Jacques Grall

Human activities and climate variability drive fast-paced change across the world's estuarine-coastal ecosystems

Time series of environmental measurements are essential for detecting, measuring and understanding changes in the Earth system and its biological communities. Observational series have accumulated over the past 2-5 decades from measurements across the worlds estuaries, bays, lagoons, inland seas and shelf waters influenced by runoff. We synthesize information contained in these time series to develop a global view of changes occurring in marine systems influenced by connectivity to land. Our review is organized around four themes: (i) human activities as drivers of change; (ii) variability of the climate system as a driver of change; (iii) successes, disappointments and challenges of managing change at the sea-land interface; and (iv) discoveries made from observations over time. Multidecadal time series reveal that many of the worlds estuarine-coastal ecosystems are in a continuing state of change, and the pace of change is faster than we could have imagined a decade ago. Some have been transformed into novel ecosystems with habitats, biogeochemistry and biological communities outside the natural range of variability. Change takes many forms including linear and nonlinear trends, abrupt state changes and oscillations. The challenge of managing change is daunting in the coastal zone where diverse human pressures are concentrated and intersect with different responses to climate variability over land and over ocean basins. The pace of change in estuarine-coastal ecosystems will likely accelerate as the human population and economies continue to grow and as global climate change accelerates. Wise stewardship of the resources upon which we depend is critically dependent upon a continuing flow of information from observations to measure, understand and anticipate future changes along the worlds coastlines.

The Impossible Sustainability of the Bay of Brest? Fifty Years of Ecosystem Changes, Interdisciplinary Knowledge Construction and Key Questions at the Science-Policy-Community Interface

In this contribution, the study of the Bay of Brest ecosystem changes over the past 50 years is used to explore the construction of interdisciplinary knowledge and raise key questions that now need to be tackled at the science-policy-communities interface. The Bay of Brest is subject to a combination of several aspects of global change, including excessive nutrient inputs from watersheds and the proliferation of invasive species. These perturbations strongly interact, affecting positively or negatively the ecosystem functioning, with important impacts on human activities. We first relate a cascade of events over these five decades, linking farming activities, nitrogen and silicon biogeochemical cycles, hydrodynamics of the Bay, the proliferation of an exotic benthic suspension feeder, the development of the Great scallop fisheries and the high biodiversity in maerl beds. The cascade leads to today’s situation where toxic phytoplankton blooms become recurrent in the Bay, preventing the fishery of the great scallop and forcing the fishermen community to switch pray and alter the maerl habitat and the benthic biodiversity it hosts, despite the many scientific alerts and the protection of this habitat. In the second section, we relate the construction of the interdisciplinary knowledge without which scientists would never have been able to describe these changes in the Bay. Interdisciplinarity, first among natural sciences (NS) and then, between natural sciences and human and social sciences (HSS). We finally ask key questions at the science-policy interface regarding this unsustainable trend of the Bay: How is this possible, despite decades of joint work between scientists and fishermen? Is adaptive co-management a sufficient condition for a sustainable management of an ecosystem? How do the different groups (i.e. farmers, fishermen, scientists, environmentalists), with their diverse interests, take charge of this situation? What is the role of power in this difficult transformation to sustainability? Combining natural sciences with political science, anthropology and the political sociology of science, we hope to improve the contribution of HSS to integrated studies of social-ecological systems, creating the conditions to address these key questions at the science-policy interface to facilitate the transformation of the Bay of Brest ecosystem towards sustainability.

Preface--Contributions to the 8th International Conference on Applications of Stable Isotope Techniques to Ecological Studies (ISOECOL), Brest, France, 20-24 August 2012.

The 8th International Conference on Applications of Stable Isotope Techniques to Ecological Studies (aka ISOECOL) was held in Brest (Brittany, France) in August 2012. A total of 252 researchers from 37 countries attended this meeting, and 221 papers were presented. ISOECOL conferences have been growing fast since their first edition in 1998 (Saskatoon, Canada). A friendly and collaborative atmosphere sets ISOECOL conferences apart, gathering ecologists from a large diversity of fields around a common tool: stable isotopes. One – if not the main – force of ISOECOL meetings is to bring together all scientists in a single conference room, hence broadening the perspectives of the whole audience, forcing scientists to open their minds to other fields, different biological models, new or improved isotopic tools or techniques and ultimately facilitating fruitful dialogues. As the ISOECOL group is growing, it is also challenging to keep this spirit – initiated by Keith Hobson and Leonard Wassenaar – alive. At this point we would like to thank Brian Fry (Griffith University) for having set the tone (literally!) of this conference: not only have all participants had the chance to listen to Brian play the isotopic organ (who knew there was an isotopic song?) but we can now all follow and support the goofy mascot Orbit and the Isotopic Albuquerque baseball team. There is no doubt that Brian’s version of isotopic ecology history was the perfect kick-off talk. It is probably now an understatement to state that ‘the field of stable isotope techniques has expanded tremendously’ or that ‘stable isotope analyses have increasingly been used and are a powerful tool to address ecological questions relative to animal feeding ecology and migration patterns’. Ben Parker once said: ‘With great power comes great responsibility’ [1]. This applies to isotopes as well. This conference was an opportunity to address hot isotope topics, which commonly (but often temporarily) change iso-euphoric persons, thus opening Pandora’s box to iso-skeptics discovering Tantalus’ punishment. Initiated by Kirsteen MacKenzie and Clive Trueman (University of Southampton), a pre-conference workshop was fully dedicated to the common pitfalls isotopic ecologists are tackling while building their protocols or sampling all kinds of animal tissues. This workshop set the scene for numerous talks and posters. For example, a full session was dedicated to discrimination factors in isotopes, revealing – if necessary – the need to understand isotopic fractionation processes at all levels (molecular, tissue, organism, etc.) and above all the need to assess the consequences of what we do not understand. Similarly, isotopic routing and tissue turnover often remain black boxes in biological models. Sebastien Lefebvre’s (University of Lille) keynote reviewed physiology models and broad dynamic energy budget models put into perspective with isotopic routing, opening a new field of investigation in isotopic ecology. The common issue of solving isotope mixtures with mathematical models was