Starfish have to warm to new task
It’s a remarkably simple climate change experiment and the predicted results may surprise. Will Harvie reports.
How many readers know much about starfish? Colourful, interesting shape, beloved by children, slow movers. Actually they’re cooler than that.
The most common species near Antarctica New Zealand’s Scott Base are omnivorous scavengers that feed primarily on seal carcasses and faeces. About 10cm across when adult, Odontaster validus can live up to 100 years and can survive as deep as 600m.
They’re also a useful species for climate change researchers.
That’s because Antarctic starfish will have to adapt to changing conditions and it’s possible to model those conditions in a lab, something impossible using larger and more mobile species.
Early this spring, University of Otago associate professor Miles Lamare and colleagues captured 600 starfish from the Ross Sea. They will rear them in refrigerated tanks over the next two years in Dunedin to monitor their adaptability to climate change.
The starfish will be raised both ‘‘under present day conditions and under conditions predicted for the Antarctic at the end of the century,’’ Lamare explained in an Antarctica New Zealand programme summary.
Those scenarios predict seawater will be 2-3 degrees Celsius warmer and more acidic than today. The food made available to the starfish will also be a variable.
Starfish will be ‘‘sacrificed’’ at set intervals over 18 months to determine if and how they are adapting to different conditions. Many will procreate and these offspring will be sacrificed as well.
Lamare and colleagues will be testing these starfish’s ‘‘capacity to adapt’’, he said in the summary.
One mode of adaptability is called ‘‘transgenerational plasticity’’. In simplified terms, it’s whether children can tolerate changed conditions better than their parents. More precisely, it’s whether ‘‘the offspring of parents subjected to changes (ie warmer conditions) are more tolerant of the new environment’’, Lamare said.
This is possible if a mother invests more resources into eggs to make them more resilient to environmental change.
Lamare and colleagues from Auckland, Sydney, Delaware and Brussels hypothesise that the research may conclude ‘‘polar species respond to climate change by producing more robust offspring’’.
That’s right. This species of starfish may do better as a result of climate change.
Or, more precisely, some individuals will respond robustly and evolution will select them. In an interview, Lamare said over time the population could adapt to warmer and more acidic waters.
Transgenerational plasticity is also possible through a process called ‘‘epigenetics’’. In simplified terms, it is genes expressing differently rather than a change in the genetic code itself.
It’s the same genes doing slightly different things rather than changing.
Lamare’s team hope to show ‘‘all is not lost’’ in terms of climate change and that ‘‘biology has many tools available to persist in the face of climate change’’.
This hopeful note doesn’t detract from the seriousness of climate change, but rather adds to the growing body of research showing climate change is complex and will produce winners and losers.
Nor does it predict the survival of this species of starfish. Other factors could yet contribute to their decline, including wider ecological changes, loss of sea ice and reduced food supply.
Meanwhile, Lamare is involved in a similar experiment with starfish from Australia’s Great Barrier Reef. Food is more abundant there compared with Antarctica but it’s possible starfish species from the reefs won’t adapt as quickly to warming and acidifying seas.
Lamare got his PHD in marine science from Otago in 1997 and has visited Antarctica at least 16 times. His early work looked at the effects of ultraviolet radiation on Mcmurdo Sound marine species.
These days he’s also interested in the response of marine invertebrates to increases in sea temperature and whether warming of New Zealand oceans could see the expansion of warmwater species into northern New Zealand.
The Antarctic starfish he’s studying are ‘‘abundant, they travel well, they’re happy in the lab and we’ve got lots of experience with them’’.
Unfortunately, ‘‘it’s a one-way ticket’’.