Abundance,perceptions and utilizations of termite mounds in Cambodia

In the Lower Mekong Basin, paddy fields often appear as mosaics, with soil mounds covered by trees or other plants in a spotty distribution. These soil mounds are commonly named termite ‘lenticular mounds’ because termite bioturbation is considered to be at their origin. Termite mounds host a large diversity of animals and plants, increasing landscape patchiness. Because the preservation of these islands of biodiversity is threatened by modern agricultural practices, the aim of this study was to quantify their abundance and the services they provide to the local population. The abundance of mounds and their use by the population were quantified in a catchment in Cambodia. We found that mounds density reached ~2 mounds ha⁻¹. Interviews carried out within the catchment showed that most of the interviewees used mounds for increasing the fertility of their field and for the cultivation of rice and other plants (e.g. sponge gourd and pumpkin). In addition to their potential to increase plant productivity, the survey revealed that animals (rats and snakes), mushrooms and 13 plant species found on or in mounds were consumed by the population. In addition to potentially contributing to an increase in food diversity, mounds also impacted farmers' health by allowing access to 20 medicinal plant species and indirectly via a reduction in pesticide use. In conclusion, this study is the first attempt to quantify the large number of services provided by termite mounds in Cambodia. This increase in the knowledge of the diversity of environmental and socioeconomic services provided by termite mounds is likely to contribute to their preservation and provide a basis for the sustainable management of biodiversity in paddy fields in the Lower Mekong Basin region.     

Roads, fire and aggressive competitors: Determinants of bird distribution in subtropical production forests

Forestry practices such as fuel-reduction burning and maintenance of road networks can negatively impact avian assemblages, both directly by changing habitat structure and indirectly by creating conditions favorable for predators or competitors. The Brigalow Belt forests include some of the largest contiguous areas of native forest in the temperate and sub-humid zones of eastern Australia. Over 1 million ha of these forests are proposed to be converted from forestry to conservation tenure, yet the impacts on the avifauna of current and potential future forest management practices are not known. We investigated the influence of road edges and habitat type and structure on the avifauna of a 356 000 ha forest. Survey sites were either <50 m or >300 m from a road, and in either cypress pine Callitris glaucophylla forest, spotted gum Corymbia citriodora forest with a regenerating cypress pine/buloke Allocasuarina luehmannii understorey or spotted gum forest with an open understorey due to fuel-reduction burning. The avifauna differed significantly among vegetation types but not with proximity to a road, with the greatest differences between cypress pine and both types of spotted gum forest. The noisy miner Manorina melanocephala, an aggressive avian competitor, appears to be the factor mediating these assemblage-level differences. Noisy miners were rare in cypress pine forest but were three times more numerous than any other species in spotted gum forest. Spotted gum forest with a regenerating understorey had fewer noisy miners. Although total bird abundance was highest in open spotted gum forest, the species richness and abundance of passerines smaller than noisy miners was significantly lower in this forest type. Abundance of small passerines was eight times higher in sites where <3 noisy miners were recorded. Only one species, the eastern yellow robin, was influenced by proximity to a road edge. Cypress pine forest is potentially an important refuge for smaller birds. The results suggest that burning regimes that reduce regeneration of the cypress pine and buloke subcanopy in spotted gum forest potentially are exacerbating the problem of noisy miner domination of the avifauna.     

Determination of methylmercury in fish by headspace-gas chromatography with microwave-induced-plasma detection

Some additional experiments checking out the extraction method recently developed for the determination of MeHg in biological samples by Headspace Gas Chromatography with Microwave Induced Plasma atomic emission spectroscopy detection were performed. In this method, the MeHg is cleaved from the biological tissue by H₂SO₄ and by addition of iodoacetic acid converted to the iodide form. These reaction steps take place in a closed headspace vial. The H₂SO₄ concentration and the sample matrix have an important influence on the recovery of the MeHg from the sample and these effects are discussed. The method was then applied to the determination of MeHg in cod fish caught in the North Sea. Levels found ranged from 0.13 to 0.63 μg g⁻¹ dw with a mean of 0.33 μg g⁻¹ on the 25 samples analyzed. The total Hg content of these samples was also determined by Cold Vapour Atomic Absorption Spectrometry, and all data pooled ranged from 0.19 to 0.90 μg g⁻¹ with a mean of 0.40 μg g⁻¹. A study of the ratio MeHg/total Hg revealed that MeHg always constituted more than 60 % of the total Hg level, with a mean of 83 % on the 25 samples. The percentage MeHg did not increase or decrease markedly when the total Hg content increased. It could be concluded that these North Sea samples are not much contaminated by Hg and are surely suitable for consumption.     

The influence of livestock grazing and weed invasion on habitat use by birds in grassy woodland remnants

Remnants of native vegetation in regions dominated by agriculture are subject to degradation, especially by livestock grazing and weed invasion. Ground-foraging birds are amongst the most threatened bird groups in Australia, and these agents of degradation might be contributing to their decline by causing a reduction in food availability. We studied the foraging behaviour and microhabitat use of seven species of ground-foraging insectivores in south-eastern Australian buloke woodland remnants with native, grazed and weedy ground-layers. If birds must resort to using more energetically expensive prey-attack manoeuvres, or selectively use substrates and microhabitats that are less available in degraded habitats, then such degradation is likely to be negatively impacting on these species. We found evidence of a negative impact of one or both of these types of degradation on five of the seven bird species. Three species that employ a range of foraging manoeuvres to attack prey used potentially more energetically expensive aerial manoeuvres significantly more frequently in weedy remnants than in remnants with a native or grazed ground layer. Red-capped robins Petroica goodenovii and brown treecreepers Climacteris picumnus both selectively foraged near trees in grazed sites, and hooded robins Melanodryas cucullata, red-capped robins and willie wagtails Rhipidura leucophrys avoided foraging in microhabitats with a high percentage cover of exotic grasses in weedy sites. Brown treecreepers were also less likely to be present in weedy sites that had been protected from grazing than in either grazed or native sites. These results suggest that although grazing appears to have a detrimental impact on foraging habitat of ground-foraging birds, the exclusion of livestock grazing from previously disturbed buloke remnants alone is not adequate to restore habitat values for ground-foraging birds. A conservation strategy for this habitat type should consider the exclusion of heavy grazing from sites with an intact cryptogamic crust and the management of weeds in disturbed remnants, potentially through the use of carefully controlled light grazing.     

Threshold effect of eucalypt density on an aggressive avian competitor

General guidelines available to revegetation planners focus on the spatial context and dimensions of the revegetated site. However, site-specific habitat factors can have overarching importance for habitat value, especially where interactions with competitors or predators may play an important role. Current revegetation projects in Australia which aim to restore slow-growing buloke (Allocasuarina luehmannii) woodland, a threatened habitat important for bird conservation, usually include faster-growing eucalypts in plantings. This research aimed to identify whether eucalypt presence in buloke woodland facilitates invasion by the noisy miner (Manorina melanocephala), an aggressive competitor that is absent from pure buloke woodland. Birds were surveyed in buloke woodland remnants that contained eucalypts as a sub-dominant species at densities of 0-16 per ha. The probability of noisy miner presence in buloke woodland increased markedly where eucalypts were present at a density of approximately five per hectare. The presence of noisy miners resulted in a substantial difference in bird assemblage structure and composition. Small-bodied insectivorous birds which are experiencing population declines in southern Australia were recorded on average six times more often in transects without noisy miners (low-eucalypt density transects). Avian behaviour and habitat use was also altered, with birds flying more frequently in transects where noisy miners were present. A minor difference in habitat composition results in substantial degradation of the conservation value of non-eucalypt woodland in eastern Australia due to invasion by aggressive avian competitors. Revegetation and restoration practices should take into account the potential for such subtle floristic differences to result in substantial variation in conservation outcomes.     

Chemical and sensory evaluation of crude oil extracted from herring byproducts from different processing operations

Fish oils extracted from marinated herring (frozen and unfrozen) byproducts and maatjes herring byproducts were evaluated on their chemical and sensory properties. The obtained crude oils had very low content of copper (<0.1 mg/kg oil), and iron values were 0.8, 0.1, and 0.03 mg/kg oil, respectively, for oil from maatjes and frozen and fresh byproducts. For the maatjes oil, a much lower value was found for alpha-tocopherol compared to the other oils. Storage stability results showed that the oils behave differently. Secondary oxidation products were measured for fresh oil, while for the maatjes and frozen byproducts' oil, tertiary oxidation products were detected. Over storage time, the maatjes and frozen byproducts' oils became more intense in odor, correlating positively at the end with sensory attributes of train-oil, acidic, marine and fishy. The best correlation between sensory and chemical analyses was found for FFA and fishy off-odor (r = 0.781).     

Beekeeping management practices in southwestern Quebec

The growing number of honey bee colonies and beekeepers in Canada has led to a great diversity of beekeeping practices. All beekeeping operations, however, need to implement consistent management measures for the control of diseases. The objective of this study was to document the actual disease management practices of beekeeping productions in southwestern Quebec, Canada. A survey was conducted to describe management practices used by 15 beekeepers who own 1824 colonies in that area. Data were obtained by telephone interviews. When infectious diseases were suspected, beekeepers generally avoided using potentially toxic acaricides and chemical treatments associated with antimicrobial resistance and instead used preventive, physical or management methods, although laboratory diagnosis was rarely used. This study highlights the wide variety of operation sizes, activities, and disease management strategies among beekeepers in southwestern Quebec. It identifies the need to encourage the use of services available to them and to propose a standardized preventive medical approach for field veterinarians to avoid the spread of infectious diseases.     

Protective effects of 4-hydroxycinnamic ethyl ester derivatives and related dehydrodimers against oxidation of LDL: radical scavengers or metal chelators?

4-Hydroxycinnamate derivatives are known to be potent protectors against oxidation of low-density lipoproteins (LDL), via a combination of free radical scavenging and transition metal chelation. Through a series of 4-hydroxycinnamic ethyl ester derivatives and related 8-8 dehydrodimers, we have tried to bring out the structural requirements for radical scavenging and cupric ion chelation. We found that the monomeric compounds, except for highly lipophilic tert-butyl derivative 3, exhibited rather low radical scavenging properties. Furthermore, they did not chelate copper but, in contrast, reduced cupric ion to cuprous ion, affording the related 8-8 dehydrodimers, for which they could be considered as precursors in vitro. In the copper-dependent human LDL oxidation in vitro, the cyclic 8-8 dehydrodimer forms behaved essentially as efficient copper chelators, while related noncyclic 8-8 forms, which were found to be the best protectors, mainly acted as radical scavengers.