Papers by Gary Kirkpatrick
Applied Optics, 2006
We applied two numerical methods to in situ hyperspectral measurements of remote sensing reflecta... more We applied two numerical methods to in situ hyperspectral measurements of remote sensing reflectance R rs to assess the feasibility of remote detection and monitoring of the toxic dinoflagellate, Karenia brevis, which has been shown to exhibit unique absorption properties. First, an existing quasi-analytical algorithm was used to invert remote sensing reflectance spectra, R rs ͑͒, to derive phytoplankton absorption spectra, a Rrs ͑͒. Second, the fourth derivatives of the a Rrs ͑͒ spectra were compared to the fourth derivative of a reference K. brevis absorption spectrum by means of a similarity index (SI) analysis. Comparison of reflectance-derived a with filter pad measured a found them to agree well ͑R 2 ϭ 0.891; average percentage difference, 22.8%). A strong correlation ͑R 2 ϭ 0.743͒ between surface cell concentration and the SI was observed, showing the potential utility of SI magnitude as an indicator of bloom strength. A sensitivity analysis conducted to investigate the effects of varying levels of cell concentrations and colored dissolved organic matter (CDOM) on the efficacy of the quasi-analytical algorithm and SI found that a Rrs ͑͒ could not be derived for very low cell concentrations and that, although it is possible to derive a Rrs ͑͒ in the presence of high CDOM concentrations, CDOM levels influence the a Rrs ͑͒ amplitude and shape. Results suggest that detection and mapping of K. brevis blooms based on hyperspectral measurements of R rs are feasible.
Environmental Health Perspectives, 2009
Limnology and Oceanography, 1988
The movement of a representative photosynthetic marine dinoflagellate, Gyrodinium dorsum, was vid... more The movement of a representative photosynthetic marine dinoflagellate, Gyrodinium dorsum, was videotaped on a temperature-gradient plate, in a single-chambered, water-jacketed cuvette and in a six-chambered, light-gradient, water-jacketed cuvette. The tapes were analyzed with intercalibrated manual or computer-assisted techniques. The swimming ability of G. dorsum varied in response to changes in temperature, light intensity, and buoyancy. A FORTRAN computer model combined mathematical formulations describing these empirical responses and some assumed covariation to predict the instantaneous translational velocity of G. dorsum. After the model was verified with an independent data set collected from the single-chambered, water-jacketed cuvette, it was used to simulate imposed diel vertical migrations in thermally stratified coastal water. The translational velocity of G. dorsum varied about 3-fold in response to the imposed environmental variation. This modulation of the translational velocity of a photosynthetic marine dinoflagellate can combine with variability of the physical motion spectrum to affect the temporal and spatial occurrence of the organism and the suitability of its growth conditions.
Marine Biology, 1992
Six marine dinoflagellate species representing a range of equivalent spherical diameters between ... more Six marine dinoflagellate species representing a range of equivalent spherical diameters between 12 and 36 μm were examined for several characteristics that influence their translation velocity. Sinking velocities estimated by three independent techniques and applied to swimming and narcotized cells generally agreed, and followed the cell-size relationships previously reported for diatoms. Dinokont sinking and swimming velocities both decreased with increasing surface area: volume ratio, but a small desmokont deviated from the dinokont relationships. Sinking velocities influenced the relative ascent/descent capabilities of a species. The swim:sink ratio decreased as equivalent spherical diameter increased to 25 μm and then remained constant at 7.6, despite further increases in cell size. This relationship suggests a minimum required swimming capability relative to cell size. The swim:sink ratio increased with increasing surface area:volume ratio for all the surveyed species. Out observations of decreasing cell rotation:translation ratio and increasing cell drag with increasing cell size supported the hypothesis that the dinoflagellate flagellar apparatus generates maximum swimming velocity at intermediate cell sizes. However, an alternate analysis supported the hypothesis that swimming velocity increases with cell size and that variations among genera are due to subtle differences in the basic dinoflagellate propulsion system. A three-dimensional helical path index provided a more realistic estimate of the actual translation velocity (along the helix axis) during diel vertical migration when applied as a correction factor to the more typically measured helix velocity (along the helix) of a given dinoflagellate.
Continental Shelf Research, 2008
As a component of the ECOHAB Florida Regional Field Program, this study addresses cell cycle beha... more As a component of the ECOHAB Florida Regional Field Program, this study addresses cell cycle behavior and its importance to bloom formation of the Florida red tide dinoflagellate, Karenia brevis. The cell cycle of K. brevis was first studied by flow cytometry in laboratory batch cultures, and a laboratory mesocosm column, followed by field populations over the 5-year course of the ECOHAB program. Under all conditions studied, K. brevis displayed diel phased cell division with S-phase beginning a minimum of 6 h after the onset of light and continuing for 12-14 h. Mitosis occurred during the dark, and was generally completed by the start of the next day. The timing of cell cycle phases relative to the diel cycle did not differ substantially in bloom populations displaying radically different growth rates (m min 0.17-0.55) under different day lengths and temperature conditions. The rhythm of cell cycle progression is independent from the rhythm controlling vertical migration, as similar cell cycle distributions are found at all depths of the water column in field samples. The implications of these findings are discussed in light of our current understanding of the dinoflagellate cell cycle and the development of improved models for K. brevis bloom growth. Published by Elsevier Ltd.
Harmful Algae, 2013
Autonomous underwater gliders with customized sensors were deployed in October 2011 on the centra... more Autonomous underwater gliders with customized sensors were deployed in October 2011 on the central West Florida Shelf to measure a Karenia brevis bloom, which was captured in satellite imagery since late September 2011. Combined with in situ taxonomy data, satellite measurements, and numerical circulation models, the glider measurements provided information on the three-dimensional structure of the bloom. Temperature, salinity, fluorescence of colored dissolved organic matter (CDOM) and chlorophyll-a, particulate backscattering coefficient, and K. brevis-specific chlorophyll-a concentrations were measured by the gliders over >250 km from the surface to about 30-m water depth on the shallow shelf. At the time of sampling the bloom was characterized by uniform vertical structures, with relatively high chlorophyll-a and CDOM fluorescence, low temperature, and high salinity. Satellite data extracted along the glider tracks demonstrated coherent spatial variations as observed by the gliders. Further, the synoptic satellite observations revealed the bloom evolution during the 7 months between late September 2011 and mid April 2012, and showed the maximum bloom size of $3000 km 2 around 23 November. The combined satellite and in situ data also confirmed that the ratio of satellite-derived fluorescence line height (FLH) to particulate backscattering coefficient at 547 nm (b bp (547)) could be used as a better index than FLH alone to detect K. brevis blooms. Numerical circulation models further suggested that the bloom could have been initiated offshore and advected onshore via the bottom Ekman layer. The case study here demonstrates the unique value of an integrated coastal ocean observing system in studying harmful algal blooms (HABs). ß
Oceans, 2012
The U.S. Integrated Ocean Observing System is being designed to be an end-to end, integrated, sus... more The U.S. Integrated Ocean Observing System is being designed to be an end-to end, integrated, sustained, operational System of Systems that provides data, information and products to benefit a broad range of stakeholders in their decision-making. These design concepts form the basis of pilot projects being undertaken by the Gulf of Mexico Coastal Ocean Observing System Regional Association (GCOOS-RA). This paper presents a case study of the GCOOS-RA Harmful Algal Bloom Integrated Observing System (HABIOS) Project. A set of research activities related to harmful algal blooms is examined for eventual transition from pilot project to an integrated operational system. The end-to-end nature of the system is explored from the perspectives of design and operation, data management and communication, modeling and analysis, decision-support tools and outreach, and benefits to stakeholders at national, regional, state, and local levels. The case study of the HABs pilot projects will demonstrate that HAB-related observations need to be both sustained and operational, and that progress is being may through the integration of the efforts of many entities concerned with detecting and monitoring HAB events and mitigating HAB impacts.
Harmful Algae, 2013
Autonomous underwater gliders with customized sensors were deployed in October 2011 on the centra... more Autonomous underwater gliders with customized sensors were deployed in October 2011 on the central West Florida Shelf to measure a Karenia brevis bloom, which was captured in satellite imagery since late September 2011. Combined with in situ taxonomy data, satellite measurements, and numerical circulation models, the glider measurements provided information on the three-dimensional structure of the bloom. Temperature, salinity, fluorescence of colored dissolved organic matter (CDOM) and chlorophyll-a, particulate backscattering coefficient, and K. brevis-specific chlorophyll-a concentrations were measured by the gliders over >250 km from the surface to about 30-m water depth on the shallow shelf. At the time of sampling the bloom was characterized by uniform vertical structures, with relatively high chlorophyll-a and CDOM fluorescence, low temperature, and high salinity. Satellite data extracted along the glider tracks demonstrated coherent spatial variations as observed by the gliders. Further, the synoptic satellite observations revealed the bloom evolution during the 7 months between late September 2011 and mid April 2012, and showed the maximum bloom size of $3000 km 2 around 23 November. The combined satellite and in situ data also confirmed that the ratio of satellite-derived fluorescence line height (FLH) to particulate backscattering coefficient at 547 nm (b bp (547)) could be used as a better index than FLH alone to detect K. brevis blooms. Numerical circulation models further suggested that the bloom could have been initiated offshore and advected onshore via the bottom Ekman layer. The case study here demonstrates the unique value of an integrated coastal ocean observing system in studying harmful algal blooms (HABs). ß
Marine Ecology Progress Series, 2013
Harmful Algae, 2014
ABSTRACT The diel change in dissolved oxygen concentrations were recorded with an automated incub... more ABSTRACT The diel change in dissolved oxygen concentrations were recorded with an automated incubator containing a pulsed oxygen sensor in Sarasota Bay, Florida. The deployments occurred during a ‘pre-bloom’ period in May to June 2006, and during a harmful algal bloom dominated by Karenia brevis in September 2006. The diurnal (daylight) increase in dissolved oxygen concentrations varied from 16 to 104 μmol O2 l−1 with the corresponding nocturnal decrease in oxygen varying from 16 to 77 μmol O2 l−1. Nocturnal respiration consumed 42–113% of the diurnal net oxygen production with the minimum and maximum during the pre-bloom period. Hourly production rates closely followed fluctuations in irradiance with maximum rates in the late morning. Hourly oxygen utilization rates (community respiration) at night were highest during the first few hours after sunset.
Florida journal of environmental health, 2009
Harmful algae, 2010
Florida red tides, an annual event off the west coast of Florida, are caused by the toxic dinofla... more Florida red tides, an annual event off the west coast of Florida, are caused by the toxic dinoflagellate, Karenia brevis. K. brevis produces a suite of potent neurotoxins, brevetoxins, which kill fish, sea birds, and marine mammals, as well as sickening humans who consume contaminated shellfish. These toxins become part of the marine aerosol, and can also be inhaled by humans and other animals. Recent studies have demonstrated a significant increase in symptoms and decrease lung function in asthmatics after only one hour of beach exposure during an onshore Florida red tide bloom.This study constructed a transect line placing high volume air samplers to measure brevetoxins at sites beginning at the beach, moving approximately 6.4 km inland. One non-exposure and 2 exposure studies, each of 5 days duration, were conducted. No toxins were measured in the air during the non-exposure period. During the 2 exposure periods, the amount of brevetoxins varied considerably by site and by date. ...
Science of The Total Environment, 2014
To mitigate the damages of natural hazards, policy responses can be beneficial only if they are e... more To mitigate the damages of natural hazards, policy responses can be beneficial only if they are effective. Using a self-administered survey approach, this paper focuses on the adherence to local fertilizer ordinances (i.e., county or municipal rules regulating the application of fertilizer to private lawns or facilities such as golf courses) implemented in jurisdictions along the Southwest Florida coast in response to hazardous blooms of Florida red tides (Karenia brevis). These ordinances play a role in the context of evolving programs of water pollution control at federal, state, water basin, and local levels. With respect to policy effectiveness, while the strength of physical linkages is of critical importance, the extent to which humans affected are aware of and adhere to the relevant rules, is equally critical. We sought to understand the public's depth of understanding about the rationales for local fertilizer ordinances. Respondents in Sarasota, Florida, were asked about their fertilizer practices in an area that has experienced several major blooms of Florida red tides over the past two decades. A highly educated, older population of 305 residents and "snowbirds" reported relatively little knowledge about a local fertilizer ordinance, its purpose, or whether it would change the frequency, size, or duration of red tides. This finding held true even among subpopulations that were expected to have more interest in or to be more knowledgeable about harmful algal blooms. In the face of uncertain science and environmental outcomes, and with individual motivations at odds with evolving public policies, the effectiveness of local community efforts to decrease the impacts of red tides may be compromised. Targeted social-science research on human perceptions about the risks of Florida red tides and education about the rationales for potential policy responses are warranted.
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Papers by Gary Kirkpatrick