Obesogens in a naturally obese animal: An experimental approach to assess the impact of marine pollutants on fat tissue function in seals

The ability of organisms to survive and thrive in a changing and increasingly exploited and polluted environment depends on appropriate regulation of energy balance. Growing evidence suggests that exposure to pollutants can alter how fat is stored and used in humans and in other animals. Recent research in humans suggests that many marine pollutants can interfere with the way fat tissue responds to hormonal signals. In particular, pollutants make it difficult to lose weight by switching on pathways that increase fat storage, and this could contribute to problems like diabetes and obesity. Large amounts of persistent organic pollutants (POPs) were made in the early part of the 20th century for use in high capacity electrical conductors and inks, insulators and plastics. Although many POPs are not made anymore because they are very toxic, they are extremely stable and remain in the environment for a long time, ending up in the sea from transport in air and water. Other pollutants, such as phthalates, which are important plasticisers, easily make their way into the sea in run off from urban areas and from marine litter. In particular, POPs do not break down very easily, accumulate in fat and become more concentrated as they are passed up the food chain, ending up in liver and fat. Seals are important top marine predators that have to build up a thick blubber layer while feeding at sea, and then use the fat as a metabolic fuel to keep them alive when they come ashore to breed, moult and rest. They have metabolic similarities to obese and diabetic patients. Their need to rely on fat for fuel and insulation makes them vulnerable to the effects of marine pollutants on the way fat tissue works. The higher the level of POPs in the blubber of seal pups, the lower their chance of survival. Fat tissue like blubber is important for storing fat, releasing it into the bloodstream for use by other parts of the body and producing fat-regulating hormones that control how much fat is stored or used. Recently, the genes of some fat-regulating hormones were shown to be switched on more in blubber of seals from polluted areas in the Baltic Sea than in clean areas in the Arctic, suggesting marine pollutants alter energy balance in seals. However, the mechanisms that control how fat tissue works in seals, and the way marine contaminants interfere with this control, are not well understood. If contaminants can prevent seals from releasing fat from blubber to give them fuel when they are fasting on land, they may have to use more of their protein from muscle tissue instead. This could put them at risk of starvation during moulting, breeding and development, even when they are fat. We will investigate whether pollutants alter fat storage and mobilisation in young grey seals, which are most at risk. We will take small blubber samples from live feeding and fasting seals, without harming them, and treat the blubber with pollutants and fat regulating hormones. We will measure levels of genes and hormones involved in energy balance, the ability of blubber to release fat, and its metabolic rate. By comparing these measures between treatments we will begin to find out how energy balance is normally regulated in seals, how it is altered by marine contaminants, and whether seals are more vulnerable during feeding or fasting. This will help predict the effects of pollutants on seal population size, by contributing a better understanding of how contaminants affect survival of young seals and change their energetic requirements. Because seals naturally experience extreme changes in fat mass, have metabolic similarities to diabetes and obesity, and eat fish, like people do, this work will also inform the likely impacts of POPs and phthalates on human fat regulation. This work has far reaching consequences for health and survivorship in seals and other animals, but also for the management of obesity, diabetes and related metabolic abnormalities in humans.

The main beneficiaries of our work will be advisors and policy makers in marine protection and prevention of obesity. The outputs will ultimately benefit those with a duty to protect vulnerable marine ecosystems and preserve the marine environment against pollution under UN General Assembly resolution 67/70, and those who provide advice to such bodies e.g. the International Council for the Exploration of the Sea (ICES). This includes ICES Working Groups on Marine Mammal Ecology (WGMME) and Biological Effects on Contaminants (WGBEC). Our outputs will reach relevant national government departments and advisory bodies including the Special Committee on Seals (SCOS), the Department for Environment Food and Rural Affairs (DEFRA); Marine Scotland Policy and Planning; Natural England and Natural Resources Wales, and interest overseas agencies such as Department of Fisheries and Oceans (DFO), Canada. They will interest European (Convention for the protection of the marine environment of the North West Atlantic (OSPAR) commission) and global (ICES) intergovernmental agencies, who will be able to use the information to interpret seal population "biodiversity" indicators and "clean and safe" contaminant indicators of Good Environmental Status (GES) in the European Marine Framework Strategy Directive (MFSD). The public will benefit from more effective policy and environmental monitoring, which will facilitate Government's commitment to clean, healthy, safe, productive and biologically diverse oceans and seas. This will indirectly improve quality of life by ensuring sustainable management of marine resources, better policing of legacy and emerging contaminants in marine food webs and maintaining the natural capital of the seas.
Policy makers and advocacy groups targeting the obesity epidemic, particularly those with a duty to prevent and control non-communicable diseases under UN General Assembly resolution 66/2, including the World Health Organisation (WHO), will benefit. The European Association of the Study of Obesity (EASO), and its UK subsidiary, ASO, promote multidisciplinary approaches to obesity research and management, provide a discussion forum and aim to maximise uptake and public benefit of research. Through membership of ASO, we will ensure the outputs are available to EASO, the foremost European scientific and practice-based organisation of professionals in obesity prevention, with formal relations with WHO regional offices and membership of the World Obesity Federation (WOF). Information and advice arising from the project has the potential to influence policy and interventions that would benefit health care providers and advisory groups, such as the National Health Service (NHS), and the National Institute for Health and Care Excellence (NICE). End users, including the UK population, and groups with high dietary contaminant exposure risk will benefit from increased quality of life through advice on obesity prevention, which could have positive economic effects by alleviating strain on health care providers.
Impact through training includes development of technical skills used across disciplines and in public and private sectors. Timely training in media engagement and how science informs policy will have societal impact by increasing the effectiveness of communication by the project team, producing positive effects on public understanding of science and uptake of science into advice to government.
Schools, public outreach, and citizen science organisations will benefit from resources and information we produce and activities such as annual public lectures, visits to schools, participation in Bioblitz and national science events, such as Soapbox Science. Conservation organisations and groups advocating reduced use of plasticisers and other chemicals will find the project useful in identifying where pressure may be needed on Government to address issues of legacy and emerging contaminants on ecosystem and human health.