Abstract:

Water samples were fixed with formalin (2% v/v final concentration), stained with DAPI (45μM final concentration), and visualized on a Zeiss Axio Imager 2 microscope. Bars represent 20μm. The DAPI-stained cells appear blue while oil(as WAF or water accomodated fraction)/Corexit appears orange.

Suggested Citation:

Doyle, Shawn; Sylvan, Jason. 2016. False-colored photographs of micro-scale microbial aggregates collected from four different mesocosm treatments after 48 hours. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7FF3QCP

Publications:

Quigg, A., Passow, U., Chin, W.-C., Xu, C., Doyle, S., Bretherton, L., … Santschi, P. H. (2016). The role of microbial exopolymers in determining the fate of oil and chemical dispersants in the ocean. Limnology and Oceanography Letters. doi:10.1002/lol2.10030

Purpose:

To search for the presence of and examine the structure of microbe-oil aggregates in four different costal water mesocosm treatments.

Data Parameters and Units:

T4-CTRL-A-Aggregate3 represents control mesocosm treatment of seawater + natural particles. T4-WAF-A-Aggregate1 represents WAF mesocosm treatment of seawater + natural particles + WAF (water accommodated fraction of oil). T4-CEWAF-A-Aggregate3 represents CWAF mesocosm treatment of seawater + natural particles + WAF with Corexit. T4-DCEWAF-A-Aggregate2 represents a 10-fold diluted equivalent of CWAF mesocosm treatment of seawater + natural particles + WAF with Corexit. Mesocosm methods – COASTal water with coastal microbial concentrate, COAST. Twelve 100L mesocosm tanks were filled with Gulf of Mexico seawater collected 5 miles off shore from Galveston (TX) that had been pre-treated with a charcoal filter to remove large particles and debris. Plankton (> 63 um) were collected using a net and transferred into polycarbonate bottles. This concentrated plankton mass was introduced to the tanks (2 L to each final volume 83 L) immediately prior to starting the experiments. Four treatments were prepared in triplicate. Control tanks were filled with seawater and plankton mixture. Water accommodated fraction (WAF) of oil was prepared by mixing 25 mL (5 ml ~ every 30 min for 2.5 hrs) of Macondo surrogate oil into 130 L of seawater then mixing for 12 to 24 hrs. (Knap et al. 1986; Knap et al. 2016 in preparation). The WAF was then introduced into the WAF mesocosm tanks and filled to 87 L and mixed. From these WAF tanks 6 L was removed for other experiments and analyses (2L for roller tables, 2 L dark/light, 4 L hydrocarbon analyses). In order to make chemically enhanced water accommodated fraction (CEWAF), Corexit was mixed with oil in a ratio of 1:20 and 25 mL of this mixture (5 ml every 30 min for 2.5 hrs) of surrogate oil plus Corexit was added to 130 L of seawater which was mixed for 8 to 24 hrs prior to being loaded into the mesocosm tanks. The CEWAF was then introduced into the CEWAF mesocosm tanks and filled to 96 L and mixed. From these CEWAF tanks 15 L was removed for other experiments and analyses (9 L for the DCEWAF mesocosms, 2L for roller tables, 2 L dark/light, 4 L hydrocarbon analyses). Diluted CEWAF (DCEWAF) was prepared by mixing 9 L of CEWAF with 78 L of the original seawater for a total volume of 87 L. From these DCEWAF tanks 6 L was removed for other experiments and analyses (2L for roller tables, 2 L dark/light, 4 L hydrocarbon analyses). The estimated oil equivalents (EOE) were determined using Macondo surrogate oil as the calibration standard (Wade et al. 2011) for the fluorescence analyses (Horiba Scientific Aqualog Fluorometer). The EOE mean concentration of the three mesocosms for the control, WAF, DCEWAF and CEWAF at the start of the experiments were 0 mg/L, 0.26 mg/L, 2.74 mg/L and 41.5 mg/L, respectively. The EOE mean concentration of the three mesocosms for the in the control, WAF, DCEWAF and CEWAF after 72 hours were 0 mg/L , 0.06 mg/L, 1.03. and 17.3 mg/L, respectively.

Methods:

Water samples were fixed with formalin (2% v/v final concentration), stained with DAPI (45μM final concentration), and visualized on a Zeiss Axio Imager 2 microscope.

Instruments:

Zeiss Axio Imager 2 microscope

Error Analysis:

NA

Provenance and Historical References:

Knap, A. H., T. D. Sleeter, R. E. Dodge, S. C. Wyers, H. R. Frith, and S. R. Smith. 1983. The effects of oil spills and dispersants use on corals: A review and multidisciplinary experimental approach. Oil and Petrochemical Pollution 1: 157–169. Wade, T.L., Sweet S.T., Sericano, J.L., N.L. Guinasso Jr., Diercks, A.-R., Highsmith, R.C., Asper, V.L., Joung, D., Shiller, A.M., Lohrenz, S.E. and Joye, S.B. 2011, Analyses of Water Samples from the Deepwater Horizon Oil Spill: Documentation of the Sub-Surface Plume. in Monitoring and Modeling the Deepwater Horizon Oil Spill: A Record-Breaking Enterprise, Geophysical Monograph Series, vol. 195, edited by Y. Liu et al., pp. 77–82, AGU, Washington, D. C., doi:10.1029/2011GM001103

Individual Files: