Response of the bacterioplankton composition to inorganic nutrient loading and phytoplankton in southern Korean coastal waters: A mesocosm study

Abstract

In Korean coastal waters (KCW), nutrient loading from the four major rivers usually peaks in summer, probably due to the large amount of water discharge in rainy seasons, but little is known about the responses of the bacterial community composition to inorganic nutrient loading. To gain deeper understanding of variations in marine microbial biodiversity and function with inorganic nutrient loading, a large‐scale mesocosm (1,000 L) experiment was conducted in southern KCW for 10 days in summer (July 27 through August 6, 2015) and the bacterioplankton community composition (BCC) was investigated using 16S rRNA amplicon pyrosequencing method. The bioassays established in the mesocosm were designed with the following each nutrient dosing treatments: nitrate (+N), phosphate (+P), and nitrate plus phosphate (+NP). Among the three treatments, the +NP and +N treatments exhibited the largest and second‐largest increases in phytoplankton abundance, respectively, whereas there was relatively less variation under the +P treatment. Enhanced growth of phytoplankton not only induced increases in pH and bacterial abundance (p < .05) but also led to changes in the BCC: the orders Flavobacteria, Micrococcales, Oceanospirillales, and Rhodobacterales exhibited increases in relative abundance, whereas Methylophilales, Puniceicoccales, SAR11, SAR116, and SAR86 showed a decreasing trend. Inorganic nutrients may directly contribute to variation in the BCC, as the relative abundance of Sphingobacteriales, containing members that undergo chemotaxis toward inorganic nutrients, was increased by the +N treatment. Given that these findings, changes in phytoplankton abundance due to nutrient addition may be the most crucial component resulting in variation in the BCC.

Response of bacterial communities (Marivita, Marinobacter, and Oceanicaulis) in the phycosphere to the growth of Phaeodactylum tricornutum in different inorganic nitrogen sources

“…By contrast, the abundance of certain Betaproteobacteria decreased due to competition for ammonium with phytoplankton (Christman et al, 2011). As a result, changes in phytoplankton abundance can influence variations in the phycosphere bacterial communities (Park et al, 2020), which is consistent with the findings of our study. Under nitrogen limitation, algae reached stability earlier (96h and 144h, Figure 1A).…”

“…These bacteria include attached and free-living bacteria (Seymour et al, 2017). Park et al (2020) discovered that the significant increase in phytoplankton abundance might be a key cause of the increase in bacterial abundance and changes in the communities along the southern Korean coast. Phytoplankton can secrete metabolites to provide nutrients for the phycosphere bacteria.…”

Rearing water microbiomes in white leg shrimp (Litopenaeus vannamei) larviculture assemble stochastically and are influenced by the microbiomes of live feed products

“…Phytoplankton is known to steer bacterial communities (Pinhassi et al ., 2004; Teeling et al ., 2016; Park et al ., 2020). Tang et al .…”

“…Phytoplankton is known to steer bacterial communities (Pinhassi et al, 2004;Teeling et al, 2016;Park et al, 2020). Tang et al (2020) compared cultivations with live and powdered algae and showed that the algae actively modulated the rearing water communities and increased cultivation performance.…”

Rearing water microbiomes in white leg shrimp (Litopenaeus vannamei) larviculture assemble stochastically and are influenced by the microbiomes of live feed products

“…Phytoplankton is known to steer bacterial communities (Pinhassi et al, 2004;Teeling et al, 2016;Park et al, 2020). Tang et al (2020) compared cultivations with live and powdered algae and showed that the algae actively modulated the rearing water microbiomes and increased cultivation performance.…”