Aquatic viruses can alter the climate. I study
Microbiologists have discovered a very important player in air pollution. This is what, as a whole, we can call the marine virome
While we usually focus on deforestation as one of the worst actions capable of degrading the climate, decreasing the amount of carbon dioxide that can be sequestered from the air and transformed into organic matter, and knowing that the microscopic algae of the sea contribute abundantly to the same process, microbiologists have discovered a further, very important player in the game hitherto overlooked. This is what, as a whole, we can call the marine virome, an army of Darwinian replicators estimated to consist of 1030 individual virus particles, about 1000 times the number estimated for stars in the cosmos. As is natural, all aquatic organisms are affected by their presence in one way or another, be they bacteria, algae, protists or fish; but while we are well used to considering the interactions of parasitosis, symbiosis and commensalism that can affect each type of virus and many other living species, only recently have we begun to appreciate a global role for the marine virome, which acts on the entire biosphere.
Among marine viruses, bacteriophages (or simply phages), viruses that infect and kill bacteria, are the dominant ecological type in the ocean. Phages are estimated to kill 10 to 20% of heterotrophic bacteria and 5 to 10% of photosynthetic bacteria in the ocean each day, resulting in a significant release of carbon, nutrients and other trace elements into the microbial food web. Now, in the absence of the action of the phages, the bacteria they prey on would mostly be preyed on by other organisms, i.e. as secondary consumers, thus moving up the food chain; at each cycle of predation by increasingly apical organisms in the trophic chain, a good part of the organic matter consumed is used to produce the energy necessary to sustain the life of the predatory organisms, consuming oxygen and releasing carbon dioxide into the environment. Instead, phages detonate their bacterial hosts through a process known as viral lysis. As bacteria die and undergo decomposition, their organic matter has the potential to contribute to the particulate organic matter (POM) pool and dissolved organic matter. POM consists of complex structures and is not easily broken down by marine microbes. As a result, it is often transported to the deepest parts of the ocean, siphoning carbon from the environment on a more or less permanent basis.
The dissolved organic matter, on the other hand, feeds a new generation of microbes, including a wide variety of bacteria. Now, we must consider that only some types of bacteria have aerobic respiration, ed they emit CO2 when they assimilate the food they eat; many, on the other hand, use different types of processes to obtain energy and "digest" food, and do not produce that type of greenhouse gas. Thus, viral lysis promotes bacterial respiration which traps carbon in the oceans instead of releasing it into the atmosphere, preventing a large proportion of organic matter from moving up the food chain. In this way, phages have been estimated to help indirectly sequester about 3 gigatons of carbon per year. Therefore, viruses, whose weight is already enormous both in natural selection and in the generation of new genetic variety, they can also alter the chemistry of our atmosphere and, therefore, the climate. The pathways of ecosystems are complex, and sometimes the smallest of components can play a huge role in determining effects on a macroscopic scale.
