Abundance and Distribution of Synechococcus spp. and Cyanophages in the Chesapeake Bay

Abstract

Despite the increasing knowledge of Synechococcus spp. and their co-occurring cyanophages in oceanic and coastal water, little is known about their abundance, distribution, and interactions in the Chesapeake Bay estuarine ecosystem. A 5-year interannual survey shows that Synechococcus spp. and their phages are persistent and abundant members of Chesapeake Bay microbial communities. Synechococcus blooms (10 6 cells ml ؊1 ) were often observed in summer throughout the Bay, contributing 20 to 40% of total phytoplankton chlorophyll a. The distribution of phycoerythrin-containing (PE-rich) Synechococcus cells appeared to mostly correlate with the salinity gradient, with higher abundances at higher salinities. Cyanophages infectious to Synechococcus were also abundant (up to 6 ؋ 10 5 viruses ml ؊1 by the most probable number assay) during summer months in the Bay. The covariation in abundance of Synechococcus spp. and cyanophages was evident, although the latitude of observed positive correlation varied in different years, mirroring the changing environmental conditions and therefore the host-virus interactions. The impacts of cyanophages on host Synechococcus populations also varied spatially and temporally. Higher phage-related Synechococcus mortality was observed in drought years. Virus-mediated host mortality and subsequent liberation of dissolved organic matter (DOM) may substantially influence oceanic biogeochemical processing through the microbial loop as well as the microbial carbon pump. These observations emphasize the influence of environmental gradients on natural Synechococcus spp. and their phage population dynamics in the estuarine ecosystem.

Diversity and temporal dynamics of Southern California coastal marine cyanophage isolates

“…Some of these studies also found that cyanophage abundances co-vary with cyanobacterial abundance and temperature (e.g. Waterbury & Valois 1993, Sandaa & Larsen 2006, Wang et al 2011, resembling the trend we observed here in Southern California (Fig. 3A).…”

“…3A) is similar to that of other studies in a variety of marine locations. In particular, the abundances of total viruses and cyanophages tend to be greatest in warmer seasons and/or lowest in the winter (Waterbury & Valois 1993, Jiang & Paul 1994, Suttle & Chan 1994, Cochran & Paul 1998, Marston & Sallee 2003, Millard & Mann 2006, Sandaa & Larsen 2006, Wang et al 2011, Parsons et al 2012. Some of these studies also found that cyanophage abundances co-vary with cyanobacterial abundance and temperature (e.g.…”

Influence of environmental changes on picophytoplankton and bacteria in Daya Bay, South China Sea

“…Synechococcus is more abundant in plume-influenced and coastal waters, while Prochlorococcus was dominant in the oligotrophic water of the Mississippi River plume and its adjacent waters (Liu et al 2004). Synechococcus cell density typically ranges from 10 2 to 10 5 cells mL -1 in temperate estuaries and often exceeds 10 6 cells mL -1 in subtropical regions (Wang et al 2011). Synechococcus is the most abundant group in various coastal ecosystems, including Chesapeake Bay (Wang et al 2011), San Francisco Bay (Ning et al 2000), and Florida Bay (Phlips et al 1999).…”

Contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle

“…Synechococcus maximum growth rates are comparable to or slighter faster than those of Prochlorococcus (25,26), with similar mechanisms of mortality (27,28). However, estimates of in situ specific growth rates are broader, between 1-6 d (29, 30), due to the varying environments Synechococcus occupies.…”