Table of Content

25 December 2023, Volume 45 Issue 6

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Research Paper

Pathological analysis of scuticociliatosis of Larimichthys crocea in indoor circulating water culture

YANG Guiqin, LI Xiaodong, LU Weijing, JIANG Fan, CHEN Ziqin, ZHANG Weini, CHEN Xinhua

2023, 45(6):  523-529.  DOI: 10.14012/j.cnki.fjsc.2023.06.001

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In order to investigate the common fish diseases in indoor culture of large yellow croaker (L.crocea), this study reports the occurrence of scuticociliatosis, a parasitic disease, on the surface of L.crocea in a laboratory circulating water recirculation system. The histopathological analysis of skin, liver and muscle of L.crocea was carried out to explore the pathogenic mechanism of scuticociliatosis. At the same time, in order to further identify the body surface parasitic Scuticociliatida ciliates of L.crocea, the pathogen was isolated, and the morphological characteristics of Scuticociliatida ciliates were analyzed by in vivo formaldehyde fixed microscopic observation and scanning electron microscope observation. The results revealed the presence of whitening symptoms on the head, skin, and fin base of L.crocea. Gill cover congestion and severe cases of white massive skin ulceration were observed, along with the infestation of a significant number of Scuticociliatida ciliates. Notably, no apparent pathological alterations were detected in the body tissue. Histopathological analysis showed that the skin and subcutaneous tissue were the main sites of infection with Scuticociliatida ciliates. Tissue necrosis, cytolysis and increase of inflammatory cells occurred in most areas of muscle tissue. Myofibril was obviously broken and muscle fiber space was enlarged, while the boundary between liver tissue cells was not obvious, the central vein was oppressed, mononuclear cells increased and parenchyma cells enlarged. It was observed that the body of the pathogen was mainly slightly pointed at the top, blunt and round at the back end of the body, and contained an obvious telescopic vesicle as well as a long flagellum. The pathogen was identified as Pseudocohnilembus persalinus by morphology. Taken together, the histopathological results showed that the Scuticociliatida ciliates could infect the body surface tissue of L.crocea, resulting in loss of protection and resistance. At the same time, this study can provide a certain reference basis for indoor healthy culture of L.crocea.

Effect of chitosan oligosaccharides on non-specific immunity of Eriocheir sinensis

GAO Yujia, XU Mei, XU Yunshu, XU Tiantian, ZHANG Minna, XU Qingsong

2023, 45(6):  530-536.  DOI: 10.14012/j.cnki.fjsc.2023.06.002

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This study aimed to investigate the effect and mechanism of immune enhancer chitosan oligosaccharides (COS) on non-specific immunity of E.sinensis. A total of 45 crabs (20±2) g with intact appendages and uniform individuals were selected for the experiments, and they were randomly divided into three groups, with fifteen crabs in each group. Each crab was injected with 0.1 mL of COS at concentrations of 0 (control group), 50 and 200 μg·mL^-1, respectively. Serum and blood lymphocytes were collected 24 hours later to analyze the changes in immune enzyme activity and immune genes, etc. The results showed that compared with the control group, COS treatment significantly increased the activities of superoxide dismutase, catalase, glutathione peroxidase and lysozyme in the serum of crab, significantly increased the content of nitric oxide, and decreased the content of malondialdehyde in serum. Quantitative real-time PCR results showed that compared with the control group, COS significantly increased the expression of EsToll1, EsToll2, EsMyD88, EsTube, EsPelle and EsDorsal in the Toll signaling pathway, and up-regulated the expression of anti-lipopolysaccharide factors EsALF and EsALF3. These results suggested that COS could improve the non-specific immunity and antioxidant capacity of E.sinensis, activate the Toll signaling pathway, and promote the expression of anti-lipopolysaccharide factors. This study provided theoretical support for the application of COS in E.sinensis.

Development of microsatellite markers in Macrobrachium nipponense based on sequencing genotyping

LIU Kai, XIE Nan, WANG Yuxi, LIU Xinyi

2023, 45(6):  537-543.  DOI: 10.14012/j.cnki.fjsc.2023.06.003

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The microsatellite sequences were obtained using a simple sequence repeats (SSR) development method without needing a reference genome and were genotyped through sequencing. The ebwt2InDel software was utilized to identify Insertion/Deletion (InDel)-containing sequences from the whole genome sequencing data of two samples. Using MISA software, 111 perfect SSR-containing sequences were obtained from the InDel-containing sequences by eliminating non-SSR-containing sequences. The SSRgenotyper software was then used to analyze the polymorphism of 30 M.nipponrnse samples, successfully genotyping 19 out of the 111 SSR-containing sequences with a genotyping success rate of 17.12%. Successful genotyping was achieved at 19 SSR loci, all exhibiting 3-base repeats ranging from 4 to 6. Among them, the highest proportion of repetitive sequences was observed with the ATC/ATG unit, accounting for six loci (31.58%). Two of the 19 SSR markers had low polymorphism information content, and 17 had moderate polymorphism information content. These 19 microsatellite markers helped to evaluate the genetic parameters of freshwater shrimp populations and develop freshwater shrimp germplasm resources.

Preliminary study on resource distribution and resource density of sea cucumbers in Pingtan sea area of Fujian Province

CAI Jiandi, WU Jianshao, MA Chao, FAN Yilong, LIU Yong, XU Chunyan, LIN Qi, YANG Qiuhua

2023, 45(6):  544-550.  DOI: 10.14012/j.cnki.fjsc.2023.06.004

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This study was performed to explore the distribution and resources of natural sea cucumbers in the inshore aquaculture area in Pingtan District (Fujian Province, China). The study conducted surveys to collect information on species, biology, resource amount, fishing amount, and fishing output value of sea cucumbers in the coastal aquaculture area of Pingtan in April, May, and June 2023. Moreover, the samples of sea cucumbers (n=242) were sampled and used for classification. The results showed that all samples were identified as Apostichopus japonicus. Biological measurement results showed that sea cucumbers collected in April, May, and June reveal average body lengths of (131.7±44.3), (150.1±40.6) and (114.9±28.3) mm, average body weights of (52.2±41.6), (108.3±55.9), (56.1±32.2) g, feeding levels of 3~4, 1~4, and 0~3, respectively. Furthermore, the questionnaire survey results of six fishing boats showed that the average sea cucumber catch per boat in April, May, and June was 1 050.0, 683.3, and 233.3 kg, respectively.This is the first report on the possible existence of a self-propagating population of sea cucumber in Pingtan sea area,which provides information on the resources of sea cucumber in Fujian Province.

Effects of Gymnodinium catenatum on the clearance rate of Perna viridis

XU Cuiya, YANG Fang, CHEN Xiaohong, CHEN Caizhen

2023, 45(6):  551-558.  DOI: 10.14012/j.cnki.fjsc.2023.06.005

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The present study was conducted to investigate the impact of G.catenatum on the feeding behavior of P.viridis. An experimental group fed with G.catenatum and a control group fed with Skeletonema costatum were established. Short-term (1 hour) and long-term (38 days) clearance rate experiments were carried out. The results showed that the clearance rate of P.viridis, whether feeding on toxic or non-toxic algae, as the densty of algae cells increased, initially increased and then decreased, reaching the peak when the algal cell density approached the threshold density for red tide. The highest clearance rates observed in the experimental and control groups were (3.04±0.02) and (3.70±0.03) L/(g·h), respectively. Compared to the control group, the clearance rate of P.viridis in the experimental group exhibited a significant decrease (P<0.05), indicating that G.catenatum had an influence on the feeding behavior of P.viridis. Furthermore, the long-term filtration did not cause significant changes in the clearance rate, which remained relatively stable at the initial level.

Study of AVS-SEM in surface sediments in cage farming of Zhanghu reservoir bay, Fujian Province

JIANG Yixiong, JIANG Dongsheng, CHEN Zhi, ZOU Lizhen, CUI Lifeng, LIAN Chenyang

2023, 45(6):  559-568.  DOI: 10.14012/j.cnki.fjsc.2023.06.006

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In order to investigate the potential ecological risks of heavy metals at cage farming in surface sediments, 5 samples were collected from Zhanghu reservoir bay in Shuikou reservoir and the acid volatile sulfide (AVS) and simultaneously extracted metals (SEM) were studied. The results indicated that the AVS concentrations ranged from 0.57-2.13 μmol·g^-1, and the SEM concentrations ranged from 1.66-6.35 μmol·g^-1. Among heavy metals, Zn, Cr and Cu were the dominating metals, accounting for over 80% of SEM. By comparing the ratio of SEM to AVS, the values of annual average were ranged from 1.65-9.11. If Cr was not included in the calculation, the values were ranged from 1.42-7.75, and the value of (SEM-AVS) were mainly smaller than 5. These indicated that heavy metals were associated with the AVS phase in the sediments, while metals in surface sediments could not cause toxicity to benthic organism. Compared with the threshold of toxic effects, the most toxic metal was Pb in terms of individual heavy metals. According to the present study, the potential toxic effects of heavy metal release and hydrogen sulfide (H₂S) production from sulfides on cage aquaculture should be on the alert.

A comparative study on the nutrient and fatty acid composition in muscle of Siniperca scherzeri in upstream and downstream area of Yalu River

JIANG Xianghui, WANG Xingbing, KOU Lingxiao, WEI Hongxiang, LIU Yong, ZHANG Tao

2023, 45(6):  569-576.  DOI: 10.14012/j.cnki.fjsc.2023.06.007

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To figure out the different nutritional quality of S.scherzeri muscle from different habitats, this study determined and compared the nutritional compositions, as well as fatty acids composition and content of S.scherzeri. The results showed that there was significantly higher crude fat content in the muscle of S.scherzeri in upstream area than that in the muscle of S.scherzeri in downstream area (P<0.05), without significance in content of moisture, crude protein and ash between these two groups (P>0.05). There are 16 kinds of fatty acids in the muscle of S.scherzeri in upstream area and 17 in downstream area. The saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids occupied 35.886%, 34.184% and 29.922% in the muscle of S.scherzeri in upstream area, occupied 34.913%, 34.895% and 30.181% in the muscle of S.scherzeri in downstream area, respectively. And for the composition of fatty acid, the essential fatty acid occupied 11.735%, the ratio of ω-6/ω-3 was 0.919,EPA and DHA was 11.672% in the muscle of S.scherzeri in upstream area. The essential fatty acid occupied 9.571%, the ratio of ω-6/ω-3 was 0.781,EPA and DHA was 12.939% in the muscle of S.scherzeri in downstream area. In conclusion,the nutritive value of fatty acid in the muscle of S.scherzeri in upstream area was better than that of S.scherzeri in downstream area.

Nutritional analysis and comprehensive evaluation of by-products of sea cucumber(Apostichopus japonicus)

WANG Yangduo, SU Yongchang, WANG Xiaoyan, SHI Wenzheng, LIU Zhiyu

2023, 45(6):  577-584.  DOI: 10.14012/j.cnki.fjsc.2023.06.008

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This article focused on the typical processing by-products of sea cucumber (A.japonicus), including intestines and ovum, to explore their nutritional composition and conduct a comprehensive evaluation by comparing them with body walls. The results showed that the crude protein, crude fat, ash, and total sugar contents in sea cucumber intestines and ovum were 68.85%, 13.53%, 9.96%, 0%,and 58.18%, 12.24%, 19.01%, 2.36%, respectively. In comparison to the body walls, the by-products exhibited higher crude protein and fat contents, but lower ash and total sugar contents. The intestines and ovum were found to contain 18 different amino acids, constituting 68.15% and 51.38% of the total amount, respectively. The ratio of essential to non-essential amino acids was 65.17% and 61.37%, respectively, with essential amino acids accounting for 39.46% and 38.03% of the total amino acids. The essential amino acid index was 94.85 and 67.73, respectively, suggesting that both the intestines and ovum possessed high nutritional value as they exhibited a good balance effect of amino acid components, identifying them as ideal protein sources. The unsaturated fatty acids constituted a similar proportion of total fatty acids, with 80.82% and 80.74%, respectively. Notably, EPA and DHA were the major components of these fatty acids. Additionally, five macro elements and five trace elements were detected, with sodium and iron being the primary elements. This study serves as a foundation for the high-value utilization of sea cucumber by-products and the development of active substances.

Design of actuator and control system for kelp automatic knotting machine

HUANG Guifang, LIN Jianwei, WEI Guanyuan, DING Lan, CAI Wenhong, WEI Shengjun

2023, 45(6):  585-592.  DOI: 10.14012/j.cnki.fjsc.2023.06.009

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The kelp knots are the main product for exporting and earning foreign exchange in Chinese kelp culture provinces, but there are no mechanical processing devices. Therefore, the kelp knots are usually tied manually. Based on the principle of bionics, this paper offered an automatic knotting machine which could make the kelp forming a circle and passing through it to form a knot with the logic circuit. The test verified that this knotting machine was able to complete the operational requirements for kelp knotting accurately, which showed that this design was reasonable and feasible, and had the value of promotion and application after further optimization. It could also provide certain reference for the design and application of relevant knotting equipment.

Review

Advances of genetic engineering modification in Chlorella

ZHANG Tiantian, CHEN Bilian, ZHENG Mingmin

2023, 45(6):  593-602.  DOI: 10.14012/j.cnki.fjsc.2023.06.010

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Chlorella is a unicellular microalga that could grow and accumulate biomass through photosynthesis using sunlight and carbon dioxide. It is widely used to produce biofuels and other high-value products in fields like aquaculture, food, energy, and the environment. With the development of genetic engineering technology, research and applications of Chlorella at the molecular level have received increasing attention, making specific genetic modification possible. In this paper, we summarized and discussed the application of Chlorella in genetic engineering and protein production from four perspectives: transformation system, transformation methods, factors affecting transformation and expression of exogenous proteins. The aim of this review was to provide theoretical support and references for high-value products production of Chlorella.

Development status and countermeasure analysis of mainstream low carbon aquaculture technology at home and abroad under the double carbon background

FENG Ying, ZENG Ya, REN Tongjun

2023, 45(6):  603-613.  DOI: 10.14012/j.cnki.fjsc.2023.06.011

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Carbon peaking and carbon neutrality are important measures to address climate change in China. Carbon emission reduction in aquaculture is crucial to achieving the dual carbon target. Therefore, studying and exploring low-carbon aquaculture technology has important practical significance. Based on the concept of low carbon development and the background of dual carbon goals, the present study analyzed the current situation and trends of low carbon aquaculture technology development at home and abroad, discussed the urgent issues to be solved in the development of low carbon aquaculture technology in China, and proposed relevant countermeasures in terms of innovation of low carbon technology, improvement of policies and regulations, and construction of professional personnel in combination with China’s national conditions, aiming at effectively reducing greenhouse gas emissions from China’s aquaculture industry,promoting high-quality green transformation of aquaculture industry to provide scientific reference and contribute to the realization of China’s dual carbon vision.

Discussion on establishing a service system for Fujian deeper offshore aquaculture industry

WANG Xiaowei, CHEN Xifei, LI Miaomiao, KANG Jianping

2023, 45(6):  614-620.  DOI: 10.14012/j.cnki.fjsc.2023.06.012

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Deeper offshore aquaculture plays a crucial role in mitigating the ecological pressures in nearshore waters, expanding the aquaculture industry’s development space, and offering high-quality green aquatic products. In Fujian Province, the deeper offshore aquaculture is still in its early stages, and it has introduced the “Fujian Province Pilot Work Plan (2021—2023) For Deepsea Equipment Breeding Project” to research and tackle the technological challenges related to this industry. The plan aims to establish a complete industry chain, enhance the industrial service system, and explore novel fields, mechanisms, and models for deeper offshore aquaculture. This paper is centered around the developmental requirements of the deep-sea aquaculture industry and follows a problem-oriented approach. It presents an industry development service system for deeper offshore aquaculture that consists of three main links and six systems,including infrastructure construction services and financial support services during the pre-production stage, production technology services and industrial supply chain services during the mid-production stage, and brand building services and processing and circulation services during the post-production stage. Moreover, it provides strategies and suggestions for constructing a service system, aiming to establish a comprehensive support system that enables the sustainable development of the deep-sea aquaculture industry.