Relationship of plankton and marine snow to hydrography and currents on the south portion of Georges Bank during June 1997

A key question in biological oceanography is how plankton populations maintain themselves in regions of favorable growth and survival in the face of horizontal transport by ocean currents. Plankton are thought to be retained on the highly productive Georges Bank by the clockwise flow, which intensifies with vernal warming. The extent to which plankton are transported off the bank to the southwest or transported northward and retained on the bank remains poorly understood. This thesis examined the relationship between plankton and physical properties in the southwest corner of the bank, the retention-loss region (RLR). Analysis of field data (Video Plankton Recorder, Acoustic Doppler Current Profiler, and satellite-tracked drifters) and modeling results was performed to quantify the relationships between plankton, hydrography, and currents and the fluxes through the RLR. Temperature-salinity-plankton diagrams and factor analysis revealed that most plankton taxa had characteristic relationships to the hydrography, with the exception of copepods which were everywhere abundant. The flux of plankton during a complete tidal cycle and in the de-tided current data indicated this region was not retentive to plankton, since the bulk of the flow remained to the southwest, despite the presence of a vernally warmed surface layer. A Lagrangian particle trajectory model was used to further examine transport of plankton through the RLR during late spring /early summer (June) when vernal stratification was established. Passive particles were used, since no diel vertical migration by plankton was found in the data. The model revealed that the bulk of the plankton was carried out of the RLR through the southern and western boundaries.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Biology.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Du, Qingling

Advisor dc:contributor.advisor

• Cabell Davis.

• Biology.

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/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/31192

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/31192