Efficacy of Vegetated Buffers in Preventing Transport of Fecal Coliform Bacteria from Pasturelands

An experimental study was conducted in Tillamook, Oregon, USA, to quantify the effectiveness of edge-of-field vegetated buffers for reducing transport of fecal coliform bacteria (FCB) from agricultural fields amended with dairy cow manure. Installation of vegetated buffers on loamy soils dramatically reduced the bacterial contamination of runoff water from manure-treated pasturelands, but the size of the vegetated buffer was not an important determinant of bacterial removal efficiency. Only 10% of the runoff samples collected from treatment cells having vegetated buffers exhibited FCB concentrations >200 colony forming units (cfu)/100 mL (a common water quality standard value), and the median concentration for all cells containing vegetated buffers was only 6 cfu/100 mL. The presence of a vegetated buffer of any size, from 1 to 25 m, generally reduced the median FCB concentration in runoff by more than 99%. Results for FCB load calculations were similar. Our results suggest that where substantial FCB contamination of runoff occurs from manure-treated pasturelands, it might be disproportionately associated with specific field or management conditions, such as the presence of soils that exhibit low water infiltration and generate larger volumes of runoff or the absence of a vegetated buffer. Buffer size regulations that do not consider such differences might not be efficient or effective in reducing bacterial contamination of runoff.     

The structure of the latero-frontal cirri on the gills of certain lamellibranch molluscs and their role in suspension feeding

Photomicroscopy and scanning electron microscopy were used to determine the fine structure of the latero-frontal cirri on the gills of three species of bivalve mollusc: Mytilus edulis Linn., Barnea candida (Linn.), and Petricola pholadiformis Lam. The component cilia are seen to branch off alternately along the length of each cirrus. Each of these free, lateral lengths of the cilia are separated from the next on their side by a mean distance of 0.6 m. They extend to a mean length of 2.7 m in M. edulis, the species described in detail. It is shown that a complete straining mesh can be formed over the gill ostium during normal filtering and the aperture of this mesh correlates well with the previously recorded filtering efficiency for Mytilus.     

Adsorption of crude oil on arctic terrain

Arctic terrain was divided into three layers, moss, detritus and clay, and each layer was contacted with Norman Wells crude oil. Chromatographic analysis of the crude oil extracts of the terrain layers showed that the adsorption capacity of the terrain increased with increasing organic content. The higher molecular weight n-alkanes were adsorbed to a greater extent than lower n-alkanes on the moss and detritus layers. Of the aromatics, p-xylene was adsorbed to a greater extent than benzene on all three layers of the terrain. Retention of crude oil components on Arctic terrain in the event of an oil spill would be in accord with these findings.     

Increased energy expenditure due to increased territorial defense in male lizards after phenotypic manipulation

Fitness tradeoffs are difficult to examine because many fitness variables are correlated and vary in the same direction. Phenotypic manipulation circumvents many of these difficulties, and here we used this technique to examine mechanisms for tradeoffs between increased aggression (territorial defense) and survivorship. The behavioral phenotype of male mountain spiny lizards (Sceloporus jarrovi) was manipulated with testosterone to increase territorial defense, a sexually selected trait. We previously demonstrated that increased territorial defense results in a decrease in survival caused by a lower ratio of energy intake to energy expenditure. Here we measured energy consumption of increased territorial aggression using the doubly labeled water technique in the field and compared males with and without testosterone implants (Fig. 1). In a supplementary study we measured standard metabolic rate using captive lizards given similar testosterone implants to examine if an increase in energy expenditure was a result of only an increase in standard metabolic rate (Fig. 3). Our results indicated that a primary contribution to tradeoffs between increased territorial defense and survivorship could be made by a 31% increase in energy expenditure in the field that is not due to an increase in standard metabolic rate.     

Lysosomal responses to experimentally injected anthracene in the digestive cells of Mytilus edulis

Experimentally injected anthracene (10 to 100 g mussel^-1) has been shown to induce dose-dependent lysosomal destabilisation and release of hexosaminidase in the digestive cells of Mytilus edulis after 24 h. This destabilisation was accompanied by cytological evidence of cytolysis of the digestive cells. The destabilising effect of 100 g of injected anthracene persisted for 96 h with a return to the control condition by 168 h. These results are discussed in the context of environmental contamination by polycyclic aromatic hydrocarbons.     

Long-term storage of sediments: Implications for sediment toxicity testing

A study using open-top chambers ventilated with ambient or charcoal-filtered air in the vicinity of Lahore, Pakistan, has demonstrated a reduction of 46.7% and 34.8% in the grain yield for two cultivars of winter wheat (Triticum aestivum L.). The 6-h daily mean O(3) concentrations were 25-45 nl litre(-1) and on the basis of experience in North America and Europe, reductions in yield in the present study are substantially greater than might be predicted. The reasons for this discrepancy are discussed, together with implications for the suitability of a simple, relatively cheap, open-top chamber system for developing-country studies on the effects of air pollution on crops.