Preservation techniques for benthic invertebrate samples

[Amy Edwards]

>At 13:31 13/4/95 -0800, Fraser R. Sime wrote:
>>The Northern District of the Calif. Dept. of Water Resources has an
>>extensive benthic invertebrate sampling program in the north state. I am
>>heavily involved in the coordination of this program. For many years, we
>>have used formaldehyde as our main preservative for benthic samples
>>collected in the field. These are archived, sometimes for many months,
>>before being id'd and enumerated, etc..
>>
>>Recent changes in safety regulations, disposal problems and concerns for
>>the environmental health of workers has forced us to look at other
>>alternatives for preserving our benthic samples. We do use ethanol for
>>short-term work, but have found it to be less than ideal over extended
>>time.
>
>Long experience with both shallow water and deep-sea benthic programmes has
>demonstrated that to obtain easily identifiable invertebrates also useful
>for taxonomy, one must fix the samples with buffered seawater/formaldehye.
>We, however, do not leave the specimens in the fixative for long, usually
>12-24 hours is sufficient.  Then the samples should be washed with fresh
>water to remove the salts, and put into 70-80% ethanol (some folks use the
>cheaper isopropanol, but it is also more poisonous). I draw a distinction
>between fixation (cross linking  proteins to "toughen up" the specimens) and
>preservation (prevention of little buggers from eating your sample).
>Buz Wilson
>Australian Museum

I agree, fixing and preserving specimens are two different things and
different chemicals need to be used for these steps because, as Buz pointed
out, they do very different jobs.  Ethanol can not be used as a substituted
for formalin fixing, and formalin can not be used as a preservative except
in very specific cases (plankton, worms & jellyfish).  If you leave samples
in formalin too long, various calcium carbonate parts (shells, spicules,
ossicles) will dissolve.  That can make them very hard to identify and
useless as specimens.

For a course we taught in 'Biological Collections Management', I developed
a manual on invertebrate collection/preservation/identification techniques.
Here are the references I used for the fixing & preserving part (several
are old, but still very good):

Anonymous.  1979.  Preservation of animals and taxonomic references.
Marine Resources Extension Center, UGA.  Unpublished man.

Anonymous.  1972.  Techniques of preservation of marine invertebrates.
University of Utah, Bio. 557: Advanced invertebrate zoology.  Unpublished
man.

Behringer, M. P.  1973.  Techniques and Materials in Biology.  McGraw Hill
Co. 660 pp.

Bianco, S. L.  1899.  The methods employed at the Naples Zoological Station
for the preservation of marine animals.  Bull. US Nat. Mus.  39: 1-37.

Cleave, H. J. and J. A. Ross.  1947.  A method for reclaming zoological
specimens.  Science 105: 318.

Fry, P. D. and D. Gray.  1987.  An enzymatic technique for the separation
of spicules from alcohol-preserved sponge tissue.  In:  Vancelet, J. and N.
Boury-Esnault ed.  NATO ASI series Vol G13: Taxonomy of Porifera.

Gohar, H. A. F. 1937.  The preservation of contractlie marine animals in an
expanded condition.  J. Marine Biology Association.  22(1): 295-299.

Humason, G. L.  1979.  Animal Tissue Techniques, 4th ed.  W.H. Freeman Co.
661 pp.
Kannemyer, S. X.  1983.  The preservation of natural color in biological
specimens preserved in fluid.  Journal of the South African Museum
Association #8.

Lincoln, R. J. and G. Sheals.  1979.  Invertebrate animals; collection and
preservation.  Cambridge University Press.

Marhue, L.  1983.  Techniques to restore dryed-up invertebrate specimens.
Syllogeus 44: 175-177.

Runham, N. W., K. Isarankura and B. J. Smith.  1965.  Methods for
narcotizing and anaethetizing gastropods.  Malacologia 2(2): 231-238.

Russell, H. D.  1963.  Notes on methods for the narcotization, killing,
fixation, and preservation of marine organisms.  Systematics-ecology
program Marine Biological Lab, Woods Hole Mass.  Unpublished man.

Thompson, J. R., M. H. Thompson and S. Drummond.  1965.  A method for
restoring dried crustacean specimens to taxonomically usable condition.
Crustaceana 10:109.

Toyama, K. and G. Miyoshi.  1963.  Prevention from color fading of aquatic
animals under preservation.  J. Tokyo Fisheries 50(1): 43-48.

Wagstaffe, R. and J. H. Fidler.  1955.  The Preservation of Natural History
Specimens: Volume 1: Invertebrates.  Philosophical Lib. Inc.

Amy Edwards, Program Coordinator ------- aedwards at museum.ent.uga.edu

Museum of Natural History        --------        phone (706) 542-4137
University of Georgia            --------            FAX 706-542-3920
Athens, GA 30602