departmental bulletin paper

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.