Interaction Effects of Light, Temperature and Nutrient Limitations (N, P and Si) on Growth, Stoichiometry and Photosynthetic Parameters of the Cold-Water Diatom Chaetoceros wighamii

Light (20-450 mu mol photons m(-2) s(-1)), temperature (3-11 degrees C) and inorganic nutrient composition (nutrient replete and N, P and Si limitation) were manipulated to study their combined influence on growth, stoichiometry (C:N:P:Chl a) and primary production of the cold water diatom Chaetoceros wighamii. During exponential growth, the maximum growth rate (similar to 0.8 d(-1)) was observed at high temperture and light; at 3 degrees C the growth rate was similar to 30% lower under similar light conditions. The interaction effect of light and temperature were clearly visible from growth and cellular stoichiometry. The average C:N:P molar ratio was 80:13:1 during exponential growth, but the range, due to different light acclimation, was widest at the lowest temperature, reaching very low C:P (similar to 50) and N:P ratios (similar to 8) at low light and temperature. The C:Chl a ratio had also a wider range at the lowest temperature during exponential growth, ranging 16-48 (weight ratio) at 3 degrees C compared with 17-33 at 11 degrees C. During exponential growth, there was no clear trend in the Chl a normalized, initial slope (alpha*) of the photosynthesis-irradiance (PE) curve, but the maximum photosynthetic production (P-m) was highest for cultures acclimated to the highest light and temperature. During the stationary growth phase, the stoichiometric relationship depended on the limiting nutrient, but with generally increasing C:N:P ratio. The average photosynthetic quotient (PQ) during exponential growth was 1.26 but decreased toPeer reviewe

Landscape structure, human disturbance and crop management affect foraging ground selection by migrating geese

It is well known that agricultural intensification has caused severe population declines among bird species which use farmland for breeding and overwintering, while migrating bird species may benefit from intensive farming, but in turn damage crops. Knowledge of the habitat selection of migrating birds is important from both a conservation and agro-economic point of view. We investigated the habitat preferences of three common migrating goose species: White-fronted Goose Anser albifrons, Bean Goose A. fabalis and Greylag Goose A. anser during the autumn of 2009 in western Poland. A total of 24 flocks of these species were identified. Geese preferred large, elevated fields that were remote from forests and human settlements but in close proximity to a lake. Geese selected maize stubbles and avoided winter cereals. They selected sites in landscapes with a lower diversity of crops. Flock size was negatively correlated with the proportion of pastures in the landscape, but it increased with field size, distance to forest and distance to town. Our results are in contrast with the paradigm that less intensive farmland positively influences habitat use by birds during foraging. We advise the delayed ploughing of stubbles with the aim of creating appropriate foraging habitats for geese and minimizing damage to cereal crops

Looking inside the spiky bits : a critical review and conceptualisation of entrepreneurial ecosystems

The authors wish to thank the Organisational for Economic Cooperation and Development (OECD) for funding their original research on entrepreneurial ecosystems.The concept of entrepreneurial ecosystems has quickly established itself as one of the latest ‘fads’ in entrepreneurship research. At face value, this kind of systemic approach to entrepreneurship offers a new and distinctive path for scholars and policy makers to help understand and foster growth-oriented entrepreneurship. However, its lack of specification and conceptual limitations has undoubtedly hindered our understanding of these complex organisms. Indeed, the rapid adoption of the concept has tended to overlook the heterogeneous nature of ecosystems. This paper provides a critical review and conceptualisation of the ecosystems concept: it unpacks the dynamics of the concept; outlines its theoretical limitations; measurement approaches and use in policy-making. It sets out a preliminary taxonomy of different archetypal ecosystems. The paper concludes that entrepreneurial ecosystems are a highly variegated, multi-actor and multi-scalar phenomenon, requiring bespoke policy interventions.Publisher PDFPeer reviewe

An Overview of Manifold and its Implementation

this paper we introduce MANIFOLD