Usefulness of histological criteria for assessing the adequacy of diets for Panulirus japonicus phyllosoma larvae

Mass seed production depends a great deal on the development of adequate artificial diets, which in turn depends on the development of methods to speedily and reliably assess the nutritional value of experimental diets. This study examined the sensitivity of light histological and ultrastructural criteria to detect differences in the nutritional value of diets for the Japanese spiny lobster, Panulirus japonicus (V. Siebold), phyllosoma larvae. The acceptability of diets, the apparent absorption of lipids and carbohydrates by the midgut gland cells, and the characteristics of various cell types were determined in 43-, 106- and 143-day-old intermoult phyllosoma fed diets of Mytilus edulis (L.) ovary alone (MO) or in combination with Anemia (MO+AR), which so far have given the best results in terms of growth and percentage of metamorphosis into puerulus, and two other diets considered less efficient, viz. Mytilus edulis testis (MT) and Artemia (AR). Acceptability of all diets attained 100% within 10 min of feeding as revealed by observation through the semitransparent cuticle of the larvae. Histological examination of larvae that ingested comparable amounts of food revealed pronounced variation in the absorption of lipids and carbohydrates by the midgut gland cells (AR相似文献   

Molecular attempt to identify prey organisms of lobster phyllosoma larvae

ABSTRACT:   A molecular approach was adopted to investigate the natural diets of palinurid and scyllarid lobster phyllosoma larvae. The central domain of the 18S rDNA gene was amplified using nested polymerase chain reaction (PCR) and genomic DNA extracted from the larval hepatopancreas. The resulting 18S rDNA clones were screened using restriction fragment length polymorphism (RFLP) analysis, and then FASTA homology search and phylogenetic analysis were performed on the nucleotide sequences to identify the source of the eukaryotic organisms. The feasibility of this method was confirmed using the laboratory-reared phyllosoma larvae of the Japanese spiny lobster Panulirus japonicus that were fed either with common mussel Mytilus edulis gonads or with Artemia nauplii exclusively. Among the 804 clones isolated from five wild-caught mid- to late-stage phyllosoma larvae (three palinurids and two scyllarids), 0–132 clones per sample possessed restriction profiles distinct from those of the hosts. The Cnidaria and Urochordata DNA were identified from both the palinurid and the scyllarid larvae, which were thought to be prey animals for the mid- to late-stage phyllosoma larvae.     

Diel timing of molting and metamorphosis of Panulirus japonicus phyllosoma larvae under laboratory conditions

ABSTRACT:   The timing of molting and metamorphosis was monitored for Panulirus japonicus phyllosoma larvae cultured in the laboratory. Larvae cultured under natural light–dark cycle molted synchronously within approximately 1.0 h before and after sunrise, except for a short period after hatching; the timing of molting changed with time of sunrise. When three artificial light–dark cycles were introduced, larvae molted around the start of lighting, irrespective of the light–dark cycles. In the event of a sudden change in the start or end of lighting, molting was regulated by an endogenous rhythm. The start of lighting had a greater impact on the timing of molting than the end of lighting, suggesting that sunrise is probably the critical signal for phase-setting in molting rhythm. Metamorphosis to the puerulus stage occurred within 0.4 h before and 1.2 h after sunset under a natural light–dark cycle, and the timing of metamorphosis was also changed artificially by regulating the end of lighting.     

Larval molting and growth of the Japanese spiny lobster Panulirus japonicus under laboratory conditions

ABSTRACT:   Ten newly hatched phyllosoma of Panulirus japonicus were cultured individually to monitor body length ( BL ) and intermolt period, and 2000 were cultured in groups to sample specimens for measurement of body weight. Phyllosoma were fed with Artemia and mussel gonad; the culture seawater temperature was 24–26°C. The individually cultured phyllosoma showed an increment in body length by the first molt of approximately 0.5 mm, and the molt increment increased to approximately 1 mm at 5 mm BL ; it was constant to 15 mm BL . Thereafter, the molt increment increased exponentially. The duration of the first instar was 6–7 days. Instar duration increased with development up to approximately 2 weeks at the 20th instar (∼16 mm BL ) and then became constant. Of the 10 larvae reared individually, five metamorphosed to the puerulus stage. The entire phyllosoma life ranged from 245–326 days (mean 289.0 days), and the number of instars ranged from 22–29 (mean 26.2). Body length in the final instar ranged from 28.50–33.10 mm (mean 30.280 mm). For the phyllosoma cultured in groups, relationships between BL and wet/dry body weights ( WW / DW , mg) were expressed as exponential equations: WW  = 0.0686 BL ^2.2023 and DW  = 0.0209 BL ^2.1905.     

Population structure of Japanese spiny lobster Panulirus japonicus inferred by nucleotide sequence analysis of mitochondrial COI gene

ABSTRACT:   The mitochondrial DNA sequence for the COI region was determined for 73 Panulirus japonicus individuals collected at three sample locations in Japan. Fifty-one haplotypes, including 69 polymorphic sites without insertion and deletion, were detected, of which three dominant haplotypes were shared among the three sample locations. The nucleotide and haplotype diversities at the three sample locations were in the ranges of 0.009–0.010 and 0.959–0.990, respectively. No significant population subdivision was detected among the sample locations based on the F _st value and net nucleotide substitution rate, and analysis of the molecular variance model ( amova ). There was no characteristic geographic distribution pattern for these haplotypes. These results indicate there is no genetic differentiation between P. japonicus populations in Japan, and support the hypothesis that benthic individuals of P. japonicus are sustained from a population of a common pool of long-period phyllosoma larvae through long-distance larval transport within the Kuroshio Subgyre.     

The release and uptake of metals from potential biofilm inhibition products during spiny lobster (Sagmariasus verreauxi,H. Milne Edwards 1851) culture

Zinc (Zn) and copper (Cu) are strong inhibitors of bacterial biofilms in aqueous solutions, but are known toxins of crustaceans. A new metal application method; cold‐sprayed metal embedment, known to modulate metal release, was tested for its applications in crustacean larval culture systems. Cold‐spray technology allows metal particles to bond to plastics, while modulating metal ion release and biocide activity to the substrate boundary. In this study, Eastern spiny lobster (Sagmariasus verreauxi) larvae (phyllosoma) were cultured in the presence of cold‐sprayed Zn and Cu metal surfaces. Metal loss was monitored gravimetrically on embedded surfaces, assessment of water ion concentrations and analysis of phyllosoma body content were undertaken. Phyllosoma moulting, deformity and mortality patterns were monitored. Cold‐sprayed Zn‐ and Cu‐embedded surfaces were depleted with losses of 0.69% and 31.2% noted respectively. Culture water concentrations of these metals were elevated and accumulation by phyllosoma occurred. Water Zn concentrations of 18.5 μg L^?1 were associated with chronic eyestalk moult deformities; the first report of Zn causing a non‐lethal moult deformity in crustacean larvae. The Cu surface lost a third of its metal mass with a water concentration of 40 μg L^?1 causing acute toxicity and localization of composite granules in the midgut gland. Cu associated mortality was noted by Day 2 of culture with a LD 50 experienced by Day 9. Future work on the use of bioactive metals in aquaculture systems will focus on a range of different metal alloys, and improved modulation of ion release mechanisms through increased particle embedment depth and separation.     

A method of experimental infection of kuruma shrimp larvae, Penaeus japonicus Bate, with baculoviral mid-gut gland necrosis (BMN) virus

Abstract. Infectivity experiments were undertaken by water-borne inoculation of kuruma shrimp, Penaeus japonicus Bate, larvae with BMN virus. Mysis stage larvae were inoculated with the virus by exposure for 2h in sea water containing a homogenized and filtered preparation (450nm) of naturally BMN virus-infected shrimp stored for about 7 weeks at −80°C. Inoculated shrimp stocked in rearing jars were examined to determine whether nuclear hypertrophy of the mid-gut gland epithelial cells characteristic for BMN virus infection could be observed in fresh squash preparations under dark field illumination equipped with a wet-type condenser. Four days post-inoculation at 25–30°C incubation temperature were considered to be satisfactory for the experimental trial.     

Ontogeny of anti-predator behavior in hatchery-reared jack mackerel Trachurus japonicus larvae and juveniles: patchiness formation, swimming capability, and interaction with jellyfish

ABSTRACT:   Laboratory rearing and behavioral observations of larval and juvenile jack mackerel Trachurus japonicus were conducted to elucidate their life-history traits with emphasis on the interaction with the moon jellyfish Aurelia aurita . Jack mackerel were raised from naturally spawned fertilized eggs and they attained 10.3 ± 0.7 (mean ± standard deviation) mm in body length (BL) by 30 days post hatching (dph) and 26.6 ± 1.8 mm BL at 48 dph raised at 19.3–25.0°C. Patchiness (dense aggregation) was confirmed from 5–16 dph (2.9–5.9 mm BL) during the day and from 9–48 dph (4.0–27 mm BL) at night. Cruise and burst swimming speeds were 1.5–1.9 BL/s and 16–24 BL/s, respectively, during larval and juvenile stages, in experimental tanks. Although escape performance from jellyfish was not different between the larvae of jack mackerel and chub mackerel Scomber japonicus , both species showed better survival compared to red sea bream Pagrus major larvae of a similar size. Although jack mackerel were slow in growth, their slow cruise swimming may reduce the chance of encountering predators and fast burst swimming may help escape from gelatinous predators.     

不同温度下刺参对贝类生物性沉积物的摄食与吸收

以常规实验生态方法 ,研究了不同温度下不同规格刺参对贝类生物性沉积物的摄食与吸收 ,得出了实验过程中 ,平均水温为 13.2 0～ 2 2 .30℃时 ,不同规格刺参对贝类生物沉积物平均摄食率 (g/ g .h)依次为大 (0 .0 0 32 4 )、中 (0 .0 0 6 4 8)、小 (0 .0 0 95 9)。另外 ,不同规格刺参对贝类生物沉积物平均吸收率依大(7.32 % )、中 (13.4 9% )、小 (17.6 1% )。其中 ,温度在 15 .13℃时 ,大规格刺参的吸收率达最大 ,为15 .32 % ;当温度上升到 2 3.2 0℃ ,中、小两种规格刺参吸收率达最高 ,依次为中 (2 3.5 6 % )、小 (2 6 .4 9% )。刺参对沉积物中有机物的吸收与利用 ,降低了水底有机物的含量 ,可有效抑制水体有害物质的积累及产生。     

Vertical distribution of jack mackerel Trachurus japonicus larvae in the southern part of the East China Sea

ABSTRACT:   The vertical distribution of jack mackerel Trachurus japonicus larvae was described based on discrete depth sampling using a MTD net system from the surface down to 100 m depth at 13 stations in the southern East China Sea between 27 February and 10 March 2002. Of the 20 782 fish larvae collected, T. japonicus larvae were most abundant, accounting for 37.0% of the total catch. The average abundance of the larvae was 419.0 individuals/10 m², with the average (± standard deviation [SD]) body length of 2.6 ± 0.3 mm (range 1.8–7.5 mm). The larvae were concentrated in the mixed layer, with peak densities in the 10–30 m layer. The average (±SD) weighted mean depth was 21.5 ± 7.8 m. There was no evidence of either diel or ontogenetic vertical migration for the early larvae of <5 mm. More than 90% of the T. japonicus larvae were collected in the water temperature ranging from 21 to 23°C. Vertical profiles of the larval densities and chlorophyll a coincided with each other, which might reflect the abundance of their main prey organisms, copepod nauplii and copepodites, since copepod production is known to be closely related with the chlorophyll a concentration.     

Uptake of dissolved free amino acids by spiny lobster <Emphasis Type="Italic">Panulirus japonicus</Emphasis> phyllosoma larvae

This study examined the ability of late stage (instar XXVI) Japanese spiny lobster Panulirus japonicus phyllosoma larvae to uptake seven l-type amino acids (AAs; aspartic acid, Asp; threonine, Thr; glutamic acid, Glu; glycine, Gly; alanine, Ala; valine, Val; and methionine, Met) from the rearing medium. The time course uptake during incubation for 5 h in solutions containing 1, 2, 5, 10, or 20 μM of each AA was determined using high performance liquid chromatography. There was considerable individual variation in uptake rates and even occasional release of AAs, but larvae showed net uptakes of all seven AAs. Two polar acidic AAs (Glu and Asp) were readily taken up whereas neutral AAs, including three considered as essential for crustaceans (Val, Met, and Thr), had lower uptake rates. Transient releases of AAs by the larvae were common for the AAs with the lowest uptake rates at 1–2 h of incubation. Uptake rates increased with increasing AA concentration but less so for those taken up in larger amounts. Larvae took up AAs to a total of 16.4 μmol/g/h for incubation in the 20 μM solution. The ability to uptake nutrients directly from the medium may be important for the well-being of the larvae.     

Ingestion of artificial diets with different textures as determined by the inert marker ytterbium oxide during culture of early‐stage phyllosoma of the spiny lobster,Jasus edwardsii

Instar 1 and 2 Jasus edwardsii (Decapoda; Palinuridae) phyllosoma larvae were fed an artificial diet formulation (based on fish and mussel) consisting of three different gelatin combinations (firm, 4% inclusion; medium, 2% inclusion; and soft, no gelatin). The diet contained ytterbium oxide (Yb₂O₃; 1% inclusion), an inert heavy metal marker, which was used to confirm diet consumption in instar 1 and 2 phyllosoma. Over a 6‐h feeding period, instar 1 phyllosoma showed a preference for the soft and medium diets as opposed to the firm diet, but this effect was not significant with instar 2. The artificial diets remained palatable over the duration of the experiments, suggesting leaching did not influence diet attractiveness. It is suggested that diets comprising softer food items such as microencapsulated pellets or gelatinous formulated diets and pastes are most suitable for early‐instar phyllosoma. Furthermore, it is also suggested that Yb₂O₃ is a potentially useful marker for ongoing quantitative work on diet utilization in lobster larvae.     

Habitat of pike gudgeon Pseudogobio esocinus esocinus in Nakagawa River, northern Kyushu, Japan

ABSTRACT:   Habitat selection of the pike gudgeon Pseudogobio esocinus esocinus (Cyprinidae) was examined in the Nakagawa River in northern Kyushu, Japan. The study area was 80 m long with two meanders comprising three riffles and two pools, located 20 km upstream from the river mouth. The pike gudgeon were visually counted underwater. Larvae and juveniles were observed in the shallow and slow-flowing water near the shores. Simultaneously, young and adult individuals were observed to inhabit the river bed. Principal component analysis and cluster analysis were applied to estimate the microhabitat selections of the larvae, juveniles and other individuals by using four variables (water depth, current velocity, particle size of substrate and amount of organic matter). The larvae and juveniles inhabited the shallow (<30 cm) and slow-flowing waters (<6.5 cm/s) near the shore; habitat selection was independent of particle size of the substrate and the amount of organic matter present. Young and adult individuals inhabited the river bed independent of the four variables.     

Effects of developmental stage, seawater concentration and rearing temperature on cryopreservation of Pacific oyster Crassostrea gigas larvae

ABSTRACT: For the development of a stepwise cryopreservation technique for larvae of the Pacific oyster Crassostrea gigas , various conditions were examined. Larvae at 9, 12, 15, 18 and 21 h after insemination were cooled at a rate of −1°C/min (seeding at −8°C for 15 min) and then plunged into liquid nitrogen at −35 or −40°C using 1.5 M dimethyl sulfoxide (DMSO) and 250 mM trehalose as cryoprotectants. Among these larvae, 15 h after insemination (the trochophore stage before formation of the shell gland) showed the highest motility and the best external appearance after thawing. Trochophore larvae were cryopreserved in preservation media containing different dilutions (1/4, 1/6, 1/8, 1/10 and 1/30) of seawater. Larvae preserved in the 1/4 seawater medium showed the highest appearance of shelled larvae 4 days after thawing. Trochophore larvae reared in seawater at 21, 25 or 29°C were cryopreserved for 8 months and then reared at 26°C after thawing. Larvae reared at 25°C showed the highest survival rate and normal larval ratio at day 6 after thawing, although larvae reared at 21°C showed the highest rates until day 4. One larva developed at 25°C succeeded to settle.     

Chitosan as a wall material for a microencapsulated delivery system for Macrobrachium rosenbergii (de Man) larvae

Chitosan has been widely accepted as a wall material for preparing microcapsules of various purposes in human medicine. The possibility of using chitosan as a wall material for microencapsulating nutrients and drugs for aquaculture purposes, specifically to Macrobrachium rosenbergii larvae was evaluated in this study. Two types of chitosan-coated microcapsules were prepared using either acetone (MEC-A) or NaOH (MEC-N) as the cross-linking agents. They were compared with a microbound diet relative to total leaching of nutrients and free amino acids (FAA). Among the microcapsules, MEC-N showed the lowest level of total leaching of nutrients (23.3%) during 5 h of immersion in seawater and released 65% FAA after 60 min. During laboratory trials, 75% larvae had accepted the MEC-N capsule. The results of the study suggest that chitosan can be used as a wall material for preparing microcapsules to deliver drugs and nutrients to M. rosenbergii larvae.     

Carbon source and trophic position of pelagic fish in coastal waters of south-eastern Izu Peninsula,Japan, identified by stable isotope analysis

ABSTRACT:   It is important to clarify trophic dynamics in marine ecosystems for management of the fishing ground. Organic carbon sources and trophic position of pelagic fishes in the coastal waters of the south-eastern Izu Peninsula, Japan, were examined on the basis of carbon and nitrogen stable isotope distributions. The δ¹³C of the fishes was mostly distributed from −19 to −16‰ for nektonic fishes (13 species of adults and immatures) and planktonic fishes (10 species of larvae and juveniles), close to the δ¹³C values of particulate organic matter and planktonic decapods. These δ¹³C signatures for the inhabitants of the water column were in contrast with the high δ¹³C values (mainly −16 to −13‰) for demersal fishes of Scorpaeniformes and benthic polychaetes collected in the surf zone. These results indicate that nektonic and planktonic fishes depend on phytoplankton for carbon supply. The δ¹⁵N signatures suggest that the trophic position ranged 3.1–4.5 for the nektonic fishes and 2.9–3.7 for the planktonic fishes, premised on trophic level 3 for larval Japanese anchovy Engraulis japonicus . Thus, planktivorous fishes should be mainly assigned to trophic levels 3 and 4 in this area.     

Fatty acid profiles of spiny lobster (Panulirus homarus) phyllosoma fed enriched Artemia

Three different life stages of spiny lobster larvae (phyllosoma) of Panulirus homarus were fed A1‐Selco‐enriched Artemia in two culture treatments, one with the microalgae Nannochloropsis salina (green water) and the other without the microalgae (clear water) to assess the ability to manipulate their fatty acid composition. Phyllosoma fed with 3‐h A1‐Selco‐enriched Artemia salina attained Stage VIII (5.3 mm) and Stage V (3.4 mm) in 42 days in the green and clear water treatments respectively. The higher content of the essential fatty acids in N. salina (eicosapentaenoic acid, 25.8%; arachidonic acid, 9.5%; and docosahexaenoic acid, 4.2%) in the green water system increased the fatty acid content of the live food Artemia, and ultimately the phyllosoma. In spite of phyllosoma being fed with enriched Artemia in the clear water system, the total polyunsaturated fatty acid content of the early (Stages I–III) and mid stage (Stages IV–V) phyllosoma were significantly smaller (18.8% and 14.6% respectively) (P<0.05) than in the green water system (25.3% and 21.2% respectively). These results indicate the positive role of the microalgae in boosting the essential fatty acid content of lobster larvae.     

Japanese nephropid lobster <Emphasis Type="Italic">Metanephrops japonicus</Emphasis> lacks zoeal stage

ABSTRACT:   Larvae of the Japanese nephropid lobster Metanephrops japonicus hatched in the laboratory were reared at 15°C, and the development and feeding were observed. All larvae hatched at the 'prezoea stage' with no natatory setae on the exopodite of the pereiopods. Without feeding, 50% of prezoea molted into the megalopa stage, having small buds as the exopodite, within 1 h and all molted within 22 h. The megalopa fed with Artemia nauplii, shrimp meat and pelleted food molted into the first juvenile stage with no exopodite after approximately 17 days. The average carapace lengths of prezoea, megalopa and the first juvenile stage were 3.2, 3.6 and 4.4 mm, respectively. The survival rate from hatching to the first juvenile stage was high (90–100%). This lobster may be the only known nephropid species with no zoeal stage.     

The effect of PUFA enriched Artemia on growth, survival and lipid composition of western rock lobster, Panulirus cygnus, phyllosoma

Western rock lobster, Panulirus cygnus, phyllosoma were grown from hatching to stage IV. Larvae were fed with Artemia enriched with a (i) base enrichment (Base) containing 520 g kg^?1 squid oil or tailor made enrichments in which oils high in polyunsaturated fatty acid (PUFA) have been added at the expense of squid oil. These treatments were (ii) base enrichment supplemented with docosahexaenoic acid (DHA) rich oil, (iii) base enrichment supplemented with arachidonic acid (AA) rich oil, or (iv) base enrichment supplemented with DHA and AA (D + A) rich oils. Total survival of phyllosoma to stage IV was high, with no significant difference between treatments (range 12.3–17.5%). By stage IV, the larvae fed the DHA or AA enriched Artemia were significantly larger (3.33 mm length) than larvae fed the Base or D + A enriched Artemia (3.18–3.24 mm length). Phyllosoma were sampled at stages II and III for biochemical analysis. The major lipid class (LC) in all phyllosoma was polar lipid (PL) (88.9–92.4%), followed by sterol (ST) (6.2–9.7%). Triacylglycerol (TAG), free fatty acid (FFA) and hydrocarbon/wax ester were minor components (≤1%) in all phyllosoma samples. In contrast, the major LC in all enrichments and enriched Artemia was TAG (76.3–85.1% and 53.4–60.2%, respectively), followed by PL (11.4–14.8% and 30.6–38.1% respectively). The main fatty acids (FA) in phyllosoma were 16:0, 18:1n‐9, 18:1n‐7, 18:0, AA, eicosapentaenoic acid (EPA) and DHA. Addition of AA, and to a lesser extent DHA, to enrichments resulted in increased levels of those FA in Artemia and phyllosoma compared with the Base enrichment. This was particularly evident for stage III larvae. Comparatively, elevated growth for phyllosoma to stage IV was achieved with DHA and AA enriched diets. Our findings highlight the importance of lipids and in particular essential long‐chain PUFA, as nutritional components for phyllosoma diets.     

Daily age and food habits of Lateolabrax latus larvae and juveniles occurring in the innermost shallow waters of Uwajima Bay, Japan

ABSTRACT:   Daily age and food habits of Lateolabrax latus larvae and juveniles were investigated at two different habitats in Uwajima Bay, western Shikoku, Japan. In the shallow zone at Miura, which contained eelgrass beds, larvae occurred from January and were collected abundantly in March. The size, age, and hatch-date distributions suggested that late-hatched specimens stay longer than early-hatched specimens at this station. On the contrary, in the intertidal flats of the Kunomura River mouth larvae were rarely collected, but juveniles were collected in relative abundance from April. The distributions in the intertidal flats station suggested that specimens had migrated from another location and then resided in the intertidal flats. Spatial and temporal trophic variations increased remarkably with metamorphosis, and thus, the spatial differences in growth rate were considered in relation to the trophic diversity of prey items. Our results suggest that the nursery environment, nursery utilization pattern, and food habits of early life stages of L. latus show remarkable flexibility. From the similarity of these ecological aspects with L. japonicus , which is a closely related species, we suggest the important role of the interspecific competition to the realized niche difference between Lateolabrax congeners.