Abstract:

Seven phytoplankton cultures acclimated at four different high/low salinity and temperature combinations were exposed to three types of exposure solutions: 1) water accommodated fractions (WAFs), 2) chemically enhanced WAFs (CEWAFs), and 3) dispersant only solutions (DOSs) at concentrations of 25% and 50% as well as control solutions. In vivo fluorescence was measured twice weekly for 23 days, as a proxy measurement of chlorophyll concentration. Triplicate samples of WAFs and CEWAFs were analyzed for target hydrocarbons.

Suggested Citation:

Tyre, K., Parsons, M.L., Overton, E.B.. 2020. Phytoplankton responses to crude oil and chemical dispersant exposure in laboratory culture: in vivo fluorescence and hydrocarbon data. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/4NJG5PEH

Publications:

Quigg, A., Parsons, M., Bargu, S., Ozhan, K., Daly, K. L., Chakraborty, S., … Buskey, E. J. (2021). Marine phytoplankton responses to oil and dispersant exposures: Knowledge gained since the Deepwater Horizon oil spill. Marine Pollution Bulletin, 164, 112074. doi:10.1016/j.marpolbul.2021.112074

Purpose:

High phytoplankton productivity is characteristic of many coastal environments and is depended upon to sustain local fisheries. Any environmental disruption could result in a deleterious trophic cascade effect, crippling important fisheries. Oil spills carry the potential to create such a disruption and can be expected to increase in frequency as offshore oil exploration continues to expand worldwide. The aim of this study was to assess the exposure response of common phytoplankton to crude oil and chemical dispersant in a laboratory setting.

Data Parameters and Units:

Worksheet “in vivo fluorescence”: Species: user-defined identifier for the phytoplankton species culture used in the exposure treatment; Day: Number of elapsed days from the start of experiment; Date: Date in vivo fluorescence was measured; Salinity (ppt): Salinity the phytoplankton culture was maintained; Temperature (deg C): Temperature the phytoplankton culture was maintained; Treatment: Type of exposure treatment (CEWAF, CEWAF Control, Culture Control, DOS, DOS Control, Media Control, WAF, WAF Control); Toxicant Concentration (%): Concentration of the exposure solution/control, expressed in percent (0, 25, 50); Replicate: indicator of the replicate (1,2,3); RFU: in vivo fluorescence, expressed in relative fluorescence units. Worksheet “hydrocarbon analysis” Surrogate corrected values for 28 alkane analytes (µg/l) and 43 aromatic analytes (µg/l) for triplicate samples of WAFs and CEWAFs prepared independently in the laboratory.

Methods:

In vivo fluorescence, measured twice weekly via Turner 10-AU fluorometer, was used as a proxy measurement of chlorophyll concentration. To account for fluorescence signal interference from oil components, control solutions containing seawater, chemical dispersant, and crude oil were prepared and measured along with the phytoplankton exposures. The fluorescence signal from the control group was subtracted from the exposure group. Triplicate samples of WAFs and CEWAFs were analyzed for target hydrocarbons. As there are thousands of compounds in crude oil, only the most abundant, most common, and most toxic were targeted for analysis. The samples were liquid-liquid extracted with methylene chloride, and the extracts were analyzed by Gas Chromatography - Mass Spectrometry (GC-MS). Analysis by GC-MS used an Agilent 7890A GC system configured with a 5% diphenyl/95% dimethyl polysiloxane high resolution capillary column (30-meter, 0.25 mm ID, 0.25 micron film) directly interfaced to an Agilent 5975 inert XL MS detector system. The MS was operated in the Selective Ion Monitoring (SIM) mode to maximize the detection of the target constituents unique to crude oil. The concentrations of target PAHs were determined by an internal standard method and response factors calculated from a 5-point calibration curve using commercially available standard containing the normal alkanes from n-C10 through n-C35 and the parent PAH analytes of interest. SPECIES TESTED FP-N2 = Psuedo-nitzschia sp. TSKE3 = Skeletonema sp. TODO0 = Odontella mobiliensis TCHA1 = Chaetoceros sp. LTHA3 = Thalassiosira sp. KFLA1 = Amphidinium sp. BCYA1 = Synechoccales sp. TREATMENTS 15ppt = 15 ppt salinity 34ppt = 34 ppt salinity WAF 25% = Water Accommodated Fraction of crude oil mixed with seawater diluted 1:3 with nutrient enriched seawater WAF 50% = Water Accommodated Fraction of crude oil mixed with seawater diluted 1:1 with nutrient enriched seawater DOS 25% = Dispersant Only Solution comprised of chemical dispersant mixed with seawater diluted 1:3 with nutrient enriched seawater DOS 50% = Dispersant Only Solution comprised of chemical dispersant mixed with seawater diluted 1:3 with nutrient enriched seawater CEWAF 25% = Chemically Enhanced Water Accommodated Fraction of crude oil and chemical dispersant mixed with seawater diluted 1:3 with nutrient enriched seawater CEWAF 50% = Chemically Enhanced Water Accommodated Fraction of crude oil and chemical dispersant mixed with seawater diluted 1:1 with nutrient enriched seawater WAF Control = WAF solution with no live cells added DOS Control = DOS Solution with no live cells added CEWAF Control = CEWAF solution with no live cells added Culture Control = nutrient enriched seawater containing live cells but no crude oil or chemical dispersant Media Control = nutrient enriched seawater containing no live cells, crude oil, or chemical dispersant

Instruments:

Turner 10-AU fluorometer.

Individual Files: