Lysogenic and lytic viral production in marine microbial communities

It is now well established that viruses are an abundant component of marine ecosystems and they are being increasingly recognised and accepted as important contnbutors to element cycling within the microbial loop. However, some of the key questions regarding the ecological significance of viruses in the marine environment still remain largely unanswered. Thus, particular interest is currently focused on the extent to which lytic production or lysoyeny predominates and the nature of factors in the marine environment, particularly nutrient availability and mult~plicity of .infection (MOI), which might influence the lysisflysogeny 'decision' The present evidence is still insufficient to unambiguously assess the relative ecological significance of lysogeny versus lysis and progress in this area will rely on the development and application of new techniques. This review attempts to collect recent information relating to this central question, focusing particularly on those viruses which infect the bacterioplankton and nanoand picophytoplankton.