Johnson ZI, Zinser ER, Coe AC, McNulty NP, Woodward EMS, Chisholm SW.. Niche partitioning among Prochlorococcus ecotypes along ocean-scale environmental gradients. Science 311: 1737-1740

Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 15 Vassar Street 48-419, Cambridge, MA 02139, USA.
Science (Impact Factor: 33.61). 04/2006; 311(5768):1737-40. DOI: 10.1126/science.1118052
Source: PubMed


Prochlorococcus is the numerically dominant phytoplankter in the oligotrophic oceans, accounting for up to half of the photosynthetic biomass and production in some regions. Here, we describe how the abundance of six known ecotypes, which have small subunit ribosomal RNA sequences that differ by less than 3%, changed along local and basin-wide environmental gradients in the Atlantic Ocean. Temperature was significantly correlated with shifts in ecotype abundance, and laboratory experiments confirmed different temperature optima and tolerance ranges for cultured strains. Light, nutrients, and competitor abundances also appeared to play a role in shaping different distributions.

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    • "erged independently in both genera . Inter - estingly , the shift from warm - water Synechococcus clades ( II , III and X ) to cold - water clades ( I and IV ) occurs at ~ 21 °C in the open ocean , similar to the thresholds for the shifts in dominance of warm - adapted HLII to cold - adapted HLI Prochlorococcus ecotypes ( Supplementary Figure S7 ; Johnson et al . , 2006 ) . Parallel evolution of ecotypes may be facilitated by the horizontal transfer of adaptive genes , from both other marine bacteria and among picocyanobacteria ( Kettler et al . , 2007 ; Dufresne et al . , 2008 ; Scanlan et al . , 2009 ; Zhaxybayeva et al . , 2009 ) . Such gene transfer is at least partially mediated by cyanophage , wh"
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    ABSTRACT: Marine picocyanobacteria, comprised of the genera Synechococcus and Prochlorococcus, are the most abundant and widespread primary producers in the ocean. More than 20 genetically distinct clades of marine Synechococcus have been identified, but their physiology and biogeography are not as thoroughly characterized as those of Prochlorococcus. Using clade-specific qPCR primers, we measured the abundance of 10 Synechococcus clades at 92 locations in surface waters of the Atlantic and Pacific Oceans. We found that Synechococcus partition the ocean into four distinct regimes distinguished by temperature, macronutrients and iron availability. Clades I and IV were prevalent in colder, mesotrophic waters; clades II, III and X dominated in the warm, oligotrophic open ocean; clades CRD1 and CRD2 were restricted to sites with low iron availability; and clades XV and XVI were only found in transitional waters at the edges of the other biomes. Overall, clade II was the most ubiquitous clade investigated and was the dominant clade in the largest biome, the oligotrophic open ocean. Co-occurring clades that occupy the same regime belong to distinct evolutionary lineages within Synechococcus, indicating that multiple ecotypes have evolved independently to occupy similar niches and represent examples of parallel evolution. We speculate that parallel evolution of ecotypes may be a common feature of diverse marine microbial communities that contributes to functional redundancy and the potential for resiliency.The ISME Journal advance online publication, 24 July 2015; doi:10.1038/ismej.2015.115.
    No preview · Article · Jul 2015 · The ISME Journal
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    • "(1) Light modulation: The Arabian Sea is dominated by two ecotypes of Prochlorococcus; the high light (HL) and the low light (LL) with the latter dominating the hypoxic– suboxic environment in the Arabian Sea (Goericke et al., 2000), which is consistent with our observation. Johnson et al. (2006) showed this may lead to niche partitioning among Prochlorococcus along the ocean scale. Average light received the LL populations in the Arabian Sea is <0.1% I 0 (Goericke et al., 2000). "
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    ABSTRACT: Physical forcing can replenish nutrients within the mixed layer by convective mixing or via upwelling. Conventional wisdom holds this enrichment fuels phytoplankton growth, for example ventilation of subsurface water during winter monsoon is known to enhance primary productivity in the northern Arabian Sea. One important numerically dominant phytoplankton known to have ecological niche in the ocean is Prochlorococcus. In the Arabian Sea, they occur in oligotrophic surface water and below the oxycline representing two different light and biogeochemical regimes. Here we show convective mixing in the northern Arabian Sea inhibits Prochlorococcus growth owing to change in physical environment. Pigment observations carried out during early and peak winter monsoon revealed contrasting picoplankton distribution. Divinyl chlorophyll a (a marker for Prochlorococcus) which was the most abundant picoplankton pigment during early winter monsoon was not detected with the onset of winter convection covarying with high nutrients in the surface water. We propose two possible mechanisms for such sudden disappearance which involves changes in light and biogeochemical regimes. This physico-chemical control could be critical for their existence but not limited to and can play an important role in regions experiencing such phenomenon. We also highlight the linkages between Prochlorococcus succession and basin scale dynamcis from the Arabian Sea which hitherto remains poorly understood.
    Full-text · Article · Jul 2015 · Progress In Oceanography
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    • "They are abundant and diverse in freshwater lakes, estuaries, coastal, and open oceans. Prochlorococcus and Synechococcus are the dominant picocyanobacteria in most oceanic waters (Scanlan 2003, Johnson et al. 2006, Scanlan et al. 2009). Compared to the open ocean, much less is known about the picocyanobacteria in estuaries which are subjected to marine and riverine influences causing complex and variable hydrological conditions. "
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    ABSTRACT: Picocyanobacteria are major primary producers in the ocean, especially in the tropical or subtropical oceans or during warm seasons. Many “warm” picocyanobacterial species have been isolated and characterized. However, picocyanobacteria in cold environments or cold seasons are much less studied. In general, little is known about the taxonomy and ecophysiology of picocyanobacteria living in the winter. In this study, 17 strains of picocyanobacteria were isolated from Chesapeake Bay, a temperate estuarine ecosystem, during the winter months. These winter isolates belong to five distinct phylogenetic lineages, and are distinct from the picocyanobacteria previously isolated from the warm seasons. The vast majority of the winter isolates were closely related to picocyanobacteria isolated from other cold environments like Arctic or subalpine waters. The winter picocyanobacterial isolates were able to maintain slow growth or prolonged dormancy at 4°C. Interestingly, the phycoerythrin-rich strains outperformed the phycocyanin-rich strains at cold temperature. In addition, winter picocyanobacteria changed their morphology when cultivated at 4°C. The close phylogenetic relationship between the winter picocyanobacteria and the picocyanobacteria living in high latitude cold regions indicates that low temperature locations select specific ecotypes of picocyanobacteria.This article is protected by copyright. All rights reserved.
    Full-text · Article · Jun 2015 · Journal of Phycology
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