Processes influencing seasonal hypoxia in the northern California Current System.

This paper delineates the role of physical and biological processes contributing to hypoxia, dissolved oxygen (DO) < 1.4 mL/L, over the continental shelf of Washington State in the northern portion of the California Current System (CCS). In the historical record (1950-1986) during the summer upwelling season, hypoxia is more prevalent and severe off Washington than further south off northern Oregon. Recent data (2003-2005) show that hypoxia over the Washington shelf occurred at levels previously observed in the historical data. 2006 was an exception, with hypoxia covering ~5000 km(2) of the Washington continental shelf and DO concentrations below 0.5 mL/L at the inner shelf, lower than any known previous observations at that location. In the four years studied, upwelling of low DO water and changes in source water contribute to interannual variability, but cannot account for seasonal decreases below hypoxic concentrations. Deficits of DO along salinity surfaces, indicating biochemical consumption of DO, vary significantly between surveys, accounting for additional decreases of 0.5-2.5 mL/L by late summer. DO consumption is associated with denitrification, an indicator of biochemical sediment processes. Mass balances of DO and nitrate show that biochemical processes in the water column and sediments each contribute ~50% to the total consumption of DO in near-bottom water. At shorter than seasonal time scales on the inner shelf, along-shelf advection of hypoxic patches and cross-shelf advection of seasonal gradients are both shown to be important, changing DO concentrations by 1.5 mL/L or more over five days.

Complications following oral piercing. A study among 201 young adults in Strasbourg, France.

OBJECTIVE: This study was designed to identify and quantify the number and type of complications relating to the oral environment following piercing of tissue in the oral sphere. METHODS: The epidemiological survey included patients attending the University of Strasbourg Dental Hospital, students frequenting the University of Strasbourg canteen, and members of the public attending piercing conferences in Strasbourg, France between the months of February and June 2005. No dental examination was performed as part of this survey. RESULTS; 201 people were interviewed in this study. The average subject age was 22.7 years and 73.6% were smokers. Women comprised 72.6% of the sample population. Post-piercing complications occurred in 23.4%, but frequency depended on piercing location in relation to the oral sphere. Gingival recession occurred in 8.5%, and chipped teeth in 6.9% of the group who were aware of complications. Titanium, stainless steel and Teflon were associated with recession in 52.9%, 23.5% and 9%, and chipped teeth in 35.7%, 42.9% and 14.3% of this group respectively. CONCLUSION: The occurrence of complications was high. There is a need for public education and a further study with a dental examination.

The physical oceanography of upwelling systems and the development of harmful algal blooms.

The upwelling systems of the eastern boundaries of the world's oceans are susceptible to harmful algal blooms (HABs) because they are highly productive, nutrient-rich environments, prone to high-biomass blooms. This review identifies those aspects of the physical environment important in the development of HABs in upwelling systems through description and comparison of bloom events in the Benguela, California and Iberia systems. HAB development is dictated by the influence of wind stress on the surface boundary layer through a combination of its influence on surface mixed-layer characteristics and shelf circulation patterns. The timing of HABs is controlled by windstress fluctuations and buoyancy inputs at the seasonal, event and interannual scales. Within this temporal framework, various mesoscale features that interrupt typical upwelling circulation patterns, determine the spatial distribution of HABs. The inner shelf in particular provides a mosaic of shifting habitats, some of which favour HABs. Changes in coastline configuration and orientation, and bottom topography are important in determining the distribution of HABs through their influence on water stratification and retention. A spectrum of coastline configurations, including headlands, capes, peninsulas, Rías, bays and estuaries, representing systems of increasing isolation from the open coast and consequent increasing retention times, are assessed in terms of their vulnerability to HABs.