Abstract:

Results from experiments to investigate and quantify defecation rates of crude oil by 3 species of marine planktonic copepods (Temora turbinata, Acartia tonsa, and Parvocalanus crassirostris) and a natural copepod assemblage after exposure to mechanically or chemically dispersed crude oil. Experiments consisted of 24-48 hour laboratory incubations of single species of copepods or natural copepod assemblages exposed to crude oil alone or dispersant-treated crude oil (“experimental treatments”), or in absence of crude oil (“control treatments”). To determine the presence of crude oil in fecal pellets, aliquots of fecal pellets fixed with glutaraldehyde were viewed under an epifluorescence microscope with bright-field and UV illumination. Images of fecal pellets with both bright-field and UV illumination were captured with a digital camera attached to the microscope.

Suggested Citation:

Rodrigo Almeda. 2016. Oil droplet counts and volumes in fecal pellets of planktonic copepods (Temora turbinata, Acartia tonsa, and Parvocalanus crassirostris) exposed to crude oil and dispersant-treated oil emulsions. Distributed by: Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC), Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7028PK1

Publications:

Almeda, R., Connelly, T. L., & Buskey, E. J. (2016). How much crude oil can zooplankton ingest? Estimating the quantity of dispersed crude oil defecated by planktonic copepods. Environmental Pollution, 208, 645–654. doi:10.1016/j.envpol.2015.10.041

Purpose:

To determine defecation rates of dispersed crude oil by adult stages of planktonic copepods, and estimate the quantitative impact of ingestion and defection of dispersed crude oil by copepods to the fate of crude oil after spills.

Data Parameters and Units:

Dataset consists of 3 files and 1 folder (plus subfolders): FILE: data for GRIIDC_crude oil defecation by planktonic copepods.xlsx Tabs in file correspond to tables and figures in Almeda R, Connelly TL, Buskey EJ (2016) How much crude oil can zooplankton ingest? Estimating the quantity of dispersed crude oil defecated by planktonic copepods. Environmental Pollution 208:645-654 Tab Table1: prosome lengths of studied copepods in µm, mortality % of copepods in different treatments, fecal pellets produced per copepod per day, oil content per fecal pellet in ng oil per pellet, crude oil defecation rate in ng oil per copepod per day, crude oil defecation rate in µg oil per µg C copepod Tab Fig.2A: Percent of fecal pellets containing crude oil droplets after exposing copepods Temora turbinata, Acartia tonsa, Parvocalanus crassirostris and natural copepod assemblages (Community) to crude oil (Oil) or dispersant treated oil (Oil+Disp) emulsions Tab Fig.2B: Mean fecal pellet volume (µm3) after exposing copepods Temora turbinata, Acartia tonsa, Parvocalanus crassirostris and natural copepod assemblages (Community) to crude oil (Oil) or dispersant treated oil (Oil+Disp) emulsions Tab Fig.3: Mean and median size/diameter (µm) of crude oil droplets inside the fecal pellets Tab Fig.4: Mean/median number of crude oil droplets per pellet, Mean/median volume (µm3) of oil per fecal pellet Tab Fig.5: Copepod body weights (µg C) and crude oil defecation rates (ng oil per copepod per day) by species and treatment FILE: diameter and volume per oil droplet in fp.csv Diameters and volumes of individual oil droplets in all fecal pellets Column 1: Label -- image name Column 2: Major -- major axis diameter (µm) Column 3: Minor -- minor axis diameter (µm) Column 4: Treatment -- treatment name Column 5: Replicate -- replicate within treatment Column 6: vol.um3 -- calculated volume of oil droplet in µm3 (volume = 4/3*pi*(major axis/2)*(minor axis/2)^2) Column 7: Species -- copepod species FILE: total oil volume and count per fp.csv Total volume of oil and number of droplets in each fecal pellet Column 1: Treatment -- treatment name Column 2: Replicate -- replicate within treatment Column 3: Label -- image name Column 4: vol.um3.fp -- total volume of oil in fecal pellet in µm3 Column 5: Oil.count.fp -- total number of oil droplets in fecal pellet Column 6: Species -- copepod species FOLDER: fecal pellet images Bright-field and UV illumination images of copepod fecal pellets containing oil droplets. Image names correspond to the Label column in the csv data files Contains 4 subfolders (1 subfolder for each species of copepod used in the experiments) -- Temora, Parvocalanus, Acartia, Community Each subfolder contains 4 folders of fecal pellet images (1 folder for each treatment+replicate combination) -- OilA, OilB, OilDispA, OilDispB

Methods:

Light Louisiana sweet crude oil and Corexit 9500A were used for the oil and oil+dispersant treatments respectively. Treatments consisted of control (no oil or dispersant), oil (exposure to 1 uL/L of crude oil), and oil + disp (exposure to 1 uL/L dispersant treated crude oil). Each treatment was run twice (replicates A and B). Species treatments (T. turbinata, P. crassirostris, and A. tonsa) were incubated 48 hrs while the community group was incubated for 24 hrs.

Individual Files: