A case study of zooplankton response to oil contamination as a predicted consequence of Pipeline 5 failure in the Straits of Mackinac, Michigan

Abstract

Oil spills are known to harm aquatic environments, and the potential failure of an underwater oil pipeline, Line 5, threatens the Great Lakes. The objective of this study was increased understanding of freshwater oil exposure, looking at (a) zooplankton survivability; (b) zooplankton oil bioaccumulation; and (c) chlorophyll concentrations as phytoplankton health indicators. Two study sites were selected near Line 5 (Douglas Lake-Pellston and Lake HuronCheboygan). Water and organism samples were collected at each site and exposed for 3 days to 0 ppm, 500 ppm, and I 000 ppm of oil (in 3 oxygenated tanks per treatment per site). Zooplankton survival assessment (live counting) was done daily. Biomass filtering was done on the last day to assess zooplankton oil bioaccumulation and chlorophyll concentrations. Results showed significant correlations for zooplankton oil bioaccumulation at both sites, almost significant chlorophyll correlations at Lake Huron, and no significant correlations for zooplankton survivability at either site, perhaps due to sampling errors, insufficient exposure duration, and insufficient natural conditions in the laboratory. Results suggest that a Line 5 oil spill will negatively impact the Great Lakes, likely inhibiting phytoplankton and dependent trophic levels and facilitating oil bioaccumulation up the food chain.