Major declines in the abundance of vultures and other scavenging raptors in and around the Masai Mara ecosystem, Kenya

Vulture population declines have been noted in West and Southern Africa, but have not been assessed in East Africa. Roadside transects conducted in 1976 and 1988 were compared with surveys done from 2003–2005 in and around Masai Mara National Reserve, Kenya. Staggering declines in abundance were found for seven of eight scavenging raptors surveyed. No Egyptian vultures were seen during recent transects. We compared trends between the ungulate migration and non-migration season among three land use types (reserve, buffer, and grazed) and among the species surveyed to establish the causes of declines in scavenging raptors. Large declines during the ungulate migratory period suggest that most scavenging raptor species are declining well beyond the area of study. For all species, except Hooded vultures, substantial declines outside of the reserve indicate an important role of land use change in causing observed declines. In addition, significant declines of populations of Gyps species in the reserve itself, especially during the migration season, provide evidence that human activities occurring in other parts of the species’ range such as poisoning of carcasses may be causing their decline. Declines found in this study suggest that at a minimum African white-backed, Rüppell’s, and Hooded vultures should be relisted as Vulnerable. Management actions that limit land use change around the reserve combined with a countrywide ban on carbamate pesticides will be important for conserving keystone members of the scavenging guild. Future research should further examine possible causes of these declines and quantify the effect of reduced scavenging raptor abundance on scavenging efficiency.     

Soil microbial communities resistant to changes in plant functional group composition

The soil community is an often ignored part of research which links plant biodiversity and ecosystem functioning despite their influence on numerous functions such as decomposition and nutrient cycling. Few consistent patterns have been detected that link plant and soil community composition. We used a removal experiment in a northern Canadian grassland to examine the effects of plant functional group identity on soil microbial community structure and function. Plant functional groups (graminoids, legumes and forbs) were removed independently from plots for five growing seasons (2003-2007) and in the fifth year effects on the soil microbial community were examined using substrate-induced respiration (SIR - a measure of metabolic diversity) and phospholipid fatty acid analysis (PLFA - a measure of microbial community composition). Removal treatments were also crossed with both a fertilizer treatment and a fungicide treatment to determine if effects of functional group identity on the soil community were context dependent. Plant functional group identity had almost no effect on the soil microbial community as measured by either SIR or PLFA. Likewise, soil properties including total carbon, pH, moisture and nutrients showed a limited response to plant removals in the fifth year after removals. We found a direct effect of fertilizer on the soil community, with fertilized plots having decreased metabolic diversity, with a decreased ability to metabolize amino acids and a phenolic acid, but there was no direct soil microbial response to fungicide. We show that in this northern Canadian grassland the soil microbial community is relatively insensitive to changes in plant functional group composition, and suggest that in northern ecosystems, where plant material is only slowly incorporated into the soil, five growing seasons may be insufficient to detect the impact of a changing plant community on the soil microbes.     

Uncommon associations in target resistance among French populations of Myzus persicae from oilseed rape crops

Within the framework of a molecular exploration of target resistance in populations of Myzus persicae on oilseed rapes in France, (1) the S431F mutation (coding gene ace2), although previously reckoned to be rare, revealed to be frequent, (2) M918L (phenotypically characterised) and L932F (both on para) were found for the first time in M. persicae, and (3) a linkage was revealed between M918L and S431F. While until recently populations developing on French oilseed rapes were dominated by genotypes possessing pyrethroid target resistance and esterase overproduction, to date a different type of dominating genotype, equipped with carbamate and pyrethroid target resistance, seems to be invading such fields.     

Ion-pair reverse phase liquid chromatographic determination of sodium acifluorfen in feed

Ion-pair reverse phase liquid chromatography (LC) and UV detection at 280 nm have been used to determine sodium acifluorfen (sodium-5-[2-chloro-4-(trifluoromethyl)-phenoxy]-2-nitrobenzoate), an experimental diphenyl ether herbicide, in dog feed. Sodium-5-(2,4-dichlorophenoxy)-2-nitrobenzoate is used as the internal standard. The feed is homogenized in 0.01N HCl, followed by ethyl acetate extraction, and centrifugation. The organic layer is removed and evaporated and the residue is reconstituted in methanol and filtered before LC analysis (mobile phase methanol-water (58 + 42), 0.005M in tetrabutylammonium phosphate and 0.045M in (NH4)2HPO4, at pH 7.4). The ion-pair technique offers a high degree of control over the retention characteristics of the herbicide and internal standard. The use of the internal standard permits precise and accurate quantitation and substantially reduces analysis time compared with the external standard method.     

Isozyme Banding Pattern and Estimation of Genetic Diversity among Guinea Grass Germplasm

Isozyme banding pattern was studied in Guinea grass (Panicum maximum Jacq.), a widely cultivated grass having good fodder value. Similarity among 63 accessions collected from diverse sources was worked out using five enzyme systems (SOD, GOT, ACP, Esterase and Peroxidase) following horizontal starch gel electrophoresis. Biochemical markers such as isozymes are useful supplements in identifying the genetic variation present in any crop. A total of 35 clear and unambiguous bands were used for analysis of which 8 bands were monomorphic. Polymorphism exhibited by 27 bands from all five enzyme systems indicate presence of considerable diversity in this species. The dendrogram generated after UPGMA and SAHN cluster analysis using Jaccard genetic distance showed that 63 accessions from diverse geographical locations could be grouped in three main clusters, of which two could further be divided into sub-clusters. Although the clusters comprised members from different locations, most of the accessions from similar geographical locations tended to cluster in same group.     

Determination of a chemical basis of air-pollution stress in wood of mature white pine trees in the susceptive forest ecosystems

This paper describes a pilot investigation dealing with changes in chemical composition of wood in pollution-stressed white pine trees, taken from two forested ecosystems of Southern Ontario, Canada. The implications of this research lie in a much needed search for a potential bloindicator of a pre-decline, incipient-stress induced (and/or contributed by) the air-pollutants.     

δ34S variations in vegetation and soil exposed to intense biogenic sulphide emissions near Paige mountain,N.W.T., Canada

Sulphur isotope abundances demonstrate that natural emissions of biogenic H₂S and its oxidation products from springs near Paige Mountain, N.W.T., Canada, can be incorporated into surrounding soil and vegetation. δ³⁴S values as low as ? 33‰ for soil and vegetation are the result of dominant uptake of biogenic atmospheric compounds. In contrast, vegetation on a gypsum outcrop remote from the springs, has δ³⁴S values as high as + 26‰ indicating nearly exclusive derivation of S from the soil. Near the springs, soil with vegetative cover is less depleted in ³⁴S than soil lacking cover. Lower needles on a Black Spruce were found to be less depleted in ³⁴S than the upper needles. These observations suggest that upper foliage exerts a canopy effect on lower foliage and in turn, interception by vegetation reduces the flux of atmospheric S compounds to the soil. Clearly, natural emissions of S compounds can interfere in studies of long range transport of industrial emissions; S isotope analyses might identify such interferences and reduce the chance of misinterpretation.     

Contamination environnementale par les métaux et maladie de Parkinson

Parkinson's disease (PD) has been proposed to result from the interaction of aging and environment in susceptible individuals. The prevalence of PD in Quebec was 84 per 100 000 in 1985. The regional variation observed has been linked with several environmental factors. We intended to verify the existence of a relation between the development of PD with exposure to 3 metal pollutants: Fe, Mn, and Al. The choice of these metals rests on their potential presence in the environment caused by the industrial activity in the region studied, and on the fact that it theoretically favors the prevalence of the illness. Environmental exposure to these metals and the resulting risks were evaluated using red spruce as a bio-indicator. The metal concentrations in tree rings were determined by neutron activation analysis. These concentrations permitted a temporal estimation of contamination in each of the territories studied, from 1938 to 1987. The risk of environmental exposure was assumed to be proportional to the concentration of the metal. The calculated risks combined with the history of residence allowed a comparison between parkinsonians and controls. It appeared that environmental exposure to the metals was not significantly different between those two groups.     

Dynamics of microbial biomass and nitrogen supply during primary succession on blastfurnace slag dumps in dry tropics

This paper reports the role of microbial biomass in the establishment of N pools in the substratum during primary succession (till 40-year age) in Blastfurnace Slag Dumps, an anthropogenically created land form in the tropics. Initially in the depressions in the slag dumps fine soil particles (silt+clay) accumulate, retaining moisture therein, and providing microsites for the accumulation of microbial biomass. In all sites microbial biomass showed distinct seasonality, with summer-peak and rainy season-low standing crops. During the summer season microbial biomass C ranged from 18.6 μg g⁻¹ in the 1-year old site to ca. 235 μg g⁻¹ in the 40-year old site; correspondingly, microbial biomass N ranged from 1.22 to 40 μg g⁻¹. On sites 2.5-years of age and younger, the microbial biomass N content accounted for more than 50% of the organic N in the soil, whereas the proportion of microbial biomass N was ca. 7% of organic N in 40-year old site. The strong correlation between microbial biomass and total N in soil indicated a significant role of microbes in the build-up of nitrogen during the initial stages of succession in the slag dumps. Though the organic N pool in the soil was low (594 mg kg⁻¹) even after 40 years of succession, the available N (NH₄-N and NO₃-N) contents in the soil were generally high through the entire age series (ca. 16-32 μg g⁻¹) during the rainy season (which supports active growth of the herbaceous community). The high mineral-N status on the slag dump was related with high N-mineralization rates, particularly in the young sites (20.6 and 13.9 μg g⁻¹ month⁻¹ at 1 and 2.5-year age). We suggest that along with the abiotic factors having strong effect on ecosystem functioning, the microbial biomass, an important biotic factor, shows considerable influence on soil nutrient build-up during early stages of primary succession on the slag dumps. The microbial biomass dynamics initiates biotic control in developing slag dumps ecosystem through its effect on nitrogen pools and availability.