Suzanne J. Painting

Tracking seasonal changes in North Sea zooplankton trophic dynamics using stable isotopes

Trophodynamics of meso-zooplankton in the North Sea (NS) were assessed at a site in the southern NS, and at a shallow and a deep site in the central NS. Offshore and neritic species from different ecological niches, including Calanus spp., Temora spp. and Sagitta spp., were collected during seven cruises over 14 months from 2007 to 2008. Bulk stable isotope (SI) analysis, phospholipid-derived fatty acid (PLFA) compositions, and δ13CPLFA data of meso-zooplankton and particulate organic matter (POM) were used to describe changes in zooplankton relative trophic positions (RTPs) and trophodynamics. The aim of the study was to test the hypothesis that the RTPs of zooplankton in the North Sea vary spatially and seasonally, in response to hydrographic variability, with the microbial food web playing an important role at times. Zooplankton RTPs tended to be higher during winter and lower during the phytoplankton bloom in spring. RTPs were highest for predators such as Sagitta sp. and Calanus helgolandicus and lowest for small copepods such as Pseudocalanus elongatus and zoea larvae (Brachyura). δ15NPOM-based RTPs were only moderate surrogates for animals’ ecological niches, because of the plasticity in source materials from the herbivorous and the microbial loop food web. Common (16:0) and essential (eicosapentaenoic acid, EPA and docosahexaenoic acid, DHA) structural lipids showed relatively constant abundances. This could be explained by incorporation of PLFAs with δ13C signatures which followed seasonal changes in bulk δ13CPOM and PLFA δ13CPOM signatures. This study highlighted the complementarity of three biogeochemical approaches for trophodynamic studies and substantiated conceptual views of size-based food web analysis, in which small individuals of large species may be functionally equivalent to large individuals of small species. Seasonal and spatial variability was also important in altering the relative importance of the herbivorous and microbial food webs.

Marine Ecosystem Connections: essential indicators of healthy, productive and biologically diverse seas

Welcome to this Special Issue of Biogeochemistry, which highlights the key research findings from a fiveyear study entitled ‘‘Marine Ecosystem Connections: essential indicators of healthy, productive and biologically diverse seas’’. The overall aims of the programme were to improve our scientific understanding of the functioning of shelf seas, develop tools for predicting the impact of human activity on ecosystem structure and function, and contribute to the development of indicators for assessments of ecosystem health and environmental status. Key to these studies was the focus on linkages between benthic and pelagic food webs, in response to environmental drivers (Fig. 1), and an underpinning requirement to link the research on biogeochemical cycling to the development of tools and approaches for improved management of marine resources. Around the world, in countries such as Australia, Canada, China, North America and South Africa, recent policy and legislative drivers require integrated, ecosystem-based assessments of the impacts of human activities (see Borja et al. 2008; Elliott 2011). In Europe, for example, the Marine Strategy Framework Directive (MSFD, CEC 2008) aims to achieve Good Environmental Status (GES) in all water bodies by 2020, and requires that ‘‘the structure, functions and processes of the constituent marine ecosystems’’ allow them ‘‘to function fully and to maintain their resilience to human-induced environmental change’’, taking account of ‘‘associated physiographic, geographic, geological and climatic factors’’. A number of coastal and marine regions, including the North Sea, have therefore become the focus of ongoing research on ecosystem structure and function, and the development of indicators for assessing environmental status (see COM 2010). Studies carried out during ‘Marine Ecosystem Connections’ (MEC) are part of this effort. A combined fieldwork and modelling approach was used to quantify carbon and nitrogen fluxes through pelagic and benthic food webs in the temperate North Sea, to predict the impacts of climate change and demersal trawling on these fluxes (van der Molen et al. 2012), and to select and evaluate indicators of ecosystem functioning in terms of their suitability for assessing and managing the impacts of climate change and demersal trawling (Painting et al. 2012). For the pelagic food web, only lower trophic levels (up to zooplankton) were considered, as they have fast turnover rates and are useful as early warning indicators of environmental change. For the benthic food web, the main functional groups of the faunal communities were considered. Coupled physical-biogeochemical models (GOTM-ERSEM-BFM) were developed to improve their suitability for temperate shelf seas (see van der Molen et al. 2012), e.g. through parameterisation to allow growth of diatoms S. J. Painting (&) R. M. Forster Centre for Environment, Fisheries and Aquaculture Science (Cefas), Pakefield Road, Lowestoft, Suffolk NR33 0HT, UK e-mail: suzanne.painting@cefas.co.uk

Development of indicators of ecosystem functioning in a temperate shelf sea: a combined fieldwork and modelling approach

A conceptual model of the main carbon and nitrogen flows through pelagic and benthic food webs was used to identify the key biogeochemical processes representing ecosystem functioning, and to select indicators of each of these processes. A combined fieldwork and modelling approach was used to provide the data required to evaluate the indicators in terms of their suitability for assessing and managing the impacts of climate change and demersal trawling. Four of our 16 proposed indicators (phytoplankton production and productivity, near-bed oxygen concentrations and oxygen penetration of the seabed) met the majority of criteria we used for evaluating indicators. Five indicators (depth of anoxic sediment, zoobenthos biomass, production, productivity and bioturbation potential) did not comply with sufficient criteria to be considered as good indicators. Six of our proposed indicators (zooplankton biomass, size structure, production and productivity; ecosystem productivity; ecosystem balance) could not be assessed for sensitivity and specificity using our models, and therefore need to be addressed in future work aimed at improving both the models and the fieldwork. Our results indicate that evaluation of indicators is difficult, because of the number and variety of human pressures which need to be considered in reality, and the interactions between these pressures and the ecosystem components which they affect. The challenge will be to establish if there are indeed any indicators which are able to meet the majority of criteria for good indicators in holistic ecosystem-based assessments.

Ten Thousand Voices on Marine Climate Change in Europe: Different Perceptions among Demographic Groups and Nationalities

Over the past few decades, substantial funding has been directed towards improving scientific understanding and management of impacts of climate change in the marine environment. Following concerns that the key messages from these studies were not reaching the public, a comprehensive opinion poll of 10,000 European citizens in 10 countries was conducted to establish levels of awareness, concern, and trust among different demographic groups (by age, gender, proximity to the coast) and nationalities. Citizens exhibited varying levels of self-declared ‘informedness’ and concern. Citizens from Germany, Italy and Spain claimed to be the most informed on marine climate change issues; those from Czech Republic, Netherlands and Estonia claimed to be least informed. Respondents were least aware of ocean acidification and most aware of melting sea ice, pollution and overfishing. Citizens of Italy suggested that they were generally most concerned about marine climate change issues. Respondents from coastal areas claimed to be both more informed and more concerned than those living inland, as did females and older age groups (54-64 years). European citizens obtain information about climate change in the seas and ocean from different sources, particularly television and the internet. Trust in the various media sources varies among countries and demographic groups. Television is trusted most in Estonia, Germany and Ireland and least in France. The internet is trusted most in Italy, Czech Republic and Estonia, but least in France and the United Kingdom. 18-24 year olds are the biggest users of the internet, but trust this source less than older age groups. Academic scientists or those working for environmental NGOs are trusted more than scientists working for government or industry. Citizens from France are more trusting of industry than any other country polled. In terms of policy actions, most respondents highlighted mitigation measures as opposed to local-scale adaptation. Younger participants prioritised actions associated with reducing carbon emissions, whereas older age groups prioritised improving coastal defences. Successful adaptation to the impacts of climate change requires public engagement and support for policy decisions, and the use of different approaches to take account of differences among demographic groups and nationalities.