Metapenaeus Ensis Research Articles

Characterization and mechanism of phthalic acid esters bioaccumulation in dominant mangrove fish at different habitats in the mangrove ecosystem of Dongzhai Harbor, China

With the wide application of phthalic acid esters (PAEs) in the manufacturing of plastic products, a large number of PAEs were discharged into marine ecosystem and accumulated in fish, which has posed a serious threat to marine ecological environment and fishery resources. However, the bioaccumulation of PAEs in fish in mangrove ecosystem, the most productive marine ecosystem, has not been well characterized. In this study, dominant fish and their potential food sources (including particulate organic matter (POM), sedimentary organic matter (SOM), Metapenaeus ensis (Shrimp) and Oreochromis (Ore) were collected from Dongzhai Harbor, a typical mangrove ecosystem. The concentrations of nine PAEs in fish and their potential food sources were determined. Then stable nitrogen and carbon isotope analysis, combined with a new Bayesian mixing model (MixSIMMR) was used to quantify the diet compositions of fish and elucidate the effect of dietary habit on PAEs bioaccumulation in fish. The results indicated that the median concentration of ∑9PAEs in fish was 1119 μg/kg ww, positioning it at a moderate to low level in comparison to other regions. di-n-butyl phthalate (DBP) and diisononyl ortho-phthalate (DINP) were the dominant PAEs in fish. The PAEs concentration in demersal fish was significantly higher than that of pelagic fish, which may be attributed to the substantial contributions of shrimp (28.5 %) and POM (25.3 %) to the diet of demersal fish. This study provided new insights on the bioaccumulation of PAEs in dominant mangrove fish and confirmed that habitat preferences and food sources could significantly influence the bioaccumulation of PAEs in fish.

Experimental assessment of ozonated ice: Preparation, stability, and preservation effects on shrimp (Metapenaeus ensis)

Ozonated ice not only retains the inherent performance and function of ozone, but also serves as a cold source for food preservation. However, its preparation is challenging due to the low solubility and instability of ozone in water. So here, the major preparation techniques and the storage stability of ozonated water and ice were studied. Besides, the impact of ozonated ice treatment on the quality of shrimp (Metapenaeus ensis) was explored. To achieve these ends, a set of ozonated ice preparation devices was established, and the optimal conditions for producing ozonated water and ice were confirmed as follows: using 0 °C deionized water as the water source, achieving an outlet flow rate of 80 L/h, cyclically mixing gas-liquid twice, adding 1.0 g/kg of polyoxypropylene oxyethylene glycol ether (POGE), and freezing at −80 °C. Regarding ozone stability, an increase in initial ozone concentration and storage temperature, along with a decrease in water purity, resulted in a shorter half-life of ozone in water. Additionally, a lower storage temperature was conducive to prolonging the half-life of ozonated ice, while the addition of POGE had little effect. In practical application, under the optimal conditions for producing ozonated water and ice without POGE, shrimp stored in ozonated ice demonstrated superior sensory scores, whiteness values, and shear force compared to those stored in normal ice. Concurrently, they displayed reduced levels of TVC, TVB-N, and pH. Furthermore, the application of ozonated ice treatment mitigated blackening and improved odor quality. Consequently, this research offers a scientific foundation for the industrial application of ozonated water and ice and serves as a reference for preventing the deterioration and quality loss of shrimp and other seafood products.

Effects of dietary lipid levels on growth, lipid metabolism, fatty acid composition and antioxidant capacity of juvenile greasyback shrimp (Metapenaeus ensis)

The optimal dietary lipid requirement and underlying lipid metabolic mechanisms remain elusive in greasyback shrimp (Metapenaeus ensis), presenting significant obstacles to the advancement of their culture development. Five isonitrogenous diets (38.39% crude protein) containing lipid levels of 2.25%, 4.72%, 7.50%, 10.18%, and 12.71% were formulated to evaluate the effects of dietary lipid levels on growth, lipid metabolism, fatty acid composition and antioxidant capacity of juvenile greasyback shrimp. The results indicated that shrimps fed a diet with 7.50% lipid exhibited significantly higher percent weight gain (161.36%) and specific growth rate (1.72%/d) than those fed other diets (P < 0.05). As the dietary fat content increased, the lipid levels of the whole shrimp, muscle, hepatopancreas, and serum exhibited similar elevations. Concurrently, H&E staining clearly revealed the occurrence of hepatocyte swelling and hepatocyte vacuolization in the 10.18% and 12.71% groups, and hepatic lipid accumulation was further observed in these groups by Oil red O staining. In addition, with the increase in dietary fat levels, saturated fatty acids (SFA) decreased and polyunsaturated fatty acids (PUFA) increased in both hepatopancreas and muscle. The expression of genes involved in lipogenesis (fas, acc and dgat) was initially up-regulated and subsequently down-regulated with increasing dietary lipid levels, whereas the expression trends of lipolysis genes (hsl, atgl) remained similar. The mRNA levels of genes associated with long-chain PUFA biosynthesis (elovl5, lxrβ, srebp1) and fatty acid oxidation (cpt1, acox1) in the hepatopancreas of shrimp fed a diet with 7.50% lipid were significantly elevated compared to those in other dietary groups (P < 0.05). With the increase in dietary fat levels, the expression of fatty acid transport genes fatp4 and fabp1 was up-regulated. Antioxidant enzyme activities in the hepatopancreas initially increased with dietary lipid levels, peaking in shrimp fed the 7.50% lipid diet, but subsequently declined. In conclusion, optimal dietary fat levels enhance growth performance, while high lipid levels impede growth, decrease antioxidant enzyme activities, and regulate lipid deposition in greasyback shrimp by modulating lipid metabolic pathways.

A First Look at Genetic Diversity of Metapenaeus ensis Populations in Tam Giang – Cau Hai Lagoon, Vietnam

This study investigates the genetic diversity and population structure of the greasyback shrimp, Metapenaeus ensis (De Haan, 1844), within the Tam Giang – Cau Hai lagoon, Vietnam, by analyzing mtCOI genes from 91 individuals collected across four populations in nine sampling locations. High genetic diversity was found, with 34 unique haplotypes and 38 genetic variations identified. Most genetic variation occurred within populations (AMOVA), suggesting high gene flow. Low and non-significant Fst values and close genetic distances confirmed minimal differentiation among populations. These findings provide the first insights into M. ensis population genetics in this lagoon, informing conservation and management efforts. Understanding genetic diversity is crucial for sustainable management and conservation of marine species. This research aids in understanding population resilience, potential impacts of overfishing, and may assist in developing sustainable harvest strategies of this economically important shrimp species.

Effects of Dietary Protein Levels on Growth, Digestive Enzyme Activity, Antioxidant Capacity, and Gene Expression Related to Muscle Growth and Protein Synthesis of Juvenile Greasyback Shrimp (Metapenaeus ensis).

An 8-week feeding trial was conducted to assess the effects on growth, antioxidant capacity, digestive enzyme activity, and gene expression related to muscle growth and protein synthesis of juvenile greasyback shrimp (Metapenaeus ensis) using five experimental diets containing 29.37%, 34.30%, 39.11%, 44.05%, and 49.32% of protein. The results demonstrated that juvenile greasyback shrimp consuming 39.11%, 44.05%, and 49.32% dietary protein had a significantly higher final body weight (FBW), weight gain (WG), feed conversion ratio (FCR), and specific growth rate (SGR) than other groups (p < 0.05). The protein efficiency ratio (PER) showed a significantly quadratic pattern with increasing dietary protein levels (p < 0.05). The highest trypsin and pepsin activities were observed in the group with a protein level of 44.05% (p < 0.05). Relatively higher superoxide dismutase (SOD) activity was found in groups with protein levels of 39.11% (p < 0.05). Alkaline phosphatase (AKP) and catalase (CAT) activity showed a significantly linear increasing pattern with increasing protein intake up to 44.05%, and then decreased gradually (p < 0.05). Compared to the dietary 29.37% protein level, the expression levels of myogenic regulatory factors (mef2α, mlc, and myf5) and mTOR pathway (mtor, s6k, akt, and pi3k)-related genes were significantly up-regulated in muscle with 39.11%, 44.05%, and 49.32% dietary protein levels (p < 0.05). The AAR pathway (gcn2, eif2α, and atf4)-related gene expression levels were significantly lower in muscles with 39.11%, 44.05%, and 49.32% protein levels than in other groups (p < 0.05). Based on the broken-line regression analysis of SGR, the estimated appropriate dietary protein requirement for juvenile greasyback shrimp is 38.59%.

Analisis Hasil Tangkapan Udang Brown (Metapenaeus ensis) di Pelabuhan Perikanan Kuala Pembuang

This study aims to determine the results of Catch Per Unit Effort (CPUE), Maximum Sustainable Yield (MSY) and the utilization rate of brown shrimp (Metapenaeus ensis) at the Kuala Pemburan Fishing Port for the last 5 years (2017-2021). The basic method used in this study is a quantitative descriptive method derived from primary and secondary data. Data collection techniques were interviews and primary data collection in the form of shrimp production data at the Kuala Pemburan Fishing Port. Data analysis methods are CPUE, MSY and utilization rate analysis. The results of the study show that the CPUE value has fluctuated from 2017-2021. The highest CPUE value was in 2020 which was 37.76 kg/trip and the lowest was in 2017 which was 8.36 kg/trip. The high and low CPUE values ​​occurred because during this period there was an increase and decrease in both the use of fishing gear and fishing trips. For the yield value (MSY) the optimum fishing effort is 2,940 trips per year and the maximum sustainable catch value is 63,954 kg per year. If viewed based on the sustainable maximum catch value, the number of catches produced in 2020 and 2021 has exceeded the maximum catch limit (Cmsy), but the fishing effort has not exceeded the optimum fishing effort (Emsy). Meanwhile, the yield value of the utilization rate of brown shrimp resources in the last five years indicates that the utilization rate has increased drastically, especially in 2020 and 2021

A novel medium for long-term primary culture of hemocytes of Metapenaeus ensis

The development of a suitable shrimp cell medium is essential for achieving a long-term cell culture and finite cell line of shrimps routinely. In this study, we have successfully developed an optimal shrimp cell medium that can be used for long-term in vitro culture and continuous subculture of the hemolymph cells (or hemocytes) of greasyback shrimp Metapenaeus ensis, designated as MeH cells, by shrimp serum-based and supplements-based optimization of the basic and growth medium. In this article, we have focused on the details for the preparation of the optimal shrimp cell medium by diluting and mixing of various stock solutions as well as the methods for isolation and primary culture of MeH cells.•A novel shrimp cell growth medium is developed for long-term shrimp hemocytes culture.•The preparation method of shrimp cell growth medium is successfully established.•Obvious cell activity and proliferation potential of isolated shrimp cells can be maintained beyond 30 days.

Sustainable preparation of hierarchical porous carbon from discarded shells of crustaceans for efficient CO2 capture

The improved CO2 adsorption capacity and selectivity is the focus of research on the carbon-based CO2 adsorbent, while nitrogen-containing groups on the surface of adsorbent have an important effect on the CO2 adsorption. In this study, nitrogen self-doped hierarchical porous carbon was prepared from three kinds of crustacean shells, namely, hairy crab shell, crayfish shell and greasyback shrimp shell. It revealed that the pore structure of porous carbon can be regulated well with the varied activation temperature and the amount of KOH. With the favorable activation temperature of 800℃ and the mass ratio of activator to carbon (A/C) of 1:1, the obtained porous carbon with different carbon precursors exhibited relatively high specific surface area (1430.63–1734.64 m2/g), large pore volume (0.70–1.48 cm3/g) and developed pore-size distribution. Consequently, among the three kinds of hierarchical porous carbon tested, that prepared form greasyback shrimp displayed the excellent CO2 adsorption of 5.144 and 4.325 mmol/g at 1 bar, 273 K and 298 K and the highest CO2/N2 selectivity was observed of 32.32, attributed to the volume of mesopore and micropore and the type of nitrogen-containing groups. The effects of nitrogen-containing groups in porous carbon on the CO2 adsorption and CO2/N2 selectivity were analyzed, and it revealed that the CO2/N2 selectivity of porous carbon was positively correlated with pyrrolic N. In conclusion, the porous structures and nitrogen-containing groups of porous carbons both contribute to the CO2 adsorption and selectivity. The porous carbon with well recycling performance in this study presented a practical application prospect.

First transcriptome profiling in gill and hepatopancrease tissues of Metapenaeus ensis in response to acute ammonia-N stress.

The greasyback shrimp, Metapenaeus ensis, suffers from ammonia-N stress during intensive factory aquaculture. Optimizing ammonia-N stress tolerance has become an important issue in M. ensis breeding. The metabolic and adaptive mechanisms of ammonia-N toxicity in M. ensis have not been comprehensively understood yet. In this study, a large number of potential simple sequence repeats (SSRs) in the transcriptome of M. ensis were identified. Differentially expressed genes (DEGs) in the gill and hepatopancreas at 24h post-challenges under high concentrations of ammonia-N treatment were detected. We obtained 20,108,851-27,681,918 clean reads from the control and high groups, assembled and clustered a total of 103,174 unigenes with an average of 876 bp and an N50 of 1189 bp. Comparative transcriptome analyses identified 2000 different expressed genes in the gill and 2010 different expressed genes in the hepatopancreas, a large number of which were related to immune function, oxidative stress, metabolic regulation, and apoptosis. The results suggest that M. ensis may counteract ammonia-N toxicity at the transcriptome level by increasing the expression of genes related to immune stress and detoxification metabolism, and that selected genes may serve as molecular indicators of ammonia-N. By exploring the genetic basis of M. ensis' ammonia-N stress adaptation, we constructed the genetic networks for ammonia-N adaptation. These findings will accelerate the understanding of M. ensis' ammonia-N adaptation, contribute to the research of future breeding, and promote the level of factory aquaculture of M. ensis.

Occurrence and Characteristics of Microplastics in Wild and Farmed Shrimps Collected from Cau Hai Lagoon, Central Vietnam.

This study investigated the occurrence of microplastics (MPs) in the gastrointestinal tracts (GT) and tissues of four common shrimps (including two wild-caught shrimps and two farmed shrimps) collected from a high-diversity lagoon in central Vietnam. The numbers of MP items in greasy-back shrimp (Metapenaeus ensis), green tiger shrimp (Penaeus semisulcatus), white-leg shrimp (Litopenaeus vannamei), and giant tiger shrimp (Penaeus monodon), determined per weight and individual, were 0.7 ± 0.3, 0.6 ± 0.2, 1.1 ± 0.4, and 0.5 ± 0.3 (items/g-ww), and 2.5 ± 0.5, 2.3 ± 0.7, 8.6 ± 3.5, 7.7 ± 3.5 (items/individual), respectively. The concentration of microplastics in the GT samples was significantly higher than that in the tissue samples (p < 0.05). The number of microplastics in the farmed shrimp (white-leg shrimp and black tiger shrimp) was statistically significantly higher than the number of microplastics in the wild-caught shrimp (greasy-back and green tiger shrimps) (p <0.05). Fibers and fragments were the dominant shapes of the MPs, followed by pellets, and these accounted for 42-69%, 22-57%, and 0-27% of the total microplastics, respectively. The chemical compositions determined using FTIR confirmed six polymers, in which rayon was the most abundant polymer, accounting for 61.9% of the MPs found, followed by polyamide (10.5%), PET (6.7%), polyethylene (5.7%), polyacrylic (5.8%), and polystyrene (3.8%). As the first investigation on the MPs in shrimps from Cau Hai Lagoon, central Vietnam, this study provides useful information on the occurrences and characteristics of the microplastics in the gastrointestinal tracts and tissues of four shrimp species that live in different living conditions.

Diversity of Penaeidae at the Mengkudu Bay Waters, North Sumatra, Indonesia

Abstract. Azwar E, Sularno, Waruwu FP, Tarigan MRM, Ulfa SW, Djaingsastro AJ. 2023. Diversity of Penaeidae at the Teluk Mengkudu Waters, North Sumatra, Indonesia. Biodiversitas 24: 1376-1384. Microscopic animals play an important role in the growth of marine biota. Crustaceans are a marine biota group often found in waters and have high economic value. Crustaceans also have a significant role in coral reef ecosystems, contributing around 20% of all invertebrate species. Crustaceans are an important group of microbenthic fauna in coastal ecosystems, ranging from mangroves, coral reefs, and seagrass ecosystems. This present study was conducted from April to June 2022 to identify Penaeidae diversity in Teluk Mengkudu waters, Serdang Bedagai District, North Sumatra Province, Indonesia. Furthermore, it used a purposive sampling method to harvest crustacean species near the waters. An exploratory method was applied with quantitative data collection to select Penaeidae crustaceans from the catches retrieved by fishermen. The tools used in this study were boat, net, fiber, knife, compass, flags, camera, notebook, ice cubes, a thermometer, pH meter, and DO meter. The material used in this study was shrimp caught by fishers. Data collection techniques used interviews and documentation with fishing communities about catching crustaceans at the study site. Data analysis uses the formula diversity, evenness, knowledge richness, and dominance index. Based on the results, Penaeus indicus H.Milne Edwards, 1837 and Metapenaeus ensis (De Haan, 1844) were the two species obtained from the Penaeidae family. The evenness index for P. indicus and M. ensis was respectively highest in June (0.237 and 0.519) but lowest in May (0.203 and 0.510) with a total value of 2.212. Also, the prominent richness index for both species was respectively highest in June (5.762 and 29.371) but lowest in May (4.568 and 27.053). The highest dominance index (D) was measured in May, where the highest D value of P. indicus was 0.003, and the lowest was 0.002. The highest D of M. ensis was discovered in June, namely 0.086, while the lowest, at 0.073, was recorded in May, and in general, both species had a total D of 0.245. Parameters of salinity, pH, temperature, substrate, and oxygen strongly influence crustacean diversity. The parameters measured in the study area included temperature (28?), salinity (20-35 ppt), DO (6.8 mg/L), and pH (6.7).

Effect of the temperature, the wind speed, and the sorbitol concentration on the rehydration ability of shrimp Metapenaeus ensisdrying by using infrared radiation-assisted heating pump

The paper focused on optimising the drying conditions of shrimps Metapenaeus ensis according to Box-Wilson’s multi-factor first-order model based on the objective function of rehydration rate. Shrimp bought in Ca Mau city and dried by infrared radiation-assisted heat pump technology. Sensory, physical (rehydration capacity, impurities, and water activity), chemical (total nitrogen and total protein), and microbiological (total aerobic microorganisms, E. coli) parameters, Coliforms, Salmonella, V. cholerae, and S. aureus) were evaluated on dried shrimp by 3 methods (infrared radiation-assisted heat pump, heat pump, and solar energy). Experiments showed that the equation Y = 57.08 + 1.92*X1 + 1.15*X2 - 1.05*X3 + 0.35*X1X2 + 0.95*X1X3 - 0.625*X2X3 exhibited the correlation relationship between rehydration rate (Y, %) and influencing factors (drying temperature (X1), wind speed (X2), and sorbitol concentration (X3), in which drying temperature (X1) affects the drying time stronger than other factors. Optimal drying conditions were sorbitol 6.3%, drying temperature (57.5oC), wind speed (2.1 m/s), and drying time (5.38 hours). Shrimp dried under optimal conditions has the highest rehydration rate of 57.88%, the shortest drying time, and higher sensory quality and food safety and hygiene than air drying and drying under the sun.

Host-microbiota interactions and responses of Metapenaeus ensis infected with decapod iridescent virus 1.

Decapod iridescent virus 1 (DIV1) has caused severe economic losses in shrimp aquaculture. So far, Researchs on DIV1-infected shrimp have mainly focused on the hemocytes immune response, while studies on the host-intestine microbiota interactions during DIV1 infection have been scarce. This study determined the lethal concentration 50 (LC50) of DIV1 to Metapenaeus ensis, preliminarily determining that M. ensis could serve as a susceptible object for DIV1. The interactions and responses between the immune and intestine microbiota of shrimp under DIV1 infection were also investigated. DIV1 infection decreases intestine bacterial diversity and alters the composition of intestine microbiota. Specifically, DIV1 infection decreases the abundance of potentially beneficial bacteria (Bacteroidetes, Firmicutes, and Actinobacteria), and significantly increases the abundance of pathogenic bacteria such as Vibrio and Photobacterium, thereby increasing the risk of secondary bacterial infections. The results of PICRUSt functional prediction showed that altered intestine microbiota induces host metabolism disorders, which could be attributed to the bioenergetic and biosynthetic requirements for DIV1 replication in shrimp. The comparative transcriptomic analysis showed that some metabolic pathways related to host immunity were significantly activated following DIV1 infection, including ncRNA processing and metabolic process, Ascorbate and aldarate metabolism, and Arachidonic acid metabolism. M. ensis may against DIV1 infection by enhancing the expression of some immune-related genes, such as Wnt16, heat shock protein 90 (Hsp90) and C-type lectin 3 (Ctl3). Notably, correlation analysis of intestinal microbial variation with host immunity showed that expansion of pathogenic bacteria (Vibrio and Photobacterium) in DIV1 infection could increased the expression of NF-κB inhibitors cactus-like and Toll interacting protein (Tollip), which may limit the TLR-mediated immune response and ultimately lead to further DIV1 infection. This study enhances our understanding of the interactions between shrimp immunity and intestinal microbiota. The ultimate goal is to develop novel immune enhancers for shrimp and formulate a safe and effective DIV1 defense strategy.

Effect of Moderate Static Magnetic Field on Membrane Potential of Abdominal Nerve Fiber in Metapenaeus Ensis

Effect of Moderate Static Magnetic Field on Membrane Potential of Abdominal Nerve Fiber in <i>Metapenaeus Ensis</i>

MICROPLASTIC FIBER ACCUMULATION IN SOME WILD AND CULTURED SHRIMP SPECIES

This study was conducted to examine the microplastic fiber abundance and its characteristics in two wild and two cultured shrimp species collected at coastal areas in Hoai Nhon district, Binh Dinh Province. A total of 84 individuals of four shrimp species, Litopenaeus vannamei, Penaeus monodon, Metapenaeus ensis, and Penaeus semisulcatus were collected for analysis. All shrimp specimens were dissected to remove the digestive tracts, which were then treated with 10% KOH to collect microplastic fibers by filtering. The microplastic fiber concentrations varied from 1.96 ± 0.09 to 19.33 ± 10.82 fibers/specimen or 0.20 ± 0.12 to 2.26 ± 1.26 fibers/g of wet body weight. The abundance of fibers in the wild shrimps (Penaeus semisulcatus and Metapenaeus ensis) was higher than in the cultured shrimps (Penaeus monodon and Litopenaeus vannamei). Most fibers observed in the four shrimp species had lengths between 300 and 1500 μm, accounting for 78.72% to 92.82% of the total). White fibers were dominant (30.38%), followed by gray (11.87%), and green (10.60%).

Shrimps distribution and their relationship to the environmental variables in Arafura Sea

Arafura Sea is well-known as the important area for commercial shrimp fisheries in Indonesia. The density of shrimps was highly influenced by their fishing pressure and environmental condition. The objective of this research was to study the distribution of shrimps based on its stock density and their relationship with the environmental variables. Trawling swept area method was used in 16 sampling sites of Arafura Sea during the transition monsoon in 2016. Some environmental variables in bottom layers as shrimp habitat were measured, including chlorophyll-a, dissolved oxygen, depth, salinity, temperature and pH. The results showed that the largest density of shrimps was found in the southern coast of Aru where it has the largest concentration of chlorophyll-a and dissolved oxygen. Among all the environmental variables, Chlorophyll-a was the main variable affected the density of shrimps. Three most dominant species were Penaeus semisulcatus, Metapenaeus endeavouri and Metapenaeus ensis. There was indication of the decreasing shrimp stock in Arafura Sea. The ecosystem-based fisheries management should be developed to rebuild the stock density and to enhance the environmental quality of Arafura Sea.

Routine development of long-term primary cell culture and finite cell line from the hemolymph of greasyback shrimp (Metapenaeus ensis) and virus susceptibility

Long-term and continuous shrimp cell cultures can offer an indispensable tool for studies on the isolation, multiplication and pathogenic mechanism of shrimp causative viruses at cellular and molecular levels. However, they are hard to be developed routinely and continuous shrimp cell line is still unavailable. This can be attributed to a great degree to the unsuitability of medium used. In this study, we have successfully developed a long-term culture condition for the hemolymph cells (or hemocytes) of greasyback shrimp Metapenaeus ensis, designated as MeH cells, by shrimp serum-based and supplements-based optimization of the basic and growth medium. Using the newly developed gelatin-containing optimal basic medium (SBM-12), MeH cell monolayer could be routinely developed and maintained healthily beyond 275 days. In the novel optimal growth medium (SGM-10), the proliferation potentials of MeH cells have been markedly improved, evidenced by the presence of dividing cells in the primarily cultured 30-day hemocytes, suggesting that the mitosis-arrest of MeH cells has been tentatively broken. It was also found that among the 4 types of hemocytes (granulocyte, semi-granulocyte, hyalinocyte and prohaemocyte), the hyalinocytes could not survive after a long-term in vitro culture, but the prohaemocytes could survive well and thus could serve as a good cell source. The addition of gelatin could significantly alter the attachment and cellular morphology of MeH cells and result in a loose attachment and round shape, which made it easy for the cells to be passaged by physical flushing for up to 32 times and a finite shrimp cell line can be developed routinely. Virus susceptibility test showed that the MeH cells cultured in the optimal growth medium were sensitive to shrimp covert mortality nodavirus (CMNV), and obvious cytopathic effects and viral multiplication were detected in the infected cells. In a word, the success in the routine development of long-term primary cell culture and finite cell line from shrimps in this study will greatly facilitate the establishment of shrimp continuous cell lines and studies on shrimp viruses.

Complete mitochondrial genome of Metapenaeus affinis (H. Milne Edwards, 1837) and Metapenaeus ensis (De Haan, 1844)

Penaeid shrimp is one of the marine germplasm resources in tropical and subtropical regions. To better understand shrimp germplasm resources and develop cultured shrimp species, the complete mitochondrial genome of Metapenaeus affinis and Metapenaeus ensis was assembled. The length of M. affinis and M. ensis mitochondrial sequences is 15,957 and 15,943, respectively. Both mitochondrial sequences contain 13 protein coding, 22 tRNA, and two rRNA genes. The GC content of the genome was 34.23% and 34.12% in M. affinis and M. ensis, respectively. Phylogenetic analysis indicated that the M. affinis and M. ensis are closely related, and assigned to a branch of Metapenaeus. We assembled and published the mitochondrial genome sequences of these two species, which will provide important information for the research and utilization of shrimp germplasm resources.

Effects of Spartina alterniflora invasion on the functional groups and niche of benthic crustaceans and fishes in mangrove wetland.

To investigate the effects of Spartina alterniflora invasion on mangrove wetland ecosystem, the benthic crustacean and fish samples were collected using cage nets in Zhangjiang Estuary Mangrove Wetland, Fujian Pro-vince in August 2020, January and April 2021. The five sampling sites included two mangroves (Avicennia marina and Kandelia obovata) sites, two S. alterniflora sites, and one mudflat site. The abundance, biomass, index of relative importance (IRI), Shannon diversity index (H), Pielou evenness index (J), and Margalef richness index (D) were used to quantify the dominant species and species diversity of benthic crustaceans and fishes. The functional groups and niche of dominant species were also analyzed. A total of 37 species, from 2 phyla, 2 classes, 8 orders, and 17 families, were identified across the three seasons. Most of them were warm-water and euryhaline species, mainly carnivorous and omnivorous functional groups. The results of two-way analysis of variance and NMDS showed that the community diversity index of benthic crustacean and fish did not change significantly after the invasion of S. alterniflora compared with mudflat. Functional groups had changed significantly, with the species number of plankton functional groups, carnivorous and phytophagous functional groups being increased. Compared with mangrove sites, the number of species of benthic crustacean and fish in S. alterniflora sites was significantly increased. The spatio-temporal niche breadth of dominant species ranged from 0 to 1.4186, with Liza carinata (1.4186), Bostrychus sinensis (1.0168), Metapenaeus ensis (0.9469) and Exopalaemon carinicauda (0.8922) as the top four species.

Estimating growth from length frequency distribution: comparison of ELEFAN and Bayesian approaches for red endeavour prawns (Metapenaeus ensis)

Abstract Using length frequency distribution data (LFD) is cost-effective for estimating somatic growth in fish or invertebrates as length data are relatively easy to obtain. The recently developed R packages TropFishR and fishboot extend classic ELEFAN (Electronic LEngth Frequency ANalysis) programs and include more powerful optimization procedures and a bootstrap method for estimating uncertainties. Yet, the fundamental functions require users to provide search conditions (e.g. upper and lower limits for each parameter, length-class size, number of length-classes for the calculation of moving average), which can significantly affect the results. In this paper, we compare the ELEFAN approach with a Bayesian approach in analysing LFD, employing both standard and seasonal von Bertalanffy growth functions. We apply both approaches to a commercially valuable but poorly studied red endeavour prawn (Metapenaeus ensis) harvested in Australia's Northern Prawn Fishery. Sensitivity tests on ELEFAN confirm that any change in search settings would affect the results. Simulation studies on Bayesian growth models show that Linf and K can be accurately obtained even with modal progression of only one year-class and using non-informative priors. However, age information, including the theoretical age at length zero (t0), is difficult to estimate and requires LFD from multiple age classes and informative priors. The Bayesian models yield mean parameters of: Linf = 36.56 mm (carapace length), K = 2.74 yr–1, and t0 = -0.02 yr for the males, and Linf = 51.81 mm, K = 1.94 yr–1, and t0 = -0.02 yr for the females. Seasonal oscillation models fit the LFD better, but the improvement is small and the estimated season-related parameters have large variances.