Samantha Politano: Analyzing Potential Impact of Deepwater Horizon Oil Spill on Sponge Communities

Samantha Politano is a 2020 Stephen and Ina McNichols grant winner who is majoring in Environmental Science and Policy. Her project is tentatively titled “Sponge communities in mesophotic reefs of the Gulf of Mexico before and after the Deepwater Horizon oil discharge”. Samantha’s faculty mentor is Prof. Ian MacDonald in the Department of Earth, Ocean, and Atmospheric Sciences.

In Fall 2019, I began my Honors in the Major thesis by analyzing photos taken by the
MacDonald lab after the 2010 Deepwater Horizon (DWH) oil spill to quantify pathologies of mesophotic octocorals and anthipatharians that were under the influence of floating oil in the weeks following the DWH incident. I am reviewing these photos under a different context—the possible impacts the spill had on sponges in two mesophotic reefs of the Gulf of Mexico. In each photo, I count the number of sponges and bin them by color. Due to the quality of the images and the nature of sponge biology, it is impossible to identify sponge taxa.

For the photos from 2014, I determined that Roughtongue Reef (the reef further from the site of the oil spill) had a higher average number of sponges per photo at 21.1, compared to Alabama Alps Reef at 3.47. A t-test determined this data as statistically significant. This summer, I have analyzed over 750 photos from Roughtongue Reef taken in 2011. The average number of sponges per photo totaled to 4.16, much lower than the 21.1 figure from the same reef only three years later.

My next steps are to analyze the 625 photos from the Alabama Alps Reef in 2011 and
determine if my results are statistically significant. In addition, I will need to find the images collected between 1997 and 1999 during the Mississippi–Alabama Pinnacle Trend Ecosystem Monitoring program to place these results in context of historical populations of sponges in the area. I have made progress on writing out portions of my thesis itself that I am able to without all of the results; my Introduction and Methods and Materials sections are nearly complete.

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