Sonja,

That's very interesting.  What is the diet of your worms?  My thoughts are
that -38 per mil is at the extreme low end for modern plants (assumedly what
your worms are eating...please correct me if I'm wrong) of all
photosynthetic pathways.  However, there are some unique food sources on
this planet where d13C can be very depleted.  For example, some types of
bacteria get down to -40 per mil (CH. 27 in Faure and Mensing, 2002,
Isotopes).  Also mentioned in Faure and Mensing, a study by Kaplan and
Nisenbaum (1966, Science, 153: 744-745) found fossil (Pliestocene-age) algal
mats in Israel with d13C values of -82.5 to 89.3 per mil.

Perhaps your worms have an exotic diet...

All the best,
Trevor

Trevor J. Porter, B.Sc. Honours
Ph.D. Candidate
Carleton University Paleoecology Laboratory
Department of Geography and Environmental Studies
1125 Colonel By Drive
Ottawa, Ontario
Canada K1S 5B6
613-520-2600 ext. 1836
http://chat.carleton.ca/~tjporter


Dear all,
we analysed stable C and N isotope compositions of soft tissues of 
serpulide worms from estuarine and marine environments and got some very 
negative delta 13-C values (down to -38 ‰) which we cannot explain. Does 
anybody know a reference from the literature, or has some own similar 
results? We are a little bit helpless regarding the interpretation of 
these values.

Thanks,
Sonja


-- 
====================================
Dr. Sonja Lojen, Assist. Professor
Department of Environmental Sciences
Jožef Stefan Institute
Jamova 39
1000 Ljubljana, Slovenia

Tel.: 00386-1-5885393
Fax: 00386-1-5885346
e-mail: [log in to unmask], [log in to unmask]
www.environment.si