Monday, 5 June 2017

Week 3: Florida Gulf Coast University

On Monday our adventure began at the Vester Marine Lab. We visited five different oyster bed sites within Estero Bay to analyze the different organisms living on the oysters. One week prior to our visit Dr. Douglass set down lift nets full of shell fragments at the oyster bed sites we were planning to visit. Then we lifted up the nets to see what we could find. We looked through all the shell fragments and placed and any organisms we found into a bucket. We found and sorted through three lift nets at each site. Then back at the lab we dumped all the buckets out into trays to count and identify each organism that we found. After every bucket had been organized and identified we used the data we collected to create a diversity index in order to compare our findings at each site.  

On Tuesday Dr. Savarese and a couple of his graduate students took us out to an oyster bed near Mound Key to take a core sample. To take a core sample from the ground we used a metal pole that we cut into a 4 meter long section. Then we attached to an apparatus with two smaller metal rods on each side to use as handles and slowly shoved the pole into the oyster bed. We did this until the pole was almost completely in the ground, taking turns pushing it down. Then we had to carefully pull the pole back out of the ground and cap it at both ends. At very tight seal and minimal shifting of the core is essential to preserve the layers of sediment inside. Then we docked at Mound Key and walked around the beautiful park there. Mound Key used to be home to the Calusa Indians that used the shells from oysters they ate to build very large mounds in the middle of the island. The mounds were so large that we could see above the trees all the to the bay from the top of the highest mound. Then once back at the lab the team of graduate students showed use they open the cores using a circular saw to split the core down the middle. Then Dr. Savarese explained what the different layers in the core mean as far as what the land used to be like. He explained that at the very bottom of the core the sediment was probably close to four thousand years old. He also told us that that sediment was dry meaning that four thousand years ago the intertidal oyster beds we were standing on used to be on dry land. 

On Wednesday we were back with Dr. Douglass and he was going to give us a glimpse into what he is currently studying, seagrasses. He took us to six different sites along Estero Bay each known for a different type of seagrass. At each site we took samples of the seagrass using a virnstein device. We also took short core samples of the sediment going down to about two feet, and we did some water quality tests using the YSI meter and a secchi disk. At each site we took three different virnstein sample and two core samples then back at the lab we dumped out our samples into trays to be analyzed. We sorted and identified each organism using the same method we used on Monday and compiled all the data including the water quality tests together for further analysis. We made another diversity index and made a graphs of all the water quality data. We then used this data to make observations and educated guesses as to why we saw the organisms we did based on the different characteristics of each site. 

On Thursday we focused on the different currents of Estero Bay and how the saltwater from the Gulf mixes with the freshwater from the Imperial River. We began our last day in the field with Dr. Parsons teaching us about different ways to measure currents and why they are important. Our study began when we jumped in canoes and Dr. Parsons gave us each a GPS and a grapefruit. However instead of eating the grapefruit we had to use them as our device to analyze current movement. We used grapefruit because they float just below the surface and are light enough to move with the current. We recorded our location, dropped the grapefruit in the water and followed it for about 10 minutes. We then recorded our ending location and repeated this ten different times at different spots along the bay. Then back at the lab we did some different calculations using our data to determine our precise starting and ending latitude and longitude for each trial. Everyone then plotted their data on one big map of Estero Bay and we used this data to draw our own conclusions about how the currents move throughout the bay. 

1 comment:

  1. Great report, Amanda! I'm impressed at all the scientific details you remembered.