Batch and continuous biogas production from grass silage liquor

Herein batch and continuous mesophilic anaerobic digestion of grass silage liquor was studied. The continuous process was carried out in Armfield digesters with an OLR ranging from 0.851 to 1.77 kg COD m⁻³ day⁻¹. The effect of recirculation of effluent from the digester was investigated using different OLRs of grass silage liquor feed. These results showed that as the OLR increased, the methane yield decreased for the reactor with no recycle and increased for the reactor with recycle. However, the COD removal for both digesters was nearly the same at the same OLR. Overall these studies show that grass silage liquor can produce a high quality methane steam between 70% and 80% and achieve methane yields of 0.385 m³ kg⁻¹ COD.     

Insights into the Management of Large Carnivores for Profitable Wildlife-Based Land Uses in African Savannas

Large African predators, especially lions (Panthera leo) and leopards (Panthera pardus), are financially valuable for ecotourism and trophy hunting operations on land also utilized for the production of other wildlife species for the same purpose. Predation of ungulates used for trophy hunting can create conflict with landholders and trade off thus exists between the value of lions and leopards and their impact on ungulate populations. Therefore productionist and conservation trade-offs are complexly graded and difficult to resolve. We investigated this with a risk-benefit analysis on a large private wildlife production area in Zimbabwe. Our model showed that lions result in substantial financial costs through predation on wild ungulates that may not be offset by profits from hunting them, whereas the returns from trophy hunting of leopards are projected to exceed the costs due to leopard predation. In the absence of additional income derived from photo-tourism the number of lions may need to be managed to minimize their impact. Lions drive important ecological processes, but there is a need to balance ecological and financial imperatives on wildlife ranches, community wildlife lands and other categories of multiple use land used for wildlife production. This will ensure the competitiveness of wildlife based land uses relative to alternatives. Our findings may thus be limited to conservancies, community land-use areas and commercial game ranches, which are expansive in Africa, and should not necessarily applied to areas where biodiversity conservation is the primary objective, even if hunting is allowed there.     

Regional and local effects on reproductive allocation in epicormic and lignotuberous populations of <Emphasis Type="Italic">Banksia menziesii</Emphasis>

Reproductive allocation (RA) is a measure of how resources (biomass, nutrients) are partitioned between reproductive structures and the rest of the plant. For plants that resprout after fire, the percentage of resources allocated to reproduction may vary depending on their resprouting ability. Our study examines the percentage RA (biomass, N, P, K) and nutrient content of current season’s growth in southern (Swan Coastal Plain) epicormic and northern (Eneabba Plain) lignotuberous resprouter populations of Banksia menziesii (Proteaceae), a species endemic to nutrient-impoverished sandplains of southwestern Australia. Within each population, plants along road edges were compared with plants not associated with road edges. There was no difference in total nutrient content of current year’s growth between both resprouting types, except that total K in the shoots of lignotuberous populations was >2 times that in the epicormic populations. Non-road lignotuberous plants allocated twice the biomass, N and P, and 13.5 times the K, to reproduction as non-road epicormic plants. Lignotuberous populations had the highest RA (17–34% of biomass, N, P, K), with non-road epicormic populations the lowest RA (3–15%). This can be viewed as an adaptive (ultimate) response to the poorer postfire survival and recruitment conditions where the lignotuberous populations occur. Total biomass and nutrient content of road-edge plants was 2–3 times that of non-edge plants. Lignotuberous populations in both road positions allocated the same fraction of biomass, N and P to reproduction, whereas road-edge populations allocated 10% less K than non-road. Road-edge epicormic populations allocated 5–10% more biomass, N, P and K to reproduction than non-road populations. This can be viewed as an ecophysiological (proximate) response to the better growing conditions created by the roadways that may also ultimately have an adaptive explanation.     

Mice and Monkeys as Assay Animals for Clostridium perfringens Food Poisoning

Spores and vegetative cells of Clostridium perfringens, in combination with meat or starch paste, sterile culture filtrates, lecithinase, and phosphorylcholine, were administered to mice and rhesus monkeys in an attempt both to evaluate the animals as test agents and, if possible, to elucidate the active factors producing food-poisoning symptoms caused by this organsim. Some of the preparations were administered to the monkeys by stomach tube; others, in gelatin capsules which were treated with formaldehyde so that the release of their contents was delayed and presumably reached the intestines of the animals. Any changes in intestinal passage times and in consistency of stools of the animals were observed, and the counts of C. perfringens in the feces of the monkeys previous and subsequent to treatment were recorded. The results obtained were inconclusive. Diarrhea occurred only relatively infrequently in both species, regardless of the substance fed or the mode of administration. The changes in intestinal passage times were not great, although in the monkeys there appeared to be a slight trend toward reduction as the magnitude of the bacterial load increased. Phosphorylcholine appeared to have little, if any, effect in reducing intestinal passage time of mice or monkeys. No procedures explored in these experiments could be said to be satisfactory as a means of animal assay for food poisoning strains of C. perfringens since typical symptoms did not appear with regularity.     

Avian fruit preferences across a Puerto Rican forested landscape: pattern consistency and implications for seed removal

Avian fruit consumption may ensure plant reproductive success when frugivores show consistent preference patterns and effectively remove and disperse seeds. In this study we examined avian fruit preferences and their seed-removal services at five study sites in north-central Puerto Rico. At each site, we documented the diet of seven common fruit-eating avian species from February to September 1998. Using foraging observations and area-based estimates of fruit abundance, we examined preference patterns of birds. We found that 7 out of 68 fleshy-fruited plant species were responsible for most of the fruit diet of birds. Seventeen plant species were preferred and four of them were repeatedly preferred across several study sites and times by at least one avian species. Preferred plant species comprised a small percentage of fleshy fruits at each site (<15% in four out of five study sites), but showed extended phenology patterns. The quantity of seeds removed by frugivore species was not strictly related to preferences. Some frugivores showing no preference could effectively remove more seeds from plants at some locations than species exhibiting constancy in their patterns of preference. Only two frugivores, Euphonia musica and Vireo altiloquous, removed most of the seeds of plants for which they exhibited repeated preference across the landscape. Preference patterns, particularly those exhibiting consistency in space and time for plant species having prolonged fruiting periods, may have important mechanistic consequences for the persistence, succession, and regeneration of tropical plant communities.     

Recent introduction of an allodapine bee into Fiji: A new model system for understanding biological invasions by pollinators

Morphology‐based studies have suggested a very depauperate bee fauna for islands in the South West Pacific, and recent genetic studies since have indicated an even smaller endemic fauna with many bee species in this region resulting from human‐aided dispersal. These introduced species have the potential to both disrupt native pollinator suites as well as augment crop pollination, but for most species the timings of introduction are unknown. We examined the distribution and nesting biology of the long‐tongued bee Braunsapis puangensis that was first recorded from Fiji in 2007. This bee has now become widespread in Fiji and both its local abundance and geographical range are likely to increase dramatically. The impacts of this invasion are potentially enormous for agriculture and native ecosystems, but they also provide opportunities for understanding how social insect species adapt to new environments. We outline the major issues associated with this recent invasion and argue that a long‐term monitoring study is needed.     

The non-photochemical reduction of plastoquinone in leaves

Although it is generally assumed that the plastoquinone pool of thylakoid membranes in leaves of higher plants is rapidly oxidized upon darkening, this is often not the case. A multiflash kinetic fluorimeter was used to monitor the redox state of the plastoquinone pool in leaves. It was found that in many species of plants, particularly those using the NAD-malic enzyme C₄ system of photosynthesis, the pool actually became more reduced following a light to dark transition. In some Amaranthus species, plastoquinone remained reduced in the dark for several hours. Far red light, which preferentially drives Photosystem I turnover, could effectively oxidize the plastoquinone pool. Plastoquinone was re-reduced in the dark within a few seconds when far red illumination was removed. The underlying mechanism of the dark reduction of the plastoquinone pool is still uncertain but may involve chlororespiratory activity.Abbreviations apparent F_o observed fluorescence yield after dark adaptation - F_m maximum fluorescence when all Q_A is fully reduced - F_o minimum fluorescence yield when Q_A is fully oxidized and non-photochemical quenching is fully relaxed - F_s steady state fluorescence yield - PPFD photosynthetic photon flux density - PQ plastoquinone - Q_A primary quinone acceptor of the Photosystem II reaction center - Q_B secondary quinone acceptor to the Photosystem II reaction center - F F_m minus F_s     

Cross sectional survey of socioeconomic variations in severity and mechanism of childhood injuries in Trent 1992-7

ObjectiveTo determine the relation between morbidity from injury and deprivation for different levels of injury severity and for different injury mechanisms for children aged 0-14 years.DesignCross sectional survey of routinely collected hospital admission data for injury 1992-7.Setting862 electoral wards in Trent Region.Subjects21 587 injury related hospital admissions for children aged 0-4 years and 35 042 admissions for children aged 5-14.ResultsBoth total number of admissions for injury and admissions for injuries of higher severity increased with increasing socioeconomic deprivation. These gradients were more marked for 0-4 year old children than 5-14 year olds. In terms of injury mechanisms, the steepest socioeconomic gradients (where the rate for the fifth of electoral wards with the highest deprivation scores was ⩾3 times that of the fifth with the lowest scores) were for pedestrian injuries (adjusted rate ratio 3.65 (95% confidence interval 2.94 to 4.54)), burns and scalds (adjusted rate ratio 3.49 (2.81 to 4.34)), and poisoning (adjusted rate ratio 2.98 (2.65 to 3.34)).ConclusionThere are steep socioeconomic gradients for injury morbidity including the most common mechanisms of injury. This has implications for targeting injury prevention interventions and resources.

What is already known on this topic?

There is a steep socioeconomic gradient for injury related mortalityThere is conflicting evidence regarding the socioeconomic gradient for injury morbidity, particularly with respect to different injury severity and injury mechanisms

What this study adds

A socioeconomic gradient for injury morbidity exists in children aged <15 years, particularly in those aged <5, which persist for different measures of injury severityThe socioeconomic gradient for injury mechanisms is steepest for pedestrian injuries, burns and scalds, and poisoning, which has implications for targeting injury prevention strategies