985 resultados para Aquatic communities


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Collaborative approaches in leadership and management are increasingly acknowledged to play a key role in successful institutions in the learning and skills sector (LSS) (Ofsted, 2004). Such approaches may be important in bridging the potential 'distance' (psychological, cultural, interactional and geographical) (Collinson, 2005) that may exist between 'leaders' and 'followers', fostering more democratic communal solidarity. This paper reports on a 2006-07 research project funded by the Centre for Excellence in Leadership (CEL) that aimed to collect and analyse data on 'collaborative leadership' (CL) in the learning and skills sector. The project investigated collaborative leadership and its potential for benefiting staff through trust and knowledge-sharing in communities of practice (CoPs). The project forms part of longer-term educational research investigating leadership in a collaborative inquiry process (Jameson et al., 2006). The research examined the potential for CL to benefit institutions, analysing respondents' understanding of and resistance to collaborative practices. Quantitative and qualitative data from senior managers and lecturers was analysed using electronic data in SPSS and Tropes Zoom. The project aimed to recommend systems and practices for more inclusive, diverse leadership (Lumby et al., 2005). Collaborative leadership has increasingly gained international prominence as emphasis shifted towards team leadership beyond zero-sum 'leadership'/ 'followership' polarities into more mature conceptions of shared leadership spaces, within which synergistic leadership spaces can be mediated. The relevance of collaboration within the LSS has been highlighted following a spate of recent government-driven policy developments in FE. The promotion of CL addresses concerns about the apparent 'remoteness' of some senior managers, and the 'neo-management' control of professionals which can increase 'distance' between leaders and 'followers' and may de-professionalise staff in an already disempowered sector. Positive benefit from 'collaborative advantage' tends to be assumed in idealistic interpretations of CL, but potential 'collaborative inertia' may be problematic in a sector characterised by rapid top-down policy changes and continuous external audit and surveillance. Constant pressure for achievement against goals leaves little time for democratic group negotiations, despite the desires of leaders to create a more collaborative ethos. Yet prior models of intentional communities of practice potentially offer promise for CL practice to improve group performance despite multiple constraints. The CAMEL CoP model (JISC infoNet, 2006) was linked to the project, providing one practical way of implementing CL within situated professional networks.The project found that a good understanding of CL was demonstrated by most respondents, who thought it could enable staff to share power and work in partnership to build trust and conjoin skills, abilities and experience to achieve common goals for the good of the sector. However, although most respondents expressed agreement with the concept and ideals of CL, many thought this was currently an idealistically democratic, unachievable pipe dream in the LSS. Many respondents expressed concerns with the 'audit culture' and authoritarian management structures in FE. While there was a strong desire to see greater levels of implementation of CL, and 'collaborative advantage' from the 'knowledge sharing benefit potential' of team leadership, respondents also strongly advised against the pitfalls of 'collaborative inertia'. A 'distance' between senior leadership views and those of staff lower down the hierarchy regarding aspects of leadership performance in the sector was reported. Finally, the project found that more research is needed to investigate CL and develop innovative methods of practical implementation within autonomous communities of professional practice.

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Nistor, N., Dascalu, M., Stavarache, L.L., Serafin, Y., & Trausan-Matu, S. (2015). Informal Learning in Online Knowledge Communities: Predicting Community Response to Visitor Inquiries. In G. Conole, T. Klobucar, C. Rensing, J. Konert & É. Lavoué (Eds.), 10th European Conf. on Technology Enhanced Learning (pp. 447–452). Toledo, Spain: Springer.

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Nistor, N., Dascalu, M., Stavarache, L.L., Tarnai, C., & Trausan-Matu, S. (2015). Predicting Newcomer Integration in Online Knowledge Communities by Automated Dialog Analysis. In Y. Li, M. Chang, M. Kravcik, E. Popescu, R. Huang, Kinshuk & N.-S. Chen (Eds.), State-of-the-Art and Future Directions of Smart Learning (Vol. Lecture Notes in Educational Technology, pp. 13–17). Berlin, Germany: Springer-Verlag Singapur

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This review provides insights into the distribution and impact of oestrogens and xeno-oestrogens in the aquatic environment and highlights some significant knowledge gaps in our understanding of endocrine disrupting chemicals. Key areas of uncertainty in the assessment of risk include the role of estuarine sediments in mediating the fate and bioavailability of environmental (xeno)oestrogens (notably their transfer to benthic organisms and estuarine food chains), together with evidence for endocrine disruption in invertebrate populations. Emphasis is placed on using published information to interpret the behaviour and effects of a small number of model compounds thought to contribute to oestrogenic effects in nature; namely, the natural steroid 17 beta -oestradiol (E2) and the synthetic hormone 17 alpha -ethinyloestradiol (EE2), together with the alkyl-phenols octyl- and nonyl-phenol (OP, NP) as oestrogen mimics. Individual sections of the review are devoted to sources and concentrations of (xeno)oestrogens in waterways, sediment partitioning and persistence, bioaccumulation rates and routes, assays and biomarkers of oestrogenicity, and, finally, a synopsis of reproductive and ecological effects in aquatic species.

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The effect of elevated pCO(2)/low pH on marine invertebrate benthic biodiversity, community structure and selected functional responses which underpin ecosystem services (such as community production and calcification) was tested in a medium-term (30 days) mesocosm experiment in June 2010. Standardised intertidal macrobenthic communities, collected (50.3567A degrees N, 4.1277A degrees W) using artificial substrate units (ASUs), were exposed to one of seven pH treatments (8.05, 7.8. 7.6, 7.4, 7.2, 6.8 and 6.0). Community net calcification/dissolution rates, as well as changes in biomass, community structure and diversity, were measured at the end of the experimental period. Communities showed significant changes in structure and reduced diversity in response to reduced pH: shifting from a community dominated by calcareous organisms to one dominated by non-calcareous organisms around either pH 7.2 (number of individuals and species) or pH 7.8 (biomass). These results were supported by a reduced total weight of CaCO3 structures in all major taxa at lowered pH and a switch from net calcification to net dissolution around pH 7.4 (a"broken vertical bar(calc) = 0.78, a"broken vertical bar(ara) = 0.5). Overall community soft tissue biomass did not change with pH and high mortality was observed only at pH 6.0, although molluscs and arthropods showed significant decreases in soft tissue. This study supports and refines previous findings on how elevated pCO(2) can induce changes in marine biodiversity, underlined by differential vulnerability of different phyla. In addition, it shows significant elevated pCO(2)-/low pH-dependent changes in fundamental community functional responses underpinning changes in ecosystem services.

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Variations in the concentrations and microheterotrophic degradation rates of selected Polycyclic Aromatic Hydrocarbons (PAH) in the water column of the Tamar Estuary were investigated in relation to the major environmental variables. Concentrations of individual PAH varied typically between i and 50 ng l−1 Based on their observed environmental behaviour the PAH appeared divisible into two groupings: (1) low molecular weight PAH incorporating naphthalene, phenanthrene and anthracence and (a) the larger molecular weight homologues (fluoranthene, pyrene, chrysene, benz(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)-pyrene). Group 1 PAH showed a complex distribution throughout the estuary with no significant correlations with either salinity or suspended particulates. Based on their relatively low particle affinity and high water solubilities and vapour pressures, volatilization is proposed as an important process in determining their fate. Microheterotrophic turnover times of naphthalene varied between x and 30 days, and were independent of suspended solids with maximum degradation rates located in the central and urban regions of the Estuary. When compared with the flushing times for the Tamar (3–5 days), it is probable that heterotrophic activity is important in the removal of naphthalene (and possibly the other Group 1 PAH) from the estuarine environment. In contrast Group 2 PAH concentrations exhibited highly significant correlations with suspended particulates. Highest concentrations occurred at the turbidity maximum, with a secondary concentration maximum localized to the industrialized portion of the estuary and associated with anthropogenic inputs. Laboratory degradation studies of benzo(a)pyrene in water samples taken from the estuary showed turnover times for the compound of between 2000 and 9000 days. Degradation rates correlated positively with suspended solids. The high particulate affinity and microbial refractivity of Group 2 PAH indicate sediment burial as the principal tate of these PAH in the Tamar Estuary. Estuarine sediments contained typically 50–1500 ng g−1 dry weight of individual PAH which were comparable to the levels of Group 2 PAH associated with the suspended particulates. Highest concentrations occurred at the riverine end of the estuary resulting from unresolved inputs in the catchment. Subsequent dilution by less polluted marine sediments together with slow degradation results in a seaward trend of decreasing concentrations. However, there is a secondary maximum of PAH superimposed on this trend which is associated with urban Plymouth.

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The way in which total secondary production is partitioned amongst species in various macrofauna communities (Amphiura, Venus, Abra, Modiolus) around the British Isles is discussed. When the proportion of total production is plotted for each species, ranked in order of productive importance, curves are produced which are characteristic of particular physical conditions. The shapes of the curves are independent of the actual species involved, but depend on the proportion of individuals in the community which adopt a particular feeding behaviour, and the scope for diversification within trophic groups. The form of these curves correlates closely with bottom currents and associated bed-stresses, since these affect both the nature of the food supply to bottom animals and the nature of the substrate. These observations have important implications for the structure and functioning of benthic communities. Comparison of production partitioning in the meiofauna of mud and sand substrates indicates a remarkable similarity within trophic groups although the partitioning of production between trophic groups is very different. The shapes of production-rank curves again appear to depend on the scope for diversification within trophic groups. In the meiofauna resources are partitioned more equitably than in the macrofauna. There is a marked discontinuity in the lognormal distribution of body sizes within integrated benthic communities at the meiofauna-macrofauna size boundary.