Posts Tagged ‘Collembola’
Way back when, during the early days of this blog, I wrote a piece about some fairly degraded bulk samples hiding in plain view on our shelves (oh, the heartbreak!). Well, while searching for information about our next NC insect of the week I came across a series of equally heart-wrenching bulk samples containing springtails. Behold:
Hmmm…doesn’t look so bad…or does it? We have 40 of these large glass jars, each containing about 30 shell vials. The shell vials themselves hold undetermined collembolans from multiple collecting events in the 1950s and are capped with natural corks (AHHH!). Over time these corks leached tannins into the alcohol (hence the rich, tawny hue of that “tea”), making the medium acidic and bad for preservation. No sweat. Simply replace the tea with fresh alcohol and the corks with polyester fill. Right? (Might replace the glass as well, with proper shell vials.) But what about this unfortunate situation:
Double AHHH! The jar is completely dried out, save for some mystery goo at the bottom, and most of the corks have long since become disassociated from their vials:
Collembolans collected on moss on Mt. Timpanogos, UT, July 19, 1951 by G. F. Knowlton and T. Tibbetts.
Unfortunately we can’t go back in time and recollect these specimens, so a salvage mission is warranted. Are there any specimens left in that goo at the bottom? If so, what kind of shape are they in? Can we trust that they are in their appropriate vials, given that the corks popped off long ago? “Why not simply deaccession these lots and dump them in the trash?” asked a friend. Well, it’s our moral obligation to the collector and to collembologists that we at least attempt a rescue.
I rinsed the above vial with 80% ethanol, dumped the stew into a watch glass, and proceeded to pore over its contents. Dirt, chunks of cork, brown sludge…ah ha! There are specimens in there, and they appear to be in decent shape (to a non-collembologist, anyway):
(Thanks to Amy Bader for this image!)
Ok, so what’s the next step? Replacing the hardware and preservative is a no-brainer, but what about environmental conditions? Will increasing the pH back to neutral and the ethanol from some low, unmeasurable percentage to 80% damage the specimens? We also need to document this process and label the vials accordingly. Here’s what we’re reading (below), but we’d appreciate any feedback we get from someone in the know. Hopefully I’ll remember to post a follow-up!
Marhue, L. 1983. Techniques to restore dried-up invertebrate specimens. In: Proceedings of the 1981 Workshop on the Care and Maintenance of Natural History Collections. D. J. Faber, ed. Syllogeus No. 44: 175-177. [our specimens are not totally dried out, so I think we're safe]
Cushing, P. E. and J. A. Slowik. 2007. Re-curation of alcohol-preserved specimens: comparison of gradual versus direct specimen transfer on specimen condition and assessment of specimen value. Collection Forum 22 (1-2): 1-9. [this study revealed no detrimental effects when ethanol concentrations were increased]
Van Cleave, H. J. and Ross, J. A. 1947. A method for reclaiming dried zoological specimens. Science 105 (2725): 318. [our specimens are not totally dried out, so I think we're safe]
Vogt, K.D. 1991. Reconstituting dehydrated museum specimens. Curator 34 (2): 125-131. [our specimens are not completely dried out, so can we avoid treatments with trisodium phosphate, surfactants, acetic acid, boiling, graded ethanol series, etc.?]