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Little is known about the dynamics of marine food chains spanning primary to higher trophic levels on centennial and longer timescales, especially where the supply of dissolved iron limits primary productivity. To elucidate the long-term dynamics of biological productivity in the Coastal Oyashio (CO), which is a major pathway for transporting dissolved iron into the western North Pacific from winter to spring, we reconstructed the lower trophic level productivity over the last 3000 years in the CO. Our results demonstrate that the concentrations and mass accumulation rates of both Chl-a (chlorophyll a and its derivatives) and biogenic opal used as proxies of primary productivity, and steryl chlorin esters (SCEs) used as that of zooplankton productivity, show a millennial-scale increasing trend and centennial-scale variability beginning ca. AD 400. SCEs were positively correlated with Chl-a, indicating that changes in zooplankton productivity were induced by bottom-up control of primary productivity. The Chl-a and SCEs showed synchronous centennial-scale patterns with a relative abundance of sea-ice-associated diatom species transported by CO, and with a ventilation index in the Okhotsk Sea IntermediateWater. This synchronous pattern indicates that lower trophic-level productivity during the spring bloom responded to the intensity of iron-replete CO. [ABSTRACT FROM AUTHOR]

Recently, blue carbon – carbon captured by coastal ecosystems – has been gaining increased research attention for its potential to sequester anthropogenic CO2. The Amagasaki Canal, in the inner part of Osaka Bay, Japan, has high nutrient concentrations and phytoplankton abundance; primary production by phytoplankton is high in such hypertrophic environments. This could lead to the enhanced absorption of atmospheric CO2. This study investigated the temporal changes and spatial variability in water quality and CO2 flux in the Amagasaki Canal, and it analyzed factors affecting the partial pressure of CO2 (pCO2) in canal water using covariance structure analysis. The CO2 flux in the canal varied between −24.9 and 66.8 mmol-C/m2/d. There were seasonal changes in water quality, with a tendency of CO2 release during autumn and winter. In spring and summer, when phytoplankton were active and chlorophyll-a concentrations were high, concentrations of dissolved inorganic carbon were low and atmospheric CO2 was absorbed into the water. Covariance structure analysis indicated that biological processes indirectly influenced pCO2 via pH and dissolved oxygen concentrations, pointing to the contribution of the primary production rate as part of the biological processes. [ABSTRACT FROM AUTHOR]

• The scientific knowledge on the southern Okhotsk Sea biogeochemistry and its relationship with its rich primary productivity was actualized. • The formation mechanisms of different water masses are starting to be revealed using chemical tracers, especially radionuclides. • The high seeding potential of Thalassiosira by ice–melting has been repeatedly featured, and it was placed as reason for its highest abundance in spring. • The total carbon mass flux is highest in April – June. Its maximum (up to 1165 mg C m−2 day−1) occurs several days after the sea ice retreatment • Further research is needed on the formation of the Intermediate Cold Water, the Cold Water Belt and the solubilization process of particulate Fe. The southern Okhotsk Sea is one of the best fishing grounds in Japan, and the biogeochemistry, primary productivity, and physical aspects of this region have been heavily researched. However, a comprehensive review of the literature has not been written since that by doctor Takatoshi Takizawa more than 40 years ago (1982). This review actualizes the share–ground knowledge of the influence of oceanographic conditions on the primary productivity of the area. This review includes topics from physical/chemical oceanography and hydrobiology, focusing on the complex oceanological structures that support the high primary productivity of the southern Okhotsk Sea. It is known that the formation of all water masses is ultimately a consequence of the seasonal interchange of the Soya Warm Current and the East Sakhalin Current. However, it was revealed that there may be over- or under-estimations in different material and heat fluxes among water masses, especially regarding the dense Soya Warm Current. Recent studies have investigated the formation mechanisms of different water masses using chemical tracers, particularly radionuclides. Although promising if properly combined with traditional techniques, more isotopes or compounds are required to derive further conclusions. In terms of biological aspects, the high seeding potential of Thalassiosira after sea ice melting has been featured by many authors, and it was considered as the reason for its highest abundance in spring. The total carbon mass flux, which is essential for scallop farming, is highest in April – June, normally 120 – 160 mg C m−2 day−1. The total carbon mass flux is maximum (up to 1165 mg C m−2 day−1) after the spring bloom peak, and the spring bloom is strongly linked to sea ice retreatment. It was identified that the routes of 134Cs towards the Intermediate Cold Water, the formation mechanism of the Cold Water Belt, and the solubilization process of sea ice-carried particulate Fe require further research. Three major potential threats were identified, including the appearance of alien toxic species, a decrease in sea ice production in the northern parts of the Okhotsk Sea, and offshore gas and oil drilling northeastern of the Sakhalin Island. Publicly available scientific knowledge about the biogeochemistry of the southern Okhotsk Sea and its relationship with its rich primary productivity was actualized to 2022, anticipating that this work will become the starting line for many early career scientists endeavoring in interdisciplinary studies. [ABSTRACT FROM AUTHOR]

Japan's fisheries, among the largest in the world, are currently facing overcapacity. As of 2017, approximately half of the 37 stocks with abundance estimates were either overfished or subject to overfishing. In response, in December 2018, the government of Japan enacted revisions to the Fisheries Act which was modeled partly on the systems used in the United States and the EU. Implementing these changes will take time, as lessons learned from other countries are incorporated. Over the past 26 years, the United States has undergone a similar succession of amendments to its fisheries law, yielding a system that has been largely successful in reducing overfishing and rebuilding overfished fisheries. We compare the Japanese and U.S. approaches to fisheries management in four areas that may explain the differences in the number of stocks that are overfished: 1) overall structure of fisheries management and who is responsible for conducting the management, 2) the specificity and goals of fisheries laws in each country, 3) the role and independence of science in the management process, and 4) the approach to scientific and management uncertainty. • Fishery management systems seek to balance the conservation of fishery resources with the benefits to fishing communities. • The United States' system asserted the primary importance of conserving biological productivity of fisheries in 1976. • Japan's pre-form fisheries management system prioritized the economic well-being of fishing communities. • Both systems recognize the important role of scientific advice that is not influenced by political decisions. • The U.S. has built strong protocols by which scientific information is reviewed and results are passed to the management system. [ABSTRACT FROM AUTHOR]

“Satoumi” is a Japanese term meaning a seascape where human-ecosystem interaction has resulted in increased biodiversity and productivity, thus improving the health of the environment and its ecosystem services. However, this definition does not do justice to the universality of the concept, and the holistic ideas and related valuable practices promoted by the term, applicable to fisheries science, contributing thus to the neglect of the term in the international stage. This article explores the importance of environmental, commercial, and research activities related to Satoumi, based on actions implemented by Fisheries Cooperative Associations (FCAs) of different prefectures in Japan. The examined case studies are bottom-up initiatives undertaken by Japanese fishermen and constitute effective means towards sustainable and competitive fisheries management. Such initiatives play an important role in disseminating the positive effects of the Satoumi approach in Japan, and promote therefore its adoption in other regions of the world as well. [ABSTRACT FROM AUTHOR]

Environmental conservation and management policy first emphasized on water pollution control in Japan. However, this kind of passive conservation policy is gradually being shifted to an active approach such as Satoumi, which includes the restoration of biodiversity, biological productivity, habitat and a well-balanced nutrient cycle between land and sea. Many Satoumi creation activities were also characterized by activities which promote interactions between land and sea. In this paper, a case study of Ago Bay in Shima City, Mie Prefecture, Japan, is introduced in which land-sea interaction at two sites was improved by promoting water exchange across dikes constructed for land development and land reclamation. Tidal flat restoration experiments conducted in Ago Bay clearly showed that the promotion of tidal exchange between the sea and wetland area on the inner side of dikes improved both deteriorated sediment quality and macro-benthos conditions. Along with the results of this case study, future tidal flat restoration in Japan is also discussed. [ABSTRACT FROM AUTHOR]

Environmental conservation and management policy first emphasized on water pollution control in Japan. However, this kind of passive conservation policy is gradually being shifted to an active approach such as Satoumi, which includes the restoration of biodiversity, biological productivity, habitat and a well-balanced nutrient cycle between land and sea. Many Satoumi creation activities were also characterized by activities which promote interactions between land and sea. In this paper, a case study of Ago Bay in Shima City, Mie Prefecture, Japan, is introduced in which land-sea interaction at two sites was improved by promoting water exchange across dikes constructed for land development and land reclamation. Tidal flat restoration experiments conducted in Ago Bay clearly showed that the promotion of tidal exchange between the sea and wetland area on the inner side of dikes improved both deteriorated sediment quality and macro-benthos conditions. Along with the results of this case study, future tidal flat restoration in Japan is also discussed. [ABSTRACT FROM AUTHOR]

Satoumi has long been practiced in Japan and is recently being promoted in pursuit of sustainable integrated coastal zone management (ICZM) and biodiversity conservation. Satoumi is considered as "a sea where high productivity and conservation of biological diversity are achieved through human intervention in harmony with natural ecosystems." In this study, four satoumi cases were selected, Shiretoko, Ago Bay, Hinase, and Nanao Bay, in order to assess their effectiveness in coastal management, biodiversity conservation, and socioeconomic impacts. In all four cases, positive changes in local coastal ecosystems were found, including an increase in local biodiversity, improvement in water quality, and restoration of ecosystems. There were also significant socioeconomic outcomes such as involvement of wider stakeholders, mainstreaming of biodiversity, and promotion of local products and tourism. Also, by comparing the four cases, some key characteristics of satoumi that contribute to management effectiveness were identified. These are setting clear targets, leadership by key persons, and the driving force of important stakeholders such as fishers and local businesses, who have a profound and historical stake in coastal management. • We examined 4 cases of satoumi-type coastal management sites in Japan. • All 4 cases showed positive effects on ecosystem. • 2 cases showed increase in local biodiversity as a result of ecosystem restoration. • Socioeconomic impacts of satoumi are also significant. • Key factors for successful satoumi implementation were identified. [ABSTRACT FROM AUTHOR]

We report on a 16-month time series of the primary productivity, chlorophyll biomass and environmental variables in Ishikari Bay, the western Hokkaido coast, from September 2006 to December 2007. During productive summer and autumn seasons, the average phytoplankton biomass (as chlorophyll a) and productivity were 4.7 ± 0.4 μg Chl a L−1 and 229.2 ± 113.4 μg C L−1 d−1, and 5.9 ± 6.0 μg Chl a L−1 and 138.9 ± 202.6 μg C L−1 d−1, respectively. The water column salinity profiles suggested that nutrient upwelling from bottom waters, especially in summer and autumn, when autotrophic production was at a maximum, was the major source of nutrients fueling the productivity in near-surface waters. Size-fractionation measurements showed that the micro-size fraction (>10 μm) accounted for > 80% of the total phytoplankton biomass and productivity. The strong correlation of POC with Chl a (r = 0.875; P < 0.001; n = 16) suggests that living phytoplankton in POC may outweigh detrital and bacterial biomass. Stoichiometrical analysis of inorganic nutrients revealed a seasonal low (13) and high (25) DIN-to-PO4 ratio and a seasonal low (30) and high (37) Si-to-PO4 ratio, suggesting that phytoplankton growth was possibly limited by nitrate and phosphate and not by silicic acid. We conclude that bottom-advection of nutrients resulting from wind-driven mixing may have been a significant source of nutrient input in this oligotrophic coastal system, and zooplankton grazing or other losses might be a crucial factor in controlling the phytoplankton biomass and production, particularly in spring. Also, it is probable that phytoplankton growth was not prevented by insufficient light in Ishikari Bay considering the values of both mean light intensity in the mixed layer (I m) and the mixing and euphotic depth ratio (Z mix:Z eu). [ABSTRACT FROM AUTHOR]

Horizontal, vertical and temporal distribution of a cyclonic (counterclockwise) eddy, where biological productivity is high, downstream of the Tsushima Islands in the eastern channel of the Tsushima Straits in November 2007 was revealed using conductivity-temperature-depth and acoustic Doppler current profiler data. The eddy had a horizontal scale of approximately 40-60 km, and the accompanying baroclinic current was more than 15 cm s at the edge of the eddy. The island-induced cyclonic eddy moved east-northeastward at about 10 km day (∼10 cm s) along the Tsushima Warm Current and was intensified by the barotropic instability in the current shear. The cyclonic eddy with high surface chlorophyll a concentrations intensified in the vicinity of the Tsushima Islands and was advected by the Tsushima Warm Current towards the southwestern Japan Sea. [ABSTRACT FROM AUTHOR]

Abstract: In order to understand the oceanographic changes before the Guadalupian–Lopingian (Permian) boundary mass extinction event, we investigated the isotopic compositions of the inorganic carbon and the oxygen (δ 13Ccarb and δ 18Ocarb) of the Guadalupian (Middle Permian) shallow marine carbonates deposited on a seamount-top in the superocean Panthalassa. The drilled samples were obtained at Kaerimizu in the Akiyoshi area, SW Japan. We focused on the Roadian-Wordian (Middle Guadalupian) interval that spans over 7 fusuline zones; i.e. the Parafusulina kaerimizuensis Zone (Pk Z.), Afghanella ozawai Zone (Ao Z.), Neoschwagerina craticulifera robusta Zone (Ncr Z.), Verbeekina verbeeki – Afghanella schenki Zone (Vv – As Z.), Neoschwageina fusifor m is Zone (Nf Z.), Verbeekina verbeeki Zone (Vv Z.), and Colania douvillei Zone (Cd Z.), in ascending order. Analytical results showed that the δ 13Ccarb values stayed almost constant around +3.0‰ PDB in the Pk Z., Ao Z. and the lower half of the Ncr Z., and those in the upper-section gradually decreased down to −2.0‰, of which the lowest was found in the Cd Z. We statistically extracted the samples with presumably better preserved δ 13Ccarb values in the Kaerimizu section ranged between +0.5 and +4.0‰ with average values of δ 13Ccarb of +2.7±1.0‰, on the basis of δ 13Ccarb–δ 18Ocarb characterization. This interval shows a monotonous decrease in δ 13Ccarb values from ca +4.0‰ to +2.0‰. This indicates that the primary productivity might be generally high in the Wordian mid-oceanic domain but slightly declined in the Late Wordian. The studied Early-Middle Guadalupian interval is chemostratigraphically correlated with the other mid-Pansalassan paleo-atoll limestone e.g. Iwato Formation in Japan, suggesting that the relatively high δ 13Ccarb (over +3.0‰) of seawater predominated in shallow mid-superocean during the middle Middle Permian. [Copyright &y& Elsevier]

In mountainous areas, irregular terrain significantly affects spatial variations of climatic variables and the reflectance of pixels in remote sensing imagery. Consequently, the variations may affect the estimation of net primary productivity (NPP). The light-use efficiency (LUE) model is used to analyse topographic influence on NPP by evaluating topographic effects on primary input data to the model, including both Normalized Difference Vegetation Index (NDVI) and climatic data. A typical green coniferous forest in Yoshino Mountain, Japan, was employed as the study area. The results show that the average NPP is significantly increased after removing topographic influences on NDVI; the average NPP has a relatively minimal change when only topographic effects on climatic data are considered. When both topographic effects on NDVI and climatic data are considered, the average NPP is 1.80 kg m-2 yr-1, which is very similar to the ground measurement result of 1.74 kg m-2 yr-1. [ABSTRACT FROM AUTHOR]

Recent studies have suggested that gross primary production (GPP) of terrestrial vegetation can be estimated directly with the satellite-based Enhanced Vegetation Index (EVI). However, the reported EVI–GPP relationships showed wide variability, with the regression functions showing widely scattered data. In the present study, we examined the possible reasons for this variability in the EVI–GPP relationship using daily EVI values from satellite and field measurements and daily flux-based GPP in a cool-temperate deciduous broad-leaved forest in Japan. The variability appears to be caused by noise due to cloud contamination in the satellite data as well as the different seasonality of EVI and GPP, especially during the leaf-expansion period. Our findings indicate that improvement of cloud screening and consideration of the leaf-expansion period are critical when applying the EVI–GPP relationship. [ABSTRACT FROM AUTHOR]

The effects of atmospheric nitrogen input on biological production in the Japan Sea have been investigated using a coupled physical-ecosystem model. Comparison between the cases with and without nitrogen deposition shows a relatively large effect on primary production in the southern Japan Sea during summer to autumn, when nitrogen deposition is high and nutrient is depleted in the surface layer. The atmospheric nitrogen deposition supports > 10% of the annual export production in the nearshore region along the Japanese coast. The importance of atmospheric input as a new nutrient will grow steadily with increasing deposition into the Japan Sea. [ABSTRACT FROM AUTHOR]

Microbial communities in a shallow submarine hydrothermal system near Taketomi Island, Japan, were investigated using cultivation-based and molecular techniques. The main hydrothermal activity occurred in a craterlike basin (depth, ~23 m) on the coral reef seafloor. The vent fluid (maximum temperature, >52°C) contained 175 μM H2S and gas bubbles mainly composed of CH4 (69%) and N2 (29%). A liquid serial dilution cultivation technique targeting a variety of metabolism types quantified each population in the vent fluid and in a white microbial mat located near the vent. The most abundant microorganisms cultivated from both the fluid and the mat were autotrophic sulfur oxidizers, including mesophilic Thiomicrospira spp. and thermophilic Sulfurivirga caldicuralii. Methane oxidizers were the second most abundant organisms in the fluid; one novel type I methanotroph exhibited optimum growth at 37°C, and another novel type I methanotroph exhibited optimum growth at 45°C. The number of hydrogen oxidizers cultivated only from the mat was less than the number of sulfur and methane oxidizers, although a novel mesophilic hydrogen-oxidizing member of the Epsilonproteobacteria was isolated. Various mesophilic to hyperthermophilic heterotrophs, including sulfate-reducing Desulfovibrio spp., iron-reducing Deferribacler sp., and sulfur-reducing Thermococcus spp., were also cultivated. Culture-independent 16S rRNA gene clone analysis of the vent fluid and mat revealed highly diverse archaeal communities. In the bacterial community, S. caldicuralii was identified as the predominant phylotype in the fluid (clonal frequency, 25%). Both bacterial clone libraries indicated that there were bacterial communities involved in sulfur, hydrogen, and methane oxidation and sulfate reduction. Our results indicate that there are unique microbial communities that are sustained by active chemosynthetic primary production rather than by photosynthetic production in a shallow hydrothermal system where sunlight is abundant. [ABSTRACT FROM AUTHOR]

Net and gross primary production (GPP), based on the incorporation of 13C-labeled inorganic carbon into particulate carbon and O2 production, were compared from September 2001 to July 2003 in Sagami Bay, Japan. Euphotic zone integrated GPP, 13C uptake, and their ratio (13C uptake:GPP) ranged from 40 to 331, 14 to 163 mmol C m-2 d-1, and 0.34 to 0.69, respectively. The 13C uptake:GPP ratios were relatively lower in summer (low nutrient, LN) than from fall to spring (high nutrient, HN), with a mean value (±standard error) of 0.52 ± 0.03 during the study period. The mean value of the ratio in the upper water column above which 20% of surface light penetrates was higher during HN than during LN periods. On the contrary, no significant differences were observed between HN and LN periods in the depths at which <10% light penetrates. Algal respiration was 36% of GPP in the study periods. The sum of 13C uptake and algal respiration accounted for 58-100% of GPP, with a mean value of 80%. This implies that about 20% of GPP might have been excreted as dissolved organic cargon and/or mineralized as light respiration. [ABSTRACT FROM AUTHOR]

In this study we compared two different climate datasets, one from the National Center for Atmospheric Research (NCAR) of the USA and the other one from the Japan Weather Association (JWA), by inputting the climate data to the same ecosystem model, the Boreal Ecosystem Productivity Simulator (BEPS), to examine how the data quality of the climate input affected the estimate of NPP in 1998 on Hokkaido Island, Japan. The JWA dataset was derived from a high-density weather station network with adjacent stations about 17–21 km apart and served as our high quality climate data. The original NCAR dataset (about 0.9°×0.9°) was resampled at 1 km×1 km resolution using the bilinear interpolation method and served as our “poor” quality data source. We found that, on average, the NCAR dataset underestimated the 1998 NPP by 15% over the whole study area compared with the JWA dataset, by 21% in needle forest, by 18% in grass/cereal-cropland, by 14% in broadleaf forest, by 11% in broadleaf crops, and by 2% in shrubs. However, the NCAR dataset slightly overestimated NPP by 1% in savannas in comparison with the JWA dataset.We also found that using the NCAR temperature data (daily maximum and minimum temperatures), specific humidity, and precipitation underestimated regional NPP by 17, 7, and 2%, respectively, compared with the JWA dataset. However, using the NCAR global solar radiation did not significantly change the estimate of NPP although the NCAR solar radiation was much greater than the JWA solar radiation. By using a new sensitivity analysis technique called the Extension of Fourier Amplitude Sensitivity Test (EFAST), we found that the required accuracy for the 1998 growing season was ±2.9 °C for daily maximum temperature, ±2.0 °C for daily minimum temperature, ±2.5 MJ/m2 per day for daily global solar radiation, and ±3.4 g/kg for daily specific humidity to estimate NPP with an overall confidence coefficient of 95% in the Hokkaido Island. The analytical approach developed in this study can also be applied to other input variables/parameters and other ecosystem models. [Copyright &y& Elsevier]

Combined methods of size fractionation and single-cell isolation were used to investigate the seasonal variation of phytoplankton dynamics in Tokyo Bay with an emphasis on primary productivity. Red tides occurred in Tokyo Bay from spring to autumn; a diatom, Skeletonema costatum, and a raphidophycean, Heterosigma akashiwo, were the most important primary producers. Small diatoms and flagellates, including these species, were dominant and showed rapid changes of phytoplankton community structure within several days in summer. The nanoplankton (3–20 μm) fraction contributed most to chlorophyll a concentration and primary productivity during spring to autumn, whereas the microplankton (>20 μm) contribution was remarkable in winter. Picoplankton (<3 μm phytoplankton) remained relatively constant throughout the year. A significant reverse relationship was obtained between assimilation rate and chlorophyll a content for the total and nanoplankton population; the assimilation rate was high at the initial phase of the bloom, then decreased to a minimum level at the peak of the bloom. Factors controlling the reduction of assimilation rates at the peak, and changes in phytoplankton community structure, are discussed. [ABSTRACT FROM PUBLISHER]

The characteristics of aerosol methanesulfonic acid (MSA), non-sea-salt sulfate (nss-SO 4 2−) and MSA/nss-SO 4 2− ratio, were measured at high-time resolution (1 h) over the East sea/sea of Japan (R1, 31° - 47°N, 121° - 145°E), western North Pacific Ocean (R2, 47° - 58°N, 145° - 176°E), subarctic western North Pacific (R3, 58° - 66°N, 176°E - 169°W) and Arctic Ocean (R4, 66° - 85°N, 150–174°W) during July–September 2018. The highest MSA levels were observed in R2, with an average of 0.22 ± 0.18 μg m−3. These levels were 3–10 times higher than in other regions, correlating with biological productivity. The concentration of nss-SO 4 2− decreased with distance from Eurasia. The MSA/nss-SO 4 2− ratios were 0.10 ± 0.27, 0.38 ± 0.43, 0.30 ± 0. 36 and 0.39 ± 0.48 over R1, R2, R3 and R4, respectively. Biological sources were larger contributors of nss-SO 4 2− in R2 while nss-SO 4 2− were affected more by continental anthropogenic sources in R1. Positive and negative relationships between the MSA/nss-SO 4 2− ratio and temperature were observed, indicating that temperature may have a different influence on the MSA/nss-SO 4 2− ratio. Four high level regions of MSA were observed over the R4, wind speed and temperature were critical factors that affected MSA levels over the R4. Significant depletion of chloride was observed and areas that were more affected by terrestrial sources had a greater chlorine depletion in this study, which means that the magnitude of the chlorine depletion followed the order R1 > R3 > R2 > R4. • MSA, nss-SO 4 2− and MSA/nss-SO 4 2− were measured at high-time resolution over the western North Pacific and the Arctic Ocean. • Wind speed and temperature were critical factors that affected atmospheric MSA levels over the Arctic Ocean. • Significant chloride depletion was observed in this study due to acid displacement and anthropogenic pollutants. [ABSTRACT FROM AUTHOR]

The production and metabolism of the amphipod Themisto japonica in Toyama Bay, southern Japan Sea, were estimated based on their biomass and population structure data collected from every 2-week samplings from 1 February 1990 through 30 January 1991 (363 days). Over the sampling period, the mean biomass (B) was 370 mg C m-2. Production (P) was calculated as the sum of somatic (Pg) and molt (Pe) production (P = Pg + Pc), and metabolism (M) as the sum of routine metabolism (Mrtn) and diel vertical migration (Mdvm). Integrating over the entire sampling period, Pg and Pe were 1934 and 176 mg C m-2, respectively, and Mrtn and Mdvm were 4100 and 1778 mg C m-2, respectively. Mean daily P/B and Pg/B ratios were 0.016 and 0.014, respectively, and mean Pg/M and P/M ratios were 0.33 and 0.36 respectively. Assuming assimilation efficiency of 0.904, ingestion was computed as 8837 mg C m-2 per 363 days. For the daily maintenance of growth and metabolism, the T.japonica population needs to ingest an amount of prey which equates to 6.6% of their biomass, or 30% of possible total production of their prey animals (copepods and small euphausiids) in Toyama Bay. [ABSTRACT FROM PUBLISHER]