Water bottle samples were collected from selected depths (variable with station) at 44 stations in the study area. Coulter counts in the 14 to 28 um size class were routinely determined for comparison with the microscope counts provided by other researchers on the cruise. At six stations, water samples were filtered through a 40 um Nytex mesh and centrifuged for 10 minutes at 1200 x g and then frozen to isolate Karenia brevis cells for subsequent analysis (pg cell-1) of cellular lipid, free amino acid, and protein. The biochemical determinations were performed within two weeks of collection at Kamykowski's laboratory at NCSU.

Belt transects along 3 consecutively-placed, 25m transect lines were surveyed as part of Rapid Ecological Assessments conducted at 12 sites at Johnston Island in January, 2004 NOAA vessel Oscar Elton Sette (OES0401). Raw survey data included species level abundanc estimates.

Belt transects along 3 consecutively-placed, 25m transect lines were surveyed as part of Rapid Ecological Assessments conducted at 9 sites at Lisianski in October, 2004 from the NOAA vessel Hi'ialakai (HI04-01). Raw survey data included species level abundance estimates.

Belt transects along 3 consecutively-placed, 25m transect lines were surveyed as part of Rapid Ecological Assessments conducted at 9 sites at Ofu and Olosega Islands in American Samoa in February, 2004 from the NOAA vessel Oscar Elton Sette (OES04-02). Raw survey data included species level abundance estimates.

Interactions between bacteria and species of harmful and/or toxic algae are potentially important factors affecting both the population dynamics and toxicity of these algae. Recent reports of bacteria lethal to certain harmful algal bloom (HAB) species, coupled with a rapidly evolving interest in attempting to minimize the adverse effects of HABs through various prevention, control, and mitigation strategies, has focused attention on defining the role of algicidal bacteria in bloom termination. The aim of the present study was to determine if algicidal bacteria active against Karenia brevis, a dinoflagellate responsible for frequent and protracted red tides in the Gulf of Mexico, are present in the waters of the west Florida shelf. To date we have detected one algicidal bacterium from samples obtained during ECOHAB-Florida cruises and we are continuing this effort. A taxon-specific 16S rRNA probe was developed for a previously isolated algicidal strain, 41-DBG2, and we have begun to screen water samples for its presence using fluorescent in-situ hybridization. In addition, we have employed denaturing gradient gel electrophoresis (DGGE) to characterize the diversity of the ambient microbial assemblages and to visualize the band characteristic of strain 41-DBG2. This band can then be analyzed further by excising and sequencing. Our screening results to date have yielded negative results on all but one of the field samples tested, which was positive with the rRNA probe. These largely negative findings may not be unexpected due to the marked temporal and spatial separation of the original algicidal bacterial isolation and the water samples being screened. Future efforts will focus on isolating algicidal bacteria from the same bloom event as the samples for screening are obtained, thereby increasing the likelihood of detecting algicidal strains and permitting a more effective analysis of their population dynamics.

Belt transects along 3 consecutively-placed, 25m transect lines were surveyed as part of Rapid Ecological Assessments conducted at 9 sites at French Frigate Shoals in September, 2004 from the NOAA vessel Hi'ialakai (HI04-01). Raw survey data included species level abundance estimates.

Belt transects along 3 consecutively-placed, 25m transect lines were surveyed as part of Rapid Ecological Assessments conducted at 9 sites at Ta'u Islands in American Samoa in February, 2004 from the NOAA vessel Oscar Elton Sette (OES04-02).Raw survey data included species level abundance estimates.

Harmful algal blooms of the toxic dinoflagellate, Karenia brevis, have caused massive fish kills in the Gulf of Mexico since the 1500's, with most occurrences on the west coast of Florida. In 1996, the list of states that have experiences natural resource, public health and economic impacts related to this organism expanded, with the addition of Alabama, Mississippi, and Louisiana, to include all the Gulf-coast states and North Carolina. Estimates of economic impacts to Florida and North Carolina from two moderate intensity blooms ranged from 15 to 25 million dollars respectively. The harmful impacts caused by Karenia brevis occur only when cell concentrations increase significantly above low background concentrations that are present year-round in the Eastern Gulf of Mexico. Once a bloom has developed offshore in typically oligotrophic waters, cell concentrations at the 105 level can be maintained for months. During 21 of the past 22 years, red tide blooms have been observed within the region between Tampa Bay and Charlotte Harbor. The key to understanding any HAB lies in knowing how one algal species has adapted and come to dominate in its particular realm of physical, biological and chemical conditions. Our ability to predict initiation, maintenance, and dispersal of blooms on the Florida shelf has been severely limited by the lack of a quantitative description, or model, of their population dynamics and the physical, biological and chemical regime in which they are embedded. The modeling components of this project will incorporate the quantitative description of blooms and their surrounding environment provided by the field and laboratory portions of this project. The field component will employ a set of monthly hydrographic cruises.