Blooms of the toxic dinoflagellate Alexandrium fundyense in the Gulf of Maine : investigations using physical-biological model

Blooms of the toxic dinoflagellate Alexandrium fundyense are annually recurrent in the western Gulf of Maine (WGOM) and pose a serious economic and public health threat. Transitions between and vital rates within the life stages of A. fundyense are influenced by diverse environmental factors, and these biological dynamics combine with energetic physical motions to yield complex bloom patterns. In this thesis, a biological model of the A. fundyense life cycle developed from laboratory and field data is combined with a circulation model to test hypotheses concerning the factors governing A. fundyense blooms in the springs of 1993 and 1994. There is considerable uncertainty with the biological dynamics, and several biological model structures are tested against the 1993 observations. Maximum likelihood theory is used to evaluate the statistical significance of changes in model/data fit between structures. Biological formulations that do not include either nitrogen limitation or mortality overestimate observed cell abundances and are rejected. However, formulations using a wide range of mortality and nitrogen dependence, including the exclusion of one or the other, were able to match observed bloom timing and magnitude and could not be statistically differentiated. These simulations suggest that cysts germinating offshore of Casco Bay provide a plausible source of cells for the blooms, although cell inputs from the eastern Gulf of Maine gain importance late in the spring and in the northeast portion of the study area. Low net growth rates exert a notable yet non- dominant influence on the modeled bloom magnitude. When simulations tuned to 1993 were applied to 1994 the degree of model/data fit is maintained only for those simulations including nitrogen dependence.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Civil and Environmental Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Stock, Charles A. (Charles Andrew), 1975-

Advisor dc:contributor.advisor

• Dennis J. McGillicuddy.

• Civil and Environmental Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/30192
• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Identifier URI

http://dspace.mit.edu/handle/1721.1/30192

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/30192