Coastal Waters Of Japan Research Articles

Isomer-specific accumulation and toxic assessment of polychlorinated biphenyls, including coplanar congeners, in cetaceans from the North Pacific and Asian coastal waters.

To elucidate the global distribution and toxicological impacts of polychlorinated biphenyls (PCBs) on cetaceans, the present study determined the concentrations of individual PCB congeners, including toxic non-ortho (IUPAC Nos. 77, 126, 169) and mono-ortho (IUPAC Nos. 105, 118, 156) coplanar congeners, in the blubber of 10 species of adult male odontocetes collected from several locations in the North Pacific Ocean and along coastal waters of Japan, Hong Kong, the Philippines, and India during 1985-1997. Total PCB concentrations in cetaceans from temperate and cold waters were higher than those in cetaceans from tropical regions. Residue levels were found to be the highest in Fraser's dolphins collected off Kii Peninsula, Japan, and hump-backed dolphins from Hong Kong, reflecting serious marine pollution by PCBs in industrialized Asian countries. Penta- and hexa-chlorobiphenyls were the predominant PCB congeners, accounting for about 70% of the total PCBs. 2,3,7,8-Tetrachlorodibenzo-p-dioxin equivalents (TEQs) of non- and mono-ortho coplanar PCBs in the blubber of cetaceans ranged from 36 (in spinner dolphins from the Philippines) to 510 pg/g wet weight (in hump-backed dolphins from Hong Kong). Toxic evaluation of coplanar PCBs using the TEQ concept indicates an greater impact on cetaceans from mid-latitudes. Toxicity contribution of mono-ortho congener IUPAC 118 was prominent in species from high latitude oceans, such as the Bering Sea and the North Pacific, whereas non-ortho congener IUPAC 126 accounted for the highest contribution in cetaceans from lower latitude regions, such as the Philippines and India. The estimated TEQ concentrations in the blubber of some cetacean species, such as northern right whale dolphin and Pacific white-sided dolphin from the northern North Pacific, Dall's porpoise from the Japan Sea, striped dolphin off Sanriku and Fraser's dolphin off Kii Peninsula, Japan, hump-backed dolphin and finless porpoise from Hong Kong, exceeded the levels associated with immunosuppression in harbour seals.

A note on radionuclide 137Cs and 40K concentrations in Dall’s porpoises, Phocoenoides dalli, in coastal waters of Japan

Concentrations of artificial radionuclide 137Cs and natural radionuclide 4°K in Dall's porpoise, Phocoenoides dalli, from the Pacific coast of northern Japan in 1996 are presented. Concentrations of 137Cs in muscle tissue from two male Dall's porpoises were 0.153 ± 0.01 l and 0.234 ± 0.016 Bq kg-1 wetweight, and those of4°K were 104.0 ± 0.3 and 107.8 ± 0.9 Bq kg-1 wet weight, respectively. Concentration factors (CF, concentration in animal/concentration in sea water) for the two porpoises are 59 and 90 for 137Cs, respectively. These concentrations and CF values are within published ranges for marine fish in coastal waters. The CFs obtained in this study suggest that the trophic position of Dall's porpoises is similar to that of the large piscivorous fish in the marine community in coastal waters of Japan.

Analysis of the Population Structure of the Swimming Crab, <i>Portunus trituberculatus</i> in the Coastal Waters of Okayama Prefecture, by RFLPs in the Whole Region of Mitochondrial DNA

The swimming crab Portunus trituberculatus is widely distributed in the coastal waters of Japan. This species is of commercial importance in the coastal fisheries of Japan, yielding about 4,150 tons per year.1) Artificial propagation and stocking of this species began in 1960 und er the auspices of the Ministry of Agriculture and Fish eries. The population structure of the swimming crab has been investigated previously by allozyme analysis.2) Recent ly, analysis of restriction fragment length polymorphisms (RFLPs) of the whole regional and the D-loop region4) of mitochondria) DNA (mtDNA) were performed to clarify the genetic variability and population structure. However, intra and inter-populational variability, success and the effects of stocking on the genetic composition of native populations have not yet been addressed. In the present study, the genetic variability of the swim

The Pufferfish Gene Map.

The earliest true vertebrates are represented by fish. The largest fish class, the teleosts or bony fish, contain nearly 20,000 known species. Although this class comprises only about half of all the known vertebrate species, they are probably the least well studied at the molecular level among vertebrate phyla. Until studies of the mid-1990s on the zebrafish {Danio rerio) and the pufferfish (Fugu rubripes) (2 very different teleosts), only a handful of fish genes have been listed in databases. However, because of the evolutionary position of fish, many important aspects of molecular evolution may be addressed by their study. The genomic organization of fish is very different from that of mammals. Fish chromosomes on the whole are much smaller than those of mammals. The way in which the chromosomes are constructed has a different organization. For example, fish chromosomes do not show Giemsa banding, which has been attributed to the fact that they have a less welldefined isochore structure, that is, they do not posses guanine and cytosine-poor and guanine and cytosine-rich regions (Medrano and others 1988). They also have a higher frequency of the dinucleotide CpG (Elgar 1996), the suppression of which is associated with the 5 prime ends of genes in mammals. This article and others in this Journal issue address whether such differences in the organization of other species' genes along respective chromosomes bears any resemblance to mammalian gene orders. Pufferfish are members of the Tetraodontiformes, denoting 4 teeth. The approximately 200 to 300 species in the order are found in freshwater, brackish, and marine environments. F. rubripes (also called ToraFugu or TakiFugu) (Figure 1) are marine fish found in the temperate coastal waters of Japan. Because of their size and growth rate (potentially 60 cm long and weighing more than 2 kg), they are farmed commercially and eaten as a delicacy. Since they are known to be aggressive, however, they require a large marine tank. Because they do not mature sexually for 2 to 3 yr, they are difficult and unsuitable for breeding. F. rubripes, like many of the other 23 mem-

Natural variation of radionuclide 137Cs concentration in marine organisms with special reference to the effect of food habits and trophic level

Although a number of measurements have been made on radiocesium concentrations in aquatic organisms, no clear agreement has been reached on the factors affecting accumulation of these radionuclides. Natural variations in the concentration of the long-lived artificial radionuclide '37Cs in marine organisms and factors affecting variations in marine fishes were investigated through long-term and systematic measurements in coastal waters of Japan from 1984 to 1995. Concentrations of 13'Cs were measured in more than 30 species of crustaceans, cephalopods and teleosts considered representative of the marine biotic community. A clear positive correlation (p < 0.05) was found between mean weight and concentration of 137Cs in 276 fish samples. However, different relationships between 137Cs concentration and weight of fish were observed in different species. Within 16 studied species I3'cs concentration increased with growth for 4 species, while no specific correlation was observed in the remaining species. These different patterns depended on a change of food habits with growth. Analysis of 6066 stomach contents of fish samples together with '37Cs concentrations in the stomach contents demonstrated that 137Cs concentration increased with rising trophic level and that the biomagnification factor (13'cs in p r e d a t ~ r / ' ~ ~ C s in prey) was 2.0 (95% confidence interval 1.8 to 2.2). From the yearly change of '37Cs in 24 marine fish species, a mean effectlve environmental half-life of I3'Cs of 13 * 3 yr (range 10 to 17 yr) was calculated.

Impact of Fish Net Pen Culture on the Benthic Environment of a Cove in South Japan

Over the past three decades, fish net pen culture has been developed in the coastal waters of Japan. However, serious organic pollution of the surrounding water and sediment followed the development of this new style of fishery. This paper reports a typical example of the environmental disturbance that has occurred due to the organic pollution resulting from fish net pen culture. Since fish cultivation was initiated in 1973, oxygen depletion of the bottom water and extremely reducing conditions within the sediment have occurred during the summer. These environmental disturbances resulted in unusual dynamics of the benthic communities including defaunation in the summer and recolonization of the azoic areas from autumn to the next spring. Significant changes in the benthic fauna were observed between benthic communities before and after organic pollution of the sediment. Molluscs were originally the most dominant benthic fauna. As organic pollution of the bottom sediment progressed, the molluscs were replaced by polychaetes. Likewise, total biomass of the benthic fauna decreased markedly over the past two decades. Prior to contamination, the organic matter deposited on the sediment was decomposed by the action of bacteria, ciliates, meiofauna, and macrofauna. The addition of organic material resulting from fish culture has overwhelmed these decomposition mechanisms, and conditions have worsened as organic matter is continuously added to the sediment. Contamination of marine sediment by the net pen cultivation of fish sets up a vicious cycle: the addition of exogenous sources of organic material increases the need for a more vigorous decomposition process while actually creating conditions that limit the rate of the necessary decomposition activity. The sustainable development of fish net pen culture will require the creation of a new technology that efficiently promotes the decomposition of organic matter deposited below the pen nets.

Maintenance of the fisheries environment and efforts to increase the resources in the coastal waters of Japan

The paper describes the present status of Japan's coastal fisheries resource and the anthropogenic threats to that resource. The increasing industrialization and urbanization of the Japanese coastal fringe has created threats to the important fish and shellfish resource. Legislative mechanisms, such as quality standards, together with an increasing mariculture are used to ensure the sustainable development of the coast.

日本近海におけるブリの資源生態に関する研究‐Ｉ ブリ来遊量の長期傾向

The yearly changes in catches of the yellowtail Seriola quinqueradiata in the coastal waters of Japan are analyzed. The results obtained are as follows: 1) Long-term trends of fish catches from 1947 to 1986 show different patterns among regions. 2) From the age-composition of catch in each region, older fish were more often caught in the southern regions than in the northern regions of Japan, while the reverse was the case with younger fish. 3) The migration of adult fish into the waters of Japan has been decreasing since the mid-1960's, sharply in the northern regions and gradually in the southern regions. 4) However, the recruitment of young 0-1 year-old fish has remained nearly constant since 1970 along the coast of the Sea of Japan. These results suggest that the distributional/migrational range of adult fish has been in a process of reduction and restriction to the southern regions since the mid-1960s, due to the decrease in its stock size, and that an unexploited spawning stock exists near the East China Sea and reproduces most of the young fish migrating into the Sea of Japan.

Correlation of embryonic temperature sensitivity of sea urchins with spawning season

In the coastal waters of Japan, from the subtropical area to the subfrigid area, there are several species of sea urchin with a different biogeographic distribution. The present study investigated the temperature sensitivity, as represented by the range of temperature optima for the embryos, and the dependence of developmental velocity on temperature within that range, for each of eight species of sea urchin, Echinometra mathaei, Diadema setosum, Anthocidaris crassispina, Clypeasterjaponicus, Pseudocentrotus depressus, Hemicentrotus pulcherrimus, Strongylocentrotus nudus and Strongylocentrotus intermedius. For all of these species, the optimal temperature range was confirmed to correspond well with the range of seawater temperature during the spawning season. The distributions of these sea urchins were generally correlated with their embryonic temperature sensitivities but exceptions to this correlation were found. This departure from the correlation as well as the flexibility of embryonic temperature sensitivity are discussed.

Genetic variation and population structure of red sea bream in the coastal waters of Japan and the East China Sea.

Genotypic and allelic frequencies were examined at 24 enzymatic loci in 11 samples of red sea bream from the coastal waters of Japan and the East China Sea. Nine loci (37.5%) were poly-morphic (major allele frequency less than 0.95), i.e., Aat-2, Adh, α-Gpd-1, Est, Idh-1, Me-1, 6-Pgd, and Sdh. The average heterozygosity and number of alleles per locus were 0.113 and 1.981, respectively. Comparison of allele frequencies coupled with estimates of the genetic distance (D) and the stand-ardized genetic variance (FST), indicated that the Japanese population was genetically distinct from the East China Sea population. Most of this differentiation was due to high frequency of Estc and Me-1B alleles in the East China Sea population. Comparisons of pooled allele frequencies representing the three major areas in Japan (Japan Sea, Seto Inland Sea and Pacific Ocean) did not reveal any differences. A pairwise com-parison among samples, however, revealed that Kagoshima and Kanagawa samples were signifi-cantly different from other samples. The possible explanations for the observed differences in allele frequencies among Japanese populations are discussed.

Analysis of diving behaviour of sperm whale Physeter catodon.

Some observations of sperm whales in natural conditions were made with a sonar of 20kHz at night-time in the coastal waters of Japan in 1985 and 1987 on board a whaler. The whalesdove to a maximum of 730m, or 30-162m in respective means, during diving observations of 5-13h. The surfacing and diving Feriods of the whales were 1-32 min, or 9 min in mean, and 1-47 min, or 10 min in mean respectively. However, the diving period of medium sized bachelors was relatively short, from 3-23 min. The above periods were longer in comparison than with dives during critical conditions as when chased by commercial whalers. The whales swim at speeds of 0-6kt or 3kt in mean, and medium sized bachelors generally swim faster than large bachelors. The whales swim along an 18°C-isotherm of surface temperatner, and often along or across “Shiome.”

A method for estimating mortality coefficients of chum salmon Oncorhynchus keta from tagging experiments.

Mature chum salmon are caught by coastal and river fisheries during their spawning migra-tion. In the tagging experiments of chum salmon in coastal waters of Japan, most early recaptures occurred in coastal fisheries, and the number of recaptures in the river fisheries gradually increased later. Therefore both fishing intensities are time dependent. In this paper, we consider a method for estimating the non-fishing mortality coefficient (M, day-1) and the time dependent mortality coefficients by coastal fisheries (F, day-1) and by river fisheries (R, day-1) from the tag recoveries using a method by Hearn et al. and the well known catch equation. We also apply this method to an example of actual recapture data. In this example, M was estimated to be 0.141, F varied from 0.000 to 0.100 and R fluctuated between 0.000 and 0.545.

Specific congener profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans in blue mussel in Osaka Bay in Japan: aqueous solubilities of PCDDs and PCDFs.

The authors have monitored polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the coastal waters of Japan by using blue mussel (Mytilus edulis) as a biological indicator. The levels of both chemicals were surmised to closely relate to the number of municipal incinerators and the population densities in the cities adjoining the sampling location. The main contamination source in Osaka Bay, which is heavy polluted with PCDDs and PCDFs, was determined to be the fly ash from municipal waste incinerators based upon analytical results of blue mussel from Osaka Bay sediments, sediments from Osaka Bay, and sediments from a river, which is located near a typical urban municipal waste incinerator. However, there was a remarkable difference in congener profiles of PCDDs and PCDFs between the blue mussel and the fly ash, that is, the mussel mainly contained tetraCDDs and tetraCDFs with congener ratios of 56 {plus minus} 9.7% and 62 {plus minus} 6.0%, respectively, whereas the fly ash contained the higher chlorinated PCDDs and PCDFs as major congeners. In this study, the specific congener profiles of PCDDs and PCDFs in blue mussel were investigated from the point of view of their water solubilities.

わが国沿岸域におけるドクサバフグの出現

Five cases of occurrence of the toxic swellfish Lagocephalus lunaris (BLOCH et SCHNEIDER) have been recorded from the coastal waters of Japan: two specimens from Fukagawa Bay, Yamaguchi Pref., Japan Sea, in November 1977; one from Lake Hamana, Shizuoka Pref., on November 4, 1983; one from the coastal water of Nawa-machi, Tottori Pref., on June 28, 1984; tens from the waters 9.5 miles northwest of Ikitsuki L, Nagasaki Pref., in September 1984; one from offshore Kushikino, Kagoshima Pref., on December 4, 1985. Previously, the toxic swellfish was only known to occur in the waters to the south and west of Japan. The fish described above were young and adult fish (21-41cm TL). These records extend the range of this toxic swellfish into the coastal waters of middle Japan. More specimens were recorded from the coastal waters of the East China Sea-Japan Sea side than on the Pacific coasts. Rare cases of food poisoning have been attributed to Lagocephalus spp. in Okinawa-Mie Prefectures of the Pacific side, and Naga-saki, Shimane and Fukui Prefectures of the East China Sea-Japan Sea side. It is concluded that the swellfish Lagocephalus lunaris may be responsible for these cases of food poisoning.

Isolation and characterization of a lethal hemolysin in the sea anemone Parasicyonis actinostoloides

Four species of sea anemones in the coastal waters of Japan were surveyed for hemolysins. Powerful hemolysins were detected in Parasicyonis actinostoloides and Anthopleura japonica, whereas extracts of A. fuscoviridis showed much weaker hemolytic activity and those of Haliplanella luciae no activity. Among the animal erythrocytes tested sheep were most sensitive to the hemolysins of the three positive species. The major hemolysin (parasitoxin) in whole bodies of P. actinostoloides was isolated by ion exchange chromatography, gel filtration and chromatofocusing. In addition to hemolytic activity (119900 HU/mg) it exhibited lethal activity in mice ( ld 50 65 μg/kg, i.v.) and fish Oryzias latipes (approximate minimum lethal concentration 1.5 μg/ml). Parasitoxin was slightly basic (pI 7.9) in nature and its amino acid composition was characterized by the absence of half-cystine. The molecular weight was 19,000 by SDS-polyacrylamide gel electrophoresis or 17,000 by sedimentation equilibrium, indicating that parasitoxin has no subunit structure.

瀬戸内海富栄養化海域の底生動物群集に関する研究 Ｉ 底生動物群集に及ぼす貧酸素水塊の影響

Effects of diminished dissolved oxygen supply on the benthic communities were studied in eutrophicated Hiuchi-Nada and Harima-Nada of the Seto Inland Sea, where stratification was formed in summer, 1981. The dissolved oxygen concentration was more markedly diminished at the bottom-layer, located 0.5 meter above the soft muddy sediment, in late summer than in early summer, but not so above the other sediments. Most of the benthos, found commonly in the bays or coastal waters of Japan, were molluscs and polychaetes with Theora lubrica and Paraprionospio sp. dominating, respectively. Species composition of the benthic communities didn't indicate a striking change during the summer. On the other hand, the number of species and individuals decreased logarithmically with depletion of ambient dissolved oxygen, and also the species diversity decreased gradually. This was due to a decline in number of the small bivalve Theora lubrica, inhabiting the extreme surface sediment.

Studies on the toxicity of pulp and paper mill effluents—II. Mutagenicity of the extracts of the liver from spotted sea trout ( Nibea mitsukurii)

The liver samples of spotted sea trout ( Nibea mitsukurii) caught in three different coastal waters of Japan were extracted with diethylether and then methanol. The extracts were submitted to mutagenic assay using Bacillus subtilis and Ames strains of Salmonella typhimurium. The ether extract of the liver was found to have DNA damaging potency on B. subtilis. The extract was applied to a high-speed liquid chromatography to separate into five fractions and each was tested for the mutagenic effects. The fraction of HLC-9 showed DNA damaging and mutagenic potency on B. subtilis and S. typhimurium TA 98 respectively. Gaschromatographic-mass spectrometric examination of each fraction revealed 18 organic compounds of which 12 substances were identical with those found in the sediment samples. 9,10-Epoxystearic acid was mutagenically active among them.

Distribution of Nutrients in Coastal Waters of Japan

Distribution of Nutrients in Coastal Waters of Japan

The dissolved organic iron in seawater

Using a new method of separation and determination of dissolved organic iron in seawater using Amberlite XAD-2 resin, concentrations of dissolved organic iron were determined in coastal waters of Japan and pelagic seawaters in the western North Pacific. The contents of the total iron (particulate + dissolved) and the dissolved inorganic iron were also obtained. In coastal water the total amount of iron decreases rapidly with distance from the shore. In the open sea in the coastal region, the dissolved iron varies from 2.2 to 3.8 μg1−1; of this 80 to 90% is organic. In pelagic areas, except for small maxima near the thermocline and at 4000 m, the dissolved iron content in seawater is almost constant. The mean value is 2.9 μg1−1, of which 80 to 90% is organic. It is concluded that in contrast to the general view up to now, most of the dissolved iron in seawater is in organic forms.

Histopathological and virological investigations of papillomas in soles and gobies in coastal waters of Japan.

Histopathological and virological investigations of papillomas in soles and gobies in coastal waters of Japan.