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

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.