A5044941352- Marine and coastal ecosystems
- Microbial Community Ecology and Physiology
- Marine Biology and Ecology Research
- Isotope Analysis in Ecology
- Methane Hydrates and Related Phenomena
- Geology and Paleoclimatology Research
- Protist diversity and phylogeny
- Climate change and permafrost
- Environmental DNA in Biodiversity Studies
University of California, Santa Cruz
2016-2023
The microbial fixation of N2 is the largest source biologically available nitrogen (N) to oceans. However, it most energetically expensive N-acquisition process and believed inhibited when less forms, like dissolved inorganic N (DIN), are available. Curiously, cosmopolitan N2-fixing UCYN-A/haptophyte symbiosis grows in DIN-replete waters, but sensitivity their DIN unknown. We used stable isotope incubations, catalyzed reporter deposition fluorescence in-situ hybridization (CARD-FISH),...
Abstract. Marine diazotrophs convert dinitrogen (N2) gas into bioavailable nitrogen (N), supporting life in the global ocean. In 2012, first version of oceanic diazotroph database (version 1) was published. Here, we present an updated 2), significantly increasing number situ diazotrophic measurements from 13 565 to 55 286. Data points for N2 fixation rates, cell abundance, and nifH gene copy abundance have increased by 184 %, 86 809 respectively. Version 2 includes two new data sheets...
A recently described symbiosis between the metabolically streamlined nitrogen‐fixing cyanobacterium UCYN ‐A and a single‐celled eukaryote prymnesiophyte alga is widely distributed throughout tropical subtropical marine waters, thought to contribute significantly nitrogen fixation in these regions. Several sublineages have been defined based on nitrogenase ( nifH ) sequences. Due low abundances of global oceans, currently existing molecular techniques are limited for detecting quantifying...
From June to August 2018, the eruption of Kīlauea volcano on island Hawai'i injected millions cubic meters molten lava into nutrient-poor waters North Pacific Subtropical Gyre. The lava-impacted seawater was characterized by high concentrations metals and nutrients that stimulated phytoplankton growth, resulting in an extensive plume chlorophyll a detectable satellite. Chemical molecular evidence revealed this biological response hinged unexpectedly nitrate, despite negligible quantities...
Nitrogen (N2) fixation is a major source of nitrogen that supports primary production in the vast oligotrophic areas world's oceans. The Western Tropical South Pacific has recently been identified as hotspot for N2 fixation. In Noumea lagoon (New Caledonia), high abundances unicellular N2-fixing cyanobacteria group A (UCYN-A), coupled with daytime rates associated <10 μm size fraction, suggest UCYN-A may be an important diazotroph (N2-fixer) this region. However, little known about seasonal...
The availability of fixed nitrogen (N) is an important factor limiting biological productivity in the oceans. In coastal waters, high dissolved inorganic N concentrations were historically thought to inhibit dinitrogen (N2) fixation, however, recent N2 fixation measurements and presence N2-fixing UCYN-A/haptophyte symbiosis nearshore waters challenge this paradigm. We characterized contribution UCYN-A symbioses Southern California Current System (SCCS) by measuring bulk community single-cell...
The unicellular N 2 -fixing cyanobacteria UCYN-A live in symbiosis with haptophytes the Braarudosphaera bigelowii lineage. Maintaining symbioses between two partners requires tight coordination of multiple biological processes including cell growth and division and, case symbiosis, fixation symbiont photosynthesis host. In this system, it is thought that host supports high energetic cost fixation, both occur during light period. However, information on very limited difficult to obtain...
Dinitrogen (N 2 ) fixation is carried out by specialized microbes, called diazotrophs, and a major source of nitrogen supporting primary production in oligotrophic oceans. One the best-characterized diazotroph habitats North Pacific Subtropical Gyre (NPSG), where warm, chronically N-limited surface waters promote year-round N fixation. At Station ALOHA (A Long-Term Oligotrophic Habitat Assessment) NPSG, typically ascribed to conspicuous, filamentous cyanobacterial diazotrophs ( Trichodesmium...
Coastal and open ocean regions of the Western Tropical South Pacific have been identified as a hotspot N2 fixation. However, environmental factors driving temporal variability abundance, composition, activity diazotrophs are still poorly understood, especially during winter season. To address this, we quantified fixation rates abundance seven diazotroph phylotypes (UCYN-A1 symbiosis, UCYN-B, UCYN-C, Trichodesmium, Het-1, Het-2 Het-3) on monthly basis two full years (2012 to 2014) at four...