scholarly journals Viral lysis and nanoflagellate grazing as factors controlling diel variations of Synechococcus spp. summer abundance in coastal waters of Taiwan

2012 ◽  
Vol 66 (2) ◽  
pp. 159-167 ◽  
Author(s):  
AY Tsai ◽  
GC Gong ◽  
RW Sanders ◽  
KP Chiang ◽  
JK Huang ◽  
...  
Keyword(s):  
Coastal Waters ◽  
Viral Lysis ◽  
Diel Variations

The contribution of heterotrophic nanoflagellate grazing towards bacterial mortality in tropical waters: comparing estuaries and coastal ecosystems

2011 ◽  
Vol 62 (4) ◽  
pp. 414 ◽  
Author(s):  
Chui Wei Bong ◽  
Choon Weng Lee
Keyword(s):  
Coastal Waters ◽  
Bacterial Production ◽  
Trophic Status ◽  
Bacterial Abundance ◽  
Temperature Optimum ◽  
Viral Lysis ◽  
Tropical Waters ◽  
Order Of Magnitude ◽  
Heterotrophic Nanoflagellate ◽  
Straits Of Malacca

Heterotrophic nanoflagellate (HNF) grazing depends on both temperature and trophic status of an ecosystem. As most microbes already function at their temperature optimum in tropical waters, we hypothesised that HNF grazing rates would be higher in more productive sites such as estuaries than in less productive areas such as coastal waters. We sampled two estuaries and three coastal sites along the Straits of Malacca and the South China Sea near the Malaysia Peninsula. Bacterial abundance ranged 0.9–6.3 × 106 cells mL–1, whereas HNF abundance ranged 1.8–10.1 ×103 cells mL–1. Bacterial production ranged 1.1–12.7 × 105 cells mL–1 h–1, whereas HNF grazing rates were an order of magnitude lower at 1.0–78.5 × 104 cells mL–1 h–1. Bacterial abundance, net bacterial production and HNF grazing rates were higher in estuaries than coastal waters but HNF abundance did not differ between the two areas. Across all stations, HNF grazing rates increased with bacterial production, and accounted for ~33% of bacterial production. Our results suggest that in the tropical waters studied, there was a bacterial production–grazing imbalance. Other loss factors such as viral lysis, sedimentation or the presence of benthic filter feeders could account for this imbalance.

scholarly journals Is the Dilution Technique Underestimating the Picophytoplankton Growth Measurements?

2021 ◽  
Vol 9 (6) ◽  
pp. 628
Author(s):  
Pei-Chi Ho ◽  
Gwo-Ching Gong ◽  
Vladimir Mukhanov ◽  
An-Yi Tsai
Keyword(s):  
Flow Cytometry ◽  
Growth Rate ◽  
Mortality Rate ◽  
Phytoplankton Biomass ◽  
Grazing Rate ◽  
Dilution Technique ◽  
Coastal Regions ◽  
Short Term ◽  
Viral Lysis ◽  
Diel Variations

In oceanic communities, picophytoplankton often dominates phytoplankton biomass and productivity. Diel variations in picophytoplankton abundance and growth have been well documented. In the current study, we used flow cytometry to assess the short-term variations (3 h) of the abundance of the most dominant picophytoplankton, Synechococcus spp. and picoeukaryotes, in the coastal regions of northeastern Taiwan. To explore the change in growth and mortality rate in the daytime and over 24 h incubation, we performed a two-point modified dilution experiment for measuring growth, viral lysis, and nanoflagellate grazing rate. In this study, the growth rates of picoeukaryotes were 0.21 and 0.06 h−1, and those of Synechococcus spp. were 0.15 and 0.06 h−1 for daytime and 24 h incubation, respectively, and the values were higher at significant levels in the daytime than those for 24 h incubation. These growth rate values of picoeukaryote and Synechococcus spp. after incubation for 24 h were approximately underestimated at 71% and 55%, respectively. This finding suggests that estimates based on 24 h sampling may not accurately reflect the true growth rate of these populations on ecologically relevant timescales.

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