Showing papers by "Stephen J. Klaine published in 1998"

Accumulation of Selenium by the Aquatic Biota of a Watershed Treated with Seleniferous Fertilizer

Abstract: Selenium (Se) is an essential trace element. Selenium deficiency and resul tant pathologies are a problem in many domest ic animal populations. It has been hypothesized that declines in wild animal populations, specifically in several deer herds in California, are attributable to selenium deficiency (Oliver et al. 1991). This study evaluated the bioaccumulation of selenium in aquatic systems in a deer forage range treated with a seleniferous fertil izer. The selenium supplementation program in the Little Antelope Valley was designed to test the general hypothesis that selenium deficiency may be contributing to the decline in deer populations in several areas of California. A pilot study was designed that would evaluate the accumulation and transfer of selenium in a terrestrial food web. The basic hypothesis was that selenium from an aerially applied seleniferous ferti l izer would be accumulated by the native vegetation utilized by the deer for browse, and result in elevated deer blood selenium concentrations and increased fawn survival.

Algal growth rate fluctuations observed under uniform ambient test conditions using static and semicontinuous assay techniques

Abstract: A simple, manually diluted, semicontinuous, 96-h algal growth assay technique was developed to measure changing rates of population growth following sublethal chemical exposure. Rates were estimated directly from changing cell counts in a fixed volume of cell suspension. Short-term rate fluctuations in exponential rate parameters were observed in Selenastrum capricornutum populations using this method and similar fluctuations were also documented by reanalyzing conventional static culture assay data. Replicate cultures tended to fluctuate in unison, and patterns of population increase were similar in static assays initiated on different dates. The latter suggested that nonuniform rates of S. capricornutum population increase were not due simply to environmental variation. All populations were preacclimated to test conditions, but growth lags were consistently observed for 12–24 h following inoculation. Subsequent rate fluctuations probably resulted from a high degree of cell-cycle synchronization. Treating systematic rate fluctuations as random error lowered measurement precision, especially with respect to estimates of rate changes over time. Systematic variance may be difficult to eliminate in practice, but repeated-measures regression methods can account for this effect and substantially reduce rate parameter confidence intervals. Findings are expected to apply to endpoints such as dry weight, total cell volume, chlorophyll, or DNA.

Development of a continuous-flow renewal system for sediment toxicity testing†

Abstract: Development of a flow-through system for sediment toxicity testing has been difficult in part because of problems associated with the precision, and subsequent expense, necessary to create a pump that accurately delivers small amounts of overlying water. This article describes a novel continuous flow-through apparatus designed to quantitatively and continuously deliver small amounts of overlying water to individual test chambers. This system uses a series of motor-driven pistons, similar to bicycle pumps, to accurately (∼5% variability) deliver small amounts of overlying water ( 70% of saturation), but an average daily range of 0.685 and 1.67 mg/L dissolved oxygen in continuous and intermittent renewal systems, respectively, was observed. No differences were observed in midge survival between continuous and intermittent renewal, but there was a 33% decrease in growth (dry weight) of C. riparius in test chambers subjected to intermittent renewal.