Condition and recruitment of Aristeus antennatus at great depths (to 2,300 m) in the Mediterranean: Relationship with environmental factors

Depth and seasonal trends in the biological condition and recruitment of the red shrimp (Aristeus antennatus) have been analyzed over the slope to 2,233 m in the western Mediterranean. The best biological condition of A. antennatus (gonadosomatic index [GSI]) for mating and spawning occurred at 800–1,300 m in summer, in areas deeper than the fishing grounds distributed between 500 and 800 m. Females moved shallower to feed on the upper slope during periods of water‐mass homogeneity (autumn–winter), increasing their hepatic gland weight (hepatosomatic index [HSI]). Females moved downslope (800–1,100 m) to spawn (high GSI) during periods of water mass stratification (late spring–summer). The HSI of females decreased with depth down the slope in autumn, after the reproductive period. Small juveniles were distributed deeper than 1,000 m, associated with high near‐bottom O₂ levels, low turbidity and high C:N in sediments, implying favorable trophic conditions. This confirms the importance in studying the biology of deep‐sea species over their entire depth range. The progressive warming and increasing salinity of deep Mediterranean waters could provoke a decrease of dissolved O₂ that would affect the life cycle of A. antennatus.     

十足目异尾次目线粒体基因组比较分析及重排研究进展

近年来,线粒体基因组被广泛应用于物种鉴定、群体遗传、系统演化及适应性进化等领域。十足目异尾次目是一类体型介于虾类和蟹类之间高度特化的甲壳动物,在海洋生物系统演化研究中具有十分重要的意义。然而,与短尾次目相比,人们对异尾次目线粒体基因组关注度明显不足;迄今为止对该类群线粒体基因组及基因重排现象仍缺乏系统全面的了解。本研究综述了异尾次目线粒体基因组的研究现状,并对GenBank数据库已公布的26种异尾次目线粒体基因组全序列进行了比较分析,总结了该类群线粒体基因组的基本特征。在此基础上,首次分析了该类群线粒体基因组常见的重排类型及可能的重排机制。比较发现异尾次目线粒体基因组均发生了重排,表现为15种不同重排类型;这些重排事件都可以用复制-随机丢失模型和线粒体内重组模型进行合理的解释。综述还对重排现象在异尾次目系统发育中的应用进行了探讨,以期为异尾次目线粒体基因组进化及系统发育研究提供科学依据。     

Aspects of the benthic life cycle of Penaeus (Melicertus) japonicus Bate (Crustacea Decapoda) along the south-eastern coast of the Mediterranean

Recruitment, migration, growth, longevity and reproduction of Penaeus (Melicertus) japonicus Bate along the south-east coast of the Mediterranean were investigated.Relative population density, measured by catch per unit effort and average body length of the population were used in studying the recruitment, migration and growth of the various age groups.The reproductive state of the females was examined using three parameters: (1) gonado somatic index (ovary weight/total weight); (2) average diameter of ova; (3) morphological appearance of the ova according to a three stage scale.The results showed that P. japonicus migrates from inshore waters to the open sea during its benthic life cycle.Penaeus japonicus is distributed only on sandy substrate. It is suggested that the width of the longshore sandy strip determines the duration of the migration and hence the longevity and maximal growth of the individuals. Rate of migration might be accelerated by increasing density of young age groups near the shore. The estimated life span of each age group is 28–29 months. The maximal average body length of the population is 17 cm for males and 20 cm for females.Penaeus japonicus reproduce from April to November. This period corresponds to the appearance of a new age group about one kilometer offshore.The morphological appearance of the ova, average ovum diameter in each ovary and the female gonado-somatic index (GSI) are related to each other and can serve as a maturation index.Mature females are characterized by body length > 14 cm, GSI > 0.085 and average ovum diameter > 296 μ.     

An Epizootic of Vibriosis in Ecuadorian Pond-Reared Penaeus vannamei Boone (Crustacea: Decapoda)

A massive ephtic of vibriosis, named "sindroma gaviota" (or sea gull syndrome = SGS) by local shrimp fanners, began in November 1989 and continued through May 1990 in nursery and grow-out ponds in a number of shrimp farms located in the Gulf of Guaynquil near Cunyaquil, Ecuador. The level of cumulative mortalities ranged from slight in some ponds to more than 90% in others. Examination of affected shrimp, Penaeus vannamei Boone, led to the isolation of several closely related Vibrio species. The predominant species were identified as Vibrio parahaemolyticus, V. vulnificus , and V. alginolyticus using the API-NFT system. Several of the strains exhibited a transient luminescence and some were positive for urease, an unusual trait for these species. Comparisons of the antimicrobial sensitivity patterns between farm and hatchery isolates from 1989–1990 and hatchery isolates from 1987–1989 indicate that the 1989–1990 pond isolates were not of hatchery origin. The epizootic coincided with the second year of a severe drought in Ecuador. Thus, the discharge of fresh water by the Guayas River was reduced and salinities and relative nutrient concentrations were elevated in the Gulf of Guaynquil. These environmental conditions were ideal for the increased growth of the causative vibrios in the estuarine waters and are believed to be factors that contributed to the 1989–1990 SGS epizootic.     

Sperm maturation and capacitation in the open thelycum shrimp Litopenaeus (Crustacea: Decapoda: Penaeoidea)

Transmission electron microscopy was applied to sperm removed from males and females belonging to Litopenaeus vannamei, L. stylirostris and L. occidentalis. It was discovered that a region named filamentous meshwork (FM), located between the nucleus and the hemispherical cap, develops differently in these three closely related species. In L. vannamei, the FM is synthesized in the male reproductive system, but seems to complete its formation after mating. In L. stylirostris, the FM region was not present in spermatophores collected from males or in sperm from the thelycum. In L. occidentalis, the FM region is fully developed in male sperm. It is suggested that completion of the FM is required for acrosome maturation, and the process continues after mating in some species of Litopenaeus. In vitro induction of the acrosome reaction in sperm from males and females of L. occidentalis demonstrated for the first time that reactivity is significantly superior in sperm cells that have been attached to the open thelycum for some hours, as compared to sperm in males (prior to transfer). This finding suggests that matured sperm cells of L. occidentalis become capacitated to react against egg water after mating.     

Viral-like particles associated with cuticular epithelium necrosis in cultured Litopenaeus vannamei (Decapoda: Crustacea) in Ecuador

A new viral agent was found associated with the endoplasmic reticulum of epithelial cells of the Pacific white shrimp Litopenaeus vannamei (Boone) sampled during mass mortalities. A 40% mortality rate affected nursery and grow‐out ponds during the first 50–60 days of culture, and peak mortality in ponds occurred when shrimp reached 2–4 g. Histopathological changes of affected shrimp showed different grades of necrosis in epithelial cells and, in some cases, other tissues were affected. Transmission electron microscopy (TEM) of columnar cells of the cuticular epithelium showed the accumulation of viral particles, either dispersed in the cytoplasm or in a string‐like or paracrystalline array. These arrays of virions were within membrane‐bound vesicles formed from the endoplasmic reticulum (ER), in orderly arrays on the outer nuclear membrane or along the ER. The virus particles had apparently proliferated in the ER. The virions had an opaque area with an approximate diameter of 20 nm and an electron‐lucent surface layer. The approximate diameter of the non‐enveloped virions was 25 nm. The cytological changes observed are similar to those associated with the Picornaviridae and Nodaviridae families. The histopathology and ultrastructure of a new disease in L. vannamei is associated with the presence of a putative new virus. Until further isolation and characterization is performed, it is recommended to refer to the agent as Litopenaeus vannamei viral‐like particles (LvVLPs).     

Experimental Infections with Baculovirus penaei in the White Shrimp Penaeus vannamei (Crustacea: Decapoda) as a Bioassay

Infections of the virus Baculovirus penaei (BP) have historically impacted penaeid shrimp production in both hatcheries and ponds. BP causes cytopathological alterations and mortality in at least four species, including Penueus vannamei . This study established experimental infections with BP in laboratory-reared P. vannamei . The most useful protocol involved BP infection in third substage protozoea (P₃) induced by feeding virus-contaminated material to rotifers and, in turn, feeding those rotifers to the shrimp larva. Infections were also established by delivering virus-containing brine shrimp to mysis (M) and postlarval (PL) stages. When virus originating from infected adults and juveniles was fed to P₃'s, the shrimp exhibited patent infections with hypertrophic nuclei, polyhedra, free virions, and occluded virions five or six days after being fed the virus. In contrast, when the source of virus material was from bioassay larvae rather than from adults and juveniles, similar patent infections developed in P₃'s by one to two days. A significant mortality in the resulting M's and PL's was associated with the infections with short but not long prepatent periods. In experimentally infected shrimp, examination by light microscopy and transmission electron microscopy revealed extensive viral infection in many cells in the anterior midgut and as many as 80–90% of the proximal and medial hepatopancreatic tubular cells. Free and occluded virions capable of producing disease ruptured into the gut lumen soon after infections became patent. Tests conducted in 1 L Imhoff cones, 160 L spat-cones, and aquaria all produced infections, usually with a prevalence of 100%. The system provides a useful method to detect and assay for infective agents, to amass infective material for research purposes, and to assess the biology of and host response to the virus under different conditions.     

A phylogenetic perspective on biodiversity patterns of Afrotropical freshwater crabs (Crustacea,Decapoda, Potamonautidae)

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Evaluation of two probiotics used during farm production of white shrimp Litopenaeus vannamei (Crustacea: Decapoda)

This study examined the effects of Bacillus licheniformis strain CIGBC‐232, isolated from the gut of shrimp Litopenaeus vannamei and having antagonistic activity against Vibrio harveyi, on the immunity and larval quality of L. vannamei at various ontogenetic stages, in two separate experiments: (1) PL2 to PL17 exposed to the strain CIGBC‐232 under laboratory conditions (2) zoea I to PL8 exposed to the strain CIGBC‐232 and EPICIN 3W probiotics under farming conditions. The first experiment showed that phenoloxidase, peroxidase and superoxide dismutase activities were improved in animals grown with CIGBC‐232 compared to the untreated control. In tests, the resistance to osmotic stress was also enhanced. During the second experiment, animals treated with CIGBC‐232 exhibited significant (P < 0.05) increases in phenoloxidase activity (30–40% higher in zoea I–II, mysis II–III and PL 2–7) and in the respiratory burst (30% higher from PL 2 to 7) as compared to those animals that received EPICIN 3W. There was no significant difference in the lectins and agglutinins (except in PL1, 6 and 7), in peroxidase and superoxide dismutase activities, in the resistance to osmotic stress, nor in the survival rate among treatments. CIGBC‐232 treatment was able to reduce, the level of presumptive Vibrio spp. with respect to EPICIN 3W treatment in the tank water as well as in animals. At the end of both experiments, the growth of shrimp, i.e. weight and length was increased by CIGBC‐232 treatment. This study showed the probiotic effect of CIGBC‐232, which appeared to have a better probiotic performance than EPICIN 3W treatment.     

Postlarval growth of the freshwater prawn, Macro-brachium australiense Holthuis, 1950 (Crustacea: Decapoda: Palaemonidae)

Growth of newly metamorphosed Macrobrachium australiense was monitored in individually vidually held and group held laboratory animals over 28 weeks. A breeding population was also established in a farm dam and the growth of young juvenile F₁ progeny was recorded for a similar time. Up to 26 moults were recorded in this period and intermoult periods increased with age. Prawns held in groups grew better than those held individually. Reproductive maturity was attained by some females in group held laboratory and farm dam animals within the observation period. Length—weight regression equations were calculated for laboratory maintained prawns, i.e., log W = 0.44+ 2.44 log L; log W = 0.45 + 2.46 log L for individually held males and females, respectively; log W = 0.27 + 2.70 log L for group held males and females.     

Digestive peptidases and proteinases in the midgut gland of the pink shrimp Farfantepenaeus paulensis (Crustacea, Decapoda, Penaeidae)

Proteases from the midgut gland of the Farfantepenaeus paulensis juveniles were assessed. Enzyme activity was determined using protease substrates and inhibitors. The effect of pH, temperature and calcium on proteolytic activity was assayed. Caseinolytic activity was analysed in substrate-sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Trypsin, chymotrypsin and leucine aminopeptidase activity was detected. Proteolytic activity was strongly inhibited by the specific trypsin inhibitors. Tosyl-phenylalanine chloromethyl ketone inhibited 59.3% of chymotrypsin activity. The greatest trypsin-like activity occurred at pH 8.0 and 45 °C. Chymotrypsin-like activity reached maximal values at alkaline pH (7.2–9.0) and 55 °C. CaCl₂ did not increase trypsin-like activity, but rather inhibited it at concentrations of 30 (20%), 50 (30%) and 100 mM (50%). The substrate-SDS-PAGE zymogram revealed eight proteinase bands. Two possibly thermal-resistant (85 °C, 30 min) chymotrypsin isoforms were found, which were inhibited by phenyl-methyl-sulphonyl-fluoride. Aminopeptidase activity of enzyme extracts (Arg, Leu, Lys, Phe and Val) and the recommended concentrations of these essential amino acids in penaeid shrimp diets were positively correlated ( P <0.05). Beause protein digestion involves the combined action of different enzymes, adequate knowledge of shrimp digestion and enzyme characteristics is required for the assessment of the digestive potential of different feed sources and development of in vitro digestibility protocols.     

Biological and ecological traits of Bathynomus giganteus and Bathynomus miyarei (Crustacea: Isopoda): Contribution to the conservation of deep-sea in southern Brazil

1. This study aimed to determine biological and distributional aspects of deep-sea giant isopods Bathynomus giganteus and Bathynomus miyarei to assess their extinction risk.
2. Bathynomus giganteus (663 specimens) and B. miyarei (649 specimens) were collected during five research cruises involving 265 h of sampling effort during 32 fishing operations of circular pots, baited traps, ranging from 400 and 1,000 m deep, between 26 and 29°S adjacent to the Brazilian coast.
3. A trend towards larger, sexually mature animals in shallower regions was observed for both species, and depth was the most important environmental variable influencing the animals’ distribution.
4. Bathynomus giganteus were collected between 600 m and 1,000 m depth, while the highest densities of B. miyarei were at shallower depths, between 400 and 600 m.
5. The sex ratio was equal for both B. giganteus and B. miyarei for different seasons, latitudes and bathymetries.
6. The sexual maturity of B. giganteus was estimated at 340–345 mm total length for males and between 280–290 mm for females. Bathynomus miyarei males’ sexual maturity was estimated in the 225–230 mm size class.
7. Bathynomus giganteus showed reproductive activity throughout the year.
8. The longevity of B. giganteus was estimated at 6 years for males and 7.7 years for females. The longevity of B. miyarei was estimated at 9 years for males and 6 years for females.
9. Extinction risk assessment for B. giganteus, which has a greater latitudinal and bathymetric distribution, was evaluated as Least Concern. However, B. miyarei was evaluated in the Data Deficient category.

     

The Effect of Ammonia,Nitrite, and Nitrate on the Oxygen Consumption of Juvenile Pink Shrimp Farfantepenaeus brasiliensis (Latreille, 1817) (Crustacea: Decapoda)

The pink shrimp Farfantepenaeus brasiliensis is native in southern Brazil and is potentially suited for aquaculture. Under intensive culture, the accumulation of nitrogenous compounds results from excretion by the shrimp and from the processes of feed decomposition and nitrification. The objective of this study was to evaluate ammonia, nitrite, and nitrate toxicity effects on oxygen consumption of juvenile pink shrimp. Shrimps (initial weight 0.7 ± 0.15 g) were exposed over a period of 30 days to 50%, 100%, and 200% of the safe levels of total ammonia (TAN = 0.88 mg/L), nitrite (NO₂^? = 10.59 mg/L), and nitrate (NO₃^? = 91.20 mg/L) for the species. The specimens were individually collected and placed in respirometry chambers, where the oxygen consumption was measured over a period of two hours. Throughout the experiment there was no significant difference (p > 0.05) among treatments in terms of survival and growth. The pink shrimp juveniles exposed to nitrogen concentrations of 200% of the nitrite and nitrate safe level showed the highest oxygen consumption (p < 0.05).     

Acrosome reaction of Chinese mitten-handed crab Eriocheir sinensis (Crustacea: Decapoda) spermatozoa: Promoted by long-term cryopreservation

The effects of three media, two temperatures, and fourteen durations of cryopreservation from 0 h to 450 d on in vitro acrosome reaction (AR) of spermatozoa in Chinese mitten-handed crab Eriocheir sinensis (Crustacea: Decapoda) were investigated. The spermatozoa of good quality were obtained from spermatophores by a glass homogenizer in an ice-bath and centrifugation at 4 °C. At 0 h, 2 h, 1 d, 3 d, 15 d, 30 d, 60 d, 90 d, 120 d, 150 d, 180 d, 270 d, 360 d, and 450 d of cryo-storage in Ca²⁺-free artificial seawater, 10% (v/v) glycerol, and 5% (v/v) dimethylsulfoxide at − 80 °C and in liquid nitrogen (− 196 °C), the changes in spermatozoal morphology, the time of beginning AR, and the time of maximum percentage of AR were observed. The relationships of the changes on AR presented with the different media, temperatures, and durations of cryopreservation were speculated. In this study, the cryopreserved spermatozoa all underwent AR in less than 1 h of settlement under room temperature while the percentage of AR in the control was only about 4.9%. Meanwhile, cryopreservation shortened both the time of beginning AR (from 30.11 min of the uncryopreserved spermatozoa to 0 min of cryopreserved spermatozoa on the 30th day) and the time of maximum percentage (from 59.88 min of the uncryopreserved spermatozoa to 0 min of cryopreserved spermatozoa on the 60th day). Whereas the effect of media on sperm cell AR was negligible (P > 0.05), the treatments of spermatozoa with short- and long-term cryopreservation resulted in extremely significant differences in the time of beginning AR as well as in the time of maximum percentage of AR (P < 0.01). The present data indicate that cryopreservation for long or short periods can promote the AR of sperm cells in E. sinensis and physiologically affect the ability to capacitate. It may be that the mechanism of AR in this study is the direct promotion of membrane fusion of the acrosomal cap, or destruction of the proteins inhibiting AR and activation of the proteins promoting AR, by cryopreservation. In addition, the results also show that cryopreservation can protect the spermatozoa because AR can occur in almost all sperm cells cryopreserved for less than 15 d.     

Influence of social factors on the nocturnal activity pattern of the noble crayfish,Astacus astacus (Crustacea,Decapoda) in recirculating aquaculture systems

The social environment plays a major role in the control of growth in many crustaceans, but little is known on the mechanisms involved. Two‐ and three‐year‐old noble crayfish, Astacus astacus are strictly nocturnally active. In the present article, we studied social effects on the pattern of nocturnal activity, represented by the time which the animals spent outside shelters. For this purpose, the activity of groups of uniformly large (‘dominant’) and uniformly small (‘subordinate’) individuals were recorded at different densities both separately and in mixed set‐ups. In crowded laboratory cultures, the presence of larger (dominant) conspecifics was found to reduce the time which smaller (subordinate) individuals spent outside shelters in search of food and feeding by about one‐third. It is suggested that this asymmetric inhibitory effect is an element of the functional chain which ultimately results in an extremely wide variation in individual growth rates of communally reared A. astacus. The relevance of the findings to crayfish aquaculture is discussed.     

Ontogenetic changes in digestive proteases and carbohydrases from the Australian freshwater crayfish, redclaw Cherax quadricarinatus (Crustacea, Decapoda, Parastacidae)

Juvenile redclaw crayfish, Cherax quadricarinatus, show non‐selective feeding behaviour when commencing feeding, but change to a dietary preference for plant material as they grow. This study aimed to find any ontogenic changes in digestive enzymes that might be associated with the change of diet. The enzymes in the digestive tract initially showed high levels of proteases and low levels of carbohydrases, but as the crayfish grew, the levels of proteases fell and the levels of the carbohydrases generally rose, in parallel with the increased preference for plant food. Cellulase was present in all free‐living stages. Dietary requirements of juvenile redclaw are probably quite similar to those of larger specimens.     

Mobilization of organic reserves during ovarian development in a marine penaeid prawn,Parapenaeopsis hardwickii (Miers) (Crustacea,Decapoda, Penaeidae)

The present study furnishes data concerning changes in biochemical constituents of midgut gland and ovary of Parapenaeopsis hardwickii associated with ovarian development. The ovarian index (0I) increased as the ovary developed from stage I (0I = 2.80 ± 0.32) to stage IV (0I = 5.85 ± 0.38) and then decreased suddenly in stage V (0I = 1.20 ± 0.45) following spawning. Associated biochemical parameters (protein, glycogen and fat) show remarkable variation. There was a continuous decline in these parameters in the midgut gland during ovarian development and a similar increase in their concentration in the ovary. The physiological significance of these findings is discussed briefly.     

Selecting and ranking areas for conservation of Aegla (Crustacea: Decapoda: Anomura) in southern South America integrating biogeography,phylogeny and assessments of extinction risk

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