Artur Pappenheim reported a poor description of the morphology of blood neutrophils from lamprey (Lampetra planeri； adult and ammocoetes) and hagfish (Myxine glutinosa) in Folia Haematologica (volume 8, 1909). Here, we inferred on the morphological characteristics of cyclostome neutrophils observed by Pappenheim based on his descriptions and our previous reports. He recognized neutrophilic leukocytes (mature neutrophils) in lamprey (adult and ammocoetes) and hagfish, and neutrophilic myelocytes (immature neutrophils) in ammocoetes and hagfish. This means the existence of specific granules and azure granules. However, the specific granules were considered as an inner layer (L0) of the striated granule (NG2), and the azure granules outer (L1) layer of the striated granule (NG2). The specific granules (=L0 of NG2) would probably have been stained with triacid (purple), acid dyes, and May-Grünwald·Giemsa (MGG； purple), but not with methylgreen-pyronine (MP). The azure granules (=L1 of NG1a) would also have stained purple with MGG, but negative with triacid, acidic dyes and MP.

The monocytes of lampreys [Lethenteron camtschaticum (adult), L. reissneri (adult), L. hattai (adult, ammocoetes)] were round or oval, low nucleus/cytoplasm ratio, and have striated (two-layered) granules (MoG). The MoG consisted of a basophilic inner layer (L0) and a chromophobic outer layer (L1). The L0 were positive for acid phosphatase, α-naphthyl acetate esterase, naphthol AS-D chloroacetate esterase and Sudan black B. Also, the L0 showed orthochromatic (blue) with toluidine blue. However, ꞵ-glucuronidase, α-naphthyl butyrate esterase and peroxidase were not detected in the monocytes, which were negative for periodic acid Schiff reaction, alcian blue, Sudan III, and oil red O. Kenji Kiyono reported the two types of monocytes (as blood histocytes), real and dubious monocytes, from the blood of hagfish Eptatretus burgeri. He observed both monocyte types in grown-up hagfish, but only real monocytes in undeveloped (details not stated) hagfish. His real monocytes in undeveloped hagfish were speculated as the monocytes of lamprey (mistaking the specimen), and the real monocytes in grown-up hagfish as poorly stained neutrophils. The dubious monocytes of Kiyono were considered as the real monocytes of hagfish.

The author has previously developed and published energy and resource flow models focusing on the post-collection process of marine debris. These models were designed to examine the technical and economic feasibility of establishing businesses with energy systems. One of the previous studies examined the economic feasibility of a microgrid system combining a styrene oil conversion device from drifted styrofoam and a cogeneration system (CGS). The current study focuses on the “biomass gasification furnace and methanol synthesis furnace” technology, which has a proven track record with woody biomass. If this methanol synthesis furnace could be applied to drifting marine debris, it would be an option for providing energy to coastal facilities. In this study, an energy flow model was developed that can easily calculate the energy flow of a methanol synthesis furnace, CGS, and fuel supply system using biomethanol obtained from coastal biomass such as marine debris. If only marine debris is taken into account, the amount of biomass will be insufficient. For this reason, discarded fish and food residues from fishing ports and fish processing plants were also evaluated. Furthermore, this biomethanol can be used together with waste cooking oil to synthesize biodiesel fuel (FAME), enabling various applications including marine fuel. Using this energy model, the potential for energy self-sufficiency for coastal fisheries facilities (fishing ports, fish processing plants, and fishing boats) was calculated. The calculation results show energy selfsufficiency as a function of changes in biomass volume. However, they also found it difficult to be self-sufficient in electricity, heat, and fuel at the same time. Additionally, an optimization model was developed to determine the optimal size of the CGS, demonstrating the potential to improve the energy self-sufficiency of coastal fishery facilities.

In this study, focused on the waste heat energy from seafood processing plant as research to promote the use of unutilized energy. The waste heat energy from seafood processing plant contains large amounts of the high temperature waste gas from the production of fish cake, and the high temperature wastewater from the production of boiled whitebaits and bonito flakes. If these unutilized waste gases and wastewater could be recovered and utilized as the high heat sources, it would lead to significant energy savings. It is assumed that seawater will be used as the low heat source. Seafood processing plants are usually located close to the sea for processing fisheries caught in the sea, and we recommend the use of seawater as the cooling heat source. Therefore, it is necessary to design systems in consideration of the effects on the ocean environment in the area where seawater is discharged, which may lead to significant modification of the ocean environment. If the optimum flow rate of low heat source at maximum net power is identified, the pump power for seawater can be reduced and the flow rate of seawater into the heat exchanger can be minimized as needed, which is expected to reduce the amount of seawater contamination and lead to lower maintenance costs for the heat exchanger. As a result of this study, it was found that the optimum flow rate of low heat source exists for maximum net power and maximum turbine output. The maximum net power was higher when the temperature difference between inlet and outlet of low heat source was higher, while the maximum turbine output was higher when the temperature difference between inlet and outlet of low heat source was lower.

the purpose of this study is to clarify how Company A of fisheries processing and sales Company A in N City, Yamaguchi Prefecture overcame the constraints and challenges of sixth industrialization, such as the existing industrial structure and the limitations of the capabilities of economic entities that many management entities face. In conclusion, with the cooperation of the fishery cooperative in Company A's efforts to become a sixth industrial, the fact that each employee was able to make use of their experience and know-how to overcome the constraints and issues. This is thought to have led to the establishment of the sixth industrialization.

Characteristics of the feeding behavior and relationship between the standard length (SL) and the size of scrape marks of ayu Plecoglossus altivelis altivelis were studied using 123 cultured specimens in aquaria. Feeding behavior was observed individually, 116 specimens (94%) have mouth laterality for feeding. Also, feeding behavior were found two types. The first was eating the algae directly from the shelter in 91 specimens (78%). The second left the shelter and ate the algae after changing direction back to the shelter (22%). One side of the lower jaw when feeding on the acrylic plate side was turned downward and the other side of the jaws was closing. On the scrape marks, 11 to 14 and 11 to 13 level lines were visible caused by the upper and lower jaws and the algae was not scraped between the upper and lower parts. The comb–like teeth groups are arranged as 13 to 14 rows and 12 to 14 rows on the upper and lower jaws, respectively. Therefore, it is suggested that they use almost all of the comb–like teeth groups except the back teeth row on the upper and lower jaws for feeding. The lengths of upper and lower jaws were found to have power regression with the SL, respectively. Also, the relationship between the SL and full width of the scrape marks (FWSM) was： FWSM = 0.3939SL^0.6767 (R^2= 0.8392, 64-212 mm SL).

We investigated the hemolymph CO_2 partial pressure (Pco_2) and bicarbonate concentration ([HCO_3^–]) of the acid–base balance of Mytilus coruscus under resting conditions. Hemolymph collected from the adductor muscle was subjected to the following measurements. Mean values for hemolymph pH and total CO_2 concentration for this state between 18℃ and 23℃ were 7.568-7.601 and 1.54-1.59 mM/L, respectively. Hemolymph Pco_2 and [HCO_3^–] were calculated using the hemolymph pKapp estimated using the relational expression with temperature. Hemolymph Pco_2 and [HCO_3^–] were 1.77-1.83 torr and 1.47-1.50 mM/L at 18℃ and 23℃. To verify Pco_2 and [HCO_3^–], the values were calculated using pKapp obtained by in vitro method (tonometry). Despite the different determination methods, no statistical difference in the obtained values of Pco_2 and [HCO_3^–] were observed. Non-bicarbonate buffer values (ꞵ_NB), which were calculated using the slope of the relational expression between pH and [HCO_3^–] in hemolymph, were 0.42 slykes at 18℃, and 0.54 slykes at 23℃. The hemolymph ꞵ_NB of M. coruscus was in the range of other bivalves, and the hemolymph buffer capacity of the non-bicarbonate buffer system would reflect the Mitilid species.

Identification of leukocytes on tissue sections is important to elucidate the mechanism of swim bladder lesions. To determine the best fixative solution for a koi carp swim bladder, the swim bladders were fixed in 10% formalin, Bouin's, MFAA and Davidson's solution. The swim bladders fixed in MFAA or Davidson's solution were severely detached and twisted, whereas those fixed in 10% formalin and Bouin's solution kept their external shape. However, the majority of the 10% formalin-fixed specimens showed detachment of the tunica interna from the tunica externa under the light microscope. Therefore, Bouin’s solution was determined to be the most suitable fixing solution for the swim bladder. Imprints (head kidney-touched slides glass were fixed with Bouin's solution) and tissue sections of head kidney fixed in Bouin’s solution were stained with Mayer’s hematoxylin and eosin (HE) and May-Grünwald·Giemsa (MGG), and the best staining method for leukocytes identification was investigated. In the HE-stained specimens, identification of leukocytes by staining was difficult. On the other hand, MGG-stained specimens could be identified by staining. Fixation with Bouin's solution and MGG staining was determined to be the most suitable method for leukocytes identification in the swim bladder.

Triacid staining solution (neutral mixture) contains dye complex. Here, we speculate on the structure and characteristics of the dye complex in various triacid staining solutions. It was inferred that the dye complexes in the Ehrlich (methyl green + 2 acid fuchsin, methyl green + 2 orange G, methyl green + acid fuchsin + orange G), Romanowsky (eosin + methylene blue), and Pappenheim (eosin + methylene azure) triacid stains behave as acidic dyes, and that the dye complexes do not dissociate against weakly acidophilic objects, resulting in staining with a complex color (purple). Therefore, it can be said that the objects to which the dye complexes bind without dissociation do not need to be basophilic. When the stained material is highly acidophilic or basic, the dye complex dissociates, and the acidophilic object is stained by the acidic dye and the basiophilic object by the basic dye. The dissociation of dye complexes depends on the degree of acidophilicity and basophilicity of the stained material, and the dissociation depends on the types of dye composing the dye complexes. The dye complex in a triacid stain can be defined as a purple acidic dye in which the bonds between the acidic and basic dyes in the complex can be broken, depending on the acidophilic and basophilic strength of the object.

Previously, we speculated on the staining principle of triacid staining solution (neutral mixture) containing a dye complex. The principle could be explained solely by the relationship between the stained object and the dye complex. We propose here to extend the staining principles of triacid stain to explain the staining principles of other dye mixtures such as May-Grünwald (MG), Giemsa and MG-Giemsa. In a mixture of acidic and basic dyes, the staining characteristics of the object were presumably determined by the degree of stainability (degree of acidophilicity or basophilicity) of the object, the degree of stainability of both dyes (degree of basophilicity of the acidic dye and degree of acidophilicity of the basic dye), and the ratio and concentration of each dye.

‘Hikoshima-haruna’ (Brassica rapa var. narinosa) is a local traditional vegetable in Shimonoseki (Yamaguchi, Japan). The mature leaves are edible and much of the harvest is processed into pickles for consumption in the Shimonoseki area. To expand the consumption of ‘Hikoshima-haruna’, we verified the use of ‘Hikoshima-haruna’ powder in fish paste products as a part of the utilization research. We prepared heated gels (Kamaboko) mixed with 0-10% ‘Hikoshima-haruna’ powder and measured their breaking strength. The Kamaboko containing 1.0-4.0% powder exhibited a bright green color, preserving the characteristics of ‘Hikoshima-haruna’ as a plant with bright green leaves. Although the breaking strength of the two-step heating (30℃ for 30 min followed by 85℃ for 20 min) gels tended to decrease with increasing powder concentration, the 1.0% powder concentration exhibited a slightly greater breaking strength than the other concentrations. Therefore, when applying ‘Hikoshima-haruna’ powder to fish paste products, its use as Kamaboko at a powder concentration of 1.0% was considered appropriate.

The influence of temperature on the hemolymph CO_2 solubility coefficient (αco_2) and the apparent dissociation constant of carbonic acid (pKapp) in Mytilus coruscus was investigated. Mytilus coruscus hemolymph was equilibrated with standard CO_2 gas mixtures to obtain expressions for αco_2 and pKapp as a function of temperature. The relationship between αco_2 and temperature (T) is expressed as follows： αco_2 = 138.247 – 11.253 • T + 0.554 • T^2 − 0.0140 • T^3 + 0.000138 • T^4. The following relationship between pKapp and temperature was found： pKapp = 6.6407 – 0.01589 • T . The parameter units are ℃ for T and µM/L/torr for αco_2. These equations enable estimation of hemolymph αco_2 and pKapp at arbitrary temperatures and simple calculation of Pco_2 and [HCO_3^–].

In 2023, a new seafood cracker named Bakan-Senbei was commercialized in collaboration with National Fisheries University and two private companies. The standout feature of Bakan-Senbei is that it is made from low-utilized/unutilized fish, which contributes to the Sustainable Development Goals. Focusing on this feature, two types of questionnaires（A and B）were implemented to evaluate visitors’ perception of its quality at the Osaka Seafood Show held in February 2024. In questionnaire A, we investigated the potential demand price after providing product information. In questionnaire B, the potential demand price was examined by intentionally excluding only the material information, and then the potential demand price was examined while first excluding material information； then it was examined again after only providing material information and excluding lust time. Interval regression analysis revealed no significant difference between the potential demand prices from the two questionnaires. This result revealed that consumers did not recognize the added value converted into monetary value as perceived quality of the use of low-utilized/unutilized fish. This result indicated that consumers did not perceive the added value of using low-utilized /unutilized fish as translating into monetary value in terms of quality. Conversely, there was a significant difference between the two groups regarding the provision of material information in questionnaire B. This result was supported by the outcome that 21% of respondents raised the rank of potential demand price due to the provision of material information. We estimated the increase price to be 5.5 yen, which was 4.5% of the list price. It was suggested that the added value could be improved by providing important information.

We investigated the effect of temperature on disk abalone Haliotis (Nordotis) discus discus hemolymph CO_2 solubility coefficient (αco_2) and the apparent dissociation constant of carbonic acid (pKapp). The disk abalone hemolymph was equilibrated with a standard CO_2 gas mixture between 10℃ and 20℃, to obtain expressions for αco_2 and pKapp as a function of temperature. The relationship between αco_2 and temperature (T) is expressed as follows： αco_2 = 74.005 - 1.2936 • T - 0.00944 • T^2. And the relationship between pKapp and temperature expressed as follows： pKapp = 6.4675 - 0.08682 • T + 0.003996 • T^2. In these equations, the parameter units are ℃ for T and µM/L/torr for αco_2. The non-bicarbonate buffer values (ꞵ_NB), obtained as a regression coefficient relating pH and [HCO_3^–], were 2.5 Slykes at 10℃, 2.2 Slykes at 15℃, and 3.4 Slykes at 20℃. These equations enable estimation of hemolymph αco_2 and pKapp between temperatures of 10℃ and 20℃.

To induce breeding of the freshwater pufferfish Colomesus asellus, artificial maturation by hormone injection (hCG, 10 IU per gram) and insemination were performed, and subsequent development observed. The rearing environment for the parental fish was freshwater, maintained at 26.0 ± 1.5 ℃ under L12：D12 lighting cycle. Two hormone treatments were applied, one month apart, to two females and four males, ovulation being confirmed 47 hours after the second treatment. Three hundred and sixty-three and 548 eggs with a mean diameter of 1.11 mm (n = 20) were collected from the two females, 334 (92.0 %) and 395 (72.1 %) being fertilized, respectively. The larvae and juveniles were fed with S-type Brachionus sp. fortified initially with freshwater chlorella, followed by Artemia larvae and Chironomid sp. larvae. The pufferfish were reared in a salinity of 7 ‰ for 24 days after hatching, the water then being gradually changed to freshwater over the following 10 days. Two individuals survived for 225 days after hatching, growing to average standard and total lengths of 29.24 mm and 38.72 mm, respectively. The Gonperz growth formulae were as follows：SL：Lt = 29.4075×exp (-exp (-0.02301(t-39.1213))) TL：Lt = 38.51177×exp (-exp (-0.023253(t-41.25841))) Further investigations of rearing conditions, such as salinity, are required to improve the breeding techniques for this species.

On board research were carried out for investigate the quality of fishing boat under the circumstances, which are observed experimentally in ordinary use on the seas. The present research was prepared in the ordinary operation of maintenances in dock. As the results, it was revealed that fuel consumption was reduced remarkably by cleaning bottom of ship hull, propeller and rudder. And in the condition of foul of ship bottom before cleaning, reducing the rotation speed of the main engine capable of largely improving a fuel efficiency, in comparison to the rate of decrease in ship speed.

Viral edema of carp is caused by Carp edema virus and is a major carp disease listed on the WOAH list of emerging infectious diseases. However, an effective experimental infection method that can control virus copy number has not been established. In this study, we compared three experimental infection methods：immersion infection using gill suspensions from diseased fish (immersion method), infection by rearing water from diseased fish (rearing water method) and co-infection method. Cumulative mortality in the immersion groups ranged from 40 to 60%, while that in the rearing water infected and co-infected groups ranged from 80 to 100%. The rearing water method can be used to control the viral DNA copy number and to perform experimental infections when frozen storage is possible. Thus, we performed the same experimental infection using frozen rearing water and found no disease or mortality, indicating that stable experimental infection using the rearing water method is difficult. The immersion method has a lower mortality rate than the other two methods, and it requires a large amount of gill tissue because of the low number of virus DNA copies that can be obtained from the gill tissue. However, it is possible to control the number of virus DNA copies and to preserve the gill tissue suspension by freezing. Therefore, the immersion method was considered the most suitable for stable experimental infection under the same conditions,

Monocytes were observed in the blood of inshore hagfish Eptatretus burgei. The monocytes were round or oval, high nucleus/cytoplasm ratio, and have several round or oval eosinophilic granules, which show dark red or blackish red color when stained with May-Grünwald (MG), Giemsa, and MG-Giemsa stain. The granules were positive for alkaline phosphatase, acid phosphatase, and α-naphthyl butyrate esterase. Also, the granules show metachromatic (reddish purple) with toluidine blue. However, ꞵ-glucuronidase, α-naphthyl acetate esterase, naphthol AS-D chloroacetate esterase and peroxidase were not detected in the monocytes, and negative for periodic acid Schiff reaction, alcian blue, Sudan black B, Sudan III, and oil red O. The monocytes engulfed many yeast particles (zymosan).

Structure and development of eosinophilic granules (EG1) in eosinophils from larva (ammocoetes) of far eastern brook lamprey Lethenteron reissneri were speculated. EG1 is stratified granules (two-layer) and consists of inner eosinophilic layer (L0) and chromophobic outer layer (L1). Three subtypes of EG1 are identified based on the optical artificial image (OAI) of inclusion structure (IS) in L0: EG1a, EG1b, and EG1c. The EG1a had no OAI (probably no IS). The EG1b and EG1c contain IS in L0. The OAI of both EG1b and EG1c were larger than IS. The former was round or oval chromophobic area (OAI-1), and the latter was expanded and rugged (three-dimensional) image (OAI-2) surrounded with OAI-1. EG1a was thought to be a prototype of EG1, which would develop into EG1b and then EG1c.

Neutrophil granules (NG) of West African lungfish Protopterus annectens were classified into two types of stratified [two-layer; inner layer (L0) and outer layer (L1)] granules (type A, NG-A; type B, NG-B). The L1 of NG-A and both layers of NG-B were chromophobic, and L0 of NG-A showed polychromatophilic [eosinophilic or basophilic (orthomethylenophilic or metaazurophilic)]. The L0 of NG-A showed metachromatic (reddish purple) with toluidine blue. On the other hand, L0 of NG-B were positive for acid phosphatase, α-naphthyl acetate esterase, α-naphthyl butyrate esterase and naphthol AS-D chloroacetate esterase. Both types of granules were negative in periodic acid Schiff reaction, alcian blue, Sudan black B, Sudan III, and oil red O. Alkaline phosphatase, β-glucuronidase, and peroxidase were not detected in either granule.

The term “neutrophilic” and “neutrophilic granule” was first introduced by Paul Ehrlich to identify specific granules of major polymorphonuclear leukocytes (neutrophils). He used an original staining method, triacid stain, for this purpose. The staining solution, called “neutral mixture”, which was mixture of acidic dye solution and basic dye solution, with soluble form in water (not neutral dye). In this paper, we speculate the structure and characteristics of the dye complex in the neutral mixture. The dye complex has free acidic groups and is expected to behave as an acidic dye. The dye complex bound to the neutrophilic granules stains the granules with the color tone of the dye complex (purple) because the acid and basic dyes do not dissociate. On the other hand, in the vicinity of the eosinophilic granules and nucleus, the dye complex dissociates into acid and basic dyes, and the former bind to the acid dye and the latter to the basic dye. It was inferred that this dye complex is not formed during staining with stains containing neutral dyes, such as May-Grünwald (methylene blue eosinate), Wright (polychromtic methylene blue eosinate), and Giamsa (containing azure II eosinate).

In aquaculture, leaving dead fish that have sunk to the bottom of the net for a long time causes harmful components from the dead fish body. This risk making other fish in the aquaculture net sick. The early collection of dead fishes is required, but when divers work in the sea, high water pressure and low water temperatures make it difficult for them to work for a long time, and the work efficiency of the entire aquaculture facility is reduced due to the need for manpower. To protect aquaculture fishes from disease, it is useful to install devices and robots to detect and collect the dead fish at an early stage. If the target is small fishes, there is a pumping method. But if the target is medium to large fishes, it is not reasonable. Therefore, we devised a system for collecting dead fishes using AUV(autonomous underwater vehicle) and wire. This report describes the configuration and operation of this system, and conducts simple experiments to confirm its feasibility.

The Tiger Pufferfish (Takifugu rubripes) is a staple in Japanese cuisine, with over ten species of the Takifugu genus found in the surrounding seas. Given that certain parts of the pufferfish are toxic, they are predominantly prepared by trained professionals. Furthermore, species within the Takifugu genus are susceptible to hybridization, leading to an increase in hybrid numbers. However, identifying these hybrids is a challenging and time-consuming task, even for experts. To address this, we developed a transfer learning model using the pretrained VGG16 model to differentiate between pufferfish species. The VGG16 model, commonly used in image recognition, is built on convolutional neural networks. We also implemented Gradient-weighted Class Activation Mapping (Grad-CAM) for visual interpretation of the model. Grad-CAM generates a heat map that highlights the areas focused on by the AI model in the image, allowing us to identify factors contributing to misjudgment and make further improvements. We used seven species from the Takifugu genus (excluding hybrids), and approximately 15 colored images of each species were prepared for machine learning. The results showed that our model was able to distinguish between pufferfish species with relatively high accuracy, although some misclassification occurred among species with similar body patterns. The Grad-CAM results revealed that the model was able to distinguish body patterns, but some misclassifications occurred due to gravel and background objects being recognized as patterns.

Since the construction of class timetables in the university requires a great deal of effort and time, many studies have been conducted in Japan and abroad on the automatic construction of class timetables. Similarly, at the National Fisheries University, labor and time are devoted to the creation of class timetables. Therefore, author aims to conduct basic research on automatic timetable construction with the simulated annealing method in this study. This paper describes the proposed method and algorithm for generating timetables using the simulated annealing method. The generated timetables by the proposed method are also reported.

We investigated the hemolymph oxygen and acid–base status of Akoya pearl oysters, Pinctada fucata martensii, exposed to hypoxic seawater to elucidate the acid–base balance. Akoya pearl oysters cannulated to the anterior aorta for hemolymph collection from the submerged animals showed oxygen and acid–base disturbance of the hemolymph during environmental hypoxia for 24 h (O_2 partial pressure in seawater, Pwo_2 8 torr). The hemolymph O_2 partial pressure (Po_2) decreased from 72.2 torr to 13.6 torr, pH decreased from 7.581 to 7.129, and CO_2 partial pressure (Pco_2) increased from 0.86 torr to 3.31 torr during hypoxia. The hemolymph total CO_2 concentration (Tco_2) and bicarbonate ion concentration ([HCO_3^–]) were 1.93–1.95 mM/L and 1.80–1.91 mM/L, respectively, and there was no statistically significant change between pre-hypoxia and hypoxia for 24 h. When normoxic seawater was resumed after the hypoxia, the hemolymph Po_2, pH, and Pco_2 returned to their initial levels for about 3 h, and hemolymph Tco_2 and [HCO_3^–] gradually increased. These results showed that Akoya pearl oysters undergo hypoxemia and respiratory acidosis in the hypoxic environments for 24 h (Pwo_2 8 torr). In post-hypoxia, most of the disturbances disappeared within 3–24 h, and the increase in hemolymph [HCO_3^–] which was a secondary change compensated for respiratory disturbance.

Effects of water temperature on feeding and growth of the 0-year-old catadromous fourspine sculpin Rheopresbe kazika were studied using 8 different temperatures from 12 to 26℃ for 60 days. At each of the 8 temperatures, 20 fish were reared in aquaria. In the ranges of 16 to 24℃ and 22 to 26℃ the daily growth rate and daily feeding rate, respectively, were higher than the others. Also, the optimal water temperatures were calculated 19.6℃ for daily growth rate and 25.5℃ for daily feeding rate. The optimal water temperature for daily growth rate was lower than that for daily feeding rate. While, feeding efficiency were showed high values in the range from 12 to 22℃. These results indicate that the optimal water temperature range is from 16 to 22℃, and that a water temperature of 12℃ is too low and above 24℃ is too high for sustainable growth during culture of R.kazika.

Two types of stratified (two-layered) granules (type 1, NG1a; type 2, NG2) in the neutrophils of inshore hagfish Eptatretus burgei showed eosin-positive (positive site: outer layer (L1) of NG1a and inner layer (L0) of NG2). In contrast, both eosin-positive sites have been reported to be basophilic. From present result, it is clarified that both sites exhibit as follows: L1 of NG1a, eosinophilic and mataazurophilic; L0 of NG2, eosinophilic, orthomethylenophilic and mataazurophilic. The inshore hagfish neutrophils phagocytosed zymosan particles, in vitro. All blood cells showing phagocytosis were identified as neutrophil.

Neutrophil granules (NG) of adult (mature) far eastern brook lamprey Lethenteron reissneri [L. sp. S (souther form)] were classified into two types of stratified [two-layer; inner layer (L0) and outer layer (L1)] granules (type 1, NG1a; type 2, NG2), like as larva (ammocoetes) of this species. The L0 of NG1a and L0 of NG2 in adult neutrophils were chromophobic, and L1 of NG1a and L0 of NG2 showed chromatophilic. The stainability of those chromatophilic layers with May-Grünwald (MG), Giemsa, or MG-Giemsa were varied [chromophobic, eosinophilic or basophilic (orthomethylenophilic or metaazurophilic)] with a slight difference to larva. As seen in larval neutrophils, these layers were positive for alkaline phosphatase,α-naphtyl acetate esterase and Sudan black B, and some enzymes (acid phosphatase, ꞵ-glucuronidase, and naphthol AS-D chloroacetate esterase) were detected in the L0 of NG2. Alpha-naphtyl acetate esterase was positive in L0 of NG2 of adult neutrophils. Both larval and adult neutrophils lacked peroxidase.

Based on the findings of past literature, we speculated the existence of two types of stratified [two-layer; inner layer (L0) and outer layer (L1)] granules in the neutrophils (granulocytes; blood cells) of amphioxus (Cephalocordata), especially Branchiostoma japonicum. Type 1 neutrophil granules (NG1a) consist of chromophobic L0 and chromatophilic L1. Other type (type 2; NG2) have chromatophilic L0 and chromophobic L1. The L1 of NG1a and L0 of NG2 show metaazurophilic (purple to blackish purple) in Giemsa staining preparation. Ultrastructurally, these two granule types will not be separately identified. These granules contain intragranular particles (granulons, g) in the L0 of granules. At least, three types of granulons (g-1, g-2, and g-3) are recognized in a granule and localized in L0. Two of them form an agglomerate with short rod shape and two layers (inner layer consisted by g-2, and outer layer by g-3). The agglomerate have been considered as tubular structure or microtubule (misinterpretation). Neutrophils of cyclostome (hagfish and lamprey) also have NG1 [NG1a or NG1b (chromophobic L0 and L1)] and NG2. Further, neutrophil granules of cyclostome also contain granulons (without forming of agglomerate).

In order to research the actual operation status of fishing vessels by AIS, an effective extraction method is needed even when vessel name, MMSI, and type of ship information are insufficient. In this study, we analysis on the illegal use of AIS for fishing pole to indicate the location of operations and proposes a method for estimating fishing grounds using AIS buoys. Extracted by Vendor ID and vessel name notation and visualized using the kernel density estimation to show the major fishing grounds. The use of AIS buoys is illegal, but if the reception rate of satellite AIS improves, it may be easier to determine the location of operations and prevent damage to fishing gear.

Growth of immature Lates japonicus in eelgrass (Zostera japonica) beds of the Tomouchi River located at around 4.3 km upstream from the river mouth of the Gokase River, Kyushu Island, Japan was studied by the mark and recapture method and scale reading from September 1998 to March 2004. Newly occurring 0-year-old L. japonicus specimens of 13.9–78.0 mm SL (standard length) in Z. japonica beds of the Tomouchi River in August or September reached sizes ranging 58.8–125.7 mm SL by April and 203.4–232.8 mm SL between October and November of the following year. Monthly changes in specific growth rates of individuals demonstrated that rapid growth months of immature fish were limited to the period of high water temperature (22–28℃) from June to October. Also, it was supposed that the large-sized fish of the 0-year-old fish migrated away from Z. japonica beds after December, however a few fish remained in Z. japonica beds until the following November.

Viral edema of carp (VEC) caused by the carp edema virus (CEV) causes economic losses for Japanese koi farms. In this study, we investigated the infectivity and pathogenicity of a domestic CEV isolate (genogroup IIa) in koi carp, common carp and goldfish. The challenge test consisted of 9 groups (n = 15):3 groups each of koi carp, common carp, and goldfish, at 15, 20 and 25℃. These groups were challenged with CEV (3.0×10^3 copies/µL) in duplicate. All koi carp died in the 15 and 20℃ groups, but all survived in the 25℃ group. The surviving koi carp in 25℃ groups showed high PCR positive rates of 66.7 and 73.3%, with VEC histopathological changes observed. For the common carp, 1 and 2 fish died in the 20℃ groups, but no deaths or VEC symptoms were observed in the 15 and 25℃ groups. In all common carp groups, PCR-positive fish were observed along with histopathological changes. For all goldfish groups, no deaths or VEC symptoms were observed. As with the common carp, PCR-positive fish were found in all goldfish groups, yet no VEC histopathological changes were detected. These results demonstrate infectivity of this CEV strain in koi carp, common carp, and goldfish, but low pathogenicity in common carp and goldfish.

Embryonic development in giant cuttlefish Sepia latimanus was studied using eggs laid from broodstocks reared in captive condition. 26 embryonic stages were examined in this study and the detail process of organ development was clarified under microscope observation. Blastdisc was visible at the animal pole on the yolk at 2.5 hours after fertilizaton (HAF). The first cleavage occurred at 8.6 HAF. Then embryo developed to the morula stage at 22 HAF. Almost surface of the egg was covered with blastoderm at 10 days after fertilization (DAF). Primordia of main organs such as arms, mouth, mantle, funnel, optic vesicle, gills, statocyst, lens and optic ganglion were formed till 14 DAF. At 15 DAF calcification began in the first striation on the shell. Primordium of the shell became visible at 18 DAF. The number of striations on the shell reached to 5, 9 and 14 at 26, 32 and 40 DAF, respectively. Embryo needed 45 days for hatching. Newly hatched larva was 14 mm in mantle length and had 18 striations on the shell. The process of embryonic development in S. latimanus was very similar as S. lycidas, S. esucurenta and Sepiella japonia. S. latimanus is characterized with large newly hatched larva in Japanese sepiids. It was revealed that the large yolk of S. latimanus induces the growth of the body over a long period in the embryonic stage.

We investigated the hemolymph oxygen and acid–base status of akoya pearl oysters, Pinctada fucata martensii, exposed to air for a short time (4 h) to elucidate the acid–base balance and CO_2 dynamics. The hemolymph O_2 partial pressure (Po_2) in air-exposed akoya pearl oysters decreased from 88.7 torr (mean value) to 29.4 torr at 1 h, and the low Po_2 continued for the next 3 h during air exposure. The hemolymph pH decreased from 7.586 to 7.082 during air exposure for 1 h and reached 6.851 at 4 h. The hemolymph CO_2 partial pressure increased from 0.9 torr to 4.4 torr at 1 h and reached 7.3 torr after 4 h of air exposure. The hemolymph bicarbonate concentration and calcium ion concentration at 0 h (control) were 1.9 mM/L and 9.0 mM/L, respectively, and these properties did not significantly change during air exposure. From these results, it was determined that the akoya pearl oysters had hypoxemia caused by hypoventilation at an early phase of the short-term air exposure. The akoya pearl oysters inhibited the discharge of CO_2 by hypoventilation, and respiratory acidosis was caused due to the excessive accumulation of CO_2. Bicarbonate was not mobilized from the shell valve into the hemolymph during the short-term air exposure.

We aimed to clarify the microhabitat preferences of Atyidae shrimps in the middle to upper reaches of the Hiwasa R. , Kitagawatidani R. , and Mugi R. , Tokushima Prefecture, southern central Japan. Relationships between the shrimp abundance and physical environmental variables were surveyed at six sites in 2011 fall and 2012 spring by setting 5-m line transects delineated with ten consecutive 50-cm quadrats along the riverbank. The dominant shrimp species collected from the riverbanks were Caridina multidentata, Paratya compressa and Neocaridina denticulata. C. multidentata was shown to prefer loose boulder or cobble beds with interstices. When interstices were scarce, the shrimps were found inhabiting among the vegetation. P. compressa was shown to prefer vegetation and boulder or cobble bed in pools. N. denticulata tended to prefer vegetation in darker, gently-flowing areas. Our results insist that the three shrimp species segregate microhabitat under base-flow conditions, but flow reduction may cause microhabitat overlap between C. multidentata and P, compressa.

In aquaculture and fixed-net fishing, fishing nets need to be fixed in the water for a long period of time. Therefore, attached organisms such as shellfish, algae, and parasite eggs easily stick to the nets, making periodic cleaning indispensable. A common method is for divers to dive into the water and clean the nets directly with their hands. However, this method is dangerous because it can be fatal to divers due to high water pressure and low water temperature. Therefore, this study considered the possibility of using underwater robot to clean fishery nets in place of divers to avoid these dangers. A mobile mechanism that can move freely along the sides of fixed fishery net in the water has already been developed in this laboratory. In this study, we propose the cleaning system using autonomous robots that automatically cleans aquaculture nets underwater and the charging station using coils for wireless power supply. This robot and a charging station will be installed on the aquaculture nets, and the robot will be driven periodically to clean the nets underwater with less labor and in a safe manner.

We investigated the oxygen and acid–base status of the densely lamellated oyster, Ostrea denselamellosa, during air exposure for 24 h. The hemolymph O_2 partial pressure decreased from 68.0 torr (mean value) to 52.1 torr during air exposure for 18 h, and reached 42.1 torr after 24 h. The hemolymph pH decreased from 7.579 to 6.798 at 18 h and to 6.361 at 24 h. The hemolymph CO_2 partial pressure increased from 1.30 torr to 40.9 torr at 24 h during air exposure. The hemolymph bicarbonate concentration increased from 1.36 mM/L to 2.81 mM/L at 24 h. The hemolymph calcium ion concentration increased from 8.2 mM/L to 10.9 mM/L at 24 h. From these results, it was revealed that the densely lamellated oysters caused a progressive hypoxemia by hypoventilation of the gill during air exposure. The densely lamellated oysters were inhibited from releasing CO_2 from the gill by hypoventilation, and respiratory acidosis was caused due to the accumulated CO_2. The densely lamellated oysters exposed to air for a long time developed metabolic acidosis due to anaerobic metabolism partially compensated with mobilized [HCO_3^–] from the shell valve.

To improve breeding techniques for aquarium freshwater pufferfishes, hormone injection (hCG, 10 IU per g)-induced maturity and insemination of Auriglobus modestus from Thailand were undertaken, and morphological development of eggs and early stage larvae observed. Artificial insemination was performed two to five days after hormone injection. Although no fertilized eggs resulted from artificial insemination utilizing a wet (freshwater) method, an isotonic (sodium lactate ringer solution) method produced 458 fertilized eggs out of 787 eggs (fertilization rate 61.7%) spawned by one female, although only 8 larvae (1.7%) eventually hatched. Eggs were oval [long axis 2.05 ± 0.06 mm, short axis 1.68 ± 0.06 mm (n = 5)], translucent, demersal, and adhesive, and contained a number of small yellow oil globules. Oval eggs are unusual among pufferfishes, although common in the genus Chonerinos, an indication of the genetic closeness of the latter and Auriglobus, but also suggesting ecological similarity. The eggs hatched after 2 days, larvae one day after hatching [4.54 ± 0.34 mm NL (n = 9)] having a large yolk sac. However, the mouth remained unopened, the optic vesicle uncolored, and the pectoral fin membrane undeveloped, except for small knob-like rudiments. Seven days after hatching, larvae [5.22 ± 0.10 mm NL (n = 3)] had lost the yolk sac and acquired rudimentary soft rays in the pectoral, dorsal and anal fins. All larvae died after eight days. DNA barcoding comparisons (COI gene, 652 bp) of several pufferfish genera indicated a close genetic relationship of Auriglobus and Chonerhinos, being nested in the same clade.

An unusual instance of biting behavior by the pufferfish Arothron meleagris, possibly related to spawning behavior was observed during low tide of new moon spring tide while scuba-diving off the Maldives Islands. Multiple males were following, biting and clinging persistently to a female. Subsequent internet searches revealed that similar biting behavior was common among several congeners, possibly being a characteristic spawning-related behavior of the genus.

Recently overbrowsing by fish in cultivation of the wakame Undaria pinnatifida has become problematic and the black scraper Thamnaconus modestus is suspected of the feeding damage for the cultured U. pinnatifida as well as a few herbivorous fishes and the Japanese black seabream Acanthopagrus schlegelii, but aspects on feeding behavior and bite scars of the species are extremely limited. We examined characteristics of bite scars left on thalli of the cultured U. pinnatifida by feedng of T. modestus in a tank experiment. The species showed active feeding behavor of the cultured U. pinnatifida and conspicuously consumed juveniles rather than adults. Bite marks left on blades were categorized into three shapes of arc, ellipse and serration and particularly the ellipse-shaped bite mark is characteristic of T. modestus, unknouwn for other overbrowsing fishes. Additionally cut surfaces of those bite marks were edged with irregular gentle concaves. The shape of bite marks on the thalli was thought to be useful for identifying the fish species that caused the feeding damage of the cultured U. pinnatifida.

Two types of stratified [two-layer； inner layer (L0) and outer layer (L1)] granules were observed in the neutrophils (neutrophil granule, NG： type 1, NG1a； type 2, NG2) of larva (ammocoetes) of far eastern brook lamprey Lethenteron reissneri collected in a tributary of the Koyagawa River in Yamaguchi Prefecture. The NG1a consisted of chromophobic L0 and chromatophilic L1. On the other hand, the NG2 had chromatophilic L0 and chromophobic L1. The L1 of NG1a and L0 of NG2 showed a variety of colors [eosinophilic or basophilic (orthomethylenophilic or metaazurophilic)] depending on the staining conditions. These layers were positive for alkaline phosphatase, α-naphtyl acetate esterase and Sudan black B. Some enzymes, such as acid phosphatase, ꞵ-glucuronidase, and naphthol AS-D chloroacetate esterase were detected in the L0 of NG2. The neutrophils lacked α-naphtyl butyrate esterase and peroxidase.

Two types of stratified granules (two-layer) were observed in the eosinophils (eosinophil granule. EG： type 1, EG1； type 2, EG2) of larva (ammocoetes) of far eastern brook lamprey Lethenteron reissneri collected in a tributary of the Koyagawa River in Yamaguchi Prefecture. The EG1 consisted of inner eosinophilic layer (L0) and chromophobic outer layer (L1). Dark (low light transmittance) inclusion structure (IS), which was various size and morphology (round, oval, rod, or spindle), was observed in the L0 of many EG1 (only one IS in a EG1). The IS was found in the cytochemical staining preparation, but not in the preparation stained with May-Grunwald (MG), Giemsa and MG•Giemsa. Therefore, recognition of IS was affected with the eosin-stained L0 of EG1. The EG1 classified into three subtypes (EG1a, EG1b and EG1c) based on the optical artificial image (OAI) of IS in L0. The EG1a had no OAI (probably no IS). The OAI of both EG1b and EG1c were larger than IS. The former was round or oval chromophobic area (OAI-1), and latter was expanded and rugged (threedimensional) image (OAI-2； chromophobic； round, oval, or rod). The EG1a may be prototype of EG1. The EG1 showed no positive reaction by various cytochemical stains. The EG2 had chromophobic inner layer (L0) and basophilic (orthomethylenophilic) outer layer (L1). Some enzymes (alkaline phosphatase, acid phosphatase, ꞵ-glucuronidase, α-naphtyl acetate esterase, naphthol AS-D chloroacetate esterase) were detected in L0 of EG2. The eosinophils lacked α-naphtyl butyrate esterase and peroxidase.

Mentaiko, a seasoned cod roe, is one of the main food products in produced from the ovary of Walleye Pollock in Japan. Walleye Pollock roe is predominantly used in the preparation of Mentaiko, with limited other applications. This study showed the processing procedure for an edible film from the Walleye Pollock roe. A few conditions were identified wherein the film could be prepared during processing of the roe. In the first step, water-soluble proteins were extracted from roe samples employing a pH 12.0 phosphate buffer. The pH of this mixture was subsequently adjusted to pH 6.0, mixed with 1.0% transglutaminase and heated at 70℃ for 20 min. Finally, the product was dried in silicon cases suitable for the preparation of edible films. Evaluation of the dried film indicated some improvement in terms of flexibility compared to similarly produced films. During the evaluation of various film-forming solutions, an increase in the amount of surface hydrophobic groups and/or surface sulfhydryl groups was associated with an increased film production. We showed that the edible film can be produced from the proteins of Walleye Pollock roe.

This study examines the roll of Ube municipality to build collaboration with sales businesses in local fishery sector. Ube city adopted “Evidence－Based Policy Making” to make the next fisheries promotion plan. They conducted questionnaire survey to the local fishery sector and customers and made the first draft of the promotion plan according to the result. Members of the committee were also the local fishermen, distributers and representative from the tourist industry and they discussed and understood the present situation and problem of the community and became awareness of the necessity of their new action. Thus they could take the first step to build a cooperative business relationship among local fishery sector.

In the United States, the Korean War (1950–1953) has long been known as the “forgotten war.” However, the war was a watershed for racial minorities in the U.S. military. The U.S. racial policy was changed drastically after U.S. president Harry S. Truman signed Executive Order 9981 in 1948. This study analyzes the military service of Japanese American Nisei (the second generation) who served in the Korean War. The goal of this study is to clarify the transitions of social status of Nisei before and after their service. The paper highlights the Nisei’s motivation to serve in the military, using semi-structured interviews of Californian veterans that I conducted from 2008 to 2019. Most were Nisei and had U.S. citizenship as their birthright. However, their citizen status was insecure even in the fifties, and racial discrimination prevented them from obtaining adequate employment or college education. The Korean War GI Bill benefits definitely supported them after they returned from the battlefield. In this sense, military service in the Korean War became a pathway to success in the post-internment era for Nisei, yet it also revealed their unstable social status. This paper categorizes their motivations to serve from three elements ： socioeconomic reasons, honor and dignity as U.S. soldiers, and their loyalty and patriotism for the United States. The multiple voices of my interviewees shows that while their difficult situations were certainly critical elements among their motivations for service, their various experiences still should not be considered as simply monolithic.

We investigated the oxygen and acid–base status of the noble scallop Mimachlamys nobilis during air exposure for 24 h. The hemolymph of noble scallop was collected from the adductor muscle, and O_2 partial pressure (Po_2), pH, CO_2 partial pressure (Pco_2), and bicarbonate ion concentration ([HCO_3^–]) were examined during air exposure. Hemolymph Po_2 decreased from 69.5 torr (mean value) to 46.3 torr during air exposure for 6 h, and reached to 19.0 torr after 24 h. The hemolymph Po_2 of air-exposed noble scallops decreased gradually and caused progressive hypoxemia by hypoventilation of the ctenidium. Air-exposed noble scallops showed a reduction in pH and elevation of Pco_2 and [HCO_3^–] of the hemolymph. In air-exposed noble scallops, the hemolymph pH decreased from 7.460 to 7.045 at 6 h and to 6.348 at 24 h. The hemolymph Pco_2 increased from 1.30 torr to 5.05 torr at 6 h and to 56.6 torr at 24 h during air exposure. The [HCO_3^–] increased from 1.26 mM/L to 1.88 mM/L at 6 h and to 4.19 mM/L at 24 h. N32From these results, in the first 6 h of air exposure, noble scallops mainly underwent respiratory acidosis by excess accumulation of CO_2 due to hypoventilation. Meanwhile, after 24 h of air exposure, noble scallops showed mainly metabolic acidosis partially compensated by mobilized [HCO_3^–] from the shell.

In the fishery industry, fishing nets tend to be in the water for a long time. Therefore, there is a possibility that the fishing nets will be broken by marine animals or “Kyucho”； it stands for the violent currents caused by tides or typhoons. It is necessary to repair fishing nets as soon as possible for preventing fishes from escaping to outside of the fishing net. However, a great deal of labor is required to lift and repair fishing nets. In addition, high water pressure and low water temperature may make it difficult for divers to work underwater. Therefore, underwater robot is useful to work instead of divers under such severe situations. The author suggests development of the underwater ROV (Remotely Operated Vehicle) type robot that can move on fishing net with magnet tires and repair the net using manipulators. This paper introduces the development and performance evaluation of the underwater robot using magnetic mobile mechanism.

In this research, aiming at efficient cooling of the locally concentrated heating part of the electronic element, a new concentric circular microchannel plate that can efficiently cool the CPU is designed in consideration of the heat generation characteristics of the CPU. Then, we conducted an experiment on heat transfer when water was used as the refrigerant for this new microchannel plate, and grasped the basic heat transfer characteristics. Furthermore, by comparing the results with the straight microchannel plate having a simple structure, the heat transfer promotion of the concentric microchannel plate was examined. By using a concentric microchannel plate, the temperature at the center of the heater can be maintained at about 25℃, and even when compared with a straight microchannel plate, the temperature rise can be suppressed by about 8 to 23℃. The heat transfer coefficient of the concentric circular microchannel plate is 6 to 8 kW/m^2 K, which is almost constant, and about four times higher than the heat transfer coefficient of the straight microchannel plate at the same heat quantity and the same flow rate. In addition, the research results were compared with the previously proposed experimental correlation equation for single phase forced convection laminar heat transfer of straight microchannnels.

Learners of thermodynamics learn a basic thermodynamic state quantity “entropy” which is challenging to understand owing to multiple reasons. First, entropy is explained using multiple defining equations； intuitively understanding the meaning from the equations can be difficult. Second, entropy is often explained in terms of “clutter” and “disorder” of energy； however, the correspondence between these concepts and the defining equation is not obtained intuitively. Therefore, in this study, we considered a virtual lattice space in which gas molecules are arranged and developed a model that enables intuitive understanding and quantitative calculations using defining equations. Specifically, the model was implemented in spreadsheet software with 100 gas molecules in a virtual space of 100 lattices. The model showed that even such a simple model can define thermodynamic quantities and quantify the number of cases Win Boltzmann’s equation from the viewpoint of the arrangement of molecules in lattice space. This is a tool that can calculate and quantitatively examine all entropy from multiple entropy-defining equations. This calculation sheet shows that the calculated values of entropy by the Sackur–Tetrode equation and Boltzmann’s equation are almost the same. Furthermore, the entropy difference calculated using the thermodynamic defining equation dS = dQ/T was also consistent with the values by other equations. Therefore, the model can specifically calculate the values of various entropy-defining equations.

This paper shows the vibration characteristics of a sliding bearings. Especially, the self-excited vibration to be called as oil whirl generated in sliding bearing is studied in the current paper. Three methods like trajectory analysis, tracking analysis and frequency analysis of shaft vibration are analyzed to clarify the vibration characteristics of oil whirl. The oil whirl in a sliding bearing is a characteristic self-oscillation, which occurs at a rotation speed less than the twice of the critical speed of the experimental system. In addition, when oil whirl and shaft unbalance are simultaneously generated in a sliding bearing, the frequency response in all domains of frequency is suddenly become larger compared to that in the case of the only oil whirl. It seems that simultaneous development of oil whirl and shaft unbalance generate the large damage to the rotary machinery system. Furthermore, the amount of whirling to the shaft generated by the oil whirl are identified large in the horizontal, vertical and axial directions of sliding bearing. Particularly, the amount of whirling in the horizontal direction is identified larger, because, there is no suppression as gravity and structural barrier in this direction like that in the vertical and in the axial directions.

In order to research useful organic nitrogen, survival and growth of Neopyropia yezoensis protoplasts were examined using L-arginine (Arg), L-glutamic acid (Glu), Inosine (Ino) and taurine in 0.1, 1.0 and 10 mM. For survival rates for 1 week in culture, there were no significant differences except Glu in 1.0 and 10 mM. For growth for 3 weeks in culture, Arg in 10 mM was grown over two-times higher compared with control. On the other hand, growth in Glu and taurine were suppressed under every condition. Moreover, growth in Ino in 10 mM was suppressed. Our data suggested that Neopyropia yezoensis use directly organic nitrogen and has a potential to induce growth using organic nitrogen.

In order to identify effective amino acid species, survival and growth of Neopyropia yezoensis protoplasts cultured using 18 amino acids were examined. Survival rates of each protoplast cultured for 1 week with arginine, asparagine, ornithine and tyrosine were similar to that of the control condition. Other amino acids significantly reduced the survival rates than the control. Growth of each protoplast cultured for 2 weeks with β-alanine, arginine, glutamine, histidine, lysine, ornithine and phenylalanine were significantly higher than that of the control. Histidine might be useful to make only thallus grow, although survival rate was very low. Arginine and ornithine had potentials to be able to promote the growth without negative influences on the survivals of nori cells.

To clarify the effects of intertidal groundwater discharge on macrofaunal community structures of tidal flats, the species richness, abundance and biomass of macrobenthos at the groundwater-seepage area were assessed quantitatively, measuring environmental conditions including sediment temperature, median diameter, ORP and ignition loss, and salinity, water temperature and nutrient concentration of pore water at four sites (Nakatsu River mouth, Sanbyakuken, Higashihama, Oshinden) on the Nakatsu tidal flat, Oita prefecture, Japan, at low tides in June and July, 2019. A total of 1,233 individuals, belonging to 51 macrobenthic species (37 families) were collected. Mean species richness and biomass were significantly greatest at Higashihama, whereas mean abundance was greatest at the Nakatsu River mouth. Lower species richness, abundance and biomass were recorded at Sanbyakuken. At Higashihama, infaunal species such as the bivalve Glauconome angulata and polychaete Ceratonereis erythraeensis were dominant in the lower salinity and higher nutrient environments. A canonical correspondence analysis showed a positive correlation between nutrients and dominant bivalve abundance. The overall results suggested that intertidal groundwater influences the macrofaunal community structure, providing low salinity and nutrient-rich conditions, which contribute to the high productivity and diversity of marine organisms on tidal flats.

The Japanese lates, Lates japonicus is an endemic fish to the Pacific coast of southern Japan, and commonly found in estuaries and coastal waters of Miyazaki and Kochi Prefectures. The larvae, juveniles and young fish stay in the eelgrass, Zostera japonica beds in brackish water areas. Effects of water temperature and salinity on feeding and growth of immature L. japonicus were studied using combinations of seven levels of temperatures (16 to 28℃) and 6 different salinities (9 to 34 ppt) over two experimental periods each of 30 days. At each of these conditions, ten fish were reared in aquaria for periods of 30 days. Based on values of the daily feeding rates, specific growth rates and feeding efficiencies, we found that immature L. japonicus were euryhaline and at salinities ranged from 9 to 34 ppt showed similar feeding and growth rates. The suitable water temperature range was 22 to 28℃, and the optimal water temperature range was 26 to 28℃ for feeding and growth for immature L. japonicus.

The vertical migration of the first stage of five diadromous atyids (Caridina multidentata, C. typus, C. leucosticta, C. serratirostris, Paratya compressa) and two diadromous palaemonids (Macrobrachium japonicum, M. formosense) and a non-diadromous palaemonid shrimp (M. nipponense) and second zoeae of C. multidentata and M. formosense were observed under different light and salinity conditions. The first and second zoeae spread over the whole of the water column during darkness, and sank to the bottom under the light independent of the various salinity and light conditions, though there were slight differences among species. The swimming ability of the zoea is limited, thus this vertical migration is considered to be not useful for homing migration. This vertical migration at night is considered to be useful in order to feed on organic material and avoiding predators on the bottom.