Understanding and modeling microbial responses and feedbacks to climate change is hampered by a lack of a framework in the pelagic environment by which to link local mechanism to large scale patterns. Where terrestrial ecology draws from landscape theory and practice to address issues of scale, the pelagic seascape concept...
Fluctuations in one system affect adjacent systems; mechanistic understanding of linkages helps conservation efforts be more effective by focusing on influential species and areas that facilitate connections between ecosystems. This study explored marine-derived nutrient inputs to adjacent terrestrial communities. We quantified wrack (seaweed and other organic matter) deposition at sites...
Biological di-nitrogen (N₂) fixation is a key process in open-ocean ecosystems, where the new nitrogen (N) provided by marine diazotrophs can support a large fraction of primary productivity and carbon (C) drawdown. Recent laboratory studies have shown that elevated pCO₂ enhances the rate of N₂ fixation by select laboratory isolates...
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RicardoM. Letelier
Biological di-nitrogen (N2) fixation is a key process in open-ocean
The biological transformation of dinitrogen gas (N2) into combined forms(termed N2 fixation) by certain genera of oceanic cyanobacteria represents the largest incoming flux of nitrogen to the global ocean. As such, biological nitrogen fixation
plays a significant role in the regulation of oceanic productivity and the export of
carbon and...
The North Pacific subtropical gyre (NPSG), once considered to be a biological desert due to low primary production (PP) and its associated variability, has been found more productive and variable than previously thought. The environmental conditions controlling this relatively high PP variability are yet to be elucidated, despite important implications...
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Mark R. Abbott, RicardoM. Letelier
The North Pacific subtropical gyre (NPSG), once
Our view of phytoplankton has historically revolved around their inability to
control their location in space. The term phytoplankton itself underscores this
particular difference between phytoplankton and their sessile terrestrial counterparts.
Yet there are other differences between land plants and the phytoplankton that are
perhaps equally important, beyond this sessile-planktonic...
Under conditions of fixed N-limitation, as with most oligotrophic systems, the process of biological N₂ fixation (diazotrophy) is favored, provided the necessary trace elements and vitamins are sufficient. Despite the well understood contributions of N₂
fixation in oligotrophic regions, the nutritional and ecological controls of marine diazotrophs have not been...
In ecological restoration, species that are sown to increase the native plant
diversity range in establishment ability. Some species readily establish, while others
rarely do. This study set out to investigate some of the potential processes influencing
species establishment, as well as the traits that are associated with the success...
Deep mixing events in the ocean’s surface layer act as physical drivers of carbon export by detraining dissolved and particulate organic matter, including surface phytoplankton communities, to depth. Once removed from the sunlit surface ocean environment, phytoplankton accumulation rates are dependent on the relative contributions of loss processes, such as...
We present a new nitrogen isotope model incorporated into the three-dimensional ocean component of a global Earth System Climate Model designed for millennial timescale simulations. The model includes prognostic tracers for the stable nitrogen isotopes, ¹⁴N and ¹⁵N, in the nitrate (NO₃ˉ), phytoplankton, zooplankton, and detritus variables of the marine...
Iron (Fe) is an important limiting nutrient that can affect the rate of ocean primary production because it is required by phytoplankton as an enzymatic cofactor in photosynthesis, nitrogen fixation, and other essential metabolic functions. Most Fe reaches the surface of the open ocean via atmospheric dust deposition, which is...
The concentrations of filamentous diazotroph Trichodesmium spp., present as free trichomes and in colonial assemblages, were measured at approximately monthly intervals at Stn ALOHA (22°45'N, 158°00'W) between October 1989 and December 1992. The average abundance of filaments in the upper 45 m of the water column was highly variable ranging...
The potential role of the diazotrophic cyanobacterium Trichodesmium spp. In nitrogen and phosphorus dynamics of the euphotic zone of the North Pacific subtropical gyre was investigated as one component of the Hawaii Ocean Time-series (HOT) program. Experiments were conducted with natural samples collected at Stn ALOHA (22° 45’ N, 158°...
The euphotic zone below the deep chlorophyll maximum layer (DCML) at Station ALOHA (a long-term oligotrophic habitat assessment; 22º45′N, 158º00′W) transects the nearly permanently stratified upper thermocline. Hence, seasonal changes in solar radiation control the balance between photosynthesis and respiration in this lightlimited region. Combining profiles of radiance reflectance, algal...
Based on a long-term set of observations and measurements at a station in the subtropical North Pacific Ocean, it now appears that contemporaneous rates of primary production in low-nutrient open ocean regions and perhaps in the ocean as a whole may be greater than had been considered in field studies...
Summertime wind stress along the coast of the northwestern United States typically exhibits intraseasonal oscillations (ISOs) with periods from ≈15 to 40 days, as well as fluctuations on the 2- to 6-day “weather-band” and 1-day diurnal time scales. Coastal upwelling of cool, nutrient-rich water is driven by extended periods of...
Variability of solar-induced (natural) fluorescence and chlorophyll were measured on scales of hours to weeks in the upper layer of a cyclonic eddy located south of the Antarctic Polar Front using a free-floating drifter. The fluorescence signal was analyzed both in terms of chlorophyll concentration and as an indicator of...
Ocean Acidification (OA) has emerged as a major threat to marine ecosystems, particularly regarding calcifying organisms. A growing body of literature describing laboratory investigations into pH stress indicates broadly deleterious effects for calcifiers, but responses vary greatly across taxa and can be influenced by variations in other environmental characteristics. Scaling...
Secondary metabolites (SMs) play an integral role in the life history of most fungal species. Fungal metabolomic studies provide insights into how fungi perform certain ecological functions, how they compete and interact with other organisms, and the breadth of fungal chemodiversity. Fungal SMs have also been utilized for a variety...