Chlorophyll a is a standard measure for phytoplankton biomass. Routinely, samples for extracted chlorophyll a values are filtered at sea, stored in liquid nitrogen, transported on dry ice and kept at -80 degrees Celsius until extracted. These values are used to examine the relationship between Karenia brevis cell counts, water column toxin levels and chlorophyll a pigment content.

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.

Water bottle samples were collected from selected depths (variable with station) at 14 stations in the study area. Coulter counts in the 14-28 um size class were routinely determined for comparison with the microscope counts. Water samples were filtered through 40 um Nytex mesh and centrifuged for 10 minutes at 1200 x g to isolate Karenia brevis. Pellets were frozen for subsequent analysis (pg cell-1) of total lipid, neutral lipid, free amino acids, protein and RNA. The biochemical determinations were performed within two weeks of collection at Kamykowski's NCSU laboratory. Aliquots were passed through 0.4 um filters; the filters were placed in 90% acetone for subsequent analysis of chlorophyll and the supernatant was analyzed for nitrate.

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 K. 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 annual process cruises.

Water and sediment samples were collected on annual ECOHAB Process cruises and on isolated Mote transects (10/13/99 and 10/20/99). Samples will be analyzed for brevetoxin using a competetive ELISA assay (Naar and Baden, in progress) as well as a receptor-binding assay (VanDolah et al., 1994), and have been analyzed for chlorophyll a (water only) using the Welschmeyer (1994) non-acidification technique.

Data showing chlorophyll a concentrations in Albatross Bay, Gulf of Carpentaria. Phytoplankton pigment composition (chlorophyll a concentration) was measured in Albatross Bay, Gulf of Carpentaria, northern Australia. Four sites were sampled over six years between August 1986 and April 1992. In the last two years samples were taken at the bottom of the water column in addition to mid-depth. This data has been produced by CSIRO for the National Oceans Office, as part of an ongoing commitment to natural resource planning and management through the 'National Marine Bioregionalisation' project.