Suttle, C.A. Nature Reviews., (2007).

"Marine viruses - major players in the global ecosystem".

Reviewed: 11/10/11


Viruses are the most abundant player in the oceans when it comes to quantity of genetic information. Viruses in general are a unique class of organisms to consider due to their ability to infect hosts at multiple trophic levels. They have the potential to exert controlling forces on autotrophs and the heterotrophic grazers that feed on them. The author of this review presents information on different aspects of viral ecology as they relate to the specifics of a marine system, as well as the molecular techniques that have been developed to quantify their abundance.
It appears as though marine virus ecology might be fundamentally different from its terrestrial counterpart. It seems to me as if marine viruses can be thought of as existing in one gigantic pool, floating and dispersing after lytic events of their host species. Whereas as in terrestrial systems we usually think about viruses as being vectored or transmitted in some more organized fashion. Along with this idea is a lack of understanding about the way that viruses are transmitted in the ocean. A significant amount of data, involving genetic sampling in many diverse aquatic habitats around the globe, seems to show that their exists hotspots for certain virus families in differential parts of the ocean. It is possible to identify commonalities in different viral lineages as well. The VHSV virus is associated with a disease in trout farms of Europe, but has also been identified in marine fish and in some lakes in North America.
Interest in amassing more data on the specific roles of viruses in the ocean can be linked to their role in turnover and shuttling of carbon and other limiting nutrients as they infect and lyse their hosts. Particulate and dissolved organic matter arising after these events increases the amount of respiration done by decomposers in the photic zone.
The author also presents an interesting analysis of the spectrum of r and K selection in both the host species of the ocean and the viruses that infect them. While it appears that the abundance of marine prokaryotes and eukaryotes is weighted towards k strategists, who are slow growing and resistant to infection, the abundance curves and r-K spectrum is the opposite in the viral community. The most abundant viruses appear to genrally fall under the header of r-selected species, those with rapid replication and generally more virulent. This contrast of host and pathogen has important implications as it indicates that the rarer host species, those that are more r-strategists and are the most susceptible to infection, are controlled by a highly abundant, rapidly-replicating pathogen community. This does not mean that r-selected host species never undergo periods of release where they rapidly reproduce and expand in concentration, but it does imply that viruses are an important control to bring the overall marine ecosystem back to a more equilibrium state. It would be interesting to attempt to quantify both the affect that viruses have on the grazer populations ability to control other dominant eukaryotes or prokaryotes and how viral effects on these lower trophic order species affects the grazers who might feed on them.