Project: Discovery of viruses infecting marine Copepoda

(Adapted from the NSF Award Abstract)

Mesozooplankton are critical components of marine food webs as the primary consumers of phytoplankton, as prey for upper trophic level predators including commercially important fish, and by mediating carbon transfer from the atmosphere to the ocean interior through fecal matter deposition. Thus, the factors that control population dynamics of zooplankton are critical to understanding the structure and function of marine food webs. Two decades of research on marine viruses have demonstrated their profound effects on all levels of marine life from bacteria to whales. The majority of marine virus studies have focused on infection of microorganisms, particularly heterotrophic prokaryotes and eukaryotic phytoplankton. Despite the ecological importance of zooplankton, virtually nothing is known about the impact of viruses on the most abundant zooplankton group - the copepods.

This project will prospect for novel viruses in Acartia tonsa, a dominant calanoid copepod in Tampa Bay, Florida using metagenomic sequencing approaches. The viral load, prevalence, and environmental reservoirs for selected newly identified viruses will then be examined using quantitative PCR. This study will present the biological oceanography community with novel information on the diversity and prevalence of viruses in copepods. An increased understanding of the types of viruses infecting mesozooplankton will increase knowledge of viral diversity in the oceans and provide sequence information on a poorly-constrained genetic pool. The long-term goal of this project is to understand the impact of viruses on zooplankton population dynamics as agents of mortality and, therefore, ultimately how viral infections affect food web interactions and biogeochemical cycling in the oceans. Determining the type of viruses present in copepods and the prevalence of these viruses are critical first steps in determining the role of viruses in zooplankton ecology. Understanding the role of viruses in mesozooplankton ecology will fill a major gap in knowledge of marine ecosystem dynamics, and has the potential to be transformative for oceanography.

No environmental metadata was collected as part of this study.

All sequence information associated with this study has been deposited into NCBI Genbank. The accession numbers for the two circoviruses detected are JF912805 and JQ837277. Additional metagenomic sequences have been deposited under accession nos. JY253391–JY253440).

All Quantitative PCR data obtained as part of this study has been published in peer-reviewed journals:

Dunlap, D.S., T.F.F. Ng, K. Rosario, J.G. Barbosa, A.M. Greco, M. Breitbart, I. Hewson (2013). Molecular and microscopic evidence of viruses in marine copepods.  Proceedings of the National Academy of Sciences of the USA, 110  1375.

Eaglesham JB, Hewson I (2013). Widespread detection of eukaryotic circular ssDNA viral genotypes in estuarine, coastal and open ocean net plankton.  Marine Ecology Progress Series, in press (doi: 10.3354/meps10575).