title: Cyanobacterial distributions along a physico-chemical gradient in the Northeastern Pacific Ocean.
abstract: The cyanobacteria Prochlorococcus and Synechococcus are important marine primary producers. We explored their distributions and covariance along a physico-chemical gradient from coastal to open ocean waters in the Northeastern Pacific Ocean. An inter-annual pattern was delineated in the dynamic transition zone where upwelled and eastern boundary current waters mix, and two new Synechococcus clades, Eastern Pacific Clade (EPC) 1 and EPC2, were identified. By applying state-of-the-art phylogenetic analysis tools to bar-coded 16S amplicon datasets, we observed higher abundance of Prochlorococcus high-light I (HLI) and low-light I (LLI) in years when more oligotrophic water intruded farther inshore, while under stronger upwelling Synechococcus I and IV dominated. However, contributions of some cyanobacterial clades were proportionally relatively constant, e.g. Synechococcus EPC2. In addition to supporting observations that Prochlorococcus LLI thrive at higher irradiances than other LL taxa, the results suggest LLI tolerate lower temperatures than previously reported. The phylogenetic precision of our 16S rRNA gene analytical approach and depth of bar-coded sequencing also facilitated detection of clades at low abundance in unexpected places. These include Prochlorococcus at the coast and Cyanobium-related sequences offshore, although it remains unclear whether these came from resident or potentially advected cells. Our study enhances understanding of cyanobacterial distributions in an ecologically important eastern boundary system.
authors.affiliation: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd, Moss Landing, CA, 95039, USA.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Sudek
authors.affiliation: Exobiology Branch, NASA Ames Research Center, MS 239-4, Moffett Field, CA, 94035, USA.
authors.forename: R Craig
authors.initials: RC
authors.lastname: Everroad
authors.affiliation: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd, Moss Landing, CA, 95039, USA.
authors.forename: Alyssa-Lois M
authors.initials: AL
authors.lastname: Gehman
authors.affiliation: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd, Moss Landing, CA, 95039, USA.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Smith
authors.affiliation: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd, Moss Landing, CA, 95039, USA.
authors.forename: Camille L
authors.initials: CL
authors.lastname: Poirier
authors.affiliation: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd, Moss Landing, CA, 95039, USA.
authors.forename: Francisco P
authors.initials: FP
authors.lastname: Chavez
authors.affiliation: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd, Moss Landing, CA, 95039, USA.|Integrated Microbial Biodiversity Program, Canadian Institute for Advanced Research, Toronto, ON, M5G 1Z8, Canada.
authors.forename: Alexandra Z
authors.initials: AZ
authors.lastname: Worden
mesh_terms: D044822:Biodiversity; D010140:Pacific Ocean; D010802:Phylogeny; D048929:Prochlorococcus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*; D046940:Synechococcus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D012336:RNA, Ribosomal, 16S