Bioturbation, the biogenic modification of sediments through particle reworking and burrow ventilation, is a key mediator of many important geochemical processes in marine systems. In situ quantification of bioturbation can be achieved in a myriad of ways, requiring expert knowledge, technology, and resources not always available, and not feasible in some settings. Where dedicated research programmes do not exist, a practical alternative is the adoption of a trait-based approach to estimate community bioturbation potential (BPc). This index can be calculated from inventories of species, abundance and biomass data (routinely available for many systems), and a functional classification of organism traits associated with sediment mixing (less available). Presently, however, there is no agreed standard categorization for the reworking mode and mobility of benthic species. Based on information from the literature and expert opinion, we provide a functional classification for 1033 benthic invertebrate species from the northwest European continental shelf, as a tool to enable the standardized calculation of BPc in the region. Future uses of this classification table will increase the comparability and utility of large-scale assessments of ecosystem processes and functioning influenced by bioturbation (e.g., to support legislation). The key strengths, assumptions, and limitations of BPc as a metric are critically reviewed, offering guidelines for its calculation and application.

A large number of studies have now explicitly examined the relationship between species loss and ecosystem functions. The results from such "biodiversity experiments" have previously been collated and analyzed by two independent groups of authors. Both data sets show that reductions in species diversity generally result in reduced ecosystem functioning, even though the studies cover a wide range of ecosystems, diversity manipulations, and response variables. In this chapter, we analyze the two data sets in parallel to explain variation in the observed functional effects of biodiversity. The main conclusions are: 1) the functional effects of biodiversity differ among ecosystem types (but not between terrestrial and aquatic systems), 2) increases in species richness enhance community responses but negatively affect population responses, 3) stocks are more responsive than rates to biodiversity manipulations, 4) when diversity reductions at one trophic level affect a function at an adjacent trophic level (higher or lower), the function is often reduced 5) increased biodiversity results in increased invasion resistance. We also analyze the shape of the relationship between biodiversity and response variables, and discuss some consequences of different relationships.

Long-term effects of warming and ocean acidification are modified by seasonal variation in species responses and environmental conditions Jasmin A. Godbold and Martin Solan Ocean and Earth Science, National Oceanography Center Southampton, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK Warming of sea surface temperatures and alteration of ocean chemistry associated with anthropogenic increases in atmospheric carbon dioxide will have profound consequences for a broad range of species, but the potential for seasonal variation to modify species and ecosystem responses to these stressors has received little attention. Here, using the longest experiment to date (542 days), we investigate how the interactive effects of warming and ocean acidification affect the growth, behaviour and associated levels of ecosystem functioning (nutrient release) for a functionally important non-calcifying intertidal polychaete (Alitta virens) under seasonally changing conditions. We find that the effects of warming, ocean acidification and their interactions are not detectable in the short term, but manifest over time through changes in growth, bioturbation and bioirrigation behaviour that, in turn, affect nutrient generation. These changes are intimately linked to species responses to seasonal variations in environmental conditions (temperature and photoperiod) that, depending upon timing, can either exacerbate or buffer the long-term directional effects of climatic forcing. Taken together, our observations caution against over emphasizing the conclusions from short-term experiments and highlight the necessity to consider the temporal expression of complex system dynamics established over appropriate timescales when forecasting the likely ecological consequences of climatic forcing. IntroductionSince the industrial revolution, CO 2 emissions from the burning of fossil fuels and changes in land use have steadily increased atmospheric CO 2 concentration from preindustrial levels of 280 ppm to currently approximately 385 ppm; these levels are projected to increase to 700-1000 ppm by the end of the twenty-first century [1], causing concomitant changes in global sea surface temperature (2-4.58C rise [2]) and chemistry (e.g. 0.4 -0.5 pH reduction [2]). Although historical records indicate that atmospheric CO 2 concentrations and sea surface temperatures have undergone significant oscillations and have exceeded present-day levels in the past [3,4], it is the unprecedented rates of change that are fuelling concerns over whether organisms will retain the capacity to mediate vital ecosystem functions and services [5,6]. A key component in answering this question will be a need to establish the likelihood, and realized extent, of species acclimation (or adaptation) to environmental change [7,8] and, if common across functionally important taxa, how such coping and adaptive strategies will alter species -environment interactions in the long term [9].Over the last decade, the impacts of warming and ocean acidif...