Assessment of disease status in fish is used as an indicator of the biological effects of contaminants in the marine environment. At some UK offshore sites the prevalence of liver tumours in Limanda limanda (dab) exceeds 20%. However, the molecular mechanisms of tumour formation and the causative agents are not known. The contribution of epigenetic mechanisms, although well-established in human tumourigenesis, is under-studied in tumours of aquatic species. In this thesis, alteration in the DNA methylation patterns in tumours of two fish species, the model species zebrafish (Danio rerio) and the un-sequenced marine flatfish dab, were investigated. The data presented provided a comprehensive characterisation of DNA methylation pattern in zebrafish liver and the first evidence of alterations in DNA methylation profiles of key genes in tumourigenesis pathways in any aquatic species. A statistically significant lower level of global DNA methylation was demonstrated in hepatocellular adenoma (HCA) and non-cancerous surrounding liver tissue (ST) compared to liver of non-cancer bearing dab. The evidence presented in this thesis suggests that chronic exposure to a mixture of pollutants contribute to global DNA hypomethylation followed by further epigenetic and genomic changes, leading to the development of tumours in dab. These findings suggest a link between the environment, epigenome and cancer in fish tumours in the wild.

UK consumers bought just under 500 thousand tonnes of seafood in 2010, at a cost of £3.8bn. Despite rising prices, consumption is on a general upwards path, with the average UK adult now eating 2% more seafood than they would have eaten a generation ago, and demand predicted to grow by a further 17% by 2030. However, this demand is increasingly restricted to a narrow range of imported and wild-caught species (Cod, Haddock, Tuna) and farmed products (Salmon and Prawns) over locally-available species with the consequence that between 60% and 80% of UK domestic landings are currently exported and 80% of all the seafood eaten in the UK is one of either Cod, Haddock, Salmon, Tuna or Prawns – the so-called Big 5. The shortage of local markets for native fish species is arguably reducing the relative viability of small scale, over large-scale, fisheries in the UK. It also increases pressure upon wild stocks of commercially valuable species and is driving the rapid expansion of fish-farming operations which can have negative environmental and social implications. Considering the above, it is suggested that UK consumers could make a positive contribution to the UK economy and marine environment if they chose to buy native, locally-caught species, over farmed and exotic imports. In order to achieve this, however, significant behavioural change would need to take place; and for behavioural change initiatives to be successful, it is argued that it is first necessary to understand why these consumption patterns have developed, i.e. Why the Big 5? Accepting that no single theory has been found that can fully explain behaviours from intentions, this research used mixed methods to develop a consumer-centric view of the full range of factors that might be driving these unsustainable consumption patterns. Regular consumers of seafood from four contrasting localities in England were recruited to complete surveys, maintain shopping diaries and to take part in group and one-to-one interviews to understand their reasons for eating seafood in general and the Big 5 in particular. Drawing on the Literature on seafood consumption, demographic and geographic-induced differences in consumption were explored; and consumer understanding of, and concern for, the sustainability of their seafood was assessed. Retail behaviour was also examined by undertaking an on-line review of the seafood offered for sale by the UK’s five largest retailers. Consumers were generally ill informed and confused about the sustainability of their seafood and had little to no awareness of labelling. In their confusion/apathy, they tended to revert to habitual behaviours and safe choices tending towards the Big 5. They felt strongly that retailers should be making it easier for them to make sustainable choices. The evidence from this study is that Retail is failing in this respect. Interest in and demand for local seafood was very high, with consumers equating local with sustainable, even though the evidence to support this assertion is currently lacking. Consumer definitions of “local” and “sustainable” were found to vary from accepted policy and academic understanding, presenting the possibility of adding to consumer confusion when communicating about sustainable seafood; further, “sustainable” possessed negative connotations for these consumers who, in stark contrast to the average UK consumer, were found to score highly for Hedonism. In total, twenty eight distinct variables were identified as influencing unsustainable UK seafood consumer behaviour. Key amongst these were consumer ignorance/apathy regarding sustainability; retail behaviour; and habit – factors that are presented in the Trifold Model of Unsustainable Consumer Behaviour. This model brings much needed clarity to a complex and poorly understood area of consumer behaviour and marks a significant contribution to three areas of academic study: Sustainable Consumption; Consumer Behaviour; and Business Ethics. The Trifold Model is presented for further testing. Recommendations for policy and industry are highlighted as are areas for further research.

The research focusses on the river Lugg – a cross-border catchment and major tributary of the river Wye, the most important Atlantic salmon river in England and Wales. The problem of declining Atlantic salmon populations in the catchment is addressed through investigating recruitment from egg fertilization to the emergent life stage and beyond using multiple field-based and laboratory techniques. The approach adopted is multidisciplinary and addresses the need for holistic approaches to habitat degradation which is increasingly recognised as systemic in nature; often with multiple stressors acting interactively. The initial premise of deleterious fine sediment infiltration into spawning gravels was addressed by a sediment fingerprinting study to ascertain the provenance of infiltrated redd sediment from a range of land-use types. In addition, nine artificial redd sites were constructed and assessed for fine sediment infiltration, intragravel dissolved oxygen levels, intragravel flow velocity and other hyporheic pore water characteristics, in relation to survival to emergence over two field seasons. A study examining the quality of emergent fry was also carried out using fitness tests and individual stress levels. Additionally, a study on long-residence groundwater infiltration into the incubation environment was carried out. The main fine sediment contributor was derived from agricultural sources, particularly during wetter periods. The average contribution of fine sediment from agricultural sources was 60%. Survival ranged from 12% to 70% during the 2008 flood season and from 76% - 93% during the 2009 dry season. Fine sediment mass as a stand-alone index was only weakly correlated with survival but is thought to influence other factors; medium strength correlations of survival with dissolved oxygen, intragravel flow velocity and oxygen supply in particular were observed. Evidence of groundwater-surface water interactions were detected at two of three sites investigated and is proposed as an additional controlling mechanism for embryonic survival in the catchment. Sublethal fitness tests demonstrated variations between cohorts in the 2009 period despite a relatively small range of oxygen concentrations. The results highlight both temporal and spatial variations in spawning habitat quality, which influence not only survival to hatch but also posthatch fitness.

Predators can have both direct and indirect effects on how their prey interact with parasites. This thesis explores these effects using observational and experimental approaches. A behavioural experiment suggested that the direct effects of predators are size- and sex-biased, with small and male guppies, Poecilia reticulata Peters 1859, more prone to Gyrodactylus turnbulli Harris 1986 parasite-induced vulnerability to predation (Chapter 2). Trait-mediated indirect effects of predators also appear important to this host-parasite interaction, as revealed by surveys of natural Trinidadian populations under different predation regimes. First, predator-driven life history evolution predicts an apparent population divergence in parasite tolerance (Chapter 3). Similar divergence in a second trait, social behaviour, may drive sex- and age-biased parasitism: the guppies most liable to shoal have the highest infection probability (Chapter 4). Social behaviour is thus an important driver of parasite transmission, but how parasites affect social interactions remains poorly understood. The second part of this thesis investigates how guppies may use sensory information to mitigate this cost of sociality. Many fishes rely on chemical and visual information and the interaction between sensory modalities to behave appropriately; for example, chemical cues change how guppies respond to visual cues (Chapter 5). In a social context, guppies use both chemical and visual cues to detect infection in conspecifics, but only avoid those in the later stages of infection (Chapter 6). Infection avoidance behaviour is not innate, but likely results from juvenile guppies imprinting on cues of conspecifics, and associating with these cues in adulthood (Chapter 7). This imprinting-mediated avoidance appears to be adaptive: a transmission experiment showed that the onset of avoidance behaviour coincides with the stage of infection at which conspecifics are most infectious (Chapter 8). The sensory ecology of the host and the community in which it lives therefore have important implications for disease dynamics.

Based on 10 months’ qualitative fieldwork and the filming of a documentary conducted on the islands of Lampedusa and Fuerteventura, this thesis examines ground-level Europeanisation, concentrating on two well-established Communitarian policy frames -- the Common Fishery Policy (CFP) and the management of the external border of the Schengen space of free movement of people – and two populations of artisanal fishers who were exposed to them. It analyses how governmental logics operated on the ground through individuals’ engagement with Communitarian policies, and it reconstructs the major transformations that the two islands’ fishing industries underwent in the duree of more than fifty years of European integration. While until less than thirty years ago the economy of the Italian island of Lampedusa was centred on bluefish fishing and canning industries, on the Spanish island of Fuerteventura most islanders lived from agriculture for centuries. Following the European integration of Italy and Spain, both islands turned into major tourist destinations and the centres of frequent European migration crises. By focusing on these two territories, this investigation explores how EU governance contributed to transforming the local sociocultural and economic fabric and the islanders’ everyday life. Following the overview of how both policies were played out on the ground, I analyse the effects that the CFP produced on the two islands, and those that the management of the European external border generated in Lampedusa. Giving centrality to the marine element, I push the study of Europeanisation towards the sea and reveal how European policies had reconfigured the islanders’ relation with the seawaters surrounding them. Concurrently, by exploring the ways in which individuals interacted with EU governmentalities, I also unearth the several unintended consequences of Communitarian governance – as conservation policies aiming at recovering overfished fish stocks actually generated the conditions for increasing and uncontrolled overexploitation, while border policies for the securitisation of the European space de facto de-securitized life in Lampedusa.