Sea-ice algae exposed to crude oil. Sea-ice algae

Crude oil spills in the Arctic can be expected to cause lethal impacts to primary producers such as sea-ice algae and phytoplankton that are contacted by high concentrations of oil. Less well constrained are the sublethal impacts of low concentrations of crude oil contamination on these primary producers and how sublethal impacts may be modulated by other variables such as declining snow cover and thinning ice due to climate change. Sea-ice algae are a key component of the base of the Arctic food web, especially in spring before adequate light can stimulate phytoplankton to bloom. We determined the concentration of Alaska North Slope (ANS) crude oil that inhibits growth by 10% (IC10) and 50% (IC50) for sea-ice diatoms isolated from Utqiagvik, Alaska and how these toxicological parameters are impacted by changes in light that occur rapidly over the spring as snow and ice melt. Sea-ice diatom isolate genetic response to crude oil contamination and elevated irradiance was characterized by whole transcriptome sequencing. These gene expression profiles were compared with sea-ice algae communities freshly collected from Utqiagvik ice cores and incubated under the same levels of crude oil contamination in addition to irradiance increases in the lab. The gene expression profiles from cultured isolates and natural sea-ice algal communities will be analyzed to develop biomarkers for rapid quantification of sublethal effects of crude oil contamination on ice algae that can be used to assess the sublethal impacts of a spill and differentiate these from other sources of oxidative stress such as high light.