InterRidge is an international and interdisciplinary initiative concerned with all aspects of mid-ocean ridges. It is designed to encourage scientific and logistical coordination, with particular focus on problems that cannot be addressed as efficiently by nations acting alone or in limited partnerships. Its activities range from dissemination of information on existing, single- institution experiments to initiation of fully multi-national projects.
(c) InterRidge 2002
Since 2002, the first of January, AUSTRIA is a corresponding member of Inter Ridge!
The Austrian InterRidge Correspondent is Monika Bright
Austrian biological research at the hydrothermal vents is concentrated for the most part on chemoautotrophic sulfur-oxidizing (thiotrophic) symbioses. The most relevant of our studies to InterRidge are those focusing on Riftia pachyptila (Vestimentifera), one of the most conspicuous and well-studied of thiotrophic symbioses from the East Pacific Rise, Galapagos Rift and Guyamas Basin. Similar to many invertebrates, the worm's life cycle is characterized by a pelagic larva and a benthic adult. These two phases are linked by a settlement event that triggers a major morphological transformation during metamorphosis. In Riftia pachyptila, this life cycle is additionally impacted by another event - the uptake of the specific symbiont in the early juvenile phase that triggers a transformation from a non-symbiotic, heterotrophic animal and a free-living, autotrophic microbe to a 'symbiotic entity' (Fig. 1). This process builds the framework of our studies in which we attempt to directly follow adaptations and study interactions in order to gain insight in the evolution of this association.
In the past years we concentrated on nutritional interactions and studied some aspects of the carbon metabolism in Riftia pachyptila symbiosis. By pulse-chase experiments in high-pressure aquaria and calculations of carbon incorportion rates using 14C bicarbonate autoradiography and of carbon storage rates by quantitative electron microscopy we found that translocation of organic carbon from the symbionts to the host is a very fast process and is mainly facilitated by release of low molecular weight products. The single microbial symbiont, morphologically variable in size and form, was found to behave physiologically different in respect to carbon incorporation and storage according to its morphotypes (Bright et al., 2000, Sorgo et al., in press). These morphotypes are hypothesized to represent different stages in a complex microbial life and terminal differentiation cycle that might be an adaptive strategy to an endosymbiotic life style (Bright & Sorgo, in press). Ongoing research focuses on the morphological and ultrastructural adaptations during the life cycle of the host from early non-symbiotic, sessile stages in the size rage of 250 µm to a symbiotic later stage already developed in 150 µm larger individuals. We are especially interested in the time frame and location as well as specificity of symbiont uptake.
This research at the East Pacific Rise has been made possible by extensive cooperations with USA (C.R. Fisher, H. Felbeck, L. Mullineaux, J.J. Childress) and France (F. Gaill), and fundings from the Austrian Science Foundations (FWF H0087-BIO, P13762-BIO). Participation on several cruises during the last years, where collections of animals and experiments could be carried out, are greatly acknowledged. Currently, we are invited by C.R. Fisher to join a cruise to the East Pacific Rise in December, 2001 in order to continue our studies.
We would like to build a platform of Austrian scientists in order to unite researchers in any discipline of natural science involving ridge-crest studies for exchange and cooperations within Austria and with other members of InterRidge. We anticipate to strengthen our presence in the Austrian as well as international scientific community and become an active member in InterRidge. We would like to take this opportunity to invite Austrian scientists to contact us for more information:
Monika Bright Marine Biology Institute of Ecology and Conservation Biology University of Vienna Althanstr. 14 A-1090 Vienna Austria
phone + 43-1-4277-54331 fax: + 43-1-4277-9542
References Bright M., Keckeis H., and Fisher C.R. An autoradiographic examination of carbon fixation, transfer, and utilization in the Riftia pachyptila symbiosis. Mar Biol, 136, 621-632, 2000.
Bright M. and Sorgo A. Ultrastructural reinvestigation of the trophosome in adult Riftia pachyptila (Vestimentifera). Inv Biol., in press.
Sorgo A., Gaill F., Lechaire J.-P., Arndt C., Bright M. Glycogen storage in the Riftia pachyptila trophosome: contribution of host and symbionts. MEPS, 231, 115-120, 2002
InterRidge 
