Virioplankton distribution in the tropical western Pacific Ocean in the vicinity of a seamount

Abstract

The shallow Caroline Seamount is located in the tropical western Pacific Ocean. Its summit is 57 m below the surface and penetrates the euphotic zone. Therefore, it is ideal for the study of the influence of seamount on plankton distribution. Here, virioplankton abundance and distribution were investigated by flow cytometry (FCM) in the Caroline Seamount in August and September 2017. The total abundance of virus‐like particles (VLP) was in the range of 0.64 × 106–18.77 × 106 particles/ml and the average was 5.37 ± 3.75 × 106 particles/ml. Three to four distinct viral subclusters with similar side scatter but different green fluorescence intensities were identified. Above the deep chlorophyll maximum (DCM), two medium fluorescence virus (MFV) subclusters were discriminated. Between the DCM and the deeper layers, only one MFV subcluster was resolved. In general, low fluorescence viruses (LFV) comprised the most abundant subclusters. In the 75–150 m water column, however, the MFV abundance was higher than the LFV abundance. High fluorescence viruses (HFV) constituted the least abundant subcluster throughout the entire water column. Virioplankton abundance was significantly enhanced at the seamount stations. Environmental factors including water temperature and nitrate concentration were the most correlated with the variation in virioplankton abundance at the seamount stations. Interactions between shallow seamounts and local currents can support large virus standing stocks, causing a so‐called indirect “seamount effect” on the virioplankton.

Planktonic ciliate trait structure variation over Yap, Mariana, and Caroline seamounts in the tropical western Pacific Ocean

“…The ciliate vertical distribution patterns were the same over three seamounts with abundance peaks in surface and DCM layers. The food items of the ciliate might be the reason for the two groups: Prochlorococcus and picoeukaryotes had maximum abundance in DCM, Synechococcus and heterotrophic bacteria had maximum abundance in upper 50-m depth (Zhao et al, 2017(Zhao et al, , 2020.…”

Habitat types and megabenthos composition from three sponge-dominated high-Arctic seamounts

“…This phenomenon is known as the ‘seamount oasis hypothesis’ 9 that asserts that benthic invertebrates occur in higher densities and biomasses on seamounts than in other habitats in the deep sea 9 . Seamounts can also influence the overlying water column and affect the microbial community 10,11 , phytoplankton 12 , zooplankton 13 , and ultimately large fish 1 , a phenomenon known as the ‘seamount effect’ 13 .…”

New Insights Into the Virus-to-Prokaryote Ratio (VPR) in Marine Sediments

“…Fluorescence microscopy (EFM) and flow cytometry (FCM) are both common methods used to enumerate viruses and prokaryotes in marine samples. Compared with EFM, FCM is more sensitive to fluorescent stain and less influenced by the skills of the operators (Brussaard, 2004) and thus has been commonly used for counting viruses and prokaryotes in water samples (e.g., Marie et al, 1999;Chen et al, 2001;Zhao et al, 2020). However, FCM is not widely applied for the determination of sediment VA and PA. To avoid instrument clogging, sediment samples must be centrifuged before determined by FCM, such a process could lead to underestimation and higher coefficient of variation of the enumeration (Glud and Middelboe, 2004;Siem-Jørgensen et al, 2008;Dai, 2012;Frossard et al, 2016).…”