Analysing historical bone specimens of Antarctic whales and seals
SEACHANGE researchers from the Universities of Exeter and York have been processing whale and seal bone material as part of the work package 5 focusing on Antarctica. They are trying to answer the question of whether extensive whaling had significant impacts on the marine ecosystem of the region. In this study, we want to describe the ‘baseline’ isotopic signatures of key Antarctic marine mammal species in the 19th century when marine communities around the Antrarctic Peninsula were effectively pristine and how they changed over the 20th century. Based on these results we seek to find out how the ecosystem has responded to the recent reduction in the intensity of whaling.
Richard Sabin, Principal Curator of the collection of mammals, Natural History Museum
This work began in early 2023 by contacting the Natural History Museum (NHM) in order to identify availability of specimens from waters surrounding Antarctic Peninsula. By analysing the NHM databases, kindly provided by Richard Sabin (Principal Curator of NHM mammal collection, see above) we had to select a dataset from more than 500 specimens collected around Antarctica during the last two centuries. These were historic expeditions - HMS Alert cruise to Straits of Magellan (1876 to 1884), RRS Discovery and RRS Discovery II cruises and shore-based investigations of whale biology in the Southern Ocean (1920s to 1950s), and other research expeditions of the heroic age at the turn of the 20th century.
Evgeny Genelt-Yanovskiy collecting a sample from vertebra of blue whale.
After considering which samples were most appropriate to this study, we arranged two visits to NHM collections in order to get actual bone samples. This was quite an interesting task in itself. As expected, whale bone specimens can be presented by either a complete skeleton, or particular bones, especially ear bones (which are real treasures as the age of whale can be potentially identified from them), or even pelvic bones, that are very small in whales compared to the complete skeleton. Small pelvic bones of giant baleen whales are conventionally considered as vestigial structures, which they may not be.
Anna Genelt-Yanovskaya collecting a sample from pelvic bone of blue whale.
Anna and Evgeny had a great time with Richard examining the fantastic NHM bone collection. Since seal and whale specimens collected during that period had not only biological but huge historical significance, each drilling or cutting point at the bone selected was accurately discussed to allow better preservation of the bone and which might allow subsequent analysis for our research goals to be undertaken.
Our sampling setup at NHM bone collection
To make the sampling as least destructive and as effective as possible, we had long discussions before the sampling trips with James Scourse who is leading Work Package 5 and initiating this study, as well as with Oliver Craig and Kweku Afrifa from the University of York. It is a general practice to use conventional (and maybe not very ’scientific’) tools to collect samples from marine mammals (e.g. pliers, side cutters, hole punchers and Dremels). These torture instruments are often mentioned as ‘handheld tools’ in the Materials and Methods sections of research articles on seals and whales. So, while our sampling setup looked more like a DIY workbench in a garage, we tried to make it as precise as possible.
Bone collection of leopard seals (Hydrurga leptonyx) at Natural History Museum
After collection was complete, these samples were delivered to BioArch (University of York) and responsibilities were transferred to Kweku and Oliver. On commencing the analysis they were soon faced with some problems which needed overcoming. The unique NHM climate conditions in which the bones had been stored had a significant effect on the state of the bones. Thus the subsequent processing was as difficult as if the bones had been collected from archaeological sites. The bones spent nearly a month in acid, eventually yielding enough collagen for stable isotope analysis. After a few further problems with equipment not functioning as it should analysis was able to continue with plenty of data being generated for interpretation in the new year.
Skull of South American fur seal (Arctocephalus austalis) collected in Patagonia before 1879 (NHM, London)
