Marine life and climate change: An evolutionary advantage

The Crown of Thorns Starfish

We have all heard the term ‘climate change’

But we don’t often hear about how climate change affects an individual species. The crown of thorns starfish is one example of how climate change can benefit a species.

The crown of thorns starfish (Acanthaster Planci) is a massive multi-limbed starfish that can even survive even being cut in half (Engelhardt and Lassig  1993, p71-79). So how could such a resilient creature benefit from climate change?

Acanthaster Planci: Crown of thorns starfish

Starfish life

The Crown-of-thorns starfish (COTS) eat coral polyps and live in the Indo Pacific region of the ocean. Under normal conditions, the COTS population is regulated by predators such as the Triton sea snail. However, in the past 30 years COTS population has increased by up to 6 fold in waves causing mass loss of reefs (Birkeland and Lewis 1990)

Above: The Triton Sea Snail attacking a starfish

The cause

Crown of Thorns Starfish outbreak

Scientists have found that the two most likely causes of outbreak are nutrient run-off and climate change. Evidence has shown that excess nutrients in the ocean increase the number of phytoplankton that larval COTS feed off (Brodie et al, 2005). Another study (Uthicke et al. 2015) found that increased sea temperature of 2 degrees increases larval growth rate by 240%. This along with a reproduction rate of approximately 50 million eggs per female per spawn is causing outstanding issues for coral reefs (Birkeland and lewis, 1990).

Coral damage caused by Starfish

The change

With an increased larvae survival rate, COTS are more likely to disperse to new areas, face new challenges and evolve (Benzie 1999). It also allows starfish that would normally die in the larval stage to reproduce and change the gene distribution within the population rapidly (Nishida and Lucas 1988). This can and has led to some genetic drift within populations (Benzie and Wakeford 1997). This is just example of how climate change can benefit a species.

For more information on the COTS click here

Check back next week for more information on how climate change is affecting marine life. Thanks for reading. J

References:

Benzie J, Wakefore M, 1997, ‘Genetic structure of crown-of-thorns starfish (Acanthaster planci ) on the Great Barrier Reef, Australia: comparison of two sets of outbreak populations occurring ten years apart’, Marine Biology, vol 129, no.1, pp. 149-157, viewed 15/3/15, url: http://link.springer.com/article/10.1007/s002270050155#page-1

Birkeland C, Lucas J, 1990, Acanthaster Planci: Major Management Problem of Coral Reefs, CRC Press, United States.

Brodie J, Fabricus K, De’ath G, Okajc K, 2005, ‘Are increased nutrient inputs responsible for more outbreaks of crown-of-thorns starfish? An appraisal of the evidence’, Catchment to reef: water quality issues in the Great Barrier Reef region, vol.51, no.1-4, pp.266-278, viewed 15/3/15, doi: 10.1016/j.marpolbul.2004.10.035

Engelhardt U, Lassig B (ed) 1993, The possible causes and consequences of Outbreaks of the Crown-of-thorns Starfish, Great Barrier Reef Marine Park Authority, Australia.

J.A.H. Benzie, 1999, ‘Genetic differences between Crown of thorns starfish (Acanthaster Planci) populations in the Indian and pacific oceans’, Evolution, vol.53, no. 6, pp.1782-1795, viewed 15/3/15, url: http://www.jstor.org/discover/10.2307/2640440?sid=21106116781373&uid=4&uid=2

Nishida M, Lucas J, 1988, ‘Genetic differences between geographic populations of the Crown-of-thorns starfish throughout the Pacific region’, Marine Biology, vol.98, no.3, pp. 359-368, viewed 15/3/15, url: http://link.springer.com/article/10.1007/BF00391112#page-1

Uthicke S, Logan M, Liddy M, Francis D, Hardy N, Lamare M, 2015, ‘Climate change as an unexpected co-factor promoting coral eating seastar (Acanthaster planci) outbreaks’, Nature, no. 8402, viewed 15/3/15, doi: 10.1038/srep08402