Biomineralogy of human urinary calculi (kidney stones) from some geographic regions of Sri Lanka

Kidney stones (urinary calculi) have become a global scourge since it has been recognized as one of the most painful medical problems. Primary causative factors for the formation of these stones are not clearly understood, though they are suspected to have a direct relationship to the composition of urine, which is mainly governed by diet and drinking water. Sixty nine urinary calculi samples which were collected from stone removal surgeries were analyzed chemically for their Na, K, Ca, Mg, Cu, Zn, Pb, Fe and phosphate contents. Structural and mineralogical properties of stones were studied by XRD and FT-IR methods. The mean contents of trace elements were 1348 mg kg⁻¹ (Na); 294 mg kg⁻¹ (K); 32% (Ca); 1426 mg kg⁻¹ (Mg); 8.39 mg kg⁻¹ (Mn); 258 mg kg⁻¹ (Fe); 67 mg kg⁻¹ (Cu); 675 mg kg⁻¹ (Zn); 69 mg kg⁻¹ (Pb); and 1.93% (PO₄³⁻). The major crystalline constituent in the calculi of Sri Lanka is calcium oxalate monohydrate. Principal component analysis was used to identify the multi element relationships in kidney stones. Three components were extracted and the first component represents positively correlated Na-K-Mg-PO₄³⁻ whereas the␣second components represent the larger positively weighted Fe–Cu–Pb. Ca–Zn correlated positively in the third component in which Mn–Cu correlated negatively. This study indicates that during the crystallization of human urinary stones, Ca shows more affinity towards oxalates whereas other alkali and alkaline earths precipitate with phosphates.Contribution from the Environmental Geology Research Group (EGRG), Department of Geology, University of Peradeniya, Sri Lanka.     

Effects of Selective Logging on Bat Communities in the Southeastern Amazon

Abstract:  Although extensive areas of tropical forest are selectively logged each year, the responses of bat communities to this form of disturbance have rarely been examined. Our objectives were to (1) compare bat abundance, species composition, and feeding guild structure between unlogged and low-intensity selectively logged (1–4 logged stems/ha) sampling grids in the southeastern Amazon and (2) examine correlations between logging-induced changes in bat communities and forest structure. We captured bats in understory and canopy mist nets set in five 1-ha study grids in both logged and unlogged forest. We captured 996 individuals, representing 5 families, 32 genera, and 49 species. Abundances of nectarivorous and frugivorous taxa (Glossophaginae, Lonchophyllinae, Stenodermatinae, and Carolliinae) were higher at logged sites, where canopy openness and understory foliage density were greatest. In contrast, insectivorous and omnivorous species (Emballonuridae, Mormoopidae, Phyllostominae, and Vespertilionidae) were more abundant in unlogged sites, where canopy foliage density and variability in the understory stratum were greatest. Multivariate analyses indicated that understory bat species composition differed strongly between logged and unlogged sites but provided little evidence of logging effects for the canopy fauna. Different responses among feeding guilds and taxonomic groups appeared to be related to foraging and echolocation strategies and to changes in canopy cover and understory foliage densities. Our results suggest that even low-intensity logging modifies habitat structure, leading to changes in bat species composition.     

Foraging behaviour and echolocation in the rufous horseshoe bat (Rhinolophus rouxi) of Sri Lanka

Summary In October 1984 foraging areas and foraging behaviour of the rufous horseshoe bat, Rhinolophus rouxi, were studied around a nursery colony on the hill slopes of Sri Lanka. The bats only foraged in dense forest and were not found in open woodlands (Fig. 1). This strongly supports the hypothesis that detection of fluttering prey is by pure tone echolocation within or close to echo-cluttering foliage. During a first activity period after sunset for about 30–60 min, the bats mainly caught insects on the wing. This was followed by a period of inactivity for another 60–120 min. Thereafter the bats resumed foraging throughout the night. They mainly alighted on specific twigs and foraged in flycatcher style. Individual bats maintained individual foraging areas of about 20x20 m. They stayed in this area throughout the night and returned to the same area on subsequent nights. Within this area the bats generally alighted on twigs at the same spots. Foraging areas were not defended against intruders. The bats echolocated throughout the night at an average repetition rate of 9.6±1.4 sounds/s. While hanging on twigs they scanned the surrounding area for flying prey by turning their bodies continuously around their legs. On average they performed one brief catching flight every 2 min and immediately returned to one of their favourite vantage points. Echolocation sounds may consist of up to three parts, a brief initial frequency-modulated (FM) component, a long constant frequency (CF) part lasting for about 40–50 ms, and a final FM part again (Fig. 4b, c). Adult males and females emitted pure tone frequencies in separate bands, the males from 73.5–77 kHz and the females from 76.5–79 kHz (Fig. 5). During scanning for prey from vantage points, the bats mostly emitted pure tones without any FM component (Fig. 4a). The last few pure tones emitted before take-off were prolonged to about 60 ms duration. The final FM part was therefore not an obligatory component of the echolocation signals in horseshoe bats. During flight and especially during emergence from the cave, most sounds consisted of a pure tone and loud initial and final FM sweeps. We therefore suggest that the initial FM part might also be relevant for echolocation. From our observations we conclude that the FM components are especially important during obstacle avoidance. In most sounds emitted in the field a fainter first harmonic was present. It was usually up to 30 dB fainter than the second harmonic, but in some instances it was as loud or even distinctly louder than the second one (Fig. 6a). Even within one sound the intensity relationship between the two harmonics may be reversed. We therefore suggest that the first harmonic is an integral part of the signal and relevant for information analysis in echolocation.     

Effects of Selective Logging on the Butterflies of a Bornean Rainforest

Abstract: Selective logging has been the main cause of disturbance to tropical forests in Southeast Asia, so the extent to which biodiversity is maintained in selectively logged forest is of prime conservation importance. We compared the butterfly assemblages of Bornean primary rainforest to those of rainforest selectively logged 6 years previously. We sampled by means of replicated transects stratified into riverine and ridge forests and we included roads in the logged forest. There was a three-fold variation in species richness and abundance over the 8-month sampling period. More species and individuals were observed in the logged forest, although between-replicate variability was high. Rarefied species richness was positively correlated with canopy openness within the range of disturbance levels encountered at our forest sites. Within families, there was no significant difference in the number of species between primary and logged forest. There was a significant difference in the relative abundance of species, but this was due largely to the abundance of one or two species. Community ordination separated the sites along a gradient of disturbance and revealed strong differences between riverine and ridge-forest butterfly assemblages in primary forest that were obscured in logged forest. There was no evidence that logging has resulted in a change in the composition of the butterfly assemblages from species with a local distribution to more widespread species. We conclude that at a logged forest site in close proximity to primary forest, low intensities of logging do not necessarily reduce the species richness or abundance of butterflies, although assemblage composition is changed.     

Chronic kidney diseases of uncertain etiology (CKDue) in Sri Lanka: geographic distribution and environmental implications

The increase in the number of chronic kidney disease (CKD) patients from the north central region of Sri Lanka has become a environmental health issue of national concern. Unlike in other countries where long-standing diabetes and hypertension are the leading causes of renal diseases, the majority of CKD patients from this part of Sri Lanka do not show any identifiable cause. As the disease is restricted to a remarkably specific geographical terrain, particularly in the north central dry zone of the country, multidisciplinary in-depth research studies are required to identify possible etiologies and risk factors. During this study, population screening in the prevalent region and outside the region, analysis of geoenvironmental and biochemical samples were carried out. Population screening that was carried out using a multistage sampling technique indicated that the point prevalence of CKD with uncertain etiology is about 2–3% among those above 18 years of age. Drinking water collected from high-prevalent and non-endemic regions was analyzed for their trace and ultratrace element contents, including the nephrotoxic heavy metals Cd and U using ICP-MS. The results indicate that the affected regions contain moderate to high levels of fluoride. The Cd contents in drinking water, rice from affected regions and urine from symptomatic and non-symptomatic patients were much lower indicating that Cd is not a contributing factor for CKD with uncertain etiology in Sri Lanka. Although no single geochemical parameter could be clearly and directly related to the CKD etiology on the basis of the elements determined during this study, it is very likely that the unique hydrogeochemistry of the drinking water is closely associated with the incidence of the disease.     

Distribution of Floristic Richness and Its Conservation in Sri Lanka

Abstract: The angiosperm flora of Sri Lanka, which has been comparatively well studied by many eminent botanists for over two centuries, has a rich endemic component and also exhibits strong affinities to that of peninsular India Some of the 15 floristic regions recognized in the island have exceptionally rich, highly localized floras. But increased forest disturbances over the years have taken a heavy toll. A plea is made to conserve at least one sufficiently large forest reserve in each floristic region. A meaningful conservation program has been launched in the Sinharaja MAB Reserve; similar programs are urgently needed for other protected areas of the island.     

Soil amendments and cultivar selection can improve rice yield in salt-influenced (tsunami-affected) paddy fields in Sri Lanka

The tsunami disaster in the Indian Ocean in December 2004 caused devastation of agricultural soils by salt water over wide areas. Many rice fields located close to the coast were affected by the flood of seawater. Electric conductivity (EC) of soils in tsunami-affected rice fields was found to be higher compared to unaffected fields 2 years after the tsunami. Four soil amendments (gypsum, dolomite, cinnamon ash and rice-husk-charcoal) were tested for their influence on improving the yield parameters of rice grown in a tsunami-affected and a non-affected area. Yield parameters were compared with an untreated control of the same cultivar (AT362) and with a salt resistant rice variety (AT354). The salt resistant variety had the highest grain yield. The two amendments gypsum and rice-husk-charcoal led to an increase in grain yield compared to the untreated control, whereas dolomite and cinnamon ash had no significant effect on grain yield.     

Floristic composition of sandy shore vegetation at Uswetakeiya in Sri Lanka

This study was conducted at Uswetakeiyawa on the southwestern part of Sri Lanka. Twenty-two families, 42 genera and 52 species were recorded from the sandy shore vegetation. Approximately 3.8 % (2 species) were found to be endemic and 67.3 % (35 species) were found to be of medicinal importance. Ipomea pes-capre and Spinifex littoreus were the most abundant species at the study site. The average value for all the zone combinations was β = 0.693, and the highest similarity value was ISj = 0.276, corresponding to two non-contiguous zones. The results show that a variation in plant diversity is to be found across the gradient. The typical zoning nature of the sandy shore vegetation has been disturbed due to on-going development in Uswetakeiyawa. New policy decisions should be taken to restrict development activities in Uswetakeiyawa in order to protect the sandy shore vegetation.     

Observations on metal concentrations in commercial landings of two species of tilapia (Oreochromis mossambicus and Oreochromis niloticus) from reservoirs in six river basins in Sri Lanka

Samples of the muscle of two species of tilapia (Oreochromis mossambicus and O. niloticus; 17–20 cm length) were obtained from at least one reservoir in each of the six river basins (Aruvi Aru, Kala Oya, Kirindi Oya, Ma Oya, Mahaweli, and Walawe Ganga catchments) in Sri Lanka. The metals Ca, Cu, Fe, K, Mg, Mn, Na, and Zn were consistently detected in the muscle tissue. Overall, there were few differences in the concentration of metals between the two species of fish, although there were also some statistically significant differences (p < 0.05) in the concentrations of some metals in fish obtained from some of the reservoirs. Aruvi Aru stands out as a river basin in which the two fish species have significantly lower concentration of metals when compared to other river basins. The concentration of the metals studied were below WHO and FSANZ guideline values for fish, suggesting that the consumption of the metals found in tilapia from these reservoirs poses little risk to human health.     

Geoenvironmental factors related to high incidence of human urinary calculi (kidney stones) in Central Highlands of Sri Lanka

An area with extremely high incidence of urinary calculi was investigated in the view of identifying the relationship between the disease prevalence and the drinking water geochemistry. The prevalence of the kidney stone disease in the selected Padiyapelella–Hanguranketa area in Central Highlands of Sri Lanka is significantly higher compared with neighboring regions. Drinking water samples were collected from water sources that used by clinically identified kidney stone patients and healthy people. A total of 83 samples were collected and analyzed for major anions and cations. The anions in the area varied in the order HCO₃ ^? > Cl^? > SO₄ ^2? > NO₃ ^? and cations varied in the order Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ > Fe²⁺. The dissolved silica that occurs as silicic acid (H₄SiO₄) in natural waters varied from 8.8 to 84 mg/L in prevalence samples, while it was between 9.7 and 65 mg/L for samples from non-prevalence locations. Hydrogeochemical data obtained from the two groups were compared using the Wilcoxon rank-sum test. It showed that pH, total hardness, Na⁺, Ca²⁺ and Fe²⁺ had significant difference (p < 0.005) between water sources used by patients and non-patients. Elemental ratio plots, Gibbs’ plot and factor analysis indicated that the chemical composition of water sources in this area is strongly influenced by rock–water interactions, particularly the weathering of carbonate and silicate minerals. This study reveals a kind of association between stone formation and drinking water geochemistry as evident by the high hardness/calcium contents in spring water used by patients.     

Effect of Experimental Selective Logging on Tropical Butterflies

Abstract: I investigated the effects of an experimental selective logging regime on the assemblage of fruit-feeding butterflies in replicated experimental plots in the Chiquibul Forest, Belize. Over a 12-month period, I caught 1187 individuals of 49 species using fruit-baited traps. Selective logging at densities of six stems per ha 3 years before the study had little effect on butterfly species richness, the abundance of individual species, or the shape of species-abundance distributions. There was no tendency for taxa with restricted geographical ranges to be particularly sensitive to selective logging. Mark-release-recapture results suggest that most butterflies move relatively short distances, but that some dispersal occurs between plots separated by distances of ≥1 km. The apparent similarity of the fruit-feeding butterfly assemblage in selectively logged and unlogged forest contrasts with previous studies of butterfly assemblages but mirrors results for birds in the same plots. A possible explanation is the high frequency of natural disturbance—hurricanes and associated fires—in the Chiquibul Forest. The species present appear to be adapted to naturally disturbed habitats and may therefore be relatively unaffected by selective logging. Local studies of the effects of selective logging must take into account the history of natural and human disturbance in the study area. The results support the case for "ecological forestry," in which sustainable management regimes work within the limits imposed by natural disturbance.     

Background levels of heavy metals in plants of different taxonomic groups from a montane rain forest in Sri Lanka

An undisturbed natural reserve area iocated in a tropical montane rain forest at about 1800 m altitude in Sri Lanka served as a study site to investigate and assess the natural background concentration levels of As, Cd, Co, Cu, Ni, Pb and Zn in plants representing different taxonomic groups (divisions) in the plant kingdom. The plants selected were: the lichen,Usnea barbata (old man's beard);Pogonatum sp. (a moss);Lycopodium selago (epiphytic lycopod);Polypodium lanceolatum (epiphytic fern);Bulbophyllum elliae (epiphytic orchid) andActinodaphne ambigua (dicotyledonous large tree). Degree of homogeneity with respect to Cd, Cu, Pb and Zn in homogenised materials of all samples were within acceptable limits, whereasPogonatum sp. showed the highest degree of homogeneity for Pb. In addition to confirming extremely low levels of heavy metals in all plant species, the survey also found that generally the primitive plants,Usnea andPogonatum appear to have a greater tendency to accumulate As, Cd, Co and Pb; in particular,U. barbata appears to be an efficient accumulator for those heavy metals, suggesting its potential use in environmental studies.Actinodaphne ambigua was found to have a specific accumulating ability for nickel. Surface cleaning of theA. ambigua leaves resulted in a substantial decrease in the foliar contents of Cd, Ni, Pb and Zn. Variations in heavy metal contents observed in different plant genera are discussed in terms of their habits and place of growth in the forest. It is anticipated that the background levels presented in this paper from a remote, unpolluted tropical ecosystem will provide useful reference data for comparative environmental studies.     

Inbreeding avoidance in a poeciliid fish (Heterandria formosa)

Polyandry is hypothesized to give females an opportunity to avoid inbreeding through postcopulatory selection mechanisms if precopulatory inbreeding avoidance is not possible, for example, because of forced matings. Here, we report a postcopulatory, prefertilization, inbreeding avoidance mechanism in the least killifish, Heterandria formosa, a species in which males can force matings. Females had 50% less sperm in their oviducts and ovarian cavities after mating with a sibling compared to a mating with a nonsibling male. Neither sex showed inbreeding avoidance in a dichotomous precopulatory mate choice test or during mating trials. Females in this species invest substantially in each offspring after fertilization (matrotrophy), whereas males invest little more than sperm. Based on theory, females should therefore be more likely than males to avoid inbreeding in this species. We suggest that females do this by reducing the amount of sibling sperm in their reproductive system. However, the possibility that males invested more sperm to nonsiblings could not be ruled out. In a fertilization success experiment, the first male to mate with a female sired all the offspring in most cases, even if it was a sibling. However, large females were more likely to carry offspring of multiple males. Possibly female sperm storage sites were filled by the first male, and only large females had space for the second male's sperm.     

Utilisation of mangroves and seagrasses by fishes in the Negombo Estuary,Sri Lanka

In two years of sampling, 10 287 fishes belonging to 62 species (39 families) were collected from mangroves and seagrasses of the Negombo Estuary. Of the species collected, 70% were marine, 27% estuarine and 3% freshwater. Aplocheilus melastigma, Ambassis dayi, Etroplus suratensis, E. maculatus, Bathygobius fuscus and Arothron immaculatus constituted 90% of the catch. Sixteen species were caught only from mangroves, 6 only from seagrasses, and 40 from both. The number of species, individuals, biomass and diversity were higher in seagrasses than in mangroves. Gobies and some siganids moved to the mangrove habitat as they grew, but cichlids, triacanthids, some eleotrids and tetraodontids preferred seagrasses. The number of species and individuals caught increased at the beginning of the north-east monsoon when the rainfall was low. The number of species and individual numbers were positively correlated with salinity and dissolved oxygen and negatively correlated with water temperature. Of the 33 species examined, seagrasses formed >25% of the gut content in juvenile Lates calcarifer, Apogon thermalis, E. suratensis, E. maculatus, Siganus javus, Butis butis and Bathygobius fuscus. Mangrove litter was the main gut content of the family Syngnathidae. E. suratensis, E. maculatus and S. javus from seagrasses contained more filamentous algae than seagrasses in their stomachs. S. javus collected from mangroves also contained more seagrasses in their stomachs than mangrove litter, indicating that the association of juvenile fishes with mangroves or seagrasses may not be obligate in estuaries subject to low tidal fluctuations.     

Pattern of distribution of selected trace elements in the marine brown alga,Sargassum filipendula Ag. from Sri Lanka

Baseline concentrations together with biological variations of 29 trace elements (Ag, As, Au, Ba, Br, Cd, Ce, Co, Cr, Cs, Eu, Fe, Hf, I, Mn, Mo, Ni, Pb, Rb, Sb, Sc, Se, Sm, Sr, Tb, Th, Yb, Zn and Zr) were investigated in the brown alga, Sargassum filipendula collected from the western coast of Sri Lanka. Several elements (Co, Cr, Fe, Hf, Ni, Sc, Se, Th, Zr and the rare earth elements) were found to be enriched in S. filipendula compared to NIES No. 9 Sargasso reference material. Concentration of strontium in S. filipendula was highest at all sites. Chemical abundance of the rare earth elements decreased approximately linearly with increasing atomic numbers. The pattern of elemental distribution appears to be due to the fact that S. filipendula seems capable of concentrating high levels of trace elements under conditions of their very low availability in sea water. Concentration factors for elements in S. filipendula lie in a higher range compared with those reported in the literaure for brown algae.     

Geochemical and mineralogical characteristics of elephant geophagic soils in Udawalawe National Park,Sri Lanka

Geophagy or deliberate ingestion of soils was observed among Asian elephants (Elephas maximus) in the Udawalwe National Park, Sri Lanka, for several years. The geochemical and mineralogical composition of the clayey soil layers which are purposefully selected and eaten by elephants in the park were studied, in order to identify the possible reasons for elephant geophagy. The concentrations of major and trace elements were determined by means of X-ray fluorescence spectrometry in 21 soil samples from eight geophagic sites and six soil samples collected from four non-geophagic sites. The mineralogical composition of selected soil samples was investigated using X-ray diffractometry (XRD). These geochemical analyses revealed that geophagic soils in the study areas are deeply weathered and that most of the elements are leached from the soil layers under extreme weathering conditions. The XRD data showed that the soils of the area consisted mainly quartz, feldspar, and the clay minerals kaolinite, Fe-rich illite, and smectite. Although no significant geochemical differences were identified between geophagic and non-geophagic soils, a clear difference was observed in their clay mineralogical content. Soils eaten by elephants are richer in kaolinite and illite than non-geophagic soils, which contain a higher amount of smectite. It is suggested that elephants in Udawalawe National Park ingest soils mainly not to supplement the mineral contents of their forage but to detoxify unpalatable compounds in their diet.     

Medical geology of endemic goiter in Kalutara,Sri Lanka; distribution and possible causes

This study assesses the distribution of goiter in the Kalutara District, Sri Lanka in order to find causative factors for the occurrence of goiter even after the salt iodization. A questionnaire survey was conducted at the household level and at the same time iodine and selenium levels of the water sources were analyzed. Questionnaire survey results indicated the highest numbers of goiter patients in the northern part where the lowest were found in the southern sector which may be due to the presence of acid sulfate soils. Females were more susceptible and it even showed a transmittance between generations. Average iodine concentrations in subsurface water of goiter endemic regions are 28.25 ± 15.47 μg/L whereas non-goiter regions show identical values at 24.74 ± 18.29 μg/L. Surface water exhibited relatively high values at 30.87 ± 16.13 μg/L. Endemic goiter was reported in some isolated patches where iodine and selenium concentrations low, latter was <10 μg/L. The formation of acid sulfate soils in the marshy lands in Kalutara district may lead to transformation of biological available iodine oxidation into volatile iodine by humic substances, at the same time organic matter rich peaty soil may have strong held of iodine and selenium which again induced by low pH and high temperature were suggested as the instrumental factors in the endemic goiter in Kalutara district. Hence, geochemical features such as soil pH, organic matter and thick lateritic cap in the Kalutara goiter endemic area play a role in controlling the available selenium and iodine for food chain through plant uptake and in water.