Abstract:

A mesocosm experiment was carried out using natural seawater from the Gulf of Mexico to look at how phytoplankton community composition changed in response to oil and dispersant exposure. The phytoplankton genera present in each tank was recorded after 72h of exposure using a light microscope.

Suggested Citation:

Laura Bretherton, Manoj Kamalanathan, Jennifer Genzer, Jessica Hillhouse, Antonietta Quigg. 2017. Phytoplankton community response to crude oil and dispersants in four different mesocosm treatments after 72h. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7028PMG

Publications:

Bretherton, L., Kamalanathan, M., Genzer, J., Hillhouse, J., Setta, S., Liang, Y., … Quigg, A. (2019). Response of natural phytoplankton communities exposed to crude oil and chemical dispersants during a mesocosm experiment. Aquatic Toxicology, 206, 43–53. doi:10.1016/j.aquatox.2018.11.004

Purpose:

Phytoplankton community structure can be profoundly altered in response to changes in environmental variables. This data was collected to assess how oil spills and chemical dispersants affect phytoplankton community ecology in the Gulf of Mexico.

Data Parameters and Units:

Treatment (CONTROL; WAF=Water Accommodated Fraction of oil; DCEWAF=Diluted Chemically Enhanced Water Accommodated Fraction of oil; CEWAF=Chemically Enhanced Water Accommodated Fraction of oil); Replicate (A, B, C; represent different replicate tanks); Chaetoceros (phytoplankton genus, 1=present, 0=absent); Coscinodiscus (phytoplankton genus, 1=present, 0=absent); Cylindrotheca (phytoplankton genus, 1=present, 0=absent); Lioloma (phytoplankton genus, 1=present, 0=absent); Navicula (phytoplankton genus, 1=present, 0=absent); Nitzschia (phytoplankton genus, 1=present, 0=absent); Pseudo-nitzschia (phytoplankton genus, 1=present, 0=absent); Skeletonema (phytoplankton genus, 1=present, 0=absent); Stephanopyxis (phytoplankton genus, 1=present, 0=absent); Synedra (phytoplankton genus, 1=present, 0=absent); Thalassionema (phytoplankton genus, 1=present, 0=absent); Thalassiosira (phytoplankton genus, 1=present, 0=absent)

Methods:

Natural seawater was collected from a coastal buoy in the Gulf of Mexico and brought back to Texas A&M University at Galveston for manipulation. Treatments were prepared in specialized glass tanks called WAF makers using the natural seawater. WAF treatments were prepared by adding Macondo crude oil to a target concentration of 1mg L-1, and CEWAF treatments were made with a stock solution containing a 20:1 ratio of oil:Corexit. One third of the CEWAF was then diluted until the crude oil concentration was consistent with the WAF to make the DCEWAF treatments. Control treatments were not exposed to either oil or Corexit. The experiments were then set up in 100L glass tanks staged in a room fitted with fluorescent bulbs. All treatments were grown in triplicate with true biological replication. A 100mL sample was taken from each mesocosm tank after 72h and settled for 24h in an Utermohl chamber fitted with a 100mL cylinder. The plate was then removed to look at the sample under an inverted light microscope. All phytoplankton observed on the plate were identified to genus level using Tomas (1997). Representative photographs were taken using the attached camera and processed using Leica Application Suite (LAS) EZ v1.6.0. To calibrate the measurements recorded by LAS EZ software, a photograph of a micrometer was taken with the microscope’s camera and a known distance of 200µm was measured to determine the number of pixels (px) within that set distance. The resulting ratio (1px = 0.32µm) was used to calibrate measurements taken with the microscope and camera. Photographs can be found in GRIIDC dataset UDI: R4.x263.000:0017.

Instruments:

Utermohl chamber - Combined Plate Chamber, Hydro-Bios, Germany Inverted light microscope - Motic AE31, British Columbia, Canada

Individual Files: