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FortHjort Seminar - Interdisciplinary studies 1

Time: 2014.05.22 14:15 - 15:15
Location: K1/K2, BIO (A-blokken), University of Bergen, Thormølensgate 53

Speakers: Selina Våge (UiB), Audrey J. Geffen (UiB) and Svein Sundby (IMR)

Selina Våge (UiB)
Trade-offs between competition and viral defense structure pelagic prokaryote communities

Abstract:
While metagenome analyses rapidly increase our knowledge of an enormous biodiversity among pelagic prokaryotes and their associated viruses, the conceptual framework of how this diversity is generated and how microbial food web structures are maintained remains poorly developed. Bacteria, having to reproduce within the order of a day before either being eaten or killed by lytic viruses, undergo a strong selection pressure. Successful strategies must therefore be finely balanced between sufficient competitiveness and defensiveness. We present a theoretical framework that incorporates a trade-off between competition and defense in a virus-host system, thus offering an alternative entrance to the classical 'dead or dormant' debate of why there seems to be so many low-active prokaryotes in the ocean. We show how the framework may explain much of the structuring and biodiversity found in pelagic microbial communities. In particular, we use our model to provide an explanation for why the highly abundant SAR11 bacteria may be so successful in the pelagic ecosystem. Understanding the success of specific bacterial groups is important for understanding ecosystem functioning and biogeochemical cycling.

 

Audrey J. Geffen (UiB)
Connectivity and its implications towards conservation and management

Abstract:
Connectivity is a term used widely in ecology, conservation, and resource management communication - in terrestrial and aquatic ecosystems.  Although the same word is used in many different contexts its meaning can be very different, and this is a particularly challenging situation for communication between scientists, managers, and policy makers. Whereas terrestrial ecologists focus on connectivity as an attribute of the landscape or physical system, marine ecologists have focussed on connectivity as an attribute of populations. A long range dispersal stage is nearly ubiquitous in marine organisms and the links between the various life history stages, or component populations, are large-scale features of the climate and ocean system. Anthropogenic activities are major disruptors of "life history closure", as seen in classic examples where spawning migrations are disrupted by construction projects. Spatial management decisions which seek to protect specific locations and habitats often claim to rely on science-based evidence of connectivity to justify the importance of an area for a commercially important (fish) population. The spatial and biological concepts of connectivity need reconciliation in the management of physical and biological resources, in order to meet the challenges of shifting population distributions due to ocean warming and climate change.

 

Svein Sundby (IMR)
Regional effects of global climate change - results from the ocean chapters in IPCC-Working Group 2, 5th Assessment Report

Abstract:
The 5th Assessment Report of IPCC Working Group 2 "Impacts, Adaptations, and Vulnerability" (http://www.ipcc-wg2.gov/AR5/) was released in Yokohama, Japan, 31 March 2014. Two of the 30 chapters are considering the impacts on marine ecosystems. Surprisingly, this is the first IPCC Assessment Report that contains dedicated chapters on the world ocean ecosystems. Information about the process of the IPCC work will be given and some highlights from the two ocean chapter will be presented. The Hjort Centre should be prepared to nominate lead authors for the next Assessment Report, which assumedly will be initiated in 2 years time