The impact of climate change on Arctic food webs: a molecular approach

The Arctic Ocean is undergoing rapid change with unknown consequences for its ecosystems. Since 1978, Arctic sea ice has decreased by 9% per decade. The Arctic is warming twice as fast as the global average. Arctic primary productivity has increased by 30% from 1998 to 2012. These stressors have led to regional changes in phytoplankton community size structure and diversity, which will have knock on effects on secondary production by zooplankton and higher trophic levels in the food web. Understanding how entire food webs are being reshaped in response to these environmental stressors is crucial in understanding the impacts of future change on Arctic ecosystems.
Mesozooplankton represent the dominant component of secondary production in marine ecosystems, copepods often forming the principle biomass of zooplankton assemblages. Mesozooplankton feed on diatoms, a large celled photosynthetic phytoplankton group. Rising Arctic temperatures are reducing the nutrient supply, which is favouring smaller phytoplankton, leading to a more complex, microbially based food web. Larger, colder-water zooplankton species are declining and being replaced by smaller, less nutritious species. These changes may alter the abundance and quality of food available to higher trophic levels, such as Arctic seals and thus have important implications for Arctic food webs.
The central hypothesis of this PhD project is that environmental change has significantly altered the size structure and feeding habits of Arctic zooplankton over the past decade. This hypothesis will be tested by using time-series (2008 to present) zooplankton samples from the northern most route of the Continuous Plankton Recorder (CPR) from Tromso to Svalbard (How about a figure of this below?). A novel dual biomarker approach will be used to determine if the food source of Arctic zooplankton has changed and if their trophic position has changed over the past decade. Molecular analysis of gut contents will be carried out to determine prey composition of zooplankton, whilst compound-specific 15N-amino acids in zooplankton will be used to estimate trophic position. This will be complimented by analysis of zooplankton species composition and abundance. Zooplankton data sets will be compared to variations in phytoplankton biomass, productivity and sea ice from remote sensing datasets giving insight into how Arctic zooplankton communities are affected by environmental change.

The main beneficiaries of this project will be policy makers concerned with conservation of Arctic marine mammals, Inuit communities, school pupils, teachers and the wider general public.

Throughout much of their range, seals and other mammals are important cultural and nutritional resources for indigenous and non-indigenous communities. However, seals are being measurably impacted by climate change. Our project will provide observational and modelling evidence regarding the drivers of alterations to seals' trophic position, food web structure or foraging behaviour over decadal time scales. Using multiple tools, we will delineate if changes in seal trophic position, food chain length or foraging behaviour are due to environmental factors (e.g. sea ice changes), variations in the base of the food web (e.g. from reduced nutrient supply) or the addition of new trophic levels (e.g. migration of boreal species). Our work directly benefits ongoing programmes that monitor the Arctic, such as the Five-year Science Research Agenda from the Department of Fisheries and Oceans (Canada). Our work will benefit work by DFO and aid Inuit communities develop adaptation strategies (Letter of Support from Ferguson, DFO). We will disseminate results from our project to key international organisations, such as the International Council for Exploration of the Seas (ICES) and North Atlantic Marine Mammal Commission (NAMMCO), facilitated by NAMMCO General Secretary and project partner, Desportes. Other project partners (Stenson, Hammill, Ferguson and Hop) are also involved in ICES and NAMMCO, as well as the Circumpolar Biodiversity Monitoring Programme (CBMP), making them able to disseminate our results in the context of management and policy. A one year PDRA will collate, analyse and model historical data on harp and ringed seal body condition and fecundity alongside environmental variables and determine the factors driving long term change in seal populations, disseminating their findings to ICES and NAMMCO at international meetings. This will allow the practical and applied project outputs to inform management and policy for marine mammals in the Arctic, with the potential to affect future decision making for seal populations. Thus, we directly address NERC strategy by providing tools for the 'Management of Environmental Change'.

It is essential that our research outcomes are disseminated to the UK community. This is challenging but vital to recruit students into sciences, convince the public that it is worthwhile funding this type of research and increase awareness of the sensitivity of the Arctic to a changing climate. Our project will provide teachers with tools to demonstrate key concepts in our research programme. To this end, we will produce three posters to convey for example, 'Arctic food webs', 'Stable isotopes in Arctic ecology' and 'Impact of climate change on the Arctic' to school pupils in order to demonstrate how food webs operate in the Arctic. Posters will be hand-drawn by a visual artist with experience of communicating complex ideas concisely and digitized by co-PI Heath.

The general public tends to engage with popular wild life television programmes that illustrate the fauna of the Arctic and the pressures imposed by climate change. We will explain the vital role of microscopic phytoplankton and nutrients within the environment by creating one short accessible scored video, with combinations of film, hand and digital animations with commentaries aimed at the general public. The video will be distributed via a project YouTube channel and via our own website.

At the programme level we suggest (a) creating a dedicated programme website and social media outlets, (b) soliciting the BBC or Discovery Channel to produce a short documentary about the programme and (c) hiring an expert in science communication and impact to represent the programme and/or train members of the research programme in science communication.