Rehousing the Molluscan Collections at the Academy of Natural Sciences of Philadelphia

Academy Of Natural Sciences Philadelphia, Philadelphia PA

Investigators

Abstract

A grant has been awarded to the Academy of Natural Sciences of Philadelphia under the direction of Dr. G. Rosenberg to rehouse the mollusk collection, which are the oldest and second largest in the United States. Mollusks comprise the most diverse animal phylum after the arthropods, with more than 100,000 species, and are abundant in terrestrial, freshwater and marine habitats. Specimens in the collection document the diversity and distribution of mollusk species throughout the world and provide direct records of environmental change via chemicals incorporated in their shells. The collection consists of about 450,000 catalogued lots containing about 8 million specimens, with greatest strength in shallow-water marine mollusks from the tropical Indo-Pacific and Western Atlantic and worldwide freshwater and land mollusks, including many species now threatened, endangered or extinct. The collection contains 12,000 lots of type specimens from more than 400 researchers. Types are the specimens used in the naming of species; they serve as standards of comparison for confirming species identities. Specimens in the collection are threatened by acid vapors given off by the wooden interiors of the current storage cabinets. Wood and other forms of cellulose such as cotton, cardboard, and paper give off acetic and formic acid. These acids react with the surfaces of the shells, especially in conditions of high humidity, converting the calcium carbonate matrix to white crystals of calcium acetate and calcium formate. This destructive process is called Byne's disease. Byne's disease obscures and obliterates features of the shells and if left unchecked can completely destroy specimens. Calcium acetate and calcium formate are hygroscopic, meaning that they absorb moisture from air, which accelerates the process of the disease. Another threat is glass disease, a condition that affects the vials in which most of the smaller specimens are stored. Sodium and potassium oxides in older vials made of soda and potash glass are also hygroscopic. As the glass absorbs water and carbon dioxide from air, sodium and potassium carbonates form, both of which are extremely hygroscopic. The continuing reaction weakens and clouds the glass. The carbonate solution can cause deterioration of the periostracum, binding proteins within the shell matrix, and any body remains dried within the shells. Such dried remains are potentially useful for DNA analysis and need to be preserved. To safeguard against Byne's and glass disease, the collection will be rehoused in modern archival materials. The 243 wooden-interior cabinets will be replaced with steel cabinets containing aluminum drawers, 320,000 old glass vials with borosilicate vials, cotton and cork stoppers with polyethylene stoppers, and 390,000 cardboard trays with acid-free equivalents. The impact of this work will be to preserve the collection for future research and education. The collection is used by scientists throughout the world. In the past 10 years, 445 loans totaling 47,000 specimens have been made, and more than 440 scientific articles have acknowledged use of collection resources. In that same period, several graduate students and post-doctoral students have received part of their training working with ANSP's curators of mollusks, and more than 1500 people have visited the collection, including 358 professional researchers, 88 graduate students doing thesis research, and more than 1000 members of the general public who participated in behind-the-scenes tours. Specimens are also exhibited on the floor of the museum and are loaned to local schools for teaching.