Contribution of the natural biota associated with substrates to the nutritional requirements of the post-larval shrimp, Penaeus esculentus (Haswell), inhigh-density rearing systems

The contribution of epiphytes associated with physical substrates to the nutritional requirements of post‐larval shrimp, Penaeus esculentus Haswell, was determined in high‐density rearing systems (3000, 6000 and 11 000 m^?3). Stable isotope signatures of epiphytes on polyethylene mesh substrate, AquaMats? and tank walls were compared with shrimp signatures. Two methods were used: the determination of carbon and nitrogen natural abundance ratios; and ¹⁵N‐nitrogen enrichment ratios after the addition of ¹⁵N‐ammonium to tanks. Using the natural abundance technique and a simple mixing model, epiphytes were found to contribute substantially to the carbon requirements of post‐larval shrimp (39–53%). This was despite the addition of formulated feed at satiation levels. There was no indication of a reduced contribution of carbon from epiphytes to shrimp nutrition at higher shrimp densities. The lack of a difference in the ¹⁵N/¹⁴N ratios of the two food sources meant that mixing models could not be used to calculate the contribution of nitrogen from epiphytes vs. artificial feed to shrimp nutrition. Using the ¹⁵N‐nitrogenenrichment method, the amount of nitrogen contributed by epiphytes to shrimp nutrition over 24 h could be determined. This method showed that nitrogen from epiphytes was assimilated by shrimp. ¹⁵N‐enrichment methods provided a more accurate alternative to natural abundance techniques, particularly when the stable isotope signals ofthe food sources are similar. This experiment hasshown the benefits in providing substrates for P.esculentus in high‐density rearing systems to provide an additional food source for shrimp.     

Re-Visiting Calcium Concentration and Distribution in Apple Fruit (Malus domestica Borkh.)

Distribution of calcium in the apple has been quantified using mineral analyses of fruit sections during the mid-1900s by various researchers. Most of the work was done either at harvest, or after storage. We used Proton-induced X-ray spectrometry (PIXE) and Scanning Electron Microscopy to correlate Ca distribution in apples to results obtained from mineral analyses (MA). For fruit at harvest transverse distribution of Ca in ‘Braeburn’ apples determined by PIXE confirmed similar analyses with MA. It was not possible to establish a significant relationship between the total Ca concentration determined by PIXE and soluble Ca concentration from MA in this paper, either at harvest, or 80 days after full bloom (dafb). A significant correlation was found between PIXE and SEM results 80 dafb.     

highway stormwater runoff quality: development of surrogate parameter relationships

The development of relationships for predicting the impact of highway stormwater runoff is described. The predictive relationships are regression-based equations reflecting variations in the magnitude of the constituents of interest. The objective is to identify a subset of constituents that can be used as surrogates for the remaining constituents as a means of decreasing the costs of collection and measurement of highway stormwater runoff quality data. The Minnesota highway stormwater quality database complied in the late 1970's and early 1980's is employed in identifying the set of surrogate parameters. The findings indicate that total suspended solids, total dissolved solids, total volatile solids, and total organic carbon are effective surrogate parameters for numerous metals, ionic species, and nutrients. The findings also indicated that the developed ionic species constituent relationships are portable, while the metal and nutrient constituent relationships were limited to urban sites with similar environmental conditions. The development of these relationships represents a step towards remediating and preventing the problem of nonpoint source highway pollution.     

the effect of phosphate on the transformation of ferrihydrite into crystalline products in alkaline media

The presence of phosphate retards the transformation of ferrihydrite into crystalline products. Increasing phosphate from 0 to 1 mole % results in an order of magnitude decrease in the rate of transformation of ferrihydrite at pH 12. Levels of phosphate of ～1 mol % suppress the formation of goethite (α-FeO(OH)) and result in the formation of a product consisting ofη-Fe₂O₃. Higher levels of phosphate result in the ferrihydrite remaining amorphous, even after several hundred hours. Phosphate prevents formation of goethite by hindering the dissolution of ferrihydrite rather than by interfering with nucleation and growth of goethite in solution. The transformation rate of pure ferrihydrite is also strongly inhibited in the presence of dissolved phosphate. This is due to surface complexation. The transformation rate was measured at temperatures of 60 °C and 70 °C. The rate of transformation was found to be described by either (i) a solid-state reaction equation for powdered compacts or (ii) a zero-order reaction controlled by desorption. The transformation of the ferrihydrite matrix was accompanied by the loss of the phosphate trace component. X-ray diffraction indicates that no solid solution involving phosphate substitution intoη-Fe₂O₃ is formed. Transmission electron microphotographs of the original precipitates containing phosphate confirm the presence of the phosphate and demonstrate its involvement in linking together extremely small particles of ferrihydrite.     

Treatment and prevention of intestinal parasite-associated disease.

Since 1917, only 11 new endoparasiticides have been developed for the horse, of which five chemical classes are in common use. The selection pressure of frequent administration of deworming doses for parasite control programs has been associated with the development of resistance of small strongyle parasites to the effects of benzimidazoles and pyrantel salts. Against the background of the inevitability of the occurrence of ivermectin/moxidectin resistance, responsible use of equine anthelmintics based on the clinical pharmacology of the compounds and the biology/epidemiology of intestinal parasites is a major issue for equine clinicians. The evidence base for the recommendations for treatment and control of equine intestinal parasites is sparse, however, and few robust data exist from controlled clinical trials to validate current guidelines.     

Antibody titres to lamb rotavirus in colostrum and milk of vaccinated ewes.

Ewes were vaccinated two to three weeks prior to mating with a formalin-treated preparation of lamb rotavirus. The colostrum and milk produced by vaccinated ewes after the subsequent pregnancy were shown to contain significantly higher titres of antibody to the virus than did mammary secretions from non-vaccinates. The virus neutralising antibody activity was associated with IgG in both colostrum and milk. However, IgG concentrations in the mammary secretions of vaccinates and non-vaccinates did not differ. It is suggested that vaccination of the dam may be of value in protecting the suckled neonatal lamb against rotavirus infection.