Open Ocean Originated Phosphorus and Nitrogen in the Seto Inland Sea, Japan

Yanagi, Tetsuo; Ishii, Daisuke

doi:10.1007/s10872-005-0008-4

Cited by 34 publications

(12 citation statements)

References 3 publications

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“…We also detected the effect of the dilution with precipitation for nutrients in Hiuchinada, i.e., negative c 1 . In the summer rainy season (JuneSeptember), although river runoff increases, the total artificial load of nitrogen tends to be diluted with freshwater in the eastern part of the Seto Inland Sea [42]; these phenomena have resulted from the regulation of total nitrogen load which began in 2000 in the Seto Inland Sea to prevent eutrophication [43]. We detected the existence of flux in our model system, i.e., positive d 1 in Eq.…”

Section: Discussionmentioning

confidence: 81%

Simulation of copepod biomass by a prey–predator model in Hiuchi-nada, central part of the Seto Inland Sea: does copepod biomass affect the recruitment to the shirasu (Japanese larval anchovy Engraulis japonicus) fishery?

2011

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We have modeled the prey-predator dynamics between nutrients, phytoplankton, and copepods in Hiuchinada, central part of the Seto Inland Sea. The model parameters were estimated by stepwise regression using data sampled from 2001 to 2005. We re-created the fluctuations in copepod biomass in the spring-summer of 2001-2004 by model simulation and investigated the relationship between the re-created copepod biomass and anchovy Engraulis japonicus reproductive success rate in Hiuchi-nada. The anchovy reproductive success rate was proportional to the copepod biomass during the last 10 days of May, a period that immediately preceded anchovy recruitment. This relationship indicates that a possible key factor in the regulation of anchovy population levels is the fluctuation in abundance of the copepod assemblage and that the crucial period for anchovy recruitment in Hiuchinada would be the period just before anchovy recruitment to the shirasu (body length: approx. 20-35 mm) fishery. These results provide a potential framework for forecasting the anchovy recruitment level that is based on both larval abundance and survival rate as estimated from the biomass of copepods in the pre-recruitment period of anchovy.

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Section: Discussionmentioning

confidence: 81%

Simulation of copepod biomass by a prey–predator model in Hiuchi-nada, central part of the Seto Inland Sea: does copepod biomass affect the recruitment to the shirasu (Japanese larval anchovy Engraulis japonicus) fishery?

2011

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“…On the other hand, nutrient supply from the open ocean could be significant even in inland seas as discussed by Yanagi and Ishii (2004); e.g., in the Seto Inland Sea, Japan. The nutrient budget for the shelf region of the East China Sea (ECS) was calculated using a box model by Chen and Wang (1999), who found that the nutrient supply to the shelf region from the open ocean could exceed that from Changjiang.…”

Section: Introductionmentioning

confidence: 99%

The Kuroshio exchange with the South and East China Seas

2009

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Abstract. The Kuroshio flows along the edges of the marginal East Asian seas such as the South China Sea (SCS) and East China Sea (ECS). Exchanges of materials and energy between the Kuroshio and the marginal seas partly control the environments of the marginal seas. In particular, saline water from the Kuroshio maintains certain salinity in the shelf water in the ECS. Nutrients from the subsurface of the Kuroshio may influence primary production on the shelf. We summarize how the Kuroshio comes into contact with the shelf water or marginal seas, describing phenomena related to the exchange between the Kuroshio and the ECS along with the SCS, using reports in the literature along with original data. The Kuroshio tends to intrude into the SCS through the Luzon Strait in various manners such as direct intrusion, associated with eddies and as a loop current. The Kuroshio intrusion into the shelf region of the ECS has distinct seasonal variation and the Taiwan Warm Current plays a significant role in the determination of water properties in the outer shelf associated with the Kuroshio intrusion. We then examine physical processes related to the interaction between the Kuroshio and shelf water. Interaction between the Kuroshio and the bottom topography is an important process in the control of the exchange around the shelf break. Vertical mixing and frontal eddies are also important factors that control the water exchange and formation of water masses in the outer shelf. Wind stress plays a significant role in the exchange with a rather event-like manner. To determine the source of the water masses, chemical tracers could be powerful tools and it is suggested that a significant part of the shelf water consists of Kuroshio intermediate water.

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“…Hayashi and Yanagi (2001) examined phosphorus cycling in the area using a numerical ecosystem model (a box model) consisting of euphotic and aphotic layers and pointed out that DIP (dissolved inorganic phosphorus) in the euphotic layer is mainly supplied by decomposition of DOP (dissolved organic phosphorus) and detritus. Moreover, the ratios of phosphorus and nitrogen originated from land and the open ocean in the Seto Inland Sea were estimated to be 0.28:0.72 and 0.19:0.81, respectively (Yanagi and Ishii, 2004). Moreover, the eutrophication caused by wastewater discharge and the effect of reclamation projects has been argued as an environmental issue in the area (e.g., Ueshima et al, 1999;Sanukida, 2002).…”

Section: Introductionmentioning

confidence: 99%

Rare earth element abundances in some seawaters and related river waters from the Osaka Bay area, Japan: Significance of anthropogenic Gd

Ogata

Terakado

2006

Geochem. J.

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Some major and trace elements in seawaters and related river waters from the Osaka Bay area, Japan were analyzed in order to examine rare earth element (REE) behaviors, especially the relationship between anthropogenic gadolinium (Gd) and nutrient concentrations. The local silicic rock normalized REE patterns for the seawaters show features of light REE depletion, negative Ce anomaly, and very small Eu anomaly. Moreover, some samples have obvious positive Gd anomalies due to contamination of Magnetic Resonance Imaging (MRI) contrast agents in medical use. We calculated the anthropogenic Gd concentrations by subtracting the assumed natural Gd concentration from the measured one. The anthropogenic or excess Gd concentrations of the seawater samples are well correlated with nutrient concentrations (NH 4 -N, NO 2 -N, NO 3 -N, PO 4 -P). Because both anthropogenic Gd and nutrients are abundant in sewage treatment plant (STP) effluents and much less abundant in non-contaminated river and seawaters, the observed trends can be explained by dilution of STP effluents with non-contaminated river and seawaters. It was found that the nutrient concentrations for a hypothetical STP effluent calculated by using these correlation lines are consistent with the average nutrient contents for the STP effluents in the study area. Moreover, we made a rough estimation of Gd budget in Osaka Bay. The estimated amount of the Gd MRI contrast agents consumed in the area seems to be consistent with the excess Gd concentrations of river and STP waters. The Gd observations in this study suggest that the Gd anomaly data can be used as a geochemical tracer of wastewater component in urban areas.

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Open Ocean Originated Phosphorus and Nitrogen in the Seto Inland Sea, Japan

Cited by 34 publications

References 3 publications

Simulation of copepod biomass by a prey–predator model in Hiuchi-nada, central part of the Seto Inland Sea: does copepod biomass affect the recruitment to the shirasu (Japanese larval anchovy Engraulis japonicus) fishery?

Simulation of copepod biomass by a prey–predator model in Hiuchi-nada, central part of the Seto Inland Sea: does copepod biomass affect the recruitment to the shirasu (Japanese larval anchovy Engraulis japonicus) fishery?

The Kuroshio exchange with the South and East China Seas

Rare earth element abundances in some seawaters and related river waters from the Osaka Bay area, Japan: Significance of anthropogenic Gd

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