Tight Coupling of Glaciecola spp. and Diatoms during Cold-Water Phytoplankton Spring Blooms

• Published in: Frontiers in microbiology Vol. 8; p. 27
• Main Authors: von Scheibner, Markus, Sommer, Ulrich, Jürgens, Klaus
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 19-01-2017
• Subjects: Microbiology; Glaciecola; spring bloom; phytoplankton; temperature; marine bacteria; CARD-FISH; Baltic Sea
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2017.00027

Early spring phytoplankton blooms can occur at very low water temperatures but they are often decoupled from bacterial growth, which is assumed to be often temperature controlled. In a previous mesocosm study with Baltic Sea plankton communities, an early diatom bloom was associated with a high relative abundance of
sequences (
), at both low (2°C) and elevated (8°C) temperatures, suggesting an important role for this genus in phytoplankton-bacteria coupling. In this study, the temperature-dependent dynamics of free-living
spp. during the bloom were analyzed by catalyzed reporter deposition fluorescence
hybridization using a newly developed probe. The analysis revealed the appearance of
spp. in this and in previous spring mesocosm experiments as the dominating bacterial clade during diatom blooms, with a close coupling between the population dynamics of
and phytoplankton development. Although elevated temperature resulted in a higher abundance and a higher net growth rate of
spp. (Q
∼ 2.2), their growth was, in contrast to that of the bulk bacterial assemblages, not suppressed at 2°C and showed a similar pattern at 8°C. Independent of temperature, the highest abundance of
spp. (24.0 ± 10.0% of total cell number) occurred during the peak of the phytoplankton bloom. Together with the slightly larger cell size of
, this resulted in a ∼30% contribution of
to total bacterial biomass. Overall, the results of this and previous studies suggest that
has an ecological niche during early diatom blooms at low temperatures, when it becomes a dominant consumer of phytoplankton-derived dissolved organic matter.