Hormonal and reproductive effects of low levels of petroleum fouling in magellanic penguins (Spheniscus magellanicus)

Petroleum fouling has many deleterious consequences for marine vertebrates, ranging from increased energy expenditure to the death of the organism. We measured circulating levels of reproductive and adrenocortical hormones in Magellanic Penguins (Spheniscus magellanicus) that were partially covered with petroleum following a marine oil spill off the Patagonian coast, and in a non-oiled control group. Levels of luteinizing hormone, androgens and estradiol, but not progesterone, were lower in oiled penguins than non-oiled control birds. Corticosterone was higher in oiled than control females, but did not differ and was basal in males. Few of the pairs with an oiled partner later established nests with eggs. Even low levels of oil fouling in Magellanic Penguins appear sufficient to interfere with reproduction. Oiled penguins that were held captive for washing had elevated levels of corticosterone, and appeared to be stressed both by captivity and by the washing process.