How the presence of Nitrogen in the water affects cell size of Karenia brevis and how it alters its

by Kathryn Harring

 

Submitted : Spring 2015

Karenia brevis is a dinoflagellate (a type of algae) that can cause red tide. This project is determining the rate of Karenia brevis growth when Nitrogen is sufficient and when Nitrogen is considered a limiting factor. Then the carrying capacity for the size of the cell will be calculated for both conditions. The amount of toxin found per cell will also be determined under both conditions to determine how the presence of nutrients affect toxin concentration.

It was discovered that Karenia brevis has an approximate steady growth rate when Nitrogen is plentiful. It approximately fits the equation y=.2372x-.3604 and the amount of brevetoxin it presents in the cell tends to decrease. However, when Nitrogen begins to act as a limiting factor, while the cell continues to grow, the rate is stunted and instead it approximately fits into the equation y=0.0759x+1.7345.

The amount of brevetoxin present in Nitrogen limiting cells tends to be much higher than its Nitrogen sufficient counterpart with about 4.5 greater. This shows that Karenia brevis acts in accordance with the carbon nutrient balance hypothesis, which states that when nutrients become limiting, primary producers tend to create more secondary metabolite to prevent further predation until nutrients become more prevalent and it can begin to reproduce again.

The rate of cell size growth was calculated and found that when Nitrogen was sufficient it was 0.2372 and when Nitrogen limiting it was 0.0759. The carrying capacity for the volume of a Karenia brevis cell when Nitrogen is prevalent was calculated to 1.653676. However, the carrying capacity for the volume of a cell in Nitrogen limiting conditions is 1.837901

 

---

 

[ Back ]

	Advisors :
	Arcadii Grinshpan, Mathematics and Statistics
	Alina Corcoran, Florida Fish and Wildlife Conservation Commission/Research Institute
	Suggested By :
	Kathryn Harring