E. fuscoguttatus and E. awoara, the nutritional value of grouper was evaluated comprehensively. The protein, water, amino acids, minerals and fatty acids of four grouper species were detected by national standard biochemical assay. The protein content and crude fat content of four grouper species were 15.18%~17.33% and 0.81%~7.04%, respectively. 18 kinds of amino acids were detected, while the essential amino acid was 41.43%~42.47% of total amino acids, which was higher than the FAO/WHO 40% scoring standard. The flavour amino acid and EAAI value were 6.34%~7.08% and 0.93~1.13, respectively, which indicated that the protein quality of four grouper species was excellent. Among the mineral elements of the four grouper species, K content was the highest of constant element and Fe content was the highest of trace element. In terms of fatty acid composition and content, 22 amino acids were higher in E. lanceolatus than in the other three grouper species. The content of polyunsaturated fatty acid accounted for 38.14% of the total fatty acids. The four grouper species contain higher DHA+EPA content, accounting for 13.58%~27.57% of the total fatty acids. Therefore, the protein quality of the four kinds of grouper was excellent, the composition ratio of amino acid and fatty acid was appropriate, and the mineral content was rich. It was an excellent aquatic product with high nutritional value and high comprehensive utilization value.

Detection of paralytic shellfish toxins in the farming shellfish products collected from the middle of Fujian sea-area by high performance liquid chromatography-tandem mass spectrometry

2020, 42(5):  473-480. 

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The paralytic shellfish toxins was investigated in farming shellfish samples collected from the middle of Fujian sea-area from the year of 2017 to 2018 by high performance liquid chromatography-tandem mass spectrometry. The results showed that: PST was not detected in the shellfish samples collected in 2018; PST was detected in the 17 batch of shellfish samples collected in 2017, with dcSTX as the most predominant components. Besides, GTX1-5 and dcGTX2-3 could also be detected in the samples. STX was not detected in the samples. The outbreak of Gymnodinium catenatum in the middle of Fujian sea-area had a certain impact on the detection of PST in the shellfish samples from the same area, including a greater impact on the mussels than oysters; but there was no impact on Sinonovacula constricta and Ruditapes philippinarum.

Tolerance study on the water temperature, salinity and dissolved oxygen changes of pearl gentian grouper (Epinephelus fuscoguttatus♀×E. lanceolatus♂)

2020, 42(5):  481-485. 

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The study was conducted to study the tolerance ability to the temperature, salinity, dissolved oxygen and other environmental factors changes of pearl pentian grouper (Epinephelus fuscoguttatus♀× E. lanceolatus♂). Healthy pearl gentian groupers were selected to conduct the gradient experiment. The average body weight of pearl gentian grouper was 121.4~277.5 g and the average body length was 174~229 mm. The results showed that the tolerance ability of pearl gentian grouper on the temperature, salinity and dissolved oxygen was widely. The optimum temperature range was 20.0~35.0℃, the lower critical temperature was 10.0℃, and the upper critical temperature was 39.0℃; the optimum salinity was 11.0~40.0, and the lower critical salinity was 3.0; the critical suffocation point was 0.70 mg/L，the DO50 was 0.67mg/L，and DO100 was 0.60 mg/L.

Metabolism and withdrawal period of eugenol in tilapia

LIN LICONG

2020, 42(5):  486-491. 

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To study the pharmacokinetic characteristics and residue elimination of eugenol in the plasma and muscle of tilapia, at water temperature of (25±1)℃, tilapia was anesthetized with 20 mg/L eugenolsolution for 24 hours, then the plasma and muscle samples were collected respectively by time period. The eugenol residues in the plasma and muscle of tilapia were determined, to determine the pharmacokinetics parameters and metabolic processes of eugenol in tilapia. Result showed that the plasma and muscle concentration-time course of eugenol both conformed to a one-compartment open model with the first order absorption. The pharmacokinetic equations were as follows: Cplasma=4.762（e-0.062 6t-e-0.064 7t），and Cmuscle=1.089（e-0.006 9t- e-0.0021 7t）.The main pharmacokinetics parameters in plasma were: T1/2kawas 14.06 h; T1/2kewas 14.68 h; and Cmaxwas 5.18 mg?kg-1.The main pharmacokinetics parameters in muscle were: T1/2kawas 84.80 h; T1/2kewas 101.48 h; and Cmax was 3.07 mg?kg-1.The absorption and eliminate speed in plasma were faster than in muscle. According to the maximum residue limit(MRL) of 0.05 mg/L, the withdrawal period should not be less than 12 days under this experiment condition when muscle was selected as target tissue. So eugenol was not recommended as an anesthetic for transportation of tilapia.

Effect of cage culture on the changes of nitrogen and phosphorus in bottom water of Zhanghu reservoir bay

2020, 42(5):  492-499. 

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Based on the data from water environment in the cage culture area of Zhanghu reservoir bay surveyed in April, July and October 2018, the seasonal changes of nitrogen (N) and phosphorus (P) in the bottom water of cage culture area were analyzed and the state of eutrophication of water body was evaluated by using comprehensive nutrition state index. The results showed that there was no significant effect on the temperature, transparency (SD), CODMn and dissolved oxygen (DO) of the bottom water of cage culture in Zhanghu reservoir bay, while the culture area significantly increased pH in summer and chlorophyll a in spring, respectively. The concentrations of seasonal mean values of total nitrogen (TN), total phosphorus (TP) and total inorganic nitrogen (DIN) in the cage culture area of Zhanghu reservoir bay were higher than those in the control area, while there was no significant difference in the concentration of PO43--P between the cage culture area and the control area (P>0.05). The concentrations of TN, TP, ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3--N) and nitrite nitrogen (NO2--N) in the cage culture area and the control area showed a seasonal trend of decreasing from spring to autumn. The concentration of PO43--P in summer was higher than that in other seasons in the cage culture area. The results of eutrophication evaluation showed that the water quality of the cage culture area was the heavy eutrophication level in spring and summer and the moderate eutrophication level in autumn, respectively.

Structure and evaluation of phytoplankton community in Jianxi watershed, Min River

li wan bao

2020, 42(5):  500-508. 

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This study mainly investigated and analyzed the phytoplankton community structure in Jianxi River Basin in May and September 2018. According to results, a total of 58 species belonging to 43 genera and 6 phyla were identified in Jianxi River Basin, mainly diatoms and green algae. The average cell density of phytoplankton in Jianxi watershed was 2.10 × 105 ind/L. The Shannon diversity index H’ and Pielou evenness index J were 3.27 and 0.76, respectively. The water quality was light-medium pollution. The water quality of Jianxi River Basin was in good condition.

On the comprehensive effect of China's aquatic seed export trade——Based on the data from 2013—2018

2020, 42(5):  509-518. 

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Aquatic product trade has played an important role in regulating the global aquatic product supply and demand structure, and exploring its comprehensive effects has become a key content of green development of fisheries. The comprehensive effect of aquatic seed export trade was evaluated by the China aquatic seed export trade data from 2013 to 2018, and then a comprehensive effect index and a zinc-integrated comprehensive effect index were constructed. It was found that economic effects showed a slow growth trend, with an average growth rate of 3.84%. The environmental effect of seawater seed was less than the freshwater seed under the same standard in different years, the average value of the total environmental effect under the standard of the lower limit tax was 306 500 Yuan. The average annual growth rate of social effects was 4.83%, which was driven by the growth trend of fishermen's per capita net income. The comprehensive effect index of aquatic seed export trade showed an increasing trend, and the average annual growth rate was 2.16%. The production process of seawater aquatic seed has positive externalities of zinc accumulation characteristics, so it is proposed to take the overall positive and negative effects on the environment as the reform direction for accounting environmental taxes of fishery, and it can also be extended to the field of agricultural products for accounting environmental effects.

Countermeasures and reflections on promoting the quality and safety management of the large yellow croaker

2020, 42(5):  519-526. 

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The large yellow croaker (Larimichthys crocea) is a unique endemic fish species in China. With the enlargement of culture scale of the large yellow croaker and the increase of its output, the products quality and safety problems of its products occur from time to time. In order to promote the healthy and sustainable development of the large yellow croaker industries, this article analyzed the new situations and problems at present quality and safety supervision working through investigating relevant enterprises, and summarized the effectiveness and experiences of safety supervision of the large yellow croaker products in Fujian. The specific countermeasures were suggested to improve the quality and safety management of the large yellow croaker products, which was expected to promote the high-quality development of the large yellow croaker industry in Fujian Province.

Research progress in the comprehensive development of oysters meat

Yong-Chang SU

2020, 42(5):  527-532. 

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Oyster is one of the traditional cultured shellfish in China. Owing to its rich in protein, glycogen, taurine and trace elements, it is a raw material for both medicine and food with important use value and economic value. At present, from the perspective of oyster food research and active substances, the processing technology of food products were optimized and extract active substances were researched. In this study, the development of oyster food, such as dry products, can products, condiments and beverage processing, as well as the development of active substances such as anti-oxidation, anti-tumor, immune enhancement, and blood pressure reduction were reviewed, in order to provide basis for the high-quality development and utilization of oyster processing industry.