A5031918003- Marine and coastal ecosystems
- Marine Biology and Ecology Research
- Microbial Community Ecology and Physiology
- Geochemistry and Elemental Analysis
- Diatoms and Algae Research
- Geology and Paleoclimatology Research
- Oceanographic and Atmospheric Processes
- Paleontology and Stratigraphy of Fossils
- Methane Hydrates and Related Phenomena
- Marine and fisheries research
- Isotope Analysis in Ecology
- Silicon Effects in Agriculture
- Marine Bivalve and Aquaculture Studies
- Molecular Junctions and Nanostructures
- Atmospheric and Environmental Gas Dynamics
- Marine and coastal plant biology
- Marine and environmental studies
- Geological Studies and Exploration
- Per- and polyfluoroalkyl substances research
- Cold Atom Physics and Bose-Einstein Condensates
- Aquatic Ecosystems and Phytoplankton Dynamics
- Food Industry and Aquatic Biology
- Ocean Acidification Effects and Responses
- Gold and Silver Nanoparticles Synthesis and Applications
- Coral and Marine Ecosystems Studies
University of South Alabama
2016-2025
Dauphin Island Sea Lab
2016-2025
University of Nevada, Reno
2024
Louisiana Department of Natural Resources
2024
Social and Scientific Systems (United States)
2022
Oceanography Society
2018
University of California, Santa Barbara
2009-2017
Oregon State University
2008-2010
Long Island University
2005
University of Florida
1997
Abstract The spring diatom bloom in the Arctic Ocean accounts for significant annual primary production leading to most rapid drawdown of water-column p CO 2 . Late-winter waters Atlantic & Subarctic Provinces (AASP) have lower silicic acid concentrations than nitrate, which suggests blooms may deplete Si before N. Here we test a facet hypothesis that limitation terminates AASP and sinking senescent dead diatoms helps drive carbon sequestration. During 6-week study, bloomed progressively...
Nutrient dynamics, phytoplankton rate processes, and export were examined in a frontal region between an anticyclone pair of cyclones 120 km off the coast southern California Current System (sCCS). Low silicic acid: nitrate ratios (Si:N) high to iron (N:Fe) characteristic Fe-limiting conditions sCCS associated with northern cyclone transition zone anticyclone. Phytoplankton growth low-Si:N, high-N:Fe waters responded strongly added Fe, confirming limitation by Fe diatom-dominated community....
Abstract. Diatoms are generally the dominant contributors to Arctic Ocean spring bloom, which is a key event in regional food webs terms of capacity for secondary production and organic matter export. Dissolved silicic acid an obligate nutrient diatoms has been declining European since early 1990s. The lack silicon cycling information precludes understanding consequences such changes diatom productivity during bloom. This study communicates results from cruise around Svalbard, reports first...
Biogeochemical cycling of silicon (Si) in the Barents Sea is under considerable pressure from physical and chemical changes, including dramatic warming sea ice retreat, together with a decline dissolved silicic acid (DSi) concentrations Atlantic inflow waters since 1990. Associated changes community composition phytoplankton blooms will alter material comprising depositional flux, which subsequently influence recycling processes at within seafloor. In this study we assess predominant...
The summertime North Pacific subtropical gyre has widespread phytoplankton blooms between Hawaii and the front (∼30°N) that appear as chlorophyll (chl) increases in satellite ocean color data. Nitrogen-fixing diatom symbioses (diatom-diazotroph associations: DDAs) often increase 102–103 fold these contribute to elevated export flux. In 2008 2009, two cruises targeted examine DDA species abundance, concentration, biogenic silica hydrography. Generalized observations occur when mixed layer...
Summary A mix of adaptive strategies enable diatoms to sustain rapid growth in dynamic ocean regions, making one the most productive primary producers world. We illustrate such strategy off coastal California that facilitates continued, high, cell division rates despite silicic acid stress. Using a fluorescent dye measure single‐cell diatom silica production rates, silicification (silica per unit area) and we show decrease maintain rate when silicon concentration limits rates. While this...
Abstract In the offshore waters of Southern California, submesoscale processes associated with fronts may stimulate phytoplankton blooms and lead to biomass shifts at multiple trophic levels. Here we report results a study on cycling biogenic silica (bSiO 2 ) estimates contributions diatoms primary new production in water masses adjacent (i.e., coastal or oceanic) within an front California Current Ecosystem (CCE). The oceanic were sampled cyclonic anticyclonic eddies, respectively, frontal...
Phytoplankton cellular elemental quotas are important for evaluating the coupling of nutrient cycles and assessing limitation in ocean. While cell element have been shown to vary response growth conditions (e.g., light, supply), an overriding trait is size biovolume. Allometric relationships lacking data phytoplankton grown under polar temperature <5oC); limited field using single-cell stoichiometry measurements diatoms may significantly different allometry versus low-latitude counterparts....
Abstract Advances in situ imaging allow enumeration of abundant populations large Rhizarians that compose a substantial proportion total mesozooplankton biovolume. Using quasi‐Lagrangian sampling scheme, we quantified the abundance, vertical distributions, and sinking‐related mortality Aulosphaeridae, an family Phaeodaria California Current Ecosystem. Inter‐cruise variability was high, with average concentrations at depth maximum abundance ranging from < 10 to > 300 cells m −3 ,...
We investigated standing stocks and grazing rates of mesozooplankton assemblages in the Costa Rica Dome (CRD), an open-ocean upwelling ecosystem eastern tropical Pacific. While phytoplankton biomass CRD is dominated by picophytoplankton (<2-µm cells) with especially high concentrations Synechococcus spp., we found (∼5 g dry weight m-2) impact (12-50% integrated water column chlorophyll a), indicative efficient food web transfer from primary producers to higher levels. In contrast relative...
Abstract In marine ecosystems, many planktonic organisms precipitate biogenic silica (bSiO 2 ) to build silicified skeletons. Among them, giant siliceous rhizarians (>500 μm), including Radiolaria and Phaeodaria, are important contributors oceanic carbon pools but little is known about their contribution the cycle. We report first analyses of phaeodarians bSiO export in California Current Ecosystem. measured content single rhizarian cells ranging size from 470 3,920 μm developed...
Upper water column biogenic silica (bSiO 2 ) at the Bermuda Atlantic Time‐series Study (BATS) site in western Sargasso Sea was measured biweekly to monthly from 1989 through 2003, and changes on four distinct timescales were observed. Mesoscale physical features, such as eddies, occasionally increase vertically integrated bSiO upper 120 m (∫bSiO by an order of magnitude or more (this degree enhancement observed only 5 217 total profiles). There is a strong seasonal cycle ∫bSiO , with maximum...
Six clones of the marine cyanobacterium Synechococcus , representing four major clades, were all found to contain significant amounts silicon in culture. Growth rate was unaffected by silicic acid, Si( OH ) 4 concentration between 1 and 120 μM suggesting that lacks an obligate need for (Si). Strains contained two pools Si: aqueous soluble insoluble pool. Soluble pool sizes correspond estimated intracellular dissolved Si concentrations 2–24 mM, which would be thermodynamically unstable...
Abstract Picocyanobacteria in the Sargasso Sea accumulate significant amounts of Si, a finding which questions how we interpret previous regional measurements biogenic silica (bSi) production and role diatoms open ocean. The picoplankton (<3 μm cells) contributed measurable, at times significant, proportion both total bSi standing stock its rate production. 100 m integrated <3 size fraction averaged 14% 16%, respectively, total. At some stations, specific rates cells were up to...
Abstract Many studies use sedimentary biogenic silica (bSiO 2 ) stable isotopes (e.g., δ 30 Si) as paleoproxies but neglect signals from other reactive SiO phases. We quantified Si for multiple pools in coastal river‐plume sediments, revealing up to −5‰ difference between acid‐leachable and alkaline‐digestible amorphous . Thus, previous have missed valuable information on early diagenetic products and, cases where sediments were not cleaned, potentially biased bSiO values. Acid‐leachable Si,...