Researchers looking at sediment, seawater, biota, and seafood found toxic compounds in high concentrations that they said was due to the added oil and dispersants.[161] Although Gulf fisheries recovered in 2011,[162] a 2014 study of the effects of the oil spill on bluefin tuna by researchers at Stanford University and the National Oceanic and Atmospheric Administration, published in the journal Science, found that toxins released by the oil spill sent fish into cardiac arrest. The study found that even very low concentrations of crude oil can slow the pace of fish heartbeats.