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Publication Date

2010-01-01

Availability

UM campus only

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Marine Biology and Fisheries (Marine)

Date of Defense

2010-07-13

First Committee Member

Larry E. Brand - Committee Chair

Second Committee Member

Jeffrey S. Prince - Committee Member

Third Committee Member

Patricia L Blackwelder - Outside Committee Member

Abstract

Harmful algal blooms (HABs) along the Florida coast have been reported for many decades. Karenia brevis is a red tide species on the West Florida Shelf, producing a suite of toxins called brevetoxins that adversely affect marine organisms and humans. Dinoflagellate cysts have been studied as a tool for red tide studies since the location where cysts accumulate in the sediments and the size of the seed beds can be important for potential blooms. However, little attention has been paid on the dinoflagellate cysts on the West Florida Coast. This study describes the distribution of dinoflagellate cysts along the West Florida Coast and proposes the possibility of Karenia brevis cysts. Samples were collected with a box corer July 17-29 and October 5-17, 2009. Overall cyst concentrations are low. The sediments along the West Florida Coast compose of coarse-sized grains that generate large-sized pores. Thus, cysts in the coarse-grained sediments might easily move along with turbulence or water movements flowing above the sediments. Cyst concentrations gradually increased shoreward. The hydrographic features along the West Florida Coast are influenced by the coastal current. Southward coastal current flowed during two cruises might drive a subsequent offshore Ekman transport which might lead to a coastal upwelling, thereby transporting bottom sediments closer to the coast. Thus, cyst concentration was higher inshore compared to that offshore. The average concentration of heterotrophic dinoflagellate cysts was higher in July than that in October, whereas autotrophic dinoflagellate cysts did not have a noticeable difference between July and October. The heterotrophic group is dominated by a protoperidinioid group that mainly feeds on diatoms. The abundance of protoperidinioid was higher in July than in October and other groups have similar abundance between two periods. The highest abundance of diatoms is in June, July and August, whereas the lowest was in October, November and May. Therefore, the decrease in the abundance of protoperidinioid cysts correlates with the lower food supply for their motile cells. Based on a morphological similarity to a Karenia brevis cyst detected in culture by Walker (1982) and a morphological difference from other species belonging to the same genus, cysts that are probably Karenia brevis have been identified.

Keywords

Dinoflagellate Cysts; West Florida Coast; HABs

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