Deep-water sediment transport patterns and basin floor topography in early rift basins: Plio-Pleistocene syn-rift of the Corinth Rift,Greece

Our current understanding on sedimentary deep-water environments is mainly built of information obtained from tectonic settings such as passive margins and foreland basins. More observations from extensional settings are particularly needed in order to better constrain the role of active tectonics in controlling sediment pathways, depositional style and stratigraphic stacking patterns. This study focuses on the evolution of a Plio-Pleistocene deep-water sedimentary system (Rethi-Dendro Formation) and its relation to structural activity in the Amphithea fault block in the Corinth Rift, Greece. The Corinth Rift is an active extensional basin in the early stages of rift evolution, providing perfect opportunities for the study of early deep-water syn-rift deposits that are usually eroded from the rift shoulders due to erosion in mature basins like the Red Sea, North Sea and the Atlantic rifted margin. The depocentre is located at the exit of a structurally controlled sediment fairway, approximately 15 km from its main sediment source and 12 km basinwards from the basin margin coastline. Fieldwork, augmented by digital outcrop techniques (LiDAR and photogrammetry) and clast-count compositional analysis allowed identification of 16 stratigraphic units that are grouped into six types of depositional elements: A—mudstone-dominated sheets, B—conglomerate-dominated lobes, C—conglomerate channel belts and sandstone sheets, D—sandstone channel belts, E—sandstone-dominated broad shallow lobes, F—sandstone-dominated sheets with broad shallow channels. The formation represents an axial system sourced by a hinterland-fed Mavro delta, with minor contributions from a transverse system of conglomerate-dominated lobes sourced from intrabasinal highs. The results of clast compositional analysis enable precise attribution for the different sediment sources to the deep-water system and their link to other stratigraphic units in the area. Structures in the Amphithea fault block played a major role in controlling the location and orientation of sedimentary systems by modifying basin-floor gradients due to a combination of hangingwall tilt, displacement of faults internal to the depocentre and folding on top of blind growing faults. Fault activity also promoted large-scale subaqueous landslides and eventual uplift of the whole fault block.     

The dynamism of clustering: Interweaving material and discursive processes

The aim of this paper is to contribute to an understanding of clusters, including both the material and discursive dynamism of cluster construction, and shed light on how clusters—once established—affect the actors, institutions and processes that constitute them. It does this by viewing clusters as an actant, i.e. something that acts or to which activity is granted by others. The empirical analysis examines two clusters in the public cluster programme Norwegian Centre of Expertise (NCE): the Møre maritime cluster and the Hordaland subsea cluster. It focuses on the type of development paths they are following and how the material and discursive processes are interweaved in these paths. The clusters are related to the concept of cluster construction, which is triggered by ideas, representations, policy and industry practice. The Møre maritime cluster is characterized by bottom-up clustering processes and illustrates how the material practices of firms can trigger clustering processes such as the establishment of a cluster and the identification of a prototype of best cluster practice. On the other hand, the Hordaland subsea cluster expresses a top-down process and how the ideal world of academics and policy-making can encourage processes of clustering among co-located firms. Based on these observations of material and discursive interweaved clustering processes and how they affect both those who are practicing and those who are promoting them, we find it reasonable to argue for a stronger awareness of such feedback loops in cluster studies.     

The Charney-Stern theorem on barotropic-baroclinic instability

The Rayleigh stability criterion for linear, incompressible and inviscid flow, of which the Charney-Stern theorem is a generalization, is reviewed together with Fjørtoft’s theorem. The linear equations governing small-amplitude adiabatic disturbances superimposed on a baroclinic zonal current in a beta-plane channel are expressed in isentropic coordinates. Using an integral constraint technique introduced by G. I. Taylor, and introducing geostrophy by assuming smallness of the particle frequency, it is shown that the Charney-Stern theorem follows without making any further assumptions.     

Fishing‐induced evolution of growth: concepts,mechanisms and the empirical evidence

The interest in fishing‐induced life‐history evolution has been growing in the last decade, in part because of the increasing number of studies suggesting evolutionary changes in life‐history traits, and the potential ecological and economic consequences these changes may have. Among the traits that could evolve in response to fishing, growth has lately received attention. However, critical reading of the literature on growth evolution in fish reveals conceptual confusion about the nature of ‘growth’ itself as an evolving trait, and about the different ways fishing can affect growth and size‐at‐age of fish, both on ecological and on evolutionary time‐scales. It is important to separate the advantages of being big and the costs of growing to a large size, particularly when studying life‐history evolution. In this review, we explore the selection pressures on growth and the resultant evolution of growth from a mechanistic viewpoint. We define important concepts and outline the processes that must be accounted for before observed phenotypic changes can be ascribed to growth evolution. When listing traits that could be traded‐off with growth rate, we group the mechanisms into those affecting resource acquisition and those governing resource allocation. We summarize potential effects of fishing on traits related to growth and discuss methods for detecting evolution of growth. We also challenge the prevailing expectation that fishing‐induced evolution should always lead to slower growth.     

The political ecology of Chilean salmon aquaculture, 1982–2010: A trajectory from economic development to global sustainability

Through the case of the salmon aquaculture sector in Chile, the risks involved in the development of a non-traditional export sector are reviewed, in order to point to failings (lessons not learned) and opportunities (lessons learned, new plans), and the changing scales of stakeholder interactions. In particular the paper highlights the ways in which sustainability considerations have gained ground in terms of evaluating sectoral development and what is expected from this development. These considerations have emerged as a result of the increasing globalisation of the sector, through investment, exports and international ‘attention’ from an increasingly diverse set of stakeholders. These sustainability considerations have generated a range of conflicts linked to these diverse actors. The actors are local, national and global, operating through alliances to bring pressure on others. The conflicts relate to environmental quality, foreign direct investment (FDI), local socio-economic development, regional development, national economic strategies, and new globalised issues relating to the production and consumption of foodstuffs. The contemporary panorama in the sector is significantly different from the early origins in the 1980s under the dictatorship – the period of ‘the socio-ecological silence’ – also different from the 1990s period of economic expansion – ‘the economic imperative’. Over the past twenty-five years, the Chilean aquaculture sector has evolved from experimental production to a major global industry. Regulatory frameworks and civil society awareness and mobilisation have struggled to ‘catch up’ with the dynamism of the sector, however the gap has reduced and the future of the sector within the contemporary context of ‘glocal’ sustainability is now under the microscope: the ‘sustainable globalisation perspective’. The collapse of the sector during the period 2008–2010 as a consequence of the ISA virus is a key moment with production severely diminished. The way out of the crisis, via new legislation and inspection regimes, will create a new structure of aquaculture governance. Nevertheless, the crisis marks a turning point in the industry, revealing the weaknesses built into the former productive system.