19. Acclimation to environmental change: a long term record of a New Zealand brachiopod

Cross, E. L. (1,2)*, Peck, L. S. (1), Harper, E. M. (2)

1 British Antarctic Survey, Cambridge, CB3 0ET, UK
2 Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, UK

Background
Since the Industrial Revolution, rising atmospheric CO2 levels have altered our oceans through warming and acidification. Current insights about species responses to environmental change are largely based on laboratory experiments and comparative field analyses, which provide useful insights into how natural populations may respond. However, these approaches do not tell us about how populations have changed in response to changing environments. Historical data from museum collections of shells provides an approach to test predictions from experimental and comparative analyses and, in conjunction with these methods, can be used to better predict the vulnerabilities of marine calcifiers to environmental change.

Methods
Shell characteristics were analysed from museum collections of the common New Zealand brachiopod Calloria inconspicua collected from the same sampling site in Stewart Island every decade since 1900 to the present day to determine any variation over time.

Findings
Over the last century, calcification index, total shell thickness, primary and secondary layer thickness, punctae (shell perforations) density and elemental composition of the shell have not changed. However, shell density has increased by 3.05% which can partially be explained by a decrease in punctae width by 8.26%.

Conclusions
This unique and valuable dataset indicates the resilience of possibly one of the most highly calcium carbonate dependent organisms to environmental change in their natural habitat over the last 110 years. The results also provide an insight into how this species might react to future change and its possible ability to adapt.