University of South Florida St. Petersburg Student Research Journal, Vol. 1, Issue 1, article 2 : Preliminary Effects of Light Attenuation on Thalassia Testudinum Sea Grass of Lassing Park, St. Petersburg, Florida

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Student Research Journal (USFSP)

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Publication Date


Date Issued

September 2011

Date Available

September 2011




Responses to gradients of light availability on seagrass Thalassia testudinum in Tampa Bay, offshore of Lassing Park St. Petersburg, Florida were assessed. Leaf blade features including condition, epiphyte density and invertebrate abundance were measured. Photosynthetically active radiation (PAR) was assessed using a MQ- 200 Quantum Meter with sensor levelling plate. This was utilized in order to establish water clarity parameters related to each treatment (Dixon 2010). Shades attenuating 0%, 50%, and 90% sunlight intensities were constructed and placed in a sequential formation in sea grass plots. The study aimed to measure effects of exposure to decreased light availability on seagrass. Data was collected weekly throughout the 4-week duration of the experiment. Increased epiphyte growth, grazer abundance and damage to blade surface were expected. Additionally a retardation or decrease in blade length growth was anticipated. The experimental design utilized in this experiment was effective. No positive correlation could be established based on data collected between the study treatments and leaf blade features. However blade length growth appeared to have been inhibited in all study plots possibly due to increased disturbance levels. Lack of definitive results can most likely be attributed to the brief duration of study time. Similar studies performed on submerged aquatic vegetation consisted of a 4-week acclimation and 5-month study (Boustany 2010). This experiment would likely yield expected results if replicated over a longer study period.




University of South Florida St. Petersburg


Mentored by Dr. Chantale Begin.

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