Long-Term Variations of Potential Temperature and Dissolved Oxygen of the Japan Sea Proper Water

Observed potential temperatures and concentrations of dissolved oxygen are analyzed to elucidate their variations during the period from 1958 to 1996 at Stn. P (37°43′ N, 134°43′ E) and from 1965 to 1996 at Stn. H (40°30′ N, 137°40′ E) in the Japan Sea. At Stn. P, increases of the potential temperature for the period are found below 800 m depth with the largest value of 0.16 ± 0.09°C per century at 800 m depth. At Stn. H, the potential temperature increased below 500 m depth. The increase rate has the largest value of 0.50 ± 0.18°C per century at 500 m depth and it is 0.30 ± 0.09°C per century at 800 m depth. The concentrations of dissolved oxygen increased around 800 m depth at Stn. P. At Stn. H, they increased above 800 m depth. On the other hand, they decreased below 1200 m depth at both stations. The layer of the dissolved oxygen minimum has deepened in these decades. These features appearing in the distributions of temperature and dissolved oxygen are successively simulated by a vertical one-dimensional advection-diffusion model including consumption of dissolved oxygen and termination of the deep water supply. These results suggest that the supply of the Japan Sea Proper Water into the deep layer, which is cold and rich in dissolved oxygen, has been decreasing for the last four decades. This revised version was published online in August 2006 with corrections to the Cover Date.     

The Ganges and Brahmaputra rivers in Bangladesh: basin denudation and sedimentation

Every year the Ganges and Brahmaputra rivers in Bangladesh transport 316 and 721 million tonnes of sediment, respectively. These high loads of suspended sediment reflect the very high rate of denudation in their drainage basins. The average mechanical denudation rate for the Ganges and Brahmaputra basins together is 365 mm 10³ yr⁻¹. However, the rate is higher in the Brahmaputra Basin than that in the Ganges Basin. Several factors, including mean trunk channel gradient, relief ratio, runoff, basin lithology and recurring earthquakes are responsible for these high denudation rates. Of the total suspended sediment load (i.e. 1037 million tonnes) transported by these rivers, only 525 million tonnes (c. 51% of the total load) are delivered to the coastal area of Bangladesh and the remaining 512 million tonnes are deposited within the lower basin, offsetting the subsidence. Of the deposited load, about 289 million tonnes (about 28% of the total load) are deposited on the floodplains of these rivers. The remaining 223 million tonnes (about 21% of the total load) are deposited within the river channels, resulting in aggradation of the channel bed at an average rate of about 3·9 cm yr⁻¹. Although the Brahmaputra transports a higher sediment load than the Ganges, the channel bed aggradation rate is much higher for the Ganges. This study also documents a wide range of interannual, seasonal and daily variation in suspended sediment transport and water discharge. Interannual variation in sediment deposition within the basin is also suggested. Copyright © 1999 John Wiley & Sons, Ltd.     

Disturbance of recruitment success of mantis shrimp in Tokyo Bay associated with effects of hypoxia on the early life history

We investigated effects of severe hypoxia (dissolved oxygen <1 ml l⁻¹) on recruitment of mantis shrimp Oratosquilla oratoria in Tokyo Bay. Ten-year field surveys were conducted to examine quantitative relationships in annual mean densities of larvae and juveniles, and spatial distribution of juveniles and severe hypoxia. There was no significant correlation between annual mean densities of larvae and juveniles, suggesting that mortality during larval or juvenile stages varies among years, which might have regulated abundance of young-of-the-year juveniles. Juvenile density was low in the severely hypoxic area, implying that hypoxia could affect survivals and spatial distribution of juveniles. Meanwhile, there are yearly fluctuations in juvenile density in normoxic areas of both northern and southern part of the bay. This evidence suggests that abundance of post-settled juveniles might have been determined by not only effects of hypoxia, but also other factors influencing mortality during the early life stages.     

Comparison of lipids in organs of the starfish Asterias amurensis associated with different treatments

Lipids were extracted from organs of the starfish Asterias amurensis associated with different treatments(raw-control,boiling and heating),and then analyzed for lipid content,lipid oxidation index,lipid classes and fatty acid composition.Results showed that boiling softened the hard starfish shells,thus facilitating the collection of starfish organs.As compared with raw organs,the boiled organs had lower water content and higher lipid content,possibly due to the loss of water-holding capacity caused by protein denaturation.Both boiling and heating increased the peroxide value(PV),thiobarbituric acid(TBA) value and carbon value(CV) of lipids.Despite slight increases in the content of complex lipids,associated lipid composition had no substantial variations upon boiling and heating.For simple lipids,the content of 1,2-diglyceride decreased in boiled and heated organs,with free fatty acids observed on thin layer chromatography(TLC).However,neither boiling nor heating significantly changed the fatty acid compositions of simple or complex lipids in starfish organs,suggesting that these two treatments had no significant effects on complex lipids in starfish organs.Together,our results indicated that boiling of starfish soon after capture facilitated the handling and extraction of useful complex lipids consisting of abundant glucosylceramide and eicosapentaenoic acid(EPA)-bounded phospholipids.     

Year-round accumulation of particulate organic matter in the estuarine turbidity maximum: comparative observations in three macrotidal estuaries (Chikugo, Midori, and Kuma Rivers), southwestern Japan

The inner part of the Ariake Sea is one of the most productive estuarine systems in Japan. To examine potential food items for estuarine organisms, we conducted monthly observations of the dynamics of particulate organic matter along the macrotidal Chikugo River estuary in 2005 and 2006. In the neighboring macrotidal Midori and Kuma River estuaries, comparative observations were made. High turbidity and strong vertical mixing were observed only at low salinities (<10) in the Chikugo River estuary. In contrast, the Midori and Kuma River estuaries were characterized by less turbid and less mixed waters. Concentrations of particulate organic carbon often exceeded 5?mg?l^?1 in or close to the estuarine turbidity maximum (ETM) of the Chikugo River estuary. However, such high concentrations were rarely observed in the other two estuaries. The observed differences could be attributable to different hydrodynamic processes related to the different lengths of tidal reaches: 23, 8, and 6?km in the Chikugo, Midori, and Kuma Rivers, respectively. In the Chikugo River estuary, spatiotemporal changes of chlorophyll a suggested that phytoplankton occurred abundantly up- and/or downstream from the ETM especially during the warm season. In contrast, pheophytin (i.e., plant detritus) always accumulated in or close to the ETM. Carbon stable isotope ratios and carbon to nitrogen ratios indicated that the plant detritus was derived from phytoplankton and terrestrial plants. The Chikugo River estuary has a high potential to support the production of estuarine organisms through abundant plant detritus in the well-developed ETM all the year round.     

Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services

Location-Based Services (LBS), an emerging new business based on smartphone and mobile networks, are becoming more and more popular. Most of these LBSs, however, only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role. Our specific aim is to solve these issues. This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders.     

Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services

Location-Based Services (LBS),an emerging new business based on smartphone and mobile networks,are becoming more and more popular.Most of these LBSs,however,only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role.Our specific aim is to solve these issues.This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders.     

On the gravity wave-driven instability of E layer at mid-latitude

The plasma instability process during internal gravity wave propagation through the ionospheric E region is considered. The growth rate of the instability has been found and it has been shown that it depends on perturbation wavelength, gravity wave parameters and direction of propagation. The conditions for the instability are favorable when the vorticity of the associated neutral motion becomes antiparallel to the geomagnetic field. In the proposed instability mechanism plasma irregularities could seed the large-scale sporadic E layer structuring because they are generated in situ as a part of the same neutral wind structure that serves to initiate the formation of the layer.