Resumen de Relative Contribution of Viral Lysis and Grazing to Bacterial Mortality in Tropical Coastal Waters of Peninsular Malaysia
We investigated the relative importance of viral lysis and heterotrophic nanoflagellate (HNF) grazing in bacterial mortality as part of a study to understand the microbial loop functioning in tropical waters of Straits of Malacca and South China Sea above the Sunda Shelf. Bacterial abundance ranged from 0.8 × 106 to 2.9 × 106 cells ml-1 and bacterial production ranged from 0.7 × 105 to 4.2 × 105 cells ml-1 hr-1. HNF and viral abundance ranged from 0.6 × 103 to 10.1 × 103 cells ml-1 and 0.3 × 107 to 1.4 × 107 virus particles ml-1, respectively. HNF grazing rates were from 1.1 × 104 to 16.8 × 104 cells ml-1 hr-1, whereas viral lysis rates ranged from 0.7 × 104 to 3.9 × 104 cells ml-1 hr-1. There was predator-prey coupling across the stations with both viral lysis and HNF grazing rates significantly correlated with bacterial production. HNF grazing accounted for 26.1% ± 14.6 of bacterial production, whereas viral lysis was 9.0% ± 3.5 of bacterial production. Bacterial mortality by both HNF and viruses averaged 35.5% ± 13.9, and was outpaced by bacterial production. Other loss factors, such as grazing by ciliates, sedimentation, benthic filter feeders, autolysis, or predatory bacteria, could be important.
