The influence of nutrient concentration on algal biomass and invertebrate communities in agricultural streams : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University, Palmerston North, New Zealand

High nutrient inputs have generally been identified as responsible for the degradation of lowland rivers and lakes in New Zealand and internationally. Nutrients have been shown to influence algal community growth rate and composition. In turn algae can have strong effects on invertebrate communities (density, richness, composition, distribution, structure and function). This study investigates the effect of nutrients on algal biomass and higher trophic levels to determine the importance of nutrient loading on stream ecosystems. Twenty six agricultural streams were surveyed in the Manawatu region in February, 2002. Algal biomass was greater in streams with high nitrate levels. Invertebrate communities differed in terms of the quantitative macroinvertebrate community index (QMCI), Ephcmeroptera, Plecoptera and Trichoptera (EPT) individuals and taxa between sites with high and low algal biomass. Regression analysis was used to relate the "quality" of the invertebrate community to stream algal biomass. At 13.μg/cm2 of chlorophyll a there was a dramatic shift in invertebrate community composition to more pollution tolerant taxa. In the Hawke's Ray region nutrient concentration was experimentally increased in 3 low order streams in the summer of 2002/2003. Increased nutrient concentration did not affect stream algal biomass. There were however changes in the proportions of EPT in the enriched community. I propose that these changes in EPT were in response to increased algal growth rates and constrained any increase in algal biomass. Therefore changes in landuse intensity may affect invertebrate community structure

A new substrate for sampling deep river macroinvertebrates

We compared macroinvertebrate communities colonising multiplate samplers constructed from perspex or tempered hardboard (wood) with an alternative artificial substrate constructed from folded coconut fibre matting (coir) enclosed in nylon netting. Substrates were incubated for 62 days over January to March 2007 at six sites over 240 km along the Waikato River. The three substrates supported similar numbers of invertebrate taxa (27 - 29 taxa), but coir samples contained 71% of total invertebrate numbers from all substrates combined, compared with <17% for each type of multiplate sampler. Coir faunas were heavily dominated by the hydrobiid snail Potamopyrgus (84 % of numbers), and this taxon along with the amphipod Paracalliope comprised 58 - 66 % of invertebrates on both types of multiplate samplers. Analysis of a Bray-Curtis matrix suggested statistically significant differences in percent community composition between coir samplers and each type of multiplate sampler over the late summer study period. Densities per cm3 of Oligochaeta, Mollusca, and "other worms" (Platyhelminthes, Rhabdocoela, Nemertea and Hirudinea combined) were significantly higher in coir samples than one or both of the multiplate samplers. Results suggest coir samplers may provide a useful supplement to multiplate samplers for deep river invertebrate studies by collecting a different range of taxa, including those favouring cover and characteristic of depositional environments

Television viewing time and risk of incident obesity and central obesity: the English longitudinal study of ageing

Background Research suggests television viewing time may be associated with incident obesity and central obesity in young adults. No study has investigated these associations in older English adults. The aim of this study was to investigate longitudinal associations between television viewing time and incident obesity and central obesity in a sample of older English adults. Analyses of data from the English Longitudinal Study of Ageing. At baseline (2008), participants reported their television viewing time. Research nurses recorded obesity and central obesity by body mass index and waist circumference, respectively, at four year follow-up. Associations between television viewing time and incident obesity (BMI > 30 kg/m2) and central obesity (waist >102 cm men; > 88 cm women) at four year follow-up were examined using adjusted logistic regression. Participants gave full written informed consent to participate in the study and ethical approval was obtained from the London Multicentre Research Ethics Committee. Results A total of 3777 initially non-obese participants (aged 64.8 ± 8.6 yrs, 46.4% male) were included in the analyses using BMI as an outcome and 2947 for the analyses using waist circumference. No significant associations were found between television viewing time and incident obesity. A significant association was found between watching ≥6 hrs/d of television (compared to <2 hrs/d) and central obesity (Odds Ratio 1.48; 95% confidence interval 1.07 to 2.03) after adjustment for covariables including physical activity. Conclusions In this sample of older community dwelling English adults greater television viewing time was associated with incident central obesity, but not total obesity when measured by BMI. Interventions to reduce the incidence of central obesity in this age group that focus on reducing TV time, as well as targeting other health behaviours (eg, increasing physical activity levels, improving dietary intake) might prove useful

Physical activity and cardiovascular mortality risk: possible protective mechanisms?

INTRODUCTION: The biological mechanisms through which increased physical activity or structured exercise training lowers the risk of recurrent cardiac events are incompletely understood. We examined the extent to which modification of primary risk markers explains the association between physical activity and cardiovascular death in participants with diagnosed cardiovascular disease (CVD). METHODS AND RESULTS: In a prospective study of 1429 participants with physician-diagnosed CVD living in England and Scotland (age = 66.5 ± 11.1 yr (mean ± SD), 54.2% men), we measured physical activity and several risk markers (body mass index, total-to-HDL cholesterol ratio, diagnosed diabetes, systolic blood pressure, resting heart rate, C-reactive protein) at baseline. The main outcome was CVD death. There were a total of 446 all-cause deaths during an average of 7.0 ± 3.1 yr of follow-up, of which 213 were attributed to cardiovascular causes. Participation in moderate to vigorous physical activity at least three sessions per week was associated with lower risk of CVD death (hazard ratio = 0.61, 95% confidence interval = 0.38-0.98). Physically active participants demonstrated significantly lower levels of body mass index, diabetes, and inflammatory risk (C-reactive protein). Metabolic (body mass index, total-to-HDL cholesterol ratio, and physician-diagnosed diabetes) and inflammatory risk factors explained an estimated 12.8% and 15.4%, respectively, of the association between physical activity and CVD death. CONCLUSIONS: Physical activity may reduce the risk of secondary CVD events, in part, by improving metabolic and inflammatory risk markers

Socioeconomic status as a risk factor for dementia death:individual participant meta-analysis of 86 508 men and women from the UK

Background Life-course socioeconomic factors may have a role in dementia aetiology but there is a current paucity of studies. Meta-analyses of individual participant data would considerably strengthen this evidence base. Aims To examine the association between socioeconomic status in early life and adulthood with later dementia death. Method Individual participant meta-analysis of 11 prospective cohort studies (1994-2004, n = 86 508). Results Leaving full-time education at an earlier age was associated with an increased risk of dementia death in women (fully adjusted hazard ratio (HR) for age ⩽14 v. age ⩾16: HR = 1.76, 95% CI 1.23-2.53) but not men. Occupational social class was not statistically significantly associated with dementia death in men or women. Conclusions Lower educational attainment in women was associated with an increased risk of dementia-related death independently of common risk behaviours and comorbidities

Non-exercise equations to estimate fitness in white European and South Asian men

Cardiorespiratory fitness is a strong, independent predictor of health, whether it is measured in an exercise test or estimated in an equation. The purpose of this study was to develop and validate equations to estimate fitness in middle-aged white European and South Asian men.Multiple linear regression models (n=168, including 83 white European and 85 South Asian men) were created using variables that are thought to be important in predicting fitness (VO2 max, mL⋅kg⋅min): age (years); BMI (kg·m); resting heart rate (beats⋅min); smoking status (0=never smoked, 1=ex or current smoker); physical activity expressed as quintiles (0=quintile 1, 1=quintile 2, 2=quintile 3, 3=quintile 4, 4=quintile 5), categories of moderate- to vigorous-intensity physical activity (0=&lt;75 min⋅wk, 1=75-150 min⋅wk, 2=&gt;150-225 min⋅wk, 3=&gt;225-300 min⋅wk, 4=&gt;300 min⋅wk), or minutes of moderate- to vigorous-intensity physical activity (min⋅wk); and, ethnicity (0=South Asian, 1=white). The leave-one-out-cross-validation procedure was used to assess the generalizability and the bootstrap and jackknife resampling techniques were used to estimate the variance and bias of the models.Around 70% of the variance in fitness was explained in models with an ethnicity variable, such as: VO2 max = 77.409 - (age*0.374) - (BMI*0.906) - (ex or current smoker*1.976) + (physical activity quintile coefficient) - (resting heart rate*0.066) + (white ethnicity*8.032), where physical activity quintile 1 is 1, 2 is 1.127, 3 is 1.869, 4 is 3.793, and 5 is 3.029. Only around 50% of the variance was explained in models without an ethnicity variable. All models with an ethnicity variable were generalizable and had low variance and bias.These data demonstrate the importance of incorporating ethnicity in non-exercise equations to estimate cardiorespiratory fitness in multi-ethnic populations

Introduction to stochastic error correction methods

We propose a method for eliminating the truncation error associated with any subspace diagonalization calculation. The new method, called stochastic error correction, uses Monte Carlo sampling to compute the contribution of the remaining basis vectors not included in the initial diagonalization. The method is part of a new approach to computational quantum physics which combines both diagonalization and Monte Carlo techniques.Comment: 11 pages, 1 figur

How does light intensity physical activity associate with adult cardiometabolic health and mortality? Systematic review with meta-analysis of experimental and observational studies

Aim To assess the relationship between time spent in light physical activity and cardiometabolic health and mortality in adults. Design Systematic review and meta-analysis. Data sources Searches in Medline, Embase, PsycInfo, CINAHL and three rounds of hand searches. Eligibility criteria for selecting studies Experimental (including acute mechanistic studies and physical activity intervention programme) and observational studies (excluding case and case-control studies) conducted in adults (aged >= 18 years) published in English before February 2018 and reporting on the relationship between light physical activity (<3 metabolic equivalents) and cardiometabolic health outcomes or all-cause mortality. Study appraisal and synthesis Study quality appraisal with QUALSYST tool and random effects inverse variance meta-analysis. Results Seventy-two studies were eligible including 27 experimental studies (and 45 observational studies). Mechanistic experimental studies showed that short but frequent bouts of light-intensity activity throughout the day reduced postprandial glucose (-17.5%; 95% CI -26.2 to -8.7) and insulin (-25.1%; 95% CI -31.8 to -18.3) levels compared with continuous sitting, but there was very limited evidence for it affecting other cardiometabolic markers. Three light physical activity programme intervention studies (n ranging from 12 to 58) reduced adiposity, improved blood pressure and lipidaemia; the programmes consisted of activity of > 150 min/week for at least 12 weeks. Six out of eight prospective observational studies that were entered in the meta-analysis reported that more time spent in daily light activity reduced risk of all-cause mortality (pooled HR 0.71; 95% CI 0.62 to 0.83). Conclusions Light-intensity physical activity could play a role in improving adult cardiometabolic health and reducing mortality risk. Frequent short bouts of light activity improve glycaemic control. Nevertheless, the modest volume of the prospective epidemiological evidence base and the moderate consistency between observational and laboratory evidence inhibits definitive conclusions

The combined association of psychological distress and socioeconomic status with all-cause mortality: a national cohort study.

BACKGROUND: Psychological distress and low socioeconomic status (SES) are recognized risk factors for mortality. The aim of this study was to test whether lower SES amplifies the effect of psychological distress on all-cause mortality. METHODS: We selected 66 518 participants from the Health Survey for England who were 35 years or older, free of cancer and cardiovascular disease at baseline, and living in private households in England from 1994 to 2004. Selection used stratified random sampling, and participants were linked prospectively to mortality records from the Office of National Statistics (mean follow-up, 8.2 years). Psychological distress was measured using the 12-item General Health Questionnaire, and SES was indexed by occupational class. RESULTS: The crude incidence rate of death was 14.49 (95% CI, 14.17-14.81) per 1000 person-years. After adjustment for age and sex, psychological distress and low SES category were associated with increased mortality rates. In a stratified analysis, the association of psychological distress with mortality differed with SES (likelihood ratio test-adjusted P < .001), with the strongest associations being observed in the lowest SES categories. CONCLUSIONS: The detrimental effect of psychological distress on mortality is amplified by low SES category. People in higher SES categories have lower mortality rates even when they report high levels of psychological distress