Culture-based fisheries in non-perennial reservoirs of Sri Lanka: influence of reservoir morphometry and stocking density on yield

Culture-based fish yield in non-perennial reservoirs of Sri Lanka was related to reservoir morphometry and stocking density. The reservoirs were stocked mainly with fingerlings of one Chinese and three Indian major carp species, common carp, Cyprinus carpio L., and the genetically improved farmed tilapia strain of Nile tilapia, Oreochromis niloticus (L.), at four pre-determined species combinations and a range of stocking densities [SD (fingerlings ha⁻¹)]. Twenty-three reservoirs were harvested successfully at the end of the culture period of 2002–2003. Basic limnological and morphometric parameters, including shoreline development (D_L) and shoreline area ratio (R_LA), were estimated for each of the 23 reservoirs. Bray–Curtis similarity and non-metric multidimensional scaling using mean values of limnological data revealed that reservoirs could be ordinated into two major clusters, one with intact sample distribution due to similar trophic characteristics and the other with scattered sample distribution. Reservoirs in the cluster with similar trophic characteristics showed significant correlation (P < 0.05) between R_LA and total fish yield (Y). A multiple regression equation, Y = −693 + 4810 R_LA + 0.484 SD, was generated to estimate fish harvest in relation to SD.

Area variation in recreational cycling in Melbourne : a compositional or contextual effect?

Objective: To examine whether compositional and/or contextual area characteristics are associated with area socioeconomic inequalities and between-area differences in recreational cycling.

Setting: The city of Melbourne, Australia.

Participants: 2349 men and women residing in 50 areas (58.7% response rate).

Main outcome measure: Cycling for recreational purposes (at least once a month vs never).

Design: In a cross-sectional survey participants reported their frequency of recreational cycling. Objective area characteristics were collected for their residential area by environmental audits or calculated with Geographic Information Systems software. Multilevel logistic regression models were performed to examine associations between recreational cycling, area socioeconomic level, compositional characteristics (age, sex, education, occupation) and area characteristics (design, safety, destinations or aesthetics).

Results: After adjustment for compositional characteristics, residents of deprived areas were less likely to cycle for recreation (OR 0.66; 95% CI 0.43 to 1.00), and significant between-area differences in recreational cycling were found (median odds ratio 1.48 (95% credibility interval 1.24 to 1.78). Aesthetic characteristics tended to be worse in deprived areas and were the only group of area characteristics that explained some of the area deprivation differences. Safety characteristics explained the largest proportion of between-area variation in recreational cycling.

Conclusion: Creating supportive environments with respect to safety and aesthetic area characteristics may decrease between-area differences and area deprivation inequalities in recreational cycling, respectively.

Heavy metal accumulation in soils at three field sites subject to effluent irrigation

Three field sites were chosen to study the environmental assimilative capacity of heavy metals in soil. These sites were the Werribee Farm and the Myome Farm in Australia and Shenyang Zhangshi Irrigation Area in China. The Werribee Farm and the Shenyang Zhangshi Irrigation Area received sewage treatment and application on land for a long time. The Myome farm is an experimental site in which investigations on land application of municipal wastewater on water repellent soils is currently being trailed. Heavy metal contamination, in particular Cr, Cu and Zn, in the Land Filtration soil of Werribee Farm was widespread. More than a century of sewage irrigation has occurred in the Werribee Farm. The temporal distribution pattern of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the soil at this site follow an exponential trend with time and the spatial distribution pattern of accumulation of heavy metals in different paddocks correlates with the number of years of sewage irrigation at that site in the Farm. Extensive sewage irrigation at Shenyang Zhangshi Irrigation Area resulted in significant Cd pollution in soil-plant (rice) system and poses a significant threat to the health of local people. Even after eight years since cessation of sewage irrigation, the bioavailable fractions of Cd in the soil as analyzed by sequential extraction techniques were very high thus illustrating long-term persistence. The simultaneous competitive adsorption of metals in water repellent soils (at Myome Farm in South Australia) was studied. In the competitive situation, Cr, Pb and Cu are the heavy metal cations more strongly adsorbed by the soil, whereas Cd, Ni and Zn are the least adsorbed. The increase in Freundlich adsorption capacity by clay amendment suggested that clayed soils are capable sorption of higher heavy metal loadings compared to the non-clayed water repellent soil, which is more vulnerable to heavy metal inputs. A simple model of environmental assimilative capacity is proposed. The results of comparison of the three field sites shows that the Werribee Farm has a higher environmental assimilative capacity of heavy metals in soil than the soils at Shenyang Zhangshi Irrigation Area and Myome Farm, however heavy metal contamination at Werribee Farm is still a concern. The model of environmental assimilative capacity of heavy metals in soil is an effective tool to assist management of effluent applied land irrigation systems and can be used to better design environmental engineering systems.

Assessment of spatiotemporal varying relationships between rainfall, land cover and surface water area using geographically weighted regression

Traditional regression techniques such as ordinary least squares (OLS) are often unable to accurately model spatially varying data and may ignore or hide local variations in model coefficients. A relatively new technique, geographically weighted regression (GWR) has been shown to greatly improve model performance compared to OLS in terms of higher R 2 and lower corrected Akaike information criterion (AICC). GWR models have the potential to improve reliabilities of the identified relationships by reducing spatial autocorrelations and by accounting for local variations and spatial non-stationarity between dependent and independent variables. In this study, GWR was used to examine the relationship between land cover, rainfall and surface water habitat in 149 sub-catchments in a predominately agricultural region covering 2.6 million ha in southeast Australia. The application of the GWR models revealed that the relationships between land cover, rainfall and surface water habitat display significant spatial non-stationarity. GWR showed improvements over analogous OLS models in terms of higher R 2 and lower AICC. The increased explanatory power of GWR was confirmed by the results of an approximate likelihood ratio test, which showed statistically significant improvements over analogous OLS models. The models suggest that the amount of surface water area in the landscape is related to anthropogenic drainage practices enhancing runoff to facilitate intensive agriculture and increased plantation forestry. However, with some key variables not present in our analysis, the strength of this relationship could not be qualified. GWR techniques have the potential to serve as a useful tool for environmental research and management across a broad range of scales for the investigation of spatially varying relationships.

In-situ cadmium phytoremediation using solanum nigrum L. : the bio-accumulation characteristics trail

In this study, Solanum nigrum L. was used in-situ for Cd phytoremediation in Cd polluted soil on Shenyang Zhangshi Irrigation area (SZIA) in 2008. The performance of the plant over the whole growth stage was assessed. Results showed, during the whole experimental stage, the aboveground biomass of single Solanum nigrum L. grew by a factor of 190, from 1.6 ± 0.4 g to 300.3 ± 30.2 g with 141.2 times extracted Cd increase from 0.025 ± 0.001 to 3.53 ± 0.16 mg. Both the distribution of biomass and amount of extracted Cd in the aboveground part of the plant changed according to the growth of the plant. Particularly, the percentage of biomass and extracted Cd in the stem increased from 20% to 80% and from 11% to 69%, respectively. The bioconcentration factor and transfer factor both varied significantly during the growth of the plant and the lowest values were measured at the flowering stage (0.94 ± 0.31 and 3.48 ± 1.14 respectively). The results in this paper provide reference values for the future research on the application of Solanum nigrum L. in phytoremediation and on chemical or/and agricultural strategies for phytoextraction efficiency enhancement.

Area-level socioeconomic status and incidence of abnormal glucose metabolism : the Australian diabetes, obesity and lifestyle (AusDiab) study

OBJECTIVE--To examine the role of area-level socioeconomic status (SES) on the development of abnormal glucose metabolism (AGM) using national, population-based data.

RESEARCH DESIGN AND METHODS--The Australian Diabetes, Obesity and Lifestyle (AusDiab) study is a national, population-based, longitudinal study of adults aged [greater than or equal to] 25 years. A sample of 4,572 people provided complete baseline (1999 to 2000) and 5-year follow-up (2004 to 2005) data relevant for these analyses. Incident AGM was assessed using fasting plasma glucose and 2-h plasma glucose from oral glucose tolerance tests, and demographic, socioeconomic, and behavioral data were collected by interview and questionnaire. Area SES was defined using the Index of Relative Socioeconomic Disadvantage. Generalized linear mixed models were used to examine the relationship between area SES and incident AGM, with adjustment for covariates and correction for cluster design effects.

RESULTS--Area SES predicted the development of AGM, after adjustment for age, sex, and individual SES. People living in areas with the most disadvantage were significantly more likely to develop AGM, compared with those living in the least deprived areas (odds ratio 1.53; 95% CI 1.07-2.18). Health behaviors (in particular, physical activity) and central adiposity appeared to partially mediate this relationship.

CONCLUSIONS--Our findings suggest that characteristics of the physical, social, and economic aspects of local areas influence diabetes risk. Future research should focus on identifying the aspects of local environment that are associated with diabetes risk and how they might be modified.

Conservation hotspots : implications of intense spatial area use by breeding male and female loggerheads at the Mediterranean’s largest rookery

The implementation of appropriate protection measures for endangered species in protected areas requires knowledge of their fine-scale habitat use. In May and June of 2006 and 2007, we used GPS loggers (some linked to the Argos system) and a conventional Argos transmitter to track male and female loggerhead turtles Caretta caretta in the vicinity of the breeding area of Laganas Bay within the National Marine Park of Zakynthos, Greece. We obtained (1) 9681 useable locations (mean: 1383 locations ind.–1; range: 519 to 2198 locations) from Tracktag GPS loggers attached to 7 females for a mean duration of 34 d (range: 17 to 52 d); (2) 1245 useable locations (mean: 311 locations ind.–1; range: 38 to 1110 locations) from 4 males fitted with Fastloc Argos tags for a mean duration of 29 d (range: 3 to 51 d) and (3) 100 locations from 1 male fitted with a conventional Argos satellite tag tracked for 128 d. GPS data indicated that before the onset of nesting, both males and females primarily used an area within 500 m of the shore along a core 9 km stretch of coastline, where existing protective legislation requires strengthening. Our observations suggest that a 76.7% female-biased operational sex ratio, measured previously from in-water surveys, may represent a realistic sex ratio estimate in the period before nesting starts. In the first month following the onset of nesting, female spatial distribution remained similar, whereas most males departed for distant areas presumably to forage. Our study provides quantitative evidence of the need to improve the management planning and conservation measures to protect sea turtles in a coastal breeding area, and new insights on male turtle migration.

Employing sea-level rise scenarios to strategically select sea turtle nesting habitat important for long-term management at a temperate breeding area

Management strategies to protect endangered species primarily focus on safeguarding habitats currently perceived as important (due to high-density use, rarity or contribution to the biological cycle), rather than sites of future ecological importance. This discrepancy is particularly relevant for species inhabiting beaches and coastal areas that may be lost due to sea-level rise over the next 100 years through climate change. Here, we modelled four sea-level rise (SLR) scenarios (0.2, 0.6, 0.9 and 1.3 m) to determine the future vulnerability and viability of nesting habitat (six distinct nesting beaches totalling about 6 km in length) at a key loggerhead sea turtle (Caretta caretta) rookery (Zakynthos, Greece) in the Mediterranean. For each of the six nesting beaches, we identified (1) the area of beach currently used by turtles, (2) the area of the beach anticipated to become inundated under each SLR, (3) the area of beach anticipated to become unsuitable for nesting under each SLR, (4) the potential for habitat loss under the examined SLR, and (5) the extent to which the beaches may shift in relation to natural (i.e. cliffs) and artificial (i.e. beach front development) physical barriers. Even under the most conservative 0.2 m SLR scenario, about 38% (range: 31–48%) total nesting beach area would be lost, while an average 13% (range: 7–17%) current nesting beach area would be lost. About 4 km length of nesting habitat (representing 85% of nesting activity) would be lost under the 0.9 m scenario, because cliffs prevent landward beach migration. In comparison, while the other 2 km of beach (representing 15% nests) is also at high risk, it has the capacity for landward migration, because of an adjoining sand-dune system. Therefore, managers should strengthen actions on this latter area, as a climatically critical safeguard for future sea turtle nesting activity, in parallel to regularly assessing and revising measures on the current high-use nesting habitats of this important Mediterranean loggerhead population.

Small area-level socioeconomic status and all-cause mortality within 10 years in a population-based cohort of women: Data from the Geelong Osteoporosis Study

Background: The social gradient of health and mortality is well-documented. However, data are scarce regarding whether differences in mortality are observed across socio-economic status (SES) measured at the small area-level. We investigated associations between area-level SES and all-cause mortality in Australian women aged ≥. 20. years. Methods: We examined SES, obesity, hypertension, lifestyle behaviors and all-cause mortality within 10. years post-baseline (1994), for 1494 randomly-selected women. Participants' residential addresses were matched to Australian Bureau of Statistics Census data to identify area-level SES, and deaths were ascertained from the Australian National Deaths Index. Logistic regression models were adjusted for age, and subsequent adjustments made for measures of weight status and lifestyle behaviors. Results: We observed 243 (16.3%) deaths within 10. years post-baseline. Females in SES quintiles 2-4 (less disadvantaged) had lower odds of mortality (0.49-0.59) compared to SES quintile 1 (most disadvantaged) under the best model, after adjusting for age, smoking status and low mobility. Conclusions: Compared to the lowest SES quintile (most disadvantaged), females in quintiles 2 to 5 (less disadvantaged) had significantly lower odds ratio of all-cause mortality within 10. years. Associations between extreme social disadvantage and mortality warrant further attention from research, public health and policy arenas.

Towards the optimization of performance of Atlantic salmon reared at different water temperatures via the manipulation of dietary ARA/EPA ratio

In recent years, aquaculture has been facing a series of new issues, including the necessary replacement of fish oil and fish meal because of their limited supply and sub-optimal water temperature conditions. Higher water temperatures are increasingly encountered as the result of climate change related phenomena and/or the practice of farming of species in areas with environmental characteristics outside their optimal physiological range, such as the case of Atlantic salmon (. Salmo salar) farming in Australia during the summer season. Previous studies in teleost fish have shown that when fish are exposed at higher environmental temperatures, fish had a preferential increased dietary intake for arachidonic acid (20:4n - 6, ARA). This observation suggests that, given the several metabolic roles of ARA, its dietary provision may play an important role in fish for adapting at sub-optimal high water temperatures. The objective of this study was therefore to evaluate the effects of different dietary ARA/EPA ratios in juvenile Atlantic salmon as affected by time of exposition to the diet and water temperatures, with particular focus to fish performance and possible resulting modifications of tissue fatty acid composition. The study showed that independently from dietary treatments, fish held at the higher temperatures had an increased ARA accumulation, primarily in the liver and this ARA accumulation increased over time. It was also shown that the combined dietary inclusion of ARA and EPA significantly improved fish performance, compared with diets either richer in ARA or EPA. A general trend toward higher content of n - 3 LC-PUFA at lower temperatures was also quite clear, especially in the liver. Therefore, and assuming that the trends in tissue fatty acid composition could be taken as a clue of the optimal fatty acid requirements of fish, the n - 6 requirement (and in particular ARA) clearly appears to be greater for Atlantic salmon raised at high water temperatures. Protein accumulation was higher in the diet with the combined dietary inclusion of ARA and EPA for fish held at high water temperature (20. °C), with a concomitant lipid reduction. This study shows the importance of dietary ARA for maximal growth in Atlantic salmon, particularly during the period of the year when high water temperatures are often encountered. Further studies specifically looking at optimal dietary ARA/EPA ratio and roles of ARA on myogenesis, stress physiology and immune status of cultured fish are warranted. Statement of relevance: Given the current high level of fish oil replacement in aquafeed, and the often encountered sub-optimal environmental temperatures, we believe that this study could be considered as timely and highly pertinent for the aquaculture industry and associated R&D sector.