The spill area hosts 8,332 species, including more than 1,270 fish, 604 polychaetes, 218 birds, 1,456 mollusks, 1,503 crustaceans, 4 sea turtles and 29 marine mammals.[188][189] Between May and June 2010, the spill waters contained 40 times more polycyclic aromatic hydrocarbons (PAHs) than before the spill.[190][191] PAHs are often linked to oil spills and include carcinogens and chemicals that pose various health risks to humans and marine life. The PAHs were most concentrated near the Louisiana Coast, but levels also jumped 2–3 fold in areas off Alabama, Mississippi and Florida.[191] PAHs can harm marine species directly and microbes used to consume the oil can reduce marine oxygen levels.[192] The oil contained approximately 40% methane by weight, compared to about 5% found in typical oil deposits.[193] Methane can potentially suffocate marine life and create "dead zones" where oxygen is depleted.[193]