Abstract:

A mesocosm scale experiment was conducted to monitor the temporal changes in microbial hydrocarbon oxidation rates in response to the presence of oil and chemically dispersed oil. Water samples were incubated with 14C labeled hexadecane and naphthalene and the amount of liberated 14C labeled carbon dioxide was measured as a proxy for hydrocarbon oxidation.

Suggested Citation:

Achberger, Amanda, Shawn Doyle, and Jason Sylvan. 2021. Mesocosm: Rates of 14C hydrocarbon oxidation by microbial communities, MICROX, microbial oxidation and degradation of oil and oxidation rate measurements. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-h5zn-gb14

Purpose:

Monitor the temporal changes in microbial hydrocarbon oxidation rates in response to the presence of oil and chemically dispersed oil.

Data Parameters and Units:

The headers are Treatment (Control/WAF/DCEWAF), Substrate (Napthalene/ Hexadecane), Timepoint, Total oxidation per hour (%), Filter+Water oxidation per hour (%), and Filter oxidation per hour (%).

Methods:

The water accommodated fraction (WAF) of oil was prepared by mixing 25 mL (5 ml ~ 5 min over 25 min) of Macondo surrogate oil into six baffled recirculating tanks (Wade et al., 2017) containing ~130 L of seawater were mixed vigorously for 4 hours to create a “high energy” WAF (Knap et al. 1983). The WAF was then introduced into the WAF mesocosm tanks, filled to 104L, and mixed. From these tanks, 3.5 L WAF was removed for hydrocarbon analyses. Corexit was mixed with oil in a ratio of 1:20 to make diluted chemically enhanced water accommodated fraction (DCEWAF). Then 25 mL of this mixture (5 ml every 5 min for 25 min) of surrogate oil plus Corexit was added to a baffled recirculating tank containing ~130 L of seawater which was not vigorously mixed for 4 hours prior to being loaded into the mesocosm tanks. From these CEWAF tanks 5L was removed for other analyses (3.5 L hydrocarbon analyses). Diluted CEWAF (DCEWAF) was prepared by mixing 10.4 L of CEWAF with 93.6 L of the original seawater for a total volume of 104 L. This concentrated plankton mass was introduced to each of the tanks (1.5 L to each tank which contained 104L of treated seawater, total volume of seawater 105.5L per tank) immediately prior to starting the experiments. Banks of lights were placed behind each of the glass mesocosm tanks and a 12:12 light/dark cycle employed.

Provenance and Historical References:

Knap, Anthony H., Thomas D. Sleeter, Richard Eugene Dodge, Sheila C. Wyers, Harold R. Frith, and Struan Robertson Smith. 1983. The effects of oil spills and dispersants use on corals: A review and multidisciplinary experimental approach. Oil and Petrochemical Pollution 1(3):157–169. DOI 10.1016/S0143-7127(83)90134-5 Wade, Terry L., Maya E. Morales-McDevitt, Gopal Bera, Dawai Shi, Stephen T. Sweet, Binbin Wang, Gerado Gold-Bouchot, Antonietta Quigg and Anthony H. Knap. 2017. A method for the production of large volumes of WAF and CEWAF for dosing mesocosms to understand marine oil snow formation. Heliyon 3(10):e00419 DOI: 10.1016/j.heliyon.2017.e00419

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