Photo caption:聽成人大片 post-doctoral fellow Dr Spencer Virgin is studying how limpets are adapting to warmer temperatures in New Zealand.
Dr Spencer Virgin, a post-doctoral fellow at Te Whare W膩nanga o Waitaha | 成人大片 (UC), has worked on a thesis project he has dubbed 鈥榟ot limpets鈥, exploring how these common shellfish cope with a warming climate.
Dr Virgin, from the UC School of Biological Sciences, found that as temperatures rise, limpets move towards cooler, south-facing rock surfaces to avoid overheating in the sun, with some of them moving up to five metres as the crow flies - up to 150 times their body length - to find shade.聽聽
鈥淭his behaviour means they鈥檙e quite resilient to the kind of extreme heat events that are becoming more common,鈥 Dr Virgin says. 鈥淭he most interesting thing to me, is that limpets are smarter than people give them credit for.聽
鈥淭hey know that when temperatures start to rise in spring they need to go into the shade and wait until it's cool again before they can come back out. As a result of this adaptive behaviour, I think the long-term resilience of these species is quite secure. It鈥檚 not all doom and gloom for limpets because thankfully, they're quite resilient and adaptive to heat stress.鈥澛
Dr Virgin carried out this research in Kaik艒ura, North Canterbury, and his first step was to find out the thermal tolerances of limpet species living in the area. To do this, he deployed 鈥榬obo limpets鈥 - an empty limpet shell filled with silicone gel and a tiny temperature logger. He also built portable heart rate monitors for limpets so that he could measure how heat stress affects their heart rates.
鈥淚 wanted to find out what temperature is too hot for the suite of limpet species we have in New Zealand, especially the four main ones in Kaik艒ura. The second step was looking at how they respond to that kind of heat stress in the field,鈥 he says.聽
Starting in 2022, he attached micro tags to about 850 limpets around boulders in Kaik艒ura. He visited these limpets every two weeks for one year to measure what direction the limpets were facing to see if they were moving in response to changing temperatures.
Dr Virgin says limpets are grazers so they play an important role in the healthy functioning of marine ecosystems by maintaining bare space. 鈥淭hey eat micro and macro algae, which form those slippery biofilms that grow on rocks in the intertidal zone.聽
鈥淎fter the Kaik艒ura earthquake, for example, there weren't many grazers and pretty much the whole coastline turned green because there was algae all along it. But then when the limpets and other grazers came back, they kept that algal growth down.鈥
Dr Virgin, who is Canadian, says local limpets are 鈥渟uper cool鈥. 鈥淣ew 成人大片probably has more species of limpets than almost anywhere else in the world - we've got a lot of big limpets here. I think there are 15 or 20 species of limpets in New 成人大片including one exceptionally large egg-laying, air breathing, limpet that鈥檚 common on the West Coast.
鈥淚t鈥檚 amazing how resilient to heat stress limpets are. Some of them don't really show any effects of heat stress until 38 or 39掳C, so their thermal tolerances are exceptionally high.鈥
He says they have another quirky feature in that they are able to slowly 鈥渂ulldoze鈥 other shellfish and barnacles out of their path using their shell.聽聽
鈥淚f something settles too close to a limpet, like a barnacle or something, they鈥檒l put the edge of their shell down and kind of bulldoze that animal out of their way. To deal with this behaviour, small limpets of some species will live on top of the bigger ones so they don鈥檛 get bulldozed.鈥
Dr Virgin is furthering his research under a Ministry of Business Innovation and Employment-funded programme assessing stressors to the marine ecosystem, led by UC Distinguished Professor David Schiel and University of Waikato Professor Chris Battershill. Dr Virgin is assessing differences between North Island and South Island limpets in terms of heat exposure and thermal tolerance. He is also investigating why a cold-water limpet species that was present in Kaik艒ura until the early 2000s is no longer found anywhere north of Oamaru.聽聽
SDG 14 - Life below water
