Scientists have discovered that sponges which can filter 10,000 liters of water daily are also able to catch DNA of water-dwelling animals in their tissues. The study draws attention to the fact that sponges can be used to examine biodiversity, when seal, fish and penguin DNA from the Antarctic and Mediterranean were found in sponges.
The study drew attention to the fact that just like humans left DNA in places they inhabited, water-dwelling animals also left DNA in water bodies. It was also realized through the study that sponge DNA did not interfere with the ability to identify DNA of other species which was caught within the tissue. Moreover, by using a specialized DNA primer- a short sequence of nucleic acid, scientists could selectively amplify vertebrate DNA.
“Sponges are ideal sampling units because you find them everywhere and in every aquatic habitat, including freshwater. Also, they’re not very selective filter-feeders, they don’t run away, and they don’t get hurt by sampling – you can just grab a piece, and they will regenerate nicely,” says Stefano Mariani, marine ecologists and population geneticist at the University of Salford.
Scientists are using sponge DNA along with metabarcoding which helps to sort DNA from the tissue sample, allowing it to be distinguishable and more species-specific. The species identified through the experiment were fish, but another sample from Antarctica also included DNA from chinstrap penguins and Weddell seals. The sample was identified to be from an offshore penguin breeding colony. “This was a really exciting find and also makes a lot of sense, because the penguins would be in and out of the water a lot, eating, swimming, and pooing,” says Mariani.
This process of natural sampler could be effective than the current process which uses machines with large water-sampling capabilities. Moreover, with the sponge tissue, there are lesser risks of DNA contamination, as the tissue has filtered out most of the water. Since DNA found in water is extremely diluted, the water needs to undergo extreme filtering which makes it more open to the danger of DNA contamination. Moreover, sponge tissue is more portable, since machines can be disruptive and fragile to ecosystems.
Through this experiment, scientists are aiming towards improving the collection of environmental DNA in order to improve the study of biodiversity by using sustainable methods. If DNA sponges are effective enough in capturing biodiversity, only further research will tell, but at least the foundation for it has been laid. “I am hopeful that this method will prove itself to be useful,” Mariani says. “It’s the quintessential environmentally friendly biodiversity assessment tool.”