Friday, February 21, 2014

Emily Hladky's Internship, Spring 2014 - Part 3

In the previous blog I mentioned that I picked benthic foraminifera from cores that were collected in the Gulf of Mexico in order to determine the effects of the Deepwater Horizon oil spill. I wanted to give some general background on foraminifera, what they are, why they are used in science, and so on. Foraminifera are protists that create an external shell or test, often made of calcium carbonate or agglutinated sediment particles. They are very small, about 100 micrometers, but can range in size. There are hundreds of different species that vary in appearance and may only be found in certain environments. Some factors that control the location of specific species include temperature, salinity, wave action, depth, sedimentation rates, turbulence, oxygen concentrations, organic flux, etc. (Gooday, 2003).

Foraminifera play an important role in science, specifically in paleoclimatology and paleoceanography. Foraminifera are used because they are found throughout all oceans, they evolve very quickly, their shells are hard and are therefore preserved in the geologic record, but most importantly, they are very sensitive to changes in the environment and can serve as indicators of the health of a community. The diversity of the community changes with a changing environment, which is what I am currently researching in the Gulf. I have seen changes in species diversity and abundance in the Gulf as a result of the oil spill. As mentioned in the last blog, diversity seems to decrease, and we found the dominant taxa present in all three cores to be Bulimina aculeata and Uvigerina peregrina. Bulimina spp. are often found in environments with low oxygen (Miller and Lohmann, 1982), and Uvigerina spp. are found where there are low oxygen levels and high organic carbon flux (Miller and Lohmann, 1982); pictures of these species can be seen below. I recently began looking at cores collected in February and September of 2011 and will be comparing the foraminiferal assemblages from these cores to the ones already completed to determine how these communities are recovering, if they are recovering at all.

Bulimina aculeate

Uvigerina peregrina
 
References: 
Gooday, A.J., 2003. Benthic Foraminifera (Protista) as Tools in Deep-water Palaeoceanography: Environmental Influences on Faunal Characteristics. Advances in Marine Biology, Academic Press.

Miller, K.G. Lohmann, G.P., 1982. Environmental distribution of Recent benthic foraminifera on the northeast United States continental slope, in: Lohmann, G.P. (Ed.). Geological Society of America Bulletin, pp. 200-206.  

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Emily Hladky - St. Petersburg, FL

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