Friday, May 9, 2014

Emily Hladky's Internship, Spring 2014 - Part 7

Hello Everyone! Sadly this will be my last blog but I wanted to give you a recap of my semester! As a reminder, I worked on a project with Dr. Patrick Schwing; the goal of the project was to assess the effects of the Deepwater Horizon oil spill on the community structure of benthic foraminifera. Cores were collected from two affected sites (PCB06 and DSH08) and one natural seep site (Seep A). Foraminifera were picked and identified to the species level from 3 depth increments representing two pre-Deepwater Horizon (DWH) event deposits and one post-DWH event deposit. I then used three indices, the Shannon-Weiner, the Fisher’s Alpha, and the Equitability Index to determine species diversity and evenness.

The dominant species found in 6 of the 7 cores were Bulimina aculeata and Uvigerina peregrina. Bulimina Spp. are often found in environments will low oxygen (Miller and Lohmann, 1982) and Uvigerina Spp. are found where there is low oxygen levels and high organic carbon flux (Miller and Lohmann, 1982). At site PCB06 there is an evident decrease in diversity from the pre-post DWH periods for both Dec. 2010 and Feb. 2011. In 2010 there is a noticeable increase of Bulimina spp., and a 8% increase in Uvigerina spp., which suggests an increased flux of organic matter. In the surface sample of Feb. 2011 there were only 4 forams in the entire increment indicating that the impact from the spill was severe; the decreasing Shannon-Weiner index up-core for both dates, suggests it is the more impacted site in this study. For both Dec. 2010 and Feb. 2011, DSH08 had an increasing species diversity up-core but in Sep. 2011, the diversity seems to slightly decrease. The only significant abundance of Brizalina lowmani in this study was found at the DSH08 location; at the surface for Dec. 2010 and throughout all three samples in Sep. 2011, which suggests extreme oxygen depletion (Platon and Sen Gupta, 2013). Both cores, PCB06 and DSH08 show effects from the DWH event; PCB06 with its decreasing diversity of benthic foraminifera up-core and DSH08 with its lack of density and diversity of benthic foraminifera species in the surface sediments. Seep A seems to be less affected; there is an increase in species diversity up-core which may suggest that the community was already “primed” or adapted to oil deposition. I am still in the process of analyzing my results and will have finalized conclusions soon.

My semester has come to an end with Deep-C and in a little over a week I will be graduating from Eckerd College. I am lucky to be able to continue my research over the summer at the University of Southern Florida, College of Marine Science and want to say thank you to those who have taken the time to read my blog and for the wonderful opportunity Deep-C has given me!  

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Emily Hladky - St. Petersburg, FL

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