Occurrence and diversity of barnacles on international ships visiting Osaka Bay, Japan, and the risk of their introduction

The occurrence and diversity of barnacles attached to the hulls of two intercontinental bulk carriers were studied at the port in Osaka Bay, Japan, to assess the potential risk of introduction of exotic species to the inner part of the bay. Barnacles were sampled from the bulbous bows, near the midship draft marks, and around the propeller posts and rudders. Twenty-two species were found, with 14 of these not previously recorded in Osaka Bay, including four species not previously recorded elsewhere in Japan. From an assessment of environmental similarity between Osaka Bay and native ranges, of the 14 species, Elminius modestus and Amphibalanus variegatus were considered to have the highest risk of introduction to the inner part of the bay.     

Development of modern benthic ecosystems in eutrophic coastal oceans: The foraminiferal record over the last 200 years,Osaka Bay,Japan

The ecosystem dynamics of a modern benthic community in Osaka Bay was studied by analyzing sediment cores and fossil foraminifera deposited during the past 200 years. The results suggest that the high-density/low-diversity assemblage has appeared in the early 1900s, coinciding with the eutrophication of the bay resulting from the Japanese industrial revolution. This assemblage proliferated during the period 1960 to 1970 when the eutrophication and bottom-water hypoxia were most pronounced. The development of the assemblage has been characterized by an increase in the relative and absolute abundance of eutrophication-tolerant species (Ammonia beccarii, Eggerella advena, and Trochammina hadai) and a decrease in many other foraminiferal species, such as Ammonia tepida, Elphidium, Miliolinella subrotunda, and Valvulineria hamanakoensis, that are unable to tolerate low-oxygen conditions. Approximately thirty years after the imposition of discharge restrictions in the 1970s, this assemblage continues to predominate in the inner part of the bay, and E. advena is currently found across the entire bay. These records make a significant contribution to understanding the long-term relationship between anthropogenic impact and ecosystem change.     

Pelagic larvae of bivalve mollusks of Amursky Bay,Sea of Japan

Larvae of 63 Bivalvia taxa were found in Amursky Bay. Of these, 47 were identified to the species level. Larvae of 55 taxa were found throughout the bay. The highest species diversity was recorded in the northeastern part and in the center of the southern part of the bay, as well as at the exit from it. Larvae of Mactra chinensis, Mytilus coruscus, Crassostrea gigas, Teredo navalis, Mya japonica, and Mysella ventricosa were widely distributed in the bay. The maximum numbers of species were observed in July and September. A comparison of species lists using the set-theory method showed that the species complexes typical of different parts of Amursky Bay are formed under the influence of the Razdolnaya River runoff flow from the north and marine waters coming from the south. The mean density of larvae during the observation period was 1100 specimens/m³ in the northern and 735 specimens/m³ in the southern part of the bay. The highest density of larvae in Amursky Bay was observed at the end of June, the beginning of July, and in September; the minimal larval density occurred in April, May, and August. While the species diversity was similarly high, the density of larvae was significantly higher in Amursky Bay than in the nearby Ussuriisky Bay.     

Brown algae (Phaeophyta) from Bahía de los Angeles,Gulf of California,México

Seven sites in Bahía de los Angeles, northern Gulf of California, were sampled seasonally over a three-year period. Five species of brown algae previously not recorded from this bay were identified: Ralfsia pacifica, Sporochnus balleanus, Hydroclathrus clathratus, Colpomenia sinuosa and Padina mexicana. Of these, H. clathratus also provided a new record for the northern Gulf of California. One species previously recorded from the bay, Dictyopteris undulata, was not observed. On a seasonal basis, temperature and biodiversity showed an inverse relationship: highest species numbers occurred in spring, when temperatures were lowest, and lowest species numbers occurred in autumn when temperatures were highest. Most species of brown algae in Baífa de los Angeles are annuals.     

Fish of Admiralty Bay (King George Island,South Shetland Islands,Antarctica)

Summary The species composition of the ichthyofauna of Admiralty Bay, King George Island was determined from results of sampling using bottom trawls, gill-nets and long-lines. Thirty-five species from 24 genera and 10 families (Table 1) were found. The number of species increased with depth (e.g. 7 species at 100 m, 14 species at 255 m and 21 species at 540 m), a tendency characteristic of Antarctic waters. In the bay, the catch rate obtained with a bottom trawl (greater than 30 kg/h) was roughly ten times lower than the catch rate using the same gear on the shelf around the Island. Notothenia gibberifrons was the dominant species in all trawls. The majority of these fish (about 95%) were immature juveniles (Table 4). Younger fish were found to inhabit shallower waters (Fig. 1). The majority of the fish of species Notothenia coriiceps neglecta, Notothenia rossii marmorata, Notothenia nudifrons, Trematomus newnesi and Trematomus bernacchii preferred waters about 255 m deep. Fourteen specimens of a previously undescribed species of the genus Psilodraco (currently being described by H. DeWitt) were caught in the bay within the 146 to 540 m depth range. The rare zoarcid, Lycenchelys aratrirostris, was also caught in Admirality Bay; previously this species had only been reported from the Elephant Island region. In the case of Trematomus newnesi, the occurrence of scales in the interorbital space was noted (Fig. 2), an observation which verifies this feature as a distinct taxonomical criterion for this species.     

钦州湾秋季和春季浮游动物分布特征及影响因素

为了解钦州湾浮游动物群落的时空分布特征及与主要环境因子的关系,于2014年10月和2015年3月进行了秋季和春季两航次的调查。结果表明:该海湾的浮游动物群落有明显的季节变化。秋季共鉴定出12类87种,其中优势种有太平洋纺锤水蚤(Acartia pacifica)、肥胖三角溞(Evadne tergestina)、亨生莹虾(Lucifer hanseni)、百陶箭虫(Sagitta bedoti)和长尾类幼虫(Macrura larvae);春季共鉴定出11类48种,优势种为中华哲水蚤(Calanus sinicus)和太平洋纺锤水蚤;秋季浮游动物的平均丰度、生物量和多样性指数(528.92个/m~3、110.60 mg/m~3和2.22)均高于春季(48.30个/m~3、61.10 mg/m~3和1.70)。空间分布上,钦州湾外湾浮游动物丰度、生物量和多样性指数的平均值皆高于内湾。多维尺度分析表明,秋季内湾群落相似性较高,春季外湾浮游动物群落相似性较高。相关性分析表明盐度与营养盐是影响钦州湾浮游动物分布的主要环境因子。与2011—2012年数据相比,钦州湾浮游动物群落结构已趋于单一化和小型化,以致生物量明显下降。这一现象主要与钦州湾海水富营养化以及大面积高密度牡蛎养殖有密切的关系。     

Distribution of Japanese temperate bass, <Emphasis Type="Italic">Lateolabrax japonicus</Emphasis>, eggs and pelagic larvae in Ariake Bay

We collected eggs and larvae of the Japanese temperate bass, Lateolabrax japonicus, and present horizontal and temporal changes of distribution relative to development and growth during the species pelagic life history in Ariake Bay. Sampling was conducted from the inner to central region (11 sampling stations) of Ariake Bay using a plankton net (80 cm diameter, 0.5-mm mesh) from November 2000 to February 2001. Both eggs and larvae were collected most abundantly in mid-December. The CPUE of eggs in the surface layer was higher than the middle layer, which is in contrast to that at the larval stage. Most eggs were collected around the central and western regions of the bay. The distribution of eggs shifted vertically to the middle layer with development. Yolk-sac larvae were collected in the central region of the bay, and preflexion and flexion larvae were more abundantly collected in the inner region of the bay. The body length of larvae around the inner bay was larger than in the central region. The pelagic life history can be summarized as follows: eggs are distributed around the central region of the bay and eggs and larvae expand their distribution to the inner and shallower waters with growth. We conclude that the shift of vertical distribution in pelagic stages and the hydrographic features of the middle layer form one of the mechanisms enabling the inshore migration of L. japonicus.     

Spatiotemporal occurrence and feeding habits of tonguefish,Cynoglossus lighti Norman, 1925, larvae in Ariake Bay,Japan

Spatiotemporal occurrence and feeding habits of tonguefish (Cynoglossus lighti Norman, 1925) larvae were investigated in an offshore area (>5 m in depth) of the inner part of Ariake Bay, Japan. All specimens were symmetric, free‐swimming larvae. Although their seasonal abundance and distribution in the study site varied from year to year, spawning started in June and the larval abundance was high in August and September with a wide distribution in the inner part of the bay. Both present and previous study results strongly suggest that larvae may settle primarily in the estuary and near‐shore areas of Ariake Bay after their wide distribution in the offshore area of the bay during the free‐swimming stage. Larvae showed a clear feeding rhythm in which they fed on prey mainly during the daytime. Larvae fed exclusively on copepods, and identified prey were mostly Paracalanidae (mainly Parvocalanus crassirostris), Microsetella norvegica, and Oithona davisae. Pre‐metamorphosis larvae fed primarily on Paracalanidae and O. davisae, whereas O. davisae formed a smaller proportion of the early‐metamorphosis diet. In early metamorphoses, larvae fed preferentially on Paracalanidae and M. norvegica.     

Annotated checklist of species of the family pomacanthidae (Actinopterygii,Perciformes) from the Nha Trang Bay (South China Sea,Central Vietnam)

Angelfishes (Fam. Pomacanthidae) of the Nha Trang Bay (Central Vietnam) are reviewed. Fourteen species of pomacanthids belonging to six genera (Apolemichthys, Centropyge, Chaetodontoplus, Genicanthus, Pomacanthus, and Pygoplites) are recorded in the bay. All species are identified on preserved material. Two new species for the bay are found: Centropyge bispinosa and C. heraldi. C. herald is new species for coastal waters of Continental Vietnam and of adjacent areas. For all pomacanthid species of the bay, areas are described, brief diagnostic characteristics are supplied, and distribution by biotopes and depths is indicated based on data of underwater observations.     

The Influence of Environmental Variables on the Distribution and Abundance of Three Elasmobranchs in Tomales Bay, California

We tested the hypothesis that temperature, salinity, and dissolved oxygen affect elasmobranch distribution and abundance in Tomales Bay, California, with monthly longline samples over a 20 month period. We used a Poisson regression under generalized least squares and found that temperature and salinity were the most important factors determining the distribution and abundance of the three most common elasmobranch species, bat ray, Myliobatis californica, leopard shark, Triakis semifasciata, and brown smoothhound shark, Mustelis henlei. Females of all three species were more abundant than males throughout the Bay, and were most abundant in the warmer, more saline inner bay. All three species apparently left Tomales Bay in late fall as water temperatures in the bay decreased to <10–12° C, and returned in early spring after temperatures increased to > 10° C. Three of 257 bat rays tagged in Tomales Bay were recaptured, all within 1km of their tagging location despite having been free for up to 583d.     

Occurrence and abundance of bregmacerotid larvae in Kagoshima Bay,southern Japan,with descriptions of ontogenetic larval characters

Regular collections of ichthyoplankton were made with a larva net at 9–14 stations from Oct. 1983 to Dec. 1988 in Kagoshima Bay, totalling 817 collections from 66 cruises. A total of 2172 bregmacerotid larvae obtained from 195 collections of 33 cruises were identified asB. atlanticus (2001),B. neonectabanus (169),B. macclellandii (1) andB. nectabanus (1, tentative identification). The peaks of mean densities of larvae collected occurred in autumn forB. atlanticus andB. neonectabanus. The larvae ofB. atlanticus occurred throughout the bay, and their densities and frequency of occurrence were lower in the northern part of the bay. In the southern part of the bay, stations in its southwest quadrant showed higher densities than the others. The larvae ofB. neonectabanus occurred only in the southern part of the bay in which stations in the northwest quadrant showed higher densities than the others.     

Materials forPythium flora of Japan. X. Occurrence,identification and seasonality ofPythium spp. in three pond waters and mud soils in Osaka

Seasonal fluctuations ofPythium species in three pond waters and mud soils in Sakai, Osaka, were studied for periods of two years and 14 months, respectively. Thirteen species and four groups were isolated from the pond waters while nine species and three groups were obtained from the mud soils. The highest frequency and total number of species were recorded in the cold and moderately warm seasons and the lowest in summer. Most of the species isolated from the pond waters have been previously recorded from aquatic habitats.     

Organochlorine Pesticides in Fishes and Mollusks from Lower Reaches of the Tumen River and of the Contiguous Part of Peter the Great Bay (Sea of Japan)

The content of persistent organochlorine pesticides (DDT and its metabolites, -, - and -isomers of hexachlorocyclohexane, HCH) were studied in the tissues and organs of some fish and molluskan species from the lower reaches of the Tumen River and the contiguous part of Peter the Great Bay (Sivuchya Bay and Zapadnaya Bay of the Furugelm Isl.) and Amursky bay. The highest total content of HCHs (785.60 ng/g of gross mass) was revealed in the digestive gland of the Japanese scallop Mizuhopecten yessoensis from Zapadnaya Bay and in the brain and the liver of the starry flounder Platichthys stellatus from the Tumen River (390.80 and 340.29 ng/g of gross mass). The maximum total content of DDT (270.70 ng/g of gross mass) was recorded in the brain of the dark plaice Pleuronectes obscurus from Zapadnaya Bay and in the liver of the far eastern smooth flounder Pleuronectes pinnifasciatus, caught in Amursky Bay to the west of Skrebtsov Isl. (212.80 ng/g of gross mass). The level of HCHs and DDT in mollusks and flounders from Zapadnaya Bay was higher than that in the same species from Sivuchya Bay. The concentration of organochlorine pesticides (OCP) in P. pinnifasciatus from the inner part of Amursky Bay at Skrebtsov Isl. was higher than in individuals of that species from the open part of the Bay at Peschany Pen. The DDT/DDE and DDT/DDT ratios evidenced the recent entry of DDT into the ecosystem of Peter the Great Bay. The southwest part of Peter the Great Bay, from the mouth of the Tumen River up to Furugelm Isl, was contaminated by HCHs to a greater extent than Amursky Bay. OCPs accumulated in appreciable quantities in the organs of fishes and mollusks of Peter the Great Bay, though their present content does not exceed sanitary–hygienic standards, a subsequent monitoring of their concentrations in biota is necessary.     

Replacement of large copepods by small ones with eutrophication of embayments: cause and consequence

Species and size compositions of the planktonic copepod community were compared between two eutrophic embayments, Tokyo Bay and Osaka Bay. Within these bays, the median body weight of the community was lowest at the innermost station and increased gradually offshore. In Tokyo Bay, which is more eutrophic than Osaka Bay, the dominant species was Oithona davisae and the median carbon weight of the community was ca 0.1 µg. In Osaka Bay, Paracalanus sp., Calanus sinicus and Corycaeus spp. were dominant and the median weight was 1–2 order of magnitude higher (2–78 µg) than in Tokyo Bay. Some 40 years ago, when eutrophication was less prominent, Acartia omorii, Paracalanus sp. and Microsetella norvegica comprised a considerable portion of the community in Tokyo Bay. The proliferation of O. davisae might have been caused with the recent change in food particle composition and/or dissociated life cycle of this species from the benthic anoxic layer. Decrease in the size composition of the copepod community may make the embayment ecosystem unfavorable for planktivorous fish, but not for jellyfish, e.g. Aurelia and Bolinopsis. This may also result in an acceleration of the flux of biogenic materials from the embayment to the outer ocean.     

Horizontal dinoflage11ate cyst distribution, sediment characteristics and benthic flux in Manila Bay, Philippines

The lateral variation of sediment properties and associated cyst content of sediment in Manila Bay were determined and their possible role/s in the occurrences of Pyrodinium bahamense Plate var. compressum (Bohm) Steidinger, Tester et Taylor toxic blooms were assessed. Manila Bay's surface sediment was determined to be silt dominated. Clay generally increased towards the coast, probably as a result of flocculation and rapid deposition upon entry of sediments from the rivers. High sand content characterized the southeastern part of the bay attributed to the greater sand inputs and relatively strong currents in this area. Bulk densities were lower in the eastern side of the bay from dilution by high organic load from sewage and urban areas. Benthic flux calculations, particularly NH3, suggest more than 50% nutrient contribution comes from sediments. In general, dinoflagellate cyst density increased from the center of the bay towards the coast, except in Pampanga Bay where it deceased near the coasts. A maximum of 23 dinoflagellate species were identified: 5 were autotrophic (Lingulodinium polyedrum (Stein) Dodge, Gonyaulax spp., Pyrophacus steinii (Schiller) Wall et Dale, Protoceratium reticulatum (Claparede et Lachmann) Butschli, and Pyrodinium bahamense var. compressum), and the rest were predominantly composed of Protoperidinium spp. and Diplopsalis spp. Heterotrophs comprised about 70% of the total cyst counts. Pyrodinium counts increased towards the northwestern part of the bay where it was the dominant autotroph species. Negative correlations were observed for live Pyrodinium cyst density and N flux, P flux, ratio of N to P and total organic carbon (TOC) content. However, areas with high N:P ratio contain abundant Pyrodinium live cysts.     

Phytoplankton and zooplankton as indicators of water quality in Discovery Bay,Jamaica

Several investigations exist which use planktonic communities as indicators of water quality in Jamaican and Caribbean Bays, however, few are conducted before there are obvious effects of eutrophication. Therefore, most of our ‘baseline’ data are for bays already severely affected by pollution. This study was conducted to assess water quality in Discovery Bay, Jamaica, before there were severe signs of eutrophication. The bay was monitored over a 12-month period (October 1995–September 1996) using 10 stations. Physicochemical data indicated a well mixed upper 5 m of water column, below which discontinuities in temperature/salinity profiles indicated the influence of colder, more saline waters associated with deep offshore currents. Physicochemical variables were within the range for oligotrophic systems with a tendency towards mesotrophic in localized areas close to the shoreline. Signs of anthropogenic stress were associated with the eastern, southwestern and western sections of the bay. Of the over 120 species of phytoplankton found in the waters of Discovery Bay, most were neritic/oceanic and diatoms dominated while 11 were found to be potentially harmful species. While these harmful species occurred at all stations they occurred most frequently at stations on the eastern side of the bay. About 107 zooplankton species were identified, 52 of which were copepods. The species also represented a mix of neritic and oceanic taxa and mean abundances for the area ranged from 1077 m⁻³ at the mouth of the bay to 3794 m⁻³ close to the south shore (station 6). Generally stations closest to shore had greater zooplankton abundances than centrally located bay stations and stations close to oceanic influence. Acartia tonsa and Lucifer faxoni showed greatest densities at shoreline areas of the bay while Oithona plumifera, Undinula vulgaris and Temora stylifera were important at stations closest to oceanic influences. These species were thus considered as indicators of these different areas within the bay. From physicochemical data and the planktonic assemblage, Discovery Bay cannot be considered polluted, it is still more accurately classified as generally pristine with mesotrophic zones in the eastern and southeastern sections of the bay. These data therefore provide a real baseline of conditions for similar tropical coastal embayments.     

Feeding habits and seasonal trophic guilds structuring fish community in the bay mouth region of a tropical estuarine habitat

Understanding trophic relationships of fish in estuarine ecosystem is an important element for sustainable resource management. This study examined the feeding habits of 29 dominant fish species, characterized the trophic guilds, assessed the impact of season and clarified the role of diets in structuring the fish community in the mouth region of Pattani Bay, Thailand. Samples of 5792 fishes collected monthly by gillnets from March 2019 to February 2020 were used for stomach content analyses. It was found that the number of food types and fullness index differed between fish taxa (P < 0.001). Most fishes were specialist feeders feeding on specific food components and were categorized into five trophic guilds: piscivore, shrimp-fish feeder, polychaete feeder, zooplanktivore and planktivore. Six species were piscivorous, considered as apex predators, that fed almost entirely on fishes. High diet overlaps among some species (>0.6) were recorded. Not much variation in seasonal guilds was observed: four guilds in the dry season, three in the moderate rainy season and four in the rainy season. Some species remained in the same guild the whole year round, but some fishes changed seasonally. Two fish communities from different regions of the bay were segregated based on feeding habits. The inner bay community comprised mainly copepod and plankton feeders, but there were more piscivores in the deeper bay mouth area. Results from this study help us to understand the feeding habits and trophic guilds of dominant fish species at the mouth of this tropical estuarine bay.     

Species composition,seasonal dynamics of quantities and spatial distribution of hydromedusae (Cnidaria: Hydrozoa) in Vostok bay of the Sea of Japan

Hydromedusae (Cnidaria: Hydrozoa) are one of the most common and widely spread plankton organisms. Due to their low quantities in the plankton and complicated species identification, they are poorly observed in zooplankton research works, especially in the Northwestern part of the Sea of Japan. The subjects of the present work are the seasonal dynamics of the spatial distribution and abundance of hydromedusae that inhabit Vostok bay (Peter the Great bay of the Sea of Japan), which were observed from April to November in 2002–2004. The timing of mature specimens was studied for different species. Eighteen species were found. Of these, Coryne sp., Tiaropsis multicirrata (Sars, 1835) and Neoturris breviconis (Murbach et Shearer, 1903) are the first records for Peter the Great Bay; the last two species are the first records for the Northwestern part of the Sea of Japan.