Given the increasing rate of environmental change that free-living animals are exposed to, there is a growing need to understand the causes and consequences of environmentally-induced phenotypic change and to what extent this phenotypic plasticity is adaptive. As well as being of fundamental biological significance, this knowledge is necessary for the development of effective conservation policies. This thesis examines variation in behavioural, morphological and physiological responses to repeated exposure to environmental stressors. In particular, I focus on early-life effects and discuss the potential consequences of developmental plasticity for later-life performance. Although negative effects of human disturbance on wild animals have been widely reported, few studies have considered the potential for effects on animals occupying burrows or cavities. Procellariiform seabirds are among the most globally-threatened avian taxa and include many species that nest underground. Human disturbance is one of the main threats they face, yet breeding colonies attract increasing numbers of tourists. The European storm petrel Hydrobates pelagicus is a small seabird, belonging to the Procellariiformes, that nests in cavities and is strictly nocturnally active at the breeding colony. The UK’s largest storm petrel colony at Mousa, Shetland, offers a novel system for investigating the potential impacts of human recreational disturbance on a cavity-dwelling animal and the capacity for environmentally-induced developmental plasticity within the remarkably slow development strategy displayed by nestlings. I show that, despite remaining out of sight, human disturbance above ground can have profound effects on cavity-dwelling animals. Nestling survival was significantly lower in areas exposed to high levels of human recreational activity, compared with those reared in areas subject to very low levels of visitor activity (Chapter 1). Furthermore, disturbed nestlings that survived to fledging displayed depressed growth rates (Chapter 2). Plasticity in developmental pathways, however, enabled nestlings to mitigate for poor growth conditions by prioritising energy allocation to structural components and extending the growth period. While such growth plasticity can be adaptive and avoid short-term costs, there may also be long-term costs associated with this strategy. Repeated exposure to stressors can give rise to chronic stress and measures of baseline glucocorticoids are widely considered to be useful for detecting stress in natural populations. Nestlings displayed no evidence for chronic stress, as measured by baseline corticosterone (the main glucocorticoid in birds), in response to repeated exposure to human recreational disturbance (Chapter 2) or investigator handling (Chapter 3). Furthermore, baseline corticosterone did not reflect the differences observed in growth trajectories between the two disturbance categories. Although it is unknown whether the induced changes in growth trajectories of high-disturbance nestlings carry costs, the lack of any effects on corticosterone levels suggests that glucocorticoids are not always an informative measure of individual state. Additional behavioural and physiological data are required to develop an integrated understanding of phenotypic responses to environmental cues. Besides immediate effects on growth and survival, it is well known that conditions experienced during early life can have profound influences on later-life performance. Telomere dynamics potentially provide a mechanistic link between the early environment and fitness outcomes. I show that environmental conditions during growth strongly influence early-life telomere dynamics of entire cohorts, and early-life telomere length is a good predictor of imminent mortality (Chapter 4). Natural variation in the natal environment can lead to marked differences in life-history traits between cohorts and telomere dynamics may be one of the mechanisms underlying cohort effects observed in nature. Unfavourable natal conditions were also associated with the occurrence of hypothermic responses in nestlings (Chapter 5). Such thermoregulatory responses may be adaptive, by facilitating survival during periods of food shortage or cold, but nonetheless could carry costs for growth and long-term fitness. An enhanced knowledge of the causes and consequences of facultative hypothermic responses can advance our understanding of the effects of environmental change. Understanding and predicting how populations will respond to environmental change, however, requires accurate estimation of population size. The ecology of Procellariiformes presents a major challenge to achieving this. Using spatially-explicit capture-recapture data from three closely-related species of storm petrel, it was shown that capture probability varies across spatial and temporal scales (Chapter 6). This quantified variation was used to inform optimal sampling strategies. The results demonstrate that spatially-explicit capture-recapture models can be effectively used to monitor vulnerable burrowing seabird populations, but require a species-specific approach. This thesis addresses key questions concerning the capacity for adaptation and response to environmental stress exposure and the mechanisms underlying individual variation in responses. I demonstrate that multidisciplinary studies of behaviour, morphology and physiology are required to develop an integrated understanding of responses to environmental stressors.

The work presented in this thesis was carried as part of a project to improve the analysis of clinical data obtained by microwave thermography. For microwave thermography measurements to be usefully interpreted for detecting thermal anomalies in the human body at depths of up to several centimetres, the thermal and microwave dielectric properties of tissues must be known. This thesis is mainly concerned with the measurement and interpretation of the values of the thermal conductivity and diffusivity of human and animal tissues. The thermal properties of biological tissue are required, in conjunction with a bio-heat equation, to allow the formation of computational models to simulate the temperature distribution inside the human body. These computational models are also useful in the analysis of tomographic temperature measurements, and are essential to ensure accurate heating in hyperthermia. The Pennes conventional bio-heat equation has proven to be successful in analysing the data produced by microwave thermography. The thermal properties of biological soft tissue are dependant on the tissue water content. Water is a major constituent of most soft biological tissues, and it has a higher thermal conductivity and thermal diffusivity than any other constituent of biological tissue. The thermal properties of biological tissue can be modelled using a mixture equation, which describes the behaviour of a two phase system in terms of the thermal properties of the individual constituents and their relative volume fractions. This allows the variation of the thermal properties of biological tissue with water content to be analysed. A self-heating thermistor probe system was used in this study to measure the in-vitro thermal conductivity and thermal diffusivity of a wide variety of human and animal tissues. The system was calibrated using glycerol and agar-gelled water since the thermal behaviour of these materials and mixtures of these materials was well known. The calibration data was examined to determine the accuracy of the calibration and to determine if there was a relationship between the observed thermal conductivity and thermal diffusivity which was generated by the measurement system

Nephrops norvegicus is a mid-sized benthic decapod lobster found at depths of between 30-300 metres along the eastern Atlantic coast from Norway to Morocco, and within the Mediterranean sea. They inhabit marine muddy sediments in which they excavate burrow systems and from which they make short excursions to feed by predation and scavenging. The females of this species are known to reside within their burrows over the winter period while brooding their eggs, although their feeding behaviour over this period has not been investigated. Two aspects of the nutrition of N. norvegicus, namely nutritional status (the condition of an animal, which is maintained through a balance between energy intake and energy expenditure) and trophic dynamics (the flow of energy from exogenous inputs throughout food webs in an ecosystem) have been studied, to answer questions relating to the influence of season, sex and site on nutrition in this species. Specific questions that have been addressed include: with regard to season, is there a reduction in the nutritional status of N. norvegicus over the winter due to a decrease in primary production? With regard to sex, do females have a reduced nutritional status to males when they emerge from their winter brooding period, indicating that females go through a period of fasting over the winter? Also do females employ a filter feeding strategy over the winter? With regard to site, do N. norvegicus at two different sites on the west coast of Scotland (i.e. the Clyde Sea Area [CSA] and the North Minch [NM]) occupy different trophic levels and have different fatty acid signatures, which would indicate that their diets are made up of different prey species? A range of biochemical markers was tested to describe how N. norvegicus reacts to a period of forced starvation, and thus to determine their nutritional status. There was clear metabolic depression, indicated by an increase in the copper concentration of the hepatopancreas in both males and females. In contrast to the findings of previous studies, lipids in the hepatopancreas did decrease with starvation, however was mitigated by the metabolic depression and only became significantly lower than fed individuals after 12 weeks in males and 20 weeks in females. Lipids and water combined made up 80% of the mass of the hepatopancreas, and when the lipids decreased the proportional mass was replaced by water. However, as indicated by the hepatosomatic index (HSI), the total mass of the hepatopancreas decreased over the period of starvation. A temperature effect was also seen which influenced the amount of reserves required by the animal under these conditions. Using the results from the starvation trials, a predictive tool was developed for determining the nutritional status in N. norvegicus from the wild, and for calculating threshold values which indicate whether animals were in a starved state. These measurements and threshold values were applied to field caught animals, assessing the factors of season, sex and site. The seasonal analysis showed that there was low nutritional status in N. norvegicus during the winter of 2008-2009, whereas the nutritional status of winter 2009-2010 was not as low. The site analysis showed that N. norvegicus in the CSA, where burrow density is 0.85 m-2, were found to have a lower nutritional status than N. norvegicus in the NM, where burrow density was only 0.55 m-2. These results are consistent with the notion that in high density areas N. norvegicus has a lower nutritional status than in low density areas. Females were found to have a larger lipid store within the hepatopancreas than males, presumably to sustain reproduction. Females were also found to be metabolically depressed over the winter and spring months of early 2009. However they were not in an advanced state of starvation over this period. It is therefore concluded that over the winter months females reduce feeding, perhaps in a response to reduced mobility brought about by the brooding stage of reproduction, but do not follow different feeding strategies to males over this time. The differences of trophic level between N. norvegicus in the CSA and the NM were assessed through the use of stable isotope analysis. It was found that although the animals in the CSA had higher 15N values than the animals in the NM, the animals in the NM were actually feeding at 0.6 trophic level units higher than those in the CSA. The high 15N values in the CSA were ascribed to organic enrichment of nitrates in that area. There was no significant difference between males and females at the end of the winter period, indicating that when females are brooding their eggs they do not use different feeding strategies (e.g. filter feeding) as an alternative means of nutrition. The differences between the Fatty Acid (FA) signatures of N. norvegicus in the CSA and the NM were determined by fatty acid analysis. A clear difference was demonstrated between sites, indicative of differences in the dietary composition of the two populations, and suggestive of a greater input from pelagic food sources (either zooplankton or fish) in the NM. However, no significant difference was found in FA signatures between male and female N. norvegicus at either site or at any time of the year. Thus, consistent with the conclusions from the other monitoring methods, the FA signatures indicate that females and males had similar feeding patterns at all times of year, with regard to the type of food consumed. As well as addressing issues directly concerned with the nutrition of N. norvegicus in relation to season, sex and site, the results of these studies have a number of wider applications, including the development of optimal feeding strategies for holding lobsters under impoundment conditions for long periods, and for identifying the procedures required to assess more directly the dietary composition of N. norvegicus populations, and especially the contribution of fish to their diet.

Stereotypic behaviour is characterised as repetitive, topographically invariant, rigid behaviour patterns, often displayed by captive, domestic and laboratory animals. The cause of these behaviours is thought primarily to be related to impoverished or species-atypical living environments, but recent research has outlined a neural phenotype, relating to basal ganglia dopamine physiology, which is common to several species. One species displaying the neural and associated behavioural phenotypes is the Horse. The purpose of this thesis was to explore, through behavioural assays, the behavioural phenotypes associated with endogenous basal ganglia dysfunction as a neural feature of equine oral stereotypy. In the first study, the behavioural effects of one aspect of the neural phenotype – downregualtion of dopamine transmission in the nigrostriatal pathways – were examined. Animals with the medial aspect of the dorsal striatum lesioned have been shown to exhibit learning differences in spatial navigation procedures. Employing two dry-maze procedures, stereotypic and control horses were required to locate food in different locations. No specific differences between the groups were found, but the stereotypic group were found to be less exploratory and tended to adopt ‘habitual’ response patterns. In the next studies, the behavioural effects of a further feature of the neural phenotype – upregulation of mesoaccumbens dopamine transmission – were examined. Chronic amphetamine exposure leads to a similar neural phenotype, and this offered an interesting hypothesis in the context of the endogenous change reported in stereotypic horses. A Pavlovian to Instrumental Transfer task was initially employed, in which horses were first trained in a Pavolvian procedure, and subsequently trained to perform an instrumental response, reinforced by the same food as in the Pavlovian phase. In the transfer phase, the Pavlovian conditioned stimulus was introduced in the context of the instrumental responding. It was predicted that response rates would increase during the transfer phase; however, the results were inconclusive. In the third study, further behavioural effects of increased mesoaccumbens dopamine were tested by employing an instrumental choice procedure. Stereotypic horses and controls were trained to choose between two mutually-exclusive schedules of reinforcement, one associated with a short delay to gain food and one with a longer delay. Chronic amphetamine exposure leads to a decrease in sensitivity to delay, and it was demonstrated that stereotypic horses showed similar patterns, failing to choose the shorter schedule. Finally, increased dopamine transmission is known to enhance the rate at which learning shifts from planned-action to habit, and this was examined in stereotypic horses using a ‘place-response’ preparation. Evidence was found to support this hypothesis in two variations of this procedure. The latter findings suggested an imbalance of the constituent cells that form the striatum: the striosome and matrix components. Taking this in conjunction with the other findings, this imbalance may hold the key to identifying the aetiology of stereotypic behaviour.

Tree frogs have evolved specialised toe pads which allow them to efficiently climb vertical surfaces. The toe pad stick by using ‘wet adhesion’ – a combination of forces produced by a thin layer of fluid between the pad and the surface which provide temporary adhesion to allow quick attachment and detachment for climbing. Most studies on tree frogs have been based on their adhesive capabilities on surfaces which are flat, clean and dry (usually glass). However, climbing tree frogs in the wild will come across a variety of surfaces which could affect their adhesive abilities. This PhD investigated whether tree frog adhesion is affected by various ‘challenging’ surfaces, which reflect conditions that tree frogs may encounter whilst climbing. These include rough surfaces, wet conditions, surfaces with loose particulate and hydrophobic surfaces. Experiments were predominantly conducted using a force transducer to measure adhesive and frictional forces of single toe pads, as well as whole animal attachment experiments involving a rotating tilting board. The toe pads of tree frogs were shown to possess a self-cleaning mechanism, whereby the pads will remove contaminants (and subsequently recover adhesive forces) through repeated use, thanks to shear movements of the pad and the presence of pad fluid which aids contaminant deposition. To investigate how torrent frogs (frogs which inhabit waterfalls) can adhere to rough and flooded surfaces, the performance of torrent frogs species Staurois guttatus was compared to a tree frog species (Rhacophorus pardalis). Torrent frogs could produce higher adhesive forces than tree frogs with their toe pads, and possess a specialised toe pad morphology (directional fluid channels on the pad periphery) which may contribute to better performance in flooded conditions. Torrent frogs utilise large areas of ventral skin to stay attached on overhanging surfaces, while tree frogs display a reduction in contact area resulting in a failure to stay attached. This combination of ability and behaviour will help torrent frogs to stay attached on the rough and flooded surfaces that make up their waterfall habitat. On rough surfaces, tree frogs showed improved (compared to smooth surface performance) performance on smaller scale roughness (asperity size <10 µm), and poorer performance on the larger scale roughnesses tested (30 – 425 µm). Interference reflection microscopy (IRM) revealed that larger asperities result in pad fluid being unable to fill the larger gaps of such surfaces, which was confirmed by adding water to rough surfaces to improve attachment performance. The soft pad does however aid in conforming to some rough surfaces, which could account for the better performance on the smaller scale roughness. Many plant surfaces exhibit hydrophobic properties, and so the adhesive performance of tree frogs on hydrophobic surfaces was compared to that on hydrophilic surfaces. It was found that the toe pads could produce similar adhesive and frictional forces on both surfaces. The pad fluids contact angles were then measured on hydrophobic surfaces using IRM, where droplets of pad fluid formed lower contact angles (and are therefore exhibiting higher wettability) than water. Though the exact composition of pad fluid is unknown, some form of surfactant must be present which aids wetting of surfaces (either a surface modification or detergent present in the fluid) to allow wet adhesion to occur - goniometer experiments of water on dried footprints on hydrophobic surfaces confirmed this. The ability to stick in a variety of conditions could provide inspiration for ‘smart’ adhesives, which mimic the adaptable adhesion of tree frog toe pads.

This thesis describes a study into two post capture conditions, idiopathic muscle necrosis (IMN) and a post capture opportunistic bacterial infection, affecting the Norway lobster, Nephrops norvegicus, and a comprehensive analysis of the stressors involved in the capture and post capture periods of the fishery process. A multivariate approach was used to study progression in the post capture condition of trawl-caught N. norvegicus for the live transport market. Prolonged periods of aerial exposure resulted in large disruptions to the carbohydrate profile, increases in haemolymph L-lactate and crustacean hyperglycaemic hormone concentrations, and corresponding fluctuations in haemolymph pH. These disruptions increased with the increasing temperature of aerial exposure, which impacted the immunocompetence of the lobsters: circulating haemocytes and phenoloxidase levels were significantly reduced and the degree of bacteraemia increased. The health status of N. norvegicus captured during trials in spring and autumn by means of short trawl (1h duration), long trawl (5h duration) and creeling was assessed using a range of physiological (Haemolymph L-lactate, crustacean hyperglycaemic hormone (CHH), abdominal muscle glycogen concentrations), immunological (total haemocyte counts (THC)) and physical (mortality, damage indices) parameters. Increased duration of trawl did not significantly alter physiological parameters, while time of landing did have a significant effect on L-lactate, where animals landed in the morning exhibited higher concentrations. Seasonal variations in abdominal muscle glycogen concentrations were also apparent. Irrespective of season, individuals captured by short trawls in the morning suffered lowest mortalities. Damage assessment data revealed that a greater proportion of individuals were categorised as heavily damaged following longer trawls conducted in spring. The carbohydrate profile and immunocompetence of N. norvegicus was significantly affected following trawl capture and subsequent handling and aerial exposure post capture. The recovery period was investigated through a range of parameters (L-lactate, glycogen, glucose, THC) and the data suggested that animals should be submerged and unstressed for at least 24h following capture and handling to avoid further alterations to the carbohydrate profile and reduce the window of opportunity for invading bacteria to cause meat spoilage. The influence of air temperature on the condition of N. norvegicus caught for the live export market was assessed by correlating meteorological data with the percentage of catch accepted for live transport. Results illustrated a large degree of variability in the conditions of animals on arrival at the processing plant. Air temperature was the only meteorological factor that had an impact on the morbidity and mortality of the catch. In one instance in particular, mean air temperature on the day of capture had a significant negative impact on the health of the catch.

Heart rate (f\(_H\)) and rate of oxygen ( V\(_{O2}\) consumption were recorded from adult macaroni penguins while exercising on a treadmill. No differences were found in the relationship between f\(_H\) and V\(_{O2}\) in breeding and moulting female penguins, but a significant difference was found between male and female penguins. These relationships were used to estimate field metabolic rate (FMR) for free-ranging female penguins, which were implanted with heart rate and temperature data loggers. While foraging to provision their chick, FMR was 8.92 ± 0.44 W kg\(^{-1}\) and 9.07 ± 0.42 W kg\(^{-1}\) respectively while at-sea during the brood and crèche phases of the breeding season. While on-shore, the FMR was 6.08 ± 0.43 W kg\(^{-1}\) and 5.64 ± 0.40 W kg\(^{-1}\) respectively for the brood and crèche phases. During their moult fast, male and female penguins showed a pattern of increasing and then decreasing FMR and females had a mean FMR of 5.25 ± 0.88 W kg\(^{-1}\). The peak of energy expenditure was associated with maximum feather loss, probably due to increased costs of thermoregulation. During natural diving, penguins showed complex fluctuations in heart rate. Abdominal temperature fell during dive bouts with the magnitude of this decline increasing with bout length. Put together, these adjustments in heart rate and circulation may be enough to enable all natural dives to be aerobic in nature.