39 research outputs found

    Factors influencing the downstream transport of sediment in the Lough Feeagh catchment, Burrishoole, Co. Mayo, Ireland

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    Research laboratories in the Burrishoole catchment have been the focus of salmonid research since 1955. One aspect of the research has been to monitor the number of salmon and sea trout migrating to sea as smolts and returning to the catchment as adults. In the early 1990s it became clear that the smolt output from the catchment had declined over the previous two decades. At about the same time the presence of fine particles of peat silt in the hatchery became increasingly apparent and led to a higher incidence of mortality of young fry. These observations and management difficulties led to a study of silt transport in the surface waters of the catchment, which is described in this article. The authors describe geology, soils, climate and hydrology of Burrishoole before examining the sediment deposition in Lough Feeagh

    The EC Water Framework Directive and monitoring lakes in the Republic of Ireland

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    The authors of the article explore and discuss the effects of implementing the EC Water Framework Directive (WFD) in the Republic of Ireland. They also summarise some of the findings from a survey of 31 lakes sampled regularly between March 1996 and December 1997. The lakes were sampled regularly for a range of physico-chemical and biotic variables that probably would be important for monitoring programmes implemented under the WFD. The authors discuss problems of monitoring lake types with varying seasonal patterns

    Impact of naturally spawning captive-bred Atlantic salmon on wild populations: depressed recruitment and increased risk of climate-mediated extinction

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    The assessment report of the 4th International Panel on Climate Change confirms that global warming is strongly affecting biological systems and that 20–30% of species risk extinction from projected future increases in temperature. It is essential that any measures taken to conserve individual species and their constituent populations against climate-mediated declines are appropriate. The release of captive bred animals to augment wild populations is a widespread management strategy for many species but has proven controversial. Using a regression model based on a 37-year study of wild and sea ranched Atlantic salmon (Salmo salar) spawning together in the wild, we show that the escape of captive bred animals into the wild can substantially depress recruitment and more specifically disrupt the capacity of natural populations to adapt to higher winter water temperatures associated with climate variability. We speculate the mechanisms underlying this seasonal response and suggest that an explanation based on bio-energetic processes with physiological responses synchronized by photoperiod is plausible. Furthermore, we predict, by running the model forward using projected future climate scenarios, that these cultured fish substantially increase the risk of extinction for the studied population within 20 generations. In contrast, we show that positive outcomes to climate change are possible if captive bred animals are prevented from breeding in the wild. Rather than imposing an additional genetic load on wild populations by releasing maladapted captive bred animals, we propose that conservation efforts should focus on optimizing conditions for adaptation to occur by reducing exploitation and protecting critical habitats. Our findings are likely to hold true for most poikilothermic species where captive breeding programmes are used in population management

    Which method is best for the induction of labour?: A systematic review, network meta-analysis and cost-effectiveness analysis

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    Background: More than 150,000 pregnant women in England and Wales have their labour induced each year. Multiple pharmacological, mechanical and complementary methods are available to induce labour. Objective: To assess the relative effectiveness, safety and cost-effectiveness of labour induction methods and, data permitting, effects in different clinical subgroups. Methods: We carried out a systematic review using Cochrane methods. The Cochrane Pregnancy and Childbirth Group’s Trials Register was searched (March 2014). This contains over 22,000 reports of controlled trials (published from 1923 onwards) retrieved from weekly searches of OVID MEDLINE (1966 to current); Cochrane Central Register of Controlled Trials (The Cochrane Library); EMBASE (1982 to current); Cumulative Index to Nursing and Allied Health Literature (1984 to current); ClinicalTrials.gov; the World Health Organization International Clinical Trials Registry Portal; and hand-searching of relevant conference proceedings and journals. We included randomised controlled trials examining interventions to induce labour compared with placebo, no treatment or other interventions in women eligible for third-trimester induction. We included outcomes relating to efficacy, safety and acceptability to women. In addition, for the economic analysis we searched the Database of Abstracts of Reviews of Effects, and Economic Evaluations Databases, NHS Economic Evaluation Database and the Health Technology Assessment database. We carried out a network meta-analysis (NMA) using all of the available evidence, both direct and indirect, to produce estimates of the relative effects of each treatment compared with others in a network. We developed a de novo decision tree model to estimate the cost-effectiveness of various methods. The costs included were the intervention and other hospital costs incurred (price year 2012–13). We reviewed the literature to identify preference-based utilities for the health-related outcomes in the model. We calculated incremental cost-effectiveness ratios, expected costs, utilities and net benefit. We represent uncertainty in the optimal intervention using cost-effectiveness acceptability curves. Results: We identified 1190 studies; 611 were eligible for inclusion. The interventions most likely to achieve vaginal delivery (VD) within 24 hours were intravenous oxytocin with amniotomy [posterior rank 2; 95% credible intervals (CrIs) 1 to 9] and higher-dose (≥ 50 μg) vaginal misoprostol (rank 3; 95% CrI 1 to 6). Compared with placebo, several treatments reduced the odds of caesarean section, but we observed considerable uncertainty in treatment rankings. For uterine hyperstimulation, double-balloon catheter had the highest probability of being among the best three treatments, whereas vaginal misoprostol (≥ 50 μg) was most likely to increase the odds of excessive uterine activity. For other safety outcomes there were insufficient data or there was too much uncertainty to identify which treatments performed ‘best’. Few studies collected information on women’s views. Owing to incomplete reporting of the VD within 24 hours outcome, the cost-effectiveness analysis could compare only 20 interventions. The analysis suggested that most interventions have similar utility and differ mainly in cost. With a caveat of considerable uncertainty, titrated (low-dose) misoprostol solution and buccal/sublingual misoprostol had the highest likelihood of being cost-effective. Limitations: There was considerable uncertainty in findings and there were insufficient data for some planned subgroup analyses. Conclusions: Overall, misoprostol and oxytocin with amniotomy (for women with favourable cervix) is more successful than other agents in achieving VD within 24 hours. The ranking according to safety of different methods was less clear. The cost-effectiveness analysis suggested that titrated (low-dose) oral misoprostol solution resulted in the highest utility, whereas buccal/sublingual misoprostol had the lowest cost. There was a high degree of uncertainty as to the most cost-effective intervention

    The position of the Gulf Stream and lake nitrate concentrations in southwest Ireland

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    A positive relationship was observed between winter nitrate concentrations in two lakes in SW Ireland and the latitudinal position of the Gulf Stream position in the previous spring. Weaker but statistically significant relationships were apparent between the Gulf Stream position and weather variables, as well as soil moisture levels, in the same year. Wind speed, cloud cover and precipitation in May and June were negatively related to the Gulf Stream position in April. In contrast, air temperature and sunshine hours in May and June and the magnitude of the soil moisture deficit in June were positively related. There was also a positive correlation between the magnitude of the early summer soil moisture deficit and lake nitrate concentrations in the following winter. This three way linkage implies that the concentration of winter nitrate in these lakes is influenced by a sequence of related factors that are initiated by the latitudinal position of the Gulf Stream. In this sequence the position of the Gulf Stream appears to influence early summer weather in SW Ireland which in turn dictates the extent of moisture deficit in catchment soils and, consequently, the degree of nitrate loss to surface waters in the autumn. This connection, between events in the Atlantic Ocean, weather systems in the North West Atlantic and processes in catchment soils in SW Ireland has implications for both the quality and quantity of biota in lakes and catchments in the region

    The impact of climate change on lakes in Britain and Ireland

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    The North Atlantic Oscillation: implications for freshwater systems in Ireland.

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    The North Atlantic Oscillation is a winter phenomenon in which the north-south contrast in barometric pressure in the Atlantic shows interannual variability with approximately decadal cycles. Positive NAO index values are associated with increased wind speeds, temperatures and rainfall in Northern Europe. The present study explored the possible impacts of the NAO in the west of Ireland. Data was obtained from two synoptic meteorological stations (Valentia, Co. Kerry and Belmullet, Co. Mayo) and two lake systems (Lough Leane, Co. Kerry and Lough Feeagh, Co. Mayo). Mean winter air temperature, wind speed, rainfall, relative humidity and cloud amount were all found to be positively related to the NAO. In contrast, the relationship between solar radiation and the NAO was negative. Interannual variation in surface water temperatures and soil temperatures was also found to be highly dependent on the NAO. An inverse relationship was found between winter chlorophyll in Lough Leane and the NAO. The processes that might link winter phytoplankton biomass to the NAO were not confirmed. However, the results establish that the signal of the NAO is discernable in lacustrine biological activity in the west of Ireland

    Impacts of climate change on phosphorus loading from a grassland catchment – implications for future management

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    Dynamic modelling was used to quantify the impact of projected climate change, and potential changes in population and land-use, on phosphorus (P) export from a sub-catchment in SW Ireland using the Generalised Watershed Loading Functions (GWLF) model. Overall the results indicated that the increase in annual TP loads attributable to climate change was greater than that from either population or land-use change, and therefore that future climate variability will pose an increasingly significant threat to the successful long-term implementation of catchment management initiatives. The seasonal pattern in projected P export mirrored changes in streamflow, with higher rates between January and April and lower rates in summer. The potential reduction in export in summer was, however, negated when increases in population were included in simulations. A change in the slurry spreading period from that stipulated in national regulations to the months between April and September could potentially mitigate against future increases in dissolved P export in spring. The results indicate that projected changes in climate should be included when undertaking modelling exercises in support of decision making for catchment management plans
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