Abstract:

In order to understand the role of biodiversity in increasing resiliency to perturbation, a set of experiments were conducted to examine the response of microplankton to the oil perturbation conditions present in 2016 and 2017. Results of various treatments where cells respond to 1 ppm of water-accommodated fraction (WAF) of crude oil, 1 ppm of chemical-enhanced WAF (using industrial dispersant, CEWAF), dispersant only (Disp, using volume of dispersent without crude) and control conditions, are reported here. All experiments received 1 ppm petrocarbon addition except June 2016 (10 ppm with associated WAF, CEWAF, Disp treatments).

Suggested Citation:

Krause, Jeffrey; Thamatrakoln, Kimberlee; Cole, Liesl; Acton, Sydney. 2019. Seasonal effects on microplankton response to oil perturbation on Mississippi-Alabama shelf, Gulf of Mexico from 2016-01-24 to 2017-03-16. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-w8zg-tj49

Purpose:

To examine the resiliency of microplankton standing stock and activity in response to petrocarbon loading in the water.

Data Parameters and Units:

Sampling Site Latitude (N, decimal degrees); Sampling Site Longitude (E, decimal degrees); Experiment (YYYY_Month); Experimental Time point Date (MM/DD/YYYY); Experimental Time point (Hours since start); Treatment (C, WAF, CEWAF, Disp); Replicate (A, B, C, D); Nitrate+Nitrite (micromoles per liter); Nitrite (micromoles per liter); Ammonium (micromoles per liter); Total dissolved nitrogen (micromoles per liter); Dissolved silicic acid (micromoles per liter); Chlorophyll a, greater than five micron size fraction (micrograms per liter); Chlorophyll a, greater than 0.6 micron size fraction (micrograms per liter); Primary productivity, greater than five micron size fraction (micromole carbon per liter per day); Primary productivity, greater than 0.6 micron size fraction (micromole carbon per liter per day); Notes. NO data is denoted as -999.

Methods:

Samples were collected at the listed coordinates and transported to the Dauphin Island Sea Lab. Water was homogenized, split among treatment containers, modified among the petrocarbon treatments, and incubated (1 - 4 days). Nutrient, pigment and activity methods are as in Dzwonkowski et al.,2017 (doi:10.1016/j.csr.2017.05.001). WAF and CEWAF solutions made following Singer et. al.,2000 (doi:10.1016/S0025-326X(00)00045-X) with modifications: 10g of MC252 Crude Oil Surrogate was added to 800 mL of 0.2µm pre-filtered seawater water. CEWAF had 0.6 mL of Slickgone NS dispersant (Dasic International) in addition to the oil (1:20 Slickgone to crude oil). Negative controls of just dispersant consist of 0.6 mL of Slickgone in 800mL of water. Mixtures are shaken for ~48 hrs and irradiated (~1000 uE m-2 s-1) for 12 hours to simulate weathering in surface-ocean conditions. Mixtures were separated and analyzed for total petroleum hydrocarbon content using dichloromethane and analyzed on a Trilogy Fluorometer (Turner Designs, Sunnyvale, CA) using a Crude Oil Module relative to standard curves made with the known mass of MC252 Surrogate.

Provenance and Historical References:

Dzwonkowski, B., Greer, A.T., Briseño-Avena, C., Krause, J.W., Soto, I.M., Hernandez, F.J., Deary, A.L., Wiggert, J.D., Joung, D., Fitzpatrick, P.J. and O’Brien, S.J. (2017). Estuarine influence on biogeochemical properties of the Alabama shelf during the fall season. Continental Shelf Research, 140, 96–109. doi:10.1016/j.csr.2017.05.001 Singer, M. M., Aurand, D., Bragin, G. E., Clark, J. R., Coelho, G. M., Sowby, M. L., & Tjeerdema, R. S. (2000). Standardization of the Preparation and Quantitation of Water-accommodated Fractions of Petroleum for Toxicity Testing. Marine Pollution Bulletin, 40(11), 1007–1016. doi:10.1016/s0025-326x(00)00045-x

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