It's fair to say that there are more than enough viruses in the world right now.
The incredible vastness of the virus sphere can hardly be overestimated. While several thousand types of viruses have been studied in detail, scientists say we haven't even scratched the surface. Some people think there could be a trillion species in total.
Even more conservative estimates are staggering. The oceans can hide tens of millions of different species, and they are not at all difficult to find: 10 million viruses can be present in a milliliter of water.
Despite all this, it is encouraging to be reminded of two constants, each of which is present in a new study by marine ecologist Jennifer Welch of the Royal Netherlands Institute for Marine Research (NIOZ).
In short: not every virus infects all living things, and some animals actually hunt viruses, in a sense, removing them from the environment. Despite this underestimated service, much of what lies at the heart of this phenomenon remains a mystery.
“Viruses are the most common biological species in the marine environment, but despite their potential environmental impacts, little is known about the absorption of viruses by non-host organisms,” explains Welch in a new article.
In a series of experiments conducted in the laboratory, the researchers examined how a range of non-host marine organisms cope with the removal of viral particles from their aquatic environment – either through active predation or through passive mechanisms such as filters and organisms that create physical barriers between viral parasites and their hosts.
Of the 10 different animal species tested, crabs, shells, oysters and sponges were found to be the most effective in reducing the virus.
“In our experiments, sponges reduced the presence of viruses by up to 94 percent within three hours,” explains Welch, although after 24 hours this figure even reached 98 percent virus removal.
“Another experiment showed that the absorption of viruses is indeed very fast and efficient. Even if we offered new viruses to the water every 20 minutes, the sponges remained extremely effective at removing viruses. '
Compared to the sponges tested, crabs were in second place in terms of effectiveness: they reduced the number of viruses by 90 percent in 24 hours, while shells coped with 43 percent, and oysters – 12 percent.
Of course, these impressive laboratory results may not be as successful in the wild, given the range of behavioral changes that can occur in a biodiverse aquatic environment, not to mention the myriad other environmental variables playing underwater.
“The situation is much more complicated there, as there are many other species of animals and they all influence each other,” says Welch.
'For example, if an oyster filters water and a crab appears, it closes the valve and stops filtering. In addition, factors such as tidal currents, temperature and ultraviolet radiation must be considered. '
However, the researchers believe that this natural ability of animals to reduce viral particles in the marine environment is something we might one day use. Especially in aquaculture, where organisms such as sponges can be used as a kind of shield to help protect the farm population from viral pathogens.
Whether this will eventually be possible remains to be seen, but it is clear that this ongoing process of removing viruses from the oceans is still underestimated.
“The impact of organisms on the environment is indeed a factor that is overlooked in viral ecology,” says Welch.
The results are presented in Scientific Reports.
Sources: Photo: NOAA
