Characterization of phosphorus fractions in the sediments of a tropical intertidal mangrove ecosystem

Solid phases of phosphorus fractions in the surface and core sediments were studied to understand the biogeochemical cycling and bioavailability of phosphorus in the Pichavaram intertidal mangrove sediments of India. Total P in surface and core sediments ranged between 451–552 and 459–736 μg g⁻¹ respectively and Fe bound P was the dominant fraction. Low levels of Fe bound P in the mangrove zone than the two estuarine zones may be because of high salinity inhibition of phosphate adsorption onto the Fe-oxides/hydroxides. Post-depositional reorganization of P was observed in surface sediments, converting organic P and Fe bound P into the authigenic P. High levels of organic P in the mangrove zone is primarily due to intensive cycling and degradation of organic matter and adsorption of phosphate on the organic molecules. The burial rates and regeneration efficiency of P in the intertidal mangrove ecosystem ranged from 5.41 to 7.27 μmol P cm⁻² year⁻¹ and 0.122 to 0.233 μmol P cm⁻² year⁻¹, respectively. High burial efficiency (≈99%) of P proves the earlier observation of limiting nature of P for the biological productivity. Further, bioavailable P (exchangeable P + Fe bound P + organic P) constituted a considerable proportion of sedimentary P pool of which an average accounted for 55 and 50% in surface and core sediments respectively. The results indicate that significant amount of P is locked in sediments in the form of authigenic P and detrital P which makes P as a limiting nutrient for the biological productivity.     

Development and prospective validation of a model for predicting weaning in chronic ventilator dependent patients

Background

HTLV-I infection has been linked to lung pathology and HTLV-II has been associated with an increased incidence of pneumonia and acute bronchitis. However it is unknown whether HTLV-I or -II infection alters pulmonary function.

Methods

We performed pulmonary function testing on HTLV-I, HTLV-II and HTLV seronegative subjects from the HTLV outcomes study (HOST), including vital capacity (VC), forced expiratory volume in one second (FEV₁), and diffusing lung capacity for carbon monoxide (DLCO) corrected for hemoglobin and lung volume. Multivariable analysis adjusted for differences in age, gender, race/ethnicity, height and smoking history.

Results

Mean (standard deviation) pulmonary function values among the 257 subjects were as follows: FVC = 3.74 (0.89) L, FEV₁ = 2.93 (0.67) L, DLCO_corr = 23.82 (5.89) ml/min/mmHg, alveolar ventilation (VA) = 5.25 (1.20) L and DLCO_corr/VA = 4.54 (0.87) ml/min/mmHg/L. There were no differences in FVC, FEV1 and DLCO_corr/VA by HTLV status. For DLCO_corr, HTLV-I and HTLV-II subjects had slightly lower values than seronegatives, but neither difference was statistically significant after adjustment for confounding.

Conclusions

There was no difference in measured pulmonary function and diffusing capacity in generally healthy HTLV-I and HTLV-II subjects compared to seronegatives. These results suggest that previously described HTLV-associated abnormalities in bronchoalveolar cells and fluid may not affect pulmonary function.     

A checklist of the termites of Ethiopia with a review of their biology, distribution and pest status

Records of termites from Ethiopia, including those obtained during recent visits, indicate 61 species belonging to 25 genera and four families. The fauna includes Pan-African, East African, and West African or sub-Sahelian species, a single Palaearctic species and ten species endemic to Ethiopia and the neighbouring region. The distributions within Ethiopia of at least some of the species correlate with their overall African distributions; altitude plays an important part. The biology and pest status of each species are discussed. Macrotermitinae, especially Macrotermes sp. and Microtermes spp. constitute the greatest threat to agriculture, while a range of species are potentially damaging to wooden structures.

Résumé

Les relevés de termites d'Ethiopie, y compris ceux obtenus lors de visites récentes rapportent 61 espkces appartenant à 25 genres et à 4 familles. La faune inclut des espèces pan-africaines, est-africaines, ouest-africaines ou sub-sahéliennes, une seule espèce paléarctique et dix espèces endémiques à 1'Ethiopie et aux régions voisines. La distribution à I'intérieur de 1'Ethiopie d'au moins quelques espèces s'accorde avec leur distribution dans toute I'Afrique, l'altitude joue un rôle important. La biologie et le caractère de nuisance de chaque espèce sont discutés. Les Macroterminae, et spécialement Macrotermes spp. et Microtermes spp. représentent la plus grande menace pour l'agriculture, alors qu'une série d'espèces pourraient causer des dommages aux structures en bois.     

Spatial distribution of vectors of Ross River virus and Barmah Forest virus on Russell Island, Moreton Bay, Queensland

Abstract We used a network of 20 carbon dioxide- and octenol-supplemented light traps to sample adult mosquitoes throughout Russell Island in southern Moreton Bay, south-east Queensland. Between February and April 2001, an estimated 1365 564 adult female mosquitoes were collected. In contrast to an average catch of 9754 female mosquitoes per trap night on Russell Island, reference traps set on Macleay Island and on the mainland returned average catches of 3172 and 222, respectively. On Russell Island, Ochlerotatus vigilax (Skuse), Coquillettidia linealis (Skuse), Culex annulirostris Skuse and Verrallina funerea (Theobald), known or suspected vectors of Ross River (RR) and/or Barmah Forest (BF) viruses, comprised 89.6% of the 25 taxa collected. When the spatial distributions of the above species were mapped and analysed using local spatial statistics, all were found to be present in highest numbers towards the southern end of the island during most of the 7 weeks. This indicated the presence of more suitable adult harbourage sites and/or suboptimal larval control efficacy. As immature stages and the breeding habitat of Cq. linealis are as yet undescribed, this species in particular presents a considerable impediment to proposed development scenarios. The method presented here of mapping the numbers of mosquitoes throughout a local government area allows specific areas that have high vector numbers to be defined.     

The Response of Groundnut (Arachis hypogaea L.) to Timing of Irrigation

A timing-of-irrigation experiment was conducted in controlled-environmentglasshouses, in which a finite quantity of water was appliedto four stands of groundnut (Arachis hypogaea L.) at differentstages of the growing season. Irrigation schedules were broadlydivided into two periods; sowing to pod initiation and pod initiationto final harvest. Within these periods two levels of soil moisturedeficit were imposed by withholding or applying limited amountsof irrigation at regular intervals. Shoot dry matter yields were hardly affected but pod yieldswere more than 4-fold lower in early- than in late-irrigatedstands. Thermal time was used to separate the effects of temperatureand water stress on developmental processes. The degree-dayrequirement for peg initiation was similar in all treatmentsbut late-irrigation delayed pod development by about 200 °Cd.The effect of timing of irrigation on pod yield operated mainlythrough its influence on the duration of pod production, whichwas closely linked to the rate and duration of canopy expansionlate in the season. The insensitivity of pod yield to earlymoisture deficits reflected the extreme plasticity of growthand development in groundnut, since most processes resumed ratessimilar to the pre-stress levels in early-irrigated stands oncestress was released. Key words: Groundnut, irrigation, growth, development