Within- and among-individual variation in metabolic rate in juvenile Atlantic salmon, Salmo salar

Animals may adopt a range of energy strategies to persist and perhaps prosper under various prevailing environmental conditions. For example, they may achieve similar growth by investing heavily in maintaining a high capacity food capture and processing system or by using a lower capacity system that is cheap to run but which is less effective at accruing further resources. The way that individuals within species allocate energy resources is an intriguing issue that has implications for understanding competition, population structuring and the response of populations to environmental change. Energy budgets account quantitatively for the pathways by which food energy results in variation in somatic resources and constitute an important basis for evaluating links between behaviour and aspects of performance. Atlantic salmon have been an important model for exploring relationships between growth performance, metabolic strategies and individual behaviour. Juvenile salmonid fish have been a particularly useful subject for exploring individual variation in metabolism because it has been possible to relate standard metabolic rate (SMR) to behavioural traits and lifestyle within a species. SMR correlates with dominance status, which is reflected in the ability of fish to access high value food patches and may promote faster growth under some conditions. This thesis focuses on the within- and among-individual variation in SMR and looks at how a fish’s external environment and social interactions can influence its SMR, and whether this variation in SMR can affect other aspects of metabolism such as feeding. Experiments were carried out to determine: (A) whether the presence of a shelter reduces SMR; this may provide an additional reason for the extent to which these fish will compete aggressively for shelters when these are limiting (Chapter 2); (B) the extent of intraspecific variation in SDA (i.e. differences in the measured parameters that are used to define SDA), and to test whether the SDA for a given meal varies as a function of individual traits such as SMR. If SMR is directly related to scope for growth, then the speed and size of the SDA response should also correlate with SMR (Chapter 3); (C) whether ventilation rate is sufficiently accurately related to metabolic rate (MR) at a range of temperatures and activities so as to allow energy expenditure to be predicted outside a respirometer (Chapter 4); and (D) how visual isolation and the presence of a conspecific can affect SMR, using the method developed in the previous chapter (Chapter 5). Access to shelter was shown to have a significant impact on SMR, producing on average a 30% increase in metabolic costs in the absence of shelter. Therefore, the presence of appropriate shelter not only reduces the risk of predation but also provides a metabolic benefit to fish that is likely to have implications for growth performance and activity budgets. Variation in SMR was shown to affect the profile of energy consumption during digestion of a meal. The peak in post-prandial oxygen consumption, the duration of elevated metabolism and the overall magnitude of SDA all increased with the size of meal consumed. However, for a given meal size, fish with a higher SMR also had a higher peak and greater magnitude of SDA, yet experienced a shorter duration over which metabolism was elevated following the meal. Intraspecific variation in SMR is thus linked to variation in digestive strategies, although the costs and benefits of a given SMR are likely to vary with resource availability and predictability. Ventilation frequency was shown to be a good correlate of MR, since MR was found to correlate strongly with VR in all fish tested, at all temperatures and the relationship was independent of causal factor. The relationship was linear, and both the slope and corresponding intercept of the regression equation were strongly dependent on the fish’s body weight and the test temperature. Visual measurements of VR may therefore provide a highly accurate, cheap and non-invasive method of measuring the energy consumption of fish engaged in natural behaviours. Comparing SMR of individual fish when alone with response to presence and absence of physical shelters showed that all fish exhibited a reduction in SMR when provided with an appropriate shelter. However, when grouped, there were both positive and negative group effects on SMR depending on the relative size of fish. The consequences are that, although the group effect on SMR may be small on average, at the population level it is large, of variable sign and profoundly important in terms of the overall energy budget at the individual level. This thesis therefore shows that metabolic rates can vary extensively within as well as between individuals, depending on the context, and this variation will have profound effects on overall energy budgets

UK Upland Waters Monitoring Network (UKUWMN) Llyn Llagi, Llyn Cwm Mynach, Afon Hafren and Afon Gwy Annual Summary Progress Report April 2016 - March 2017

The funded chemical and biological sample collection, analysis and data collation, quality control and archiving proceeded without any problems at Llyn Llagi during the period from April 2016 to March 2017. In February 2017 the outflow logger and stageboard were removed pending building works for a National Trust micro-hydro scheme at the site. Subsequently plans for the scheme were withdrawn and it is hoped that the equipment can be reinstalled at the original location

UK Upland Waters Monitoring Network (UKUWMN) - Contract 22 01 249 Llyn Llagi, Llyn Cwm Mynach, Afon Hafren and Afon Gwy Annual Summary Progress Report April 2014 - March 2015

Chemical and biological sample collection, analysis and data collation, quality control and archiving proceeded without any problems at Llyn Llagi during the period from April 2014 to March 2015. Sponge samples from the site, collected in 2012 and sent off to Karen Evans, a PhD student at Liverpool University, were identified as being of two species, Spongilla lacustris and Racekiela ryderii

Integration of juvenile habitat quality and river connectivity models to understand and prioritise the management of barriers for Atlantic salmon populations across spatial scales

Thanks to the Scottish Government Hydro Nation Scholarship programme for funding WBB. Authors from Marine Scotland Science Freshwater Fisheries Laboratories delivered this work through Service Level Agreement FW02G. Some map features are based on digital spatial data licensed from CEH, NERC© Crown Copyright and database right (2018), all rights reserved. Ordnance Survey License number 100024655. Catchment boundaries were from SEPA (2009). The Obstacles to Fish Migration dataset is from SEPA. The authors thank the two anonymous referees for their feedback on the manuscript.Peer reviewedPostprin

Digestive and locomotor capacity show opposing responses to changing food availability in an ambush predatory fish

Metabolic rates vary widely within species, but little is known about how variation in the “floor” (i.e. standard metabolic rate in ectotherms; SMR) and “ceiling” (maximum metabolic rate; MMR) for an individual's aerobic scope (AS) are linked with the digestive and locomotor function. Any links among metabolic traits and aspects of physiological performance may also be modulated by fluctuations in food availability. This study followed changes in SMR, MMR, and digestive and locomotor capacity in Southern catfish (Silurus meridionalis) throughout 15 days of food deprivation and 15 days of refeeding. Individuals down-regulated SMR during food deprivation and showed only a 10% body mass decrease during this time. While critical swim speed (Ucrit), was robust to food-deprivation, digestive function decreased after fasting with a reduced peak oxygen uptake during specific dynamic action (SDA) and prolonged SDA duration. During refeeding, individuals displayed rapid growth and digestive function recovered to pre-fasting levels. However, refed fish showed a lower Ucrit than would be expected for their increased body length and in comparison to measures at the start of the study. Reduced swimming ability may be a consequence of compensatory growth: growth rate was negatively correlated with changes in Ucrit during refeeding. Southern catfish down-regulate digestive function to reduce energy expenditure during food deprivation, but regain digestive capacity during refeeding, potentially at the cost of decreased swimming performance. The plasticity of maintenance requirements suggests that SMR is a key fitness trait for in this ambush predator. Shifts in trait correlations with food availability suggest that the potential for correlated selection may depend on context

There or not there? A multidisciplinary review and research agenda on the impact of transparent barriers on human perception, action, and social behavior

Contains fulltext : 145066.pdf (publisher's version ) (Open Access)Through advances in production and treatment technologies, transparent glass has become an increasingly versatile material and a global hallmark of modern architecture. In the shape of invisible barriers, it defines spaces while simultaneously shaping their lighting, noise, and climate conditions. Despite these unique architectural qualities, little is known regarding the human experience with glass barriers. Is a material that has been described as being simultaneously there and not there from an architectural perspective, actually there and/or not there from perceptual, behavioral, and social points of view? In this article, we review systematic observations and experimental studies that explore the impact of transparent barriers on human cognition and action. In doing so, the importance of empirical and multidisciplinary approaches to inform the use of glass in contemporary architecture is highlighted and key questions for future inquiry are identified.17 p