Quirks & Quarks

A research assistant named Spongebob? Sea sponges collect data for science

Sponges turn out to be natural filters for capturing environmental DNA samples from the ocean

Sponges turn out to be natural filters for capturing environmental DNA samples from the ocean

Some of the sponges that were tested in the study (A. Riesgo-Gil)
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Researchers in the UK have been able to recruit sea sponges to help them gather data about hard-to-observe creatures in the ocean. The sponges may be able to capture environmental DNA, or eDNA from the ocean much more efficiently than conventional research methods.

"They do the job that they have evolved to do for millions and millions of years, and we are only trying clumsily to mimic by going into the water and collecting and filtering this water," said Stefano Mariani told Bob McDonald in an interview with Quirks & Quarks. Mariani, who's Chair in conservation genetics at the University of Salford in Manchester, led the work.

Some of the sponges that were tested in the study (A. Riesgo-Gil)

In the last few years eDNA has become a valuable tool for understanding which organisms are present in ecosystems. Plants, animals and microbes are constantly shedding DNA to the environment in waste products like urine or feces, or bits of tissue like shed skin. Scientists extract this eDNA from soil, sediment, or water samples, and tease out a surprising amount of information from it.  

However the process is cumbersome and requires laborious sampling and filtering.  Mariani and his colleagues realized that this is something that sponges do naturally. Sponges filter thousands of litres of water through the small pores in their body every day, extracting nutrients along the way. Pieces of debris containing eDNA also enter the sponge and some of it ends up sticking to sponge's tissues.  

eDNA left by Weddel seal was found in the sponge samples tested in the study (S. Taboada)

Mariani and his team tested how effective the sponges were by cutting small pieces off sponges and analyzing them for DNA.

Altogether, they identified 31 species in the small number of sponge samples they collected from the Antarctic and Mediterranean. Many of the DNA samples were from fish, but, they also found DNA from Weddell seals and chinstrap penguins.

The team still needs to do more tests to validate the effectiveness of this approach, by comparing it to conventional eDNA collection methods. Mariani holds out great hope for the technique which he thinks could be used widely, since sponges are ubiquitous in the marine environment.  And ultimately the labour saving potential of sponge sampling could make it a promising tool for capture eDNA. 

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