Physiological and behavioral diagnostics of nitrogen limitation for the toxic dinoflagellate Alexandrium fundyense
type: CreativeWork
description: One challenge in phytoplankton ecology is to measure species-specific physiological responses to changes in environmental conditions. Of particular importance in this regard are harmful algal bloom (RAB) species such as the toxic dinoflagellate Alexandrium fundyense which typically inhabit coastal regions where they are not usually dominant. Within the Gulf of Maine, environmental factors, specifically nitrogen, are likely to be a controlling factor for A. fundyense blooms. Therefore, the ability to ascertain the nutritional status of this species in field assemblages in critical to understanding its bloom dynamics. The aim of this thesis was to identify physiological and behavioral indicators or diagnostics of A. fundyense from the Gulf of Maine, and to evaluate these on natural populations in the Casco Bay region. Using a species-specific monoclonal antibody, two methods for identifying and separating A. fundyense from natural field assemblages were developed. The first used a species-specific antibody and flow cytometry to successfully detect and separate A. fundyense from co-occurring organisms, including other dinoflagellates of equivalent size. In particular the fluorescence associated with the antibody labeling was not sufficient of itself for species discrimination - natural red chlorophyll autofluorescence was also needed as a second parameter for identifying and sorting A. fundyense. A second antibody method was then investigated using immunomagnetic beads to successfully separate live A. fundyense from spiked field samples. The separated cells were then used to obtain accurate chlorophyll, protein and biomass estimates. CHN values were only accurate if the unbound magnetic beads were sieved from the sample prior to analysis. This is probably needed for carbohydrate analysis as well. Since A. fundyense usually inhabits coastal areas that are frequently limited by nitrogen, behavioral adaptations and intracellular responses to nitrogen availability are a pr…
abstract: One challenge in phytoplankton ecology is to measure species-specific physiological responses to changes in environmental conditions. Of particular importance in this regard are harmful algal bloom (RAB) species such as the toxic dinoflagellate Alexandrium fundyense which typically inhabit coastal regions where they are not usually dominant. Within the Gulf of Maine, environmental factors, specifically nitrogen, are likely to be a controlling factor for A. fundyense blooms. Therefore, the ability to ascertain the nutritional status of this species in field assemblages in critical to understanding its bloom dynamics. The aim of this thesis was to identify physiological and behavioral indicators or diagnostics of A. fundyense from the Gulf of Maine, and to evaluate these on natural populations in the Casco Bay region. Using a species-specific monoclonal antibody, two methods for identifying and separating A. fundyense from natural field assemblages were developed. The first used a species-specific antibody and flow cytometry to successfully detect and separate A. fundyense from co-occurring organisms, including other dinoflagellates of equivalent size. In particular the fluorescence associated with the antibody labeling was not sufficient of itself for species discrimination - natural red chlorophyll autofluorescence was also needed as a second parameter for identifying and sorting A. fundyense. A second antibody method was then investigated using immunomagnetic beads to successfully separate live A. fundyense from spiked field samples. The separated cells were then used to obtain accurate chlorophyll, protein and biomass estimates. CHN values were only accurate if the unbound magnetic beads were sieved from the sample prior to analysis. This is probably needed for carbohydrate analysis as well. Since A. fundyense usually inhabits coastal areas that are frequently limited by nitrogen, behavioral adaptations and intracellular responses to nitrogen availability are a pr…
author: Poulton, Nicole J.
language: en_US
keywords: Gonyaulacaceae, Nitrogen
date published: 2000-09
date modified: 2026-07-27T22:05:04Z
provider: Woods Hole Oceanographic Institute
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Massachusetts Institute of Technology and Woods Hole Oceanographic Institution

PropertyValue
property ID: Handle
value: https://hdl.handle.net/1912/3519

PropertyValue
property ID: DOI
value: 10.1575/1912/3519