Female Shrimp Research Articles

Examination of the antioxidant effects of linalool and Lippia alba essential oil in the Pacific whiteleg shrimp, Litopenaeus vannamei, subjected to eyestalk ablation

Essential oils are considered to have the ability to minimize the effects of stress during handling in aquatic animals. This study evaluated the anesthetic effects of Lippia alba essential oil and its major compound, linalool, on the antioxidant responses of eyestalk-ablated female shrimp Litopenaeus vannamei. Female shrimp were divided into the following treatments: pure seawater (control), ethanol (9000 μL L−1 of ethanol), 750 μL L−1 of Lippia alba essential oil, 1000 μL L−1 of Lippia alba essential oil, 350 μL L−1 of linalool, and 500 μL L−1 of linalool. The shrimp were sedated for 3 min. The eyestalks were then ablated unilaterally by cauterization (cutting the eyestalk with hot scissors). Biochemical variables were analyzed in the gill, muscle, and hepatopancreas. The antioxidant capacity against peroxyl radicals in the group that received 750 μL L−1 of Lippia alba essential oil was significantly higher in the hepatopancreas and muscle than in the control group, whereas the ethanol group had a higher antioxidant capacity in the gills and muscle than the control group. An increase in the total antioxidant capacity in the hepatopancreas and muscle was observed in the 750 μL L−1 Lippia alba essential oil group, but not in the ethanol group, relative to the control group. A significant reduction in lipid peroxidation in the gills was observed in females treated with 500 μL L−1 of linalool compared to the ethanol group. Linalool and Lippia alba essential oil contributed to the improvement in the antioxidant defense systems of shrimp gills. Overall, the obtained results suggest that exposure to Lippia alba essential oil and linalool may activate certain components of the antioxidant system that exist in the gills and scavenge peroxyl radicals; this in turn may help maintain homeostasis and improve the welfare of eyestalk-ablated female shrimp.

Effect of dietary krill oil levels on the regulation of ovary development in Pacific white shrimp (Litopenaeus vannamei) broodstock

Krill oil is rich in phospholipids and has been proven to significantly promote ovarian development in shrimp. However, the optimal level and related mechanism are unknown. In this study, four isonitrogenous and isolipidic diets were prepared. These diets included different gradients of krill oil supplementation (3%, 6%, and 9%), with no-krill oil serving as a control. Female Litopenaeus vannamei broodstock with stage I ovarian development were fed these diets for 28 days. The results showed that the inclusion of krill oil in the diet had a positive effect on ovarian development in female shrimp, particularly at the 6% supplementation level. This was evident from the significant improvements in the gonadosomatic index and in the 17β-estradiol, progesterone, and methyl farnesoid levels. Moreover, 6% krill oil supplementation facilitated lipid accumulation in the hepatopancreas, promoted the deposition of yolk granules within the oocyte, and significantly enhanced the mobilization efficiency of triglycerides and total cholesterol from the hepatopancreas to the ovary. The upregulation of the serum metabolites choline and phosphorylcholine promotes the synthesis of phosphatidylcholine and triglycerides. Additionally, prostaglandin E2 stimulates the production of ovarian steroid hormones. Acamprosate influences the activity of glutamic acid, potentially leading to a reduction in the secretion of gonadal inhibitory hormones. Multiomics analysis revealed joint enrichment of differentially altered metabolites and differentially expressed genes in pathways involved in arachidonic acid metabolism, cholesterol metabolism, and ovarian steroid synthesis. Additionally, there was significant enrichment in glycerophospholipid metabolism. The expression of the cytosolic phospholipase A2 gene was upregulated in both the lipid metabolism and steroid synthesis pathways. Moreover, the mRNA expression levels of 3β-hydroxysteroid dehydrogenase/delta 5- > 4-isomeras, cytochrome P450 2 L1, and prostaglandin H synthase 2 were also upregulated in the ovarian steroid synthesis pathway. In conclusion, supplementing the diet with 6% krill oil is optimal for promoting lipid metabolism and steroid hormone secretion in female L. vannamei broodstock, thereby enhancing ovarian development and maturation.

Transcriptome profiling of banana shrimp (Fenneropenaeus merguiensis) ovaries and testes: Insights into FoxL2.

The banana shrimp is found in the Pacific and Indian Oceans. Female shrimp are preferred for consumption because they are larger than males. Understanding the mechanism of sex differentiation is important for developing techniques to increase the number of female shrimp for economic benefits. This study investigates the reproductive development of F. merguiensis using transcriptome analysis. Sxl2, dsx, AGH, FEM-1, and Nrg-X2 were classified as essential genes for testes development during the juvenile stage. Several genes were required for both juvenile and adult male development. Additionally, the expression of several genes was shown to be required for juvenile and adult ovarian development, including SOP1, SOP2, Ptgr1, EST, Vgr, Vmol1, and TR-beta A. Interestingly, high levels of FoxL2 expression were observed in the testes, in contrast to previous studies in humans and other mammals. The binding of FoxL2 to the Vtg promoter was demonstrated in silico with the highest relative binding score (RS = 0.89) using the JASPAR program. Knock-down of the FoxL2 gene with dsRNA significantly suppressed FoxL2 at 2, 4, and 6 d. As a result, Vtg expression increased when compared with the control at 2, 4, and 6 d, indicating that FoxL2 plays an important role in Vtg expression in the ovary. Our findings highlight the role of FoxL2 in banana shrimp reproduction and provide valuable information on the genes associated with the F. merguiensis reproductive system.

Population Dynamics of Jinga Shrimp (Metapenaeus affinis) in Samboja Kuala Waters Kutai Kartanegara Regency

Pink shrimp (Metapenaeus affinis) or Jinga shrimp is one of the species caught in the waters off Samboja Kuala. This catch is a valuable commodity in the market. The possibility of exploiting shrimp resources will be jeopardized in an effort to conserve, utilize, and catch high intensity shrimp. This study was conducted from September to December 2022 with the aim of determining population dynamics parameters using the frequency method from carapace length data. A mini trawl was used to collect shrimp in the waters of Samboja Kuala, Kutai Kartanegara Regency. Male and female jinga shrimp have a ratio of 1:2,43. Furthermore, for male and female shrimp, the growth rate coefficient (K) was 0,580 and 14,00, respectively, and the approximated natural length (L) was 145.82 and 160.81. Pink shrimp (Metapenaeus affinis) have natural mortality (M) of 1,113/year, mortality due to capture (F) of 0,516, and total mortality (Z) of 1,630, with exploitation value (E) of 0,316, indicating that they are still at the appropriate level. Herefore, female shrimp peaked in August at 14,6% and males peaked in July 31,81%. The Y/R capability was 0,049/year, and Emax calculated the Y/R relationship with the exploitation rate, which was 0,42.

Sperm Quality Assessment of White Shrimp (Litopenaeus Vannamei) Broodstock using Comet Assay

The quality of sperms is considered one of the factors determining fertilization success of white shrimp, Litopenaeus vannamei. Generally, conventional methods such as sperm count and viability are used for determining sperm quality. Occasionally, the fertilization rate does not correlate with what conventional parameters indicate. Presently, it has become increasingly evident that sperm DNA damage is a potential cause of an unexplained fertilization incompetence of the sperm. Therefore, the present study aimed to determine the feasible application of the comet assay for measuring sperm quality from different male broodstock and to analyze the correlation between sperm DNA integrity and fertilization efficacy of the shrimp. Male and female shrimp sampled from 4 different broodstock ponds were mated in experimental tanks (n = 5). Sperm were collected and subjected to alkaline comet assay. Sperm count, sperm viability, and Gonadosomatic index(GSI) were analyzed for comparison. Viability of the obtained nauplii were recorded and used as larvae production efficiency. The results revealed that nauplius numbers were significantly different among treatments (6.78±1.61×104, 12.18±1.17×104, 16.76±0.97×104 and 21.38±1.14×104 cells/spawn in treatment 1, 2, 3 and 4, respectively), indicating the different fertilization rate between treatments. The average body weights, lengths, and GSIs of broodstock were not significantly different, indicating that the morphological factors were not major causes of the different nauplii production among treatments. The results of comet measurements clearly showed that the levels of comet parameters correlated with the numbers of nauplii obtained from each treatment while the conventional sperm analyses were unable to detect the different quality of the sperm among treatments. This indicates that the degree of sperm DNA damage correlates with the fertilization rate of the shrimp and can be used as a sensitive indicator for determining sperm quality of broodstock shrimp. HIGHLIGHTS Sperm DNA damage is one of the potential causes of low fertilization rate in L. vannamei captive breeding Comet assay is used to assess the degree of DNA damage in a single cell such as shrimp sperm cell using electrophoresis technique Comet assay is more sensitive to detect the sperm integrity among individual L. vannamei broodstock when compared to morphological methods Sperm DNA damage can be used as a sensitive indicator for determining the sperm quality of L. Vannamei GRAPHICAL ABSTRACT

The lack of genetic variation underlying thermal transcriptomic plasticity suggests limited adaptability of the Northern shrimp, Pandalus borealis

IntroductionGenetic variation underlies the populations’ potential to adapt to and persist in a changing environment, while phenotypic plasticity can play a key role in buffering the negative impacts of such change at the individual level.MethodsWe investigated the role of genetic variation in the thermal response of the northern shrimp Pandalus borealis, an ectotherm species distributed in the Arctic and North Atlantic Oceans. More specifically, we estimated the proportion transcriptomic responses explained by genetic variance of female shrimp from three origins after 30 days of exposure to three temperature treatments.ResultsWe characterized the P. borealis transcriptome (170,377 transcripts, of which 27.48% were functionally annotated) and then detected a total of 1,607 and 907 differentially expressed transcripts between temperatures and origins, respectively. Shrimp from different origins displayed high but similar level of transcriptomic plasticity in response to elevated temperatures. Differences in transcript expression among origins were not correlated to population genetic differentiation or diversity but to environmental conditions at origin during sampling.DiscussionThe lack of genetic variation explaining thermal plasticity suggests limited adaptability in this species’ response to future environmental changes. These results together with higher mortality observed at the highest temperature indicate that the thermal niche of P. borealis will likely be restricted to higher latitudes in the future. This prediction concurs with current decreases in abundance observed at the southern edge of this species geographical distribution, as it is for other cold-adapted crustaceans.

Information on the deep-water giant red shrimp Aristaeomorpha foliacea (Risso, 1827) (Crustacea, Decapoda, Aristeidae) population in Antalya Bay (Eastern Mediterranean Sea, South of Turkey) based on the MEDITS protocol

The main aim of this study was to contribute to the current knowledge on the population of Aristaeomorpha foliacea in Antalya Bay located on the southern coast of Turkey in the Mediterranean Sea. Monthly samples were collected between July 2016 and July 2017 from experimental trawl surveys in accordance with the International Bottom Trawl Survey in the Mediterranean (MEDITS) protocol. The abundance index was calculated as 4308.6 N/km 2 and the biomass index as 66.8 kg/km 2. The relationship between total weight (TW) and carapace length (CL) was estimated to be TW = 0.00078⋅CL2.76 for females and TW=0.00049⋅CL2.92 for males. The seasonalized von Bertalanffy growth parameter estimates were CL∞=66.12mm, K=0.43 years −1, tanchor=0.36 years, C=0.63 and ts=0.21 years for females, and CL∞=44.02mmK=0.39 year −1, tanchor=0.30 years, C=0.77 and ts=0.87 years for males. Female shrimps grew slightly faster and reached a larger asymptotic size hence exhibiting a greater growth performance than males. The spawning season was determined as the summer. Recruitment took place in spring, and the sex ratios were found to be 1.29:1 in favor of males. The median size at first maturity was estimated as 37.7 mm CL for females and 30.1 mm CL for males. The annual total mortality rate was 1.66 and 1.41, the annual natural mortality rate 0.57 and 0.72, and the exploitation rate 0.66 and 0.49 for females and males, respectively. The fishing ground for A. foliacea in Antalya Bay is situated within 12 nautical miles off the shore within the territorial waters, thus closed to commercial trawl fisheries between 15 April and 15 September in accordance with the Turkish fishery regulations. The closing period, which coincides with the spawning season and also provides a reduction in the fishing pressure, is clearly of great importance for the sustainability of this species in Antalya Bay.

Symbiotic effect of Bacillus clausii and Galacto-oligosaccharide on growth and survival rates in red cherry shrimp (Neocaridina davidi)

In this 30-day experiment, the effect of probiotics (Bacillus clausii, commercial probiotics: Enterogermina) and prebiotics (Galactooligosaccharides, GOS) on the growth of red cherry shrimp (Neocaridina davidi) has been investigated for 30 days. The trial was conducted with 270 red cherry shrimps (initial weight: 0.24±0.03 g) in 27 plastic tanks (volume 0.01 m3 and area of 0.05 m2) representing 9 groups. Except for the control group, diets were supplemented with either GOS or synbiotics per kg of feed as G1 (1g GOS), G2 (2g GOS), G3 (3g GOS), G4 (4g GOS), G1P (1g GOS+ 1 ml probiotic), G2P (2 g GOS+ 1 ml probiotic), G3P (3 g GOS+ 1 ml probiotic) and G4P (4 g GOS+ 1 ml probiotic). This study showed significantly (P< 0.05) higher growth rate indices of male and female shrimps fed with feed additives groups compared to the control group. The highest final body weight, weight gain, and specific growth rate in male shrimps were recorded from the 2 g GOS+ 1 ml probiotic and 3 g GOS+ 1 ml probiotic groups. Similarly, the highest final body weight, weight gain, and specific growth rate in the female shrimps were found in the G1P and G2P synbiotic groups. Conversely, the lowest final body weight, weight gain, and specific growth rate of both the female and male groups were noted in the control groups. Regarding feed conversion ratio and survival rates of both female and male shrimps, G2P and G3P groups showed significant improvements. Regarding our study's findings, 2 g GOS and 1 ml of Bacillus clausii (commercial probiotic: Enterogermina) dietary synbiotics can be used to improve red cherry shrimp growth rates.

The Multiple Influences of Natural Farming Environment on the Cultured Population Behavior of Kuruma Prawn, Penaeus japonicus.

Recent years have witnessed a tremendous development in shrimp farming around the world, which, however, has raised a variety of issues, possibly due to a lack of knowledge of shrimp behavior in farms. This study focused on the relationship between shrimp behavior and the various factors of natural farming environment through situ surveys, as distinguished from the majority of laboratory studies on shrimp behavior. In the survey, the behaviors of kuruma prawn (Penaeus japonicus) were investigated in the groups of swimming in the water, crawling on the sand, resting on the sand, and hiding in the sand, followed by the quantification of the sex ratio, water quality, density, and light intensity. The results showed the average proportions of resting, hiding, crawling, and swimming activities of 69.87%, 20.85%, 8.24%, and 1.04%, respectively, of P. japonicus. The behavior of hiding, resting, and crawling is significantly affected by the sex ratio of the shrimp (p < 0.05). The proportions of hiding behavior exhibited a negative connection with density and a positive connection with light intensity, while the proportions of resting behavior showed the opposite according to both Pearson correlation analysis and multiple linear regression analysis. The light intensity was the only factor that significantly influenced the swimming behavior, in which the probability of the swimming behavior was reduced from 48% to 5% when light intensity varied from 0 to 10 lx, as determined by the generalized linear model. It could be speculated that P. japonicus prefers a tranquil environment. Female shrimp might exhibit less aggression and more adventure compared to male shrimp. The findings suggested light intensity, followed by density, as the most crucial element influencing the behavior of P. japonicus in the culture environment. These findings will contribute to the comprehension of the behavior of P. japonicus and provide a novel perspective for the formulation of its culture management strategy.

Effects of different sex ratios on the growth and ovarian development of the ridgetail white shrimp, Exopalaemon carinicauda

To study the effects of sex ratio differences on the growth and ovarian development of Exopalaemon carinicauda, and their mechanism, we cultured female shrimps with different numbers of males for five weeks, and measured the growth and ovarian development index of relevant individuals. The results show that: 1) the existence of males reduced the growth rate of females, but significantly improved the ovarian development rate of female individuals. The growth rate of females living with the same sex was significantly accelerated, but their ovarian development rates were relatively slow. 2) Four kinds of communication modes between females and males were tested; i.e., free contact, chemical signals, visual signals, and coexisting chemical and visual signals. Of these four types, free contact improved the ovarian development of females. Under the condition of free contact, the period of the ovarian development cycle was shortened, more nutrients accumulated in the ovary, the amount of sex hormones and Vitellogenin (Vg) increased, and the expression of the gonad-inhibitory hormone (gih) gene tended to decrease. We speculated that testosterone released by males may play an important role in these phenomena. 3) Although the different sex ratios had no significant effect on the growth of females, the speed of ovarian development significantly increased when the female: male ratio was 1:2.

Characteristics of Model Growth And Mortality of White Shrimp (Penaeus merguiensis de Man 1888) in The Estuaria of Bengara, Regency Bulungan

White shrimp is one of the catches of fishermen using fishing gear in the Sekatak Bengara Estuary area, Bulungan Regency which has a fairly high economic value ranging from Rp. 28.000-Rp. 40.000,-. The purpose of this study was to analyze the characteristics of the growth and mortality model of white shrimp (P.merguiensis) in the Sekatak Bengara Estuary, Bulungan Regency. The research method uses descriptive quantitative methods. Sampling of P.merguiensis shrimp used fishing nets with purposive sampling method in the Sekatak Bengara Estuary, Bulungan Regency. The results showed that P.merguiensis shrimp with a total of 2253 samples with 750 male samples with the smallest size 53mm (age 13 days) and the largest size 129mm (aged 62 days), while the female sample was 1503 tails with the smallest size 55mm (age 18 days). and the largest size is 123mm (110 days old) with a sex ratio of 1.0:2.0. The growth model of male and female P.merguiensis shrimp was negative allometry with the male dominant body shape being thin and the female dominant having a fat body shape. The growth model of von Bertalanffy male shrimp has a maximum length of 151.894 mm (451 days old) has a growth speed of 0.03mm/day with a correlation of 64.29% and a female shrimp of 128.01mm (452 days old) has a growth rate of 0.052mm/day with a correlation of 80.07%. The mortality model of male and female shrimp obtained total mortality of 101.17% and 100.9%; catch mortality was 50.75% and 67.81%; natural mortality of 50.41% and 33.09%; exploitation rates of 50.17% and 67.2%, respectively.

A Dynamic Energy Budget Model for Kuruma Shrimp Penaeus japonicus: Parameterization and Application in Integrated Marine Pond Aquaculture.

Simple SummaryIndividual growth models of animals are the basis of ecosystem models, which are important tools for aquaculture management. The lack of mechanistic growth model studies of kuruma shrimp, an important integrated marine aquaculture species, has hindered ecosystem-level aquaculture management. In this study, an individual growth model of kuruma shrimp was constructed based on the dynamic energy budget theory, and the goodness of fit of both parameterization and application was high. The results showed that the model could reproduce the growth of kuruma shrimp in terms of total length and wet weight.Individual growth models can form the basis of population dynamics assessment and ecosystem model construction. In order to provide a basic module for an ecosystem model of an integrated marine aquaculture pond, an individual growth model was constructed for kuruma shrimp (Penaeus japonicus) based on dynamic energy budget (DEB) theory. The model was first parameterized based on a covariation method using the Add-my-Pet (AmP) procedure. The parametric estimation model underestimated the ultimate abdominal length for female shrimp, and the predicted values of other zero-variate parameters were generally consistent with observed values. The relative errors of the predicted and observed values of the univariate data set within three geographical regions showed acceptable goodness of fit. Parameter estimation achieved an overall goodness of fit with a mean relative error of 0.048 and a symmetric mean squared error of 0.066. A DEB model was constructed using the estimated parameters, and the goodness-of-fit indicators (R square, mean bias and absolute and relative root mean square error) showed that the model was able to reproduce the growth of kuruma shrimp in terms of total length and wet weight with high accuracy. The results provide data to support the subsequent development of integrated aquaculture management at the ecosystem level.

Growth, Health, and Gut Microbiota of Female Pacific White Shrimp, Litopenaeus vannamei Broodstock Fed Different Phospholipid Sources.

Phospholipids have an important antioxidant effect on animals. The effects of different dietary phospholipid sources on the growth, antioxidant activity, immunity, and gut microbiota of female broodstock of Pacific white shrimp Litopenaeus vannamei were investigated. Four isoproteic and isolipid semi-purified diets containing 4% soybean lecithin (SL), egg yolk lecithin (EL), or krill oil (KO) and a control diet without phospholipid supplementation were fed to female broodstock of L. vannamei (34.7 ± 4.2 g) for 28 days. The growth performance, antioxidative capacity, and innate immunity of the female broodstock fed phospholipid supplemented diets were improved regardless of sources compared with the control shrimp. The effects on growth and antioxidant capacity in female shrimp fed the KO diet were highest. The innate immunity of female shrimp fed the EL and KO diets were significantly higher than shrimp fed the SL diet. Dietary phospholipid supplementation increased gut microbiota diversity and richness, and the Chao1 and ACE values in the KO group were significantly higher than in the control group. The richness of Proteobacteria, Photobacterium, and Vibrio decreased, whereas the richness of Firmicutes and Bacteroidetes increased in the shrimp fed the KO diet compared with the shrimp fed the SL and EL diets. The interactions of gut microbiota in shrimp fed the KO diet were the most complex, and the positive interaction was the largest among all the treatments. The functional genes of gut microbiota in shrimp fed the KO diet were significantly enriched in lipid metabolism and terpenoid/polyketide metabolism pathways. Spearman correlation analysis showed that Fusibacter had significantly positive correlations with antioxidant activity (total antioxidant capacity, superoxide dismutase, glutathione peroxidase), immune enzyme activity (phenoloxidase and lysozyme), and immune gene expression (C-type lectin 3, Caspase-1). All findings suggest that dietary phospholipids supplementation can improve the growth and health status of female L. vananmei broodstock. Krill oil is more beneficial in improving the antioxidant capacity and innate immunity than other dietary phospholipid sources. Furthermore, krill oil can help establish the intestinal immune barrier by increasing the richness of Fusibacter and promote the growth of female shrimp. Fusibacter may be involved in iron metabolism to improve the antioxidant capacity of female shrimp.

Aspek Biologi Dan Hubungan Panjang Berat Udang Swallow (Metapenaeus Ensis), Udang Putih (Panaeus merguiensis) Dan Udang Dogol (Metapenaeus monoceros Fab.) Di Perairan Aceh Utara

Matang Puntong Seunuddon Village, North Aceh Regency, is a coastal area with great potential in the marine and fisheries sector. One of the potential fisheries in this region is shrimp with high economic value. This study aims to determine several aspects of biology such as identifying species including the relationship between length and weight and sex ratio. The research method used is a simple random sampling method, namely by taking a random sample of shrimp from one basket of fishermen's catch in 1 time sailing. Samples of shrimp were taken 10% of the total catch of fishermen and then measured the length and weighed. Sampling was carried out in April 2021 on the coast of Matang Puntong Village, Seunuddon, North Aceh Regency. The results showed that there were three types of shrimp, namely swallow shrimp with a length range of 95-150 cm, white shrimp with a length range of 12-90 cm, and dogol shrimp with a length range of 59-96 cm with the growth characteristics of both male and female shrimp being negative allometric. Based on the calculation of sex ratio, the ratio of male and female swallow prawns is 1:0.60 with a chi-square test value of 4.354.61, white shrimp is 1:1 with a chi-square test of 4.353.77 and dogol shrimp with a ratio of 1:23 with a chi square test value of 4.350.63.

Genetic identification of Chinese shrimp Fenneropenaeus chinensis post-release in Jinzhou Bay: Implications for management of stock enhancement

The Chinese shrimp (Fenneropenaeus chinensis), one of the important fishery resources in North China, has sharply declined. Artificial propagation and release of F. chinensis have been developed in recent decades in order to supplement wild stocks and improve economic profit. For investigation of the effects of stock enhancement in Jinzhou Bay, we traced this program by sampling 574 female shrimp after spawning and recaptured 293 individuals post-release. Among recaptured individuals, 21 were identified as being hatchery-raised via mtDNA control region and six microsatellite markers identification, accounting for 7.2%, indicating that the hatchery-released juvenile shrimps could survive in the natural environment and contribute to F. chinensis population replenishment in the wild. To address genetic impacts from stock enhancement, we compared the genetic variations between spawners used for enhancement release and local recaptured individuals. High genetic diversities were maintained in F. chinensis stocks, but local recaptured individual stock seemed to exhibit lower genetic diversity. Deviation from Hardy–Weinberg equilibrium and positive values in the inbreeding coefficient in all microsatellite loci and stocks indicated that homogenization and inbreeding may have occurred. More appropriate strategies to restore F. chinensis populations should be discussed for future fishery management.

Histology and External Morphological Assessment on Ovarian Maturation Stages of Wild Female Banana Shrimp, Penaeus merguiensis (de Man, 1888) for Broodstock Selection Purpose.

Study on ovarian maturation stages were carried out using external morphological assessment of ovarian colourations and histological assessment of Oocyte structure for broodstock selection purpose. Stage 1 to Stage 4 of female shrimps broodstock were sampled from Kuala Muda, Kedah, Malaysia. Four obvious colourations of ovary stages were identified which are: yellow (Stage 1), green yellowish (Stage 2), light greenish (Stage 3) and dark green (Stage 4) through the morphological assessment. The Gonadosomatic Index (GSI) showed significant increment as the gonad reach advance stages. Histological assessment of Stage 1 ovary identified perinucleolar oocyte (PO) with small size oocytes. Stage 2 ovary was identified with yolkless oocyte (YO), Stage 3 ovary was identified with late stage of yolky globules and Stage 4 ovary was identified with fully yolky globules. From the results achieved, it can be concluded that the ovarian colourations and GSI can be applied to identify the ovarian maturation stages, meanwhile, the histology assessment is the most precise method to determine the ovarian maturation stages in more details and accurate for each of the ovarian maturation stages.

Atlantic seabob shrimp as biomonitor of Cu and Zn near port activities: is it really a suitable choice?

The trace elements concentration in the muscle of the Atlantic seabob shrimp (Xiphopenaeus kroyeri) caught in coastal fishing highlighted copper (Cu) and zinc (Zn), both related to antifouling systems, as the main elements related to the intensity of port activities of southeast Brazil (~20—to 22ºS). The aim of this study is to analyze if the behavior of Cu and Zn in the muscle of this shrimp species is constant among different sampling sites, verifying if the species is suitable as biomonitor for these elements. The shrimps came from fisheries done in 2017 in Vitória, Anchieta, and Farol de São Tomé, southeast Brazil. After sampling, each individual was categorized for gender and maturity stage, measured, and weighted. Bulk muscle samples were freeze-dried for determination of Cu, Zn, and ratios of stable isotopes of carbon (δ13C) and nitrogen (δ15N). The data analysis verified if the concentration of Cu and Zn in male and female shrimps vary among maturity stages and sampling sites, and how the concentration of Cu and Zn is related to shrimps foraging area and/or trophic position. Both bioaccumulation and growth dilution occurred, but not in the same way for genders and sampling sites, with Cu showing more variability. Relationships between elements and shrimps foraging area and trophic position did not show a clear trend among the sampling sites. Regression models indicated moderate relationships, explaining 51% (Cu) and 60% (Zn) of the association with the foraging area in Anchieta, but up to 8% in Vitória and Farol de São Thomé. For the trophic position, the models explained 33% (Cu) and 34% (Zn) in Anchieta and up to 14% in Vitória and Farol de São Thomé. The results showed that the utilization of this shrimp species as biomonitor of marine coastal environments near port activities to monitoring the levels of Cu and Zn is not a suitable choice, at least in the spatial scale considered by this study.

Linear Dominance Hierarchies in Female Grass Shrimp Palaemon pugio.

AbstractThe grass shrimp Palaemon pugio is an abundant and ecologically important species in estuarine habitats in the northwest Atlantic and is commonly used as an indicator species for environmental contamination, but little is known about its behavior. We examined aggression and dominance in P. pugio by using experimental arenas and groups of five shrimp that were observed an hour at a time for three days in the laboratory. Female shrimp showed high levels of initial aggression that quickly decreased over time, suggesting the formation of a dominance hierarchy. The dominance hierarchy between groups of females appeared linear, with shrimp at five distinct ranks in most replicates and higher-ranked individuals dominating lower-ranked ones. Dominance was significantly correlated with cheliped size but not body size, suggesting that larger chelipeds in female P. pugio may have evolved as a tool to establish dominance, perhaps to gain access to shelter in salt marshes, seagrass beds, or oyster reefs. Grass shrimp are preyed upon by a wide range of estuarine fish, and females are especially vulnerable; so securing access to shelter may provide a major selective advantage, with the dominance hierarchy evolving to save energy through a long-term reduction in fighting over resources.

Influence of 17β-oestradiol (E2) and 17α-hydroxyprogesterone (OHP) on ovarian maturation in Penaeus semisulcatus De Haan, 1844 (Decapoda, Dendrobranchiata, Penaeidae) from the Mediterranean Sea off Alexandria, Egypt

Abstract This study searches to provide appropriate conditions to trigger spawning in Penaeus semisulcatus in aquaculture. The aim was to test the effect of 17β-oestradiol and 17α-hydroxyprogesterone on ovarian maturation and to study the correlation between the different stages of ovarian maturation and hormonal levels in the ovaries, hepatopancreas, and haemolymph. Female shrimps were collected from Ras El-Tin beach and the fishing port to Abu Qir Bay of the Mediterranean Sea off Alexandria, Egypt from June 2018-August 2019. Shrimps were individually weighed and subsequently killed by thermal shock at a maximum temperature of 45°C. Gonadosomatic and hepatosomatic indices were calculated. The correlation between the gonadosomatic and hepatosomatic indices indicates the presence of endogenous and exogenous vitellogenesis. The haemolymph, hepatopancreas, and ovaries were studied by stereo- and electron microscopy. From 15 females in each season the mentioned tissues were isolated for the extraction and quantification of steroid hormones during the different stages of gonadal maturation using radioimmunoassay. An ecdysteroid- and steroid-extraction protocol was applied. Aliquots were collected from the haemolymph to identify 17β-oestradiol and 17α-hydroxyprogesterone by mass spectrometry. Five stages of gonadal maturation were observed. The hepatopancreas was formed by a set of tubules lined with pseudostratified epithelium composed of five cell types, cell E (undifferentiated), cell F (fibrillar), cell B (vesicular), R (reabsorbing), and M (basal) cells. Steroidogenic tissues were small in size and numerous. The ultrastructure of the ovary and hepatopancreas were studied during oocyte development. There was a high concentration of 17β-oestradiol and 17α-hydroxyprogesterone in stages I and II of ovarian maturation, coinciding with the preparation phase for vitellogenesis. A progressive decrease of these steroid hormones occurred during the course of gonadal maturation, and reached its lowest concentration in the spawning period. The ecdysone concentration did not fluctuate in ripe females. Its level increases from stages I-IV of vitellogenesis onward.

Reproductive performance, salinity tolerance, growth and production performance of a cryptic species Penaeus (Marsupenaeus) japonicus

Kuruma shrimp Penaeus (Marsupenaeus) japonicus is a high-value penaeid shrimp in Japanese live fish markets owing to its characteristic colour and flavour. Although this species was believed to be the single species of subgenus Marsupenaeus, the existence of two morphotypes (Form I and Form II) have been confirmed recently. Recent studies classified the native stock from Indian coast as Form II. Four different experiments were carried out to study the reproductive performance, larval survival, salinity tolerance and growout performance of P. japonicus Form II. The reproductive performance experiment was conducted using two treatment groups comprising female shrimp differentiated by the maturity stages (T1–Early maturing and T2–Immature). Female shrimp were unilaterally eyestalk ablated to accelerate the reproductive maturation. Although no significant differences (p > 0.05) were found in fecundity, spawning frequency, number of nauplii and hatching percentage between the treatments, early maturing shrimp had significantly lower (p < 0.05) latency period than the immature group (T1–14 ± 1.37 days vs., T2–25 ± 2.20 days). Additionally, larvae produced from the early maturing group (T1) had significantly higher (p < 0.05) survival rate (37.7 ± 2.7%) at PL (post larvae) stage compared to the immature group (T2–26.82 ± 2.38%). In the salinity tolerance study, PL reared at low salinities (5, 10 g/L) demonstrated similar (p > 0.05) mean body weight (BW) and survival (1.31–1.39 g, 63.3%) compared to shrimp reared at 25 g/L (1.46 g, 79.9%) at the end of 60 days. The 167 days farming trial at stocking density of 50 PL/m2 resulted in productivity of 0.55 kg/m2, with a mean BW of 20.48 ± 0.68 g and 55% survival. Low salinity production performance observed in this study indicates that the native P. japonicus Form II may be physiologically distinct from the other forms/stock elsewhere. The study also concludes the suitability of the species for brackishwater aquaculture.