Friday, February 13, 2015

Sea turtles of Abaco, Bahamas

PhD Student Elizabeth Whitman has been working on green turtles of Abaco Bahamas since last summer.   As part of her research she put up large cages (exclosures) that keep turtles from grazing on the seagrass.  By placing exclosures in different areas she hopes to figure out how important turtles are in structuring seagrass beds and whether their importance varies in space and time.  Below is a summary of her brief field trip in November, 2014 to check on her experiment.  Check back later this spring to read about her upcoming work to deploy cameras on turtles on several islands in the Caribbean!


This past November I revisited my study sites on Abaco to collect data and check on the condition of the exclosure cages.
Linda Gardner performing seagrass shoot counts in one of the full exclosure cages.
At each of the exclosure study sites (Bight of Old Robinson creeks, Snake Creek, and Hill’s Creek) we first visited each plot and marked 10 seagrass shoots that we would collect one week later to measure growth. I was pleasantly surprised at the good condition of the exclosures (they have been out for months now), so over the course of our trip we only needed to perform minor repairs and cleaning. We also surveyed the seagrass and algae, measured seagrass canopy height, and counted shoot density within each plot . 
The location of seagrass shoots marked for growth measurements are marked by the white flag; seagrass and algae surveys were conducted within 50 x 50 cm quadrats at four locations within each plot

Visually, the seagrass appears to be benefiting from the protection from grazing at Hill’s Creek, but I am still working on the analyses and it might take more time to see a big effect if there is one. With the help of local volunteers who will be visiting the cages during my absence, this experiment will run through the summer of 2015 when I will be back for my next round of data collection. By keeping the exclosures in place for one full year, the I will get a more accurate picture of green turtle grazing behavior and the effects of green turtle grazing on the seagrass in the creeks of Abaco.
Back at the lab at Florida International University I am busy, along with a few undergraduate volunteers, prepping the seagrass we collected for nutrient analysis. I am also actively working to secure support for my summer research trip and to expand upon the sea turtle field course and tagging program with Friends of the Environment.

An exclsure cage viewed from above the water.

A small nurse shark resting in the seagrass.