Ocean acidification impacts on nitrogen fixation in the coastal western Mediterranean Sea

The effects of ocean acidification on nitrogen (N2) fixation rates and on the community composition of N2-fixing microbes (diazotrophs) were examined in coastal waters of the North-Western Mediterranean Sea. Nine experimental mesocosm enclosures of ∼50 m3 each were deployed for 20 days during June-July 2012 in the Bay of Calvi, Corsica, France. Three control mesocosms were maintained under ambient conditions of carbonate chemistry. The remainder were manipulated with CO2 saturated seawater to attain target amendments of pCO2 of 550, 650, 750, 850, 1000 and 1250 μatm. Rates of N2 fixation were elevated up to 10 times relative to control rates (2.00 ± 1.21 nmol L-1d-1) when pCO2 concentrations were >1000 μatm and pHT (total scale) < 7.74. Diazotrophic phylotypes commonly found in oligotrophic marine waters, including the Mediterranean, were not present at the onset of the experiment and therefore, the diazotroph community composition was characterised by amplifying partial nifH genes from the mesocosms. The diazotroph community was comprised primarily of cluster III nifH sequences (which include possible anaerobes), and proteobacterial (α and γ) sequences, in addition to small numbers of filamentous (or pseudo-filamentous) cyanobacterial phylotypes. The implication from this study is that there is some potential for elevated N2 fixation rates in the coastal western Mediterranean before the end of this century as a result of increasing ocean acidification. Observations made of variability in the diazotroph community composition could not be correlated with changes in carbon chemistry, which highlights the complexity of the relationship between ocean acidification and these keystone organisms.

iMarNet: an ocean biogeochemistry model intercomparison project within a common physical ocean modelling framework

Ocean biogeochemistry (OBGC) models span a wide variety of complexities, including highly simplified nutrient-restoring schemes, nutrient–phytoplankton–zooplankton–detritus (NPZD) models that crudely represent the marine biota, models that represent a broader trophic structure by grouping organisms as plankton functional types (PFTs) based on their biogeochemical role (dynamic green ocean models) and ecosystem models that group organisms by ecological function and trait. OBGC models are now integral components of Earth system models (ESMs), but they compete for computing resources with higher resolution dynamical setups and with other components such as atmospheric chemistry and terrestrial vegetation schemes. As such, the choice of OBGC in ESMs needs to balance model complexity and realism alongside relative computing cost. Here we present an intercomparison of six OBGC models that were candidates for implementation within the next UK Earth system model (UKESM1). The models cover a large range of biological complexity (from 7 to 57 tracers) but all include representations of at least the nitrogen, carbon, alkalinity and oxygen cycles. Each OBGC model was coupled to the ocean general circulation model Nucleus for European Modelling of the Ocean (NEMO) and results from physically identical hindcast simulations were compared. Model skill was evaluated for biogeochemical metrics of global-scale bulk properties using conventional statistical techniques. The computing cost of each model was also measured in standardised tests run at two resource levels. No model is shown to consistently outperform all other models across all metrics. Nonetheless, the simpler models are broadly closer to observations across a number of fields and thus offer a high-efficiency option for ESMs that prioritise high-resolution climate dynamics. However, simpler models provide limited insight into more complex marine biogeochemical processes and ecosystem pathways, and a parallel approach of low-resolution climate dynamics and high-complexity biogeochemistry is desirable in order to provide additional insights into biogeochemistry–climate interactions.

Modelling relative motion to facilitate intra-limb coordination

The importance of relative motion information when modelling a novel motor skill was examined. Participants were assigned to one of four groups. Groups 1 and 2 viewed demonstrations of a skilled cricket bowler presented in either video or point light format. Group 3 observed a single point of light pertaining to the wrist of the skilled bowler only. Participants in Group 4 did not receive a demonstration and acted as controls. During 60 acquisition trials, participants in the demonstration groups viewed a model five times before each 10-trial block. Retention was examined the following day. Intra-limb coordination was assessed for the right elbow relative to the wrist in comparison to the model. The demonstration groups showed greater concordance with the model than the control group. However, the wrist group performed less like the model than the point light and video groups, who did not differ from each other. These effects were maintained in retention. Relative motion information aided the acquisition of intra-limb coordination, while making this information more salient (through point lights) provided no additional benefit. The motion of the models bowling arm was replicated more closely than the non-bowling arm, suggesting that information from the end-effector is prioritized during observation for later reproduction.

The area-independent effects of habitat complexity on biodiversity vary between regions.

Potential explanatory variables often co-vary in studies of species richness. Where topography varies within a survey it is difficult to separate area and habitat-diversity effects. Topographically complex surfaces may contain more species due to increased habitat diversity or as a result of increased area per se. Fractal geometry can be used to adjust species richness estimates to control for increases in area on complex surfaces. Application of fractal techniques to a survey of rocky shores demonstrated an unambiguous area-independent effect of topography on species richness in the Isle of Man. In contrast, variation in species richness in south-west England reflected surface availability alone. Multivariate tests and variation in limpet abundances also demonstrated regional variation in the area-independent effects of topography. Community composition did not vary with increasing surface complexity in south-west England. These results suggest large-scale gradients in the effects of heterogeneity on community processes or demography.

Performance Management in the UK Public Sector: addressing multiple stakeholder complexity

Purpose The aim of this paper is to explore the issues involved in developing and applying performance management approaches within a large UK public sector department using a multiple stakeholder perspective and an accompanying theoretical framework. Design/methodology/approach An initial short questionnaire was used to determine perceptions about the implementation and effectiveness of the new performance management system across the organisation. In total, 700 questionnaires were distributed. Running concurrently with an ethnographic approach, and informed by the questionnaire responses, was a series of semi-structured interviews and focus groups. Findings Staff at all levels had an understanding of the new system and perceived it as being beneficial. However, there were concerns that the approach was not continuously managed throughout the year and was in danger of becoming an annual event, rather than an ongoing process. Furthermore, the change process seemed to have advanced without corresponding changes to appraisal and reward and recognition systems. Thus, the business objectives were not aligned with motivating factors within the organisation. Research limitations/implications Additional research to test the validity and usefulness of the theoretical model, as discussed in this paper, would be beneficial. Practical implications The strategic integration of the stakeholder performance measures and scorecards was found to be essential to producing an overall stakeholder-driven strategy within the case study organisation. Originality/value This paper discusses in detail the approach adopted and the progress made by one large UK public sector organisation, as it attempts to develop better relationships with all of its stakeholders and hence improve its performance. This paper provides a concerted attempt to link theory with practice.

Graded Relative Evidence

Relative Evidential Supports (RES) was developed and justified several years ago as a non-numeric apparatus that allows us to compare evidential supports for alternative conclusions when making a decision. An extension called Graded Relative Evidence (GRE) of the RES concept of pairwise balancing and trading-off of evidence is reported here which keeps its basic features of simplicity and perspicacity but enriches its modelling fidelity by permitting very modest and intuitive variations in degrees of outweighing (which the essentially binary RES does not). The formal justification is very simply based on linkages to RES and to the Dempster - Shafer theory of evidence. The use of the simple extension is illustrated and to a small degree further justified empirically by application to a topical scientific debate about what is called the Congo Crossover Conjecture here. This decision-making instance is chosen because of the wealth of evidence that has been accumulated on both sides of the debate and the range of evidence strengths manifested in it. The conjecture is that the advent of Aids was in the late 1950s in the Congo when a vaccine for polio was allegedly cultivated in the kidneys of chimpanzees which allowed the Aids infection to cross over to humans from primates. © 2005 Springer.