Browsing Cullen, John by Title
Now showing items 11-30 of 37
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Hypotheses to Explain High-Nutrient Conditions in the Open Sea
Oceanic high-nutrient, low-chlorophyll waters are characterized principally by the persistence of major nutrients at the sea surface. This condition indicates control of autotrophic production by something other than NO3 ... -
Impact of ultraviolet radiation on marine crustacean zooplankton and ichthyoplankton: a synthesis of results from the estuary and Gulf of St. Lawrence, Canada
The objectives of the research program reported upon here were (1) to measure ambient levels of UV radiation and determine which variables most strongly affected its attenuation in the waters of the estuary and Gulf of St. ... -
Inferred influence of nutrient availability on the relationship between Sun-induced chlorophyll fluorescence and incident irradiance in the Bering Sea
This study examines variability in the relationship between Sun-induced chlorophyll fluorescence and incident solar irradiance as a potential diagnostic of the nutritional status of phytoplankton. The study site is the ... -
Inhibition of marine photosynthesis by ultraviolet radiation: Variable sensitivity of phytoplankton in the Weddell-Scotia Confluence during the austral spring
To assess the potential impacts of ozone depletion on photosynthesis in the Southern Ocean, we need to know more about effects of ultraviolet radiation (UV) on phytoplankton in Antarctic waters, where, in addition to ... -
Mapping coastal optical and biogeochemical variability using an autonomous underwater vehicle and a new bio-optical inversion algorithm
Autonomous underwater vehicles (AUVs) can map water conditions at high spatial ( horizontal and vertical) and temporal resolution, including under cloudy conditions when satellite and airborne remote sensing are not feasible. ... -
Methyl iodide in the NW Atlantic; spatial and seasonal variation
While the global ocean is an important source of atmospheric methyl iodide (CH (sub 3) I), the major producers of CH (sub 3) I within the ocean remain unclear. During a seasonal study in the NW Atlantic, the relationship ... -
Modeling the effects of ultraviolet radiation on embryos of Calanus finmarchicus and Atlantic cod (Gadus morhua) in a mixing environment
It is well established that ultraviolet radiation (UVR, 280-400 nm) harms aquatic organisms. Reductions in productivity have been reported for phytoplankton, ichthyoplankton, and zooplankton in incubations exposed to UVR. ... -
New algorithms for MODIS sun-induced chlorophyll fluorescence and a comparison with present data products
We discuss important sources of variability in sun-induced chlorophyll fluorescence and examine difficulties in deriving fluorescence data products from satellite imagery, with a focus on the MODerate-resolution Imaging ... -
New production in the warm waters of the Tropical Pacific Ocean
The average depth-integrated rate of new production in the tropical Pacific Ocean was estimated from a calculation of horizontal and vertical nitrate balance over the region enclosed by the climatological 26 degree C ... -
Ocean Fertilization Science, Policy, and Commerce
Over the past 20 years there has been growing interest in the concept of fertilizing the ocean with iron to abate global warming. This interest was catalyzed by basic scientific experiments showing that iron limits primary ... -
Optical detection and assessment of algal blooms
Concerns about harmful algal blooms (HABs) have grown in recent years. There is a pressing need for robust, quantitative, and cost-effective methods to detect and characterize algal blooms. Critical applications of these ... -
Optical detection and assessment of algal blooms
Concerns about harmful algal blooms (HABs) have grown in recent years. There is a pressing need for robust, quantitative, and cost-effective methods to detect and characterize algal blooms. Critical applications of these ... -
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Photosynthetic characteristics and estimated growth rates indicate grazing is the proximate control of primary production in the Equatorial Pacific
Macronutrients persist in the surface layer of the equatorial Pacific Ocean because the production of phytoplankton is limited. Measurements of photosynthesis as a function of irradiance (P-I) provide information on the ... -
Phytoplankton Growth and Light-Absorption as Regulated by Light, Temperature, and Nutrients
Numerous studies of the growth of phytoplankton in the laboratory have demonstrated the dependence of cellular pigment concentration and growth rate upon light intensity, photoperiod, temperature, and nutrient supply. These ... -
Predicting and verifying the intended and unintended consequences of large-scale ocean iron fertilization
Ocean iron fertilization (OIF) is being considered as a strategy for mitigating rising atmospheric CO2 concentrations. One model for implementation is the sale of carbon offsets. Modeling studies predict that OIF has the ... -
Primary production by suspended and benthic microalgae in a turbid estuary: Time-scales of variability in San Antonio Bay, Texas
The within-day, between-day and month-to-month variability of light attenuation and microalgal chlorophyll a (chl a) and photosynthetic response was measured in San Antonio Bay, Texas, USA. Waters were shallow (<2 m) ... -
Primary Production Estimates from Recordings of Solar Stimulated Fluorescence in the Equatorial Pacific at 150-Degrees-W
Biological, optical, and hydrographical data were collected on the WEC88 cruise along 150-degrees-W and during a 6-day time series station on the equator during February/March 1988. This area was characterized by a subsurface ... -
Relationships between vertical mixing and photoadaptation of phytoplankton: Similarity criteria
In their natural environment phytoplankton are exposed to fluctuations in incident irradiance due to vertical displacements in the water column induced by turbulent fluid motion. A reaction-diffusion model is analyzed to ...