In a Sea of Stars

Ctenodiscus crispatus burrowing – filmed in the Barents Sea
Ctenodiscus crispatus

 

 

 

 

 

 

 

 

 

Today’s guest blog post is from my good friend and office mate Christina Wood.

Christina will tell you all about herself and the work she does, take it away Christina…

I am a PhD student studying at the National Oceanography Centre in Southampton, UK. In March 2017, I participated in a cruise to the Barents Sea to assist researchers as part of the ongoing MAREANO project. This project has been running for the last 10 years and aims to map the depth and topography, sediment composition, contaminants, biotopes and different habitats present throughout Norwegian waters. This leg of the project focused on mapping a transect running south of Svalbard, in the Barents Sea and was conducted aboard the research vessel G. O. Sars. My work aboard the G. O. Sars focused on the Mud Star Ctenodiscus crispatus, which can be found throughout the muddy sediments of the Barents Sea.

These little stars are important as they burrow down into the mud, helping to oxygenate the sediment and stimulating microbial growth, which contributes to nutrient cycling and release.  They also feed on the organic matter present within the mud, hence the name Mud Star.

I am interested in how mud Stars from different areas behave in terms of their bioturbation (how they burrow and mix sediments) and how they vary in terms of their reproduction. As part of this cruise I have been running onboard experiments to see whether Mud Stars from 2 different regions (one south of the polar front and one on the polar front) vary in their bioturbation.

C. crispatusburrowing in bioturbation core. see how the lumis is being worked into the sediment.

To do this I kept the stars in little aquaria, partly filled with mud. Each set of aquaria is kept at the corresponding water temperature to where we collected the mud stars. To track their movement, I used coloured particle tracers called ‘luminophores’, which I placed over the surface of the mud in a 2-3mm layer. I then left the animals for 5 days to go about their business.

I then photographed the sediment under ultra-violet light. This makes the luminophore particles fluoresce so they can be easily identified compared to the surrounding sediment by an automatic computer program and the number of luminophore pixels per sediment depth calculated.

fSPI image of bioturbation core incubated for 1 week.

Now that I am back in the UK, I am working in the lab to investigate whether there are any differences in the reproduction of the mud stars from the two different areas. I will then analyse their population genetics to see whether any differences are due to short term individual adaptation, or long term genetic variation.

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