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The relative contribution of endosymbiosis and filter-feeding to

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					Using DEB models to estimate the relative contribution of endosymbiosis

and filter-feeding to the nutrition of different Bathymodiolus azoricus size-

classes



Irene Martins1 , Ana Colaço2 , Paul R. Dando3, João Carlos Marques1, Ricardo Serrão

Santos2, Daniel Desbruyères4



   1- IMAR- Institute of Marine Research, Coimbra Interdisciplinary Centre,

       Department of Zoology, University of Coimbra, 3004-517 Coimbra, Portugal

   2- IMAR- Institute of Marine Research, Department of Oceanography and

       Fisheries, University of the Azores, Cais de Sta Cruz, 9901-862 Horta, Portugal

   3- Marine Biological Association of the UK, Citadel Hill, Plymouth PL12PB, UK

   4- IFREMER, Centre de Brest, Dep. DEEP/LEP, BP70 29280 Plouzané, France



   Dynamic energy budget (DEB) models describing the flux of energy through B.

   azoricus and its endosymbionts were developed for four different size-classes, in

   accordance with individuals collected from the Menez Gwen vent site (Mid-Atlantic

   Ridge). Bathymodiolus azoricus is a mixotrophic mussel, which obtains energy from

   a dual endosymbiosis and filter-feeding. The factors that control the endosymbiosis :

   filter-feeding ratio in B. azoricus   are unclear. We have used DEB models to

   quantify this ratio in different size classes of B. azoricus from the Menez Gwen vent

   site. The model describes the capture of H 2S, CH4 and POC by B. azoricus, the

   microbial oxidations by thiotrophs and methanotrophs at the mussel’s gills, the

   transfer of energy from endosymbionts to B. azoricus and the energetic wastes of B.

   azoricus. In accordance to experimental evidence, the mussel’s clearance rate and
respiration, as well as the uptake of H 2 S and CH4 by endosymbionts were described

by size-dependent relationships. Simulations indicate that the relative contribution

of endosymbiosis to nutrition increases with body size, suggesting that small

individuals have a higher dependency on filter-feeding than large individuals. The

results are discussed and related to the spatial organization of B. azoricus

populations within mussel beds at vent sites.



Contact Information: imartins@ci.uc.pt

				
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posted:3/16/2010
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