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An Introduction to Marine Viruses

What Is a Virus?

Virus Size & StructureRe

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viru

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1 Micron

Bacterium (Staphyllococcus aureus)

Chlamydia

Pox virus

Herpes virusInfluenza VirusPicornavirus (polio)

Microbial Loop

DOC Bacteria Higher Trophic Levels

Viruses

Lysis

Decay

CO2

Figure Adapted from Sawstrom, Viral Dynamics in the Microbial Loop

Viruses in the Marine EnvironmentThe estimated 1030 viruses in the ocean, if stretched end to end, would span farther than the nearest 60 galaxies.

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Characteristics of Aquatic Viruses

Most diverse and abundant component of the plankton community

Only a small portion of marine virus diversity has been isolated and described

Composition and structure are dependant on seasonality, the degree of stratification of the water column, and other factors related to geographic location.

Why Are They Important?

Marine Health – positive and negative influences

Global Carbon Cycle

Influence on Marine Health

Control of bacterial and algal populations Microbial Food Web & Nutrient cycling CO2 cycle Microbial Diversity

Role in Microbial Food Webs

Products of cell lysis: Macromolecules Cell organelles Virus particles

Influence on Structure and Diversity of Aquatic

Microbial Communities

Cell Predation Limiting Specific Bacteria and Phytoplankton Populations.

Lateral and Horizontal Gene Transfer

An Important Role in the Deep-Sea biogeochemical

cycles

Viral production in deep-sea benthic ecosystems worldwide is extremely high

Viral infections are responsible for the abatement of 80% of prokaryotic heterotrophic production

Viruses on the Sea Floor

Photo from Monterey Bay Aquarium Research Institute (MBARI)

Increasing Marine Stresses

Transfer of invasive, non-native, microbial constituents from one region to another

Pollution Outbreak of waterborne disease Loss of habitat Overharvesting

Implications for Future Research

The processes involved with with viruses and nutrient cycling need to be examined.

The effects of global warming have placed special emphasis on understanding the biogeochemical cycling of carbon and nitrogen.

Determination of how the physiology and ecology of planktonic organisms affects global carbon and nitrogen cycling may improve our ability to predict and perhaps remediate the ecological impacts of human related carbon and nitrogen release.

The Potential for New Discoveries

A marine virus has been found with a gigantic genome that contains compounds that might be used in anti-ageing and cancer-inhibiting therapies.

This virus is known to infect a marine algae species that is important in taking billions of tonnes of carbon dioxide from the atmosphere and is thought to control climate through the production of a gas (dimethyl sulfide) that helps form clouds.

Implications for Marine Management

Through cycles of infection, replication and host cell lysis, phages impact multiple pathways and processes involved in the population ecology and functioning of marine environments as a whole.

Scientists need to better understand the function of marine viruses in order to model the future effects of climate change and other global changes as well as to find new discoveries in medicine and microbiology.