Sensitivity of gametes, fertilization, and embryo development of the Japanese pearl oyster, Pinctada fucata martensii, to the harmful dinoflagellate, Heterocapsa circularisquama

Blooms of the toxic dinoflagellate Heterocapsa circularisquama cause massive bivalve kills in Japan. Mariculture of the Japanese pearl oyster, Pinctada fucata martensii, is the industry most affected by these blooms, especially in Ago Bay, Mie Prefecture, where they are frequent, cause mass mortality of oysters, and overlap with their spawning season. The goal of this August 2009 study was to assess the effects of a toxic strain of H. circularisquama isolated from Ago Bay on gametes, fertilization, and embryo development of pearl oysters. Spermatozoa, eggs, spermatozoa and eggs, and fertilized eggs of pearl oysters from Ago Bay were exposed to H. circularisquama at cell densities reported during the bloom (10–10⁴ cells mL^?1) for different periods of time. The concentration of H. circularisquama, exposure duration, and their interactions all had significant effects on gamete quality, fertilization, and embryo development. The motility and swimming velocity of spermatozoa, egg viability, fertilization, and embryo development rate were significantly reduced in all concentrations, with a cell density of 10 cells mL^?1 determined to be the critical density of H. circularisquama for deleterious effects. This is the first evidence of inimical effects of an HAB species on bivalve spermatozoa upon direct exposure. Further field and laboratory studies are required to investigate the potential effects of H. circularisquama blooms on the reproduction and recruitment of Japanese pearl oysters and other bivalves.     

Relationship between the growth and survival of larval Pacific bluefin tuna, Thunnus orientalis

We tested the hypothesis that a large body size and rapid growth rate affect the survival of larval Pacific bluefin tuna, Thunnus orientalis (PBT), and analyzed larval growth in relation to environmental conditions. Seven high density larval patches of PBT were tracked with reference buoys in the northwestern Pacific Ocean for 28–171 h in May–June from 2004 to 2008. The otolith radii and daily growth rates of the survivor larvae (collected on later tracking days of each tracking session) tended to be larger and more rapid, respectively, than those of original larvae (collected on earlier tracking days). A large body size was found to positively affect the survival of larval PBT, as did a rapid growth rate, even at an early larval stage (7 days after hatching). Generalized linear modeling showed that the otolith radius was influenced positively by the sea temperature, stratification parameter and food density, while the growth rate was influenced positively by the sea temperature and food density.     

Sediment tolerance of Sargassum algae inhabiting sediment-covered rocky reefs

Although sediment deposition has detrimental effects on macroalgal settlement and recruitment, fucoid algae (mainly Sargassum duplicatum) thrive on rocky reefs always overlaid with fine sediments in sheltered sites of Kagoshima, Japan. The aim of the present study was to assess their ability to settle and recruit onto sediment-covered substrata. A transplant experiment using boulders with Sargassum juveniles attached showed that the 30-day survival rate was as high as 50% even for the juvenile stage (<10 mm) on boulders completely buried with sediment. In addition, an outdoor tank experiment testing the effects of different sediment thicknesses (0–4 mm) on already settled 4-day old S. duplicatum germlings indicated significant reductions in growth by the presence of sediment cover even at 0.5 mm but no significant increase in mortality up to 2 mm. Furthermore, an in situ experiment in which sterilized cobbles were placed at a sediment-covered site to allow sediment to settle over them before the embryo release showed a uniformly high recruitment of Sargassum over the cobbles. This suggests the presence of unknown mechanisms to allow the settlement of propagules on substrata thinly but completely covered by fine sediments.     

Consideration on safety for emerging technology – Case studies of seven service robots

Despite the fact that several manufacturers of service robots launched their innovations into the market, worldwide guidelines or regulations concerning the safety aspects of service robots are not yet available. However the general principles and methodologies of safety of machinery (e.g., ISO/IEC Guide 51, partly ISO14121, ISO12100) could be implemented to a certain degree. The safety of seven service robots as an emerging technology was verified by safety professionals of “NPO – the Safety Engineering Laboratory” a Non Profit Organization. NPO verified the “Critical Hazards” for each service robot mentioned by the respective manufacturers. For those cases, both the “As Low As Reasonably Practicable” principle and the “Reasonable Alternative Design” standard were applied for judging if the risk associated with the Critical Hazards were tolerable or not and if state of the art measures for reducing the risk were applied adequately. These experiences will help to establish guidelines for the safety of service robots as an emerging technology in the future.     

Hydrocarbon and elemental carbon signatures in a tropical wetland: biogeochemical evidence of forest fire and vegetation changes

Evidence of changing vegetation in the tropical wetland (Rawa Danau, west Java, Indonesia) over the past 7428 years is illustrated by elemental (soot) carbon (EC) and n-alkane composition of sedimentary geolipids. In this study, vegetation changes and relevant controlling factors (e.g. forest fire and climate change) were documented on a decadal to centennial scale. The n-alkane composition that changes with depth might record changes in sources of organic matter (OM) in the wetland. The presence of EC (0.01–0.24% of organic carbon: OC) during late (0–1700 cal. year BP) and mid (3500–4500 cal. year BP) Holocene (at depths 0–50 cm, and 160–210 cm) indicated that large-scale forest fires severely affected the tropical vegetation. The hydrocarbon indices (CPI: carbon preference index, MCN: mean carbon number, and HVI: hydrocarbon vegetation index) significantly correlated with one another while a comparison of EC profile with the profiles of hydrocarbon indices indicated that n-alkane composition of the geolipid in lake sediment could record signatures of changes in catchment vegetation. Forest fire and vegetation changes might be related to regional climatic shifts relating to ENSO activity as well as being influenced by human influences.     

Metabolism of potassium bromate in rats I. In vivo studies

Potassium Bromate was administered orally to rats and its fate in the body was studied. The bromate was rapidly absorbed from the digestive tract and was partly excreted in the urine within two hours of administration. No bromate was detected in body organs or in the blood 24 hours after dosing. Excretion of bromate into the urine was proportional to the dose, except that at 2.5mg/kg or less no excretion was observed. The administration of bromate increased the bromide concentration in various organs and in urine.     

The effect of copper speciation on the formation of chlorinated aromatics on real municipal solid waste incinerator fly ash

A limited amount of information exists regarding the relationship between the chemical form of copper and the formation of chlorinated aromatics in fly ash. To understand the effects of the various forms of copper on the formation of chlorinated aromatics in real fly ash, we determined the chemical forms of copper present in various types of real fly ash using X-ray absorption near edge structure (XANES) and evaluated the relationship between the chemical forms of copper and the formation of chlorinated aromatics. Copper chloride hydroxide (CuCl2 x 3Cu(OH)2) and cuprous chloride (CuCl) were the predominant copper species found in real fly ash. Although pure cupric chloride (CuCl2) is known to be the most active catalyst for the formation of chlorinated aromatics under experimental conditions with synthetic fly ash, CuCl2 was not found in every real fly ash sample. The amount of copper chloride hydroxide was positively correlated with the formation of chlorinated aromatics in real fly ash and is, consequently, considered to be one of the key species involved in the formation of chlorinated aromatics.