Grantee Research Project Results

Final Report: ECOHAB - Hydrography and Biology to Provide Information for the Construction of a Model to Predict the Initiation, Maintanence and Dispersal of Red Tide on the West Coast of Florida

EPA Grant Number: R829456
Title: ECOHAB - Hydrography and Biology to Provide Information for the Construction of a Model to Predict the Initiation, Maintanence and Dispersal of Red Tide on the West Coast of Florida
Investigators: Steidinger, Karen A. , Kirkpatrick, Gary J. , Schofield, Oscar M.E. , Kamykowski, Daniel , Redalje, Donald , McGuire, Peter , Lohrenz, Steven
Institution: Florida Fish and Wildlife Conservation Commission , North Carolina State University , University of Southern Mississippi , Rutgers University - New Brunswick , University of South Florida
Current Institution: Florida Fish and Wildlife Conservation Commission , North Carolina State University , Rutgers University - New Brunswick , University of South Florida , University of Southern Mississippi
EPA Project Officer: Packard, Benjamin H
Project Period: December 15, 2001 through September 30, 2003
Project Amount: $450,000
RFA: Ecology and Oceanography of Harmful Algal Blooms (2001) RFA Text |  Recipients Lists
Research Category: Aquatic Ecosystems , Water

Objective:

The objectives of the project were to: (1) create models to predict red tide landfall, (2) identify the physical habitat associated with bloom concentration and transport, (3) elucidate the interactions of biological and environmental factors that lead to bloom development, (4) examine the inorganic and organic nutrient levels and sources, and (5) evaluate the production, occurrence, fate, and effects of brevetoxin in the environment.

Seven of the original 24 investigators were funded during the final year, and several were in their second year of funding as a result of phased funding. The final year of the project was dedicated to investigating Karenia brevis (= Gymnodinium breve) population dynamics and collecting even more synoptic field data to help identify the physical -chemical -biological regime associated with blooms.

Summary/Accomplishments (Outputs/Outcomes):

Experiments to assess the degree of relatedness between different geographic isolates (Mexico Beach, Apalachicola, Piney Island, Sarasota, Charlotte Harbor, Florida Keys, Jacksonville, and Texas) demonstrated there were no differences in sequences between the isolates when examining diversity regions 1 and 2 (D1, D2). This suggests that there are no large subunit rDNA polymorphisms among the sequenced isolates, but subsequent tests were performed using TA cloning to verify this result. Comparison of all the isolates sequences (except for Jacksonville and Florida Keys, which had ongoing technical problems) indicated near identity with the GenBank accession AF172714. This confirms that they are internally consistent with no small subunit sequence diversity among the 15 isolates and no polymorphisms exist either.

Spectral signatures to discriminate phytoplankton taxa in vivo to detect red tides using remote sensing were investigated. The phytoplankton and chromophoric dissolved organic matter (CDOM) loads for Charlotte Harbor were identifiable with this method and can be used effectively to define the difference between terrestrial and oceanic CDOM. The optical phytoplankton inversion (IOP inverter) for three phytoplankton spectral classes were tested against high performance liquid chromatography/ChemTax estimates of total chlorophyll associated with the major bloom-forming taxa. The results show this method accurately (p < 0.05) predicts the concentration of phytoplankton containing chlorophyll c and phycobilin but not chlorophyll b (chlorophytes). These results demonstrate that the IOP inverter provides reasonable estimates of phytoplankton biomass, and the Ac-9 instrument can reasonably estimate the spectral absorption of CDOM particles, detritus, and phytoplankton. Research was conducted during two Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) Process cruises in October of 2000 and 2001. During the first cruise a pulse amplitude modulation (PAM) fluorometer was used to measure the maximum quantum yield of Photosystem II, and a tethered spectral radiometer Satlantic buoy was used to measure the hyperspectral reflectance in a natural K. brevis population. Using the PAM fluorometer, diurnal quenching was found in these natural populations—because of xanthophyll cycling. Using populations incubated on deck at 150 and 300 μmol photons m^-2 s^-1 light, the amount of Microsporine-like amino acids (MAAs) produced was measured. No MAA s were produced at the lower light levels, but significant MAA s were produced in the higher light levels implying K. brevis is well acclimated to living in high ultraviolet surface waters. Using an Ac-9 in a bloom tracked with lagrangian drifters in October 2001, light absorption and attenuation parameters dramatically increased ( five fold) in surface waters diurnal as K. brevis populations vertically migrated into surface waters. Highest values for light absorption and attenuation were found around 16:00 hours local standard time. Vertical migration of K. brevis disproportionately increased the R_rs remote signal in moderate resolution imaging spectroradiometer and SeaWifs imagery. It altered the magnitude and spectral shape of R_rs depending upon the spectrum of light, increasing in the red (backscatter) and decreasing in the blue and green wavelengths. This alteration in R_rs may contribute to why a K. brevis bloom can appear red to an observer.

To identify the physical habitat associated with bloom concentration and transport, elucidate the interactions of biological and environmental factors that lead to bloom development, and examine the inorganic and organic nutrient levels and sources, monthly synoptic cruises aboard the RV Bellows and Suncoaster were continued collecting vertical profiles of conductivity, temperature, density, and chlorophyll fluorescence at each of the greater than 70 stations. Various nutrient, live and preserved cell counts, and extracted chlorophyll measurements were made at every other station. Continuous measurements of surface temperature, salinity, turbidity, particle scattering, and fluorescence were made throughout the cruise via a flow through on deck system. The most recent Florida Red Tide Historical Database (through 2002) is available.

Small boat cruises along the Sarasota transect to the 50 km offshore within the ECOHAB control volume were continued. Every 8 km, water column data were collected including salinity, temperature, fluorescence, turbidity, and photosynthetic active radiation (PAR) profiles. Discrete measurements of water clarity, chlorophyll a, inorganic N and P, dissolved silica, and K. brevis counts were taken at certain depths. Continuous flow-through measurement of surface temperature, salinity, fluorescence, and PAR were made between stations. During the yearly ECOHAB:Process cruises (October 2001 and September 2002), deployment of the self-contained underwater photosynthesis apparatus (SUPA) was a priority. SUPA measures diurnal patterns of photosynthetic quantum yield and photoacclimation in surface and subsurface populations. Along the Sarasota ECOHAB:Florida transect diatoms contribute the most phytoplankton biomass. Cyanophytes also contribute greatly to offshore samples, but during red tides dinoflagellates dominate biomass. In the absence of a K. brevis bloom, chlorophyll reached up to 10 μg L^-1. However, during a red tide chlorophyll values were typically less than 3 μg L^-1 unless more than 100 x 10³ cells L^-1 were found.

Bloom initiation has differed throughout the transect area over the years, with conditions ranging from initiation offshore at depth and progression landward to first detection of the bloom onshore. Estuarine discharge varied widely during the comprehensive study period and was not correlated to the initiation of red tides. Ratios of organic nutrients from the sampling area indicate luxury consumption of nitrogen by phytoplankton and ultimately phosphorus limitation. Silica was not consistently related to salinity, indicating that seasonal variability and uptake by diatoms can override typical offshore gradients. Concentration of silica on the bottom was generally higher than at the surface. Trace metal concentrations were elevated nearshore, as associated with terrigenous inputs. Iron was not well correlated with K. brevis blooms during the study period. Manganese concentrations were significantly positively correlated to K. brevis concentration, but many outliers were present and some periods of high manganese concentration were not associated with K. brevis blooms.

A method was developed to quantify the lipid content of previously collected samples of K. brevis stained with Nile Red using an epifluorescent microscope. This method also works with flow cytometry. Specially designed laboratory incubation systems were developed to better characterize the migration ability of K. brevis, specifically focusing on swimming behavior in response to temperature, interclonal consistency in nutrient chemotactic, and photosynthetic responses. Each of eight clonal cultures divided into two groups, one more light capable than the other. This suggests that different clones have different photoresponse capabilities. Interestingly, the Wilson clone represents the low photoresponse but is widely used for physiological studies. Vertical shear may also be an important distinguishing factor in these subpopulations. A small scale biophysical model, previously developed, was modified to accommodate bloom development and transport in three dimensions.

Research on the interactions of cellular, behavioral, live cycle, and community regulation processes with environmental forcing factors during stages of bloom development included studies of pigments that function in photobiological responses of phytoplankton communities using radioactive tracers and conducting in situ and on deck experiments of the photosynthetic, physiological, and growth dynamics using natural light. Vertically integrated primary production (IPP) was both higher in fall 2001 (IPP = 0.92 ± 0.48 g C m^-2 d^-1) and more variable than during fall 2000 (IPP = 0.53 ± 0.07 g C m^-2 d^-1). Cell counts were much greater during fall 2001 (500-800 cells L^-1 versus 100-400 cells L^-1 for fall 2000), contributing to the greater production. Cruise data indicate carbon specific growth rates of 0.1 – 0.3 d^-1. Carbon biomass values ranged from 20-30 percent of the surface particulate organic carbon (POC). Although POC remained fairly constant throughout the water column, phytoplankton carbon decreased steadily at depth. Microalgal POC, derived from radioactive isotope tracers, represent only a small amount of the water column POC. This means the blooms were not dominated by algal POC, which is currently being used to distinguish K. brevis blooms from other blooms using remote sensing. Shallow and deep populations differentially incorporate radiolabelled ¹⁴C into proteins or lipids. Deep samples incorporated ¹⁴C into proteins much more than into lipids as compared to the surface samples. Experiments with nutrient additions and ¹⁴C incorporation were less clear but suggested that the K. brevis populations encountered during the cruises were nitrogen limited. K. brevis blooms dominated the total scattering in light, which held true even for migrating populations, and the ratio of backscattering coefficient to absorption at both 440 and 550 nm may be unique for these blooms.

Conclusions

The specific objectives of the project were met with the exception of examining the biological (lifecycle) interactions that lead to bloom development, although this work continues. The funded investigators made significant progress towards the ability to create models to predict red tide landfall. Cultures were found to be identical in genetic sequence at the level investigated, ruling out potential causes for variable expression of toxin. Other investigations provided more insight into the consequences of vertical migration in K. brevis at both the organism and remote sensing level. Finally, additional synoptic hydrographic and nutrient data from the West Florida Shelf during both bloom and non bloom conditions were collected and disseminated, along with the data collected during Process cruises, to principle investigators.

Supplemental Keywords:

Karenia brevis, Gymnodinium breve, Florida, red tide, initiation, maintenance, transport, coastal waters, harmful algal blooms, ecological effects, population effects, brevetoxins,, RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Geographic Area, Water, algal blooms, Health Risk Assessment, Ecosystem Protection, Ecology, Ecosystem/Assessment/Indicators, Oceanography, Southeast, Ecological Effects - Environmental Exposure & Risk, Gulf of Mexico, Ecology and Ecosystems, ECOHAB, ecological effects, Florida, G. breve red tides, red tides, Gymnodinium breve toxins, ecological models, West Coast of Florida, brevetoxins, ecological exposure, dinoflagellate, dinoflagellate Gymnodinium breve, harmful algal blooms

Progress and Final Reports:

Original Abstract

2002 Progress Report