Doctor of Philosophy (PhD)


Oceanography and Coastal Sciences

Document Type



Estuaries are biologically productive and important habitats for several fisheries. However, human intervention has separated many estuaries from their needed freshwater source and the commonly used solution is to use diversions to regulate the flow. This episodic increase in nutrients into estuaries has sometimes led to the formation of freshwater cyanobacteria HABs (CyanoHABs). The goal of this dissertation was to look at a field research study of phytoplankton bloom dynamics; management implications for cyanobacteria entering estuaries; and an outreach effort in relation to residents knowledge about cyanobacteria and algae. The first study compared the phytoplankton bloom dynamics, specifically CyanoHABs, in Lake Pontchartrain, Louisiana (LA) during a diversion opening year and a non-opening year. While variations in freshwater flow were found to be important to determine which phytoplankton group dominates the system, species diversity within a group likely was regulated by the water source. During the large flow year (21.9 km3) in 2011, chlorophytes and diatoms were the dominant groups. In 2012, with a much lower flow of 0.3 km3, again chlorophytes and diatoms were dominant in the spring, but both years cyanobacteria numbers significantly increased in the late summer. The second study was conducted in a different estuary of LA (Breton Sound) to determine the salt tolerance of toxic cyanobacteria; the ability of oysters to feed on toxic cyanobacteria; and their ability to retain those toxins in their viscera. The study found that the cyanotoxin, microcystin (MC) was present, where the native oysters inhabit (<10 g kg-1). When the oysters were exposed to toxic Anabaena sp. cells, they fed on these cells and retained MCs. This led to a concern for the public health. The last study surveyed fishermen about their knowledge of algae and HABs. This baseline data was used to create an educational brochure which was distributed to the marinas around Lake Pontchartrain and Lac Des Allemandes. There was also a follow-up survey to determine the effectiveness of the educational brochure. Many of the people surveyed had a basic understanding of algae, but 60% were not familiar with harmful algal blooms.



Document Availability at the Time of Submission

Student has submitted appropriate documentation to restrict access to LSU for 365 days after which the document will be released for worldwide access.

Committee Chair

Bargu, Sibel