How Limpets Mitigate Climate Change and Help Coastal Ecosystems

The humble limpet is a common shellfish found across intertidal rocky shores, the area along the shore between the high tide and low tide sea levels.

These aquatic snails, characterised by their conical-shaped shells, are usually seen firmly latched to rock surfaces and are easy to ignore. However, they are savvy in adapting to high temperatures due to climate change.

A study by Dr Spencer Virgin, a postdoctoral fellow at the School of Biological Sciences, University of Canterbury, New Zealand, explores how these typical shellfish cope with warm temperatures.

Dr Virgin is amazed at limpets’ ability to cope and adapt to rising temperatures by moving to cooler surfaces and shaded areas to avoid the sun’s scorching heat by moving up to five metres, equivalent to 150 times their body length.

He also adds that limpets know when to move, and this trait highlights how resilient they are: “They 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’s not all doom and gloom for limpets because thankfully, they’re quite resilient and adaptive to heat stress.” 

Dr. Virgin conducted a year’s worth of observations, monitoring the movements and behaviours of limpets twice a week. He utilised “robo limpets,” which are empty limpet shells equipped with tiny temperature loggers, and he also developed a portable heart monitor to track how heat affects their heart rates.

Since 2022, he has attached these micro heart monitors to 850 limpets living among the boulders of Kaikōura. His research has shown that these limpets are resilient to heat stress, tolerating temperatures up to 38°C or 39°C.

Limpets’ ecosystem service

These humble shells provide an essential environmental service. When the tide comes in, they move around rocks and feed on algae with their tough tongues. Algae can be both beneficial and harmful. Phytoplankton, a type of single-celled algae, are a vital food source for aquatic life and account for half of Earth’s photosynthetic activity.

However, some varieties, like certain cyanobacteria, produce toxins that can harm humans, fish, and other animals. Under specific conditions, these algae can reproduce rapidly, causing algal blooms that cover large areas. For instance, in August 2014, a cyanobacterial outbreak in Lake Erie led to a drinking water ban for over 400,000 residents in Toledo, Ohio (The good, the bad, 2015).

A study published in Science Advances examined mini-ecosystems on the rocky shores of British Columbia. It found that sea creatures like starfish, anemones, mussels, barnacles, and seaweed are threatened by extreme temperatures during heat waves, which have caused mass mortality among intertidal species.

These ecosystems rely on a delicate balance, and the removal of key organisms can lead to their collapse. The study finds that limpets, a primary herbivore, are crucial for maintaining this balance; they consume algae, preventing overgrowth and ensuring sufficient space for other plants and animals to move in, leading to more diversity and variety in these ecosystems on the rocky shores.

The researchers discovered that during summer, when temperatures peaked, communities could thrive even if they experienced heat, but only when limpets were present.

Dr Rebecca Kordas, the study’s lead author, added, “When limpets were part of the community, the effects of warming were less harsh.” Consumers like limpets, sea otters, and starfish are very important to maintaining biodiversity, especially in aquatic ecosystems. Losing these species can destabilise ecosystems, but protecting them can make ecosystems more resilient (Dunning, 2017).