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Introduction: The aim was to identify the association of iron status with educational performance and intelligence of adolescents., Method: This was a cross sectional comparative study among adolescents aged 13-15 years. Each iron deficient student was matched with an iron sufficient student from the same school, class and sex. Iron status was based on haemoglobin and serum ferritin levels. The marks for mathematics, science, Sinhala language and social science were considered to assess educational performance. Intelligence was measured by Raven's Standard progressive matrices. All the possible confounders and effect modifiers were considered. Home visits to a sub-sample checked the quality of data., Results: The final analysis included 188 students (94 matched pairs). Neither educational performance nor intelligence showed significant associations with the iron status. The severity of the iron deficiency did not relate to these cognitive variables either. Twenty-three and 8 co-variables showed statistically significant associations with educational performance and intelligence respectively. Following a multiple regression analysis intelligence, the enthusiasm of the student towards learning, occupational ambition, household possession, problems at home and private tuition for mathematics were key factors predicting educational performance. Stunting and educational level of the mother were important factors influencing intelligence., Conclusion: Iron status does not play a major role in educational performance and intelligence of school going adolescents. Several factors affect educational performance and intelligence. This study highlights the difficulty in extrapolating the findings of similar studies to different ecological settings.

Hydra hexactinella was used to assess the toxicity of stormwater and sediment samples from three retarding basins in Melbourne, Australia, using an acute test, a sublethal test, and a pulse test. Stormwater from the Avoca St retarding basins resulted in a LC50 of 613 ml/L, NOEC and LOEC values of 50 ml/L and 100 ml/L, while the 7h pulse exposure caused a significant increase in the mean population growth rate compared to the control. Water samples from the two other retarding basins were found non-toxic to H. hexactinella. This is the first study to employ sediment tests with Hydra spp. on stormwater sediments and a lower population growth rate was observed for organisms exposed to sediment from the Avoca St retarding basins. The behavioral study showed that H. hexactinella tended to avoid the sediment-water interface when exposed to sediment from all retarding basins, compared to the reference sediment. Further work is needed to determine the long-term effects of stormwater polluted sediments and acute effects due to organism exposure to short-term high concentrations during rain events.

Vitellogenin (Vtg) is a yolk protein precursor that has been identified as a sensitive biomarker for exposure to estrogenic compounds. We evaluated specific monoclonal and polyclonal antibodies for reactivity with plasma Vtg from two Australian Perciformes, the tropical barramundi (Lates calcarifer) and the temperate black bream (Acanthopagrus butcheri). Blood plasma from 17beta-estradiol exposed (E2) male barramundi (20 mg kg(-1)) and male black bream (2.5-5.0 mg kg(-1)) were sent to Biosense Laboratories (Norway) for cross-reactivity testing using their extensive anti-Vtg antibody selection. Indirect ELISA results determined barramundi plasma displayed the highest binding affinities to ND-3G2 (monoclonal-Mab) and PO-1 (polyclonal-Pab). Black bream was most cross-reactive with ND-1C8 (Mab) and PO-2 (Pab). Next, plasma was assessed for Vtg induction in E2-dosed (5 mg kg(-1)), hatchery-reared barramundi and black bream versus a non-injected control group. Vtg production was assessed by Western blot and indirect ELISA using ND-3G2 and ND-1C8 Mabs, respectively. A prominent band was identified in the range of 100-200 kDa for all female black bream and for all E2-treated barramundi and black bream males, which was confirmed as Vtg by Western blot. Indirect ELISA results for barramundi demonstrated highly significant differences in E2-dosed fish as compared to control fish (Student t, P<0.001). E2 male black bream were significantly different than control males (Student t, P<0.001) and control and E2 females displayed highly significant differences (Student t, P<0.001). These results indicate that exposure to 17beta-estradiol induces significant Vtg production in males of the two Australian Perciformes, with potential use as a biomarker for exposure to estrogenic compounds.

Hormesis and essentiality are likely real and common effects at the level of the individual. However, the widespread incorporation of stimulatory effects into applications of ecotoxicology requires the acceptance of assumptions, value judgements and possibly lowering of water/sediment quality standards. There is also currently little data appropriate for considering hormetic effects in the ecotoxicological context. Except perhaps in the case of fitting concentration-response curves, it is not clear that incorporation of hormetic and essentiality type responses into ecotoxicology is necessary. Furthermore, its incorporation presents considerable intellectual and practical changes for ecotoxicology and could have unanticipated consequences.

Coastal environments are threatened by the increasing frequency, extent and severity of hypoxic events. Hypoxia affects vast areas around the world and often causes fish kills, reduced abundance, altered distribution, low benthic biomass and declines in fisheries. In Australia, many fisheries are based on sparid fishes and in the southern states black bream (Acanthopagrus butcheri) is important to both the recreational and commercial sectors. This species completes its entire life cycle in estuaries and annual recruitment is highly variable and very likely influenced by environmental conditions during the spawning season. In a laboratory-based experiment, fertilised black bream eggs (embryos) were exposed to five different levels of dissolved oxygen (DO). The DO levels were maintained in small test wells using nitrogen gas in a novel chamber design. Embryo development was assessed over a 2-day period and hatched larvae were observed until Day 2 post-hatch. Significant differences (p<0.05) were observed in embryonic development and survival as a function of DO level. In severely hypoxic conditions (30% saturation) survival to 1 day was reduced and no hatching occurred. In moderately hypoxic conditions (45-55%S), both precocious and delayed hatching was observed and hatch rates were reduced, whilst the number of hatched larvae with deformities increased, resulting in reduced larval lengths. No larvae survived to Day 2 post-hatch when held in hypoxic conditions (<55%S). This study demonstrates the detrimental effect that severe hypoxia can have on the early development of black bream which could result in reduced recruitment and lowered abundance. Other species that share similar early life histories may also be at risk.

Juvenile Cherax destructor was investigated as a potential test species for toxicity testing of trace metals in Australian freshwater systems. Adult male and female C. destructor were bred in the laboratory to obtain 4-week old juveniles, which were used in the toxicity tests. Animals were exposed to a range of concentrations of the trace metals ions copper (377-1275 microg/L), cadmium (377-1275 microg/L), nickel (300-1013 mg/L) and iron (36-168 mg/L) in static-renewal 96-h bioassays. The 96-h LC50 value for cadmium was 379, 494 microg/L for copper, 50 mg/L for iron and 327 mg/L for nickel demonstrating a decreasing toxicity of these metals to C. destructor. Comparison of LC50 values for metals for this species with those for other aquatic organisms reveals that C. destructor is less sensitive to trace metals than most other tested species.

Increased salinity in rivers and streams is a serious environmental concern, and in Australia there is growing information about the acute tolerances to salinity for freshwater macroinvertebrates, but much less information about chronic and sub-lethal tolerances. The effects of increased salinity on the growth and survival of two mayflies, Cloeon sp. and Centroptilum sp. and one midge Chironomus sp. are reported. In both mayfly species survival was variable. Complete mortality was observed in salinities with electrical conductivity of 10 mS cm(-1) and higher. Salinities causing chronic mortality in mayflies were measured as 21-day LC50, and ranged from 0.90 to 2.7 mS cm(-1). Growth rates were not significantly different between treatments. In Chironomus, salinity affected the mean number emerging as flying adults as well as the time to emergence. An inverted 'U' shape response was observed for percentage emergence, with the greatest numbers emerging at intermediate salinities (0.65-5.0 mS cm(-1)). No emergence occurred at salinities of 20 mS cm(-1) and higher. Time to emergence was delayed by 15-88% with increased salinity, however the size of emerged adults was the same for all treatments. Growth rates were reduced with increased salinity, showing a slow, steady reduction up to 10 mS cm(-1) then a steep decline between 10 and 15 mS cm(-1). The implications of altered growth rates and changes in developmental times are discussed. This study illustrates the variability in responses to increased salinity, and highlights the need to continue studying sub-lethal and chronic exposures in a range of freshwater invertebrates, in order to predict impacts of salinisation on freshwater biodiversity.

Effects of sublethal concentrations of chlorpyrifos (ranging from 0.005 (0.01 LC(50)) to 0.500 microg/L (1 LC(50))) on population characteristics of individual cultures of Daphnia carinata were investigated over 21 days with subsequent testing of the two next generations. The endpoints for the first and second generations observed were survival, fecundity, time to first brood, and number of offspring per female. The results were incorporated into the computation of the intrinsic rate of natural increase for daphnids in each of the treatments. Exposure to chlorpyrifos affected survival and fecundity of animals in the first generation. In the second generation, the most affected endpoint was time to the first brood with an indication of hormesis. The LC(50) tests were then conducted using animals of the third generation from each of the exposures in individual tests. Despite the absence of a negative effect of chlorpyrifos in the second generation, results of testing the third generation showed constant significant decline in LC(50) from control daphnids through to 0.1 LC(50) preexposed daphnids (0.1 LC(50), 0.05 microg/L, being the highest concentration in which animals survived exposure to the toxicant in the second generation).

Increasing salinity has the potential to affect freshwater organisms. Yet sub-lethal effects of salinity on macroinvertebrates are poorly understood. Growth and development of Ischnura heterosticta (Odonata: Coenagrionidae) was experimentally shown to be faster in 5-20 mS/cm than 0.1-1 mS/cm, while in 35 mS/cm all individuals died. In 30 mS/cm about half died and growth was similar to the 0.1 mS/cm treatment. The salinity-growth relationship cannot be explained indirectly, that is salinity affecting the survival of their prey. Tissue content and concentration of Ca, Mg, Na and K in emerged adults showed no evidence of deficiencies at low salinity. Heart beat rate was similar across treatments, except at 35 mS/cm, where it was slower. Respiration and feeding were similar at 0.1, 10 and 30 mS/cm. While there are similarities in I. heterosticta and other species' salinity response, there are differences and studies on more species are urgently needed.

The availability of literature regarding sublethal and chronic toxicity of heavy metals to early life stages of marine species is restricted to a few species of invertebrate mollusks. The early life stage of abalone, an important gastropod both environmentally and commercially, has been involved in limited research investigating the effects of heavy metal toxicity. Fertilized eggs of Haliotis rubra were exposed to a range of dissolved nominal concentrations of cadmium, copper, iron, lead, mercury, and zinc in individual solutions for 48 h. After 48 h of exposure, the test was completed by recording survival success and morphological abnormalities of veliger larvae in each heavy metal treatment. The mean 48-h median effective concentrations affecting normal morphological development of veliger larvae determined in this test shows a decreasing order of toxicity of copper (7 mg/L), mercury (21 mg/L), zinc (35 mg/L), iron (4102 mg/L), cadmium (4515 mg/L), and lead (5111 mg/L).

The growth and reproduction of the freshwater snail Physa acuta (Gastropoda: Physidae) were measured at various salinity levels (growth: distilled water, 50, 100, 500, 1000 and 5000 microS/cm; reproduction: deionized water, 100, 500, 1000 and 3000 microS/cm) established using the artificial sea salt, Ocean Nature. This was done to examine the assumption that there is no direct effect of salinity on freshwater animals until a threshold, beyond which sub-lethal effects, such as reduction in growth and reproduction, will occur. Growth of P. acuta was maximal in terms of live and dry mass at salinity levels 500-1000 microS/cm. The number of eggs produced per snail per day was maximal between 100 and 1000 microS/cm. Results show that rather than a threshold response to salinity, small rises in salinity (from low levels) can produce increased growth and reproduction until a maximum is reached. Beyond this salinity, further increases result in a decrease in growth and reproduction. Studies on the growth of freshwater invertebrates and fish have generally shown a similar lack of a threshold response. The implications for assessing the effects of salinisation on freshwater organisms need to be further considered.

Nodularia spumigena periodically proliferates to cause toxic algal blooms with some aquatic animals enduring and consuming high densities of the blue green algae or toxic lysis. N. spumigena contains toxic compounds such as nodularin and lipopolysaccharides. This current work investigates physiological effects of exposure from bloom conditions of N. spumigena cells and a post-bloom lysis. Biochemical and antioxidative biomarkers were comparatively studied over an acute 3-day exposure. In general, a post-bloom N. spumigena lysis caused opposite physiological responses to bloom densities of N. spumigena. Specifically, increases in glutathione (GSH) and glutathione peroxidase (GPx) and decreases in glutathione S-transferase (GST) were observed from the N. spumigena lysis. In contrast, N. spumigena cell densities decreased GSH and increased GST and lipid peroxidation (LPO) in mussels. Findings also suggest that at different stages of a toxic bloom, exposure may result in toxic stress to specific organs in the mussel.

The degree to which laboratory derived measures of salinity tolerance reflect the field distributions of freshwater biota is uncertain. In this paper we compare laboratory-derived acute salinity tolerance (LC(50) values) of freshwater macroinvertebrates (range 5.5-76 mS/cm) and fish (range 2.7-82 mS/cm) from southeastern Australia with the salinity from which they have been collected in the field. Only 4% of the macroinvertebrates were collected at salinity levels substantially higher than their 72-h LC(50) obtained from directly transferring animals from low salinity water to the water they were tested (direct transfer LC(50)). This LC(50) value was correlated with the maximum salinity at which a species had been collected. For common macroinvertebrates, the maximum field salinity was approximated by the direct transfer 72-h LC(50). For adult freshwater fish, 21% of species were collected at salinities substantially greater than their acute direct transfer LC(50) and there was a weak relationship between these two variables. Although there was a weak correlation between the direct transfer LC(50) of early life stages of freshwater fish and the maximum field salinity, 58% of the field distribution were in higher than their LC(50) values. In contrast, LC(50) determined from experiments that acclimated adult fish to higher salinity (slow acclimation) provided a better indication of the field distribution: with only one fish species (7%) being in conflict with their maximum field salinity and a strong positive relationship between these variables. This study shows that laboratory measures of acute salinity tolerance can reflect the maximum salinity that macroinvertebrate and fish species inhabit and are consistent with some anecdotal observations from other studies.

To assess the impacts of two oil spill remediation techniques on fish metabolism, change in aerobic and anaerobic enzyme activities in juvenile Australian Bass, Macquaria novemaculeata, was examined. Changes in cytochrome C oxidase (CCO) and lactate dehydrogenase (LDH) activities were investigated following exposure to the crude oil water accommodated fraction (WAF) and chemically dispersed crude oil WAF. There was a significant stimulation in CCO activity in the gills and livers of fish exposed to the WAF of Bass Strait crude oil and chemically dispersed crude oil, compared to the control treatment. In addition, LDH activity was significantly stimulated in the liver of fish exposed to dispersed crude oil WAF, compared to the crude oil WAF. Fish exposed to the dispersed crude oil WAF treatment had significantly higher oxygen consumption, as measured by oxygen depletion in a sealed chamber, than fish exposed to the crude oil WAF and control treatments., (Copyright 2001 Academic Press.)

Although Sri Lanka has generally a young demographic profile, with decreasing overall mortality and birth rates, its population is aging gradually and will continue to do so in the future. In order to have an idea of the needs of the elderly a survey was conducted in a sample of randomly selected Sinhalese elders living in an urban community. Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL) assessments were done. Ten percent of the respondents had at least one ADL impairment. Another ten percent had only IADL impairment. The commonest ADL to be affected were bathing and feeding. Children and the family provide all care for the impaired elderly. The family support system should be encouraged and assisted to prevent the necessity for more formal and expensive institutional care. A large proportion of the elderly were handicapped with defects in vision and hearing and the absence of teeth. Correction of these defects would improve both quality of life of these subjects and reduce their risk of accidents.

The prevalence of diabetes mellitus and impaired glucose tolerance (IGT) in a rural Sri Lankan community adopting the World Health Organization (WHO) criteria were 2.5% and 8% respectively. The low socioeconomic status, adequate physical exercise and the low prevalence of obesity appear to have not only contributed to the low prevalence of diabetes but also has prevented progression from IGT to overt diabetes.

The health status of an urban elderly Sinhala population ordinarily resident in their homes was investigated by interview and physical examination. Just over one fifth of the subjects had been hospitalised at least once for an episode of illness during the previous 12 months. 47.7% of the subjects complained of impaired vision, and 12.8% had cataract; 45.0% had less than the minimum number of teeth required for proper mastication; 24.8% of the subjects had impaired hearing. Medical histories showed that 10.1% of the subjects suffered from haemorrhoids; 2.0% were hemiplegic. A random single blood pressure recording showed 34.2% of the subjects to have a diastolic blood pressure of 95 mm Hg or more. 9.4% of the subjects had glucosuria. With the high morbidity seen among this elderly population a case is made for the establishment of geriatric clinics in government hospitals, and that care of the elderly be included in the Primary Health Care programme of Sri Lanka.