Abstract:

Data from an experiment assessing the influence of the presence of (and bioturbation by) ghost shrimp on the distribution of oil that was initially present in a subsurface layer of the sediment. Experiments were conducted in laboratory microcosms (cores), comparing the oil distribution in cores with ghost shrimp to that in cores without ghost shrimp.

Suggested Citation:

Klerks, Paul and Louka, Febee. 2017. Microcosm experiment assessing influence of ghost shrimp on distribution of oil. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7N014XF

Publications:

Klerks, P. L., Kascak, A., Cazan, A. M., Franco, M. E., & Louka, F. R. (2020). A Mesocosm Assessment of the Effect of Bioturbation by the Ghost Shrimp ( Lepidophthalmus louisianensis ) on the Fate of Petroleum Hydrocarbons in the Intertidal Zone. Environmental Toxicology and Chemistry, 39(3), 637–647. doi:10.1002/etc.4652

Purpose:

To assess whether the presence of a bioturbator (in this case the ghost shrimp Lepidophalmus louisianensis) affects the distribution of oil that had previously penetrated the sediment (i.e. buried oil).

Data Parameters and Units:

Sheet with experimental details: microcosm identification, oil treatment, animal treatment, ghost shrimp survival, depth in cm of shrimp (relative to feldspar marker in microcosm upon dismantling), maximum depth of burrow in cm, note on shrimp burrowing. Sheet with PAH data: microcosm ID, sediment layer sampled, sample ID, oil treatment, animal treatment (ghost shrimp present/absent), concentrations for each individual PAH (in µg/kg dry sediment) and total PAH concentration (sum of the individual PAH concentrations, in µg/kg). Only a subset of the microcosms (E1, E2, F1, F2) were analyzed for PAHs during the grant period.

Methods:

The experiment was conducted in 24 microcosms, consisting of PVC cores (50 cm length; 10.16 cm diameter) filled with 30 cm of sieved natural sediment (from Bay St. Louis) and about 5 cm of overlying water (at about 15 ppt salinity). Some cores (8) received no oil, while the other 16 cores had a layer of oil mixed with feldspar (as a visual tracer for the oil layer) at 1/3rd of the depth. The control cores and half of the oil-containing cores received a single ghost shrimp (from Bay St. Louis), while the other cores did not. The cores were dismantled after 7 days. Shrimp survival and their position in the cores was recorded. Three 4-cm layers of each core were taken for PAH analysis: (1) 2-6 cm above the oil/feldspar layer, (2) from 2 cm above the oil/feldspar layer to 2 cm below the feldspar layer, and (3) from 2 cm below the feldspar layer to 6 cm below the feldspar layer. The collected sediment samples were transferred to the lab in a cooler, and frozen upon arrival. All samples were then freeze-dried using an SP Scientific freeze dryer (Sentry 2.0). Dry samples were homogenized using mortar and pestle, and 20 g of sediment was placed in Teflon microwave tubes with 25 mL of DCM. One Touch Technology MARS microwave extraction was performed using the US EPA 3546 method. The DCM containing the extracted PAHs was then filtered by gravity filtration and the remaining sediment was then washed several times with DCM, the DCM was filtered again, and combined in order to recover all the extracted PAHs. The DCM was evaporated using a rotary evaporator. The remaining residue was then dissolved in hexane. The round-bottom flask was rinsed with hexane several times in order to maximize recovery of PAHs in the sample. All the hexane rinses were combined and concentrated in a vial to a volume of 1.00 mL by purging nitrogen gas into the vial. An aliquot of each extracted sample was injected immediately into the GC-FID or was frozen for analysis on the following day. The injections were done using the following conditions: The injector and detector temperatures were set at 250 and 300 deg C, respectively; helium was used as the carrier gas; samples were injected in the splitless mode; the oven temperature was programmed from a 60 deg C initial temperature to increase to 300 deg C at a rate of 5 deg C /min, was then decreased to 290 deg C, and was maintained at this temperature for 25 minutes.

Instruments:

Instrumentation information is provided in the methods section.

Error Analysis:

The Gas Chromatography instrument was calibrated prior to every use. Calibration curve was obtained using Restek PAH standard with exact concentrations. An internal standard was added to all samples prior to analyses. Replicates of samples in presence and in absence of bioturbators were performed for accuracy, as were analyses of samples from mesocosms to which no oil had been added.

Individual Files: