The particle size distribution (PSD) is a critical aspect of the oceanic ecosystem. Local variability in the PSD can be indicative of shifts in microbial community structure and reveal patterns in cell growth and loss. The PSD also plays a central role in particle export by influencing settling speed. Satellite-based...
Time-series observations are critical to understand the structure, function, and dynamics of marine ecosystems. The Hawaii Ocean Time-series program has maintained near-monthly sampling at Station ALOHA (22°45′N, 158°00′W) in the oligotrophic North Pacific Subtropical Gyre (NPSG) since 1988 and has identified ecosystem variability over seasonal to interannual timescales. To further...
During the summer of 2012, we used laser diffractometry to investigate the temporal and vertical variability of the particle size spectrum (1.25–100 µm in equivalent diameter) in the euphotic zone of the North Pacific Subtropical Gyre. Particles measured with this optical method accounted for ∼40% of the particulate carbon stocks...
Laboratory culture experiments were performed to establish the range of growth conditions where ¹³C labeling of di- and tri-unsaturated C₃₇ methyl ketones yields reliable growth rates for alkenone-producing algae. Results document that even at low growth rates and short time intervals, ¹³C labeling of the di-unsaturated C₃₇ alkenone provides reasonable...
Nitrate concentrations, chlorophyll a (Chl a) fluorescence, radiance, salinity, and
temperature were measured on the Hawaii Air-Sea Logging Experiment, A Long-Term
Oligotrophic Habitat Assessment (HALE ALOHA) mooring located near the Hawaii
Ocean Time-Series (HOT) Program’s Station ALOHA (22°45’N; 158°W). Nitrate
concentrations were determined with OsmoAnalyzers deployed at depths of 120...
Measurements at the Hawaii Ocean Time-series (HOT) Station ALOHA (22 degrees 45'N, 158 degrees W) have revealed a significant, approximately 50% increase in euphotic zone depth-integrated rates of primary production ( PP; mol C fixed m(-2) d(-1)) based on in situ C-14 experiments. The character of the nearly two-decade increasing...
During austral summer 1997, satellite imagery revealed enhanced chlorophyll associated with the Antarctic Polar Front at 170°W. Phytoplankton growth conditions during the early stages of the spring increase were investigated on the Antarctic Environment and Southern Ocean Process Study Survey I cruise using flow cytometry (FCM) and microscopy to characterize...
Algal chlorophyll and carotenoid distributions were measured periodically in the euphotic zone of Sta. ALOHA (22º45′N, 158º00′W) between February 1989 and October 1991 to document the variability in phytoplankton abundance and composition. The annual mean depth-integrated (O-200 db) concentration of Chl a displayed significant interannual variability. Seasonal patterns in Chl...
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...