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Grantee Research Project Results

Grantee Research Project Results

Chemical Signaling in the Plankton: Multiple Factors Contribute to the Success of the Nuisance Bloom-Forming Alga, Phaeocystis

EPA Grant Number: U915995
Title: Chemical Signaling in the Plankton: Multiple Factors Contribute to the Success of the Nuisance Bloom-Forming Alga, Phaeocystis
Investigators: Long, Jeremy D.
Institution: Georgia Institute of Technology
EPA Project Officer: Boddie, Georgette
Project Period: January 1, 2001 through January 1, 2004
Project Amount: $102,000
RFA: STAR Graduate Fellowships (2001)
Research Category: Academic Fellowships , Aquatic Ecosystems , Fellowship - Aquatic Ecology and Ecosystems



The objective of this research project is to provide empirical support for four factors that contribute to the success of Phaeocystis.


The factors contributing to massive blooms of marine phytoplankton, such as nuisance and harmful algae, remain elusive and largely hypothetical. The cosmopolitan alga, Phaeocystis, forms dense blooms that cause negative economic and ecological effects; yet our understanding of how Phaeocystis forms such blooms remains limited despite previous efforts. This study is investigating the following four factors that contribute to the success of Phaeocystis:

1. Phaeocystis can "smell" the threat of grazing and respond accordingly. When exposed to mixed species of mesozooplankton, the copepod Acartia tonsa, or only chemical signals from these grazers, the alga grew primarily as solitary cells, with colony formation and the proportion of total cells within colonies both being suppressed significantly.

2. Phaeocystis inhibits competitor growth. Chemicals from a bloom of Phaeocystis decreased or inhibited growth of the phytoplankter, Rhodomonas.

3. Phaeocystis blooms are associated with negative impacts on grazer species. Copepod egg hatching success decreased during a Phaeocystis bloom.

4. Phaeocystis is grazed during a small portion of its life cycle. Feeding rates were much greater on senescent colonies than any other stage. In each of these four factors, chemical signals are shown, or suspected, to cause these trophic interactions.

A better understanding of the controls on Phaeocystis blooms should improve our models and the predictions they generate, and may help minimize the nuisance features associated with algal blooms.

Supplemental Keywords:

fellowship, plankton, chemical signaling, Phaeocystis, harmful algal blooms, marine phytoplankton., RFA, Scientific Discipline, Water, Ecosystem Protection/Environmental Exposure & Risk, algal blooms, Atmospheric Sciences, Ecology and Ecosystems, marine ecosystem, bloom dynamics, chemical signaling, Phaeocystis, causative organisms, phytoplankton

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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