Re: vital effects and genetics

From
Date
Eric, 

You’ve received some good replies from Peter Roopnarine, Stefan Bengtson and
Stephen Schellenberg discussing non-genetic vital effects and the possible
role of symbionts. The references below dealt with vital effects on deep-sea
forams that showed fractionation differences when other physical
environmental parameter variances are minimal. 

Basically, I do not think we completely understand the fractionation
phenomena that we observe. The microhabitat influence hypothesis has been
invoked - however, geochemist might argue that diffusion is too high to
argue for interstitial variances to be significant. The food source
variances might be important - especially for carbon variances, but a
difficult argument for oxygen isotopic variances. Further, we noted that
isotopic variances between species was not always consistent – a rather
bothersome/disconcerting fact when we try to tie data in a time-series
sequence with discontinuously ranging benthic taxa.

Morphological isotopic variances, as far as I know, have not been looked at
too seriously – worthy of investigation. There tends to be morphologic
correlations however - but not clearly so. E.g. the flatter
Cibicides/Planulina, etc. seem to be the ones nearest isotopic equilibrium
and tend to be surface dwellers or attached forms vs. fusiform/elongated
type indicative of burrowers/infaunal types. Sometimes we have no choice on
what taxa to run - hoping that the variability in the signal is greater than
the interspecific variances.

Corliss and others have done a fair amount of infaunal work to better
understand distribution/habitat, etc. Morphologic work has also been done.
No offense intended for the good work of others I might overlook here. A lot
of assemblage work on benthic foraminifera has shown closer linkages to
surface productivity changes than has been appreciated prior to those studies. 


Belanger, P.E.; Curry, W.B.; Matthews, R.K., 1981.  Core-Top Evaluation of
Benthic Foraminiferal Isotopic Ratios for Paleo-Oceanographic
Interpretations.  Palaeogeography, Palaeoclimatology, Palaeoecology 33; 205-220.

Chen, JiaJie, 1994. Benthic foraminiferal isotopic compostion: implications
for late Neogene-Quaternary Paleoceanography of the Indian Ocean – Brown U.
Dissertation --- I don’t know where it may have subsequently been published.

Graham, D.W.; Corliss, B.H.; Bender, M.L.; Keigwin, L.D., 1981.  Carbon and
Oxygen Isotopic Disequilibria of Recent Deep Sea Benthic Foraminifera.
Marine Micropaleontology 6; 483-497.

Vincent, E., Killingley, J.S., and Berger, W.H., 1981.  Stable isotopes in
benthic foraminifera from Ontong-Java Plateau, box cores ERDC 112 and 123.
Palaeogeography, Palaeoclimatology and Palaeoecology, 33, pp. 221-230.

Woodruff, F.; Savin, S.M.; Douglas, R.G., 1980.  Biological fractionation of
oxygen and carbon isotopes by Recent benthic foraminifera.  Mar.
Micropaleontology 5a, pp. 3-11.



**********through summer sometime 1996**************
NEW email: belanger@darkwing.uoregon.edu
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Paul E. Belanger                 
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