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The Toxicology Investigators Consortium 2024 Annual ReportNARA Subscribed
Tightly coupled carbon, nitrogen, and iron utilization by bacteria in the lower photic zone of the North Pacific Subtropical GyreNARA Subscribed
The metabolism of heterotrophic bacteria acts as a key control on the turnover of organic matter in the ocean. However, much remains unknown about how nutrient availability, particularly iron concentration, impacts bacterial growth. In the dimly lit waters of the lower photic and upper mesopelagic zones, the attenuation of sinking particulate flux is intense, due in part to remineralization by heterotrophic bacteria. In the No...
Gross oxygen production and microbial community respiration in the oligotrophic oceanNARA Subscribed
Uncertainties in the temporal and spatial patterns of marine primary production and respiration limit our understanding of the ocean carbon (C) cycle and our ability to predict its response to environmental changes. Here we present a comprehensive time‐series analysis of plankton metabolism at the Hawaii Ocean Time‐series program site, Station ALOHA, in the North Pacific Subtropical Gyre. Vertical profiles of gross oxygen prod...
Patterns of siderophore production and utilization at Station ALOHA from the surface to mesopelagic watersNARA Subscribed
The North Pacific subtropical gyre is a globally important contributor to carbon uptake despite being a persistently oligotrophic ecosystem. Supply of the micronutrient iron to the upper ocean varies seasonally to episodically, and when coupled with rapid biological consumption, results in low iron concentrations. In this study, we examined changes in iron uptake rates, along with siderophore concentrations and biosynthesis po...
The Toxicology Investigators Consortium 2023 Annual ReportNARA Subscribed
Trophic strategies of picoeukaryotic phytoplankton vary over time and with depth in the North Pacific Subtropical GyreNARA Subscribed
In oligotrophic oceans, the smallest eukaryotic phytoplankton are both significant primary producers and predators of abundant bacteria such as Prochlorococcus . However, the drivers and consequences of community dynamics among these diverse protists are not well understood. Here, we investigated how trophic strategies along the autotrophy‐mixotrophy spectrum vary in importance over time and across depths at Station ALOHA in t...
Mixing‐driven changes in distributions and abundances of planktonic microorganisms in a large, oligotrophic lakeNARA Subscribed
Temperate lakes experience variation in mixing and stratification that affects the distributions, activities, abundances, and diversity of plankton communities. We examined temporal and vertical changes in the composition of planktonic microorganisms (including Bacteria and Archaea) in oligotrophic Flathead Lake, Montana. Using a combination of approaches that included 16S rRNA gene sequencing and flow cytometric determination...
Out of sight, but not out of season: Nitrifier distributions and population dynamics in a large oligotrophic lakeNARA Subscribed
Nitrification is an important control on the form and distribution of nitrogen in freshwater ecosystems. However, the seasonality of nitrogen pools and the diversity of organisms catalyzing this process have not been well documented in oligotrophic lakes. Here, we show that nitrogen pools and nitrifying organisms in Flathead Lake are temporally and vertically dynamic, with nitrifiers displaying specific preferences depending o...
The Toxicology Investigators Consortium 2022 Annual ReportNARA Subscribed
Dinitrogen (N 2 ) fixation is carried out by specialized microbes, called diazotrophs, and is a major source of nitrogen supporting primary production in oligotrophic oceans. One of the best-characterized diazotroph habitats is the North Pacific Subtropical Gyre (NPSG), where warm, chronically N-limited surface waters promote year-round N 2 fixation. At Station ALOHA (A Long-Term Oligotrophic Habitat Assessment) in the NPSG, N...
Revisiting the growth rate hypothesis: Towards a holistic stoichiometric understanding of growthNARA Subscribed
The growth rate hypothesis (GRH) posits that variation in organismal stoichiometry (C:P and N:P ratios) is driven by growth‐dependent allocation of P to ribosomal RNA. The GRH has found broad but not uniform support in studies across diverse biota and habitats. We synthesise information on how and why the tripartite growth‐RNA‐P relationship predicted by the GRH may be uncoupled and outline paths for both theoretical and empir...
We examined variability in the euphotic zone (0–175 m) picoeukaryotic community based on time‐series observations (2011–2013) at Station ALOHA in the North Pacific Subtropical Gyre. By sampling over scales ranging from daily to approximately monthly over 2.25 years, we evaluated the resilience of the picoeukaryotic community to seasonal‐ to episodic‐scale physical disturbances, such as convective mixing and mesoscale processes...
Production and diversity of microorganisms associated with sinking particles in the subtropical North Pacific OceanNARA Subscribed
Sinking particulate organic matter controls the flux of carbon (C) from the surface ocean to the deep sea. Microorganisms actively colonize particles, but the extent to which microbial metabolism influences particle export remains uncertain. We conducted experiments to quantify rates of bacterial production (derived based on 3 H‐leucine incorporation) and dark C‐fixation (based on 14 C‐bicarbonate assimilation) associated with...
Bacteria and archaea are key contributors to deep-sea biogeochemical cycles and food webs. The disruptions these microbial communities may experience during and following polymetallic nodule mining in the Clarion-Clipperton Zone (CCZ) of the North Pacific Ocean could therefore have broad ecological effects. Our goals in this synthesis are to characterize the current understanding of biodiversity and biogeography of bacteria an...
Mesoscale eddies, prominent physical processes in the stratified ocean gyres, affect community composition and metabolic rates of both phytoplankton and heterotrophic bacterioplankton (free‐living bacterial and archaeal) communities. We hypothesized that in situ differences in organic matter production would predispose bacterioplankton communities from cyclonic vs. anticyclonic eddies toward metabolic capabilities better suite...