Contemporary Surveys and New Explorations
Guest post by Nathan V. Whelan
Natural history collections are an invaluable resource for understanding historical biodiversity, but historical collections are especially valuable when coupled with specimens from modern surveys. Whether such surveys are a part of long-term ecological studies, systematic revisions, or biodiversity assessments carried out by state or federal wildlife agencies, they provide information about shifts in diversity and community assemblages. This is incredibly important in an age of anthropogenic degradation of natural ecosystems and rapid climate change, because it allows us to understand how such processes are influencing biodiversity. Equally as important are recently deposited specimens from places never before explored. It may be easy, in our interconnected world, to passively assume virtually everywhere on earth has been explored, but many ecosystems, particularly the deep sea, have hardly been touched by scientists. Many research labs participating in biodiversity studies are well suited for short-term storage of specimens, but museums are uniquely poised to preserve and store specimens for other scientists and future generations.
I have been fortunate enough to participate in both biodiversity surveys of places that have a long record of research activity (e.g. the Tennessee River) and in new places where few, if any, biological samples have been collected (e.g. the deep sea floor of the northeast Pacific Ocean). How and where these different types of collections are deposited can vary considerably. For example, when I deposited freshwater snails of the family Pleuroceridae from the Mobile River Basin in Alabama for my dissertation, I sent vouchers to the Smithsonian National Museum of Natural History. Their invertebrate zoology collection is well established and accessible to a diverse array of scientists, and, most importantly, has many freshwater snails in the collection from the 19th and 20th centuries. This allowed for the snails I collected to be placed in a better historical context than if vouchers had been sent to a museum that had few or no pleurocerid lots.
Another important consideration is the preservation method required for the animals of interest. Freshwater snails are relatively simple, as many shells are deposited dry, but other animals are best stored in ethanol or formalin, which can add another layer of complexity into how specimens are stored. In contrast to snails, the vast majority of deep sea organisms cannot be preserved dry. I am currently participating in a research cruise on the R/V Oceanus in the northeast Pacific. The cruise includes an international team of scientists that is sampling organisms from the deep sea. We are employing a method that allows us to sample animals that have rarely been collected, and never in a systematic manner from the north Pacific. This method involves deploying “landers” containing wood and whale bone to the ocean floor at depths ranging from over 1000 meters to 2700 meters. These were placed 14 months prior to the cruise, and are now being retrieved. Among other goals, we aim to collect Xylophaga (a bivalve that bores into wood) and Osedax (a marine Annelid in the family Siboglinidae that is only found living on whale bones). These animals are incredibly rare, so samples must be processed with care and placed in appropriate preservatives. We place specimens in ethanol, formalin, and “RNA later”—a special preservative that is ideal for fixing RNA for next-generation sequencing. Other samples, such as soil from the ocean floor, are frozen in a -80°C freezer. Each of these preservation methods has a different purpose. For example, formalin is used to preserve individuals for morphological analysis, which is particularly important in the case of undescribed species.
Eventually, many of the specimens collected on my current research cruise will be deposited in natural history collections. Some will go to collections at institutions where scientists on the cruise reside (e.g. Auburn University). Others will be deposited in more established natural history collections. For all samples, special considerations will need to be made to ensure that wherever they are sent, the institution is well equipped to handle the various preservation types. Any newly described species will also need to be deposited at a museum that has a special storage area for holotypes—the one specimen that best captures the morphology of a newly described species. The animals collected on this cruise should be exceptional additions to any natural history collection because of their rarity. More importantly, scientists not involved with this cruise will be able to study our samples and further contribute to our understanding of earth’s biodiversity. Without natural history collections such studies would not be possible.
Nathan V. Whelan is a Postdoctoral Scholar of Biological Sciences at Auburn University in Auburn, Alabama. He can be contacted at email@example.com.
Next time on Cracking the Collections:
August 10 – Old Collections, New Managers post by guest blogger Ingrid Rochon!