Mr Spencer Virgin1, Dist. Prof. David Schiel1
1University Of Canterbury, Christchurch, New Zealand
Limpets are conspicuous and abundant inhabitants of most temperate rocky shores. However, little is known in New Zealand about their behavioural and physiological responses to thermal stress and food availability, which have become important since the 7.8Mw Kaikōura earthquake uplifted 130km of coastline, killing most limpets. To test how limpets responded behaviourally to thermal stress, we recorded the locations of tagged limpets on 18 boulders every 2-4 weeks over a year. Chlorophyll a (food availability) was measured monthly for each compass direction (north, south, east, west) using concrete tiles. Temperature was measured every 10 minutes using biomimics (robolimpets) and HOBO pendant dataloggers. To test if limpets responded physiologically to thermal stress, we recorded i) in situ body temperatures and heart rates of limpets facing different directions on warm, sunny, days and ii) HSP70 concentrations of limpets facing different directions at 3 sites in winter and summer. As thermal stress increased seasonally, limpets moved from hotter to cooler directions. Unsurprisingly, maximum heart rates were higher in limpets facing hot directions, but this did not translate into differences in HSP70 concentrations. Interestingly, HSP70 concentrations were higher in early summer than late summer or winter, potentially reflecting the abrupt increase in temperature from fall to summer. Food availability was generally higher in winter than summer, and lower in hotter than cooler directions. Coupled with performance models from previous work, these results allow us to determine how abrupt mortality events and increasing thermal stress affects limpet populations, with potentially cascading effects on intertidal communities.
Presentation Slides – Spencer Virgin
Biography:
Spencer is a maple syrup guzzling, poutine munching, plaid wearing Canadian and is in the final year of his PhD at the University of Canterbury. His PhD research focuses on understanding ecophysiology of limpets on New Zealand rocky shores.
