Can agricultural cultivation methods influence the healthfulness of crops for foods

The aim of the current study was to investigate if there are any health effects of long-term consumption of organically grown crops using a rat model. Crops were retrieved over two years from along-term field trial at three different locations in Denmark, using three different cultivation systems(OA, organic based on livestock manure; OB, organic based on green manure; and C, conventional with mineral fertilizers and pesticides)with two field replicates. The cultivation system had an impact on the nutritional quality, affecting γ-tocopherol, some amino acids, and fatty acid composition. Additionally, the nutritional quality was affected by harvest year and location. However, harvest year and location rather than cultivation system affected the measured health biomarkers. In conclusion, the differences in dietary treatments composed of ingredients from different cultivation systems did not lead to significant differences in the measured health biomarkers, except for a significant difference in plasma IgGl evels

Microorganisms on macrophyte debris : biodegradation and its implication in the food web

In a Mediterranean seagrass ecosystem (Posidonia oceanica ) around Ischia (Gulf of Naples) an attempt was made to study the fate of Posidonia derived particulate matter in wrack beds around and within the seagrass stands, on the shore and in the water column. Changes in total soluble carbohydrate concentrations from green and brown parts within one leaf vary from 70.7 to 25.7 mg.g-1 dry weight. Minimum values of 0.2 mg.g-1 dry weight consisting mainly of saccharose are detected for brown wrack particles. All other components found in green leaf parts, e.g. fructose, glucose and myo-inositol probably leach rapidly into the water or are transported into the rhizome prior to the loss of the brown leaf region. Only in the rhizome the trisaccharide raffinose was detected in addition to the components found in the leaves. The importance of the brown leaf fraction as a substrate for microheterotrophs is indicated by bacterial densities up to 4 x 104 cells.mm-2. This is correlated with nitrogen and carbon values, showing a decreasing C/N ratio with decreasing particle size, but increasing O2 uptake with maximum values of 10 mg.g-1.h-1 for the particle size fraction of 0.1 - 1 mm. The role of the brown dead Posidonia derived leaf tractions as energy source for consumers is discussed and attempts are made to redefine the terms "debris" and „detritus"

Descriptors of Posidonia oceanica meadows: Use and application

The conservation of the coastal marine environment requires the possession of information that enables the global quality of the environment to be evaluated reliably and relatively quickly. The use of biological indicators is often an appropriate method. Seagrasses in general, and Posidonia oceanica meadows in particular, are considered to be appropriate for biomonitoring because of their wide distribution, reasonable size, sedentary habit, easy collection and abundance and sensitivity to modifications of littoral zone. Reasoned management, on the scale of the whole Mediterranean basin, requires standardized methods of study, to be applied by both researchers and administrators, enabling comparable results to be obtained. This paper synthesises the existing methods applied to monitor P. oceanica meadows, identifies the most suitable techniques and suggests future research directions. From the results of a questionnaire, distributed to all the identified laboratories working on this topic, a list of the most commonly used descriptors was drawn up, together with the related research techniques (e.g. standardization, interest and limits, valuation of the results). It seems that the techniques used to study meadows are rather similar, but rarely identical, even though the various teams often refer to previously published works. This paper shows the interest of a practical guide that describes, in a standardized way, the most useful techniques enabling P. oceanica meadows to be used as an environmental descriptor. Indeed, it constitutes the first stage in the process. (c) 2005 Elsevier Ltd. All rights reserved.Peer reviewe

The Contribution of Occult Precipitation to Nutrient Deposition on the West Coast of South Africa

The Strandveld mediterranean-ecosystem of the west coast of South Africa supports floristically diverse vegetation growing on mostly nutrient-poor aeolian sands and extending from the Atlantic Ocean tens of kilometers inland. The cold Benguela current upwelling interacts with warm onshore southerly winds in summer causing coastal fogs in this region. We hypothesized that fog and other forms of occult precipitation contribute moisture and nutrients to the vegetation. We measured occult precipitation over one year along a transect running inland in the direction of the prevailing wind and compared the nutrient concentrations with those in rainwater. Occult deposition rates of P, N, K, Mg, Ca, Na, Al and Fe all decreased with distance from the ocean. Furthermore, ratios of cations to Na were similar to those of seawater, suggesting a marine origin for these. In contrast, N and P ratios in occult precipitation were higher than in seawater. We speculate that this is due to marine foam contributing to occult precipitation. Nutrient loss in leaf litter from dominant shrub species was measured to indicate nutrient demand. We estimated that occult precipitation could meet the demand of the dominant shrubby species for annual N, P, K and Ca. Of these species, those with small leaves intercepted more moisture and nutrients than those with larger leaves and could take up foliar deposits of glycine, NO3-, NH4 + and Li (as tracer for K) through leaf surfaces. We conclude that occult deposition together with rainfall deposition are potentially important nutrient and moisture sources for the Strandveld vegetation that contribute to this vegetation being floristically distinct from neighbouring nutrient-poor Fynbos vegetation

Seasonal variations of virus abundance and viral control of the bacterial production in a backwater system of the danube river

The abundance of virus-like particles in a backwater system of the Danube River covered a range of 1.2 x 10(sup7) to 6.1 x 10(sup7) ml(sup-1) from 1992 to 1993. Measurements of head diameters for these particles, all of which were presumed to be viruses, led to four defined size classes, ranging from &lt;60 nm to &gt;150 nm. The 60- to &lt;90-nm size class contained the largest fraction of total particles (41%), followed by the 90- to &lt;150-nm size class (33%). The frequency of size classes was not significantly different between the two years. The frequency of bacteria with mature phages ranged from 1 to 4% over the seasons, with mean burst sizes ranging from 17 to 36 phage per host cell. Among the bacterial morphotypes, rods and vibrios were the major host systems for phages, while coccoid and filamentous cells were considered negligible. Counts from transmission electron microscopy and acridine orange direct counts confirmed that rods and vibrios accounted for 85 to 95% of the bacterial population over the seasons. Virus decay experiments showed lower decay rates for temperatures between 5 and 15(deg)C (52 to 70% of the virus population remained) relative to 18 and 25(deg)C (31 to 51% of the virus remained). Bacterial production measurements, performed at the same time and under the same conditions as decay experiments, allowed us to estimate virus-induced death rates, which ranged from 15.8 to 30.1% over the year, with an average of 20% viral control of the bacterial production. Considering that mature phage particles are visible only in the last phase of the latent period and using a mean conversion factor of 5.4 from the literature, based on descriptions of various phage host systems to relate the percentage of visibly infected cells to the total percentage of the bacterial community that is phage infected, we estimate that some 5.4 to 21.6% of the bacterial population is infected with viruses. This would imply that virus-induced death rates of bacteria range from 10.8 to 43.2%. The data on virus-induced bacterial mortality obtained by both the viral decay method and the determination of the frequency of infected cells are compared and discussed.</jats:p