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The trace element selenium (Se) is required for the biosynthesis of selenocysteine (Sec), the 21st amino acid in the genetic code, but its role in the ecology of harmful algal blooms (HABs) is unknown. Here, we examined the role of Se in the biology and ecology of the harmful pelagophyte, Aureococcus anophagefferens, through cell culture, genomic analyses, and ecosystem studies. This organism has the largest and the most diverse selenoproteome identified to date that consists of at least 59 selenoproteins, including known eukaryotic selenoproteins, selenoproteins previously only detected in bacteria, and novel selenoproteins. The A. anophagefferens selenoproteome was dominated by the thioredoxin fold proteins and oxidoreductase functions were assigned to the majority of detected selenoproteins. Insertion of Sec in these proteins was supported by a unique Sec insertion sequence. Se was required for the growth of A. anophagefferens as cultures grew maximally at nanomolar Se concentrations. In a coastal ecosystem, dissolved Se concentrations were elevated before and after A. anophagefferens blooms, but were reduced by >95percent during the peak of blooms to 0.05 nM. Consistent with this pattern, enrichment of seawater with selenite before and after a bloom did not affect the growth of A. anophagefferens, but enrichment during the peak of the bloom significantly increased population growth rates. These findings demonstrate that Se inventories, which can be anthropogenically enriched, can support proliferation of HABs, such as A. anophagefferens through its synthesis of a large arsenal of Se-dependent oxidoreductases that fine-tune cellular redox homeostasis.

Author(s): Sergio A. Sañudo-Wilhelmy (corresponding author) [1]; Antonio Tovar-Sanchez [1, 2]; Fei-Xue Fu [3]; Douglas G. Capone [4]; Edward J. Carpenter [5]; David A. Hutchins [3] The Redfield ratio of [...]

The study of trace metal cycling by aquatic protists is limited by current analytical techniques. Standard 'bulk' element analysis techniques that rely on physical separations to concentrate cells for analysis cannot separate cells from co-occurring detrital material or other cells of differing taxonomy or trophic function. Here we demonstrate the ability of a synchrotron-based X-ray fluorescence (SXRF) microprobe to quantify the elements Si, Mn, Fe, Ni, and Zn in individual aquatic protist cells. This technique distinguishes between different types of cells in an assemblage and between cells and other particulate matter. Under typical operating conditions, the minimum detection limits are 7.0 x [10.sup.-16] mol [micro][m.sup.-2] for Si and between 5.0 x [10.sup.-20] and 3.9 x [10.sup.-19] mol [micro][m.sup.-2] for Mn, Fe, Ni, and Zn; this sensitivity is sufficient to detect these elements in cells from even the most pristine waters as demonstrated in phytoplankton cells collected from remote areas of the Southern Ocean. Replicate analyses of single cells produced variations of

Junior- and senior-level science majors and first-year graduate students can learn by carrying out an environmental instrumental analysis case study examining the problem of lead (Pb) contamination in paint, drinking water, and soil of residential houses. Almost 12% of children living in older housing in urban areas have elevated blood Pb levels, with black children affected disproportionately, at about 22%. Classroom lectures illustrate instrumental techniques and analytical principles. Students, in groups of 2-3 in classes of 12, learn that instrumental/chemical analysis is only part of the process needed to address a question or hypothesis and they learn about report writing and oral presentation in a public forum.

Author(s): Sergio A. Sañudo-Wilhelmy (corresponding author) [1]; Adam B. Kustka [1]; Christopher J. Gobler [2]; David A. Hutchins [3]; Min Yang [1]; Kamazima Lwiza [1]; James Burns [4]; Douglas G. [...]

This study was conducted to determine the concentration of dissolved trace metals, DOC, DON and inorganic nutrients around Flanders Bay in Eastern Long Island, New York. The Marine Sciences Research Center, State University of New York, conducted the study.

Researchers from the State University of New York used a kinetic model to predict the bioaccumulation of trace metals in zebra mussels. Results matched field measurements in the Hudson and Niagara Rivers and Lakes Erie and Ontario conducted by the NOAA Mussel Watch program.

Implementation of the 1972 Clean Water Act has resulted in a 36-90% decrease in concentrations of Zn, Ni, Cd, and Cu in the surface waters of the Hudson River estuary.

Trace element concentrations in the surf zone and coastal waters off Baja California, Mexico, exhibited pronounced spatial gradients. Metal concentrations in these waters ranged from 0.034-0.26 nM for Cd, 0.022-0.59 nM for Co, 0.93-3.6 nM for Cu and 3.6-6.4 nM for Ni. Offshore gradients were shown by metal concentrations, with the highest levels found nearshore. The relatively high nearshore concentrations were attributed to upwelling as well as to benthic particle resuspension and diagenetic remobilization. On the other hand, the mixing of oceanic waters from the North Pacific Central Gyre and biological scavenging seemed to have partly caused the relatively low offshore concentrations.

Coastal surface waters in the Southern California Bight were subjected to silver concentration measurements. The character of silver in the coastal waters was demonstrated by offshore concentration gradient. Mass balance calculations were used to pinpoint the source of silver in US coastal waters and substantiated by elevated concentrations of silver relative to lead. It was found that wastewater discharges in coastal waters can be identified and traced by silver concentrations and lead/silver ratios.